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diabetes, malnutrition, poor tissue perfusion, the use of steroids or other immunosuppressant drugs, a preoperative stay in a hospital (more than four days), colonization with Staphylococcus aureus or remote infection at the time of surgery.5 Additional factors include radiation therapy to the surgical site, blood transfusion (causes reduced macrophage activity) and previous history of SSI.3,5 Diabetic patients with poor blood glucose control are at significant risk for postoperative infection. Patients with a preoperative blood glucose level of 200 mg/dL or more have a greater risk of SSI. Hyperglycemia results in impaired host defenses by impairing polymorphonuclear leukocyte functions, including adherence, chemotaxis, phagocytosis and bactericidal activity. In a study of cardiothoracic patients, hyperglycemia was associated with a 102% increase in the risk for wound infection.3 It appears that the risk of infection increases fourfold if the patient becomes hyperglycemic at any time on the first postop day.3 Patients’ blood A1C levels should be maintained below 7%.3 Hospitals should have a standardized glucose management protocol for all patients undergoing surgery. Procedural techniques can influence the risk for infection, such as using the electrocautery on the skin. Residual “dead space” in the wound after closure can lead to infection by creating favorable living conditions for bacteria to multiply. Some surgeons use a wound edge protector drape or an adhesive incise sheet over the exposed skin before the incision is made as a preventive measure. The incise sheets can be plain clear plastic or impregnated with iodophor. A common practice is to irrigate the surgical site with sterile saline or antibiotic solution WWW.ORTODAY.COM
before closing the skin.5 Environmental considerations include adequate surface cleaning with EPA-approved disinfectants and minimizing dissemination of particulates in the air. Surfaces such as push plates, cabinet handles and knobs/buttons/keyboards can harbor harmful bacteria and endospores, such as clostridia (e.g., Clostridium difficile). ORs have specialized air-handling systems that exert positive pressure when the door is opened and negative pressure in the corridors. This prevents additional particulate matter from being pulled into the room from the hallway if the door is opened.5 Some specialty rooms have a system of laminar airflow that directs the cleanest air possible toward the sterile field. Some entryways have ultraviolet light for additional bacteriostatic protection. The air quality is maintained at the cleanest levels possible, but air itself is never sterile.5 Human factors in bacterial spread include the attire of the OR staff: sterile gowns and gloves, hair covers that completely cover the hair and ears, and masks. Skull caps should be avoided because the hair at the nape of the neck protrudes and can shed bacteria and particulate into the surgical site.5 The amount of bacteria in the incision at the end of surgery is the major determinant of SSIs. More than 40 years ago, the CDC used a clinical estimate of the amount of bacteria likely to be encountered in the surgical site during surgery to develop a surgical wound classification system. Four classes of surgical procedures were determined: clean, cleancontaminated, contaminated and dirty or infected — each with a distinctive infection risk rate:5 • Class 1: Clean procedures: an
uninfected primary surgical incision without inflammation; respiratory, GI, biliary or genitourinary tracts not entered; 1% to 2% infection rate without prophylactic antibiotics. Closed by primary intention and may be drained with closed-system drainage. May be a nonpenetrating blunt trauma injury opened for exploration in the OR. No break in sterile technique • Class 2: Clean-contaminated procedures: surgical incisions in which respiratory, GI, biliary and genitourinary tract are entered under controlled conditions with minimal spillage and no encounter with infected urine or bile; 6% to 9% infection rate without prophylactic antibiotics. No break in sterile technique • Class 3: Contaminated procedures: open, fresh, accidental wounds (of less than four hours duration) and surgeries with major breaks in sterile technique (e.g., open cardiac massage) or gross spillage from the GI tract; also includes incisions in which acute, nonpurulent inflammation is encountered; 13% to 20% infection rate without prophylactic antibiotics • Class 4: Dirty/infected procedures: purulent inflammation present. Includes old traumatic wounds (of more than four hours duration) with retained dead tissues and those that involve existing clinical infection or perforated viscera; about 40% infection rate without prophylactic antibiotics Surgical risk is further defined by three additional risk factors that play a significant role in wound infections: an operation lasting more than two hours, one involving the abdomen or one performed on a patient having three or more underlying diagnoses (indicative of July/August 2016 | OR TODAY
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