Usefulness of analgesia nociception index for guiding intraoperative opioid administration: a systematic review and meta-analysis

INTRODUCTION: This study primarily aimed at investigating the efficacy of Analgesia Nociception Index (ANI) for guiding intraoperative opioid administration in patients receiving surgery under general anesthesia. eviDence acQUisition: the Medline, embase, google scholar, and the cochrane library databases were searched from inception to april 2022 for randomized controlled trials. the primary outcome was intraoperative opioid adminis-tration, while the secondary outcomes included postoperative opioid consumption, pain score, emergency time, risk of nausea/vomiting (PONV), and Postanesthesia Care Unit (PACU) stay. EVIDENCE SYNTHESIS: Six studies including 399 participants (published from 2015 to 2022) focused on non-cardiac surgery, including spine surgery (two trials), breast surgery (two trials), gynecologic surgery (one trial), and laparoscopic cholecystectomy (one trial) were included. Meta-analysis revealed no difference in intraoperative opioid administration with the use of ANI-guided analgesia compared to the control group that used conventional clinical measurements (e.g., heart rate) to guide opioid use [standardized mean difference (SMD)=-0.17, 95% CI: -0.56 to 0.22, P=0.39, I2=72%, six trials, 399 participants]. gender-based subgroup analysis showed effectiveness of ani for reducing opioid administration in female patients (SMD=-0.53, P=0.02). There were no differences in postoperative recovery characteristics including pain score [Mean difference (MD): -0.03, P=0.79], opioid consumption (SMD: -0.34, P=0.08), emergence time (MD=1.12, P=0.47), length of stay in the PACU (MD: -0.56, P=0.83), and risk of PONV [risk ratio(RR): 0.75, P=0.46] between the two groups. conclUsions: analgesia nociception index-guided analgesia was unable to reduce intraoperative opioid administra-tion compared to monitoring using conventional clinical parameters. Further studies are required to support our findings.