title: Bispectral index, entropy, and quantitative electroencephalogram during single-agent xenon anesthesia.
abstract: BACKGROUND
  The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects.
  
  
  METHODS
  After mask induction with xenon and intubation, anesthesia was continued with xenon only. BIS, State Entropy and Response Entropy, and electroencephalogram were monitored throughout induction, steady-state anesthesia, and emergence. The performance of BIS, State Entropy, and Response Entropy were evaluated with prediction probability, sensitivity, and specificity analyses. The power spectrum of the raw electroencephalogram signal was calculated.
  
  
  RESULTS
  The mean (SD) xenon concentration during anesthesia was 66.4% (2.4%). BIS, State Entropy, and Response Entropy demonstrated low prediction probability values at loss of response (0.455, 0.656, and 0.619) but 1 min after that the values were high (0.804, 0.941, and 0.929). Thereafter, equally good performance was demonstrated for all indices. At emergence, the prediction probability values to distinguish between steady-state anesthesia and return of response for BIS, State Entropy, and Response Entropy were 0.988, 0.892, and 0.992. No statistical differences between the performances of the monitors were observed. Quantitative electroencephalogram analyses showed generalized increase in total power (P < 0.001), delta (P < 0.001) and theta activity (P < 0.001), and increased alpha activity (P = 0.003) in the frontal brain regions.
  
  
  CONCLUSIONS
  Electroencephalogram-derived depth of sedation indices BIS and Entropy showed a delay to detect loss of response during induction of xenon anesthesia. Both monitors performed well in distinguishing between conscious and unconscious states during steady-state anesthesia. Xenon-induced changes in electroencephalogram closely resemble those induced by propofol.
authors.affiliation: Turku Positron Emission Tomography (PET) Centre, and Department of Anesthesiology and Intensive Care, Turku University Hospital, Turku, Finland. ruut.laitio@tyks.fi
authors.forename: Ruut M
authors.initials: RM
authors.lastname: Laitio
authors.forename: Kimmo
authors.initials: K
authors.lastname: Kaskinoro
authors.forename: Mika O K
authors.initials: MO
authors.lastname: Särkelä
authors.forename: Kaike K
authors.initials: KK
authors.lastname: Kaisti
authors.forename: Elina
authors.initials: E
authors.lastname: Salmi
authors.forename: Anu
authors.initials: A
authors.lastname: Maksimow
authors.forename: Jaakko W
authors.initials: JW
authors.lastname: Långsjö
authors.forename: Riku
authors.initials: R
authors.lastname: Aantaa
authors.forename: Katja
authors.initials: K
authors.lastname: Kangas
authors.forename: Satu
authors.initials: S
authors.lastname: Jääskeläinen
authors.forename: Harry
authors.initials: H
authors.lastname: Scheinin
mesh_terms: D000328:Adult; D000769:Anesthesia, Inhalation / Q000379:methods*; D004569:Electroencephalography / Q000187:drug effects* / Q000379:methods*; D019277:Entropy; D006801:Humans; D008297:Male; D014978:Xenon
chemical_list: D014978:Xenon