title: Differential electroencephalographic response to tracheal intubation between young and elderly during isoflurane and sevoflurane nitrous oxide anaesthesia.
abstract: BACKGROUND
  Age-associated differences in the electroencephalographic (EEG) response to noxious stimuli with the presence of nitrous oxide (N(2)O) are unknown. We compared the EEG response with tracheal intubation between young and elderly.
  
  
  METHODS
  Sixty young (<40 yr) and elderly (>70 yr) patients were randomly allocated to one of the four groups. Anaesthesia was induced with 66% N(2)O and isoflurane in oxygen (Young-isoflurane and Elderly-isoflurane groups) or 66% N(2)O and sevoflurane in oxygen (Young-sevoflurane and Elderly-sevoflurane groups). Inhaled isoflurane and sevoflurane concentrations were gradually increased and the end-tidal concentrations were maintained at 1.1% and 1.7%, respectively. Tracheal intubation was performed 12 min after induction of anaesthesia.
  
  
  RESULTS
  There were significant differences in the overall changes in bispectral index (BIS) and 95% spectral edge frequency (SEF95) between young and elderly (P<0.001 for both), but not between patients receiving isoflurane and sevoflurane (P=0.4 and 0.3, respectively). Both BIS and SEF95 were significantly decreased after tracheal intubation in Young-isoflurane and Young-sevoflurane groups (P<0.05 for all). In sharp contrast, BIS and SEF95 remained unchanged in Elderly-isoflurane and Elderly-sevoflurane groups (P>0.7 for all). These results suggest that both BIS and SEF95 significantly decreased, despite the presence of increased sympathetic activity after tracheal intubation in young patients.
  
  
  CONCLUSIONS
  A significant difference was detected in EEG response to tracheal intubation between young and elderly. BIS does not reflect the depth of anaesthesia after tracheal intubation during anaesthesia with isoflurane or sevoflurane with 66% of N(2)O in young patients.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Graduate School of Medicine, Osaka City University, 1-5-7 Asahimachi, Abeno-ku, Osaka 545-8586, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Matsuura
authors.forename: Y
authors.initials: Y
authors.lastname: Oda
authors.forename: K
authors.initials: K
authors.lastname: Ikeshita
authors.forename: K
authors.initials: K
authors.lastname: Nishikawa
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: A
authors.initials: A
authors.lastname: Asada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D019162:Anesthetics, Combined / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007442:Intubation, Intratracheal; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology; D016343:Monitoring, Intraoperative / Q000379:methods*; D009609:Nitrous Oxide / Q000494:pharmacology; D000077149:Sevoflurane
chemical_list: D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane; D009609:Nitrous Oxide