title: Impact of bispectral index monitoring on stress response and propofol consumption in patients undergoing coronary artery bypass surgery.
abstract: BACKGROUND
  Bispectral Index (BIS)-titrated administration allows a reduction of propofol infusion rates in patients undergoing surgery. Resulting differences in anesthetic depth might affect the stress response to surgery involving neural circuitry not reflected in the electroencephalogram.
  
  
  METHODS
  Forty patients scheduled to undergo elective coronary artery bypass grafting receiving a background infusion of remifentanil (0.3 microg . kg . min) were anesthetized with intravenous propofol delivered by target-controlled infusion according to the Marsh pharmacokinetic model under BIS monitoring. In a randomized, prospective design, 20 patients received propofol at a target concentration of 3 microg/ml, whereas in 20 patients propofol was titrated to maintain a BIS value of 40-50. Plasma concentrations of propofol (by means of gas chromatography-mass spectrometry), epinephrine, norepinephrine (by means of high-pressure liquid chromatography), cortisol (by means of radioimmunoassay), and interleukins 6 and 10 (by means of enzyme-linked immunosorbent assay) were measured repeatedly throughout surgery.
  
  
  RESULTS
  BIS monitoring allowed a 30% reduction of propofol infusion rates and a similar decrease in plasma propofol concentrations in the BIS group without affecting the stress response to surgery for the group mean. None of the patients reported awareness during a standardized interview. Interestingly, propofol-remifentanil anesthesia blunted the release of epinephrine and cortisol to bypass surgery completely even when the propofol infusion rate was reduced according to BIS values.
  
  
  CONCLUSIONS
  Total intravenous anesthesia using propofol-remifentanil effectively attenuates the neurohumoral stress response to coronary bypass surgery involving cardiopulmonary bypass. Titration of propofol using BIS allows for significant reduction of propofol consumption, with only minor effects on stress response under these conditions.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Friedrich-Schiller-University, Jena, Germany. michael.bauer@med.uni-jena.de
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Wilhelm
authors.forename: Thomas
authors.initials: T
authors.lastname: Kraemer
authors.forename: Sascha
authors.initials: S
authors.lastname: Kreuer
authors.forename: Andreas
authors.initials: A
authors.lastname: Brandt
authors.forename: Hans Anton
authors.initials: HA
authors.lastname: Adams
authors.forename: Gudrun
authors.initials: G
authors.lastname: Hoff
authors.forename: Reinhard
authors.initials: R
authors.lastname: Larsen
mesh_terms: D000368:Aged; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000097:blood; D002315:Cardiopulmonary Bypass; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D004837:Epinephrine / Q000097:blood; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007262:Infusions, Intravenous; D016753:Interleukin-10 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009638:Norepinephrine / Q000097:blood; D010880:Piperidines / Q000008:administration & dosage; D015742:Propofol / Q000008:administration & dosage / Q000097:blood; D011446:Prospective Studies; D000077208:Remifentanil; D013312:Stress, Physiological / Q000097:blood / Q000503:physiopathology*
chemical_list: D018686:Anesthetics, Intravenous; D015850:Interleukin-6; D010880:Piperidines; D016753:Interleukin-10; D000077208:Remifentanil; D006854:Hydrocortisone; D009638:Norepinephrine; D015742:Propofol; D004837:Epinephrine