Post-Operative Outcomes of General versus Regional Anesthesia for Lower Extremity Amputation.

Abstract

Introduction/objectives: Despite advances to open and endovascular surgery, lower extremity amputation remains an essential component of vascular surgery. Regional anesthesia with peripheral nerve blocks can help avoid the postoperative morbidity associated with general anesthesia. Despite regional anesthesia as an option for patients, a recent large database study found that up to 90% of cases were still performed under general anesthesia. The aim of our study was to further evaluate if there is a significant difference in surgical outcomes that supports the use of regional over general anesthesia.

Methods: This was a single institution retrospective cohort study of patients who received lower extremity amputations from January 1, 2019 until December 31, 2023. Above- and below-knee amputations were included, and all amputations were performed by vascular surgeons. Patients were divided into three groups based on the anesthesia type they received during the case: general anesthesia, general and regional block, and regional block only. Patient characteristics, preoperative comorbidities, and postoperative outcomes were then studied for each group. Continuous variables were summarized by medians and interquartile ranges (IQRs), while categorical variables were summarized by frequencies and percentages. As there were repeated measures for several patients, GEE (generalized estimating equations) models with anesthesia group as the response were fit to assess differences between anesthesia groups. Multivariable models were fit assuming a binomial distribution, Poisson distribution, or multinomial distribution.

Results: A total of 176 amputations were included in this study of whom 55 (35%) received regional block only, 94 (60%) received general anesthesia and block, and 27 (15%) received only general anesthesia. Above knee amputations were performed in 74 (42%) and below knee amputations were performed in 102 (58%) of patients in the study. The block only group was significantly associated with an older population (p = 0.006) and significantly associated with higher percentages of CHF (p = 0.001), CKD (p = 0.006), and diabetes (p = 0.002). The general only group had higher postoperative morbidity, with significantly higher percentages of PE (p < 0.001), DVT (p < 0.001), pneumonia (p = 0.032), and post-op ventilator use (p < 0.001). The general only group had significantly longer hospital length of stay (p = 0.03) and higher rates of expiration (p = 0.002). On multivariable analysis, receiving general anesthesia only was significantly associated with a 30-day (p=0.009), 60-day (p=0.009), and 1 year mortality (p = 0.006).

Conclusion: Our study demonstrates that the use of general anesthesia for lower extremity amputation has a significant and independent correlation with higher 30-day, 60-day, and 1-year mortality rates. Thus, a continued shift toward regional blocks in patients facing lower extremity amputation is indicated.