Opioid-free versus opioid-based anesthesia in laparoscopic bariatric surgery: an exploratory randomized pilot trial

Bariatric surgery is the most effective treatment for severe obesity, but perioperative pain control and prevention of postoperative nausea and vomiting (PONV) remain important clinical challenges. Opioid-free anesthesia (OFA) has been proposed as a strategy to reduce opioid-related adverse effects within multimodal perioperative care; however, evidence regarding its clinical benefits in bariatric surgery remains limited and heterogeneous.

In this prospective exploratory randomized pilot trial, 60 patients undergoing laparoscopic bariatric surgery were allocated in a 1:1 ratio to receive opioid-free anesthesia (OFA) or opioid-based anesthesia (OBA). The primary endpoint was postoperative pain intensity at post-anesthesia care unit (PACU) discharge. Secondary outcomes included pain at additional time points, need for rescue analgesia, PONV, intraoperative nociception assessed using the nociception level (NOL) index, and patient satisfaction. Adjusted analyses were performed using generalized linear and logistic regression models, accounting for clinically relevant baseline imbalances.

Sixty patients were randomized (OFA n = 30; OBA n = 30), with no losses to follow-up. OFA was associated with lower postoperative pain scores at PACU discharge and at 24 h, but not at hospital discharge. Although absolute differences in pain intensity were modest, the need for rescue analgesia was lower in the OFA group (30.0% vs. 73.3%), corresponding to an absolute risk reduction of 43.3% and a number needed to treat of approximately 3. Adjusted analyses were consistent with these findings, showing higher odds of requiring rescue analgesia in the OBA group (adjusted OR 6.5, 95% CI 1.8-23.2), although the wide confidence interval reflects considerable imprecision. The incidence of PONV was similar between groups, although interpretation is limited by unequal antiemetic prophylaxis. Intraoperative nociception, assessed using the NOL index in a subset of patients, showed lower values in the OFA group, although these findings are exploratory.

OFA was associated with modest reductions in postoperative pain and a clinically meaningful decrease in rescue analgesia requirements. These findings suggest that OFA may represent a promising opioid-sparing strategy but should be considered hypothesis-generating and require confirmation in larger, adequately powered multicentre randomized trials.

NCT07337135. Registered on 13th January 2026. Retrospectively registered.