Necrotizing soft tissue infections of the extremities and back.

Necrotizing soft tissue infections are potentially fatal infections that often involve extremities. Studies of mixed anatomic sites suggest several factors increase mortality (eg, age, medical comorbidities, laboratory values, treatment timing). We hypothesized that patients with necrotizing soft tissue infections of the extremities would have similar factors associated with mortality. We retrospectively reviewed 150 patients with necrotizing soft tissue infections of the extremities treated at San Francisco General Hospital from 1993-1997. We recorded cofactors, treatment, physical findings, radio- graphs, and laboratory findings at presentation. No cofactor or examination finding was associated with increased mortality. Compared with survivors, nonsurvivors had a higher leukocyte count, blood urea nitrogen, creatinine, potassium, partial thromboplastin time, and aspartate aminotransferase, but had lower pH and bicarbonate. Nonsurvivors did not have delays in treatment relative to survivors. Univariate analysis showed an increased risk of mortality in patients with hypotension, hypothermia, Clostridium species in the wound culture, low leukocyte count and bicarbonate levels, and elevated blood urea nitrogen, aspartate aminotransferase, creatinine, and potassium levels. Several signs of shock and organ dysfunction were associated with mortality in patients with necrotizing soft tissue infections of the extremities. The overall mortality rate (9.3%) was lower than in some other reports.