title: Bispectral index values and propofol concentrations at loss and return of consciousness in patients with frontal brain tumours and control patients.
abstract: BACKGROUND
  The influence of frontal brain tumours on bispectral index (BIS) measurements and propofol requirements is unknown. The primary aim of our study was to determine whether BIS values recorded at loss and return of consciousness (LOC and ROC, respectively) differ between patients with unilateral frontal brain tumours and control patients. Secondary goals were to compare propofol requirements for LOC and to determine whether there were significant inter-hemispheric differences between BIS values in tumour and control patients.
  
  
  METHODS
  We enrolled 20 patients with a frontal brain tumour and 20 control patients. Bilateral BIS measurements were done during induction of propofol anaesthesia, during recovery of consciousness, and during a second induction of anaesthesia. The isolated-forearm test was used to determine the moments of LOC1, ROC, and LOC2. Arterial blood samples were obtained every 4 min for determination of measured propofol concentrations.
  
  
  RESULTS
  The median BIS values recorded at LOC1, ROC, and LOC2 did not differ between the groups. There were no significant inter-hemispheric differences in BIS in tumour and control patients. The median [inter-quartile range (IQR)] total propofol doses at LOC1 were 82 (75-92) and 78 (68-91) mg in tumour and control patients, respectively. The median (IQR) measured plasma propofol concentrations at LOC1 were 12 (9-14) and 13 (11-15) µg ml(-1) in the tumour and control groups, respectively.
  
  
  CONCLUSIONS
  The presence of a frontal brain tumour did not affect ipsilateral BIS values, and so need not influence the placement of unilateral BIS electrodes if BIS monitoring is used to titrate propofol anaesthesia.
authors.affiliation: Department of Anesthesiology,.
authors.forename: M M
authors.initials: MM
authors.lastname: Sahinovic
authors.forename: U
authors.initials: U
authors.lastname: Beese
authors.forename: E H
authors.initials: EH
authors.lastname: Heeremans
authors.forename: A
authors.initials: A
authors.lastname: Kalmar
authors.forename: K
authors.initials: K
authors.lastname: van Amsterdam
authors.forename: R J H M
authors.initials: RJ
authors.lastname: Steenbakkers
authors.forename: H
authors.initials: H
authors.lastname: Kuiper
authors.forename: R
authors.initials: R
authors.lastname: Spanjersberg
authors.forename: R J M
authors.initials: RJ
authors.lastname: Groen
authors.forename: M M R F
authors.initials: MM
authors.lastname: Struys
authors.forename: A R
authors.initials: AR
authors.lastname: Absalom
mesh_terms: D000328:Adult; D000368:Aged; D018686:Anesthetics, Intravenous / Q000097:blood*; D001932:Brain Neoplasms / Q000503:physiopathology* / Q000601:surgery; D003243:Consciousness / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000097:blood*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol
keywords: brain tumour; depth of anaesthesia; monitoring, bispectral index; pharmacology, propofol