Issue 124 parenteral nutrition a dietitians role

COVER STORY

PARENTERAL NUTRITION: A DIETITIAN’S ROLE Bernadette Tavner Allsopp, Advanced Dietitian, Acute Team Lead Stoke Mandeville Hospital

Bernadette qualified as a dietitian in 1990.

She works as an Advanced Dietitian in Nutrition Support.

She has also worked in: Saudi Arabia, County Durham, an NGO in Sri Lanka and Kent.

For full article references please email info@ networkhealth group.co.uk

Over the past 13 years as a nutrition support dietitian at Stoke Mandeville Hospital (SMH), part of Buckinghamshire Healthcare NHS Trust, I have had the opportunity to develop and work with a proactive and supportive Nutrition Team.

Approximately 45% of my clinical time is spent in parenteral nutrition (PN) work, completing wardrounds,8 development work, training or collating data for the safe use and provision of total parenteral nutrition (TPN) for the trust. Stoke Mandeville, a district general hospital, is the site for surgical emergency and acute gastroenterology work and hosts the main Intensive Care unit for the Trust.

I work closely with a nutrition and surgical pharmacist in addition to a Lead Nutrition Consultant and Gastroenterologist and Nutrition Nurse Specialist. Our team is also supported by a General Colorectal Surgeon and other members of the multidisciplinary team (MDT), such as the Out-patient Parenteral Antimicrobial Therapy (OPAT) Clinical Nurse Specialist Team.

Effective Nutrition Teams are vital to ensure the appropriate use of and safe provision of PN in a hospital setting.1 The pharmacist and I complete a Ward-based bedside assessment of patients receiving TPN three times a week (Monday, Wednesday and Friday). As we do not cover weekends, we have found this to be more efficient than daily ward rounds. Although TPN is never an emergency treatment,2 the on-call pharmacist will facilitate the TPN prescription if the requesting Consultant team provide sufficient evidence of need. On Fridays, we are joined by our Consultant and Nutrition Nurse. We generally accept

referrals before 12 midday Monday to Friday, but can be more flexible if we have capacity. Our trust strongly supports interdisciplinary working and, as such, we have close and supportive working relationships with our Anesthetic and Surgical colleagues, enabling joint decisionmaking in complex nutrition cases.

Currently, we stock one type of TPN bag with a three-month expiry which contains: 2,520mls, 10gN, 1,750kcals.

This type of bag is sufficient to meet the initial requirements of our patients.

Results from our audit monitoring suggests two-thirds are likely to be at risk from re-feeding syndrome with a third requiring 50% nutrition requirements initially. All other TPN is out-sourced to a company which make up the ‘Bespoke TPN’ regimens required. This method of provision is required as we have had limited pharmacy storage and no capacity in pharmacy to make additions to bags.

The advantage of using bespoke TPN has been to design regimens to optimise wound healing and nutrition support. However, this has also had a cost implication. The pharmacist and I are working to look at more costeffective ways of providing TPN. TPN ASSESSMENT AND MONITORING

Working in TPN rarely, or for the first time, can appear daunting.

There are some differences from enteral nutrition, but the principles regarding: Dietetic diagnosis, outcomes and goal setting remain the www.NHDmag.com May 2017 - Issue 124

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CLINICAL

same.5 Initial assessment tools (ABCDE) and monitoring/evaluation are used and, overall, most assessment data is similar. In addition, working within a Nutrition Team and/or working with an experienced pharmacist will provide support. However, always work within your competency and manage your caseload safely. If you are lone working, never feel pressured to provide TPN. It may be better to wait until the next working day when more experienced colleagues can support your working.4 TPN is usually initiated over a 24-hour period. The feed time can be reduced to a minimum of 12 hours over several days once the feeding aim has been reached and the patient has achieved glycemic stability.

Initial assessment Anthropometry: weight, weight loss, BMI. Also consider size of wound areas (pressure areas, abdominal wounds).

Biochemistry: i) Biochemical trends including: magnesium, phosphate and corrected calcium, as these can be added to TPN regimens. ii) Blood glucose monitoring. All TPN patients require blood glucose checks, it provides an indicator of sepsis as well as a marker for diabetes. iii) Check electrolyte content of intravenous (IV) fluids.

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Clinical: i) Fluid balance. Bedbound surgical patients can often become fluid overloaded.

Assess losses from; gastric, vomit, wound or drains, stoma, urinary or faecal. ii) Temperature. This will affect stress factor calculations and is an indicator of potential sepsis. iii) Respiratory function and heart function.

Will the TPN fluid volume adversely affect the patient’s function? iv) Medication review, particularly prokinetics, antiemetics, antibiotics and IV fluids.

Dietary: i) Usual eating pattern, changes in eating pattern. ii) Number of days with insufficient intake / Nil By Mouth (NBM). iii) Estimated risk of refeeding syndrome.

Consider your dietetic diagnosis, outcome and goals Estimate requirements: i) Calculate protein and energy requirements. ii) Provide sufficient protein, non-protein calorie:nitrogen (NPC:N) ratio to meet your outcome.

Following your assessment, you will have a substantial amount of information with which to work. However, the most important starter questions need to be:

Approximately 85% of our referrals do commence TPN on assessment.

However, 15% will move to enteral nutrition or oral intake.

• Will this individual benefit from TPN regardless of its risk?

• Is the ‘gut’ working?

Approximately 85% of our referrals do commence TPN on assessment. However, 15% will move to enteral nutrition or oral intake. By proactive working with the referral team, TPN can be saved for the most appropriate cases: reestablishing nutrition via the enteral route faster, decreasing hospital stay and potential infection risk, as well as being more cost effective.

Additional information required prior to starting: • Can the referral team suggest how long TPN will be required?

• Which venous assess is available?

• Is the patient easy to cannulate?

The age of the patient and the current patient length of stay will determine peripheral access tolerance with a ‘20G (gauge)’ flow rate 61ml/min, ‘22G flow rate 36mls/min for adults with small veins or ‘24G’ flow rate 22ml/min for elderly with fragile veins should be tolerated.6 PN planned for three to 10 days may be tolerated peripherally.7 A 5mg glyceryl trinitrate (GTN) patch upstream from the cannula8 can be recommended to reduce the risk of phlebitis. Moving the cannula every 48 hours can further reduce the risk; the high osmolarity of the TPN solution irritates veins. Alternatively, a central line such as a dual lumen peripherally inserted central catheter (PICC line), an internal jugular, subclavian line, or a tunnelled central line (Hickman), may be. requested. Commencing a (Visual Intravenous Phlebitis (VIP) score chart is also essential.

MONITORING AND REVIEWING TPN:

Once you have recommended your TPN regimen, documented in the clinical notes and it has been prescribed by the pharmacist, a review within 48 to 72 hours to assess progress both from a physiological and a compliance point of view is required. The following need to be assessed: • Anthropometrics and wound changes if measured.

• The 3 Bs: i) Blood tests - what are the blood trends including urea and electrolytes (U&Es), liver function tests (LFTs), magnesium, bone profile (calcium, phosphate) and hematology. Is the patient under/over-hydrated? What electrolyte additions have been infused besides the TPN? ii) Blood glucose - are levels within range and measured at least twice daily? If >10mmol/L, investigate cause: diabetes, glucose intolerance, insulin insufficiency, sepsis. Consider involvement by Diabetes Specialist Nurse/Specialist Team for sepsis. iii) Balance - what are the loss trends?

Do the gastric residual volumes (GRVs) suggest enteral nutrition can be recommended? Is there sufficient urine being passed? Has the patient passed flatus or stool? Are medications such as prokinetics, oral Magnesium or antibiotics contributing to large faecal losses, >500mls/d or large stomal losses >1,500mls/d. Stopping metoclopramide or oral magnesium can work wonders in reducing losses from what is perceived as ‘malabsorption’. www.NHDmag.com May 2017 - Issue 124

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CLINICAL Table 1: Parenteral electrolyte requirement in practice (adapted from section 3.11 from Pocket Guide to Clinical Nutrition10)

1-1.5mmol/kg

High losses: GRV, stoma, fistula or faecal can result in high sodium requirements. Remember 0.9%NaCL contains 150mmolNa/L. Continue to add sodium until normal levels achieved.

Potassium

1-1.5mmol/kg

Wound, gastric and faecal losses can deplete body potassium.

A rule of thumb suggests to improve serum K+ by 0.3mmol/l you may require 100mmol K+.

Magnesium

0.1-0.2mmol/kg

Losses again contribute to low body stores particularly in intestinal failure.

Phosphate

10mmol/1000kcals

Low levels are often seen in re-feeding and pancreatitis.

Calcium

0.1-0.15mmol/kg

Minimum content of calcium is usually required.

Other

Zinc, selenium, copper may need to be added to TPN > two week duration.

Manganese monitoring may be required with long-term TPN to reduce risk of toxicity.

Sodium

• Access and VIP chart: Is the VIP ‘0’?

Discuss with nurses and team if VIP >1 and request specialist intervention from an IV/ OPAT Nurse. Is the access still appropriate for the patient?

• Requirements: Does the current TPN meet patient requirements/recommended intake? Should TPN be used exclusively, or can trophic feeding begin?

• TPN regimen: Has the regimen been countersigned by a prescriber? Has the prescriber taken into account TPN volume and electrolytes when prescribing IV fluids?

• Clinical changes: Has anything significantly changed that needs to be taken into account which will affect the regimen being proposed?

In addition to BAPEN3 and NICE11 which provide practice guidance and standards for PN, the PN section within the Pocket Guide to Clinical Nutrition produced by the Parenteral and Enteral Nutrition Group (PENG), a specialist sub group of the British 14

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Dietetic Association,10 is one of the best tools to highlight the essential principles of TPN and ‘learn the ropes’ around the use and monitoring of TPN. WHAT ABOUT BESPOKE/TAILORED REGIMENS?

There are several ways to calculate TPN regimens. Below is one example: 1. Calculate Nitrogen (g) then convert to protein (g). Multiply by 4 giving total protein calories.

2. Calculate desired energy intake.

3. Subtract protein calories from desired calories. This will leave NPC. 4. NPC can then be divided into carbohydrate (glucose calories): fat (lipid calories). The ratio can be divided into a 70:30, 60:40 or 50:50 ratio 5. Lipid has been shown to be immunosuppressive and can lead to cholestasis.11 It is recommended not to exceed 1.5g lipid/ kg. In addition, sick septic patients are recommended a lipid load of 0.8-1g/kg.

Therefore, calculate g lipid/kg and multiply by 9 to give lipid calories.

. . . TPN can be saved for the most appropriate cases: re-establishing nutrition via the enteral route faster, decreasing hospital stay and potential infection risk, as well as being more cost effective.

6. Subtract lipid calories from NPC to give glucose calories.

7. Glucose calories can then be converted to grams by dividing by 3.7. Glucose provision must exceed 125g/d as this is the minimum required for brain and cardiac function. If this method is used it is unlikely you will exceed GOR (glucose oxidation rate). Exceeding GOR will lead to the deposition of fat.

8. Determine electrolytes required.

Generally, the focus is on five main electrolytes (see Table 1).

9. Choose a total fluid volume: a volume of <1,250mls is not recommended as the resulting osmolarity of the solution may be unstable. Volumes of up to 4l-5l can be infused over 12 hours; however, specialist reinforced bags are required because of the danger of the bag splitting and the difficulty in attaching it to the drip stand. Most regimens run with a 2-3l content.

10. Include a vitamin and mineral supplement such as ‘Cernevit’ and ‘Additrace’.

11. NB: a) Non-standard bags must be given via a central line only. Osmolarities which exceed >800mmol/l can cause severe phebitis if infused peripherally. b) Always check your working with an experienced colleague (TPN pharmacist, Aseptic pharmacist or the Out-Source TPN provider) for stability.

AUDITING TPN USAGE

Annually, we receive about 130 referrals for TPN at SMH with our sister hospital, Wycombe Hospital, receiving about 20 referrals. About 10% of patients have TPN for >two weeks with only a handful each year requiring admission to a tertiary centre for home TPN. The careful monitoring of TPN referrals, the provision of TPN and any line sepsis resulting from a TPN line is essential to: a) check we are compliant with guidance from ‘NCEPOD A Mixed Bag (2010)’,12 to achieve an infection rate of <4 infections/1,000 TPN days; b) evaluate cost savings for the Trust and c) determine the importance of the Nutrition Team.

TPN provides a considerable amount of interesting and rewarding work for the dietitian.

The variety of work from designing regimens, proactive MDT working, sharing expertise in training, dealing with complex surgical cases, and managing complex feeding decisions, makes each working week very different.

Despite being in this post for 13 years, longer than any previous position, my TPN clinical work offers regular learning opportunities and a great sense of achievement.

With thanks to : Dr Sue Cullen, Gastroenterologist BHT www.NHDmag.com May 2017 - Issue 124

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