THE EFFICACY OF LIPOSOMAL BUPIVICAINE IN REGIONAL NERVE BLOCKS FOR BELOW KNEE AMPUTATIONS: A RETROSPECTIVE CASE-CONTROLLED STUDY

Objectives: Postamputation pain is highly prevalent with an incidence of up to 95%. The pathophysiology of amputation pain is multifactorial therefore the emphasis for a multimodal pain regimen is essential. Opioids are utilized in the postoperative course; however, their side effect profile can prolong a patient’s hospital stay. The field of regional anesthesia has grown to provide new techniques for amputations for better pain control. In addition, liposomal bupivacaine (LB) was introduced as a means to extend a nerve block from hours into days. Regional nerve blocks with liposomal bupivacaine for below knee amputation (BKA) procedures can have the potential to reduce opioid use after surgery.

Methods: A retrospective, case-controlled chart review was conducted for patients who had received LB regional nerve blocks vs. patients who did not receive a regional nerve block for post-operative pain control in BKAs. Charts were reviewed for the years 2019-2021 at a single academic institution. The primary outcome was postoperative opioid requirements in oral morphine equivalents (OME). The secondary outcome was hospital length of stay. Daily average opioid consumption was evaluated from the time in postoperative acute care unit (PACU) until day of discharge. The PO/IV opioids used per patient during this time period was converted to OME equivalents to standardize opioid use across both study groups.

Results: A total of 69 patients who underwent below knee amputations (32 LB vs. 37 control) were reviewed between 2019-2021. Mean OME was lower in the LB group compared to control group (331.5 vs. 859.5 OME, respectively; p=0.002). A higher percentage of patients in the study group were categorized in the 0-40 OME range (minimal opioid use after surgery) when compared to the control group. More patients in the control group had OME use > 61, which falls under severe or excessive opioid usage. There was no difference detected between average length of stay between the two groups.

Conclusion: Liposomal Bupivacaine regional nerve blocks for the BKA population are considered a relatively novel approach in pain control. There have been few studies/case reports detailing its usage so far. Our exploratory study shows that patients who received LB nerve blocks had significantly lower opioid consumption compared to patients who did not receive LB. The use of LB in regional nerve blocks may reduce opioid consumption for below knee amputation procedures.