Reduced postoperative pain using Nociception Level-guided fentanyl dosing during sevoflurane anaesthesia: a randomised controlled trial

Fleur Meijer,Maarten Honing,Tessa Roor,Samantha Toet,Paul Calis,Erik Olofsen,Chris Martini,Monique Van Velzen,Leon Aarts,Marieke Niesters,Martijn Boon,Albert Dahan

doi:10.1016/j.bja.2020.07.057

Fleur Meijer, Maarten Honing + Show 10 more

Open Access

https://doi.org/10.1016/j.bja.2020.07.057

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Abstract

BackgroundThe majority of postoperative patients report moderate to severe pain, possibly related to opioid underdosing or overdosing during surgery. Objective guidance of opioid dosing using the Nociception Level (NOL) index, a multiparameter artificial intelligence-driven index designed to monitor nociception during surgery, may lead to a more appropriate analgesic regimen, with effects beyond surgery. We tested whether NOL-guided opioid dosing during general anaesthesia results in less postoperative pain. MethodsIn this two-centre RCT, 50 patients undergoing abdominal surgery under fentanyl/sevoflurane anaesthesia were randomised to NOL-guided fentanyl dosing or standard care in which fentanyl dosing was based on haemodynamics. The primary endpoint of the study was postoperative pain assessed in the PACU. ResultsMedian postoperative pain scores were 3.2 (inter-quartile range 1.3–4.3) and 4.8 (3.0–5.3) in NOL-guided and standard care groups, respectively (P=0.006). Postoperative morphine consumption (standard deviation) was 0.06 (0.07) mg kg−1 (NOL-guided group) and 0.09 (0.09) mg kg−1 (control group; P=0.204). During surgery, fentanyl dosing was not different between groups (NOL-guided group: 6.4 [4.2] μg kg−1vs standard care: 6.0 [2.2] μg kg−1, P=0.749), although the variation between patients was greater in the NOL-guided group (% coefficient of variation 66% in the NOL-guided group vs 37% in the standard care group). ConclusionsDespite absence of differences in fentanyl and morphine consumption during and after surgery, a 1.6-point improvement in postoperative pain scores was observed in the NOL-guided group. We attribute this to NOL-driven rather than BP- and HR-driven fentanyl dosing during anaesthesia. Clinical trial registrationwww.trialregister.nl under identifier NL7845.

Highlights

The majority of postoperative patients report moderate to severe pain, possibly related to opioid underdosing or overdosing during surgery
Given all of the above, it is important to prevent high pain levels after surgery. As both opioid underdosing and overdosing during anaesthesia are associated with high postoperative pain scores, we designed a study in which we examined whether opioid dosing based on the individual nociceptive state of the patient during surgery, as measured by the Nociception Level (NOL) index, would improve postoperative pain scores
While the result of our study was affirmative, we show that the opioid dose given during surgery per se was not the determinant of reduced postoperative pain scores, as we observed similar cumulative fentanyl doses administered in the two treatment groups

Summary

Introduction

The majority of postoperative patients report moderate to severe pain, possibly related to opioid underdosing or overdosing during surgery. We tested whether NOL-guided opioid dosing during general anaesthesia results in less postoperative pain. Results: Median postoperative pain scores were 3.2 (inter-quartile range 1.3e4.3) and 4.8 (3.0e5.3) in NOL-guided and standard care groups, respectively (P1⁄40.006). Postoperative morphine consumption (standard deviation) was 0.06 (0.07) mg kgÀ1 (NOL-guided group) and 0.09 (0.09) mg kgÀ1 (control group; P1⁄40.204). Conclusions: Despite absence of differences in fentanyl and morphine consumption during and after surgery, a 1.6-point improvement in postoperative pain scores was observed in the NOL-guided group. We attribute this to NOL-driven rather than BP- and HR-driven fentanyl dosing during anaesthesia.

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