title: Spectral entropy as an electroencephalographic measure of anesthetic drug effect: a comparison with bispectral index and processed midlatency auditory evoked response.
abstract: BACKGROUND
  The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line ARX Index (AAI) and the Bispectral Index (BIS) and as measures of anesthetic drug effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AAI, and BIS to the calculated propofol effect-site concentration (Ceprop).
  
  
  METHODS
  With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI, and BIS were continuously recorded. Ceprop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ceprop and the electroencephalographic measures of drug effect were estimated using nonlinear mixed effect modeling.
  
  
  RESULTS
  Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed effect modeling generated reasonable models relating all four measures to Ceprop.
  
  
  CONCLUSIONS
  Compared with BIS and AAI, both SE and RE seem to be useful electroencephalographic measures of anesthetic drug effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ceprop was best for BIS.
authors.affiliation: Department of Anesthesia, Ghent University Hospital, Ghent, Belgium.
authors.forename: Ann L G
authors.initials: AL
authors.lastname: Vanluchene
authors.forename: Hugo
authors.initials: H
authors.lastname: Vereecke
authors.forename: Olivier
authors.initials: O
authors.lastname: Thas
authors.forename: Eric P
authors.initials: EP
authors.lastname: Mortier
authors.forename: Steven L
authors.initials: SL
authors.lastname: Shafer
authors.forename: Michel M R F
authors.initials: MM
authors.lastname: Struys
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D004569:Electroencephalography / Q000187:drug effects*; D019277:Entropy; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D013509:Gynecologic Surgical Procedures; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000097:blood; D011237:Predictive Value of Tests; D015742:Propofol; D013519:Urogenital Surgical Procedures
chemical_list: D018686:Anesthetics, Intravenous; D010100:Oxygen; D015742:Propofol