Intraoperative monitoring of nociception for opioid administration: a meta-analysis of randomized controlled trials

Under-dosage or over-dosage of intraoperative analgesia can cause harm to patients. Many studies have demonstrated the clinical advantages of nociception monitoring tools, but with some conflicting results. To clarify the issue, this meta-analysis compared the effects of Analgesia Nociception Index (ANI), Surgical Pleth Index (SPI), and pupillometry monitoring methods with those of analgesia management practices of intraoperative opioid administration.

A comprehensive literature search was conducted to identify clinical trials that compared the effect of monitoring of nociception-antinociception balance (versus clinical signs) on intraoperative opioid administration. Meta-analysis was performed for intraoperative opioid administration, postoperative pain and rescue opioid consumption separately using fixed-effects model and random effects model. In addition, a subgroup analysis was also performed to determine the effects of age, study quality, anesthesia regimen, and nociception monitoring devices on intraoperative opioid administration.

Ten studies that used ANI, SPI, or pupillometry for intraoperative opioid guidance were identified. As a principle finding, nociception measurement-guided analgesia reduced intraoperative opioid consumption compared with conventional analgesia. In adults, SPI-guided intraoperative opioid administration was lower than conventional analgesia, whereas the difference between ANI-guided analgesia and standard clinical care was not statistically significant. Furthermore, in adults, anesthetized with sevoflurane, nociception monitoring decreased intraoperative analgesia doses.

Nociception monitoring devices seem to have an advantage over standard clinical practice on intraoperative management of analgesia during general anesthesia. Future research should focus on identifying appropriate indicators to objectively assess the degree of pain in children and perform large-scale multicenter trials to prove clinical advantages of nociception measurements during propofol anesthesia.