Comparison of different monitors for measurement of nociception during general anaesthesia: a network meta-analysis of randomised controlled trials

Abstract

Background: To avoid underdosing or overdosing of analgesic medications, a variety of nociception monitors that use distinct techniques have been developed to quantify nociception during general anaesthesia. Although prior meta-analyses have examined the behaviour of nociception monitors vs standard care protocols, they did not include the potentially valuable data for monitor-to-monitor comparisons. In order to capture these data fully and compare the behaviour of these monitors, we conducted a systematic search and network meta-analysis.

Methods: We performed a Bayesian network meta-analysis on data obtained from a systematic search within PubMed, Embase, Web of Science, Cochrane Library, and EmCare databases. The search was aimed to detect relevant RCTs on the use of nociception monitoring versus standard care or versus other nociception devices(s) during general anaesthesia in adult patients. The primary endpoint was intraoperative opioid consumption, for which we calculated the standardised mean difference (SMD) of morphine equivalents (MEs). Secondary endpoints included postoperative opioid consumption and nausea or vomiting, extubation time, postoperative pain score, and time to discharge readiness. The risk of bias was assessed using the revised Cochrane Risk of Bias tool for randomised trials (RoB 2.0).

Results: Thirty-eight RCTs, including 3412 patients and studying five different types of nociception monitors, were included in the analyses: Nociception Level Monitor (NOL), Analgesia Nociception Index (ANI), Surgical Plethysmographic Index (SPI), Pupillometry (pupillary pain index [PPI] or pupil dilation reflex [PDR]), and the beat-by-beat cardiovascular depth of anaesthesia index (CARDEAN). Pupillometry showed a significant reduction in intraoperative opioid consumption compared with standard care (SMD -2.44 ME; 95% credible interval [CrI] -4.35 to -0.52), and compared with SPI (SMD -2.99 ME; 95% CrI -5.15 to -0.81). With respect to monitors other than pupillometry, no significant differences in opioid consumption were detected in comparison with standard care or other monitors. Pupillometry was associated with a longer time to discharge readiness from the PACU, whereas NOL was associated with shorter extubation times. No relevant differences in other secondary outcomes were found.

Conclusions: Apart from pupillometry, no monitors demonstrated a significant effect on intraoperative opioid consumption. Secondary outcomes indicate limited clinical benefit for patients when using these monitors.

Keywords: ANI monitor; CARDEAN; NOL monitor; SPI monitor; general anaesthesia; network meta-analysis; nociception monitoring; opioid consumption; perioperative outcomes; pupillometry.