Comparing Efficacy of Oxycodone versus Sufentanil for Postoperative Recovery in Patients Receiving Bilateral Modified Thoracoabdominal Nerves Block Through Perichondrial Approach (M-TAPA) Following Laparoscopic Radical Distal Gastrectomy: A Study Protocol for a Prospective, Blinded, Randomized Controlled Trial.

Introduction: While laparoscopic radical distal gastrectomy (LRDG) has been widely adopted for its minimally invasive benefits in the treatment of gastric cancer, acute postoperative pain, comprising both somatic incisional pain and visceral discomfort, remains a clinical challenge that can affect patients' perioperative comfort and the rehabilitation process. Consequently, optimizing postoperative analgesic strategies remains essential for enhanced recovery. The modified thoracoabdominal nerves block through a perichondrial approach (M-TAPA) has been introduced as an emerging regional analgesic technique for upper abdominal incisions. In the regard of effective management of visceral pain, oxycodone is a unique agonist at κ-opioid receptors and potentially influences inhibiting visceral nociceptive transmission better than sufentanil. Therefore, this study aims to evaluate whether the combination of M-TAPA with oxycodone-based patient-controlled intravenous analgesia (PCIA) is more effective to provide analgesia efficacy and facilitate gastrointestinal recovery compared to a sufentanil-based analgesic regimen. Methods/Analysis: This single-center, prospective, double-blind, randomized controlled trial will enroll 96 patients scheduled for elective laparoscopic radical distal gastrectomy. Eligible patients will be randomly assigned at a 1:1 ratio to receive either Oxycodone PCIA (Group O) or Sufentanil PCIA (Group S). Both groups will receive bilateral ultrasound-guided M-TAPA before surgical incision. The primary outcome is the Quality of Recovery-15 (QoR-15) score assessed at 24 hours postoperatively. Secondary outcomes include static and dynamic numeric rating scale (NRS) pain scores, cumulative opioid consumption (converted to intravenous morphine equivalents), clinical recovery milestones, and the incidence of adverse events such as postoperative nausea and vomiting (PONV) and respiratory depression. Ethics and Dissemination: This trial was approved by the Ethics Committee of Beijing Friendship Hospital, Capital Medical University on August 28, 2025. The trial started recruiting patients after being registered on the Chinese Clinical Trial Registry. Trial Registration Number: ChiCTR2600119394.