Predictors of prosthetic graft infection after infrainguinal bypass.

BACKGROUND: Some patients require major leg amputation after lower-extremity prosthetic bypass for graft occlusion or failure of wound healing, despite a patent graft. Amputation above or below the knee was hypothesized to increase susceptibility to prosthetic graft infection in the ipsilateral extremity.

STUDY DESIGN: All patients undergoing implantation of prosthetic infrainguinal arterial bypass grafts identified from a vascular surgical registry during a 12-year period were reviewed. Patient demographic data, comorbid conditions, and operative details were evaluated as risk factors, with graft infection among the primary outcomes of interest.

RESULTS: Prosthetic graft infection occurred in 25 of 141 (18%) infrainguinal grafts and occurred most frequently after major amputation (41% versus 6%; odds ratio [OR] = 12; 95% CI, 4.1 to 34) or early reoperation after initial grafting (70% versus 16%; OR = 11; 95% CI, 1.9 to 63). Risk was highest after amputation within 4 weeks of bypass (70% versus 32%; OR = 5.0; 95% CI, 1.1 to 23). Graft thrombosis (84% versus 39%; OR = 8.3; 95% CI, 2.7 to 26) and presence of gangrene (52% versus 23%; OR = 3.6; 95% CI, 1.5 to 8.7) also increased infection risk. Independent predictors for development of graft infection were identified by stepwise regression analysis to be amputation (p < 0.001), early reoperation (p = 0.002), and absence of renal failure (p = 0.038) but not gangrene (p = 0.090). Amputations performed within 6 months of the initial bypass operation were more likely to be associated with prosthetic graft infection than those performed later than 6 months (52% versus 17%; OR = 5.3; 95% CI, 1.3 to 22).

CONCLUSIONS: Amputation increases risk of prosthetic graft infection, especially when performed early or after failed revascularization. Consideration should be given to partial or complete removal of a prosthetic graft above the level of the amputation under these conditions.