Local Infiltration Anesthesia with Liposomal Bupivacaine Decreases Postoperative Narcotic Consumption in AIS

Background: Our previous standardized postoperative pain management plan for AIS patients undergoing PSF included the placement of an epidural (EPI) catheter by the spine surgeon prior to fascial closure. The epidural was used for 24 hours, in conjunction with a multi-modal post-operative pain protocol. Local Problem: The 2020 COVID-19 pandemic highlighted the need for our surgical AIS patients and their families to have private rooms/bathrooms. Epidural catheters require arterial line blood pressure monitoring to ensure safety. Unfortunately, the arterial lines could not be utilized in the private rooms due to lack of appropriate monitors, therefore we transitioned away from epidurals. Liposomal bupivacaine (LB) is an encapsulated local anesthetic that has a duration of action up to 72 hours. Specific Aims: This quality initiative (QI) focused on the enhancement of the standardized postoperative care pathway for AIS patients undergoing PSF. The aims of the initiative were to 1) minimize narcotic usage, and 2) allow for earlier mobilization. Intervention: The (2020) LB cohort had a mixture of LB, bupivacaine HCL and normal saline injected into the fascial and subcutaneous layers of the incision prior to fascial closure. The (2019) control cohort had an epidural (EPI) catheter placed prior to fascial closure. The epidural infusion consisted of ropivacaine 0.1% (0.1-0.2 ml/kg/hr.) The cohorts received the same pain protocol (intravenous opioid with transition to oral opioid, as well as dexmedetomidine, acetaminophen, ketorolac, and diazepam). Measures and Analysis: Two cohorts of prospective AIS patients that underwent PSF were retrospectively reviewed. They were compared regarding age, BMI, average preoperative major Cobb angle, average preoperative kyphosis, VAS pain scores and narcotic consumption. Time to ambulation, and length of stay (LOS) were also evaluated.  Results: 159 AIS patients were reviewed. There were no preoperative differences between the 2020 LB cohort (n =101) and the 2019 EPI cohort (n = 58) when comparing age (14.3 vs.15.0 years), average BMI (21.7 vs.20.8 kg/m2), preoperative major Cobb (60.7° vs.60.3°), or average preoperative kyphosis (25.7° vs. 27.1°). The LB cohort consumed similar morphine equivalents during the initial 24 hrs. (37.8mg vs.37.3mg), but less at 24-48 hrs. (37.2mg vs 41.0mg) (p=0.031), and 48-72hrs (23.3mg vs. 29.6mg) (p=0.015). The LB cohort ambulated 6.8 hrs. sooner (17.1 vs 23.9 hrs.) (p=.0001). Summary: LB associated with less consumption of post-operative morphine equivalents and earlier ambulation.