title: Performance of the ARX-derived auditory evoked potential index as an indicator of anesthetic depth: a comparison with bispectral index and hemodynamic measures during propofol administration.
abstract: BACKGROUND
  Autoregressive modeling with exogenous input of middle-latency auditory evoked potential (A-Line autoregressive index [AAI]) has been proposed for monitoring anesthetic depth. The aim of the current study was to compare the accuracy of this new index with the Bispectral Index (BIS), predicted effect-site concentration of propofol, and hemodynamic measures.
  
  
  METHODS
  Twenty female patients scheduled for ambulatory gynecologic surgery received effect compartment controlled infusion of propofol. Target effect-site concentration was started at 1.5 microg/ml and increased every 4 min by 0.5 microg/ml. At every step, sedation level was compared with monitoring values using different clinical scoring systems and reaction to noxious stimulus.
  
  
  RESULTS
  Bispectral Index, AAI, and predicted propofol effect-site concentration were accurate indicators for the level of sedation and loss of consciousness. Hemodynamic variables were poor indicators of the hypnotic-anesthetic status of the patient. BIS correlated best with propofol effect-site concentration, followed by AAI. Hemodynamic measurements did not correlate well. No indicators predicted reaction to noxious stimulus. Poststimulus, BIS and AAI showed an increase as a result of arousal. This reaction occurred more rapidly with the AAI than with BIS.
  
  
  CONCLUSIONS
  Bispectral Index, AAI, and predicted propofol effect-site concentration revealed information on the level of sedation and loss of consciousness but did not predict response to noxious stimulus.
authors.affiliation: Department of Anesthesia, University Hospital of Gent, Gent, Belgium. Michel.Struys@rug.ac.be
authors.forename: Michel M R F
authors.initials: MM
authors.lastname: Struys
authors.forename: Erik Weber
authors.initials: EW
authors.lastname: Jensen
authors.forename: Warren
authors.initials: W
authors.lastname: Smith
authors.forename: N Ty
authors.initials: NT
authors.lastname: Smith
authors.forename: Ira
authors.initials: I
authors.lastname: Rampil
authors.forename: Frank J E
authors.initials: FJ
authors.lastname: Dumortier
authors.forename: Christel
authors.initials: C
authors.lastname: Mestach
authors.forename: Eric P
authors.initials: EP
authors.lastname: Mortier
mesh_terms: D000293:Adolescent; D000328:Adult; D000771:Anesthesia, Intravenous; D003243:Consciousness; D004569:Electroencephalography / Q000187:drug effects*; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D009068:Movement; D015742:Propofol / Q000494:pharmacology*; D012680:Sensitivity and Specificity
chemical_list: D015742:Propofol