Predictors of poor outcome in infrainguinal bypass for trauma

Abstract

Background: Trauma remains a leading cause of morbidity and mortality worldwide. Vascular injuries are present in approximately 1% to 2% of trauma patients, with the majority of injuries occurring to the extremities. Trauma patients with vascular injuries have been shown to have increased morbidity and mortality as well as the need for increased resources compared with those without vascular injuries. This study aimed to determine predictors of poor outcomes in infrainguinal bypasses performed for traumatic arterial injury.

Methods: All patients admitted between September 1999 and July 2015 who underwent infrainguinal arterial bypass for trauma at a single level I trauma center were included for analysis. The primary outcome was a composite of thrombosis leading to graft abandonment, revision, amputation, or death. Data were analyzed by univariate descriptive and multiple logistic regression analyses. Long-term data were analyzed by Kaplan-Meier method.

Results: During the study period, 108 patients presented with and underwent infrainguinal arterial bypass for traumatic arterial injury. The cohort had a mean age of 35.8 years (16/108 female [15%]). The average Injury Severity Score was 15.2; admission glomerular filtration rate, 79.3 mL/min/1.73 m²; Mangled Extremity Severity Score (MESS), 6; and injury to operating room time, 5.1 hours. Of 108 patients, 37 (34%) had penetrating injury, 71 (66%) had blunt injury, 10 (9.3%) had diabetes mellitus, and 76 (70.4%) had a below-knee target for bypass. Univariate risk factors for poor outcome included age >40 years (odds ratio [OR], 3.27 [1.40-7.65]; P < .01), MESS ≥7 (OR, 5.19 [2.08-19.97]; P < .01), blunt mechanism (OR, 3.35 [1.24-9.07]; P = .02), popliteal artery injury (OR, 3.04 [1.22-7.6]; P = .02), and below-knee target vessel (OR, 4.32 [1.37-13.58]; P = .01). Concomitant orthopedic injuries (P = .08) were not associated with poor outcome. Baseline renal function, type of repair performed (end-to-side vs interposition bypass), injury to surgery time, surgeon's specialty, and associated venous injuries were not significantly predictive of poor outcome. MESS was strongly predictive of poor outcome, with probability rising as high as 95% when MESS reached 12. A score ≥7 (high MESS) was 73% sensitive and 70% specific to predict poor outcomes. Age (OR, 1.03/y; P < .05) and MESS ≥7 (OR, 3.6; P < .03) were persistent predictors of poor outcome in multivariable analysis.

Conclusions: Poor outcomes in infrainguinal bypass for trauma are significantly predicted by the MESS, with poor outcomes occurring >50% of the time when MESS is ≥9 and >75% of the time when MESS is ≥11. Whereas amputation vs revascularization is a decision that also depends on nerve and soft tissue damage and other comorbidities, the MESS helps frame the data for the clinician and can aid in decision-making. Patients and family should understand that poor outcomes are more likely when MESS is ≥9. For patients with MESS ≥11, primary amputation can be considered.

Keywords: Infrainguinal bypass; Mangled Extremity Severity Score (MESS); Traumatic arterial injury.