Improving Outcomes for Lower Extremity Amputations Using Intraoperative Fluorescent Angiography to Predict Flap Viability

Abstract

Objectives: Nearly 25% of vascular surgery patients operated on for peripheral vascular disease are readmitted within 30 days. Development of adjuncts to minimize wound complications remains an area of great interest. Here, we present our experience with intraoperative fluorescent angiography (IFA) as a tool to predict skin flap viability following lower extremity amputations (LEAs). Methods: Experience with IFA using indocyanine green (ICG) dye was reviewed retrospectively at a single institution. Records of patients undergoing LEA with use of IFA by 2 vascular surgeons from 2013 to 2014 were reviewed. Absolute and relative tissue perfusion values were evaluated for sensitivity and specificity in regard to skin flap viability. Results: Thirteen patients with a mean age of 70.5 years (standard deviation [SD] = 12.0, range: 49-93 years) underwent 17 amputations. Indications included rest pain, tissue gangrene, and vascular disease unsuitable for revascularization. Amputation levels included toe (23%), transmetatarsal (18%), below knee (41%), and above knee (18%). Six (35%) amputations required revision with a mean time-to-revision of 26.1 days (SD = 19.9, range: 9-61 days). Of these revisions, 14 (83%) patients proceeded to a proximal-level amputation. Mean follow-up was 235 days (SD = 148, range: 5-448 days), and IFA was used in all cases. Absolute perfusion values (APVs) between 5 and 9 displayed sensitivity and specificity of 50% and 64%, respectively. Additionally, a relative perfusion value (RPV) of ≤31% displayed 100% sensitivity and specificity. Sensitivity and specificity fell to 83% at a relative perfusion of ≤27% and ≤35%, respectively. Conclusion: IFA during LEA is safe and easily performed by the vascular surgeon. The RPVs as a predictor of skin flap viability correlate well with those reported in breast reconstructive surgery. Unfortunately, APVs fail to support any predication for flap failure or success. Patient comorbidities and intraoperative variables such as vasopressor use may contribute to this finding.