Factors Affecting Perioperative Mortality and Wound Related Complications Following Major Lower Extremity Amputations

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Patrick A. Stone, MD¹, Sarah K. Flaherty, BS², J. David Hayes, MD¹, Stephen M. Hass, MD¹, J. Michelle Jackson, DO¹, Matthew J. Hofeldt, MD¹, Casey S. Hager, MD¹, Michael Elmore, MD¹, Ali F. AbuRahma, MD¹.
¹West Virginia University School of Medicine - Charleston Division, Charleston, WV, USA, ²Charleston Area Medical Center Health Education and Research Institute, Charleston, WV, USA.

BACKGROUND:
Major lower extremity amputations continue to be associated with significant morbidity and mortality, however no recent large series has evaluated factors associated with perioperative mortality and wound complications. The purpose of this study is to examine the association of patient comorbidites, operative indications and perioperative factors with perioperative morbidity and mortality in vascular patients undergoing lower extremity amputations at a tertiary care center, serving a predominantly rural patient population.
METHODS:
A retrospective review was conducted of all adult patients who underwent non-traumatic major lower extremity amputation of the forefoot and proximal over a 5-year period at a single tertiary care center that serves a predominantly rural patient population. Demographic data, pre-existing medical conditions, indications for surgery, perioperative data and outcomes were collected and analyzed to identify their relationship with perioperative mortality (within 30 days of surgery), as well as wound infection and early revisions (within 90 days) to a more proximal level. Variables were examined using chi-square, two-tailed t-test, and a logistic regression model.
RESULTS:
Four hundred and eleven patients (62% male) underwent 508 major lower extremity amputations from 1999-2003. The initial level of amputation included 61 transmetatarsal (TMA), 252 below knee (BKA), 193 above knee (AKA) and 2 hip disarticulations. Overall early wound complications (wound infections & revisions) were noted in 19% (N=78) and perioperative mortality was 16% (N=67). An age greater than 70 years (P=0.02), a history of chronic obstructive pulmonary disease (with home oxygen requirements, P=0.03), previous total hip arthroplasty (P=0.03), renal failure requiring hemodialysis (P=0.03), and an albumin of 2 g/dL or less (P<0.0001) were significantly associated with perioperative mortality. Amputation following acute limb ischemia was also associated with increased perioperative mortality (P=0.02) compared to those with infectious indications or chronic limb ischemia. History of previous coronary artery bypass grafting (CABG) had a protective effect (P=0.007). From the regression model, age, albumin level and lack of a previous CABG were found to be independently related to mortality. Patients who did not have a previous CABG were nearly 4 times more likely to die than those who did (P=0.002). An operative temperature below 36°C, a preoperative albumin less than or equal to 2 g/dL, and a peak perioperative glucose greater than 200 mg/dL, were not found to be significantly associated with poor wound healing.
CONCLUSIONS:
Major lower extremity amputation in patients with peripheral vascular disease continues to be associated with considerable perioperative morbidity and mortality. Previous coronary bypass has a protective effect. Multiple comorbidities are associated with increased perioperative mortality. Wound complications do not appear to be significantly affected by comorbidities and most likely stem from more proximal local tissue ischemia.