Quadratus lumborum block for postoperative analgesia after full abdominoplasty: a randomized controlled trial

The quadratus lumborum block (QLB) provides regional analgesia of the anterior abdominal wall, theoretically matching the postoperative pain after postbariatric standard full abdominoplasty. We investigated the effectiveness of a QLB as an addition to the current multimodal analgesia regimen in postbariatric patients treated with standard full abdominoplasty.

Randomized, placebo-controlled, triple blinded study (n = 50). All patients received perioperative paracetamol and intraoperative local anesthetic infiltration. QLB was administered bilaterally before induction of general anesthesia with 2 × 20 mL of either ropivacaine 3.75 mg/mL (n = 25) or placebo (saline 9 mg/mL) (n = 25). Patients received intravenous patient controlled opioid analgesia postoperatively. The primary endpoint was opioid use during the first 24 postoperative hours. Secondary endpoints were acute and chronic postoperative pain, postoperative nausea and vomiting, and other side effects.

Patient characteristics were similar between groups. The primary endpoint in morphine equivalent units was similar between groups during the first 24 h with mean (SD) of 26 (25) vs. 33 (33) mg (p = 0.44) in the ropivacaine and placebo group, respectively. The observed effect was smaller, and SD larger than assumed in the sample size estimation. Linear mixed effects modeling indicated a minimal inter-group difference. No differences were found for secondary endpoints.

The QLB did not provide significant additional benefit in terms of reduced opioid requirements or secondary endpoints when administered as part of a multimodal pain regimen to postbariatric patients undergoing standard full abdominoplasty. A minimal difference of little clinical importance the first 12 postoperative hours may have been missed.

Including the QLB in the current multimodal pain regimen cannot be recommended based on these findings. The study does not preclude QLB use in individual cases where the multimodal regimen is inadequate or contraindicated. The effectiveness of the QLB for supraumbilical pain remains undocumented.