title: Ketamine has no effect on bispectral index during stable propofol-remifentanil anaesthesia.
abstract: BACKGROUND
  Ketamine 0.15-1 mg kg(-1) decreases postoperative morphine consumption, but 0.5 mg kg(-1) is associated with an increase in the bispectral index (BIS) values that can lead to an overdose of hypnotic agents. The purpose of our investigation was to study the effect of ketamine 0.2 mg kg(-1) administered over a 5 min period on the BIS during stable target-controlled infusion (TCI) propofol-remifentanil general anaesthesia.
  
  
  METHODS
  Thirty ASA I or II patients undergoing abdominal laparoscopic surgery were included in this double-blind, randomized study. Anaesthesia was induced and maintained with a TCI of propofol and remifentanil. After 5 min of steady-state anaesthesia (BIS at 40) without surgical stimulation, patients received either an infusion of ketamine 0.2 mg kg(-1) or normal saline. The test drug was infused over 5 min. Standard parameters and BIS values were recorded every minute until 15 min post-infusion.
  
  
  RESULTS
  The baseline mean (sd) value for the BIS was 37 (6.5) for the ketamine group and 39 (8.2) for the placebo group. The highest mean BIS value during the recording period was 41.5 (8.7) for the ketamine group and 40.1 (8.9) for the placebo group. BIS values were not statistically different between the groups (P=0.62); there was no significant change over time (P=0.65) with no group-time interaction (P=0.55).
  
  
  CONCLUSIONS
  Under stable propofol and remifentanil TCI anaesthesia, a slow bolus infusion of ketamine 0.2 mg kg(-1) administered over a 5 min period did not increase the BIS value over the next 15 min.
authors.affiliation: CUB Erasmus Hospital, University Department of Anaesthesia-Reanimation, Route de Lennik, 808, Brussels, Belgium. david.faraoni@ulb.ac.be
authors.forename: D
authors.initials: D
authors.lastname: Faraoni
authors.forename: J-C
authors.initials: JC
authors.lastname: Salengros
authors.forename: E
authors.initials: E
authors.lastname: Engelman
authors.forename: B
authors.initials: B
authors.lastname: Ickx
authors.forename: L
authors.initials: L
authors.lastname: Barvais
mesh_terms: D000328:Adult; D000368:Aged; D000700:Analgesics / Q000494:pharmacology*; D019162:Anesthetics, Combined / Q000494:pharmacology*; D000778:Anesthetics, Dissociative / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D004311:Double-Blind Method; D004347:Drug Interactions; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006801:Humans; D007649:Ketamine / Q000494:pharmacology*; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010149:Postoperative Pain / Q000517:prevention & control; D010880:Piperidines / Q000494:pharmacology; D015742:Propofol / Q000494:pharmacology; D000077208:Remifentanil; D055815:Young Adult
chemical_list: D000700:Analgesics; D019162:Anesthetics, Combined; D000778:Anesthetics, Dissociative; D018686:Anesthetics, Intravenous; D010880:Piperidines; D007649:Ketamine; D000077208:Remifentanil; D015742:Propofol