Alert Diver 2021 Special Edition (DAN World Edition)

2021 SPECIAL EDITION

THE MAGAZINE OF DIVERS ALERT NETWORK

THE ESSENTIAL DIVE SAFETY COLLECTION DAN MEMBERSHIP | DIVE MEDICINE | DIVER SAFETY | DAN RESEARCH

2021 SPECIAL EDITION

THE MAGAZINE OF DIVERS ALERT NETWORK

2021 SPECIAL EDITION

VISION

Publisher Communications Director Managing Editor Editor

Director of Manufacturing and Design Art Director Graphic Artist; Website Editor

Striving to make every dive accident- and injury-free. DAN‘s vision is to be the most recognized and trusted organization worldwide in the fields of diver safety and emergency services, health, research and education by its members, instructors, supporters and the recreational diving community at large.

Stephen Frink Brian Harper Diana Robinson Josh Benjamin Barry Rouxel-Berg Kenny Boyer Diana Robinson

DAN Executive Team William M. Ziefle, President and CEO

Panchabi Vaithiyanathan, COO and CIO

Petar Denoble, Vice President, Research

Simon Morgan, Vice President, IT

Board of Directors Bill Anlyan

Craig Cook

Michael Gernhardt

Michael Lang

Wayne Massey

Joe Poe

Harry Rodgers

Doug Stracener

Kathy Weydig

FOR SUBSCRIPTION OR MEMBERSHIP ASSISTANCE, PLEASE CALL +1-800-446-2671, OR EMAIL member@dan.org

FOR ADVERTISING SALES, PLEASE CONTACT:

Stephen Frink, National Sales Director, sf@stephenfrink.com, +1-305-451-3737 Diana Robinson, Ad Services Manager, drobinson@dan.org, +1-919-684-2948 Volume 37, No. 4

Alert Diver (ISSN 1084-2985) is published quarterly (four times yearly)

by DAN, Inc., 6 West Colony Place, Durham, NC 27705 USA. Alert Diver is a DAN membership benefit; memberships begin at $35 per year. Periodicals rates are paid in Durham, N.C., and other mailing offices.

POSTMASTER: Send address changes to Alert Diver, Address Change, 6 West Colony Place, Durham, NC 27705 USA. CANADA POST Publication Mail Product (Canadian Distribution) Sales Agreement No. 40030231 2|

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Inquiries or letters may be edited for clarity and length. All letters will be considered for publication.

Letters may be sent to letters@dan. org or Editor, Alert Diver, 6 West Colony Place, Durham, NC 27705 USA. Text, illustrations or photographs in Alert Diver may not be reproduced or reprinted without the expressed consent of DAN Inc., and its authors, artists and photographers.

Alert Diver is printed in the USA.

Alert Diver magazine’s printer is FSC® certified, utilizing wellmanaged forestry and wastemanagement practices while using soy-based inks.

DAN is a NC nonprofit corporation.

The DAN Foundation is a 501(c)(3) tax-exempt nonprofit corporation.

ID#56-1696689

MISSION DAN helps divers in need of medical emergency assistance and promotes dive safety through research, education, products and services.

Divers Alert Network® (DAN®), a nonprofit organization, exists to provide expert medical information for the benefit of the diving public.

DAN’s historical and primary function is to provide timely information and assistance for underwater diving injuries, to work to prevent injuries and to promote dive safety.

Second, DAN promotes and supports underwater dive research and education, particularly as it relates to the improvement of dive safety, medical treatment and first aid.

Third, DAN strives to provide the most accurate, up-to-date and unbiased information on issues of common concern to the diving public, primarily — but not exclusively — for dive safety.

ALERT DIVER’S PHILOSOPHY Alert Diver® is a forum for ideas and information relative to dive safety, education and practice. Any material relating to dive safety or dive medicine is considered for publication. Ideas, comments and support are encouraged and appreciated.

The views expressed by contributors are not necessarily those advocated by Divers Alert Network. DAN is a neutral public service organization that attempts to interact with all diving-related organizations or persons with equal deference.

Alert Diver is published for the use of the diving public, and it is not a medical journal.

The use and dosage of any medication by a diver should be under the supervision of his or her physician.

DAN does not sell, lease or trade its mailing lists. The appearance of an advertisement in Alert Diver does not imply endorsement

by DAN of any product or service shown.

Individuals who reply to advertisements in Alert Diver understand that they are volunteering their information to the advertisers and are, therefore, subject to that company‘s mailing policies.

DIVERS CHOOSE DAN There are so many reasons divers choose DAN. + Over 40 years managing diving emergencies worldwide

+ Dive accident insurance plans designed for divers

+ Dedicated medical information line and emergency hotline

+ Safety consultations for dive operators to help reduce risk

+ Wide range of online health and safety resources

+ First aid training for divers and professionals

Latin America: WORLD.DAN.org Asia-Pacific: DANAP.org

C O N T E N T S 2021 SPECIAL EDITION

ON THE COVER: A queen angelfish feeds on a bit of encrusting sponge on the wreck of the City of Washington off Key Largo’s Elbow Reef. Stephen Frink captured this image with a Canon EOS 5D Mark IV camera in a Seacam housing with a Canon 8-15mm fisheye zoom lens at 15mm, Seacam Seaflash 160 strobes and settings of 1/30 sec, f/13 and ISO 320.

THIS PAGE: Barbara Doernbach navigates the narrow chasm leading to Mirror Pond at Leru Cut in the Solomon Islands. Stephen Frink captured the scene using available light, a Canon EOS 5D Mark III camera in a Seacam housing with a Canon 8-15mm fisheye zoom lens at 15mm and settings of f/5.6, 1/80 second and ISO 320.

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6 Perspectives

9 10 16 18 22 26 28 32

MEDICAL SERVICES Stacking the Deck: Applying Lessons Learned to Dive Safety Basics Lionfish Stings Back to Basics: Understanding Decompression Illness Women’s Health and Diving Marine Envenomations: Jellyfish and Hydroid Stings Children and Diving: What Are the Real Concerns?

Uncertainty After Diving: Case Reports and Recommendations

35 36 39 40 42 44 46 50 54 56

MEMBERSHIP AND INSURANCE A Culture of Dive Safety Pneumonia in Germany More Than Just Bubbles: Are We Too Concerned About DCS? Timeline of an Emergency Call Touch and Go in Tonga Professional Liability: Not Just for Pros Divers Losing Access to Emergency Care DCS in Cozumel Reduce Your Liability Risk

57 58 60 62 64 66 68 70 74 76 78 80

SAFETY SERVICES Survive Your Dive: A U.S. Coast Guard Perspective Choosing Safety Preventing Breathing-Gas Contamination Invisible Crystals Experience and Risk You’ll Be OK Freediving Safety What Drowning Really Looks Like Dive Boat Fire Safety The Social Psychology of Safe Diving When Things Go Wrong: Emergency Action Plans

81 82 87 90 92 96 98

RESEARCH Matters of the Heart: Aging, Wellness and Fitness to Dive Delay to Recompression Timing Exercise and Diving PFO and Decompression Illness in Recreational Divers Checklists: Keys to Safer Diving?

Immersion Pulmonary Edema

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PERSPECTIVES

FROM THE ARCHIVES B Y

B I LL

Z I E F LE

IN 1982 DAN STAFF NOTED a growing demand among divers for information about dive medicine. To meet that demand and to enhance communication between DAN and its members, the organization published the first issue of Alert Diver the following year. The magazine, which at the time could more accurately be described as a newsletter, was a benefit of membership and a means to educate divers, dive professionals and even medical professionals about dive medicine.

The first issue included the following statement: “Alert Diver is a forum for ideas and information relative to diving safety, education and practice. It acts as a liaison between DAN’s diving medicine specialists, their health care colleagues, and the diving community at large. Any material that relates to diving safety or diving medicine is considered for publication.”

From that first eight-page, text-only issue, Alert Diver grew over the years to cover not only dive safety and medicine, but also dive research, industry news, incident reports, letters from DAN members, and more. In 2009 DAN expanded the magazine’s purview to feature dive destinations, marine life, underwater photography and other topics of general interest to divers. A renewed emphasis on world-class underwater images was intended to enhance the magazine’s appeal to divers. We knew DAN members were interested in diving, and by sharing stories and images by the world’s most experienced and eloquent dive journalists we believed we could reach even more people with important dive safety messages. After all, a spoonful of sugar helps the medicine go down.

This 2021 Special Edition is a collection of the most relevant and informative dive-safetyrelated articles that DAN has published since the 2009 redesign. We hope you enjoy this curated selection from the Alert Diver archives, and we hope you use the information in these articles to dive safely for years to come.

MEDICAL SERVICES DAN was founded in 1980 as a hotline for injured divers to get access to the medical care they needed. Today DAN Medical Services operates not only the DAN Emergency Hotline, but also the DAN Medical Information Line, specializing in helping divers in emergencies as well as 6 |

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answering questions about fitness to dive. In fielding these calls, DAN medics garner enormous expertise in managing dive emergencies and in-depth knowledge about the implications of diving with various medical conditions.

DAN Medical Services is an invaluable resource for injured divers as well as for divers, dive professionals and medical professionals seeking to prevent dive injuries.

The Medical Services section in this issue of Alert Diver highlights articles that can help guide divers’ responses to the onset of symptoms after diving. It also covers important considerations for responding to hazardous marine life injuries, minimizing your risk of a dive accident and preparing yourself and those you dive with for safe and successful dives.

Services’ work takes place behind the scenes. Throughout the world’s most popular diving destinations are hundreds of chamber facilities that are willing to treat divers but need support. Through DAN’s Recompression Chamber Assistance Program (RCAP), DAN provides chamber assessments, financial aid and consultations thus ensuring DAN members — and all divers — have access to the emergency medical services they need. DAN has also developed the industry’s most relevant and effective tool for helping dive professionals and businesses reduce incidents: the DAN Hazard Identification and Risk Assessment (HIRA) program. Since its creation in 2008, this program has fostered the development of safer diving communities and continues to promote safe operations worldwide.

MEMBERSHIP AND INSURANCE As a membership organization, DAN understands that one of the many appealing aspects of diving is the community of like-minded people with whom we dive.

Divers are united by a love of being underwater, exploring the natural world and sharing adventures. It is DAN’s goal that all divers stay safe during their underwater excursions.

That’s why DAN has published numerous articles promoting a culture of dive safety and encouraging our members to look out for themselves and other divers.

The articles in this issue’s Membership and Insurance section cover the ways that DAN empowers divers and dive professionals to advocate for themselves and each other and ways DAN membership and insurance programs are essential aspects of DAN’s mission to keep divers safe.

RESEARCH For decades DAN Research has conducted studies on safety and medical topics of practical interest to divers.

Some of the department’s most well-known studies are on flying after diving, the effects of aging on diver health, the significance of patent foramen ovale to divers, diabetes and diving, and the causes of decompression illness.

Historically, DAN Research has conducted studies on the water as well as in chambers, and today there are opportunities for divers to take part. In addition to publishing studies in scientific journals and publishing the DAN Annual Diving Report each year, DAN Research hosts workshops and conferences involving industry experts who come together to share knowledge and establish guidelines. DAN also supports the future of dive medical research through the DAN Internship Program.

The final section of this issue features important lessons learned through dive medical research as well as expert opinions from some of the world’s most respected dive scientists. Topics include aging and diving, cardiovascular health and fitness, decompression sickness risk and more.

SAFETY SERVICES The third section of this issue highlights the work of DAN Safety Services, which focuses on preventing incidents by offering first aid training, providing the dive industry with first aid and safety equipment, and helping divers and dive operators mitigate risks. With articles about emergency planning, social pressure and preventing “We knew DAN members were gas contamination, this section interested in diving, and by sharing is all about identifying potential stories and images by the world’s hazards and taking the right steps to manage them. most experienced and eloquent While the dive community is dive journalists we believed we largely familiar with DAN’s first could reach even more people with aid courses and emergency oxygen units, much of DAN Safety important dive safety messages.”

THANK YOU At DAN, everything we do is possible because of you, our members. Thank you for your support. If there are any dive safety topics you would like to see us cover in a future issue of Alert Diver, please don’t hesitate to contact us at Letters@DAN.org. AD DAN.ORG

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MEDICAL SERVICES 10 Stacking the Deck 16 Lionfish Stings 18 Back to Basics: Understanding DCI 22 Women’s Health and Diving 26 Marine Envenomations 28 Children and Diving 32 Uncertainity After Diving

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STACKING THE DECK

A P P LY I N G L E S S O N S L E A R N E D T O D I V E S A F E T Y B A S I C S B Y

N I C H O LA S

B I R D ,

M. D . ,

MM M

THERE IS A CERTAIN WANDERLUST among divers. Like the seafaring explorers of old, many in the diving community travel farther, dive deeper and consistently search the horizon and plumb the depths for new adventure. As a group, we are continually seeking ways to safely spend more time in the water. Since diving became a recognized endeavor for the general public, training organizations have worked diligently to provide techniques and procedures that facilitate safety and enjoyment.

Divers Alert Network® (DAN®) was founded 30 years ago with dive safety as its core mission.

Over time, DAN’s reach has expanded to include research, training and a robust medical call center for divers. DAN’s services include medical referrals, consultation, evacuation assistance and repatriation. Over the course of our history, we have learned many lessons about dive safety and accident prevention.

These lessons are based on our collective experience and are the synthesis of years of accident management. With time, we have noted recurring issues associated with poor outcomes, many of which were avoidable. The majority of accidents that could have been avoided are the result of multiple factors that come together in a domino effect. Our goal is to support safe practices; and the more you build safety into your travel plans and diving activities, the happier memories you will have of successful trips and the more trouble you will avoid. Let’s take a look at some dive safety basics that, while important every time you dive, are especially important when you’re away from home.

TAKE CARE OF YOURSELF

A critical aspect of dive safety is personal readiness. In this context, readiness encompasses health, physical conditioning, proper skills and equipment preparation. The primary goal here is to ensure that your skills, equipment and health status are commensurate with the type of diving you plan to do and the environmental conditions you expect. Ideally, you should be fit enough to perform comfortably in the anticipated conditions, and your fitness level should provide you with a reserve in case of an emergency. Fatigue and exhaustion may lead to poor decision making and are common triggers of dive accidents. Optimal preparation for diving should include strength and cardiovascular training at least three times a week throughout the year and finswimming training before the dive season.

Health problems may cause accidents directly or indirectly by compromising physical fitness.

DAN fields thousands of informational calls and emails every year and has an extensive referral network of dive-medicine trained physicians to help you. If you have concerns, or if your health status has changed since you last had a dive physical, please call +1–919–684–2948 or contact us via DAN.org/Ask-a-Medic for a referral.

An easy way to decrease the risk of accidents is by keeping your gear in working order. Regulators and buoyancy compensators must be serviced annually. For those diving with rebreathers and other technical equipment, consult your manufacturer’s “These lessons are based on recommendations and have the gear evaluated regularly by a professional, especially our collective experience and in the event of any malfunction. For those diving in cold water, ensure your drysuits are the synthesis of years of are functioning correctly — that seals are intact and valves have been regularly maintained and work perfectly. accident management.”

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STEPHEN FRINK

Nitrox is often used to extend dive times but can alternatively be used to reduce DCS risk if dive times are kept within the no-decompression limits of air dives to the same depth.

Opposite: A thorough buddy check before every dive reduces the risk of forgetting important equipment and serves as a reminder to adjust gear for comfort and security.

When planning a trip, consider how your skills, experience and fitness match up to environmental conditions and requirements of the dive destination.

Reassess your risks before each dive, taking into consideration the actual conditions. Rough water, poor visibility, currents and unfamiliar surroundings can present significant challenges to divers. When combined with gear troubles and poor physical fitness, these factors really set up divers for failure, which in the diving environment may be fatal.

When at a dive site for the first time, seek the assistance of local professionals in assessing dive conditions and risks.

In addition, dive professionals may help you assess your own abilities and limitations and provide the training necessary to ensure your skills match the environment.

SAFER DIVING PRACTICES

Once at the dive site, what can you do to enhance your safety, reduce your risk of decompression sickness (DCS) and further stack the deck in your favor? While the overall risk of DCS is very low, it still occurs and is worth 12 |

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avoiding. Some simple steps you can employ on your next trip may make a difference.

For divers, DCS results from the formation of nitrogen (or other inert gas) bubbles within tissues and blood vessels secondary to a reduction in ambient pressure. Gas dissolved into liquid (bodily tissues and blood) at depth may come out of solution and form bubbles either during or after ascent. Bubbles can cause tissue inflammation and compromise blood flow. The amount of dissolved nitrogen is proportional to the depth and duration of a dive, so decreasing these will reduce the risk of DCS. Longer surface intervals, slow ascents and prolonging the time spent at shallow depths will promote off-gassing — the safe elimination of accumulated inert gas.

Enriched air nitrox (EAN) has less nitrogen than air, so its use by divers results in less nitrogen absorption than similar profiles on air. It should be noted, however, that the safety margin enjoyed with nitrox is achieved only by diving air tables or equivalent computer settings. When divers set their computers for nitrox with the intention of extending bottom time, this safety margin is lost. The use of nitrox comes with unique safety concerns such as oxygen toxicity and requires proper training.

An additional factor that may impact the incidence of DCS is poor hydration. Hydration has gained attention

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CARLOS VILLOCH/IMAGEQUESTMARINE.COM

for its potential role in reducing DCS risk and for its adjunctive use in medical management (use of IV fluids along with oxygen or hyperbaric oxygen therapy). While hydration alone does not make up for or counteract provocative dive profiles, suboptimal hydration status — often associated with alcohol intake and hot climates — may be associated with increased DCS risk.

to DCS throughout our lifetimes and from one dive to the next, none of which is accounted for by standard tables or computers. Therefore, the no-decompression limits (and decompression instructions in technical-diving computers) should be viewed as guidelines and not representative of absolute or established boundaries that are “safe” so long as they aren’t violated.

MENTAL PREPARATION

HAVE A BACKUP PLAN

Mental preparation is critical for safe diving. Fear, apprehension, fatigue and severe anxiety can compromise decision-making abilities. If you aren’t feeling up to diving or if the conditions or goal of the dive frighten you, don’t go.

You’ve modified your dive practices and added layers of safety, but you want additional preparation and security because you know things can still go wrong.

In addition to personal health, the prepared diver should consider the financial impact of emergent care and evacuation. Dive accident insurance provides financial DIVE PLANNING safety and helps with the high cost of evacuation, With the widespread use of dive computers, dive transportation and medical care. As with any insurance, planning has largely become a lost art. While these incredible know what your policy covers before you leave. Don’t rely little machines do a lot to keep us informed underwater, it on folklore, your dive shop or is important to remember that your instructor. Read the policy, the limits they impose are based and understand the true nature on mathematical algorithms “When planning a trip, consider how that have not been validated your skills, experience and fitness match of your coverage and what exclusions exist. Before buying by experimental research. In up to environmental conditions and dive accident or trip insurance, addition, each of us will have a consider where you will be varying degree of susceptibility requirements of the dive destination.”

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EMERGENCY ACTION PLAN

You’ve completed your pretrip planning and will make adjustments to your dive practices; now what?

Traveling to remote destinations can be wonderful, but remember that if it took a plane, a train, a boat and a donkey to get you there, help will likely require the same route to reach you. This is a sobering reality for those visiting exotic destinations, but it bears consideration.

As a rule of thumb, the further you travel from home or medical services, the more precautions you should employ to stack the deck in your favor. This is why having redundant medical supplies, reliable communication equipment, multiple contact options and medical training is so important. Knowing that the best scenario might be a one- to two-day wait before you can be evacuated encourages good preparation. If you’re traveling with a company, consider asking focused questions to determine how prepared they are for such contingencies and what plans they have in place for evacuation.

This boils down to having an emergency action plan — a guide for what to do when bad things happen. A 14 |

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PHOTOS BY STEPHEN FRINK

traveling and what a worst-case scenario might look like.

These policies are relatively inexpensive when compared to the trip’s cost and the cost of evacuation and medical treatment. If you have questions about what your dive accident or trip insurance policy covers, call and ask.

Another area of pretrip preparation that warrants attention is your medical needs. Be sure to bring enough medication with you when you travel to last the entire trip plus a few days after you return home. If the list of medications you take is long or complex, consider carrying a written list in the event of unexpected need. If you have a complicated health history, discuss your trip with your doctor, and take a detailed health history with you in case emergent medical intervention is required. Travel health risks vary from region to region; up-to-date information may be obtained from the Centers for Disease Control and Prevention’s website (CDC.gov).

Health status requirements can vary greatly among different resorts, charter operators and dive shops. We recommend calling well ahead of time to see what they require, whether they have forms you can fill out and what sort of documentation they will use to ensure you meet their standards for medical fitness to dive. By addressing these issues early and proactively, you will encounter fewer roadblocks and unexpected restrictions.

An aspect of emergency preparedness often forgotten is filing a trip plan with family or friends. Trip plans should include contact numbers, medical history, medication lists, allergies and flight plans. Such information can prove vital in the event of poor international telephone connections or spotty satellite phone coverage.

Clockwise from top: Regular exercise is important for staying in diving shape. • Talk to your doctor about any medications you take before you use them while diving. • Dive computers are invaluable but do not replace the need to “plan your dive and dive your plan.” • Good hydration is important for general health and may be associated with a reduced risk of DCS. • Predive briefings ensure divers are on the same page with regard to depths, turnaround times and hand signals to be used.

substantial part of many people’s plans is to call DAN. This is an important step, but it’s only one part. DAN is here 24/7/365 to field calls, provide medical information, facilitate referrals and coordinate evacuations, but we can’t provide care over the phone or on the boat, island or lake. This is where your contingency planning and medical training (or that of your dive/travel operation) comes into play.

An integral part of a good trip is a safe return with wonderful memories. The more personal responsibility you take for your own safety and well-being, the more likely it is that you will enjoy trouble-free adventures. If trouble does occur, adequate preparation, planning and a thoughtful approach will boost your confidence and minimize the extent of complications and injuries. AD

MEDICAL SERVICES Lionfish are fascinating and beautiful creatures, but they can cause serious injuries as well as environmental problems outside their normal range. Population control projects are one way to manage the spread of lionfish.

STEPHEN FRINK

LIONFISH STINGS B Y

J O R G E

D A R I O

GO M E Z

C AS T IL L O ,

M . D .

INDO-PACIFIC LIONFISH (Pterois volitans) have invaded many popular scuba diving locations in the Atlantic and Caribbean. Aside from causing possible harm to swimmers and divers, this voracious predator can dramatically affect populations of native marine animals in the ecosystems to which they have been introduced.

Lionfish are venomous and belong to the Scorpaenidae family. These fish and those of the Synanceiidae family (such as Synanceia, or stonefish) comprise most of the existing venomous fish. Without putting life at risk, envenomations caused by scorpionfish and lionfish can cause significant symptoms due to the systemic action of their venoms.

Lionfish have spines that are covered by an epithelial sheath containing venom-producing glands in the grooves of the upper two-thirds of the long and slender spines. The dorsal fin has 12-13 rays or spines, the pelvic fin has two, and the anal fin has three. When the ray of the fin penetrates the 16 |

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RESPONDING TO A LIONFISH STING • Clean the wound by thoroughly washing the area with soap and fresh STEPHEN FRINK

water. Remove any foreign material, and control bleeding.

• Control the pain by immersing the affected area in the hottest water tolerable without causing injury — the upper limit is 113°F (45°C) — for 30 to 90 minutes. Have someone test the water on the same area as the injury to ensure it is not too hot, as intense pain may impair one’s ability to discriminate between hot and scalding. Repeat as needed.

• Apply cold packs or ice later to reduce swelling and help with pain.

• Take pain control medication, if needed.

• Apply topical antibiotic, if available. include sedatives, a tetanus vaccination and antibiotics.

• If severe symptoms are present, call 911 or your local emergency medical services number.

• Call the DAN 24-hour emergency hotline at +1–919–684–9111.

COURTESY DARIO GOMEZ

STEPHEN FRINK

• Seek a professional medical evaluation; medical management may

victim’s skin, venom flows to the wound. Possible contact with various marine life occurs during diving, fishing and food handling. Even though most fish stings are benign, some lionfish stings require urgent medical treatment.

Puncture wounds by lionfish can cause pain lasting for several hours, rapid edema (swelling) and subcutaneous bleeding. Swelling typically clears in two to three days, while the tissue discolorations can last up to five days. In some cases swelling can become so severe that blood flow is compromised, possibly leading to tissue necrosis (tissue death), which can be common in fingertips. A secondary complication is wound infections. Lionfish venom is not lethal to healthy humans, and we are not aware of any published reports of death.

Envenomations are rare even in areas where lionfish are common, but recognition of the fish is important to prevent injuries. In Cozumel, we have gathered six years of data encompassing 107 cases for which we recorded the following symptoms in order of frequency: pain, erythema (redness), edema, local heat, blisters, necrosis (dead tissue), nausea, vomiting, dyspnea, fever and muscular weakness.

Limb paralysis and cardiac failure are infrequently observed.

We have recorded only two complications from lionfish envenomations: one due to thermal burn (and later

infection) when applying hot water to the sting area and one case of decompression sickness resulting from a diver reacting with a rapid ascent after being stung. The injuries we recorded did not pose risks of cardiovascular failure or death in our patients. The most important symptoms were the local inflammation and severe pain. We did not observe in our patients some signs and symptoms sometimes reported with lionfish envenomations; we recorded only four cases each of blisters and necrosis. In our opinion, most of the systemic signs we found were related to pain.

In the past two years we have seen a significant reduction in the number of lionfish envenomation victims seeking medical assistance, likely because people are now more familiar with lionfish and proper first aid for stings — and also because the park has reported fewer lionfish sightings after an intensive program to control them began five years ago. DAN has provided information about how to treat lionfish injuries, working in conjunction with Arrecifes de Cozumel National Park to distribute thousands of first-aid information cards over the past five years. Informed divers are able to reduce contact with lionfish and increase their ability to manage injuries when they occur. AD

ABOUT THE AUTHOR: Jorge Dario Gomez Castillo, M.D., is the DAN medical liaison in Mexico.

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BACK TO BASICS:

UNDERSTANDING DECOMPRESSION ILLNESS B Y

N I C H O LA S

B I R D,

M. D . ,

MM M

DECOMPRESSION ILLNESS IS A FASCINATING CONDITION that lurks in the shadows of divers’ minds, reminding us that we are vulnerable and that our push to explore is tempered by potential consequences. Whether ascending from depth or traveling to high altitudes, as we move outward and upward from Earth’s center, the ambient pressure decreases. Under the right circumstances this can initiate a complex interplay between physics and physiology that leads to injury.

Divers face two types of decompression-related injury: decompression sickness (DCS) and arterial gas embolism (AGE). Collectively, these conditions are often lumped together and referred to as decompression illness (DCI). Their common origin is the process of decompression, but their underlying causes differ significantly.

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AGE

AGE is the disabling injury in 29 percent of dive fatalities and is likely associated with insufficient gas supply, which is the trigger in about 41 percent of dive accidents.1 Emboli are actual or potential blockages of blood vessels by foreign material. They can be composed of gas, blood clots, fat, tumors, amniotic fluid or bacterial vegetations.

In the case of AGE in divers, the emboli are made up of gas in the arterial bloodstream resulting from lung overexpansion or pulmonary barotrauma (a physical injury to lung tissue resulting from pressure change). These injuries allow gas to escape from the small air sacs of the lungs (alveoli) and enter the arterial bloodstream.

Boyle’s law — which states the volume of a quantity of gas will increase as ambient pressure decreases — explains lung overexpansion on ascent. The reverse of this law is also true: The volume of a quantity of gas will decrease as ambient pressure increases with descent. Divers face the highest risk of pulmonary barotrauma in shallow water.

The greatest pressure differential experienced by divers in the water column (relative to the ambient pressure at the surface) occurs within the first 10 to 15 feet.

Expansion of gas beyond the point that the alveoli can accommodate it results in lung tissue damage and enables air trapped in the lungs to escape into the pulmonary veins, which return oxygenated blood to the heart. When this happens the escaped air can enter the heart and traverse to the brain, where acute neurological injury may occur. The speed with which this happens explains the rapid onset of symptoms following a dive — AGE occurs within minutes.

Pulmonary barotrauma can also manifest as free air in the mediastinum (an area in the chest between the lungs), which is known as pneumomediastinum, or it may

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manifest as a pneumothorax (air in the chest cavity outside the lungs). The greatest threat to divers is an AGE that reaches the brain, a condition known as cerebral arterial gas embolism (CAGE).

Symptoms of CAGE manifest at or near the surface immediately after a dive, and approximately 50 percent of divers who suffer CAGE experience sudden unconsciousness. Others may have acutely altered mental status or loss of coordination or strength, which are signs and symptoms of stroke and are the result of restricted blood flow to parts of the brain. Those who survive the initial injury may spontaneously revive within minutes, showing varying degrees of neurological injury or even a return to normal function.

Regardless of apparent normality, all victims of pulmonary barotrauma, AGE or CAGE should be evaluated urgently in a hospital emergency department.

Neurological symptom recurrence is known to happen in patients with apparent full recoveries. The consensus among hyperbaric physicians is that anyone who shows signs of neurological injury after a dive should be evaluated. People diagnosed with AGE should receive hyperbaric oxygen therapy (chamber treatment).

CT scans of the head are often part of these patients’ initial evaluation when they reach the emergency department. It is important to assess the existence of brain lesions or a stroke prior to initiating hyperbaric chamber treatment — not because hyperbaric treatment will worsen the condition but because bleeding in the brain requires immediate surgical intervention. Ruling out intracranial bleeds and blood clots, which can also cause acute neurological injury, is an important step; the absence of these factors supports the diagnosis of dive-related AGE and the use of hyperbaric oxygen therapy.

PHOTOS BY STEPHEN FRINK

From left: Although high bubble scores (as evaluated by ultrasound) are not diagnostic of DCS, they indicate considerable decompression stress and are correlated with DCS symptoms.

• Multiplace chambers enable accompaniment by medical staff, which is important for seriously injured people.

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DCS: BUBBLE TROUBLE

GAS LAWS RELEVANT TO UNDERSTANDING DCI Boyle’s Law: At a constant temperature, the volume of a given gas is inversely proportional to the ambient pressure.

To maintain a neutral lung volume as we descend on scuba, we inhale proportionally more gas molecules per breath.

Dalton’s Law: The total pressure exerted by a gas mixture is equal to the sum of the partial pressures of each individual gas in the mixture.

As we breathe more gas molecules per breath on descent, the potential impact of elevated partial pressures becomes important. Nitrogen narcosis results from an elevated partial pressure of nitrogen.

Henry’s Law: At a constant temperature, the amount of a given gas that dissolves into a liquid is directly proportional to the partial pressure of that gas above the liquid. In physiological terms, this gas pressure exists in our lungs relative to the gas pressure in our blood.

The greater the pressure of gas in our lungs, the more gas will dissolve into our blood and tissues.

This is the basis of decompression sickness.

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Pain

Constitutional

Mental status Pulmonary Coordination Consciousness Auditory Lymphatic Bladder, bowel Cardiovascular

40.8

13.6 6.1

Muscular weakness

Muscular discomfort

63.4

27.4

Dizziness/vertigo

Cutaneous

68.0

40.6

Numbness, paresthesia

Symptoms

DCS is associated with the absorption of inert gas (nitrogen or helium) into tissue coupled with an ascent to reduced ambient pressure, where the elimination of the gas may result in bubble formation. This promotes inflammation and tissue trauma.

Integral to understanding this disease are the gas laws of Boyle, Henry and Dalton. Boyle’s law explains why we must inhale progressively greater numbers of gas molecules per breath as we descend for our bodies to maintain pressure in our chest equal to that of the ambient environment. The increased number of gas molecules in our lungs relative to those in our blood and tissues creates a diffusion gradient, which, according to Henry’s law, drives the gas molecules into solution. Which and how many of these molecules we absorb is defined by Dalton’s law and is also influenced by differences in blood flow to different parts of our body.

The longer and deeper we dive, the more gas we absorb. When sufficient quantities of inert gas come out of solution and form bubbles during ascent, local

3.8

19.4 18.7

9.5 3.4 6.5 1.3 7.9 1.2 5.6 0.9 7.9 0.8 1.8 0.4 2.1 0.3 1.8 0.3 2.8 0.04 0.4 0.04

0

All symptoms First symptom 20

40 60 Occurence (% of patients)

80

100

Classification and frequency distribution of initial and eventual manifestations of decompression illness in 2,346 recreational diving accidents reported to Divers Alert Network from 1998 to 2004.

and systemic inflammatory and vascular reactions may ensue, potentially leading to a broad range of clinical manifestations. Unlike AGE, DCS bubbles exist primarily in the venous bloodstream and within tissues, and symptoms may not appear for several hours.

DCS is linked to an inert gas load (decompression stress) and the presence of bubbles in the bloodstream.

Although high bubble scores (as evaluated by ultrasound) are not diagnostic of DCS, they indicate considerable decompression stress and are more highly associated with the onset of DCS symptoms than lower scores. Symptom onset time is roughly correlated with inert gas load: Higher loads are associated with quicker onset and more rapid progression of symptoms. A fascinating aspect of DCS is that symptom onset often occurs well after bubbles are detectable. Thus, while bubble detection is an indicator of decompression stress, it is not a diagnostic criterion.

Current research in DCS is focused on biological markers that can be detected in the blood. Investigators are exploring the potential association between decompression stress and the presence of membrane microparticles (membranebound vesicles shed from a variety of cell types) in the blood. Microparticle levels increase in association with many physiological disease states as well as with the shearing stress caused by bubbles in the blood. The working hypothesis is that certain microparticles (possibly induced by inert gas bubbles) may initiate, be a marker of or contribute to the inflammatory response that leads to DCS. This investigation goes beyond the pure bubble model. While bubbles in the blood certainly play a key role in the development of DCS, their presence or absence doesn’t reliably predict DCS symptom onset. Investigating this process at the molecular level may teach us a great deal more about DCS, providing insights that we hope will improve the effectiveness of both prevention and treatment.

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S P E C I A L

E D I T I O N

STEPHEN FRINK

ISTOCKPHOTO.COM

Above: A chamber operator carefully monitors the patient, the pressure, the gas and the time as she administers hyperbaric treatment.

Above right: CT scans of the head are often part of the initial evaluation for patients exhibiting symptoms of AGE. Ruling out intracranial bleeds and blood clots takes precedence over treating DCI.

Fortunately, DCS occurs infrequently. Based on data DAN gathered through Project Dive Exploration, the overall incidence of DCS is two to four cases per 10,000 dives. This incidence rate drops to zero to two cases per 10,000 dives from warm-water resorts and liveaboards and rises to 10-12 cases per 10,000 dives in sample populations of deep technical dives in northern Scotland.

TREATMENT

Hyperbaric oxygen (HBO) is the definitive treatment for DCS and AGE. Prior to definitive care, breathing 100 percent oxygen can expedite inert-gas washout, reduce symptom severity and enhance treatment effectiveness.

The most common and accepted initial chamber treatment protocol is the U.S. Navy Treatment Table 6.

Depending on patient status, these treatments may be extended or repeated. DCI is treated with equal effectiveness in both monoplace and multiplace chambers.

Monoplace chambers treat one person at a time, and patients are unaccompanied by medical staff. Multiplace

chambers enable the simultaneous treatment of multiple patients and medical staff accompaniment, which is important for seriously injured people.

EVACUATION

Dive accidents can be frightening, and once DCI is suspected, many divers fail to consider alternative explanations for the symptoms. To ensure that other severe injuries, illnesses and conditions are considered, DAN recommends that injured divers seek medical evaluation at the nearest hospital or medical clinic. If DCI is indeed the diagnosis, the staff and, if necessary, DAN can initiate a timely transfer to an appropriate and available hyperbaric facility.

Dive accidents prompt many questions. After you have contacted local emergency medical services, contact the DAN Emergency Hotline at +1–919–684–9111, or encourage the treating facility to do so. DAN can provide pertinent medical information as well as assist with planning and coordinating an evacuation. AD

REFERENCE: 1. Denoble PJ, Caruso JL, et al. Common causes of open-circuit recreational diving fatalities. UHMS 2008; 35(6):393-406.

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WOMEN’S HEALTH & DIVING B Y

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B R I TTA N Y

T R O U T

AN D

L AN A

SO R R EL L ,

EM T ,

D M T

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WHEN IT COMES TO FITNESS FOR DIVING, the recommendations for male and female divers are largely the same: good exercise tolerance, a healthy weight and awareness of possible concerns related to medical conditions and medications. Regardless of sex, all divers should use appropriate thermal protection, remain hydrated, understand the diving environment and dive conservatively.

Men and women, however, are physically and physiologically different. With women representing about a third of the recreational diving population — in 2013

S P E C I A L

E D I T I O N

the Professional Association of Diving Instructors (PADI) reported its population of certified divers as 66 percent male and 34 percent female, and males represent 64 percent of insured DAN members1 — it is important to consider specific health concerns that female divers face.

THERMOREGULATION

For both men and women, body temperature is centrally controlled in the hypothalamus and is affected by factors such as body fat content, fat distribution and body surface-area-to-mass ratio. Hormonal differences may affect thermoregulation, but body composition and size typically drive responses to cold exposure. Total heat loss may be greater in women because they generally have higher surface-area-to-volume ratios and lower muscle mass compared with men (greater muscle mass is associated with greater metabolic heat production).

Some research suggests that women’s body temperature falls more rapidly during immersion in cold water while at rest. The bottom line is that every diver should wear a suit that fits well and keeps him or her warm — exposure protection helps compensate for any heat loss due to hormonal or anthropometric differences.

PHOTOS BY STEPHEN FRINK

MENSTRUATION

No evidence suggests that women who dive while menstruating are harassed or bitten by sharks more often.

However, anxiety, dizziness, feeling cold and the potential for panic may be exaggerated during menstruation or premenstrual syndrome (PMS). Temporary iron deficiency during menstruation may reduce exercise capacity, so women should be prepared to modify their diving behavior if necessary. Menstruation can trigger migraines, which are more common in women than men. Delay diving if migraine symptoms occur.

Research suggests there may be a slight increase in risk for decompression illness during the follicular stage of the menstrual cycle (the roughly two-week span preceding ovulation). Everyone should dive within established limits, DAN.ORG

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but women might consider reducing their diving exposure during the follicular stage by incorporating additional conservatism into their dive plan. Completely refraining from diving while menstruating is not necessary, but women should be aware of how PMS and menstruation affects them and whether emotional stress, irritability, cramping, headaches or associated symptoms might compromise dive safety.

ORAL CONTRACEPTIVES

COURTESY ABI SMIGEL MULLENS

Use of oral contraceptives (as well as a sedentary lifestyle and long-distance travel) may contribute to possible clot formation such as deep vein thrombosis. Research indicates that oral contraceptive pill (OCP) use can increase the risk of a thromboembolic event such as a pulmonary embolism, heart attack or stroke. A 1985 report showed that women who use OCPs and smoke more than 25 cigarettes per day have a 23-fold increased risk for a thromboembolic event compared with those who do not smoke.5 While a thromboembolic event may be at least somewhat manageable on dry land, it would be unmanageable in the water. Quitting smoking, exercising regularly and moving frequently during long trips can help minimize the risk of an emergency due to clot formation.

PREGNANCY

Not only should pregnant women refrain from diving, women who think they may be pregnant or are trying to become pregnant should likewise avoid it. For ethical reasons there has never been experimental research investigating the effects of diving on a fetus. The retrospective anecdotal data regarding pregnancy and diving shows there may be a risk to the fetus should a mother continue diving during pregnancy. A survey of 208 mothers who dived during pregnancy showed higher rates of low birth weight, birth defects, neonatal respiratory difficulties and other problems.2 Decompression studies conducted on sheep demonstrated that a fetus may develop bubbles before the mother displays clinical symptoms of decompression sickness.3,4 (Sheep studies are relevant because the placentas of sheep and humans are similar.) The fetus runs the potential risk of death because the fetal cardiovascular system has no effective filter. Therefore, any bubbles formed are likely to go directly to the brain and coronary arteries. All sheep studies showed very high rates of fetal loss. Although it is limited, the available data seem to suggest strongly that women should refrain from diving while pregnant or trying to conceive.

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As with scuba diving, the data on freediving and pregnancy are limited, with most data coming from Japanese ama divers and Korean haenyo divers. Freediving for pearls and abalone is a way of life for these divers, most of whom are women. Many ama divers continue to freedive well into pregnancy without many adverse effects, although profiles are modified based on gestation.

Conservative freediving during pregnancy may be considered a safe activity for enjoyment or relaxation (provided good maternal and fetal health), but it should not be considered an ideal form of exercise. DAN recommends that pregnant women consult their doctor before beginning any new exercise activity.

The recommendations regarding a return to diving after childbirth vary based on the type of delivery. After a normal vaginal delivery without complications, a woman can resume diving in about 21 days. This allows time for the cervix to close, which limits the risk of infection. An uncomplicated cesarean section generally means eight to 12 weeks of not diving to allow the mother to regain stamina and cardiovascular fitness. If a woman is put on bed rest due to complications, waiting more than 12 weeks is prudent because of deconditioning and loss of aerobic capacity and muscle mass. Following a miscarriage, a woman can return to diving when the physician releases her for full, unrestricted activity.

BREASTFEEDING

Diving is considered safe for mothers who are breastfeeding. Nitrogen does not accumulate in breast milk, so there is no risk of the baby absorbing dissolved nitrogen through breastfeeding. But diving can be dehydrating and may thus interfere with milk production, so appropriate hydration is important.

COSMETIC AND RECONSTRUCTIVE PROCEDURES

Fitness to dive following plastic surgery depends on the procedure. For instance, Botox injections, which relax facial muscles to reduce the appearance of wrinkles, typically require very little down time. Diving can be considered as soon as the treating physician feels there is no risk of infection. Dermal fillers warrant more consideration since they are designed to add volume to reduce the appearance of wrinkles. The concern is not the ambient pressure in the diving environment but rather displacement of the filler caused by pressure from the diver’s mask. The treating physician can offer advice on the time required for the displacement of fillers to no longer be a risk.

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Diving after major plastic surgery such as abdominoplasty (a “tummy tuck”) or breast implants is deemed safe once the treating physician has released the patient for full and unrestricted activity — six to eight weeks is typical for these types of procedures. Caution should be taken when diving with breast implants. Avoid constricting buoyancy compensator straps to prevent undue stress on the implants.

Keep in mind that saline implants are neutrally buoyant, but silicone is negatively buoyant and may alter a diver’s trim in the water.

AGING AND MENOPAUSE

E D I T I O N

in incorrect diagnoses and treatment delays. Cardiovascular disease can be misdiagnosed as dive-related illnesses, especially in women because of the increased incidence of ambiguous symptoms such as fatigue, malaise and/or flulike symptoms. In any emergency situation, timely first aid is critical, but quick and appropriate intervention in a diving context can be challenging.

OSTEOPOROSIS

Preventative health for women as they age includes awareness of the increased risk of osteoporosis, which can be determined by a bone density test. The National Osteoporosis Foundation recommends that women receive a bone density test if they meet any of the following criteria: they have broken a bone after age 50, they are of menopausal age with risk factors, they are under 65 years of age and postmenopausal with risk factors, or are 65 years of age or older. Compromised bone health is not a contraindication for diving, but women who have been diagnosed with osteoporosis or severe bone loss should consider avoiding wearing heavy dive gear such as tanks and weights while out of the water. Divers with osteoporosis should adapt their diving to reduce the risk of fractures and falls by putting on tanks in the water, avoiding carrying tanks on land and avoiding hazardous shore entries such as rocky beaches.

STEPHEN FRINK

The average age of the diving population is increasing.

According to DAN membership data from 2000 to 2006, the average age of male members was 44, the average age of female members was 42, and the average age of both sexes increased significantly over the four-year period.1 With aging comes special considerations for female divers. The symptoms of menopause can be both physical and emotional, including anxiety, decreased energy, hot flashes, sleep disruption and mood changes. Nonetheless, menopause is not a contraindication to diving, assuming symptoms do not compromise dive safety, nor is it the greatest risk for aging female divers.

Medical concerns associated with aging — such as hypertension, heart disease and diabetes — require greater attention, as they are more likely to affect diving.

Postmenopausal women are at increased risk of certain medical conditions such as cardiovascular disease, stroke and osteoporosis.

Hormone replacement therapy, which can be used to relieve some symptoms of menopause, may provide cardiovascular protection in younger menopausal women (age 50-54) but may increase the risk of plaque rupture in older menopausal women.

S P E C I A L

RELATIVE RISK

A comparison of fatality rates by age and sex of DAN members determined that men were 2.8 times more likely than women to die while diving.1 Some people might conclude this means men are more likely to engage in risky behaviors than women, but that would be speculation.

SUMMARY

CARDIOVASCULAR HEALTH

According to the American Heart Association, cardiovascular disease kills more women than all forms of cancer. DAN fatality reports show that cardiac incidents are among the top three disabling injuries in diving fatalities, regardless of sex.1,6 Signs and symptoms of a cardiac event can differ between women and men. Women are less likely to report chest pain during a heart attack, which may result

Male and female divers have more similarities than differences. To dive safely, both must be physically fit, competent and properly trained for the environment they dive in. But understanding health considerations of particular relevance to women, such as pregnancy, thermal regulation and the differences in symptoms of cardiovascular problems, is useful to all women who dive — and those who dive with them. AD

REFERENCES 1. Denoble PJ, Pollock NW, Vaithiyanathan P, Caruso JL, Dovenbarger JA, Vann RD. Scuba injury death rate among insured DAN members. Diving and Hyperb Med. 2008; 38(4):182-188. • 2. Bolton ME. Scuba diving and fetal well-being: A survey of 208 women. Undersea Biomed Res. 1980; 7(3):183-189. • 3. Fife WP, Simmang C, Kitzman JV. Susceptibility of fetal sheep to acute decompression sickness.

Undersea Biomed Res. 1978; 5(3):287-292. • 4. Powell MR, Smith MT. Fetal and maternal bubbles detected noninvasively in sheep and goats following hyperbaric decompression. Undersea Biomed Res. 1985; 12(1):59-67. • 5. Rosenberg L, Kaufman DW, Helmrich SP, et al. Myocardial infarction and cigarette smoking in women younger than 50 years of age. JAMA 1985; 253(20):2965-2969. • 6. Denoble PJ, Caruso JL, Dear GdL, Pieper CF, Vann RD. Common causes of open-circuit recreational diving fatalities. Undersea Hyperb Med. 2008; 35(6):393-406.

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STEPHEN FRINK

Opposite: Encounters with free-floating jellyfish larvae can cause itchy bumps.

• Vinegar can neutralize nematocysts to prevent further envenomation.

STEPHEN FRINK

Clockwise from left: Portuguese man-of-war, fire coral, box jellyfish.

K E LV I N A I T K E N / V W P I C S / A L A M Y

MARINE ENVENOMATIONS:

JELLYFISH AND HYDROID STINGS B Y J O S E P H B E C K E R , M. D . , A N D P A U L A U E R B A C H , M . D . ,

M. S .

SOME OF THE MOST BEAUTIFUL and seemingly harmless marine invertebrates are among the most hazardous. Snorkelers and divers may unintentionally come into contact with free-swimming jellyfish or touch hydrozoans such as fire coral while exploring reefs or wrecks.

Occasionally, people may be stung while handling or stepping on jellyfish that have washed ashore. Although many envenomations are mild, some marine invertebrates produce incredibly potent toxins that can cause serious medical complications and even death.

GENERAL TREATMENT PRINCIPLES The four main classes considered in this article are (1) hydrozoans, such as Portuguese man-of-war and fire coral; (2) scyphozoans, the true jellyfish; (3) anthozoans, including stony corals, soft corals and anemones; and (4) cubozoans, the box jellyfish, including Chironex fleckeri. Each of these classes is armed with stinging cells generally known as nematocysts. Symptoms of envenomation depend on the species, venom dose and body location. Immediately after a suspected jellyfish or hydroid sting, rinse the affected area with household vinegar (acetic acid 5 percent solution). If vinegar is not available, use seawater or a paste of baking soda. Hot water (to the victim’s and caregiver’s tolerance), heat packs, cold packs or ice may provide some pain relief, but do not place ice or unheated freshwater directly on affected skin. Remove any tentacle fragments, but take care to avoid contact with fingers or hands (wear thick gloves if possible). Rinse again with any remaining vinegar.

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BOX JELLYFISH STINGS The most well-known box jellyfish, Chironex fleckeri, is perhaps the most venomous creature in the sea and can cause death within minutes of envenomation. Although box jellyfish are most often found in quiet, protected and shallow areas — chiefly in the waters off northern Queensland, Australia — they may also be found in the open ocean. Death is attributed to shock, respiratory paralysis and subsequent cardiac arrest and may occur in 15-20 percent of cases. With any suspected box-jellyfish sting, the victim must be assessed rapidly for adequate breathing and supported as needed with artificial breathing and oxygen. The person should be moved as little as possible. The affected area should be immediately flooded with vinegar for at least 30 seconds and preferably a few minutes before any attempt is made to remove adherent tentacles; this can neutralize nematocysts somewhat and helps lessen the ultimate degree of envenomation. Severe pain and rapid development of wheals, blisters and reddishpurple tentacle markings are likely. In certain areas, such as Queensland, Australia, antivenin is available in hospitals and at some beaches, where lifeguards may be trained to administer it by intramuscular injection.

E D I T I O N

PHOTOS BY STEPHEN FRINK

Hydrocortisone (0.5 percent to 1 percent) cream or ointment may be applied twice daily to the affected area until signs and symptoms of envenomation disappear.

In some cases, a doctor may need to prescribe a stronger steroid regimen. If the area appears infected or the victim develops a fever, discontinue the use of any steroid and seek medical care. Complex or significant envenomations (any producing systemic symptoms such as nausea, vomiting, shortness of breath or confusion) require immediate evaluation by a physician.

After an envenomation it is possible for individuals to develop an allergic reaction, which may be severe.

Anaphylaxis is a potentially deadly allergic reaction that can involve respiratory distress, airway compromise and other unstable vital signs. If anaphylaxis occurs, immediately administer epinephrine with an EpiPen or Twinject auto injector, if available. Provide oxygen and the antihistamine diphenhydramine (Benadryl). All patients suspected of having a serious allergic reaction should be treated immediately by a physician, who may administer prednisone or other medications.

Safe Sea, a topical jellyfish-sting inhibitor, has been shown to effectively diminish or prevent certain jellyfish stings. Care should be taken when swimming or diving into jellyfish-infested waters. Protective clothing should be worn, and a wide berth should be given to all jellyfish because tentacles may trail for several meters behind the bell and main body of the organism. Gloves may help protect against hydroid and anemone stings.

S P E C I A L

PORTUGUESE MAN-OF-WAR The Portuguese man-of-war (Physalia physalis), known in the Pacific as the bluebottle, is not a true jellyfish but a colony of organisms. The man-of-war floats in the open ocean, typically in warm waters without any means of propulsion, relying solely on currents and winds. Man-ofwar stings usually cause severe pain, leaving whiplike red welts on the skin. Other reactions include fever, shock, cardiac and pulmonary failure and, in rare cases, death.

Although painful, man-of-war stings often resolve on their own. Affected areas should be rinsed with seawater (avoid freshwater). If symptoms persist, worsen or show no sign of improvement after several hours, or if there are any systemic symptoms such as fever, confusion, nausea or vomiting, seek care from a physician.

FIRE CORAL STING Fire corals are hydrozoans rather than true corals, although like corals, they are immobile. Fire corals have nematocysts but also have sharp edges that may cause lacerations or abrasions. Symptoms of fire-coral envenomation include immediate stinging and burning. A skin reaction, involving red wheals and blisters, may develop along with considerable itching. Fire-coral envenomations should be treated according to the general treatment principles described at the beginning of this article.

SEABATHER’S ERUPTION Seabather’s eruption is a skin irritation, mostly of covered areas of the body, caused by larval forms of certain sea anemones. Skin manifestations of seabather’s eruption may occur minutes to hours after swimming. The reaction typically involves red, burning, itchy bumps and/or hives that may persist for up to two weeks. Treatment consists of washing the affected areas with soap and water followed by a vigorous rinse. An initial brief soak with vinegar may help reduce symptoms.

Jellyfish and hydroid envenomations are frequently painful and may occasionally cause severe illness. Careful employment of the techniques above, as well as an effective evacuation plan and knowledge of local medical facilities and resources (including the availability of antivenin) can reduce pain and may be lifesaving. AD DAN.ORG

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W AY N E H A S S O N

CHILDREN AND DIVING W H AT A R E T H E R E A L C O N C E R N S ?

BY

M AT ÍAS

NOC H E TTO ,

M .D .

WHEN RECREATIONAL DIVING EQUIPMENT became commercially available in the 1950s, scuba was established as an exciting activity for courageous adepts all over the world. As equipment and confidence in technique evolved, diving became available to more people, including children.

Children and diving, however, is not without controversy. Concerns range from kids not having sufficient body size and strength to aid a fellow diver to the risk of inhibited bone growth and other medical concerns.

Children are not small adults. They are still growing, with different organs and systems developing at various speeds. They are maturing and evolving both physically and psychologically. Children are predisposed to ear infections as a consequence of their Eustachian tubes’ immature form and function, which may also increase their risk of middle-ear barotrauma.

Children burn lots of calories, and the resulting heat provides them with good tolerance to cold. Once the expendable calories are exhausted, however, without adequate thermal insulation children may be more prone to hypothermia, and their relatively high body-mass-tosurface-area ratio leads to accelerated heat loss.

Childhood asthma underscores how pulmonary function is still evolving in young people, and any risk of air trapping is a serious concern when breathing compressed gas.

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Perhaps the most significant concern about children and diving involves psychology and cognitive ability.

Children often lack the mental maturity to understand and manage invisible risks, and they can behave unpredictably in stressful circumstances. Adherence to plans can be a problem for those who are easily distracted.

Diving and dive training practices currently address the physical, physiological and psychological challenges inherent to children by adapting equipment, modifying techniques, limiting exposure and mandating strict supervision.

Data about diving injuries among children are very scarce. Limited statistics available through some training agencies do not provide any cause for alarm, and injuries reported through the DAN Emergency Hotline rarely involve children. Some dive instructors praise youngsters’ surprisingly good water skills; others argue that a single dive-related fatality in a child would be too many.

We ask the experts.

What risks concern you most when it comes to young divers?

Simon Mitchell: I am generally relaxed about diving by children provided there is strict adherence to the recommendatiaons around training, supervision and scope of diving promulgated by the major training

2 0 2 1

organizations. I think the biggest potential problems relate to emotional and behavioral immaturity in children that may lead them to make poor decisions or be inattentive to plans. This concern can be mitigated by appropriate supervision.

David Charash: In general the risks of diving include barotrauma, decompression sickness, arterial gas embolism, panic, drowning and traumatic events.

The risks of diving don’t discriminate based on age or experience. So the real questions are: • How well can an individual diver handle a given problem?

• Can the diver understand the level of risk present and decide on the degree of risk he or she is willing to accept?

• Can a child mitigate the risk by adjusting his or her dive profile?

Thomas March: By and large the pediatric population is quite healthy. We worry much more about mental errors that are unforgiving in scuba. The frontal lobe, which is associated with judgment, is generally not fully developed until the mid-20s. Panic, overconfidence and anxiety are serious concerns in the pediatric population. I also worry that many pediatric-age divers do not have the physical strength and/or skills to be a dive buddy responsible for the life of another diver.

David Wakely: Inexperienced adult divers are the greatest risk to children who dive. A child diver has a very different mindset from that of an experienced adult.

Adults who think the child they are diving with is capable of all conditions and scenarios, who jump in the water beside the child but do not really watch them closely, are dangerous buddies for a child to have.

A child should always be paired with an adult who has the experience to deal with the child’s short attention span and tendency to be distracted by shiny objects. The adult should constantly monitor the child’s air and depth, swimming position and rate of ascent or descent.

Do you think that limiting the exposure makes diving safer for children?

Mitchell: Limiting depth/time exposures makes diving safer for adults and children. It is one of a number of pragmatic ways of mitigating the possibility that children may be more prone to events such as running out of air and rapid ascent. It clearly does not affect the risk of some diving problems such as barotraumas.

Charash: Intuitively, placing a clear and defined limit on depth and time of exposure is likely to add an additional layer of safety in children, but we must not forget that there is risk at any depth and dive time.

S P E C I A L

E D I T I O N

March: Turning loose young divers with compressed air even in shallow depths may be a big mistake. In my opinion it’s more important that the instructor has the skills to assess a young diver’s ability to be mentored.

Stratification based on skills and experience — as seen in martial arts training, for example — could be useful.

Many young divers are eventually able to appreciate the risks, but readiness can vary dramatically and depends much less on age than maturity. I think efforts to credential specialized instructors might be worthwhile.

Wakely: A graduated response to learning and freedom to dive is essential for child safety. I like to use the analogy of skiing — it’s a potentially dangerous sport, but there are few adults who argue that children shouldn’t be skiing. It’s widely accepted that children should start on gentle slopes, wear a helmet and gradually move up to more advanced terrain according to their abilities.

Is decompression stress a concern with regard to long bone development in children?

Mitchell: There is no evidence for it. The epiphyseal plates of the long bones do not close until late adolescence, and there has been extensive diving by teenagers for decades. Despite this, I am unaware of a single case of apparent growth inhibition in a limb as a result of decompression sickness in a teenager.

Charash: There are no studies that show clear evidence that diving (decompression stress) can affect long bone development in young divers. What is not so clear is the effect of microbubbles that may enter the circulation and possibly affect the blood vessels in the growth plates (epiphyseal plates). I suggest limiting children’s exposure to nitrogen by restricting depth and dive time and increasing surface interval time.

March: We know that tissue perfusion in the growth plates is significantly different from that in most other body compartments. This is clear because we find pediatric patients much more susceptible to bloodstream infections in these areas. The standard gas-compartment models are likely inadequate as routine dive tables, and experimental confirmation is neither ethical nor practical. The general consensus of a margin of safety seems prudent.

Wakely: There is no evidence that the hyperbaric environment has any ill effect on growing bones. The Undersea and Hyperbaric Medical Society (UHMS) lists 14 medical conditions that are known to benefit from hyperbaric oxygen therapy (HBOT). For two of these conditions, osteomyelitis (long-term bone infection) and osteoradionecrosis (bone damaged by radiation therapy), DAN.ORG

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the HBOT addresses the underlying problem (infection and dead bone), encourages new blood vessels to form in the bone and allows the bone to heal itself. HBOT has no known negative effect on healthy bone of any age.

Do you think 10-year-olds have the mental maturity to understand and manage the invisible risks involved in scuba diving?

MEET THE EXPERTS David Charash, D.O., CWS, FACEP, UHM, is medical director of wound care and hyperbaric medicine at Danbury Hospital in Connecticut. He is a certified diving medical examiner as well as a DAN Referral Physician and DAN Instructor. Dr. Charash lectures locally and nationally on dive safety and dive medicine.

Thomas March, M.D., a practicing pediatrician for 30 years, has a special interest in developmentally and behaviorally challenged pediatric patients. A diver for more than 35 years, he has special training and interest in administrative medicine and fitness-to-dive evaluations.

Simon Mitchell, MB, ChB, Ph.D., FUHM, FANZCA, is a physician who is widely published

Mitchell: The question requires context. Within the framework of a dive training program and guidelines of practice designed specifically for this age group, my answer would be “yes, in most cases.” Put another way, if the supervision and depth/time recommendations for diving are adhered to, then most properly motivated 10-year-olds should be fine. But if the question is whether a 10-year-old should be considered an independent open-water diver (as we understand that concept in adults), then my answer would be no.

Charash: To answer this question it is important to understand normal childhood growth and development. As there is significant variation in maturity and development, it is not possible to predict who will have the capacity to understand and also manage risk. Specific to the question, it would be a challenge to expect a 10-year-old to understand “invisible risk.”

March: Many 10-year-olds may be capable, but many more may not be. Unfortunately there are often incentives for instructors, parents and even dive operations to train unready students. Adults who have the skills to assess the readiness of pediatric-age divers can facilitate positive and acceptably safe in-water experiences for kids of any skill level.

Prioritizing positive experiences for pediatric-age students allows for better advancement of all skill levels and avoids the all-or-none dichotomy of certification-focused programs.

This also prevents a sense of failure for students unable to complete certification and may relieve some of the pressure parents place on instructors to certify students.

in his specialist fields of anesthesiology and dive medicine. Head of the department of anesthesiology at the University of Auckland, he is an avid technical diver, a Fellow of the Explorers Club and the 2015 DAN/Rolex Diver of the Year.

Margo Peyton, MSDT, is a scuba educator, member of the Women Divers Hall of Fame and the founder and director of Kids Sea Camp, through which more than 5,900 young people have learned to dive. Each year roughly 1,2001,600 students dive with Kids Sea Camp, which has a perfect safety record.

David Wakely, FRCEM, FRCS, MBBS, BSc, Dip IMC, EDTC-II, is a consultant in emergency

Wakely: Every child differs, but between the ages of 7 and 11 children’s cognitive abilities change in two ways.

First, concrete thinking occurs. This is the ability to solve logical problems that apply to actual objects or events. Second, children become less egocentric and develop the ability to view things from others’ perspectives.

So the average 10-year-old should have the mental maturity to understand the concept of risk and be able to solve concrete gear-related problems. However, the formal operational stage of thinking — using abstract thought and applying it to problems that have not even occurred yet — does not manifest in most children until ages 11 to 15. The major dive training agencies’ programs for young divers do a good job of reflecting these stages of cognitive development.

medicine as well as wound care and hyperbaric medicine at the King Edward VII Memorial Hospital in Bermuda. He also is a dive medicine consultant for the Bermuda police and government and a dive instructor who works extensively with children.

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What characteristics do you consider necessary for a child to be a good candidate for scuba diving?

Mitchell: The most important thing is that the child wants to dive. It is also vitally important that the parents are supportive and wholly involved in the decision to allow diving, acting as informed risk-acceptors on the child’s

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behalf. The child should exhibit a level of emotional, intellectual and physical maturity compatible with the scope of diving prescribed for his age group. Note that these characteristics cannot be adequately assessed in an office-based consultation. Thus, the evaluation of a child’s suitability for diving is substantially the responsibility of the diving instructor who sees the child perform in the water, rather than the doctor.

Charash: There are five components that suggest that a given child is a good candidate for scuba: medical fitness (absence of any medical condition that could affect safety), psychological fitness (appropriate motivation for diving and achievement of relevant developmental milestones), physical fitness (capability to manage equipment and swim against a current), knowledge (knowing how to respond to situations appropriately) and skills (ability to clear a mask, buddy breathe, etc.).

March: Demonstrated surface skills such as breathing through a snorkel without anxiety are minimal requirements for undertaking instruction. Poor attention span, overconfidence and anxiety would seem to be exclusionary criteria. Pediatric patients do well with incrementally increasing responsibility. Unfortunately age alone is not a good indicator of developmental capabilities, and tailoring advancement based on the individual’s readiness requires skills on the part of the instructor and mentors. As we consider the potential risks and harm that can be done, we must also balance this with the opportunities for enriching the appreciation of the underwater world and developing confidence and skills in our future generations of divers Wakely: Several factors should be considered when assessing a child scuba student.

Psychological maturity: Candidates should be calm and rational, not prone to extreme emotional outbursts and not prone to anxiety in unfamiliar situations. They need to understand risk and risk avoidance.

Educational maturity: The child should be able to learn independently. Learning scuba theory is a big undertaking, and the students must be able to concentrate on the material and know when to ask questions. They should be able to understand what they are reading enough to apply the principles described to situations they see around them in daily life.

Physical maturity: The child should be able to swim and should be very comfortable in and around water.

Currently dive equipment for very small children is hard

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to find, so the child should be physically large enough to wear the available gear correctly and safely.

Desire to dive: The desire to dive must come from the child, not the parent. A dad asking an instructor to teach his son is very different from a child who wants to learn to dive like his dad.

Medically fit: Asthma, ADHD and morbid obesity are prevalent today, and these three conditions commonly disqualify children from diving. If you are considering arranging for your child to learn to dive, discuss your plans with a doctor familiar with dive medicine.

What has been your biggest challenge in training young divers?

Margo Peyton: My biggest job is educating parents.

Parents frequently fail to disclose important information on medical forms because they worry their child will be prevented from diving. Full disclosure of all medical conditions is crucial — not only to maximize the child’s safety but also so the dive operator can accommodate any special needs the child may have.

For example, we once had a child with autism in our program and were unaware of his condition until he panicked during his first open-water dive. He became very agitated and aggressive. Thankfully no one was hurt, but the child had to be removed from the program, which was humiliating for him. Had we known about his autism we would have provided him with his own private instructor who had experience teaching children with autism.

Parents should be aware, however, that not all dive operators have experience working with children.

Adequate oversight should not be taken for granted. I recommend that parents ask dive operators the following questions before their children go diving: • Is a first aid kit and oxygen unit on board or nearby?

• Is a radio or cell phone available?

• Are all staff divers current and active divemasters or instructors? (Don’t hesitate to ask to see their C-cards.)

• What are the depths and conditions of the dives? (Make sure the child won’t be diving deeper than what is recommended for his or her age.)

• Do any of the instructors have training or experience working with kids?

• Does the boat have a safety tank, dropline and dive flag on board?

Parents should request a refresher course for children who have not been diving in 12 months, and they should not hesitate to ask that a divemaster accompany them if they aren’t comfortable diving alone with their child. AD DAN.ORG

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Climbing a ladder while wearing heavy gear, for example, can cause pain, soreness and even numbness or tingling that might be confused for DCS. However, symptoms after a dive warrant prompt administration of oxygen and evaluation by a medical professional.

Some things about this diver’s symptoms and recent history suggest DCS, and most doctors would include it on their list of differential diagnoses. The evaluating physician in this case considered it, but he knew that other potential causes had to be eliminated first. After a cardiovascular emergency was ruled out, blood tests and ultrasound imaging of the diver’s abdomen revealed stones in the gallbladder that were causing acute inflammation. The diver underwent laparoscopic surgery and made a successful recovery.

SYMPTOMS OF DCS

Books and articles about DCS usually include an extensive list of signs and symptoms. It is important to remember that none of the signs and symptoms in any such list is exclusive to DCS. Here are examples of some of the most common symptoms of DCS:

STEPHEN FRINK

UNCERTAINTY AFTER DIVING MART Y

MCC A F F E R TY ,

E M T- P ,

D MT

A 53-YEAR-OLD MAN WAS DIVING at a resort in the South Pacific. He was doing approximately four dives per day; all his dives were on air, and all were within his computer’s no-decompression limits. In the evening on the third day, approximately three hours after his last dive and a half hour after dinner, he began to experience severe abdominal pain. The pain radiated to his back, just below his right shoulder blade. He vomited several times, felt weak and needed help walking. Concerned about the possibility of severe decompression sickness (DCS), his friends called a taxi and rode with him to the local hospital.

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As you can see, these symptoms can apply to a wide range of medical conditions, not just DCS. This can make diagnosing DCS a challenge.

MEDICATIONS

C A S E R E P O RT S A N D R E C O M M E N D AT I O N S BY

• headache • lightheadedness and/or dizziness • nausea • joint and/or muscle aches • fatigue, lethargy and/or generalized weakness

A 48-year-old woman completed a dive to 95 feet for 25 minutes on 32 percent nitrox. Approximately 10 hours after surfacing she began to experience widespread but intense muscle pain. She could not find a comfortable position, and nothing seemed to offer relief. She called emergency medical services (EMS), which transported her to the local hospital. When discussing her medical history, the doctor found out that the woman had begun taking a statin medication to lower her cholesterol three weeks earlier. Muscle pain is a

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rare side effect of statins, and blood test results suggested that her pain was most likely due to the medication.

However, the hyperbaric physician who was consulted did not want to dismiss the possibility of DCS and treated the diver in the chamber with a U.S. Navy Treatment Table 6 (TT6). The hyperbaric treatment had no effect on her symptoms, which confirmed that the muscle pain was probably due to the medication.

Whenever you begin taking a medication, whether prescription or over-the-counter, make sure you familiarize yourself with the potential side effects. As this case illustrated, the side effects of some medications can mimic DCS. Medications can also affect your ability to function normally, regardless of whether you’re on land or underwater. Common seasickness medications, for example, come with advisories stating that they may cause drowsiness. Physicians trained in dive medicine typically recommend waiting at least 30 days after starting a new prescription medication before diving. Similarly, divers should always try nonprescription medications well in advance of diving so they will know how the drugs affect them. In addition to limiting the risk of disorienting or otherwise hazardous side effects at depth, this recommendation also helps reduce the risk of confusing the medication’s side effects with DCS. MUSCULOSKELETAL SYMPTOMS

Diagnosing DCS can be challenging: It is a relatively rare condition, there are no lab tests to confirm it or rule it out, and it shares signs and symptoms with many other illnesses and injuries. Divers who have pre-existing musculoskeletal issues such as spinal problems, arthritis or residual effects from previous trauma can be particularly susceptible to diagnostic uncertainty. The physical stresses and activities associated with diving and travel (e.g., carrying heavy equipment, enduring uncomfortable sleeping or travel accommodations, swimming against currents or experiencing boat rides in rough seas) can aggravate existing conditions. Strains, sprains and overuse injuries that occur in the absence of diving are relatively easy to diagnose.

But when diving is involved, a doctor might reasonably decide to conduct a costly and time-consuming hyperbaric chamber treatment to be on the safe side.

Musculoskeletal problems, whether pre-existing or not, can manifest as pain, numbness, loss of strength and/ or reduction of mobility, all of which are also possible symptoms of DCS. The key to learning the true cause of such symptoms is a thorough review of the diver’s medical history and the circumstances surrounding the complaints.

DAN Medical Services often receives calls from divers who have traveled to tropical or subtropical destinations and are experiencing a severe headache, multiple joint or muscle aches, abdominal pain, nausea and general malaise,

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often after a few days of diving. With no additional information it would be easy to conclude that these symptoms were the result of DCS. However, further inquiry often reveals a fever and diarrhea. This suggests a tropical disease rather than DCS. When such reports include a fever but not vomiting or diarrhea, this suggests dengue or another tropical virus. People with these symptoms may require prompt medical attention but not evacuation to a recompression facility.

DIAGNOSIS BY EXCLUSION

Diagnosing DCS is generally a process of ruling out other causes. It is imperative that we not discount the possibility of nondiving-related injuries or illnesses just because someone was diving. However, this is not to suggest we should discount the risk of DCS: When a person has been diving, DCS absolutely needs to be considered in the physician’s differential diagnosis.

A 46-year-old male diver on a weeklong dive trip on a liveaboard vessel was doing four or five dives per day. All dives were within recommended recreational no-decompression limits. His deepest dive was to 115 feet, which was his first dive on the third day. The next morning he complained of right shoulder discomfort. Five years earlier he had surgery on that shoulder to repair a torn rotator cuff. Since the surgery five years prior he had done more than 80 dives with no problems, but it was not uncommon for him to experience discomfort in that shoulder with exertion or certain activities. Usually he could find a position of comfort, apply ice and take ibuprofen to relieve the discomfort, but this time the symptoms were somewhat different and not as easily relieved.

The diver’s companions believed that his symptoms were due to his previous medical history because they had all dived the same profile without any problems. When the diver finally reported his symptoms to the boat crew, they provided him with high-flow oxygen. Based on the fact that the symptoms were different from those the man typically experienced, the captain diverted the ship toward an island with a dive clinic.

After breathing oxygen for approximately 30 minutes, the diver reported some improvement but not much. The ship arrived at the island 30 minutes later, and the diver was taken to the clinic. The physician on duty evaluated him and discovered that his right arm (his dominant arm) was significantly weaker than his left. He diagnosed DCS and treated the diver with a U.S. Navy TT6, which provided measurable improvement. Because the symptoms did not completely resolve, the doctor treated him again the next day with the shorter U.S. Navy TT5, which brought complete resolution of the symptoms.

There is controversy regarding the potential for increased risk of DCS at the site of a previous injury. Little scientific DAN.ORG

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THE MORNING AFTER

A group of friends in their early 30s was on a dive vacation on a Caribbean island. They did four dives on their first day; their first dive was to 85 feet, and the next three were to 60 feet or shallower. They waited at least an hour between each dive, breathed air and had bottom times that were all within their dive computers’ no-decompression limits. All dives were uneventful.

The group went out for dinner and drinks that evening.

The next morning they met for breakfast prior to boarding the dive boat. A 33-year-old male member of the group was absent. His roommate reported that when he left, the friend was in the bathroom and was expected to join the group later. After eating, the roommate and two others went to check on their friend. He was in bed and appeared pale.

He complained of a severe headache, nausea, weakness and feeling “totally out of it.” The headache was severe enough that he was sensitive to light. He also reported vomiting “once or twice.” The group decided to take him to be evaluated at the local clinic; because they had been diving they were concerned about DCS. The diver had a slight stagger when walking but required no assistance.

The clinic was a five-minute cab ride away from the resort. The physician on duty and her assistant obtained the diver’s vital signs and conducted a neurological examination. The physician also obtained a history of events. The diver denied any symptoms prior to going out for the evening. He also admitted that the events following dinner were not clear to him because he had consumed “a lot” of alcohol, which his friends confirmed. The physician ordered the administration of IV fluids, acetaminophen and meclizine (antinausea medication). The doctor also instructed the man to avoid diving for the next 24 hours and to return to the clinic if he didn’t feel better that day.

E D I T I O N

Fatigue after diving is not uncommon, but significant fatigue may be a sign of DCS.

The diver rested and was able to eat and drink (nonalcoholic beverages) over the course of the day, and he felt much better by that evening. The next morning he was feeling 100 percent better and resumed diving with no further issues.

Having a good time on vacation is part of the experience, but overindulging in alcohol during a dive vacation is not prudent. There is suspicion that alcohol consumption before or after diving could contribute to DCS, but more importantly, the aftereffects can easily be confused with DCS. Many divers in similar situations have needlessly undergone hyperbaric treatments.

CONCLUSION

The signs and symptoms of DCS are not exclusive to that condition. However, when a person experiences signs or symptoms after diving, DCS is very often presumed to be the diagnosis. This is not all bad, because it encourages divers and dive staff to administer oxygen and ensure the injured diver gets prompt medical care. But it becomes a problem when divers refuse to accept alternative explanations and become fixated on the need for chamber therapy at the expense of other diagnostics and/or treatments that may be delayed.

In addition, the diversion of a nondiving-related emergency from appropriate medical treatment for an unnecessary recompression treatment, especially by air late at night, can introduce additional risks to the patient as well as the aircrew.

There are many medical conditions much more serious than DCS for which timely treatment is critical.

In the event of symptoms after diving, provide oxygen and get the injured diver to the closest medical facility.

Don’t hesitate to call EMS if the situation is serious, and feel free to call the DAN Emergency Hotline (+1–919– 684–9111) at any time. Tell the doctor that the person was diving, and encourage him or her to contact DAN for consultation. But keep in mind that there are more dangerous ailments than DCS, some of which must be considered first. AD

LEARN MORE: For more information about the causes, mechanisms, manifestations, management and prevention of DCS, consult DAN’s Health and Diving Reference Series, available at DAN.org/health-medicine/health-resources/.

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STEPHEN FRINK

data addressing that issue is available. But controversy notwithstanding, we know that when people with preexisting musculoskeletal problems choose to dive, diagnostic confusion can result. If you or your dive buddy has such issues, it is imperative for both of you to know what the other person’s usual state looks like. Before diving, discuss any existing pain, movement restrictions, weakness or other information that establishes a clear baseline. Communicating information about a diver’s normal state can be of great value. Any variation of symptoms from previous experience demands assessment but does not by itself constitute a definitive diagnosis. Divers with these sorts of problems should regularly get a detailed neuromuscular exam by a doctor. After a dive is no time to discover a deficit that may or may not have been there before.

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MEMBERSHIP AND INSURANCE 36 A Culture of Dive Safety 39 Pneumonia in Germany 40 More Than Just Bubbles 42 Timeline of an Emergency Call 44 Touch and Go in Tonga 46 Professional Liability: Not Just for Pros 50 Divers Losing Access to Emergency Care 54 DCS in Cozumel 56 Reduce Your Liability Risk

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MEMBERSHIP & INSURANCE

A CULTURE OF DIVE SAFETY B Y

P E TA R

D E N O B LE,

M . D . ,

D . S C .

ESTABLISHING A CULTURE OF DIVE SAFETY is central to the mission of Divers Alert Network. Such a culture requires collective effort, and DAN intends to promote a discussion with the recreational diving community at large to advance safety and improve the diving experience.

The mantra of individual responsibility seems to ignore the very real social context of diving, a sport that is rarely practiced alone. In addition to one’s fellow divers, a dive incident may involve training agencies, dive operators, dive resorts, travel agencies, dive shops, medical and scientific organizations, equipment manufacturers and/or the media. Most incidents are attributed to human error, and calls to raise individual awareness are the remedies most often suggested by those concerned with safety.

While individual errors are a perennial issue in dive safety, it is also important to consider the role of social context in diving accidents and to promote appropriate social interventions, which may be more effective than interventions focusing exclusively on individual divers. To promote dive safety, we need to review the current safety culture (or lack thereof ) in recreational diving as well as the role of individual divers and other constituents of the diving community.

We ask you to participate in this effort and provide your view of what constitutes a culture of dive safety. DAN will take this conversation to dive shows, meetings and social media, but we intend to initiate the dialogue in this column. To do so we invited three distinguished, independent dive leaders to provide their insights.

“Most incidents are attributed to human error, and calls to raise individual awareness are the remedies most often suggested by those concerned with safety.”

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What does “recreational diving culture” mean to you?

Jill Heinerth: Sport diving is a community made up of many different subcultures.

These small groups of divers are knitted together by their shops, clubs, charter operators or perhaps agency affiliations. Some of these tribes are known for their technical expertise, their great trips or safe operations. Others are tagged for aggression, cockiness or exclusivity. If you’ve been diving long enough, you’ll find that people drift in and out, switch sides and change their behaviors. Sometimes

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change is brought on by the wisdom of experience, sometimes through the example of great leadership and other times influenced by the shocking impact of witnessing an incident or tragedy.

John Lippmann: The diving culture can create unlikely friendships between individuals who lead totally different lives and would otherwise have little opportunity or interest in interacting. Such friendships can become strong through the trust and varying levels of reliance that can develop between dive buddies. However, as with many of such groups, cliques can develop. These are sometimes necessary for group focus, but they can also be divisive.

Alessandro Marroni: I strongly believe recreational diving culture means awareness, education, common sense and respect for the underwater realm as well as for the fellow divers. Unfortunately, achieving these ends requires characteristics that are ingrained in divers through their cultures and experiences on the one hand and on the other hand acquired through study, attention, and the learned ability to evaluate and prevent risk. The first thing to be aware of is that diving takes place in the water, in which we humans would not survive unless we adopted special measures and acted not only with passion and curiosity but also with competence and prudence.

What are characteristics of a safety-aware diver?

Marroni: Safe divers have the same passion to understand the safety limitations of diving as they do for underwater photography, fish-watching or the simple enjoyment of exploration. They also remain aware of other divers, including their needs and the possible risks they represent. Much too often poorly arranged buddy teams or diving groups can lead to catastrophic events that could easily have been prevented by more careful selection and predive checks.

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rescue if needed?” A safe diver would enter the water only if each answer was an unequivocal “yes.”

What is the role of training agencies in shaping and disseminating a culture of safety?

Lippmann: Under their certification umbrella, they have the greatest influence on dive professionals. It is important that the agencies make their instructors and divemasters champions of dive safety, monitor their work and provide appropriate support in implementing the culture of safety. Those instructors who significantly or repeatedly breach reasonable safety standards need to be sanctioned appropriately.

The PADI “Responsible Diver” Campaign and the campaign to educate divers to ascend slowly and do safety stops are great examples of the important role that agencies can play in educating divers about key safety issues.

Heinerth: Training agencies have the opportunity to set the ground rules right from the beginning and guide divers to recognize that the general safety rules have been developed from practical experiences. One instructor who slips through the cracks without following standards can affect hundreds of future divers, who can also move on to affect another generation of divers. Maintaining high standards is critical to nurturing a consistent climate of safe diving practices.

Marroni: The commercial need to ensure expansion for the recreational diving industry has at times promoted misconceptions that activities in and under the water present little or no risk. I believe training agencies may be pivotal in producing changes by introducing the hazard identification and risk assessment (HIRA) components into their training programs to increase both the safety and the appeal of the sport.

Lippmann: A “safety-aware” (or more appropriately termed “safety-prepared”) diver would generally possess a variety of traits. These include a strong sense of self-preservation and self-responsibility, keenness to learn about pertinent risks and an awareness of his or her own physical, mental and medical health. Such divers seek relevant information about the site and potential associated hazards and are also prepared to abort a dive if necessary without being swayed by peer group pressure to take unacceptable risks.

How can dive operators contribute to the culture of dive safety?

Heinerth: These days operators are under increased competition to offer the best adrenaline-laced experiences. But I learned early that enthusiasm is infectious. If you love what you are doing, then your clients will love their experiences with you. There is wonder and satisfaction just being underwater. It’s great if you get blessed with a view of stunning manta ray, but it can be just as exciting to see a jawfish with a mouthful of eggs. Dive satisfaction doesn’t require great depths or unnecessary risks.

Heinerth: In my opinion, a safety-aware diver is one who is fully engaged in his or her participation in diving. A safety-aware diver is one who looks at a given dive and asks: “Am I fully capable of self-rescue in this scenario, and am I fully capable and willing to execute a buddy

Marroni: Many dive operators are not aware of the risks involved or their responsibilities toward their clients. They may not pay enough attention to their clients’ skills or fitness levels, environmental and technical safety, dive boat safety, tank refill stations, etc.

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Lippmann: Dive operators have the obligation to ensure that their equipment is well-maintained, that their staff members are well informed, competent and vigilant, and that divers are well matched for the sites they dive. If we don’t receive a sufficiently safe level of service from the dive operators we pay to dive, we should have little hesitation to look elsewhere.

MEET THE EXPERTS Jill Heinerth, a pioneering underwater explorer and filmmaker, has dived deeper into caves than any woman in history. To recognize a lifetime devoted to water advocacy, she was awarded the Wyland Icon and Sea Hero of the Year awards.

In recognition of lifetime achievement, the

How can the culture of dive safety be promoted?

Lippmann: Incident reporting and analysis provide strong tools on which to base relevant accident-prevention protocols.

DAN has a key role to play here, and the diving community is better served if it helps DAN collect information on diving incidents and accidents so they can help guide training strategies and diving practices. Unfortunately, in some places there is a tendency to withhold important information about accidents for fear of legal or commercial repercussions. It would be great if this would change.

Royal Canadian Geographical Society presented Heinerth with the inaugural Medal for Exploration.

Her photography and writing have been featured in prominent publications around the world.

John Lippmann is the founder of DAN AsiaPacific (DAN AP), which he established in 1994 to improve the safety of scuba diving within the Asia-Pacific. He was chairman, executive director and director of training for DAN AP for 20 years, the editor of Alert Diver Asia-Pacific for

Heinerth: As a young diver in Tobermory, Canada, I took a class from a great role model named Dale McKnight. Our class worked hard for days, practiced skills and made plans to go on the deepest dive (and first decompression dive) of our lives. We were on the boat heading to the site when Dale told us that we had done such a great job that he would reward us with an extra 10 feet of depth and five more minutes of bottom time. My colleagues hooted and hollered in excitement, while I felt a deepening anxiety. With my head bowed, I quietly muttered that I did not feel ready and would sit on the boat. I was disappointed and embarrassed. Dale tried unsuccessfully to reel me back into the dive.

After a few minutes, Dale admonished the other divers for permitting him to shift a safe, organized plan into a “trust-me” dive. At first I did not understand what was happening, but I soon recognized that he was patting me on the back. I had passed his test. He taught me an important lesson: A true survivor needs to know when to be willing to turn back and call it a day.

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of research at DAN AP. An internationally recognized dive-safety expert, he has written many books and articles about dive safety. In 2007 Lippmann received an Order of Australia award for services to scuba-diving safety, resuscitation and first aid.

Alessandro Marroni, M.D., is the founder and president of DAN Europe and chairman of International DAN. He is also vice president of the European Committee for Hyperbaric Medicine (ECHM) and a lecturer and professor of hyperbaric medicine at the Universities of Belgrade, Padova, Palermo and Pisa. Marroni is the author of more than 250 scientific papers and publications on underwater and hyperbaric medicine and has been a scuba instructor since 1966.

STEPHEN FRINK

Marroni: We can promote a culture of dive safety by transmitting love for the underwater realm while at the same time clearly explaining that the marvels of the sea do not come cheap but rather require certain basic but strict rules that help us avoid being overwhelmed by the force of natural elements.

We should spread similar messages in every course, before every dive and through every article or documentary related to diving. It is important to avoid indulging the superficial messages about the ease of diving or the misinformed, overly catastrophic “scoops” following dive injuries or fatalities. DAN has been striving to do so over the past 30 years, and I think that the results prove the efficacy of this approach. AD

13 years and is currently chairman and director

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PNEUMONIA IN GERMANY BY

G E O R G E

LE W B E L

underwriter took only two days...”

and together we called the primary insurer again.

Shortly after that call, the primary insurer finally paid its fair share of our claim for emergency medical services.

Before DAN got involved, the primary insurer had successfully stalled the claim. I was about ready to give up, but the people I spoke to at DAN reassured me that they would work with the primary carrier to get our claim paid. DAN’s Annual Travel Insurance is secondary insurance, so getting our primary insurer to meet its obligations was in DAN’s interest as well as ours.

The difference in the time that it took the two insurers to process the claim was striking, too.

Our primary insurer took about three months to reimburse us for its share. By comparison, DAN’s travel insurance program underwriter took only two days to process and approve our claim for the remaining 20 percent of the medical expenses. We received a check from them within a week.

Another lesson we learned from this experience was that having a backup high-limit credit card with a low current balance during an overseas trip may be really helpful. The German hospital told me they did not deal with foreign insurance companies — too much hassle — and they would not even see Nancy in the ER until they had run a charge of 500 euros on our card. I suspect that in less-developed countries, that’s even more likely to be the case. AD

ISTOCKPHOTO

FOR HE PAST FEW YEARS MY WIFE, NANCY, and I have purchased DAN Annual Travel Insurance policies. We both have primary medical insurance that is supposed to provide coverage for medical emergencies overseas.

While we were in Germany visiting friends, Nancy caught pneumonia and was hospitalized. I had to use my credit card to pay for the emergency room that admitted her as an inpatient, and the next day I had to pay an estimated cost for her entire stay.

I called the DAN emergency hotline via Skype the day after she went into the hospital, and DAN’s travel insurance carrier offered to fly a nurse to Munich who could accompany us on a flight home, if necessary. The insurers also offered to arrange and pay for the return flight. Fortunately, the hospital was excellent, and Nancy improved steadily. She was released nine days later, and we returned to California on a commercial flight.

Getting our primary insurance carrier to reimburse us should have been easy. The diagnosis was obvious on the hospital records even though they were in German; the doctor had written a summary of the diagnosis and treatment in English, and I had sent all the records to the insurer along with the claim. But our primary insurance carrier gave me one lame excuse after another about why they weren’t reimbursing us.

The story changed every time I called them.

First they needed to wait to get an English translation from someone in-house, then they wanted the hospital to translate the records into English, then they wanted me to translate the hospital records into English, then they “Our primary wanted nursing notes in English, then they insurer took about said they needed help converting the bill three months from euros to U.S. dollars and so forth.

That went on for almost three months, and to reimburse us I was getting nowhere. for its share.

A single “please help” call to Robin By comparison, Doles, insurance manager at DAN, led to everything being sorted out. She was DAN’s travel insurance program wonderful. She immediately put me in touch with DAN’s travel insurance carrier,

SHARE YOUR STORY: Has DAN been there for you? Tell us about it at ThereForMe@dan.org.

DAN.ORG

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Rapid ascents, improper gas management, medical problems, poor physical fitness and entrapment are much more frequently associated with dive fatalities and serious injuries than decompression sickness is.

STEPHEN FRINK

Opposite: Of the cases DAN manages every year, 70 percent are unrelated to diving.

The attention divers give to minimizing their risk of decompression sickness should also be given to safety in other aspects of travel and leisure activities.

MORE THAN JUST BUBBLES ARE WE TOO CONCERNED ABOUT DCS? B Y

N I C H O LA S

B I R D,

M. D . ,

MM M

DIVING GRANTS A FREEDOM TO EXPLORE and an opportunity to experience what most people see only on film. As terrestrial creatures, we are ill adapted to the marine world but nonetheless eager to survey the ocean’s wonders. For divers new to the sport as well as seasoned veterans, each dive is unique and requires diligent preparation prior to entering the water. Divers recognize that any excursion into or under the water carries with it some risk of injury.

In numerous articles, seminars and presentations, DAN® proclaims the benefits of physical and mental preparation prior to diving, which include physical fitness, equipment maintenance and skills training. Well represented throughout DAN’s publications and research and integral to the dive industry’s introductory training programs is a focus on decompression sickness (DCS).

The emphasis on DCS indicates the relative importance of this unique malady and the behaviors we can employ to prevent it. Often missing from discussions about DCS, however, is acknowledgement of its relative rarity and the comparative commonality of other injuries that can occur while diving or while on a diving trip.

WHAT HARMS DIVERS? DAN has been gathering dive injury and fatality statistics for more than 30 years. In 2008 a team of researchers led by Dr. Petar Denoble, senior director of DAN Research, published a paper on the causes underlying dive fatalities. While the ultimate endpoint of incapacitating 40 |

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DCS IN PERSPECTIVE Divers spend a great deal of time and money on DCS prevention; all such efforts are laudable and contribute to the low incidence rates that we see in recreational diving (aggregated DCS incidence from all sources is 2 to 4 cases per 10,000 dives).2 In addition, DCS is rarely fatal and, at least among recreational divers, an uncommon cause of long-term disability.

Although severe symptoms, long-term disability and death are rarely associated with DCS, this is by no means an endorsement of unsafe decompression practices or encouragement to slacken preventive efforts. In fact, conservative training standards, adherence to established protocols and diligent monitoring of nitrogen exposure are essential contributors to the relatively low likelihood and consequences of DCS. The point is that divers must not ignore other aspects of their diving activities, no matter how mundane they seem. We must, for example, ensure adequate air supplies and properly configured equipment. On a statistical basis, errors and omissions in these areas have much greater lethal potential than DCS.

E D I T I O N

RUURD DANKLOFF/ISTOCKPHOTO

events is often classified as drowning, the triggering events that lead to these deaths provide insight into how such accidents can be avoided. Whether from healthrelated problems such as heart disease, which accounts for approximately 26 percent of dive fatalities, or other triggering events like running out of gas (41 percent), entrapment (20 percent) or trouble with equipment (15 percent), the majority of dive fatalities stem from human factors.1 This is a recurring theme throughout the published literature on accidents and mishaps in other fields such as medicine and aviation, and it points to the importance of procedures, consistent practices and a disciplined focus on accident avoidance.

Running out of gas, entrapment and equipment problems — three human-related triggers — account for about 75 percent of dive fatalities. The common pathway toward in-water debilitation in most of these cases was asphyxia or rapid ascent associated with pulmonary barotrauma (lungoverexpansion injury) and subsequent arterial gas embolism (AGE). In the unforgiving marine environment, debilitation or unconsciousness usually results in drowning.

It is important to stress the significance of AGE in the fatality statistics and differentiate it from DCS. AGE is far more likely to lead to drowning, as symptoms often occur while the diver is still in the water, the onset is sudden, and they often result in loss of consciousness.

S P E C I A L

SHIFTING THE FOCUS Decompression-related problems represent only a fraction of the injuries and medical problems that traveling divers experience. Dive trips often involve other forms of recreational activities and thus, additional sources of injury.

Of the calls DAN receives from symptomatic individuals who receive evacuation or medical-care-coordination, about 70 percent have injuries that are not related to diving. This is a powerful statistic that points to other causative factors.

Trauma tops the list as the single most common injury type about which DAN receives calls for assistance. From broken legs to car accidents, our evacuation services spend the most time on injuries acquired out of the water.

Whether cycling, driving, walking or riding a scooter, the risk of injury while out of the water warrants enhanced attention. If you’re a diver who wears multiple computers to ensure adequate DCS prevention, don’t put all your safety eggs in that basket and forget to watch your footing on boat ladders. Increase your caution while traveling in areas that have different traffic patterns than those with which you are familiar. A focus on injury prevention is of maximal importance in remote locations; the quality of medical services is not equivalent around the world, and transportation and evacuation to higher levels of medical care may take more time and involve more complications than you anticipate.

Accidents are by definition unplanned. Our best defense against them is education, which enhances our knowledge of possible hazards and guides behaviors that reduce their likelihood. First aid and rescue diver courses are prime examples of programs that don’t just teach people what to do when accidents happen, they promote heightened awareness and a mindset of prevention.

Live safely, dive safely, and may all your dives and travels be accident- and injury-free. AD

REFERENCES 1. Denoble PJ, Caruso JL, Dear GL, Pieper CF, Vann RD. Common causes of open-circuit recreational diving fatalities. UHM 2008, Vol. 35, No. 6. • 2.

Vann RD, Freiberger JJ, Caruso JL, Denoble PJ, Pollock NW, Uguccioni DM, Dovenbarger JA, Nord DA. Annual Diving Report. Divers Alert Network: Durham, NC, 2006; 99pp.

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TIMELINE OF AN EMERGENCY CALL BY

MAT ÍA S

N O C H E TTO ,

M .D .

THE DAN EMERGENCY HOTLINE RECEIVES an average of 5,200 calls per year. DAN medics and physicians work 24 hours a day, 365 days a year to provide emergency medical assistance to divers in need. No matter where they are or what they are doing, these dedicated medical professionals answer the call. The following is a timeline of a recent case that exemplifies how things unfold when a diver calls DAN in an emergency.

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2:28 a.m. ET

Dutch Caribbean — Dive Resort Mr. Smith, who is 56 years old, cannot sleep. His urge to urinate is painful, and upon sitting up in bed he realizes his legs are numb. He is unsure if he can even stand up. Something is wrong. He wonders, “Am I bent? How is this possible? I did everything right.” Mrs. Smith advises her husband to call DAN.

2:35 a.m. ET

(6:35 p.m. New Zealand time) DAN’s Call Center in New Zealand A DAN medic’s phone rings. The medic answers the phone, and after a few initial questions Mr. Smith reports eight dives over the past two days and describes his symptoms. The DAN medic recognizes that this may be serious decompression sickness (DCS), which requires a timely response. The medic recommends that Mr. Smith seek an evaluation at the closest medical facility and call DAN once he is there so a medic can speak to the examining physician. Mr. Smith agrees to ask his dive buddy to help him get to the local clinic.

2:45 a.m. ET

The DAN medic calls the hyperbaric chamber on the island to alert them of a possible case of DCS. This case will likely push the limits of the facility’s capabilities. The hyperbaric doctor on staff agrees this could be a spinal cord hit and alerts the staff.

3:05 a.m. ET

Dutch Caribbean — Medical Clinic Mr. Smith and the evaluating physician call DAN for a consultation. The physician reports that his patient has bilateral lower-extremity weakness, decreased sensation and urinary retention. He agrees with DAN’s initial assessment that Mr. Smith likely has DCS. The DAN medic informs the physician that he has already alerted the local hyperbaric facility, and the physician arranges for an ambulance to transport the patient to the chamber.

3:45 a.m. ET

Dutch Caribbean — Recompression Chamber Facility Mr. Smith requires assistance to get into the chamber because he cannot walk and has a urinary catheter in place. The hyperbaric physician had agreed to treat the diver, but upon examination he realizes the case requires a higher level of care than his chamber can provide. He administers an initial hyperbaric chamber treatment while the DAN medic begins arranging an evacuation to a better-suited facility.

4:05 a.m. ET

(8:05 p.m. New Zealand time) DAN’s Call Center in New Zealand The DAN medic in New Zealand contacts DAN’s medical director in Durham, North Carolina, to brief him on the case; he concurs with the plan. The medic then contacts DAN TravelAssist, which arranges emergency medical evacuations, and briefs them on the case. It is determined that the most appropriate chamber facility for Mr. Smith is in Miami, Florida.

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4:30 a.m. ET

Stevens Point, Wisconsin — DAN TravelAssist Headquarters A DAN TravelAssist representative contacts Mercy Hospital in Miami, which agrees to receive the patient. They alert the treating physician at the chamber that a medical evacuation is being arranged.

5:00 a.m. ET

Dutch Caribbean — Recompression Chamber Facility Mr. Smith reports some improvement during the treatment. He is starting to feel his legs again but is still too weak to resume normal walking. The treating physician explains this is normal and is a good sign. This first treatment will be completed at 9 a.m. ET.

7:00 a.m. ET

(11 p.m. New Zealand time): DAN’s Call Center in New Zealand The work shift on the DAN Call Center in New Zealand has reached its end. The DAN Medic hands over the progress and updates of all ongoing cases to the team of DAN Medics in Durham, North Carolina. A special emphasis is made on Mr. Smith’s case, as critical steps are still taking place.

8:30 a.m. ET

DAN Headquarters in Durham, North Carolina DAN’s Medical Call Center has diverted operations back to Durham North Carolina. The team of medics receives confirmation from DAN TravelAssist that an air ambulance has been contracted to conduct the evacuation, during which the aircraft will maintain sea-level pressure. They will take off from Ft. Lauderdale, Florida, at 9 a.m. ET and should arrive in the Dutch Caribbean at 12 noon ET.

10:00 a.m. ET Dutch Caribbean — Recompression Chamber Facility Mr. Smith has completed his first treatment, and the treating physician reports the patient has recovered some motor function and some sensation. Mr. Smith and his wife will be ready for the medical evacuation by noon.

11:30 a.m. ET Dutch Caribbean — Airport The treating physician, a nurse, a paramedic, Mr. Smith and his wife arrive at the airport, and the air ambulance jet lands soon afterward. After the jet refuels and personnel complete documentation, the patient, his wife, a flight nurse, paramedic, treating physician and the pilots board the plane, which takes off less than an hour after it landed.

3:35 p.m. ET

The air ambulance lands in Miami, where a ground ambulance is waiting on the tarmac.

The travelers promptly clear immigration and customs under special emergency procedures.

4:15 p.m. ET

The ground ambulance travels 9 miles to Mercy Hospital in less than 20 minutes.

4:45 p.m. ET

Miami, Florida — Mercy Hospital Mr. Smith is admitted to the hospital, and a hyperbaric medicine specialist receives him at the emergency department. The doctor and nurses perform examinations, draw blood, confirm the patient’s medical history, complete the necessary paperwork and contact DAN to confirm Mr. Smith’s insurance.

5:30 p.m. ET

The hyperbaric doctor initiates a second chamber treatment, a U.S. Navy Treatment Table 6.

10:30 p.m. ET Following the treatment, Mr. Smith is tired but happy to be regaining strength. The hyperbaric specialist

specialist explains that he is doing well but that these cases are serious and need to be treated aggressively.

Over the next two days Mr. Smith receives four U.S. Navy Treatment Table 5 hyperbaric treatments and has physical therapy between treatments. Medical staff remove the urinary catheter after the fourth Treatment Table 5. Mr. Smith still has residual weakness in both legs but can walk with less assistance.

In the next few days Mr. Smith has four U.S. Navy Treatment Table 9 regimens, and his residual weakness remains unchanged after each of the last three treatments. The treating physician realizes that Mr. Smith has reached a clinical plateau and that further hyperbaric therapy is of no value. Time and continued physical therapy are now the appropriate treatment.

After three months Mr. Smith recovers full strength in his left leg and has only a slight decrement in his right. After two additional months, the strength in his right leg also returns to normal. AD DAN.ORG

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TOUCH AND GO IN TONGA TE X T

During a dive trip to the South Pacific, Douglas Hoffman became so ill he had to be evacuated for surgery to save his life.

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A N D

P H O TO S

B Y

D O U G L A S

H O F F M A N

I STARTED DIVING IN 1985 and have been traveling the world to dive ever since. I have always had DAN dive accident insurance in case I ever experienced a dive emergency, but thankfully I have not needed it. Another reason I’ve always been a DAN member is the evacuation benefit. I had the occasion to use that service just a few months ago, and it saved my life.

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“I don’t plan to have another life-threatening emergency, but I take great comfort in knowing that if a problem arises I am covered.”

For the past 11 years I have guided expeditions dedicated to observing and photographing Southern Hemisphere humpback whales in Tonga, where swimming with the whales is permitted. Known as the friendly isles, this South Pacific nation is about a 90-minute flight from Fiji or a three-hour flight from New Zealand. It’s remote, its infrastructure is lacking, and in many ways going there is like going back in time.

Because of this remoteness, I require everyone who goes on one of my tours to be a DAN member and have DAN dive accident insurance. It is better, of course, to have it and not need it than to need it and not have it. Fortunately, I practice what I preach, because on Aug. 29, 2015, I needed it.

That afternoon we observed a relaxed mother and calf at the surface. After watching them for a while, we decided the time was right and slipped into the water. We swam about 100 feet and saw the whales, so we stopped and watched.

We made no attempt to swim toward them and let them decide if they wanted to interact with us. As it happened, they did, and we floated side by side for more than an hour.

When the encounter began, the mother positioned the baby on her far side. As she became more comfortable with our presence, she made some subtle changes to her position, and the baby reacted by changing its position. The calf swam over the mother’s back and alongside her, close to us.

At one point the mother and I were floating just a few feet apart and looked into each other’s eyes — it was magical.

During that swim I had some stomach discomfort, but I shrugged it off as indigestion. It persisted through the afternoon though and got worse in the evening. The next day was Sunday, and in Tonga nothing happens on Sundays.

I lay in my room and could not find a comfortable position.

The pain was severe. The next day rather than going to the boat I went to the doctor. After an ultrasound and a brief examination the doctor said I had a classic case of ruptured appendix and that I needed an operation or I would die.

Those are not words anybody wants to hear. I went to the hospital, where they put me on an IV and started talking about what to do with me. There was no surgeon in the area, and I would need to be evacuated. So I notified my sister, and she called DAN. That was that. I just lay there, and DAN, along with my local friends Lisa and Amecia and my sister in California, took care of the details. Just prior to sunset an air ambulance landed in Vava’u to take me to New Zealand.

I remember lying on the gurney with an IV in my arm, being in pain and seeing a surreal sunset out the window.

I thought to myself how lucky I was to have a private jet come and get me. Customs officials met the plane on the ground in New Zealand, and by the time the crew got me into the ambulance my paperwork was in order, and I was on the way into lifesaving surgery. I most certainly did not anticipate such a significant health crisis, but by being a DAN member I was prepared for it.

I am a week away from my next whale adventure, this one in Dominica, and you can be sure my DAN membership, dive accident insurance and trip insurance plans are all current. I don’t plan to have another lifethreatening emergency, but I take great comfort in knowing that if a problem arises I am covered. Having insurance not only protects you but also helps your loved ones feel at ease, and that is priceless. I strongly suggest that all divers, especially those who travel to remote locations, get covered.

Thank you, DAN, and safe diving, everyone. AD DAN.ORG

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STEPHEN FRINK

MEMBERSHIP & INSURANCE

DIVERS LOSING ACCESS TO EMERGENCY CARE BY

DI C K

C LA R K E ,

C H T

FOR DIVERS SUFFERING DECOMPRESSION ILLNESS (DCI), the immediate availability of hyperbaric oxygen therapy (HBOT) is imperative. It has frequently proved to be lifesaving. It has resolved paralysis and overcome other forms of damage to the brain and spinal cord. Just as frequently, it has eliminated painful musculoskeletal injuries. Of equal importance to many is that prompt hyperbaric treatment frequently means the difference between being able to return to diving versus being declared medically and perhaps permanently unfit to do so. For certain medical patients, HBOT is likewise sparing of life and central nervous system. It optimizes management of gas gangrene, enhances skin flap survival and reduces the rate of amputations in trauma victims and people with diabetes.

Sadly, for divers injured in the U.S. and patients with the medical conditions listed, there is much to be concerned about. The harsh reality is that the percentage of hyperbaric medicine programs introduced during the last decade that are available on a 24/7 basis to treat divers and these other emergent conditions has collapsed into single digits at best. This contrasts sharply with the prior decade, in which a majority of new programs were available 24/7; this availability was an almost universal standard in previous years. Adding to this conundrum is a growing trend among established facilities to discontinue their existing 24/7 coverage.

This trend has increased in the past 24 months, and the rate at which access is lost continues to accelerate.

Before we examine the history that led to this state of affairs or attempt to identify possible solutions, it may be useful to put the crisis into a human context using several recent case examples. Some are tragic, and all were essentially avoidable.

A CRISIS IN THE MAKING 50 |

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STEPHEN FRINK

Staff dedication is an important factor in keeping hyperbaric facilities available for afterhours emergencies.

Opposite: Built-in breathing systems allow those being treated in chambers to receive air breaks, which mitigate the risk of oxygen toxicity during treatment for DCI.

CASE STUDIES

A retired nurse suffered decompression-induced cerebral arterial gas embolism (AGE) while diving off Florida’s east coast. She was urgently evacuated from the scene to a nearby hospital, one that offered HBOT and had been actively promoting its presence in the community. Consistent with many other recreational diving accidents, this one occurred on a weekend. Emergency-department (ED) personnel unsuccessfully attempted to summon their hyperbaric medicine colleagues. The ED was eventually advised that the hyperbaric service was only available during business hours on weekdays. Furthermore, and by design, they would not offer care to injured divers even if they presented during normal working hours. Following what were described as desperate attempts to locate a hospital that would accept and treat this patient, contact was established with DAN®, which was able to identify an available hospital in south Miami. After being supported for several hours in the ED, the patient was duly transferred. HBOT began soon upon her arrival at the receiving hospital. Unfortunately, she died during her initial hyperbaric treatment.

A middle-aged male patient underwent heart surgery to remove a tumor. During surgery there was inadvertent introduction of a considerable amount of air into his brain’s arterial circulation, causing AGE. This is essentially the same problem that can be experienced by divers who hold their breath during ascent. Immediate, severe neurological collapse occurred. This event also took place on a Saturday in a large city in Georgia that is home to some 12 hyperbaric medicine facilities. None would accept the patient. Eventually, a hospital in an adjacent

state agreed to accept him. Following a determination of the risks and benefits associated with a somewhat lengthy transfer of this recent heart-surgery patient, the transfer was conducted. Unfortunately, and despite an aggressive course of HBOT, the patient failed to improve to any measurable degree. He was committed to long-term supportive care. Treatment delay was a likely contributing factor to this poor outcome.

A recreational scuba diver suffered decompression sickness (DCS) following ascent from a freshwater lake in central Florida. It was a weekday, so the odds of available hyperbaric oxygen therapy would appear more favorable, particularly as a nearby major medical center had been treating injured divers for several decades. Due to budgetary issues, however, this hospital had reduced the number of days per week that the hyperbaric medicine service would be on call. Tuesday was one of the noncall days. This diver, therefore, had experienced a double misfortune. Not only had he suffered DCS, he had done so on a Tuesday.

Unfortunately, the reduced availability of this service had not been widely communicated, particularly to those in a position to refer emergent cases or effect their transfers.

After some delay, the diver was eventually transferred elsewhere in the state and was fortunate to experience complete clinical resolution of his symptoms.

The lone survivor of a coal-mine disaster was rescued after being trapped underground for several days. He was comatose at the time of his rescue and urgently transferred to a nearby medical center in West Virginia. His primary problem was severe carbonmonoxide poisoning. Not having a hyperbaric medicine DAN.ORG

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program, this hospital requested urgent transfer to a nearby hospital that did. Their request was denied on the grounds that the hyperbaric medicine facility was unavailable for emergent cases (it operated as an outpatient wound-care hyperbaric facility). Transfer was arranged some days later to a 24/7 hyperbaric medicine service in a neighboring state. The patient had a protracted hospitalization and incomplete neurological recovery at the time of his discharge.

A HISTORY OF HYPERBARIC CARE IN THE U.S.

To put this serious issue in perspective, one needs to reflect on the evolution of HBOT. Early hyperbaric chambers were not hospital-based. Rather, they could be found at various industrial and commercial worksites.

These chambers served in support of civil-engineering projects such as bridges and tunnels constructed above and beneath various bodies of water. Underground masstransit systems were another common worksite in which a chamber might be present. Caisson workers employed in these projects would enter chambers to decompress from their pressurized work environments. They would return to the chambers to be recompressed (treated) should their decompression schedules prove incompletely protective. By the 1950s a growing number of military diving operations were also supported by onsite recompression chambers.

It was not until the early 1960s that hyperbaric chambers found their way into the hospital setting.

During this period several newly identified therapeutic mechanisms were associated with hyperbaric doses of oxygen. These mechanisms served to extend hyperbaric medicine’s use beyond the treatment of DCI. Patients hospitalized with acute traumatic crush injuries, carbonmonoxide poisoning or gas gangrene were now considered referable to hyperbaric medicine. The ensuing years were characterized by a steady growth in the geographic availability of hospital-based hyperbaric chambers and the number of treatable conditions. At this point, essentially every hyperbaric medicine program was organized and staffed to provide 24/7 care, such was the nature of the majority of its common uses.

A NEW BUSINESS MODEL

By the late 1980s, utilization of the hyperbaric chamber for wound-healing deficiencies was becoming commonplace.

As most of these wounds were chronic, patients were not usually hospitalized. Rather, they traveled to and from the hospital for daily treatments. During the mid-1990s a unique business model was created, one that combined hyperbaric medicine and wound-healing services. This model blossomed to the extent that the great majority of subsequent hyperbaric medicine programs have been organized and operated in this manner.

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The model’s concept was not to provide hyperbaric medicine for the full range of accepted uses. Rather, access normal business hours; extending the availability of hyperbaric medicine to accommodate emergencies would increase equipment expenses. It would also substantially raise personnel costs due to 24/7 on-call coverage and the professional staff necessary to effectively manage these more medically challenging patients. All this extra expense would occur with little commensurate increase in revenue, thereby negatively affecting the profitability of a business model established as a revenue-generating venture. Certainly, the prevalence of this model has improved access to HBOT for those with chronic wounds, but it has done so while creating a significant downside: reduced access to care for divers and other people with emergent medical needs.

Under this business model, hyperbaric chambers are commonly located on a hospital’s campus but often not within the hospital itself. Adjacent medical office buildings represent the usual location. This makes it all but impossible for those patients hospitalized or in the ED (and, one could argue, likely to benefit most from HBOT) to gain necessary access. Outpatient-only hyperbaric programs further distance themselves from the management of emergent and typically sicker patients by not incorporating otherwise standard biomedical monitoring and ancillary support equipment. This includes infusion pumps, electrocardiogram (ECG) and invasive pressure monitors, through-hull tissueoxygen monitoring cables, hyperbaric ventilators and more.

Treatment pressures are frequently standardized at 2 ATA (33 feet) for all patients. This is incorrectly assumed to eliminate any likelihood of seizures due to central nervous system oxygen toxicity and therefore eliminate the need for air-break delivery systems. Air breaks are vital for the treatment of DCI and certain other emergent conditions.

As the regional availability of this normal-businesshours-only model rapidly expanded, hospitals providing 24/7 hyperbaric medicine soon began to feel an economic pinch. Competing outpatient-only programs, by design, sought the more stable, less clinically challenging and typically better-insured patients. Costs required to maintain 24/7 capabilities continue to increase while revenues generated trend down. Thus, a growing number of hospitals have reconsidered their 24/7-coverage position.

Sadly, and all too frequently, the cost argument is winning out over the best-medical-practice argument.

Consequently, a growing number of hospitals have elected to discontinue on-call availability; others have decided to close their hyperbaric-medicine service altogether. The predictable net effect is a significant national decline in the resources necessary to provide and maintain this vital standard of care. Very few new programs are prepared to accept the 24/7 responsibility, and long-established programs continue to opt out. Divers and others for

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which the immediate provision of HBOT can make the difference between a good outcome and a bad one are increasingly being denied necessary and timely access.

A WAY OUT

STEPHEN FRINK

In general, the diagnosis and treatment of a broad range of difficult-to-manage conditions has greatly improved over the past decade, as has patient access to such care.

During this same period, however, the ability to refer patients to hyperbaric facilities with conditions considered appropriate by both the mainstream medical community and by those who underwrite its costs is becoming increasingly difficult.

What solutions exist that might serve to reverse this trend, and how can individuals for whom the early provision of HBOT is vital obtain necessary access? As the principal issue is financial, some possible solutions might include the following:

COURTESY UPENN

1. The rates insurance companies pay to chamber facilities for HBOT are increased for those treatments initiated outside of normal business hours.

2. Insurance company payment rates to chamber facilities for all HBOT are increased for those hospitals that maintain 24/7 emergency availability.

3. Insurance company payment rates are decreased to providers of HBOT that do not offer 24/7 access. This could be worked out to become cost neutral for those paying for care as these savings could be used to pay additional fees to the 24/7-available facilities.

4. A network of hyperbaric medicine facilities is developed to offer 24/7 call response; perhaps some of the necessary funding support can be provided by hyperbaric facilities that choose not to be so available.

5. Insurance companies could expect those facilities that file claims for providing HBOT to be willing and available to provide such therapy for all the conditions the insurance companies consider medically necessary.

DAN maintains an extensive network of chambers willing and able to treat divers. If you have symptoms after diving, we will help you get the care you need. Call the DAN Emergency Hotline at +1–919–684–9111.

STEPHEN FRINK

In the meantime this difficult situation will remain. For those who plan to travel overseas to dive, the news is much better. The business model described is limited to the U.S., where medical services are often provided or managed by third-party for-profit organizations such as venture capitalists, investment houses and commercial banks. Essentially all international hyperbaric chambers remain available to treat divers and other emergent indications for hyperbaric oxygen therapy. AD

In addition to decompression illness, hyperbaric oxygen therapy is used to treat diabetic foot ulcers, delayed effects of radiation, threatened flaps/grafts, acute carbon monoxide poisoning, crush injuries, refractory osteomyelitis, gas gangrene and necrotizing fasciitis.

DAN.ORG

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DCS IN COZUMEL B Y

M A TTH E W

B R E TT

I BEGAN DIVING IN 2013 at age 44. Diving had always intrigued me, and once I got started, I was hooked. There’s nothing else like it. Since that time, diving has inspired my travel, taking me to Palau, Thailand, Socorro, Bonaire and beyond.

For a Midwesterner like myself, however, Cozumel is among the best of dive destinations. It’s close, it’s affordable, and the diving is spectacular.

This past Christmas I visited Cozumel for a week of drift diving. I’ve been to the island several times and always come away with a renewed sense of appreciation for its beauty and awe for the eagle rays, sea turtles and other marine life that call the waters home.

Our first morning dive was a checkout dive to determine everyone’s skill level before the week of diving. It was easy, with a maximum depth of 75 feet for 50 minutes. The current was slight, and the visibility was spectacular — an ideal first dive. It closed with a nice, slow ascent and a three-minute safety stop.

BRANDON COLE

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COURTESY COSTAMED

When we returned to the boat, I removed my wetsuit and stashed my gear. I felt a sudden tingling in my right foot followed by a dull ache in my knee, as if I had just finished a long run. I assumed the worst, thinking I had decompression sickness (DCS). When I reviewed the dive in my mind, however, that seemed impossible. I’ve had similar or more challenging dive profiles hundreds of times. Furthermore, I was diving 32 percent nitrox. Since most of the divers in our group were on air, we all dived an air profile, and I use a conservative dive computer.

Given all these factors, I dismissed my initial concerns; after an hour surface interval, I made the second dive without further thought. The following day I did two morning dives with similar depth profiles. The tingling in my foot was gone, but my knee continued to be bothersome. It simply felt off, but not in a way that was typical of muscle or joint soreness. At this point I was beginning to appreciate the old saying that the first symptom of DCS is denial.

When I returned to my hotel, I called DAN with what I assumed was an overabundance of caution. I spoke with a medic, who patiently noted my dive profiles and symptoms and then calmly but firmly said, “You need to get to a hospital.”

Those are not words anyone wants to hear, especially when on vacation.

By the time I arrived at Costamed, the recommended health care provider in Cozumel, DAN had already contacted them, and Dr. Jorge Darío Gómez Castillo was waiting for me. My first question to him was, “Are you a diver?” He smiled, nodded and performed some balance and reflex tests. He told me to close my eyes and hold my hands in front of me with palms up. I was sure I could do that, but I almost fell over, and he had to catch me. I finally realized how bad my condition was.

Sure enough, I had a mild case of DCS. They immediately put me on IV fluids and 100 percent oxygen and recommended a U.S. Navy Treatment Table 6 recompression therapy in the hyperbaric chamber. It was all painless, just a bit boring and uncomfortable. I passed the time watching John Wick movies with the chamber tender, although my view of the screen was only through the chamber’s porthole.

My knee pain lessened throughout the treatment.

I stayed at Costamed overnight and had a posttreatment evaluation the next morning. My knee pain was gone entirely. They discharged me with a recommendation to not dive until I had a follow-up review with a physician and received clearance to return to diving. I spent the rest of the week above the water, disappointed about not being able to dive but grateful I was OK. My case of DCS was mild, but it could have easily been much worse. When I recall my dive and actions leading up to it, I draw a blank regarding what triggered the

S P E C I A L

From left: Staff members monitor and communicate with patients at the Costamed chamber. • The author prepares for his chamber treatment.

Opposite: A diver swims over a coral reef bright with rainbow colors of rich sponge growth in Cozumel, Mexico.

incident. There was no violation on my dive profile and no exacerbating circumstances regarding dive conditions.

The only possible contributing factor I could come up with was potentially being dehydrated. I traveled from Chicago to Cozumel the day before diving and likely did not drink as much water as I typically would.

The reality is that not identifying a cause should not change your response to experiencing symptoms. There’s a tendency to not talk about getting DCS — the prevailing wisdom being that the diver must have been at fault and made a mistake. Diver error is not always the case, and this shaming is counterproductive to divers seeking treatment when they think they may have DCS. Dr. Castillo said that 80 percent of the patients he treats for DCS were diving within safe profiles.

I should not have waited until the second day to get treatment simply because I thought it was impossible for me to have DCS. I have two pieces of advice for my fellow divers. First, if you think you have DCS, there’s a good chance you are correct. Just because you followed every rule and dived conservatively doesn’t mean it can’t happen to you. Follow your gut instinct and call DAN. Don’t try to rationalize your way out of making the smart choice for your health. A minor case of DCS left untreated can become highly problematic.

Second, make sure your DAN membership and dive accident insurance are current. I can’t say enough about how quickly and thoroughly DAN handled my case, helping me navigate health care in a country where the logistics would have been daunting. Not having to be concerned about paying out of pocket for medical care was a huge load off my mind. I had enough things to deal with without adding that into the mix.

My 2021 goal is to get my divemaster certification, and when I do, it will be in Cozumel. You can be sure that my DAN membership and dive accident insurance coverage will be current.

Many thanks to DAN, Dr. Castillo and Costamed of Cozumel. Safe diving to all. AD DAN.ORG

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MEMBERSHIP & INSURANCE

REDUCE YOUR LIABILITY RISK

BY FRANCOIS BURMAN, PR.ENG., M.SC.

DIVING IS INHERENTLY RISKY, and dive professionals must take care of their customers and do their best to prevent accidents. But accidents may occur despite the best efforts to prevent them.

Training, awareness, emergency action plans and insurance can help mitigate the consequences of accidents, but nothing can truly prevent you from being sued or even criminally charged. While insurance can limit your financial losses, accidents may produce consequences that can harm your reputation, cause you to face significant downtime with an associated loss of income, and may even have moral consequences that can cause personal health issues.

Prevention is key to reducing your risks; understanding these risks will help limit your exposure to legal consequences.

The following are a few of the most important risk factors to consider. While not an exhaustive list, these items are from incidents of damage, injuries and fatalities that prompted lawsuits.1 • Failing to have, practice and implement an appropriate emergency action plan (EAP) — Taking inappropriate action in response to an accident or failing to follow the EAP can render worthless even the best preparations.

• Losing a diver — Hundreds of resources can help you reduce this risk, but managing this situation when it occurs requires a specialized EAP. • Failing to properly assess dive site conditions — Improper assessment, which includes accounting for situational changes and the required experience and preparedness of divers, can lead to liability exposure and injuries or fatalities.

• Failing to use a suitable health questionnaire and enforce its recommendations — Dive professionals need to create and follow formal procedures carefully to avoid causing harm to a student while still ensuring their privacy.

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• Having inadequate preexcursion, predive and postdive briefings — Briefings must be thorough and given consistently before and after every dive or dive trip, regardless of the group’s experience levels.

• Lacking appropriate first aid equipment and supplies — Plan for the longest return-to-shore journey in the event of a dive injury that requires oxygen, and consider the possibility of multiple victims. Ensure your supplies and equipment are sufficient, appropriately maintained and not expired. Being unable to render first aid presents significant risks.

• Failing to comply with adequate instructor-tostudent ratios — These ratios exist to keep students safe, so not only is noncompliance a standards violation, but it can also result in undue harm, a diver lost at sea or even a fatality.

• Lacking suitable communication equipment — Divers need to be able to reach assistance in times of need. Most maritime rules require specific redundancy; sole reliance on a cell phone during shore or inland diving is ill-advised.

• Neglecting self, student or buddy checks — Failing to regularly and adequately perform these checks exposes every diver to accidents, especially when overlooking gas and buoyancy deficiencies.

The exposure risk to liability and other claims for damages varies per location and depends on environmental conditions, the market, inherent site risks and geographic location, among other considerations.

A careful risk assessment of each operation at every site is necessary to identify these exposures. Appropriate risk mitigation, enhanced awareness, staff training and retraining, and adequate professional liability insurance are essential to prevent accidents, control as much damage as possible in the event of an accident and provide you with suitable legal defense protection.

When an accident occurs or if you suspect something may happen, it is essential to immediately report these situations to your training agency and your insurer, no matter how great or small the anticipated consequences may be.2 Failure to report can seriously inhibit the ability of your insurance carrier to respond appropriately and protect your interest. Being prepared and having the incident on record will enhance your protection from potential consequences. AD

NOTES: 1. The DAN Risk Assessment Guide for Dive Operators and Dive Professionals, which identifies many additional legal liability risks, can be found online as a free download at DAN.org/research-reports/publication-library/. • 2. Download DAN’s article on incident aftermath at DAN.org/wp-content/uploads/2020/08/incident-aftermath-what-to-do-liability.pdf.

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E D I T I O N

SAFETY SERVICES 58 Survive Your Dive 60 Choosing Safety 62 Preventing Breathing-Gas Contamination 64 Invisible Crystals 66 Experience and Risk 68 You’ll Be OK 70 Freediving Safety 74 What Drowning Really Looks Like 76 Dive Boat Fire Safety 78 The Social Psychology of Safe Diving 80 When Things Go Wrong

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SAFETY SERVICES

SURVIVE YOUR DIVE A U.S. COAST GUARD PERSPECTIVE B Y P E TTY O F F I C E R H E N R Y D U N P H Y A N D LI E U TE N A N T J O H N D O W N IN G

Guard, but we also see the tragic results when people underestimate the hazards.

The adventure and thrill of diving are appealing to many, but the ocean is an unforgiving environment — and even less forgiving to those who recreate beneath the surface.”

— Rear Adm. Karl Schultz, commander of the 11th Coast Guard District 58 |

2021 SPECIAL EDITION

1. Is your training adequate for the current and predicted conditions? Will you respect the limitations created by the conditions and stop diving when conditions change or exceed your personal limits?

All the normal hazards of water sports are magnified for those who spend time beneath the surface. Strong currents can occur at any time of year. Cold water temperatures, limited air supply, reliance on equipment for survival and the lack of underwater rescue capabilities make it essential that divers are fully aware of their limits and prepared for all possible problems.

2. Are you prepared to abandon your weights, inflate your buoyancy compensator and signal for help when in distress?

Divers should not be afraid to ditch their weights, end their dives and signal for help at the first signs of distress. Interviews with divers who have experienced distress reveal that many of them did not understand they were in danger because they had

PHOTOS BY CORY J. MENDENHALL / COURTESY U.S. COAST GUARD

RECREATIONAL DIVING IS BY AND LARGE A SAFE ACTIVITY, but when accidents occur the outcomes are often frightening and can be fatal. The beautiful blue world below can quickly become hostile for divers who lack adequate training, are in poor physical condition, use improperly maintained equipment or are otherwise unprepared.

Although the U.S. Coast Guard does not have regulatory authority over recreational diving as it does for recreational and commercial boating, Coast Guard search-and-rescue crews are frequently called on to assist when divers are lost or in trouble. In the aftermath of a dive injury or death, the Coast Guard marine casualty investigators work with other public health and safety organizations to identify what went wrong and evaluate how to prevent future accidents.

In 2009 the Coast Guard began to forge strong partnerships with the San Diego Lifeguard Services, the San Diego Harbor Police, the San Diego County Medical Examiner’s Office, the University of California San Diego Health System and the Scripps Institution of Oceanography to analyze dive incidents. The committee formed by “Nobody understands these groups produced six recommendations based on a comprehensive review of the allure of the sea diver fatalities in the San Diego area. The committee encourages divers everywhere to ask themselves the following questions: more than the U.S. Coast

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not been taught how it would feel; therefore, divers should signal for help if they have any concerns at all.

3. Is your physical fitness adequate for the current and predicted conditions? Have you checked with your primary doctor to ensure that you are in good enough health for intense physical exertion?

Diving is a strenuous physical activity involving physiological demands unlike those of any other sport.

Many dive fatalities are caused by heart attacks, and the risk is especially great for divers over the age of 45. Divers who have not dived in more than a year should consult with their primary-care physicians before attempting to return to the sport. They should then reassess their abilities with a simple or less-challenging dive.

4. Are you diving with a buddy? Have you reviewed each other’s abilities, equipment and plans?

In addition to planning, health, physical fitness and awareness of weather and sea conditions, dive-safety experts stress the importance of the buddy system. Divers should never dive alone. They should always have detailed plans (which include times and locations) that they share with someone ashore.

5. Do you feel completely comfortable making this dive?

It is essential to prioritize safety and remain realistic about upcoming dives. Any hesitations about any aspect of a

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E D I T I O N

dive should be completely resolved prior to commencing the dive. Divers should also clearly understand their experience levels and only attempt to exceed these limits when the conditions are optimal and they are diving with more experienced partners.

6. Do you plan to enter overhead environments? If so, do you have the proper training and equipment, and are you familiar with the necessary procedures?

Diving in caves, wrecks or any overhead environments in which the path to the surface is indirect necessitates additional training, equipment and air supply. In overhead environments, prepare yourself for confined spaces, entanglement and disorientation.

According to the Coast Guard’s Tactical and Strategic Statistics, in the past four years (2010-2013)the Coast Guard was called for assistance in 63 fatal dive accidents and 55 diving-related injuries. We hope that publishing these safety tips will lead to fewer dive-related tragedies.

“The Coast Guard doesn’t regulate recreational diving but is generally called in to assist during diving emergencies,” Schultz said. “In many of these dive emergencies, injuries and death are preventable. We want everyone who enjoys the water, including divers (whose sport leaves little room for error), to make safety their top priority. We want you to survive your dive.” AD

A crew member operates the hoist on an MH-65C Dolphin helicopter during training operations off the coast of Los Angeles.

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SAFETY SERVICES

JILL HEINERTH

CHOOSING SAFETY B Y

The social context is an essential reality of recreational diving. Setting and following good examples is a responsibility of all divers.

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2021 SPECIAL EDITION

K A R L

S H R E E V E S

IN MANY WAYS WE DO HAVE A CULTURE OF DIVE SAFETY: Even though we sometimes see departures from recommended practices, the incident rate would be far higher were the cultural norms in diving less focused on safety. Still, we are always striving to improve, and to that end I think it’s worth looking at how “affective” education can help promote our cultural safety values.

Affective education is concerned with values, attitudes and how we teach people to make good choices. Teaching knowledge and skills can be fairly straightforward, but it is much more difficult to influence how people apply their skills and knowledge. For example, school systems teach children about the risks of smoking, and almost all students demonstrate that they understand these risks when tested. Nonetheless, every year, as illogical as it is, a substantial number of youths take up smoking. Why? Role-model behavior is one of the most important influences on people’s decisions. Within any culture, people tend to follow the example of respected leaders, so it makes sense that

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E D I T I O N

After the dive, several others in the group confided that they were glad I had spoken up. I was probably the best prepared diver on that boat, but none of the others had said anything. Why was I the one to protest? Obviously, something about the situation made them feel as though they shouldn’t object. We must all actively participate in creating a culture in which people feel confident not only in their dives but also in their decisions to change a dive plan. Every one of us can proactively enhance the culture of dive safety in this way.

If we want a model for our culture of dive safety, we can look to the early cave-diving community. Once cavediver training and certification became established, that community took a hard line on its cultural safety values.

Cave diving by noncertified individuals was simply not tolerated within the ranks. No one in the community would cave dive with someone who lacked the proper gear or training, and the social pressure was biased toward safety.

The “anyone can cancel any dive at any time for any reason” philosophy was born in this era and remains today, reinforced by an attitude that you have failed if you even think you may have a problem and don’t call the dive.

Your buddies might even mildly berate you for not being willing to cancel a dive if you feel uncomfortable about it.

After the inception of formalized cave-diver training and the establishment of that community, more than 20 years elapsed before a certified cave diver died in a cave, which is remarkable for such an advanced diving technique. Even today, fatalities among certified cave divers are infrequent.

(There have been hundreds of diver deaths in caves, but more than 90 percent of the fatalities were not certified cave divers.)

The bottom line is that if we want to maintain and improve our culture of dive safety, all we have to do is choose to dive safely. We must do what we’ve been trained to do: set and follow good examples, speak up when things don’t seem right, and refuse to dive with anyone who does not do the same. It really is that simple. AD STEPHEN FRINK

respected dive leaders who exemplify conservative diving behavior should lead a culture of dive safety. A major role of training organizations should be to identify and either retrain or expel instructors who do not follow training standards. PADI engages in these practices by administering random post-training surveys. Most of the training organizations communicate with each other, which makes it difficult for a particularly recalcitrant instructor to continue teaching by simply affiliating with a different certifying agency.

Social pressure exerts influence on our choices, for better or worse, and proper dive training assists positive social pressure and resists negative pressure. For example, beginning divers learn depth limits appropriate to their experience and training in their courses. All else being equal, beginners are more likely to heed recommendations to follow the limits than to heed recommendations to ignore them. Still, as the smoking example shows us, “all else being equal” is a huge qualifier, and there’s a limit to what training alone can do. Although it would be best for people to avoid being influenced by social pressure to make poor choices, a culture of dive safety can thrive only if we use social pressure to model and enforce values that promote diver health and well-being.

Saying we should be role models is another way of saying we shouldn’t be hypocrites. If you agree that established limits are important for safety, then follow those limits. If you agree that divers should be certified before engaging in certain activities, don’t engage in those activities unless you are certified. If you agree that certain equipment should be mandatory for certain types of diving, don’t do that type of diving without the mandatory gear — no matter who you are.

Everyone in a culture either enforces the cultural values or else works against them. We enforce values by exerting social pressure on those who don’t comply, or we undermine the values by exerting social pressure on those who do. To enforce safety values, we should refuse to dive with people who don’t honor those values, and we should speak out against any unsafe recommendations. We should also welcome and invite safety-related questions at any time. Making people feel as though they can’t raise questions or challenge dive plans undermines the safety values we would like to promote.

I was once on a dive boat in a group of six divers when a respected dive leader asked us to check out a site at 130 feet. It was a repetitive dive with moderate current, and I considered it within my capabilities. However, when I learned that the boat did not have enough line to anchor and that we would “freeboat-drift” the dive, I felt uncomfortable and let the dive leader know. To his credit, he said, “OK, let’s plan something different.” We renegotiated the plan and made the dive without a hitch.

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STEPHEN FRINK

SAFETY SERVICES

CO is tasteless and odorless; detection requires testing.

PREVENTING BREATHINGGAS CONTAMINATION B Y

CONTAMINANT

Carbon monoxide (CO)

Carbon dioxide (CO2)

B R I TTA N Y

TR O U T

INCIDENTS INVOLVING BAD BREATHING GAS — be it air, nitrox, trimix or another mixture — are rare, yet they do occur. Health effects on divers vary depending on the contaminant breathed. Among the most severe symptoms of breathing contaminated gas are impaired judgment and loss of consciousness, both of which may be deadly underwater.

Sources of contamination include hydrocarbons from compressor lubricants, carbon monoxide (CO) from engine exhaust (or overheated compressor oil) and impurities from the surrounding environment such as methane and carbon dioxide (CO2). Dust particles in breathing gas can also be hazardous, potentially impairing respiratory function or damaging diving SIGNS AND SYMPTOMS equipment. Excessive moisture can cause Headache, dizziness, corrosion in scuba cylinders and other weakness, nausea, dive gear and may cause regulators to vomiting, shortness of breath, impaired judgment, freeze due to adiabatic cooling (heat loss confusion, unconsciousness, potential death subsequent to increased gas volume).

Hyperventilation, dizziness, confusion, unconsciousness

Volatile hydrocarbons

Fatigue, headache, confusion, impaired judgment, numbness, cardiac arrhythmias, unconsciousness

Oil (condensed)

Headache, nausea, impaired respiratory function

Dust (particles) Methane

Opposite, from left: A neat and clean filling room promotes adherence to quality control. • Test kits and paperwork for sampling and sending off breathing gas

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2021 SPECIAL EDITION

RECOMMENDATIONS FOR COMPRESSOR OPERATORS

Compressor operators can help prevent gas contamination and mitigate the risk Impaired respiratory function of dive accidents in several ways.

Attentive compressor maintenance.

Asphyxia due to dilution hypoxia Proper compressor maintenance helps ensure breathing-gas quality as well as extends the life of the compressor. Breathing-gas contamination is less likely in well-maintained and properly functioning compressors. If maintenance is neglected and the compressor overheats, the lubricating oil may break down and produce CO and other noxious byproducts.

Effective procedures. A fill checklist can help ensure safety procedures are remembered when cylinders are filled. Before starting to fill tanks, the operator should inspect the compressor’s filters for damage and note the presence of contaminants such as cigarette smoke, paint fumes or engine exhaust near the intake. If the operator notes any chemical or oily odors after filling has started, he should shut down the compressor immediately. Other useful strategies for

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CONTAMINANT

MAXIMUM LEVELS

Oxygen

20-22%

Carbon dioxide

1000 ppmv

Carbon monoxide

10 ppmv

Total hydrocarbons, including methane

25 ppmv

Oil/particles

5mg/m

Water vapor

67 ppmv

Objectionable odors

No odor

3

Sources from the Compressed Gas Association (CGA): CGA G-7.12011: Commodity Specification for Air (Grade E: SCUBA air) and CGA P-5-2013: Suggestions for the care of high-pressure air cylinders for underwater breathing (water vapor content converted to ppmv).

STEPHEN FRINK

DOWN UNDER SURF AND SCUBA

AIR QUALITY SPECIFICATIONS FOR RECREATIONAL DIVING

E D I T I O N

B R I T TA N Y T R O U T

reducing the risk of gas contamination include keeping records of air fills and maintenance, ensuring operator qualifications are up to date, using proper oil and filters, and maintaining a clean and organized tank-filling room.

Air-quality testing. As a diver descends and ambient pressure increases, the amount of gaseous contaminants breathed also increases. This explains why a contaminated gas that is not toxic at the surface may be at depth.

Breathing gas must be tested for a variety of contaminants both regularly and continuously to ensure compliance with diving-adjusted contaminant levels.

Compliance with breathing-gas quality standards is not strictly enforced, and most of the responsibility for testing lies with the operator. Several methods of testing are available to compressor operators, and they vary in price and complexity. Continuous CO-monitoring devices include electrochemical sensors with color indicators.

Devices that continuously monitor moisture level are also available. Operators can send a breathing-gas sample to an accredited laboratory for analysis of oxygen, CO, CO2, moisture, oil/hydrocarbons and even particulate matter; this is recommended on a quarterly basis.

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proximity of the compressor intake to sources of exhaust, and look to see whether the compressor has an hour meter that can be monitored for regular maintenance.

Always conduct a predive gas check. If your breathing gas has an unusual odor or taste, do not dive with it — this is a red flag for oil or combustion contamination. However, keep in mind that not all contaminants can be detected this way; CO, for example, is odorless and tasteless. Electronic CO detectors or products such as CO-PROTM can be used to detect the presence of CO in breathing gas. Divers should always use oxygen analyzers to determine the level of oxygen in a nitrox mixture to prevent oxygen toxicity.

CONFIRMING CONTAMINATION

Identifying contamination incidents based on symptoms alone is difficult, as the associated symptoms are often similar to other diving-related and nondiving illnesses. If a diver suspects he was exposed to bad breathing gas, he should seek a medical evaluation and have the gas tested.

Observing the health of other divers who had their tanks filled at the same source may be helpful in determining whether a diver’s symptoms are related to contamination.

DAN RESEARCH

RECOMMENDATIONS FOR DIVERS

Ask questions and be observant. If you are unsure about the breathing-gas quality at a fill station, ask questions about compressor maintenance, procedures and testing. Ask if the compressor operator monitors for CO and how often they send samples to a lab for analysis. Look for posted breathing-gas-analysis reports, and note whether the fill room is clean, organized and well ventilated. Observe the

DAN occasionally receives reports of problems from divers breathing contaminated gas, but we suspect this issue is underreported. To encourage divers to report compressedgas contamination, DAN will assist with gas analysis.

If you were involved in an incident possibly related to breathing contaminated gas and you have lawful control of the tank, please preserve the tank and contact DAN Research at +1–919–684–2948 or at DAN.org/safetyprevention/incident-reporting/. AD

REFERENCES Burman F. Scuba air quality. Alert Diver Southern Africa. Autumn 2013: 14-18; Millar IL, Moudley PG. Compressed breathing air: the potential for evil from within. Diving and Hyperbaric Medicine. 2008; 38: 145-51.

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SAFETY SERVICES Polymorphic crystallization inside hoses has recently emerged as a hazard divers should be aware of.

STEPHEN FRINK

INVISIBLE CRYSTALS C RY S TA L L I Z E D N Y L O N - H O S E I N T E R I O R S C A N C A U S E R E G U L AT O R FA I L U R E S B Y

We ask all divers who observe this inner-hose degradation to please email DAN at riskmitigation@ dan.org, preferably providing pictures that show the condition of the hose. This will enable us to capture as much information as possible so we can learn more about this phenomenon.

We will share any new findings, cautions and advice with the dive community.

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2021 SPECIAL EDITION

F R A N C O I S

B U R M AN ,

P R .

EN G . ,

M . S C .

SCUBA EQUIPMENT FAILURE OR MALFUNCTION is a relatively rare factor in diving-related accidents and fatalities. When it does occur, the most common and hazardous malfunctions involve regulators and buoyancy compensator (BC) power inflators.1 Thus, a recent report to DAN of a regulator failure was not necessarily surprising, but the cause in this particular case turned out to be quite unusual.

Although the diver involved in the incident managed the situation very well, and no one was harmed, an inexperienced or nervous diver might not have been so fortunate. It was particularly strange that although the diver’s cylinder was not empty, the gas flow had slowed and then ceased in a way that resembled an out-of-air situation. Closer examination of the equipment led to a puzzling discovery: A large amount of yellow crystallized material was blocking the inside of the braided second-stage regulator hose. The hose had been in use for a few years but showed no external abnormalities or signs of deterioration.

While trying to solve the mystery, we discovered this was not an isolated case. The same situation occurred July 22, 2015, and was reported subsequently in a technical diving blog.2 Further reports from a hose manufacturer and at least one equipment-servicing workshop in a popular diving region revealed that these were not isolated events. Although no injuries have been reported, the discovery prompted a wider, global investigation, which is ongoing.

Analysis revealed the culprit to be a form of polymorphic crystallization — a phenomenon associated with cyclical heating and cooling at oil-water interfaces.3 In both incidents, the crystallization seemed to be related to the molecular structure of the internal tube. The current theory is that repeated cyclical heating and cooling of the hose lining promotes this form of crystallization in materials either unsuitable for this application or affected by certain chemicals or bacteria. The sun heats the hose, then the flow of breathing gas cools down the internal surface of the hose again. This process recurs with each dive, and the crystals grow and accumulate over time. Enough crystals eventually form to encroach on the gas flow, or they migrate toward the second-stage regulator, resulting in significant failure of the breathing device.

So far the reported incidents have been in tropical climates with gear that is several years old. We have not received reports of this problem with vinyl hoses, and given the number of braided hoses out there (both as original components and replacement parts) the incidence is likely quite small.

But because this hazard threatens divers’ air supplies, it is of great potential interest to the dive community. The challenge is determining how best to respond to this discovery. It’s important to identify what divers need to know right now as well as what precautionary maintenance guidelines and early detection strategies they should implement at this stage.

SHERYL SHEA

The standard safety recommendation regarding regulator hoses has been that they should be inspected regularly for signs of external deterioration. Disintegration or abrasion of the outer rubber coating eventually predisposes hoses to rupture during pressurization or even when in use.

Rubber hoses are quite prone to this condition, which is why polymer-braided hoses were developed. But herein lies the problem: The outside of braided hoses can appear normal, flexible and free from obvious abnormalities, while a deteriorated internal surface would be completely invisible to a cursory external inspection.

It would be premature to speculate that this deterioration is limited to braided hoses. Previously, hoses comprised a rubber inner hose, a single braid layer for reinforcement and finally a rubber outer sealing layer. Today the rubber inner hose is sometimes replaced with a polyurethane or nylon hose (referred to as thermoplastic). The middle or reinforcing layer is a polymer-filament braid, and the outer layer is either a second braid — which has the advantage of indicating when the inner hose has a leak — or a polyurethane or synthetic-rubber sealing layer.

Newer second-stage hoses with a thermoplastic inner layer may be vulnerable to degradation. This risk does not apply to internal layers of synthetic rubber, which appear to be impervious to this phenomenon. DAN Research would normally wish to conduct more in-depth analysis with a wider sample of defective hoses, but because this is a potential hazard to regulator function we prefer to err on the side of caution and report this phenomenon now.

WHAT DOES DAN RECOMMEND?

DAN has contacted manufacturers of outer braided hoses to assess possible causes and precautionary measures, and we feel it is important to advise divers as follows: • All regulator hoses, including braided hoses, have a limited service life regardless of external appearance

S P E C I A L

STEPHEN FRINK

SHERYL SHEA

J AV I E R P O L A N C O

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E D I T I O N

Clockwise from far left: Degradation is a slow process, invisible until there is a total failure (top). • This hose interior is not affected by polymorphic crystallization.

• Replace old hoses, limit hoses’ exposure to high temperatures, and follow manufacturers’ maintenance recommendations. • This open hose shows the extent of degradation.

or reinforcement and protection provided by hose protectors or the braiding itself. The failed hoses we have seen are more than five years old.

• The internal section of newer hoses with a thermoplastic inner layer appears to be uniquely prone to polymorphic crystallization, especially in hot, tropical locations.

The phenomenon appears to be a gradual process, but the disruption of gas flow and regulator function is unpredictable and invisible to external inspection.

• If there is any indication of gas-flow restriction, particularly when using a newer hose, the diver should immediately stop using the regulator. Perform a careful inspection of the regulator and the hose. If the regulator is not the cause, suspect the hose.

• Physically examine hoses by squeezing them every inch or so to assess whether they exhibit the same degree of flexibility. Any change in resistance while squeezing along the length of the hose would be a sign of a possible problem. This test is much easier to perform with braided hoses than with harder, outer rubberized hoses.

Following this advice, especially the recommendation to regularly inspect hoses, will give you greater confidence that your hoses will perform as they should. Advocate for dive safety by promoting the following ABC strategy: • Air awareness: Make all divers aware of this problem and the need for regular equipment servicing.

• Buddy breathing: Practice emergency air-sharing procedures to ensure preparedness for and appropriate action in the event of regulator failures or out-of-gas situations.

• Customer choice: Ensure that any hose purchased displays on the ends information about the manufacturer, the production date and the standard used. Check that this information is consistent with that on the packaging. AD

REFERENCES 1. Vann R, Lang M. Recreational diving fatalities. Undersea Hyperb Med 2011; 38(4): 257-60. • 2. Davis A. Nylon-braided regulator hose diving emergency.

Scuba Tech Philippines. July 22, 2015. scubatechphilippines.com/scuba_blog/regulator-hose-diving-emergency/#Polymorphic_Crystallization. Accessed October 4, 2021. • 3. Douaire M, di Bari V, Norton JE, Sullo A, Lillford P, Norton IT. Fat crystallisation at oil-water interfaces. Adv Colloid Interface Sci 2014; 203: 1-10.

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SAFETY SERVICES

EXPERIENCE AND RISK B Y

K A R L

S H R E E V E S

ALTHOUGH IT IS CLEAR THAT DIVING EXPERIENCE reduces divers’ risk of injury, experience is an imprecise term that conjures different ideas in different people at different times.

In contemplating how experience reduces risk, we need to consider the following: • Training provides experience.

• Practice provides experience.

• Diving provides experience.

• Not all experience is helpful.

• If some factors are present, experience can increase risk.

TRAINING PROVIDES EXPERIENCE.

As much as we like to say, “There’s no substitute for experience,” there actually is a substitute: training.

And this is a good thing — you wouldn’t want to learn through experience that you shouldn’t hold your breath while scuba diving. Training lets us benefit from the (sometimes painful or deadly) experience of others, which is why it’s the first step in becoming and growing as a diver. But we must be willing to learn from others’ experience. As Douglas Adams (author of The Hitchhiker’s Guide to the Galaxy) observed, “Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.”

PRACTICE PROVIDES EXPERIENCE.

During training and (one hopes) outside of training, divers practice skills including emergency procedures. This practice gives us experience in controlled circumstances in which we can mess up, learn from our mistakes and try again until we succeed — without actually getting hurt.

Fortunately the brain does not really differentiate between simulated circumstances and reality.

When faced with the real thing, people do as they trained and practiced, and the more realistic and varied the practice, the better the responses.

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STEPHEN FRINK

Regularly practicing emergency skills such as sharing air is a great way to gain the kind of experience that can prove helpful when problems occur.

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This outcome assumes that you actually train and practice.

Explorer, instructor and rebreather designer Kevin Gurr once said, “Practice a skill on every dive.” By that he meant an emergency skill. Following his advice is easy and takes little time. Divers can also gain experience by simulating (within the scope of their training) and managing realistic emergencies in confined water. Another instructor and explorer, Phil Short, said, “I do it when I don’t have to, so I can when I do.”

DIVING PROVIDES EXPERIENCE.

Diving provides experience that’s hard to get though instruction (this is what we really mean when we say there’s no substitute for experience). By going diving we subconsciously learn normal patterns — how things are supposed to be and what we are supposed to do in different circumstances and underwater environments. When something violates our subconscious expectations, we go on alert, sometimes reacting intuitively even before a problem occurs.

There are numerous examples of this intuition in different endeavors. One example documented by cognitive psychologist Gary Klein, who is one of the primary researchers in this area, involved an experienced firefighter who led a crew into a house to fight what seemed to be a routine kitchen fire. They sprayed the fire, but it almost immediately roared back to life. Uneasy, the commander ordered his crew out. Moments later the floor collapsed as a huge undetected fire in the basement engulfed the structure; everyone would have died if they had stayed in the house.

Right after a close call, those involved often say they didn’t know how they knew something was wrong, they just did. Deeper analysis commonly finds multiple subtle pattern deviations that even trained people may not have noticed consciously, but their subconscious apparently did.

The lead firefighter said he saw no threat, but he somehow knew something was terribly wrong. Later examination found that besides the fire roaring back to life, the room was much hotter than it should have been, and the men reported it was unusually quiet (the hidden fire was muffled in the basement). Unconsciously, these pattern mismatches warned the commander.

Experience will keep us out of trouble — if we allow it to. In other words, if something doesn’t feel right when diving, don’t wait to find out why. Trust your intuition, and act accordingly.

NOT ALL EXPERIENCE IS HELPFUL.

It’s not just the quantity but also the quality of experience that counts. We need enough repetitive experience to learn patterns, but beyond a certain point, more doesn’t benefit us.

Consider two divers, one with 1,000 dives and one with 200 dives. The first is an open-water diver who has made all 1,000 dives on about a dozen shallow tropical coral reefs,

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all from a boat in a wetsuit and wearing an aluminum 80 cubic foot cylinder. The second diver has about 50 dives on similar reefs, plus 40 dives in kelp, 20 dives in a cold-water reservoir, 15 dives in a river, 20 dives on Atlantic wrecks, 25 in Florida’s springs and the rest in inland quarries and off Florida’s gulf coast. The second diver is certified as an advanced open-water diver, cavern diver, rebreather diver and drysuit diver and has dived from boats and shore, including through surf. Which diver has the most useful experience that will help reduce risk, especially when visiting a new environment for the first time?

There’s nothing wrong with making a dive you like for the umpteen-billionth time, but be realistic about how much it is or is not contributing to your experience.

EXPERIENCE CAN INCREASE RISK.

Be cautious of normalization of deviance, which can be summed up as getting used to not following your training because nothing bad happens. If someone violates safe diving practices (e.g., exceeds training limits, omits standard gear, skips checklists, etc.) and nothing goes wrong, there’s greater likelihood the person will violate these practices again. Experience makes this worse, because repetition without negative consequences makes the safe practices that were omitted seem unnecessary, until the deviation becomes the new normal practice. Researchers cite normalization of deviance as primary factors in the loss of the Challenger and the Chernobyl nuclear disaster.

Culture can magnify normalization by failing to correct the deviation or even encouraging it (“Oh, you had to do that in training, but no one really does it.”).

Normalization of deviance is particularly common in endeavors such as scuba diving that tend to have redundant safety practices to account for unintended and random human error. Nothing goes wrong because a redundancy accounts for the deviation — until one day the redundant factor is accidentally omitted, too.

If you find yourself skipping things you learned to do in training (such as predive safety checks), exceeding limits (diving deeper than you were trained to or entering overhead environments without training) or omitting gear you were trained to always have (such as snorkels or surface signaling devices), you’re exhibiting normalization of deviance. If you and your buddies reinforce these behaviors, you’re in a microculture that is normalizing deviation.

Because experience can reinforce normalization of deviance, experience is only a cure if something bad happens due to the deviation (and even then some divers go right back to the unsafe practices). The cure and prevention are the self-discipline to follow your training, honesty about the safety of your diving behaviors and refusal to listen to other (sometimes more experienced) divers who encourage deviations. AD DAN.ORG

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YOU’LL BE OK B Y

TH E

M O TH E R

O F

A

D EC EA S E D

D IVE R

THE DIVER

My daughter, who in this article will be referred to as Claire, was a 25-year-old planning dives on the West Coast. The dives would be her first since she completed her open-water certification two months earlier. She contacted the shop that certified her; they told her about an upcoming charter and assured her the dives would be within her ability. When she asked about a dive buddy, she was told she would be paired up on the boat. She mentioned that all her training dives had been from shore and that this would be her first boat dive. She was told a dive professional would be onboard to assist her, and she decided to join the trip.

THE DIVE

On the way to the dive site, Claire was introduced to her buddy, who will be called Jake. He had done 18 dives in his lifetime and had not been diving in more than a year. Almost all his previous dives were in the Caribbean.

As the boat approached the dive site, both divers expressed reservations when they learned the dive instructor onboard would be training a student rather than diving with them. They were told not to worry and that everything would be fine.

Jake had difficulty setting up his equipment and told the instructor his rental BCD was too tight, which made it hard for him to breathe. Once in the water, Claire was unable to descend, so the crew slipped additional weight into her BCD pockets. By the time these problems were resolved, the other divers had descended. Claire and Jake descended alone.

A plankton bloom, typical for the season and location, limited visibility near the surface. The divers overcame their anxiety by giving each other the OK sign repeatedly as they descended. At about 30 feet the visibility began to clear, but it was dark, and neither diver had a light.

About 10 minutes into the dive Jake turned to look at Claire, who had been swimming right behind him, and realized she was not there. After a moment he saw someone in the dimness and swam toward the person. As he approached, he saw it was Claire and realized she was unconscious. Grabbing her by her BCD, he attempted to ascend. He kicked hard but was unable to make progress toward the surface. He did not think to release her weights or inflate her BCD and was soon overcome with exhaustion. Jake struggled to get enough air through his regulator and began to panic. He released Claire and headed for the surface, spitting out his regulator on the way. He hit the surface gasping, choking and unable to call for help. The captain noticed him struggling and motored over to him. Unable to talk or breathe, Jake kept pointing down.

Once the captain realized there was a problem, he made a distress call and initiated a diver recall by tapping the boat’s ladder with a hammer. Not all divers responded to the call promptly, and some decided to do a safety stop before surfacing. Precious minutes were lost.

“Although it’s tempting Claire was found in approximately 60 feet of water by the instructor and to tell a new diver who is another diver. CPR was initiated once she was brought aboard, and a Coast Guard showing signs of anxiety boat arrived to transfer her to an ambulance on shore. Claire’s heart was started in “you’ll be OK,” reassurances, the ambulance on the way to the hospital, where she was placed on life support in the intensive care unit. however well-intentioned, Claire never regained consciousness. Three days after the accident the doctors may be fatal for unprepared determined she would never have enough brain function to breathe on her own, and we made the decision to discontinue life support. or inexperienced divers.”

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STEPHEN FRINK

DISCUSSION

Neither Claire nor Jake was sufficiently experienced for this dive. Claire had never dived without a professional guide, and she had not dived from a boat before. She relied on someone else to guide her through the process.

Jake had not dived for more than a year and did not take a skills refresher before the trip. He had never been taught what to do with an unconscious diver.

Jake had complained prior to the dive that his BCD was too tight and limited his ability to breathe. When Claire’s regulator was tested after the accident it was determined to be performing below the manufacturer’s specifications.

An inability to breathe properly may have contributed to both Claire’s unconsciousness and Jake’s sense of panic as he attempted to assist her to the surface. Whenever rental equipment is used, its fit and function should be assessed by the diver who will use it before he or she leaves the dive shop.

Dive operations should consider greater oversight and supervision of inexperienced divers, particularly when visibility is low and the divers are unfamiliar with the site or conditions. Neither Claire nor Jake had sufficient knowledge to evaluate whether the dive fell within the scope of their competence. Both divers relied on someone else’s opinion that the dive was appropriate for them. Claire lacked the experience to know what questions to ask, so she

trusted the dive shop employee who told her not to worry.

Jake expressed misgivings about his equipment and the lack of supervision prior to the dive. Despite this, he trusted the instructor who told him it would get better once they were underwater. Both divers decided to go ahead with the dive despite their apprehensions.

There were many opportunities for either Claire or Jake to have decided not to dive. New divers may not have adequate background to anticipate the potential for an accident, but every diver needs to have ingrained in them the notion that if they are not feeling good about a dive they should not get in the water. Divers must be honest with themselves about their ability to do any dive safely.

Before giving advice or assurances, a dive professional or experienced diver must be careful to evaluate the conditions from the perspective of a less-experienced diver. Although it’s tempting to tell a new diver who is showing signs of anxiety “you’ll be OK,” reassurances, however well-intentioned, may be fatal for unprepared or inexperienced divers.

New divers must be skeptical of others’ assessments and reliant on their own. If it feels like something is wrong, it very well may be. Take responsibility for your dive.

Problems on the surface are not likely to improve once you’re underwater. Whether it’s your fifth dive or your 5,000th, you have the right to call a dive. AD DAN.ORG

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SAFETY SERVICES

FREEDIVING SAFETY B Y

C H R I S

B U S TA D

PUSHING YOURSELF MENTALLY AND PHYSICALLY to overcome the challenges of a breath-hold dive can be a rewarding experience, but failing to make the appropriate safety considerations can have unfortunate consequences. If you prioritize personal safety, know your abilities, get proper training and dive only under direct supervision of other certified freedivers or safety divers, the odds are high that you’ll come out of the water ready to dive back in again.

PERSONAL SAFETY

JOAKIM HJELM

Unlike scuba diving, freediving doesn’t have a gatekeeper: Scuba divers can’t get an air fill or rent equipment without a certification card. Freediving, on the other hand, is open to anyone with access to a body of water. Humans have been freediving since someone looked into the water, saw something there that they wanted and went in after it. A significant number of freediving fatalities result from people diving without any formal training, so the challenge for freediving enthusiasts is how to encourage people to get training and reduce the number of injuries resulting from the sport.

People outside of the freediving community consider it to be a dangerous, extreme sport, but following proper safety protocols makes it quite safe. It is up to every member of the freediving community to recognize that diving alone or with an untrained buddy is unacceptable and to strongly encourage others to get proper training and dive safely.

I have been teaching freediving courses with Performance Freediving International (PFI) for more than five years, and one of the most common comments I hear from students is that they didn’t realize how dangerous freediving could be without a trained buddy or that having a lookout on the boat is not enough. Freedivers need to have eyes on each other on every dive and be close enough to intervene if needed. Proper training is key to recognizing a problem, being close enough to respond and knowing how to react and protect the airway of a freediver coming up from a dive.

A good buddy can retrieve you if you encounter a problem while freediving, but being overweighted could put you in a situation that even the most vigilant and highly trained buddy might be unable to manage. Students and untrained individuals “Humans have been often wear too much lead so that on the surface with a peak inhalation (their lungs completely full) they have to swim to keep their heads above the surface. If they freediving since someone were to lose consciousness after a prolonged breath hold, they would sink below looked into the water, saw the surface, possibly at an alarming rate. something there that they Many students try to justify being overweighted because they want to get to the wanted and went in after it.” bottom more easily. While we all want to get down easily and have a relaxing dive, 70 |

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A scooter freediver follows a spotted eagle ray. While recreationally freediving, it is important to stay within the limits of the divers you are diving with so if an issue occurs at depth they have the ability to assist you.

appropriate entry technique with correct weighting makes it even easier than loading up on lead. If you are properly weighted, you do not have to work as hard while diving.

Therefore, you conserve necessary oxygen and are much more likely to return to the surface without issue.

Surfacing is the most critical part of a vertical freedive for the obvious reason of needing to breathe air at the surface but also because the partial pressure of oxygen in your cells decreases as you surface from a freedive. Oxygen is depleted as you metabolize it to fuel your muscles to

move through the water; since you are holding your breath, you are not replacing the oxygen. The combined effects of you ascending and the pressure surrounding your body decreasing can cause you to lose consciousness. We call this a blackout, and 99 percent of blackouts happen either at the surface or within 16 feet of it. It is optimal to be weighted so that if a blackout occurs you will still end up at the surface. While blackouts seem daunting, freediving courses will teach you techniques to help you prevent blackouts. You will also learn how to respond to blackouts if they occur.

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SAFETY SERVICES

JASON WASHINGTON

Freedivers enjoy physical challenges and heightened connection with the environment while diving without life-support equipment.

LEARNING YOUR LIMITS

Proper weighting and buddy contact go a long way to preserve your safety, but both safeguards could be ineffective if you exceed the limits of your experience and training. The techniques learned in a course will help you dive deeper and stay longer, but freediving limits are based on your personal abilities, so listen to your body and learn what you can handle.

Freediving in a controlled environment, such as in a class, is different from going with a buddy or two, unsupervised by a professional, with a camera or speargun in your hand. Out on your own you must dive even more conservatively. When diving in a group, never dive deeper than any of your buddies can, and don’t expose the group to conditions that any member is uncomfortable handling.

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PROPER TRAINING

During the course, your instructor should provide a comfortable classroom that will facilitate learning and encourage questions. In confined water, you should be in a pool that is warm enough to comfortably learn in an appropriate wetsuit. For open-water training, your instructor should choose a site where everyone in the class can safely and comfortably enter, perform skills and exit. Instructors should cancel or reschedule sections if conditions are unsafe for the course level or for individual students who become seasick or get excessively cold.

Freediving instructors will encourage you to push yourself and perform outside of your comfort levels, but you should never feel pressured into doing something you do not want to do. If you choose not to perform a necessary skill, however, you will not get the certification.

In the end you will have a newfound respect for the water and the skills you need to freedive safely.

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COMPETITION SAFETY

JOAKIM HJELM

Responding to a blackout may seem intimidating, but it is a situation that any properly trained diver can manage.

Safety protocols during competitions are paramount so athletes can push their personal boundaries and set new records.

With deeper depths, longer bottom times or more strenuous dives, buddies may need to meet the diver at one-third their depth to ensure protection of the airway in case of an underwater blackout.

JOAKIM HJELM

ascent, the scooter safety can protect their airway and quickly get them to the surface. To protect themselves from the effects of decompression illness (DCI) during these rapid ascents from depth, scooter safeties will offgas by breathing gas with elevated partial pressures of oxygen at the surface, a technical freediving technique developed by Kirk Krack, PFI’s founder and CEO. Scuba safeties must not only have proper technical training and the experience to operate at these depths but also be well versed in freediving so they know what to look for and how to respond in a freediving emergency. They can use noisemakers to signal a problem and initiate the freediver recovery system or directly intervene by attaching a lift bag to the blacked-out or injured freediver, quickly sending him or her up the competition line to the surface.

The many facets of safety in freediving start with assuming personal responsibility. Never freedive alone, and always get training from a recognized agency to ensure your safety and the safety of the sport. AD JOAKIM HJELM

Some divers who have the determination to train and the physical ability can freedive at a competitive level, where safety precautions are paramount. Competitive freedivers prioritize their personal safety by consulting their coaches and announcing only performances they can realistically attain in the higher-stress environment of a competition.

It is common for athletes to train deeper than they plan to perform to remove some pressure of the competition.

The Association Internationale pour le Développement de l’Apnée (AIDA) and the Confédération Mondiale des Activités Subaquatiques (CMAS), the two leading organizations that oversee freediving competitions, have rules that competition organizers must follow. These rules ensure the safety of all athletes, safety divers, judges and spectators, and they keep the playing field even.

Some rules prohibit athletes from exceeding a maximum depth compared with their recent maximum depths, require use of a freediver recovery system or require athletes to return to the surface if they stop their descent. If someone breaks these rules or an incident occurs, teams of experienced and qualified safety divers are ready to make a rescue.

Safety divers (safeties), who have their own unique sets of rules that correspond to the rules for athletes, can be freedivers or scuba divers. PFI’s Deja Blue competition in Grand Cayman, one of the safest freediving competitions in the world, includes safety freedivers, deep scooter freediver safeties and deep scuba safeties to cover every zone of the athlete’s dive profile.

Most issues happen in the last one-third of the ascent, so freediver safeties go to one-third of the athlete’s announced performance depth and follow the athlete up from there. Other designated freediving safeties follow the athlete down on a scooter — at Deja Blue they go to depths of 196 feet (60 meters) to 230 feet (70 meters).

Should freedivers have an issue while deeper than the upper third of their prescribed maximum depth on

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STEPHEN FRINK

WHAT DROWNING REALLY LOOKS LIKE B Y M A R I O

The popular conception of what drowning looks like is not accurate. Unlike this photo, drowning people usually can’t call out for help, and there is very little splashing or waving.

Drowning is actually a very quiet and undramatic action.

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V I TTO N E

THE NEW CAPTAIN JUMPED from the deck fully dressed and sprinted through the water.

The former lifeguard kept his eyes on his victim as he headed straight for the couple swimming between their anchored sportfishing boat and the beach. “I think he thinks you’re drowning,” the husband said to his wife. They had been splashing each other, and she had screamed, but now they were just standing neck-deep on the sand bar.

“We’re fine, what is he doing?” she asked, a little annoyed. “We’re fine!” the husband yelled, waving him off, but the captain kept swimming hard.

“Move!” he barked as he sprinted between the stunned couple. Directly behind them, not 10 feet away, their 9-year-old daughter was drowning. Safely above the surface in the arms of the captain, she burst into tears and cried, “Daddy!”

How did this captain know from 50 feet away what the father couldn’t recognize from just 10 feet? Drowning is not the violent, splashing call for help that most people expect. Experts

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had trained the captain to recognize drowning, and he could draw on years of experience. The father, on the other hand, had learned what drowning looks like by watching television.

If you spend time on or near the water, then you should make sure that you and your crew know what to look for whenever people enter the water. Until the daughter tearfully cried out for her daddy after the captain rescued her, she hadn’t made a sound.

As a former U.S. Coast Guard rescue swimmer, I wasn’t surprised at all by this story. Drowning is almost always a deceptively quiet event. The waving, splashing and yelling that dramatic conditioning from television shows us rarely happens in real life.

The instinctive drowning response (IDR), named by Francesco A. Pia, Ph.D., is what people do to avoid actual or perceived suffocation in the water. It does not look like what most people expect. There is very little splashing, no waving and no yelling or calls for help of any kind. To get an idea of just how quiet and undramatic drowning can appear from the surface, consider this: It is the secondleading cause of accidental death in children age 15 and under, just behind vehicle accidents. Of the approximately 750 children who will drown next year, about 375 of them will do so within 25 yards of a parent or other adult.

In 10 percent of those drownings, the adult will watch but have no idea it is happening.

Drowning does not look like what we’re conditioned to think of as drowning. In an article in the Fall 2006 issue of the U.S. Coast Guard Search and Rescue’s On Scene journal, Pia described the instinctive drowning response as follows:

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the water permits drowning people to leverage their bodies so they can lift their mouths out of the water to breathe.

4. Throughout the instinctive drowning response, drowning people cannot voluntarily control their arm movements. Physiologically, drowning people who are struggling on the surface of the water cannot stop drowning and perform voluntary movements such as waving for help, moving toward a rescuer or reaching out for a piece of rescue equipment.

5. From beginning to end of the instinctive drowning response, people’s bodies remain upright in the water with no evidence of a supporting kick. Unless rescued by a trained lifeguard, these drowning people can only struggle on the surface of the water from 20 to 60 seconds before submersion occurs.

This doesn’t mean that a person who is thrashing and yelling for help isn’t in real trouble — they are experiencing aquatic distress. Not always present before the IDR, aquatic distress doesn’t last long, but unlike true drowning, these victims can still assist in their rescue.

They can grab throw rings or lifelines, for example.

Look for these other signs of drowning when people are in the water: • head low in the water, mouth at water level • head tilted back with mouth open • eyes glassy and empty, unable to focus • eyes closed • hair over forehead or eyes • not using legs — vertical position • hyperventilating or gasping • trying to swim in a particular direction but not making headway • trying to roll over on the back • appear to be climbing an invisible ladder

1. Except in rare circumstances, drowning people are physiologically unable to call out for help. The respiratory system was designed for breathing. Speech is the secondary or overlaid function. Breathing must be fulfilled before speech occurs.

2. Drowning people’s mouths alternately sink below If a crew member falls overboard and everything looks OK, don’t be too sure. They may look like they are and reappear above the surface of the water. The treading water and looking up at the deck. One way to mouths of drowning people are not above the surface of be sure is to ask them, “Are you OK?” If they can answer the water long enough for them to exhale, inhale and at all, they probably are OK. If call out for help. When the they return a blank stare, you drowning people’s mouths are may have fewer than 30 seconds above the surface, they exhale “The instinctive drowning response to get to them. Parents should and inhale quickly as their (IDR), named by Francesco A. Pia, know that children playing in mouths start to sink below the Ph.D., is what people do to avoid surface of the water. the water make noise. When actual or perceived suffocation in 3. Drowning people cannot they are quiet, get to them and find out why. Sometimes wave for help. Nature the water. It does not look like what the most common indication instinctively forces them to extend most people expect. There is very that someone is drowning is their arms laterally and press little splashing, no waving and no that they don’t look like down on the water’s surface. they’re drowning. AD Pressing down on the surface of yelling or calls for help of any kind.”

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SAFETY SERVICES

While dive boat passengers and crew members should take steps to eliminate potential causes of fire, one may still happen. Knowledge of the vessel and its safety preparations and procedures, as well as personal preparations, will help ensure the safety of everyone on board.

DIVE BOAT FIRE SAFETY TE X T B Y G U Y TH O MA S , D MT , A N D F R A N C O I S B U RM A N , P R . EN G . , P H O TO S B Y S TE P H EN FR IN K

M . S C .

TWO RECENT TRAGIC BOAT FIRES IN POPULAR DIVE REGIONS have once again illustrated that not all accidents happen during a dive. Although it appears that the fires started similarly, it will require in-depth investigations by the authorities to determine the actual causes.

What both accidents have in common is that there were casualties and the fires started at night.

Many divers wonder how to protect themselves against something over which they have little control. This article provides some background and advice to travelers who intend to take a dive boat excursion.

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VESSEL FIRE SAFETY

While rare, fires on dive boats can start from a variety of causes, including gas leaks, electrical faults and ignition of volatile fluids.

Boat owners are usually required to comply with local laws and regulations governing fire safety. They are also responsible for performing a fire risk assessment that focuses on possible causes, locations and the spread of fires. They need to mitigate the risk factors and develop and implement emergency action plans, including regular fire drills.

Passengers should consider the following: • Insist on a safety briefing, which includes life-jacket stowage instructions and what you should do in case of a fire.

• Check that escape routes and emergency exits are accessible and useable. Familiarize yourself with the operation of any doors or hatches, especially for accommodations that are below deck.

• Confirm that there are accessible and inspected portable extinguishers or some form of central overhead fire deluge system.

• Check if fire alarms and detectors for flames, smoke and carbon monoxide are installed and working, and ask when they were last tested.

• Find out if the staff maintains a watch system on board.

A crew member should be awake and on duty at all times to respond to emergencies and ensure boat safety. Know where to find this person. If you notice that they are asleep or not present, wake them up or find any available crew member. The lack of a watch is a serious matter that you should report to the crew member in charge or even the captain, depending on the size of the vessel. A watch system is especially important for fire safety, and it might be a Coast Guard requirement, depending on the location.

EVACUATION PROCEDURES

A fire can spread quickly. Smoke can swiftly reduce visibility to zero, and the toxins in the smoke can rapidly debilitate anyone. The heat generated can cause significant burns and prevent access to exits. Most victims in a fire succumb to smoke inhalation rather than burn injuries.

As soon as a fire is detected, everyone should react immediately and appropriately.

• Wake others, or activate the fire alarm as soon as you notice any fire or smoke.

• Don’t lose time searching for personal belongings. Even 30 seconds can make the difference between life and death.

• Remain calm.

• Don’t take suitcases or bags with you. They can hinder you and block the escape routes, making evacuation difficult or impossible for you and others.

• Help others during evacuation where possible and safe.

• Follow the crew’s instructions. They should be trained and

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equipped to contain a fire, rescue passengers and ensure your safety.

• If you see a fire inside a room, avoid opening any door or window. Fresh air adds oxygen and will rekindle a fire or increase its development and intensity.

• Never reenter a vessel that is on fire.

OTHER CONSIDERATIONS

Fires are a rare occurrence, but the consequences may be dire and often fatal. Consider the following suggestions when traveling: • Fire safety education and training in emergency procedures will be useful when dealing with a fire and help you to keep calm and remain focused.

• Keep a small (waterproof if on a boat) bag or container next to your bed. It should be just big enough to hold your passport, wallet and any medications you might need, but small enough that it won’t limit your movements or slow down the evacuation.

• If you wear glasses, keep them within reach so you don’t lose time looking for them during an evacuation.

• Do not charge batteries from flashlights, cameras (especially video cameras and lights), scooters and other large power consumers or charge devices such as a laptop, tablet or cellphone in your cabin when you are not there or while you’re sleeping. This is especially important if there is no smoke alarm.

• Do not overload an electrical outlet with too many devices.

This can lead to overheated extension cords, adapters or power strips, or it can cause an electrical overload, either of which can cause a fire.

• Pay special attention to your surroundings when smoking on board a dive boat. Flammable materials such as fuel, cleaning solvents and compressed oxygen are often present in restricted areas.

• Since the recent boat fires, some divers are purchasing portable carbon monoxide or smoke monitors for use in their cabins.

• If you are concerned about fire or smoke emergencies, consider bringing a small portable smoke hood to protect your eyes and lungs. Boat owners should consider providing them on board as well.

If you are traveling to dive, remember that fire risk is a concern not only while you are on the boat but also when you are in hotels or visiting dive centers. Fire safety and preparedness are important throughout your trip, both on board and onshore.

Are you a dive professional or dive operator? Participate in DAN’s Hazard Identification and Risk Assessment (HIRA) program to reduce the risks you might encounter in your dive business. For more information, visit DAN. org/HIRA. AD DAN.ORG

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SAFETY SERVICES

THE SOCIAL PSYCHOLOGY OF SAFE DIVING B Y

J A S O N

M A R TE N S ,

P H . D .

/

P H O T O S

B Y

S T E P H E N

FR IN K

AS CERTIFIED DIVERS, WE SHOULD ALREADY have a pretty good understanding of how to dive safely. But many of us have found ourselves in unsafe diving situations such as diving beyond our training or diving despite apprehension or discomfort. Many of these dangerous situations result from poor decisions made before a dive, but why do divers make bad decisions when we know better?

I have found myself in several unsafe situations in diving. Once a dive operator encouraged me to go on a dive that was deeper than I was trained to go. Another time one put together my equipment for me, and when I went to double check it he told me not to bother, saying they had “been doing this for years.” Many divers give in to this sort of pressure, but why does this happen despite all the training we’ve undergone?

We could say these dive operators have an unsafe dive culture, but I think we must examine how such cultures arise. Many factors contribute to unsafe diving. One is pluralistic ignorance, which is when people act as if nothing is wrong because nobody else is acting like anything is wrong. In diving, this can occur when someone suggests something unsafe and nobody speaks out against it.

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think something like “Well, nobody seems concerned, so maybe I’m paranoid; it must be OK.” We must not take the inaction of others to mean that everything is as it should be.

Another factor is known as diffusion of responsibility. This occurs when a person’s sense of responsibility diminishes in the presence of other people. In diving, we might see something that is inappropriate but say nothing because we assume it is someone else’s responsibility to say something. It is particularly easy for novice divers to fall into this trap since they tend to assume that everyone else is better suited than they are to take responsibility for the dive. Remember, you are the best advocate for your own safety.

Deindividuation is another factor that can lead to unsafe diving. This phenomenon is often called “being lost in the crowd,” but it doesn’t necessarily require a large group. We feel fewer constraints on our actions when many people are around us, as might be the case on a full dive boat. When we are lost in the crowd, we tend to act more impulsively and may thus be more prone to making errors.

Close-knit groups of friends can be particularly prone to groupthink, which is when everyone in a group agrees with each other without thinking things through.

Someone might suggest an unsafe dive, and everyone gives their assent without much thought.

On the other hand, diving with people you don’t know can also be problematic. We tend to want to be liked by others, so we sometimes do things we normally wouldn’t to get along or for others to like us. Often called normative social influence, it can encourage us to make an unsafe dive in an attempt to be liked by others. If someone suggests diving deeper than you are trained to, you might feel pressure to say yes if you want to be liked by that person. Although putting your life in danger just to be liked might seem strange, normative social influence is powerful and should be taken seriously.

Informative social influence is a bit different. This is when we do as others do because we think they know what is best. We learn from them and follow their lead.

This is a good thing as long as the person we are learning from is doing things properly. Unfortunately, novices often look toward anyone with more experience, but not every diver is a worthy role model.

The good news is that we can counter these unwanted influences in many ways, including reading articles like this one. The simple act of learning about these influences can be enough to weaken them. We can also do the following: • Take control. Don’t assume somebody else will say something is amiss. Review your training, and stick to it. If someone suggests doing something outside of your training, say you aren’t comfortable doing it.

Chances are that someone else in the group is similarly concerned but is too shy or uncomfortable to say so.

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• Slow down. We tend to act impulsively around other people, so slow down and think. Rarely do we have to make split-second decisions before we dive.

Taking a minute or even just a few seconds to think things through can effectively counter errors due to impulsiveness.

• Play devil’s advocate. It’s natural to blindly go along with the crowd at times. To counter this, think about what might go wrong. We won’t always identify plausible concerns when we play devil’s advocate, but sometimes we may notice potential problems.

• Rely on your training. Part of safe diving is recognizing unsafe diving. If you are unsure, consult your manual or ask a diver with knowledge, experience and a commitment to safe diving. You can often tell who these people are: They tend to talk about safety, have advanced training and help novices before dives.

• Model good behavior. If you are an experienced diver, lead by example. Don’t be afraid to go out of your way to make it clear you are a safe diver. For example, you might invite novices to plan their dives with you. This helps create a climate that benefits everyone.

• Role-play. Practice with a friend what you would do if someone pressured you to make an unsafe dive.

We often make poor decisions because we are put on the spot and don’t have time to think things through properly. Practicing what you would say and who you would say it to can make it considerably easier to make the safe decision. Prior to doing something exciting like diving, we tend to respond with our dominant response, but a beginner’s dominant response is not always the correct one. Through role-playing and practice you can make your dominant response one that supports safety.

Most of us understand, intellectually at least, the risks associated with cutting corners, rushing dives and not being fully prepared. By learning to recognize factors that lead to unsafe decisions, we can help keep ourselves out of dangerous situations. AD

Divers should be aware of the various ways social pressure can influence their behavior. When in doubt, rely on your training and never forget you are the best advocate for your own safety.

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SAFETY SERVICES

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WHEN THINGS GO WRONG EMERGENCY ACTION PLANS B Y

FRANCOIS

B U R M A N ,

P R .

E N G . ,

HISTORY TEACHES US THAT ACCIDENTS are always possible, thus we should have plans in place to mitigate them. Clients as well as staff, bystanders, dive professionals and the dive business itself are subject to risk.

Emergency action plans (EAPs) are essential tools for dive professionals and dive businesses. These plans typically provide information needed in case a dive accident occurs, although this consideration is usually limited to traditional diving activities or expected problems. Comprehensive EAPs must address a variety of risk areas, and few people understand what goes into identifying, compiling, reviewing and qualifying a truly effective EAP. This article is the first in a series that will cover the essentials of planning an effective and practical emergency procedure to help mitigate dive-industryrelated incidents. First we’ll consider where emergencies are likely to occur.

The risks vary by dive center, dive professional and area of operation, so we need a careful analysis to identify the real issues. Here is at least a partial list of possible risks to help identify areas of concern.

incapacitation of people; launch accidents; road accidents; hijacking of a vessel or vehicle Beyond the most readily identifiable risks are others that, though unlikely, warrant consideration and preparedness. These may be present in any of the areas listed previously or elsewhere: • a lost, abducted or wounded guest • unacceptable or aggressive behavior by a guest, staff member or visitor • sudden ill health or a medical emergency • criminal activity or arrest, death or homicide involving a guest or staff member An important location-specific aspect of emergency planning that should be addressed for all areas considered in an EAP is the availability and reliability of local emergency medical and law-enforcement services.

By illustrating these hazards and their potential locations, we hope to inspire dive businesses and self-employed dive professionals to think through their EAPs in greater depth.

There will always be risks, but with better know-ledge, understanding and preparedness we can reduce uncertainty and better contain the consequences of the hazards we will eventually face. AD PHOTOS BY STEPHEN FRINK

• At the dive center: fires; explosions of high-pressure cylinders, gas tanks or containers of hazardous fluids; contact with chemicals or other hazardous materials; injuries from electrocution; social unrest or other involvement with aggressive people

M. S C .

• At the pool and training areas: exposure to hazardous substances (such as chlorine); medical emergencies (including from preexisting health problems); injuries (from slipping, diving, falling or lifting heavy objects); drowning • While diving: traumatic injuries from propellers, ladders, slipping, diving or heavy objects, for example; encounters with hazardous marine life; lost divers; drowning; medical emergencies due to health conditions; entry and exit hazards associated with rocky shores or difficult-to-access caves or pools • During transportation (on land or on the water): fire; inclement weather; capsizing; loss or 80 |

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Available oxygen and trained staff are among the most crucial elements of emergency preparedness; Dive operators must be prepared for in-water accidents, but they must also be prepared for hazards unrelated to diving.

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RESEARCH 82 Matters of the Heart 87 Delay to Recompression 90 Timing Exercise and Diving 92 PFO and Decompression Illness 96 Checklists 98 Immersion Pulmonary Edema

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STEPHEN FRINK

MATTERS OF THE HEART AGING, WELLNESS AND FITNESS TO DIVE B Y

P E TA R

“Feelings of wellness do not necessarily coincide with physical fitness. People who do not do regular, vigorous exercise may discover their limitations in the face of a challenge — only when it is too late.”

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D E N O B LE,

M . D . ,

D . S C .

THE AGING OF THE DIVE POPULATION and an increased rate of cardiacrelated deaths with age in scuba divers are becoming important concerns to the dive community. In a favorable environment, scuba diving is a leisurely physical activity that many people choose for their lifetime or late-life recreation. Age is not considered a disease or a condition that necessarily disqualifies people from diving or any other physical activities, but it is associated with a decrease in functional capacity and an increased prevalence of chronic diseases. Criteria for medical fitness to dive have been defined and used with confidence for more than half a century. When it comes to physical fitness requirements for scuba diving, however, there is no consensus; divers are generally advised to evaluate the diving environment before each dive and avoid strenuous conditions that may exceed their physical capabilities. This approach seems to work for most divers except those who become victims of dive fatalities. Older divers are at greater risk of fatal

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accidents, and the most common cause of deaths in older divers is an acute cardiac event, which can be considered a sudden death. In this article we will briefly review the epidemiology of sudden cardiac death, age-related changes to the cardiovascular system, specific stressors in diving, the ways these may be related to dive fatalities and what divers can do to mitigate their personal risks.

SUDDEN CARDIAC DEATH

Sudden cardiac death (SCD) describes the unexpected natural death from a cardiac cause within a short time period (generally within one hour of symptom onset) in a person without any prior condition that would appear fatal. Such a rapid death is often attributed to a cardiac arrhythmia, but because 40 percent of sudden deaths may be unwitnessed it is impossible to tell with certainty.

SCD may be preceded by nonspecific symptoms such as chest pain (indicating ischemia), palpitations (arrhythmias) or difficulty breathing (indicating congestive heart failure).

In cases of ischemia or congestive heart failure, the heart

muscle fails, and in cases of arrhythmia the synchronization and timing of heart contractions fail. Both result in an inability to maintain circulation, loss of consciousness and, several minutes after circulation stops, death.

SCD occurs annually in 1 out of 1,000 adults in the U.S., accounting for more than 300,000 deaths each year. The risk of SCD in adults increases up to sixfold with age and parallels the risk of ischemic heart disease. Risk is greater in people with structural heart diseases, but in 50 percent of SCD cases individuals were not previously aware of heart disease, and in 20 percent no structural cardiovascular changes could be found during autopsy.

Divers with symptoms of cardiovascular disease should be evaluated by a cardiologist and a physician trained in dive medicine regarding their further participation. In people without symptoms, the risk of SCD may be evaluated using known cardiovascular risk factors like smoking, high blood pressure, high cholesterol, diabetes, lack of exercise and being overweight. For example, people who smoke have a risk of SCD two and a half times that of nonsmokers.

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BOB COAKLEY

MAXIMUM HEART RATE BY AGE Age (years)

20

30

40

50

60

70

80

90

Traditional estimate (220–age), beats per minute

200

190

180

170

160

150

140

130

Healthy nonsmokers (208–0.7 x age), beats per minute

194

187

180

173

166

159

152

145

Modified from Tanaka H. Age-predicted maximal heart rate. J Am Coll Cardiol, 2001; 37:153-6.

EFFECTS OF “HEALTHY” AGING ON THE CARDIOVASCULAR SYSTEM

We all know a team of young adults will usually outrun and outplay another team made up of middle-aged adults. Those in their 30s and older have already experienced a decline in their personal ability to sustain a high level of exercise for a prolonged period. Decrease of exercise capacity with “healthy” aging can be slowed down with regular exercise, but it cannot be avoided completely. The decrease in exercise capacity is caused by weakened functions of all the body’s systems, but we will keep our focus on the heart.

The heart has a natural pacemaker system that controls the heartbeat and the system of pathways that conduct signals to the muscle cells throughout the heart. Over time, the pacemaker loses some of its cells, and pathways may get damaged. These changes can result in a slightly slower heart rate at rest and susceptibility to abnormal rhythms like atrial fibrillation.

With age, all structures of the heart become more rigid.

The muscle of the left ventricle gets thicker, and the heart may increase slightly in size overall while the volume of the left ventricle may decrease. The heart may fill more slowly, empty more slowly and, thus, eject less blood into circulation.

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physical activity get slower, and the maximums get smaller (see table). The decreases in maximal heart rate appear to be an age effect, which is more pronounced in sedentary people and those with overt cardiovascular diseases.

The autonomic nervous system changes with age, too. Normally, the parasympathetic side sets the basic resting heart rate, while the sympathetic side affects the heart in anticipation of and in response to physical activity, stimulating timely and proportional increases in blood circulation necessary to support ongoing activity.

Continuous adjustment between the sympathetic and parasympathetic systems result in a heart-rate variability evident on a beat-to-beat basis, which is a sign of a healthy control system. With age, the contribution of the parasympathetic side wanes, the sympathetic activity increases (even at rest), heart-rate variability disappears and heart rhythm becomes more prone to derailments. Low heart-rate variability and increased resting heart rate (due to loss of parasympathetic tone) independently increase the risk of SCD more than two and a half times.

EFFECTS OF DIVING ON THE CARDIOVASCULAR SYSTEM

Diving exposes divers’ bodies to various stressors that independently affect cardiovascular function. The major

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stressors are immersion, exposure to cold, increased partial pressure of oxygen and increased work of breathing.

The combined effect of these factors is that the volume of blood in the vessels of the chest and heart increases significantly, stretching the walls of heart and large vessels.

Pressure in the right atrium and blood pressure slightly increase — more so in cold water. The heart has to work harder to maintain circulation. These conditions contribute to various arrhythmias, from bradycardia (slow heart rate) caused by cold to tachyarrhythmia (racing heart rate) caused by cardiac and neuroendocrine responses to stress.

Older people, especially those with structural cardiovascular changes and weaker function, are at greater risk of adverse reactions to these stresses.

The autonomic nervous system is affected by diving, too. In healthy individuals, diving increases parasympathetic effects on heart rate, and heart-rate variability is preserved.

Diving that is perceived as stressful pushes the balance of the autonomic nervous system in the other direction: Sympathetic effects prevail and increase the heart rate, diminish heart-rate variability and increase the risk of arrhythmia.

Although diving is often perceived as a leisurely activity, the level of exertion may sometimes exceed the physical capacity of divers with functional limitations as well as healthy but older divers. In weightless conditions of immersion, muscular work is less punishing and divers easily exert themselves beyond their cardio-respiratory limits.

Most divers regard swimming against a 0.5-knot current as a challenge. Heart rates measured in trained military divers during shallow underwater swimming increased to an average of 101 beats per minute (bpm) in a 0.6-knot current and to an average of 141 bpm in a 1.2-knot current.

For many divers this would exceed a sustainable level (which is usually considered to be less than 80 percent of the maximal heart rate). Even more important, divers who do not regularly practice swimming and do not master the technique of underwater swimming with fins as well as those who do not streamline their gear and especially those whose buoyancy is a bit off, would probably reach their maximal heart rate while swimming even more slowly. Some may reach their limit just trying to stay afloat.

WHAT ARE THE RISKS?

Fatality statistics indicate at least one-third of all dive fatalities are related to an acute cardiac event. The risk of cardiac-related death in divers is continuous, steadily increasing with age; divers older than 50 have a risk 10 times that of divers under 50. While some suspected cardiac events may be provoked by specific dive effects, some may be not related to diving at all, as sudden cardiac deaths occur in swimming, land-based sports, at rest and during sleep.

An acute myocardial infarction (heart attack) due to exertion while swimming against current, waves or excessive negative buoyancy is probably quite common among dive-provoked fatalities. It is caused by insufficient blood supply to working heart muscle. This occurs most commonly in middle-aged male divers unaware of their coronary artery disease.

It is also reasonable to expect diving could provoke an acute arrhythmia, which might result in sudden death.

The arrhythmia is a more likely cause of death for older divers. As Carl Edmonds, M.D., describes and DAN data confirm, “The victim often appeared calm just before his final collapse. Some were unusually tired or resting, having DAN.ORG

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previously exerted themselves, or were being towed at the time — suggesting some degree of exhaustion. Some acted as if they did not feel well before their final collapse.

Some complained of difficulty in breathing only a few seconds before the collapse, whereas others underwater signaled that they needed to buddy breathe, but rejected the offered regulator. Explanations for the dyspnea include psychogenic hyperventilation, autonomic-induced ventilatory stimulation and pulmonary edema — the latter being demonstrated at autopsy. In all cases there was an adequate air supply available, suggesting that their dyspnea was not related to equipment problems. Some victims lost consciousness without giving any signal to their buddy, whereas others requested help in a calm manner.”

SCD occurs at comparable rates and a nearly identical age-related pattern in diving and in the general population, but a causative relationship between diving and SCD should not be dismissed. SCD cases without an obvious external provocative factor are more common in older divers. Medical examinations in such cases reveal signs of heart disease rather than identifying a specific event that caused SCD. Outcomes of these diving fatalities might not be different than SCD cases in the general population except the divers usually do not have a chance of being resuscitated. The best way to avoid SCD is to prevent heart disease and maintain wellness and physical fitness despite aging.

FITNESS AND WELLNESS PROGRAMS

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WELLNESS

Wellness may be defined in various ways, but it is in essence a subjective state of satisfaction with one’s present condition, which depends greatly on underlying health and, at the same time, helps improve health. One example of a practice that may help individuals achieve wellness is yoga. Yoga seems to affect flexibility, posture, balance and muscular strength. Relaxation and breathing techniques seem to reduce overall sympathetic tone in older adults, increase parasympathetic effects on heart rate and potentiate heart-rate variability. Regular yoga practice reduces anxiety and improves overall wellness.

Feelings of wellness do not necessarily coincide with physical fitness. People who do not do regular, vigorous exercise may discover their limitations in the face of a challenge — only when it is too late. For enthusiastic divers, diving may be very important for achieving wellness. To promote continued fitness for diving, divers should maintain a healthy lifestyle, exercise regularly, practice specific skills for diving, use all means to achieve wellness and make wise choices in diving. AD

STEPHEN FRINK

Physical fitness is the ability to move in a physical world and change it by muscular effort. There are many components to it; the main one is a capacity to conduct aerobic work. Good health and fitness in older age is a matter of absence of disease, lifelong healthy habits and fitness maintenance. Adopting a healthy lifestyle at any age will improve quality of life, but a return to the normal curve of fitness and longevity is probably proportional to previously acquired insults. According to recommendations of the American College of Sports Medicine (ACSM) and the American Heart Association (AHA), regular physical activity, including aerobic activity and muscle-strengthening activity, is essential for healthy aging. The U.S. Department of Health and Human Services published physical activity guidelines that can be found at Health.gov. Benefits of exercise are many, and they are dose dependent: The more one exercises, the greater the benefits are. These include reduced risk of cardiovascular disease (and thus, SCD), tromboembolic stroke, hypertension, type-2 diabetes, osteoporosis, obesity, colon cancer, breast cancer, anxiety and depression. The ACSM and AHA maintain that with sufficient skill, experience, fitness and training, older adults can achieve high levels of physical activity. At the same time, for some

older adults, age-related fitness loss, chronic diseases and functional limitations act as barriers to attaining high levels of activity.

While the health benefits of physical activity may be achieved with low to moderate levels of exercise, this may not increase aerobic capacity or improve fitness for swimming against a strong current. A high level of aerobic fitness may be acquired and maintained only by regular vigorous exercise, as approved by physician. Fitness for swimming against a current includes fin-swimming skills.

Divers without these skills may not be able to create sufficient propulsion to overcome strong current despite their high aerobic capacity for muscular work. Thus, part of divers’ exercise must be dedicated to fin swimming.

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STEPHEN FRINK

DELAY TO RECOMPRESSION BY

P E TA R

D E N O B LE ,

M . D . ,

D . S C .

THE MOST EFFECTIVE TREATMENT FOR DECOMPRESSION SICKNESS (DCS) and arterial gas embolism (AGE) caused by gas bubbles that occur after decompression is the return of the patient to an environment of increased pressure. This is called recompression. Ideally a patient can be recompressed within minutes of symptom onset — bubbles would be quickly eliminated, and symptoms would resolve. This occurs sometimes in commercial and military diving. However, in recreational diving, even when a chamber is available locally, it generally takes hours rather than minutes to begin recompression treatment. If a hyperbaric chamber is not available locally, which is often the case, recompression may be delayed for days. For divers in remote locations, the question of the impact of the length of delay to recompression on their chances of a complete recovery is an important one. In asking this question, it is also important to explore steps that can be taken to mitigate risks. The available data do not provide straightforward answers, so we turn to experts for advice.

What determines the degree of emergency in DCS? Dr. Jordi Desola: The degree of emergency in cases of DCS is determined by the severity of its presentation. Severe cases involve several organ systems and may involve impaired circulation, breathing and consciousness. Such cases can result in permanent disability or death.

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Dr. Karen Van Hoesen: The following responses represent the collective opinions of the University of California San Diego (UCSD) Hyperbaric Medicine Center physicians. These opinions are based on review of the literature and our collective experience of treating divers with DCS for more than 30 years. In general, the degree of emergency in DCS is determined by 1) the time to onset of symptoms following the dive, 2) cardiopulmonary instability and 3) rapidly progressing neurologic symptoms. The quicker the onset of neurologic symptoms after a dive (including motor and cerebellar symptoms and mental status changes, but not including sensory deficits alone), the more serious the DCS insult.

Any evidence of cardiopulmonary instability with DCS is a true emergency. Neurologic symptoms that present quickly and rapidly progress are also an indication of serious DCS and should be considered an emergency.

AGE with neurologic symptoms is a true emergency and is excluded from the responses that follow.

In your opinion, starting at six hours after symptom onset, how much additional delay to recompression may affect the outcome of DCS? Van Hoesen: Based on very limited case reports and data, it appears there is a subset of moderate to severe DCS cases where early treatment within six to 12 hours may improve outcome. However, this subset of individuals with DCS has not been clearly defined. The severe cases described above may make up part of this subset.

Regardless, there are numerous cases of DCS that show improvement even with significant delay to treatment beyond 24 hours.

Desola: I have worked in Barcelona’s hyperbaric unit for more than 30 years and have treated several hundred DCS cases of various severities and with various delays to treatment. In 1977 we started a prospective study to explore what affects the outcome of treated DCS. The first analysis of 466 cases, presented in 1997, showed that delay in recompression was not significant. Three years later and with more cases (554), a comprehensive statistical analysis revealed that clinical findings are the most important prognostic factors for DCS outcome. Our findings were not very popular because they went against current beliefs at that time. Since then, several reports from reputable hyperbaric centers have confirmed them.

A recent retrospective study in the French navy found that 25 percent of divers with DCS had incomplete resolution after one month despite a short delay to recompression (median 35 minutes). Longer delays apparently did not significantly increase the risk of incomplete resolution.

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aggressive rehydration, hyperbaric oxygen therapy and critical care assistance inside the chamber when necessary.

Might the effects of a delay to recompression affect severe and mild DCS differently?

Desola: Experience suggests that the more serious the signs or symptoms, the worse the prognosis, regardless of the delay to recompression. It was believed more severe cases could be completely resolved if recompressed within the first few minutes, but this is rarely possible, even in military or professional diving and never in recreational diving. On the other hand, most mild cases resolve completely regardless of treatment delay.

Intuitively, recompression must be applied as soon as possible, within the rational local limitations. This is the message that must be given to divers at all times. However, today we know of many divers recovering satisfactorily despite having received hyperbaric oxygen therapy (HBOT) hours or even days after onset of the symptoms. In contrast, there are also cases of DCS with a poor outcome despite being treated within few hours after symptom onset.

Van Hoesen: It may. As described above, there is probably a subset of patients with more severe DCS that do better with early treatment. The natural history of mild DCS is that it tends to improve with time regardless of time to treatment. HBOT should still be considered the standard of care for all cases of DCS. Considering the increased risk of accidents with unscheduled flights, what conditions must a patient meet for you to decide to use an emergency air evacuation versus a scheduled flight on a commercial aircraft or ground transportation?

Van Hoesen: Each case of DCS needs to be considered individually and should be discussed with a DAN® medic or consulting physician. Anyone meeting the criteria for severe DCS described above should be considered a candidate for emergency air evacuation.

Ground transportation for individuals with mild, painonly DCS may be suitable. Flying on a commercial airliner with mild, pain-only DCS might also be the most appropriate approach, depending on the situation.

Desola: If divers’ vital functions are stable and no lifethreatening complications are expected, they may be transported with a scheduled flight on a regular airliner.

This includes cases of skin and muscular DCS, mild neurological DCS and even spinal cord DCS in which the lesion is likely incomplete, affecting only mobility and/or sensitivity of the limbs without causing bladder or bowel paralysis. The patient must be in stable condition. Also, the patient must be rehydrated before transportation and

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should breathe oxygen during transportation. In cases of pulmonary barotrauma with pneumomediastinum or pneumothorax, divers should not travel aboard a regular airliner due to the risk of life-threatening conditions from further expansion of gas trapped within the chest.

If divers with DCS symptoms have no chance of reaching a hyperbaric chamber without delay, what should they do in the meantime?

Desola: This is a difficult question; a very detailed and complete evaluation over the phone or via video conference is essential. The procedure will be different depending on the assessed seriousness of the diver’s injury.

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3. In the hospital, a physician will apply necessary emergency procedures to ensure the patient’s survival.

DAN emergency medical services should be contacted (+1–919–684–9111), and the best procedure regarding hyperbaric treatment should be decided. In some cases it may include a medical air evacuation to the most appropriate hospital when the patient’s status permits it.

Van Hoesen: Divers with DCS symptoms should breathe surface oxygen if available. If the diver is conscious, awake and alert, he should drink fluids and stay well hydrated.

If pain is the only symptom, taking a nonsteroidal antiinflammatory medication such as ibuprofen or naproxen can be considered. The diver should avoid alcohol intake.

Do not initiate in-water recompression. AD

NONCRITICALLY INJURED DIVERS

Injured divers who are in stable condition and whose symptoms are no more severe than muscle pain, fatigue, mottled skin or impaired sensation in an extremity can be considered noncritically injured. These patients must not have any serious symptoms such as bowel or bladder paralysis.

1. A local physician or medical facility, if available, should be contacted to examine and evaluate the diver.

2. If no medical help is available locally, a detailed phone evaluation should be conducted.

3. Provided the injured diver is conscious, oxygen and oral rehydration should be administered, and a low dose of an anxiolytic and/or analgesic could be considered if needed.

4. An air evacuation should be organized using the first available commercial or private aircraft. The patient should be transported to a hyperbaric facility that can provide adequate medical care. The facility should be within a hospital and so may not be the nearest hyperbaric chamber.

5. Telephone contact with the target hospital-based hyperbaric facility must be initiated.

NOTE: Regardless of the opinions expressed herein, each case of DCS should be discussed on an individual basis with DAN medical staff to ensure proper diagnosis, treatment and evacuation, if indicated. Additionally, these opinions are for recreational divers and do not apply to technical, mixed-gas, commercial or saturation divers.

MEET THE EXPERTS Jordi Desola, M.D., Ph.D., is the head of the Hyperbaric Therapy Unit of the Red Cross Hospital of Barcelona (Catalonia, Spain). His specialties are internal medicine, occupational medicine and sports medicine. He is professor of diving and hyperbaric medicine at the University of Barcelona, cofounder of DAN Europe and a permanent member of the executive committee of the European Committee for Hyperbaric Medicine (ECHM). He was chairman and president of the 15th International Congress on

CRITICALLY ILL OR INJURED DIVERS

Hyperbaric Medicine (ICHM) in 2005. He is also a

This applies to cases in which there is bladder paralysis, shock (low blood pressure, hemoconcentration and hypovolemia), possible changes in consciousness or respiratory failure. This includes severe cases of DCS as well as AGE caused by pulmonary barotrauma and nonfatal drowning.

1. Confirm the diagnosis, and re-evaluate the severity of the injured diver’s clinical condition.

2. Transfer the seriously injured diver to the nearest available hospital that can provide qualified evaluation and proper emergency care despite the fact that a hyperbaric chamber with an experienced hyperbaric physician may be closer.

diving instructor and a pilot.

Karen Van Hoesen, M.D., is the director of the University of California San Diego (UCSD) Diving Medicine Center and Undersea and Hyperbaric Medicine Fellowship. She is a clinical professor of emergency medicine in the UCSD Health System and has authored numerous papers and book chapters on diving and hyperbaric medicine.

She is an active diver and one of DAN’s on-call consulting physicians.

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TIMING EXERCISE AND DIVING

DAN MEDICS AND RESEARCHERS ANSWER YOUR QUESTIONS ABOUT DIVE MEDICINE.

Q: A:

How is a dive professional supposed to stay in shape when we’re advised to avoid vigorous exercise within 24 hours of diving? What kind of exercise is recommended for a divemaster or instructor who dives daily?

The problem you describe is, unfortunately, something of an intractable one. There is no easy solution. A compromise is almost always required. The simplest rule is that the highest-intensity exercise should be separated from diving, particularly from more extreme dives.

Some runners run every day regardless of other activities. The first recommendation for such people is that they dive very conservatively. This advice is by itself a problem since it is difficult to quantify “conservative,” and the spirit of the recommendation is not generally understood in the diving community. Diving within the limits of a dive computer or table does not necessarily constitute conservatism. There are a variety of different limits, and many divers have developed symptoms while adhering to them. Computers or tables provide estimates for a variety of people and exposures based on limited input.

A major challenge in appreciating the risk of decompression sickness (DCS) is its probabilistic nature. The fact that a diver might tolerate a given exposure once, twice or 10 times without incident doesn’t mean the exposure is safe. If DCS results from the 100th exposure, this is not an undeserved hit — the diver simply ended up on the wrong side of the probability line that day.

Humans have a tendency to let good habits erode when nothing bad happens. We tend to increase our driving speed and push depth and/or time limits on dives. Furthermore, we often fail to appreciate that we are not being as conservative as we once were. This can lead to surprise when things go bad.

This surprise can create a tendency to look for some factor to blame. With DCS, dehydration is often the scapegoat. The reality in most cases is that a similar state of hydration probably existed on many other dives. The real problem with this tendency is that it may encourage the diver to ignore the depth-time profile, which is by far the most important factor.

While it can be comforting to identify a simple cause, it is a disservice to safety. The risk of DCS is affected by a large number of factors acting in complicated concert. True conservatism is required to increase the likelihood of consistently safe outcomes.

The daily runner will have a sense of the normal pains and discomfort associated with their exercise. Atypical pain or discomfort in a diver will raise suspicion of a decompression injury.

Again, the ideal choice for this person would be to limit diving to conservative exposures. The next best choice would be to fit in the intense physical activity as far from diving as possible. It is safest to limit physical activity to that with very low joint forces — the closer to diving, the lower the forces. Modest swimming, for example, involves much lower joint forces than running.

Cycling can also involve lower joint forces than running. These are not absolutes, though. It is not enough to choose an activity that might have low joint forces; it is necessary to practice it in a way that ensures low joint forces.

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The practical approach is to separate physical activity from diving, with the lowest-intensity exercise closest to the diving. Swimming and walking typically produce less strain than intense cycling or running. High and repetitive joint forces should be minimized. The diver should be mindful of the activity level and honestly appraise the risk. By making small decisions that consistently favor the slightly safer option over the slightly more aggressive, an adequate safety buffer can be created.

This is not a simple answer, but reality is messy. Exercise, especially intense exercise, can increase the effective decompression stress. If it is not avoided, an honest appraisal of conditions and actions is important to control

the risk. If a problem does develop, it is best to skip the denial and blame phases. DCS can and does happen, often following dives that were assumed to be safe.

Ultimately, each diver should appreciate the risks, work to control them and accept that diving involves complicated hazards. Getting bent should not be considered a personal failing. Being open to the possibility of DCS can start a diver down a very positive road of preparedness and action to reduce risk at every opportunity. Employ physical activity thoughtfully; ultimately the self-aware and self-critical (honest) diver will likely end up being the safest one. AD — Neal W. Pollock, Ph.D. DAN.ORG

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PFO AND DECOMPRESSION ILLNESS IN RECREATIONAL DIVERS T O P M E D I C A L R E S E A R C H E R S D E B AT E T H E R I S K S O F T H E C O N D I T I O N A N D T H E T R E AT M E N T B Y

P E TA R

D E N O B LE,

M . D . ,

D . S C .

PATENT FORAMEN OVALE (PFO) IS A RELATIVELY BENIGN CARDIAC DEFECT that creates a passage in a wall that normally separates the left and right upper chambers of the heart. PFO is found in about 25 percent of adults, most of whom will never know they have it. The passage may open in certain circumstances and enable venous blood to pass through to the arterial side of the heart; this is a unique concern for divers. If gas bubbles form after a dive, the venous bloodstream will carry them to the right side of the heart. In divers with PFO, the bubbles could pass through the opening, bypassing the lungs and theoretically putting the diver at an increased risk of decompression sickness (DCS).

A number of retrospective studies have established that the incidence of PFO is two to six times greater in divers who experience a neurological DCS hit; however, these studies do not prove PFO is the cause of DCS symptoms. The only prospective study designed to measure how PFO affects the risk of DCS is ongoing. A similar association without causative relation was established for PFO and migraines as well as PFO and coronary heart disease. These conditions may be inherited in a similar way and thus may appear in the same people, but they do not necessarily cause each other. Many divers who get DCS do not have a PFO, and many divers with a PFO do not get DCS. Even if PFO is a risk factor for DCS, the risk is very small due to the low incidence of DCS. The risk can be additionally reduced by avoiding dive profiles that are likely to generate a lot of bubbles.

It is reasonable to expect that closing the PFO would reduce the risk of DCS; however, there are no consensus criteria for PFO closure in divers. Divers have been undergoing transcatheter closures for years, but an evidence-based risk-benefit analysis is not available, and PFO closure as a means to prevent DCS remains controversial. Most diagnosticians recommend the procedure only in cases of repeated “undeserved” DCS — or DCS occurring without clear causative factors — involving the skin, brain or inner ear. To shed light on this poorly understood topic, we asked recognized experts to provide their opinions regarding three questions of interest for divers concerned with PFO testing and PFO closure.

Should divers be tested for PFO? Dr. Alfred Bove: There is no indication for a diver to have a routine screen for a PFO. A PFO is present in 25 to 30 percent of all people. DCS is caused by excess supersaturation of inert gas with subsequent bubble formation in blood and in tissues, and not by a PFO. Bubbles in the venous blood may cross a PFO, but there are many cases of DCS in divers without a PFO, so other factors need to be considered. Several studies have shown that a PFO will increase the risk of DCS; however, the DCS risk remains miniscule even with a PFO. The most common neurological manifestation of DCS 92 |

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is spinal cord injury, and the correlation of this disorder with a PFO is weak, as is the relation to musculoskeletal DCS.

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Dr. Peter Germonpré: No. PFO is so common, and decompression sickness is so rare that the systematic testing for PFO would cause more concern than it would have any benefit. There are other shunts of blood possible (e.g., at the level of the lungs), and there are other factors that may promote DCS. All divers need to be aware that any decompression bubbles, when present, may provoke DCS, and they should dive so as to minimize those bubbles.

Dr. Richard Moon: It is important to keep in mind several issues. First, the relationship between PFO and DCS is an association.

While there is a plausible explanation for the apparent connection (i.e., DCS triggered by arterial bubbles), this is not yet proven. Indeed, PFO has not been linked to the most common symptoms such as pain-only bends, numbness, tingling or fatigue. Second, PFO exists in 25 to 30 percent of people, and studies have shown that venous bubbles are extremely common after recreational dives. Therefore, many divers must be experiencing arterial bubbles, yet DCS is extremely rare (especially the more serious variety that is associated with PFO). Third, if the bubble explanation is correct, a PFO could precipitate DCS only after a dive of sufficient depth and duration to generate venous gas embolism. PFO is therefore unlikely to be a factor for mild DCS cases or ones that occur after short exposures or shallow depths (i.e., “undeserved”). Finally, most cases of DCS occur in divers without a PFO. It is difficult or impossible in an individual diver to ascribe a particular DCS occurrence to a PFO, as PFO will exist in nearly one-third of cases even if there is no causal relationship. Therefore, testing for a PFO is useful only in instances where there have been several DCS incidents of a type known to be PFO-associated, and the person cannot modify depthtime exposures or breathing gas.

What is an acceptable indication for PFO closure in divers?

Germonpré: If a diver has suffered DCS, a systematic search for possible contributing factors should be undertaken. This involves analyzing the dive and circumstances around it and also medical factors such as PFO or pulmonary abnormalities. If any of these factors

are found, a suitable preventive strategy may be advised.

Current statistics indicate that the possible risks of PFO closure are much larger than the risk for DCS when diving within no-decompression limits. In a few years we may have precise figures when the prospective Carotid Doppler Study from DAN Europe is concluded. There are measures that can be taken to decrease further the DCS risk in recreational diving such as diving nitrox on air tables. Therefore, we recommend PFO closure only in specific cases: DAN.ORG

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• professional divers, who are required to dive with imposed dive profiles and cannot adapt their diving behavior • sport divers where no other contributing factors for DCS could be identified and who [experienced DCS after] a “low-risk” dive profile In any case, the decision to close a PFO must be taken only after thorough information review, analysis of the risks and explicit consent.

Moon: A commercial diver (e.g., offshore worker, dive instructor) who has experienced several DCS incidents of a type known to be associated with PFO (e.g., neurological), and who is not in a position to increase the oxygen percentage in his/her breathing gas or modify depth-time exposures [might consider PFO closure].

Bove: I would not recommend PFO closure in any sport diver, whether or not the diver had a DCS incident. The noted incidence of DCS in recreational divers is between two and five cases per 10,000 dives (0.02 percent to 0.05 percent). The serious complication rate for PFO closure, as noted in Dr. Douglas Ebersole’s comments (see sidebar), is 3-4 percent, more than 100 times the risk of experiencing a DCS event. It is clear that the risk-benefit ratio for PFO closure in divers strongly favors not closing the PFO. Further, the presence of a residual PFO after closure is significant, up to 30 percent in some studies.

deep saturation dives, and the frequency of symptoms was reduced after PFO closure. So there are likely to be occasional cases where PFO closure would be warranted in a diver, but this would not apply to recreational divers.

Germonpré: After PFO closure, one of the possible shunts from right to left has been eliminated. There is, however, no guarantee that closure is successful, and even if no shunt remains, some divers keep having recurrences of DCS, probably because other shunts open. In our experience, minor complications (cardiac rhythm disturbances, migraine attacks, bleeding) are not so rare. The long-term outcome of these devices has not been defined; most of the current devices have been on the market only a number of years. The presence of a “foreign body” inside the heart wall may, with age, cause other and more serious cardiac troubles. Finally, it is rarely possible to pinpoint one single cause for DCS; remedying one single factor does not “immunize” a diver from DCS. AD

MEET OUR PANEL Alfred A. Bove, M.D., Ph.D., is the former chief of cardiology at Temple University Medical Center in Philadelphia, Pa., emeritus professor of medicine and the immediate past president of the American College of Cardiology. He has authored texts on

If divers consider PFO closure, what risks and benefits do they have to take into account?

Moon: The benefit cannot be absolutely predicted, as in a particular diver it is not possible to ascribe DCS to a PFO with certainty. PFO is only one of probably several individual factors that may confer an increased risk of DCS, although most such factors have yet to be discovered. No invasive medical procedure is entirely without risk, and PFO closure is no exception. Even though the risk is low, a diver must balance it against an uncertain benefit. Other methods, such as reducing depth or bottom time, or using enriched oxygen mixtures, are safer.

coronary disease, exercise medicine and dive medicine. He maintains an active clinic cardiology practice, with emphasis on heart failure and cardiac transplantation, sports cardiology and undersea and hyperbaric medicine.

Peter Germonpré, M.D., is the medical director of the Centre for Hyperbaric Medicine of the Military Hospital in Brussels, Belgium. He is also the DAN Europe (Benelux) medical director and senior researcher of the DAN Europe Research department, where he coordinates the DAN Europe PFO studies.

Bove: Most DCS cases with or without a PFO are related to excess exposure to depth and time. Diving within the no-decompression limits will have a much greater effect on reducing the incidence of DCS than will closure of a PFO. The risks of closure are well explained in Dr. Ebersole’s comments. There is little knowledge of the long-term effects of implanting the device. Some cardiologists feel that the presence of a PFO occluder would prevent the use of a very effective method for treating atrial fibrillation (catheter ablation). There have been several case reports of commercial divers who experienced repeated incidents of DCS following 94 |

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Richard Moon, M.D., has been associated with DAN since its formation, first as medical director and then as senior medical consultant. He is a professor in the departments of anesthesiology and medicine at Duke University Medical Center in Durham, N.C., and medical director of the Duke Center for Hyperbaric Medicine and Environmental Physiology. In 1989 he published the first analysis demonstrating a link between serious decompression illness and PFO.

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PFO: YOUR QUESTIONS ANSWERED BY

DOUGL AS

EBERSOLE,

M. D.

What is a PFO? A patent foramen ovale (PFO) is an incompletely sealed wall between the right and the left atria (see illustration). Prior to birth, this wall develops from the septum primum, which grows upward, and septum secundum, which grows downward. These septa overlap, providing a “trap door” (the foramen ovale), which allows oxygenated blood from the mother’s placenta entering the right atrium to pass to the left atrium. At birth, the lungs expand and the pressure in the left atrium “slams shut” the foramen ovale. Shortly after birth, the “door” fuses in most people, but in about 27 percent of people it fails to fuse completely and results in a PFO. The prevalence of PFO in divers with DCS is two times greater than in the rest of the population.

In divers with neurological DCS, it is four times greater. The risk of DCS seems to increase with the size of the PFO. Based on these statistics, it is assumed that divers with PFO are at greater relative risk of DCS than divers without PFO; however, the only prospective designed to measure directly the relative risk for DCS in divers with PFO is ongoing.

How is a PFO diagnosed?

The diagnosis is made by injecting a small amount of air into a vein and observing its passage through the heart by echocardiography. An echocardiogram is performed by placing the ultrasound probe on the chest. Transthoracic echocardiography (TTE) is easy and noninvasive, but it detects a PFO in only about 10-18 percent of the population, around half of those who may have it. Transesophageal echocardiography (TEE), where the probe is passed into the esophagus after local anesthesia and intravenous sedation, detects PFOs in 18 to 33 percent of the population. Even if TEE is more sensitive than TTE, there are many “false-negative” results with both techniques, and it is important to realize that a well-conducted TTE with a proper technique may be more reliable than a TEE. What is transcatheter PFO closure?

Transcatheter PFO closure is the implantation of an occluder device across the PFO through a catheter inserted via the femoral vein in the groin. The occluders come in various shapes and forms, but most act like a double umbrella that opens on each side of the atrial wall and seals it. With time, tissue grows over and completely covers the occluder surface. The implantation procedure is performed in patients under local anesthesia and intravenous sedation while the patient remains conscious. It

takes less than one hour and can be performed on an outpatient or one-night-stay basis. Most patients can return to normal activity in two days, but they must take anti-coagulation medication and blood thinners for three to six months. Other restrictions include: no elective dental care (such as cleanings) for three months, no contact sports for three months, and no heavy lifting for one week. After implantation, divers must abstain from the sport for three to six months.

What are the outcomes of transcatheter PFO closure?

Note: Due to the lack of data in divers, we present outcome data in patients undergoing PFO closure for the prevention of stroke. These patients have underlying medical conditions that may contribute to adverse outcomes.

Efficacy • Complete closure of shunt: 95% • Incomplete closure: 4 to 5% • No improvement of shunt: 1 percent Complications • Overall mortality: 0.093 percent • Rescue operation for device adverse events: 0.83% • Serious complications — death, stroke, infection, bleeding, blood vessel injury: 0.2% — device movement or dislodgement: 0.25% — clot forming on device: 0.3% — major periprocedural complications: 1.2% — minor midterm complications: 2.4% DAN.ORG

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STEPHEN FRINK

CHECKLISTS KEYS TO SAFER DIVING? B Y

S H A B B A R

I .

R A N A P U R W A L A ,

M P H

IN THE PAST 20 YEARS, DIVE INJURIES AND FATALITIES DECLINED even as participation in scuba diving increased. This decline can be attributed to better training, equipment, research and access to health care. With the increase in participation there exists a need for continued improvement in diver safety. DAN’s research is an important part of the effort to enhance divers’ understanding of the risks, promote better protocols and raise safety awareness in the dive community.

BACKGROUND

Checklists are proven tools in high-risk disciplines such as aviation and surgery.

Increased use of checklists by divers may promote a reduction in injuries and fatalities.

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We know the most common causes of dive fatalities are drowning, arterial gas embolism and cardiac incidents. The majority of these deaths are labeled drowning, but most experts believe that drowning is usually preceded by other debilitating injuries. In 2008 a DAN study investigated 947 diving deaths and suggested a common chain of events in these deaths: the triggering event, the disabling agent, the disabling injury and the cause of death.

In an earlier study, researchers used a similar approach to review all work-related deaths in Australia that occurred from 1982 to 1984, identifying precursor events and contributing factors.

Both these studies concluded that prevention strategies aimed at reducing triggers and precursor events could reduce injuries and fatalities.

It is not easy to look back at accidents and establish their root causes, but this approach allowed the authors of both studies to conclude most accidents are caused by preventable mishaps — unplanned and unwanted events that increase the risk of injury. The mishaps identified in both studies could be categorized as human errors, equipment problems or environmental factors. The most common diving mishaps are out-of-air scenarios, rapid ascents,

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equipment problems and entrapment. Reducing mishaps, especially human errors and equipment problems, seems to be the key to decreasing injuries and fatalities.

CHECKLISTS One way to reduce mishaps is to remember important safety procedures and follow them. Avoiding, omitting, neglecting or failing to understand the importance of such procedures leads to human errors. These errors can compound with increasing stress, difficult-to-operate or malfunctioning equipment and environmental challenges.

A checklist is a handy tool for reducing errors, improving performance and meeting safety standards.

OUTSIDE OF DIVING Checklists have proven effective in high-risk disciplines including aviation and surgery. In aviation, their use is well enforced. Pilots and crews of military and commercial aircraft all have checklists for various procedures they must adhere to; completion and submission is required.

The World Health Organization (WHO) has promoted surgical checklists during the past four years. They have been found to reduce deaths and complications by streamlining communication among surgical teams and hospital staff.

The benefits of using checklists have also been demonstrated in recreational settings. A program called “Bikes, Blades and Boards,” conducted at Hamilton Health Sciences in Hamilton, Ontario, judged children’s performance wearing helmets using a helmet checklist and addressed mishaps related to fit, adjustment and condition of helmets. Children who participated in the program and used the checklist scored better in helmet use than children who did not. The experimental group retained the helmet-using skills even a year after the intervention.

IN DIVING Standard predive procedures include a review of equipment, the dive plan and responses to unplanned events. We hypothesize that the use of a predive checklist reinforces these steps and reduces mishaps related to human error and equipment problems. Such reinforcement may be especially important in recreational diving because of the significant intervals between dives (months or even years) for many recreational divers.

Checklists have a long history in diving. U.S. Navy divers employ a thorough predive checklist before dives, and compliance is strictly regulated. The Professional Association of Diving Instructors (PADI) uses the acronym “BWRAF” when teaching predive checks to recreational divers. The acronym stands for BCD, Weights, Releases, Air and Final OK. Many mnemonics are used, including the well-known “Begin With Review

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And Friend” and a colorful variety of others. The National Association of Underwater Instructors (NAUI) diving manual features various checklists including one that uses the acronym “SEA BAG.” The safety topics referenced by this acronym are Site survey, Emergency, Activity, Buoyancy, Air, and Gear and go. The intent of this “on-site” checklist is similar to that of a predive checklist, but it provides a general review of safety considerations rather than a step-by-step list of tasks to complete. The American Academy of Underwater Sciences (AAUS) also advises divers to conduct a predive check and provides a format in its manual.

Divers are trained to conduct predive safety checks and may acknowledge the benefits checklists offer, but compliance is questionable. The extent to which any of these checklists are actually used is unknown, and no formal evaluations of their efficacy have been conducted.

EVALUATION OF A PREDIVE CHECKLIST There is no gold standard of predive checklists. With input from dive-medicine researchers, dive instructors, physicians trained in dive medicine and diver medical technicians (DMTs), DAN developed a predive checklist for evaluation. It was pretested on 16 divers in a field setting to ensure clarity of content, assess the effort involved in completion and determine the acceptability of the checklist to divers.

To evaluate the checklist’s effectiveness, DAN conducted an intervention trial in the summer of 2012.

The intervention groups of divers used DAN’s predive checklist, while the control group did not. At the end of each dive day, researchers asked all divers to complete a questionnaire about diving mishaps. The data were collected and are currently being analyzed; the incidence of mishaps between the two groups will be compared.

Extreme depth-time profiles and running low on air are known to increase divers’ risk of injury. To address these variables, researchers included a dive plan in the intervention: Participants were asked to plan the depth of their dive and to estimate their breathing-gas needs at different stages of the dive. Additionally, the intervention tool included four safety tips and a postdive log for divers to record actual dive parameters.

If the checklist promotes closer adherence to safety guidelines as we hypothesize, the primary benefit will be a decrease in mishaps related to equipment and human error and a consequent reduction in the incidence of injuries.

Additional benefits from a public health perspective may include a decrease in the financial burden of treatment costs, a reduction in lost productive time due to injury, disability or death, and safer, more enjoyable experiences for divers. The checklist and the results from the intervention trials will be made public once the analysis is complete. AD DAN.ORG

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IMMERSION PULMONARY EDEMA B Y

B R I A N

H A R P E R

PULMONARY EDEMA IS AN ABNORMAL LEAKAGE of fluid from the bloodstream into the alveoli, the microscopic air sacs in the lungs. It is most often the result of heart failure or other cardiac problems. Sometimes, however, pulmonary edema is observed in swimmers and divers when no underlying medical cause is apparent. This condition, immersion pulmonary edema (IPE), presents as a rapid onset of shortness of breath, cough and sometimes bloodtinged, frothy sputum. Because the fluid builds up in the air-containing spaces of the lungs and interrupts gas exchange, IPE resembles drowning. The important difference is that the obstructing fluid comes from within the body rather than from inhalation of surrounding water.

DAN Medical Services receives a few calls each month in which divers report symptoms suggestive of IPE. Anyone who experiences sudden shortness of breath or persistent cough while diving should abort the dive in as safe a manner as possible and breathe 100 percent oxygen on the surface. Further diving should be postponed until a physician can be consulted. Although IPE often resolves quickly once a diver has exited the water, respiratory distress in the diving environment can be extremely dangerous.

Why does IPE occur?

Douglas Ebersole: IPE is an uncommon condition first reported in 1989. It was originally described in cold-water diving and called “cold-induced pulmonary edema,” but it has now been reported in warm-water diving as well. An absence of chest pain helps differentiate IPE from pulmonary decompression sickness (“chokes”). The exact mechanism is not known, but it is thought to be due to a combination of the increased hydrostatic pressure in the pulmonary 98 |

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capillaries that occurs with immersion in water and the presence of a gradient between the hydrostatic pressure at mouth level and at chest level when a diver is upright.

Additionally, diving causes increased negative pressure in the alveoli due to denser breathing gas and when using a poorly tuned regulator.

Immersion in water causes a number of physiologic effects including a rapid distribution of blood from the legs to the thorax, which can increase blood volume in the thorax by up to 700 ml. This additional blood causes an increase in pressure in the right atrium by 16-18 mm Hg, a 30-percent increase in cardiac output and a slight increase in blood pressure. Divers with conditions such as hypertension or underlying cardiovascular disease, especially those with weakened heart muscle function, are less able to tolerate these physiologic changes and are thus more prone to pulmonary edema. No large studies have been performed, but review of the medical literature shows several small case studies of patients with IPE. In these, a high percentage of subjects had hypertension or cardiovascular disease. Most of them also report a higher proportion of women.

Alfred Bove: There are several scenarios that provoke IPE. High-intensity surface swimming causes it; this has been reported in triathletes and U.S. Navy SEALs. Divers get IPE when swimming on the bottom without clear evidence of stress. In some cases, the diver relates a tight-breathing regulator, and in others no evident stress or equipment problems are noted. In most cases, cardiac evaluation is normal. Reduced diastolic relaxation (usually a result of long-standing hypertension) can lead to increased venous pressure in the lungs — the usual cause of pulmonary edema from cardiac problems. Measurements of both systolic and diastolic heart function can be readily obtained from an echocardiogram. IPE is not a manifestation of decompression sickness and does not require recompression. The treatment is oxygen and diuretics to remove water from the lungs.

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to be shunted to the core. Yet again, one would think this volume would not be enough to overwhelm a young, healthy circulatory system. None of these theories explains why IPE may occur in an individual during a particular dive while other divers diving the same profile and wearing the same thermal protection remain unaffected.

Yet another theory suggests IPE is the result of respiratory mechanics. This idea is that a strong, forced inhalation against resistance (essentially overbreathing a snorkel or regulator) may cause the lungs to respond by leaking fluid out of the capillaries and into the alveoli (pulmonary edema). This may explain why young, healthy swimmers with strong lungs may develop IPE especially during particularly strenuous swims. There may also be a genetic component to IPE. In other words, some individuals may have the potential to develop IPE under certain conditions, yet others may never develop IPE even under the same stress. Though there may be a genetic predisposition, I have seen and treated cases of IPE and then returned the diver to full duty with no recurrence.

The diver went on to complete identical dive profiles, wearing the same thermal protection and breathing the same regulator, but never again developed IPE. Of course, it may be that the circumstances of the subsequent dives never matched identically the IPE trigger (or triggers) of the culprit dive.

Under what circumstances can someone who experienced IPE return to diving?

Bove: One common problem is excess hydration coupled with rapid onset of heavy swimming exercise on the surface. In triathletes who develop IPE, excess hydration and rapid onset of extreme exercise while immersed should be avoided. Military divers are instructed to avoid overhydration before high-energy swimming. Divers are advised to ensure normal regulator function and not

STEPHEN FRINK

Pete Witucki: We don’t know, and this is the dilemma. There have been multiple proposed theories, but none seems completely satisfactory.

One theory suggests that prolonged immersion in cold water causes peripheral blood vessels to constrict and shunt blood to the heart and central circulation, which then leads to fluid leaking into the lungs. However, one would think that otherwise healthy individuals should be able to compensate for this fluid shift. Not to mention, IPE has been documented to occur in warm water. Another theory, similar to the first, is that hydrostatic pressure from the water causes blood DAN.ORG

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to use regulators that allow breathing resistance to be increased. The majority of divers can return to diving with proper precautions and confirmation their cardiac evaluation is normal.

Ebersole: Unfortunately, very little is known about the likelihood of recurrent IPE once a diver has had an episode. After an episode of IPE, there is often spontaneous recovery once the diver leaves the water. If not, it tends to respond to standard therapy for pulmonary edema, such as diuretics. Whether or not a diver should return to diving after an episode of IPE should be determined on a case-by-case basis. The decision should be based on the physical condition of the diver, a history of hypertension or cardiovascular disease and the type of diving being considered. Obviously, shallow warm-water diving in a young, healthy diver who suffered a mild case of IPE is less concerning than a middle-aged diver with multiple medical problems who wants to return to cold-water diving after a severe episode of IPE that required hospitalization.

Witucki: An otherwise healthy person who has experienced a single, isolated episode of IPE may return to diving once all symptoms have resolved. This person should be counseled that futures dives should be aborted if they again develop signs of IPE. Again, I have treated many cases and subsequently returned these divers to full duty without recurrence. A person who has known or potential cardiac disease (hypertension, advanced age, diabetes) and develops IPE is a different matter. These people should have further cardiac evaluation prior to diving to make sure they do not have heart valve problems or underlying blockages in their coronary arteries. The results of this further testing should dictate return to diving. A person who experiences recurrent episodes of IPE should probably refrain from diving again in the future.

What do we not understand about IPE — in what ways is it still a mystery?

Bove: The mechanisms of IPE are not well understood.

The phenomenon of negative-pressure pulmonary edema is well known in anesthesia and likely contributes to IPE in divers. The development of pulmonary edema in swimmers is better understood and has a model in the well-known pulmonary edema problem found in highly motivated racehorses. However, there are still a number of divers and swimmers who get IPE who don’t have a good explanation for why it occurred.

Ebersole: Despite the best efforts of many investigators, the medical community does not know much about IPE. Until we better understand the mechanism of the disorder 100 |

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MEET THE EXPERTS Alfred Bove, M.D., Ph.D., is professor emeritus of medicine at the Temple University School of Medicine in Philadelphia, Pa. He is board certified in cardiology, internal medicine, and undersea and hyperbaric medicine. Dr. Bove is a National Association of Underwater Instructors (NAUI) lifetime scuba instructor, course director for Temple University Underwater Medicine and author of the textbook Diving Medicine.

Douglas Ebersole, M.D., is an invasive and interventional cardiologist at Watson Clinic and director of the cardiac catheterization laboratories at Lakeland Regional Medical Center in Lakeland, Fla. He is a cave and technical diver, a Scuba Schools International (SSI) instructor and an International Association of Nitrox and Technical Divers (IANTD) and Technical Diving International (TDI) rebreather and trimix instructor.

Pete Witucki, M.D., is a faculty member in the Department of Emergency Medicine at University of California San Diego Medical Center. He is board certified in emergency medicine as well as undersea and hyperbaric medicine. He served as a Diving Medical Officer (DMO) in the U.S. Navy for four years and continues to serve as a DMO in the U.S. Navy Reserves.

and who is predisposed to it, it is difficult to make recommendations to divers as to how to avoid it or when to return to diving after an episode.

Witucki: The cause! We do not know what causes IPE nor can we currently predict which people are at increased risk of developing this condition. We know how to identify and treat IPE. We know the disease involves fluid leaking out of pulmonary capillaries and into the alveoli. What we do not know is why it occurs. It is hoped the research that is currently under way will answer this question or at least begin to lead us in the right direction. AD

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