title: Effects of deep hypothermic circulatory arrest with retrograde cerebral perfusion on electroencephalographic bispectral index and suppression ratio.
abstract: OBJECTIVE
  No systematic study has been conducted to investigate effects of deep hypothermic circulatory arrest (DHCA) on electroencephalographic bispectral index (BIS) and suppression ratio (SR). Thus, the effects of DHCA were evaluated on BIS and SR.
  
  
  METHODS
  A prospective clinical study.
  
  
  METHODS
  University hospital (single institute).
  
  
  METHODS
  Twenty consecutive patients undergoing thoracic aortic surgery using DHCA under narcotics-sevoflurane anesthesia.
  
  
  METHODS
  BIS and SR were monitored during cardiopulmonary bypass, simultaneously with nasopharyngeal temperature (NPT).
  
  
  RESULTS
  BIS decreased to 0 with induction of deep hypothermia and rose again with rewarming, although rates of BIS changes in response to cooling and rewarming varied widely among patients. Typically, BIS decreased slowly until NPT reached 26 degrees C during cooling and then it began to decrease rapidly and reached 0 at 17 degrees C, in inverse proportion to SR, which increased rapidly with deep hypothermia and reached 100% at 17 degrees C. When SR was 50% or more, BIS was determined by SR according to the expression: BIS = 50-SR/2. With rewarming, BIS rose again and returned to precooling baseline levels. Time to the beginning of the BIS recovery significantly correlated with duration of DHCA.
  
  
  CONCLUSIONS
  With induction of deep hypothermia, BIS decreased in a biphasic manner to 0 at rates varying among patients. With rewarming, BIS rose again at rates extremely widely varying among patients. The rate of BIS recovery was related to duration of DHCA. BIS may be capable of conveniently tracing suppression and recovery of a part of cerebral electrical activity before, during, and after DHCA.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. hayashida-todai@umin.ac.jp
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hayashida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekiyama
authors.forename: Ryo
authors.initials: R
authors.lastname: Orii
authors.forename: Mieko
authors.initials: M
authors.lastname: Chinzei
authors.forename: Makoto
authors.initials: M
authors.lastname: Ogawa
authors.forename: Hideko
authors.initials: H
authors.lastname: Arita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hanaoka
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Takamoto
mesh_terms: D000368:Aged; D018685:Anesthetics, Inhalation; D001013:Aorta, Thoracic / Q000601:surgery; D001831:Body Temperature; D002315:Cardiopulmonary Bypass / Q000379:methods; D002560:Cerebrovascular Circulation; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods; D008297:Male; D008738:Methyl Ethers; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009294:Narcotics; D010477:Perfusion / Q000379:methods*; D017694:Rewarming / Q000379:methods; D000077149:Sevoflurane; D013997:Time Factors
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D009294:Narcotics; D000077149:Sevoflurane