Preventing Surgical Site Infections

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Antimicrobial prophylaxis after wound closure is unnecessary; published evidence demonstrates the non-inferiority of single dose prophylaxis when compared with multiple dose prophylaxis (5). Further, prolonged use of antimicrobial prophylaxis is associated with the emergence of resistant organisms (6-8). By ensuring that the duration of prophylaxis does not exceed 24 hours past the end of the operation, hospitalists can make valuable contributions to public health and cost containment.

Non-Antimicrobial Measures

Several non-antimicrobial measures also significantly reduce SSI rates. Those that fall outside the domain of the hospitalist and into the direct purview of the operative team include high levels of inspired oxygen, maintenance of perioperative normothermia, and use of clippers rather than a razor when hair removal is necessary. The risk of SSIs is directly related to tissue oxygenation. Bacterial infectivity is enhanced and cellular immunity is compromised in hypoperfused, poorly oxygenated tissue (9). The practice of administering perioperative supplemental oxygen (at least 80% FIO2 in intubated patients) reduces the risk of SSI by nearly one-half (1). For non-intubated patients, oxygen at 12 L/min by non-rebreathing face mask applied intra-operatively and for at least 2 hours following surgery leads to similar reductions of SSI rates. Besides being effective, this intervention is inexpensive, has no recognized adverse effects, and carries the added benefit of significantly reducing post-operative nausea and vomiting (4).

Hypothermia also predisposes the surgical wound to infection. Even mild perioperative hypothermia (i.e., core temperature 35-36.5°C) typically occurs in the absence of specific measures to prevent net heat loss. Perioperative hypothermia is the combined result of exposure and anesthetic-induced thermo-dysregulation, with redistribution of core body heat to the periphery (4). Even mild hypothermia causes vasoconstriction which diminishes perfusion, dropping tissue oxygen tension which impairs phagocytosis and oxidative killing by neutrophils (10). Hypothermia also blunts scar formation which further diminishes wound integrity. Active warming of the patient to maintain a core temperature near 36.5°C constitutes the intra-operative standard of care and is effective at reducing the risk of SSIs by as much as two-thirds (1).

Hyperglycemia, an established independent risk factor for an array of adverse outcomes in hospitalized patients, is also an independent risk factor for SSIs across a range of surgical patients (1). Short-term hyperglycemia depresses immune function through nonenzymatic glycosylation of immunoglobulin and by impairing normal leukocyte performance (11). Among diabetic cardiac surgery patients, reduction of hyperglycemia with an intravenous insulin infusion lowered the incidence of deep sternal wound infection by as much as two-thirds (12). While the value of achieving glycemic targets has already been established for a variety of important endpoints and across a range of inpatient populations, hospitalists should stay tuned. As high quality studies emerge proving that glycemic control lowers SSIs among non-cardiac surgical subpopulations, hospitalists may increasingly be relied upon to achieve strict glycemic targets.

By recognizing and coordinating practices known to reduce SSIs, hospitalists can elevate the level of care provided for surgical patients. At the same time, hospitalists can help lower costs and keep the hospital system mindful of public health goals, such as prevention of antimicrobial resistance. While individual hospitalists have key roles to play, the overall approach to SSI reduction calls for a coordinated, multidisciplinary team approach with process and system-level efforts.

Dr. Stein can be contacted at [email protected].

References

1. Auerbach AD. Prevention of surgical site infections. In: Shojania KG, Duncan BW, McDonald KM, et al., eds. Making health care safer: a critical analysis of patient safety practices. Evidence report/technology assessment no. 43. AHRQ publication no. 01-E058. Rockville, MD: Agency for Healthcare Research and Quality, 20 July 2001:221-44.
2. Kirkland KB, Briggs JP, Trivette SL, Wilkinson WE, Sexton DJ. The impact of surgical site infections in the 1990s: attributable mortality, excess length of hospitalization, and extra costs. Infect Control Hosp Epidemiol. 1999;20:725-30.
3. National Nosocomial Infections Surveillance (NNIS) report, data summary from October 1986-April 1996, issued May 1996: a report from the National Nosocomial Infections Surveillance (NNIS) system. Am J Infect Control. 1996;24:380-8.
4. Sessler DI, Akca O. Nonpharmacologic prevention of surgical wound infections. Clin Infect Dis. 2002;35:1397 404.
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9. Hopf HW, Hunt TK, West JM, et al. Wound tissue oxygen tension predicts the risk of wound infection in surgical patients. Arch Surg. 1997;132:997-1005.
10. Kurz A, Sessler DI, Lenhardt RA. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. N Engl J Med. 1996;334:1209-15.
11. Garber AJ, Moghissi ES, Bransome ED Jr, et al. American College of Endocrinology Task Force on Inpatient Diabetes Metabolic Control. American College of Endocrinology position statement on inpatient diabetes and metabolic control. Endocr Pract. 2004;Mar-Apr;10Suppl2:4-9.
12. Furnary AP, Zerr K, Grunkemeier GL, Starr A. Continuous intravenous insulin infusion reduces the incidence of deep sternal wound infection in diabetic patients after cardiac surgical procedures [with discussion]. Ann Thorac Surg. 1999;67:352-62.