Peripheral Nerve Blocks as a Primary Anesthetic for Above-the-Knee Amputations: A Prospective Feasibility Study

Above-the-knee amputation is a commonly performed surgical procedure that is associated with significant morbidity and mortality. It is unknown if these operations can be reliably performed using peripheral nerve blocks and deep sedation instead of general anesthesia, nor is it known whether anesthetic type influences perioperative mortality.

In this prospective proof-of-concept controlled study, 29 patients scheduled for above-the-knee amputations at a single Veterans Health Administration hospital underwent preoperative placement of femoral and sciatic nerve catheters as well as single-injection obturator and lateral femoral cutaneous nerve blocks, followed by administration of deep sedation for their operation.

Block success, intraoperative and postoperative analgesic administration, and conversions to general anesthesia were recorded. Postanesthesia care unit pain scores, patient satisfaction, and mortality at 30 days as well as at the time of study conclusion were assessed. Twenty-nine patients underwent 30 above-the-knee amputations during the study period. The mean age was 69.9 years and 100% were male. One patient required conversion to general anesthesia. Ninety percent (n = 27) of patients reported zero pain upon postanesthesia care unit arrival, and 96.7% (n = 29) were "extremely satisfied" or "satisfied" with their anesthetic care. One patient died within 30 days postoperatively and only 13 patients were alive at study conclusion (median follow-up: 48 months).

Our findings suggest that peripheral nerve blocks with deep sedation may offer a reliable and feasible anesthetic option, particularly for high-risk patients. Further research is needed to determine the impact of anesthetic type on outcomes.