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.
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.
Struys
Michel M R F
MM
Department of Anesthesia, University Hospital of Gent, Gent, Belgium. Michel.Struys@rug.ac.be
Jensen
Erik Weber
EW
Smith
Warren
W
Smith
N Ty
NT
Rampil
Ira
I
Dumortier
Frank J E
FJ
Mestach
Christel
C
Mortier
Eric P
EP
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
D015742:Propofol