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Ruetzler K, Montalvo M, Rotem OM, Ekrami E, Rossler J, Duran JAA, Dahan A, Gozal Y, Richebe P, Farhang B, Turan A, Sessler DI: Generalizability of nociception level as a measure of intraoperative nociceptive stimulation: A retrospective analysis. Acta Anaesthesiol Scand 2023; 67: 1187–1193

May 17, 2023

Background:
Nociception-guided intraoperative opioid administration might help reduce postoperative pain. A commonly used and validated nociception monitor sys- tem is nociception level (NOL), which provides the nociception index, ranging from 0 to 100, with 0 representing no nociception and 100 representing extreme nocicep- tion. We tested the hypothesis that NOL responses are similar in men and women given remifentanil and fentanyl, across various types of anesthesia, as a function of American Society of Anesthesiologists physical status designations, and over a range of ages and body morphologies.
Methods:
We conducted a retrospective cohort analysis of trial data from eight pro- spective NOL validation studies. Among 522 noncardiac surgical patients enrolled in these studies, 447 were included in our analysis. We assessed NOL responses to vari- ous noxious and non-noxious stimuli.
Results:
The average NOL in response to 315 noxious stimuli was 47 ± 15 (95% CI = 45–49). The average NOL in response to 361 non-noxious stimuli was 10 ± 12 (95% CI = 9–11). NOL responses were similar in men and women, in patients given remifentanil and fentanyl, across various types of anesthesia, as a function of Ameri- can Society of Anesthesiologists physical status designations, and over a range of ages and body morphologies.
Conclusion:
Nociception level appears to provide accurate estimates of intraoperative nociception over a broad range of patients and anesthetic conditions.
KEYWORDS analgesia, fentanyl, monitoring, nociception, pain, PMD-200.
Editorial Comment:
Estimation of the level of nociception is now possible during general anesthesia. In this reanaly- sis of data from eight studies, the authors assessed the nociception level index for events that were classified as either nociceptive or non-nociceptive. It was found that there was a large dif- ference in the nociception level index for these two types of events, and this was consistent across a number of characteristics such as age, sex, body mass index, and type of anesthesia. Not all events could, however, be classified. Readers can note competing interests for some coauthors.