Comparison of ultrasound-guided anterior quadratus lumborum block at the lateral supra-arcuate ligament with posterior quadratus lumborum block for perioperative analgesia in laparoscopic nephrectomy: a protocol for a randomised, prospective, parallel group, non-inferior trial

Objective Anterior quadratus lumborum block at the lateral supra-arcuate ligament (QLBA) is a new method for postoperative pain relief in patients undergoing abdominal surgery. Perioperative QLBA is effective, but it has not been compared with posterior quadratus lumborum block (QLB2). The present study aims to evaluate the postoperative pain of patients undergoing laparoscopic nephrectomy surgery with QLBA versus QLB2. Methods/design This study is a randomised, prospective, parallel group, non-inferior trial. All patients undergoing laparoscopic nephrectomy surgery will be randomised 1:1 to the QLBA group or the QLB2 group with general anaesthesia. The objective of the trial is to evaluate the postoperative pain of patients undergoing laparoscopic nephrectomy surgery with QLBA (n=50) versus QLB2 (n=50). The primary outcome for this trial is the Visual Analogue Scale scores at rest and activity (dynamic pain scores are assessed with a cough or a trial to sit up in bed) 2 hours after surgery between patients who receive QLBA versus QLB2. The secondary objectives will be to compare (1) pain at rest and activity 0.5 hour, 2 hours, 24 hours, 48 hours after surgery; (2) the time spent on block operation; (3) the blocked dermatomal coverage 5 min and 15 min after block operation; (4) intraoperative opioid consumption; (5) types and doses of the rescue analgesic after surgery; (6) nausea and vomiting score within 24 hours after surgery; (7) time from the end of surgery to the first onset significant pain; (8) patient satisfaction score. Discussion Clinical experience has supported that QLB is a very effective postoperative analgesic method, and we will answer the following questions in this trial: Will both approaches have the same analgesic effect and duration? Will the QLBA have a non-inferior postoperative analgesic effect compared with QLB2 or the QLBA be able to prolong the duration of analgesia after surgery? The results of this study could have actual clinical applications that could help to reduce postoperative pain and shorten hospital stays. Ethics and dissemination The study design was approved by the ethical committee of Beijing Chao-Yang Hospital, Beijing, China (2020-ke-321). The trial results will be published in peer-reviewed journals and at conferences.