Comparison of postoperative morphine requirements between an opioid-based anesthetic technique and an opioid-free technique in morbidly obese patients undergoing bariatric surgery

Abstract

Background: Opioid-free anesthesia (OFA) has gained increasing attention as a strategy to reduce opioid-related adverse effects, particularly in patients with obesity undergoing bariatric surgery. However, evidence regarding its impact on postoperative opioid consumption and pain control remains inconsistent. This study aimed to compare postoperative morphine requirements and clinical outcomes between OFA and opioid-based anesthesia (OBA) in bariatric surgery. Methods: In this retrospective observational study, 70 patients undergoing laparoscopic bariatric surgery (sleeve gastrectomy or Roux-en-Y gastric bypass) were included. Patients received either opioid-free total intravenous anesthesia (TIVA-OFA) or opioid-based total intravenous anesthesia (TIVA-OBA). The OFA protocol included propofol, dexmedetomidine, ketamine, lidocaine, and magnesium, whereas the OBA protocol consisted of propofol with remifentanil and fentanyl. The primary outcome was cumulative morphine consumption during the first 48 postoperative hours. Secondary outcomes included postoperative pain scores (VAS), Ramsay sedation scale, and perioperative adverse events. Results: Seventy patients were analyzed (35 per group). Baseline demographic characteristics were comparable between groups. Total postoperative morphine consumption at 48 hours was significantly lower in the OFA group compared with the OBA group (2.03 mg vs 11.56 mg). Patients receiving OFA also showed significantly lower postoperative pain scores during the early postoperative period. Postoperative nausea, vomiting, and hypoxemia occurred less frequently in the OFA group, whereas transient intraoperative bradycardia and hypotension were more common but clinically manageable. Conclusion: In patients undergoing bariatric surgery, opioid-free anesthesia significantly reduced postoperative morphine consumption and early postoperative pain compared with opioid-based anesthesia. These findings support the feasibility of OFA as an opioid-sparing strategy in bariatric anesthesia.