title: Comparative evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index monitor during propofol-remifentanil anesthesia.
abstract: BACKGROUND
  Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia.
  
  
  METHODS
  The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 microg/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 microg . kg(-1) . min(-1)) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability.
  
  
  RESULTS
  SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate.
  
  
  CONCLUSIONS
  SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.
authors.affiliation: Department of Anesthesiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. guschmid@uke.uni-hamburg.de
authors.forename: Gunter N
authors.initials: GN
authors.lastname: Schmidt
authors.forename: Petra
authors.initials: P
authors.lastname: Bischoff
authors.forename: Thomas
authors.initials: T
authors.lastname: Standl
authors.forename: Angelika
authors.initials: A
authors.lastname: Hellstern
authors.forename: Olaf
authors.initials: O
authors.lastname: Teuber
authors.forename: Jochen
authors.initials: J
authors.lastname: Schulte Esch
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000465:Algorithms; D000768:Anesthesia, General; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D001794:Blood Pressure / Q000187:drug effects; D016292:Procedural Sedation; D003243:Consciousness / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects* / Q000295:instrumentation*; D019277:Entropy; D005260:Female; D013509:Gynecologic Surgical Procedures; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007442:Intubation, Intratracheal; D016015:Logistic Models; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D010146:Pain / Q000503:physiopathology; D010812:Physical Stimulation; D010880:Piperidines; D011237:Predictive Value of Tests; D015742:Propofol; D000077208:Remifentanil
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol