A Systematic Review and Meta-Analysis of Postoperative Opioid Consumption, Pain and Complications Following...

Autonomic nervous system-based nociception monitors have been proposed to optimise intraoperative opioid administration. While they reduce intraoperative opioid use, evidence on postoperative outcomes remains limited. We conducted a systematic review and meta-analysis to evaluate their effects on postoperative pain, opioid consumption and complications.

MEDLINE, EMBASE, LILACS, Google Scholar, Cochrane and ClinicalTrials.gov were searched for randomised controlled trials comparing intraoperative nociception monitoring with standard care and reporting postoperative outcomes. Risk of bias was assessed per Cochrane guidance. Data were pooled with random-effects models (RevMan 5.4.1). Continuous outcomes were summarised as mean or standardised mean differences (95% CI) and dichotomous outcomes as risk ratios (95% CI).

Thirty-eight RCTs comprising 3243 patients were included. Post-anaesthesia care unit (PACU) opioid consumption was lower in monitor-guided groups (mean difference -0.6 mg, 95% CI -1.00 to -0.19). Likewise, 24-h morphine consumption decreased (mean difference -2.56 mg, 95% CI -4.01 to -1.11); however, these reductions did not reach the minimal clinically important difference. PACU and 24-h pain scores, as well as the incidence of postoperative nausea and vomiting, respiratory events, urinary retention, delirium and chronic postsurgical pain (CPSP), were not significantly different between groups.

Intraoperative nociception monitors modestly reduce early postoperative opioid requirements, but without clinically meaningful benefit. No improvements were observed in postoperative pain or complications. These findings suggest that, despite their impact on intraoperative opioid titration, nociception monitors do not improve patient-centered postoperative outcomes.

This systematic review and meta-analysis shows that intraoperative autonomic nervous system-based nociception monitors significantly reduce postoperative opioid consumption at PACU discharge and 24 hours, but the effect size does not reach the minimal clinically important difference. Pain scores and postoperative complications are not significantly impacted. These findings suggest that, while nociception monitors influence intraoperative opioid titration, their clinical benefit on postoperative outcomes remains limited.

PROSPERO number: CRD42023490440; ClinicalTrials.gov identifier: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023490440.