Effect of opioid-free versus opioid-based strategies during multimodal anaesthesia on postoperative morphine consumption after bariatric surgery: a randomised double-blind clinical trial

BackgroundThe efficacy and safety of opioid-free anaesthesia during bariatric surgery remain debated, particularly when administering multimodal analgesia. As multimodal analgesia has become the standard of care in many centres, we aimed to determine if such a strategy coupled with either dexmedetomidine (opioid-free anaesthesia) or remifentanil with a morphine transition (opioid-based anaesthesia), would reduce postoperative morphine requirements and opioid-related adverse events.MethodsIn this prospective double-blind study, 172 class III obese patients having laparoscopic gastric bypass surgery were randomly allocated to receive either sevoflurane–dexmedetomidine anaesthesia with a continuous infusion of lidocaine and ketamine (opioid-free group) or sevoflurane–remifentanil anaesthesia with a morphine transition (opioid-based group). Both groups received at anaesthesia induction a bolus of magnesium, lidocaine, ketamine, paracetamol, diclofenac, and dexamethasone. The primary outcome was 24-h postoperative morphine consumption. Secondary outcomes included postoperative quality of recovery (QoR40), incidence of hypoxaemia, bradycardia, and postoperative nausea and vomiting (PONV).ResultsEighty-six patients were recruited in each group (predominantly women, 70% had obstructive sleep apnoea). There was no significant difference in postoperative morphine consumption (median inter-quartile range: 16 13–26 vs 15 10–24 mg, P=0.183). The QoR40 up to postoperative day 30 did not differ between groups, but PONV was less frequent in the opioid-free group (37% vs 59%, P=0.005). Hypoxaemia and bradycardia were not different between groups.ConclusionsDuring bariatric surgery, a multimodal opioid-free anaesthesia technique did not decrease postoperative morphine consumption when compared with a multimodal opioid-based strategy. Quality of recovery did not differ between groups although the incidence of PONV was less in the opioid-free group.Clinical trial registrationNCT05004519.