title: Ability of the nociception level, a multiparameter composite of autonomic signals, to detect noxious stimuli during propofol-remifentanil anesthesia.
abstract: BACKGROUND
  A novel multidimensional index of nociception, the nociception level (NoL) index, derived from the nonlinear composite of heart rate (HR), HR variability, amplitude of the photoplethysmogram, skin conductance, fluctuations in skin conductance, and their time derivatives, was used to assess nociception during anesthesia.
  
  
  METHODS
  Seventy-two American Society of Anesthesiologists I to III patients received propofol (target bispectral index, 45) and one of six remifentanil target concentrations in the range of 0 to 5 ng/ml. The NoL, mean arterial pressure (MAP; derived from a beat-to-beat finger cuff measurement), and HR were measured during nonnoxious, moderate noxious (skin incision), and intense noxious (intubation) stimulation. Values are represented as average (95% CI).
  
  
  RESULTS
  NoL, HR, and MAP did not change during nonnoxious events. Incision increased HR by 1.3/min (-0.46 to 3.1/min; not significant), MAP by 7.9 mmHg (-1.9 to 13.0 mmHg; not significant), and NoL by 8.0 (0.4 to 16.0; P < 0.001). Intubation increased HR by 7.0/min (1.4 to 12.0/min; P < 0.001), MAP by 13.0 mmHg (3.1 to 20 mmHg; P < 0.001), and NoL by 18.0 (7.8 to 29.0; P < 0.001). The ΔNoL area under the curve (0.95) of the receiver operating characteristic curve was greater compared with ΔHR (0.84, P < 0.001) and ΔMAP (0.78, P < 0.001). Under nonnociceptive conditions, remifentanil had no effect on NoL, in contrast to HR and MAP that showed a dose-dependent decrease.
  
  
  CONCLUSIONS
  The NoL is a reliable measure of moderate and intense noxious stimulation and outperforms HR and MAP in differentiating noxious from nonnoxious stimuli. In contrast to HR and MAP, the NoL was not affected by hemodynamic effects of remifentanil.
authors.affiliation: From the Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Chris H
authors.initials: CH
authors.lastname: Martini
authors.forename: Martijn
authors.initials: M
authors.lastname: Boon
authors.forename: Suzanne J L
authors.initials: SJ
authors.lastname: Broens
authors.forename: Evelien F
authors.initials: EF
authors.lastname: Hekkelman
authors.forename: Lisanne A
authors.initials: LA
authors.lastname: Oudhoff
authors.forename: Anna Willemijn
authors.initials: AW
authors.lastname: Buddeke
authors.forename: Albert
authors.initials: A
authors.lastname: Dahan
mesh_terms: D000328:Adult; D000368:Aged; D000771:Anesthesia, Intravenous; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D017558:Elective Surgical Procedures; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods* / Q000592:standards; D010147:Pain Measurement / Q000379:methods* / Q000592:standards; D010880:Piperidines / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage*; D011446:Prospective Studies; D000077208:Remifentanil; D055815:Young Adult
chemical_list: D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol