title: Auditory evoked potential index predicts the depth of sedation and movement in response to skin incision during sevoflurane anesthesia.
abstract: BACKGROUND
  The auditory evoked potential (AEP) index, which is a single numerical parameter derived from the AEP in real time and which describes the underlying morphology of the AEP, has been studied as a monitor of anesthetic depth. The current study was designed to evaluate the accuracy of AEPindex for predicting depth of sedation and anesthesia during sevoflurane anesthesia.
  
  
  METHODS
  In the first phase of the study, a single end-tidal sevoflurane concentration ranging from 0.5 to 0.9% was assigned randomly and administered to each of 50 patients. The AEPindex and the Bispectral Index (BIS) were obtained simultaneously. Sedation was assessed using the responsiveness portion of the observer's assessment of alertness-sedation scale. In the second phase of the study, 10 additional patients were included, and the 60 patients who were scheduled to have skin incisions were observed for movement in response to skin incision at the end-tidal sevoflurane concentrations between 1.6 and 2.6%. The relation among AEPindex, BIS, sevoflurane concentration, sedation score, and movement or absence of movement after skin incision was determined. Prediction probability values for AEPindex, BIS, and sevoflurane concentration to predict depth of sedation and anesthesia were also calculated.
  
  
  RESULTS
  The AEPindex, BIS, and sevoflurane concentration correlated closely with the sedation score. The prediction probability values for AEPindex, BIS, and sevoflurane concentration for sedation score were 0.820, 0.805, and 0.870, respectively, indicating a high predictive performance for depth of sedation. AEPindex and sevoflurane concentration successfully predicted movement after skin (prediction probability = 0.910 and 0.857, respectively), whereas BIS could not (prediction probability = 0.537).
  
  
  CONCLUSIONS
  Auditory evoked potential index can be a guide to the depth of sedation and movement in response to skin incision during sevoflurane anesthesia.
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, Japan. tadkur@hama-med.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kurita
authors.forename: M
authors.initials: M
authors.lastname: Doi
authors.forename: T
authors.initials: T
authors.lastname: Katoh
authors.forename: H
authors.initials: H
authors.lastname: Sano
authors.forename: S
authors.initials: S
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Mantzaridis
authors.forename: G N
authors.initials: GN
authors.lastname: Kenny
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D004569:Electroencephalography / Q000187:drug effects; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects*; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane