title: Cerebral state index vs. bispectral index during sevoflurane-nitrous oxide anaesthesia.
abstract: OBJECTIVE
  The cerebral state index (CSI) is a low-cost and compact electroencephalographic monitor alternative to the bispectral index (BIS). Although both indices are shown as the number between 0 and 100, owing to the different calculation algorithms, both indices might be different during anaesthesia. The present study was performed to compare the BIS and CSI during sevoflurane-nitrous oxide anaesthesia.
  
  
  METHODS
  Forty patients scheduled for abdominal surgery aged 30-70 years were enrolled. The electrodes of both the cerebral state monitor and BIS were attached simultaneously. Anaesthesia was induced with midazolam and fentanyl, and was maintained with sevoflurane with 50% nitrous oxide in oxygen and intermittent epidural mepivacaine. During surgery, end-tidal sevoflurane concentration was kept at 0.5, 1.0, and 1.5% for more than 10 min to measure CSI and BIS.
  
  
  RESULTS
  The duration of signal disturbance by electric cautery was 12.6 +/- 4.2 min in the BIS and 3.9 +/- 1.8 min in the cerebral state monitor (P < 0.05) for 9.5 +/- 4.3 min duration of electric cautery. The recovery time from disturbance by electric cautery was 37 +/- 12 s in the BIS and 4 +/- 2 s in the cerebral state monitor (P < 0.05). The absolute values of the BIS and CSI were not significantly different. Both BIS and CSI decreased significantly when end-tidal sevoflurane concentration increased from 0.5 to 1.0%, but did not significantly change when end-tidal sevoflurane concentration increased from 1.0 to 1.5%. The BIS and CSI correlated well. The Bland-Altman plot showed good agreement between the BIS and CSI.
  
  
  CONCLUSIONS
  During sevoflurane-nitrous oxide anaesthesia, the CSI was not significantly different from the BIS in the awake state and with sevoflurane concentration 0.5-1.5%.
authors.affiliation: Department of Anesthesiology, University of Tokyo, Tokyo, Japan. nishit-tky@umin.ac.jp
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nishiyama
mesh_terms: D000005:Abdomen / Q000601:surgery; D000759:Adjuvants, Anesthesia; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D004564:Electrocoagulation; D004569:Electroencephalography / Q000295:instrumentation*; D005260:Female; D005283:Fentanyl; D006801:Humans; D016014:Linear Models; D008297:Male; D008619:Mepivacaine; D008738:Methyl Ethers; D008874:Midazolam; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D009609:Nitrous Oxide; D000077149:Sevoflurane
chemical_list: D000759:Adjuvants, Anesthesia; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008738:Methyl Ethers; D000077149:Sevoflurane; D008619:Mepivacaine; D009609:Nitrous Oxide; D008874:Midazolam; D005283:Fentanyl