title: Less isoflurane is required after than before cardiopulmonary bypass to maintain a constant bispectral index value.
abstract: OBJECTIVE
  To test whether patients require less volatile anesthetic after cardiopulmonary bypass (CPB).
  
  
  METHODS
  Prospective, observational clinical study.
  
  
  METHODS
  Cardiovascular operating rooms of a large teaching hospital.
  
  
  METHODS
  Twenty adult patients undergoing surgery with CPB.
  
  
  METHODS
  Subjects received a computer-controlled fentanyl infusion designed to maintain effect site concentrations of 3 ng/mL, combined with a variable amount of isoflurane.
  
  
  RESULTS
  The end-tidal isoflurane concentration associated with a target bispectral index of 55 was recorded during skin preparation, after sternotomy, during rewarming, and after separation from CPB. Adjusted, geometric mean (95% confidence intervals), end-tidal isoflurane concentrations associated with a bispectral index of 55 were 0.46% (0.38% to 0.58%) during skin preparation, 0.47% (0.39% to 0.58%) after sternotomy, 0.35% (0.29% to 0.42%) during rewarming, and 0.36% (0.31% to 0.43%) after separation from CPB. The last 2 concentrations (recorded near the end and after CPB) were significantly (p < 0.05) less than the first 2 concentrations (recorded before CPB).
  
  
  CONCLUSIONS
  Because the level of surgical stimulation was relatively constant and minimal at the times of the measurements, these results are consistent with a reduced need for isoflurane after compared with before CPB.
authors.affiliation: Department of Anesthesiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Lundell
authors.forename: P E
authors.initials: PE
authors.lastname: Scuderi
authors.forename: J F
authors.initials: JF
authors.lastname: Butterworth
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D002315:Cardiopulmonary Bypass; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane