title: Monitoring the nociception level: a multi-parameter approach.
abstract: The aim of the present study was to develop and validate an objective index for nociception level (NoL) of patients under general anesthesia, based on a combination of multiple physiological parameters. Twenty-five patients scheduled for elective surgery were enrolled. For clinical reference of NoL, the combined index of stimulus and analgesia was defined as a composite of the surgical stimulus level and a scaled effect-site concentration of opioid. The physiological parameters heart rate, heart rate variability (0.15-0.4 Hz band power), plethysmograph wave amplitude, skin conductance level, number of skin conductance fluctuations, and their time derivatives, were extracted. Two techniques to incorporate these parameters into a single index representing the NoL have been proposed: NoLlinear, based on an ordinary linear regression, and NoLnon-linear, based on a non-linear Random Forest regression. NoLlinear and NoLnon-linear significantly increased after moderate to severe noxious stimuli (Wilcoxon rank test, p < 0.01), while the individual parameters only partially responded. Receiver operating curve analysis showed that NoL index based on both techniques better discriminated noxious and non-noxious surgical events [area under curve (AUC) = 0.97] compared with individual parameters (AUC = 0.56-0.74). NoLnon-linear better ranked the level of nociception compared with NoLlinear (R = 0.88 vs. 0.77, p < 0.01). These results demonstrate the superiority of multi-parametric approach over any individual parameter in the evaluation of nociceptive response. In addition, advanced non-linear technique may have an advantage over ordinary linear regression for computing NoL index. Further research will define the usability of the NoL index as a clinical tool to assess the level of nociception during general anesthesia.
authors.affiliation: Medasense Biometrics Ltd., Ramat Yishai, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Ben-Israel
authors.forename: Mark
authors.initials: M
authors.lastname: Kliger
authors.forename: Galit
authors.initials: G
authors.lastname: Zuckerman
authors.forename: Yeshayahu
authors.initials: Y
authors.lastname: Katz
authors.forename: Ruth
authors.initials: R
authors.lastname: Edry
mesh_terms: D000328:Adult; D000698:Analgesia; D000768:Anesthesia, General / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000627:therapeutic use; D019540:Area Under Curve; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D059225:Nociception; D010146:Pain; D010147:Pain Measurement / Q000379:methods*; D010991:Plethysmography; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012044:Regression Analysis; D012867:Skin / Q000473:pathology; D013514:Surgical Procedures, Operative
chemical_list: D018686:Anesthetics, Intravenous