Evaluation of analgesic effects and safety of quadratus lumborum block in patients undergoing laparoscopic surgery: a meta-analysis of randomized controlled trials.

Introduction: Recent years have witnessed the rapid expansion of quadratus lumborum block (QLB) technique in laparoscopic surgeries. However, inconsistent conclusions from latest studies prompted us to conduct present study to evaluate comprehensively the effects of QLB in patients undergoing laparoscopic surgery.

Evidence Acquisition: Databases including PubMed, Embase, and Cochrane Library were searched from inception to March 2021 by us. Randomized controlled trials comparing QLB versus placebo or different block techniques were involved. Co-primary outcomes included number of patients requiring additional analgesia, opioids consumption and incidence of postoperative nausea/vomiting (PONV).

Evidence Synthesis: Data from 20 studies involving a total of 1,332 patients were acquired. Based on the current evidences, the results indicated that application of QLB was associated with less number of patients requiring additional analgesia (RR=0.67, with 95% CI [0.49, 0.91]), reduced intraoperative opioid consumption (SMD -0.97 with 95% CI [-1.48, -0.45]) and postoperative opioid consumption (SMD -19.12 with 95% CI [-34.83, -3.41]), and less incidence of postoperative nausea and vomiting (RR=0.71, with 95% CI [0.58, 0.87]) compared to placebo. In addition, no significant intergroup (QLB vs. different regional block techniques) differences were observed for most outcomes.

Conclusions: Current evidence exhibited several superiorities of QLB for patients in laparoscopic surgeries. Differences between QLB and some other block techniques in analgesic effects and PONV controlling effects were not significant. However, it calls for more high-quality evidence with large samples and trials with consistent evaluation scales for pain evaluation to draw more reliable conclusions.