Effect of nociception level index‐guided intra‐operative analgesia on early postoperative pain and opioid consumption: a systematic review and meta‐analysis

Summary Acute postoperative pain remains a critical treatment priority and has prompted a search for technologies and techniques to assist with intra‐operative analgesic monitoring and management. Anaesthetists traditionally rely on clinical judgement to guide intra‐operative analgesia, but several emerging technologies such as the nociception level index herald the possibility of routine intra‐operative analgesia monitoring. However, the impact of devices like nociception level index on postoperative outcomes has not been proven. We undertook a systematic review and meta‐analysis of articles which compared nociception level index‐guided analgesia to standard care. The primary outcomes were pain intensity and opioid consumption during the first 60–120 min after surgery. Secondary outcomes were the incidence of postoperative nausea and vomiting and duration of stay in the post‐anaesthesia care unit. Ten studies, collectively including 662 patients and published between 2019 and 2023, met inclusion criteria for both the qualitative systematic review and quantitative meta‐analysis. Risk of methodological bias was generally low or unclear, and six studies reported a significant conflict of interest relevant to their findings. Our meta‐analysis was performed using a random‐effects model. It found statistically significant benefits of nociception level index‐guided analgesia for early postoperative pain (mean (95%CI) difference ‐0.46 (‐0.88 to ‐0.03) on an 11‐point scale, p = 0.03), and opioid requirement (mean (95%CI) difference ‐1.04 (‐1.94 to ‐0.15) mg intravenous morphine equivalent, p = 0.02). Our meta‐analysis of the current literature finds that nociception level index‐guided analgesia statistically significantly reduces reported postoperative pain intensity and opioid consumption but fails to show clinically relevant outcomes. We found no evidence that nociception level index‐guided analgesia affected postoperative nausea and vomiting nor duration of stay in the post‐anaesthesia care unit.