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

Abstract

Background: The 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.

Methods: In 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).

Results: Eighty-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.

Conclusions: During 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 registration: NCT05004519.

Keywords: dexmedetomidine; enhanced recovery after surgery; hypoxaemia; nausea; nociception; pain; remifentanil; vomiting.

Fig 1

Study medications and timing. The study intervention consisted of four blinded interventions administered with a 100-ml infusion bag, a 1-ml syringe, and two 50-ml syringes. All medications were administered according to ideal bodyweight. OBA, opioid-based anaesthesia group; OFA, opioid-free anaesthesia group; PACU, post-anaesthesia care unit.

Fig 2

Consort flowchart. OBA, opioid-based anaesthesia group; OFA, opioid-free anaesthesia group.

Fig 3

Primary outcome of total postoperative morphine consumption. Box plot presentation (median, percentiles 25–75 and min-max).OBA, opioid-based anaesthesia group; OFA, opioid-free anaesthesia group.

Fig 4

Quality of recovery-40 questionnaire scores. Scores were measured before surgery, 1 day after surgery, and 30 days after surgery. OFA, opioid-free anaesthesia group; OBA, opioid-based anaesthesia group; QoR-40, Quality of recovery-40. ∗P<0.001 vs preop; ^†P<0.001 vs postoperative day 1.