title: The influence of sevoflurane on the bispectral index, regional cerebral oxygen saturation, and propofol concentration during propofol/N2O anesthesia.
abstract: OBJECTIVE
  This study was undertaken to investigate the influence of sevoflurane on the bispectral index (BIS), regional cerebral oxygen saturation (rSO(2)), and serum propofol concentration during propofol/N(2)O anesthesia. This study tested the hypothesis that sevoflurane affect BIS values, rSO(2), and the pharmacokinetics of propofol during propofol/ N(2)O anesthesia.
  
  
  METHODS
  General anesthesia was administered to 15 ASA I-II patients with a continuous infusion of propofol to maintain a BIS value of 45 +/- 5. After recording baseline values, patients were assigned to receive sevoflurane (2.0%, 20 min). BIS values, rSO(2) using near-infrared spectroscopy, and hemodynamic parameters were recorded for 60 min. Cardiac output (CO) and stroke volume (SV) were evaluated using impedance cardiograph methods. Propofol concentration was determined using high-performance liquid chromatography.
  
  
  RESULTS
  Sevoflurane (2.0%, 20 min) decreased the BIS score from 47.4 +/- 8.2 to 27.3 +/- 5.9 (P < 0.01, n = 15) without affecting rSO(2). Sevoflurane decreased systolic blood pressure from 112.1 +/- 14.0 mmHg to 96.5 +/- 13.2 mmHg (P < 0.001, n = 15) without affecting heart rate. Both CO and SV were significantly decreased during sevoflurane application. Propofol concentration was increased from 2.71 +/- 0.51 microg/ml to 3.30 +/- 0.57 microg/ml (P < 0.05) after sevoflurane application, and was returned to baseline after sevoflurane washout.
  
  
  CONCLUSIONS
  We have shown that sevoflurane decreases BIS values during propofol/N(2)O anesthesia without affecting rSO(2) and that this change is accompanied by an increase in serum propofol concentration. Changes in propofol concentration may be due to, at least in part, hemodynamic changes such as decreased CO produced by sevoflurane.
authors.affiliation: Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi City, 371-8511, Japan. nishikaw@med.gunma-u.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kanemaru
authors.forename: Ryuji
authors.initials: R
authors.lastname: Hagiwara
authors.forename: Fumio
authors.initials: F
authors.lastname: Goto
mesh_terms: D000328:Adult; D000368:Aged; D018685:Anesthetics, Inhalation / Q000008:administration & dosage* / Q000097:blood; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002302:Cardiac Output / Q000187:drug effects; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008738:Methyl Ethers / Q000008:administration & dosage*; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009609:Nitrous Oxide / Q000008:administration & dosage; D010100:Oxygen / Q000378:metabolism*; D015742:Propofol / Q000008:administration & dosage* / Q000097:blood; D000077149:Sevoflurane; D014474:Unconsciousness / Q000503:physiopathology
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide; D010100:Oxygen; D015742:Propofol