title: Temporal linear mode complexity as a surrogate measure of the anesthetic drug effects during sevoflurane anesthesia.
abstract: BACKGROUND
  The aims of this study were to compare the stability, correlation with end-tidal sevoflurane, and area below the effect (AUCeffect) vs. time curves of temporal linear mode complexity (TLMC) and approximate entropy (ApEn) during sevoflurane anesthesia. Another study goal was to characterize the time course of the effects of sevoflurane.
  
  
  METHODS
  Electroencephalogram (EEG) parame1ter stability was evaluated using the coefficients of variation (CV) of the median baseline (E0 ), maximal (Emax ), and individual median E0 - Emax values. Correlations between sevoflurane concentration and EEG parameters were tested. AUCeffect vs. time curves of TLMC and ApEn were calculated to quantitate any decrease in central nervous system activities. A sigmoid Emax model was used for pharmacodynamic modeling.
  
  
  RESULTS
  TLMC and ApEn demonstrated CVs of 8.36 and 7.35 (for E0 ) and 19.61 and 13.45 (Emax ), respectively. The CVs of the individual median E0 - Emax values were 65.16 for TLMC and 59.97 for ApEn. The Spearman correlation coefficient was -0.3103 for TLMC and -0.3410 for ApEn (P < 0.001 for both parameters). The median AUCeffect value was 338.9 for TLMC and 246.5 for ApEn (P = 0.457). The final pharmacodynamic parameters estimated by sigmoid Emax models were described as follows; E0 : 0.614, 0.617, Emax : 0.334, 0.287, Ce50 : 5.48, 5.07 vol%, γ: 1.88, 2.01, ke0 : 0.306, 0.236 min (TLMC, ApEn).
  
  
  CONCLUSIONS
  TLMC is comparable to ApEn according to the univariate EEG descriptors of the effects of sevoflurane. A sigmoid Emax model well described the pharmacodynamics of sevoflurane for TLMC and ApEn.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Byung-Moon
authors.initials: BM
authors.lastname: Choi
authors.affiliation: Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
authors.forename: Eun-Hyo
authors.initials: EH
authors.lastname: Koh
authors.affiliation: Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
authors.forename: Mun-Gyu
authors.initials: MG
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.
authors.forename: Si-Young
authors.initials: SY
authors.lastname: Ok
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. ; Department of Clinical Pharmacology and Therapeutics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Gyu-Jeong
authors.initials: GJ
authors.lastname: Noh
keywords: Electroencephalogram; Pharmacology; Sevoflurane