Anterior Quadratus Lumborum Block for Microvascular Free-Flap Breast Reconstruction: A Propensity-Score-Weighted Study

Abstract

Background: As part of a Continuous Quality Improvement (CQI) project for microsurgical free-flap breast reconstruction, anesthesia preoperatively placed an anterior quadratus lumborum block (aQLB) to replace the surgeon's intraoperatively placed transversus abdominis plane (sTAP) in its existing institutional early recovery after surgery (ERAS) protocol. We hypothesize that aQLB is superior to sTAP in Deep Inferior Epigastric Artery Perforator (DIEP) pain control and functional recovery.

Methods: A total of 413 patients were included, 254 patients (before CQI) received sTAP with bupivacaine plus liposomal bupivacaine were compared 159 patients (after CQI) received aQLB using bupivacaine plus dexamethasone sodium phosphate (DXP) and methylprednisolone acetate (MPA). The primary outcome was average daily opioid consumption in milligram morphine equivalents (MME). Secondary outcomes included average daily pain scores, total perioperative and postoperative opioid consumption, time to first ambulation, length of stay (LOS) in the post-anesthesia care unit (PACU) and hospital, and adverse events during hospitalization. Outcomes were analyzed using the stabilized inverse propensity of treatment weighting (sIPSW), and for secondary outcomes, false discovery rate (FDR) adjusted P values were used.

Results: Compared to sTAP, the aQLB group did not show a significant decrease in average daily, total perioperative, or total postoperative opioid consumption. The average pain score in the aQLB group is 0.71 higher than sTAP, P < .001. The statistical significance of shorter PACU LOS and hospital LOS was lost after sIPTW and false discovery rate (FDR) adjustment, only the statistically significant reduction in the time to first ambulation was maintained (0.83 [0.72-0.94], P = .015).

Conclusion: When compared to intraoperative sTAP with liposomal bupivacaine, pre-operative ultrasound-guided aQLB with DXP and MPA is an effective alternative, leading to similar opioid consumption and earlier ambulation for DIEP flap reconstruction.