Opioid-free anesthesia for minimally invasive abdominal surgery: a systematic review, meta-analysis, and trial sequential analysis

Abstract

Purpose: Opioid anesthesia is commonly employed in minimally invasive surgeries but is associated with adverse effects, including postoperative nausea and vomiting (PONV). Opioid-free anesthesia aims to mitigate these issues. We conducted a systematic review, meta-analysis, and trial sequential analysis (TSA) comparing opioid and opioid-free anesthesia in minimally invasive abdominal surgeries. Methods: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for randomized controlled trials (RCTs) comparing these approaches. Our primary outcomes were adverse effects (PONV, bradycardia), while secondary outcomes were pain, opioid consumption, and postanesthesia care unit (PACU) length of stay (LOS). We performed a TSA to investigate the conclusiveness of the results. Results: We included 26 RCTs encompassing 2,025 patients, with 1,009 (49%) in the opioid-free anesthesia group. Opioid-free anesthesia reduced PONV significantly (risk ratio, 0.55; 95% confidence interval [CI], 0.40 to 0.74; P < 0.001), but we found no significant differences in bradycardia rates. We found nonclinically relevant higher pain scores for opioid anesthesia (mean difference [MD], −0.9; 95% CI, −1.7 to −0.2; P = 0.01) and opioid consumption at 2 hr post surgery (MD, −5.4 mg oral morphine equivalents; 95% CI, −9.1 to −1.8; P = 0.004). We also noted a reduced time to first analgesia (MD, 88 min; 95% CI, 18 to 159; P = 0.01). We found no differences in PACU LOS. The TSA confirmed the sample size’s adequacy in showing PONV reduction with opioid-free anesthesia. Conclusion: Opioid-free anesthesia showed a significant reduction in PONV and a decrease in opioid consumption during the first 2 hr postoperatively, suggesting it can be an alternative to opioid anesthesia in minimally invasive abdominal surgeries. Study registration: PROSPERO (CRD42023492385); first submitted 18 December 2023.