title: Cerebral ischaemia during cardiac surgery in children detected by combined monitoring of BIS and near-infrared spectroscopy.
abstract: BACKGROUND
  Children frequently suffer transient cerebral ischaemia during cardiac surgery. We measured cerebral ischaemia in children during cardiac surgery by combining two methods of monitoring.
  
  
  METHODS
  We studied 65 children aged between 5 months and 17 yr having surgery to correct non-cyanotic heart disease using hypothermic cardiopulmonary bypass (CPB). During surgery, we measured the Bispectral Index (BIS) and regional cerebral haemoglobin oxygen saturation (SrO2) with near-infrared spectroscopy (NIRS). Cerebral ischaemia was diagnosed if both SrO2 and BIS decreased abruptly when acute hypotension occurred. In each patient, the relationship between SrO2 and arterial blood pressure (AP) was indicated by a plot of mean SrO2 against simultaneous mean AP.
  
  
  RESULTS
  We noted 72 episodes of cerebral ischaemia in 38 patients. Sixty-three ischaemic events were during CPB. Cerebral ischaemia was less frequent in older patients. Cerebral ischaemia was more common and more frequent in children under 4 yr old. Haematocrit during CPB was lower and SrO2 was more dependent on AP in children under 4 yr.
  
  
  CONCLUSIONS
  Children less than 4 yr of age are more likely to have cerebral ischaemia caused by hypotension during cardiac surgery. Ineffective cerebral autoregulation and haemodilution during CPB may be responsible.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. hayashida-todai@umin.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Hayashida
authors.forename: N
authors.initials: N
authors.lastname: Kin
authors.forename: T
authors.initials: T
authors.lastname: Tomioka
authors.forename: R
authors.initials: R
authors.lastname: Orii
authors.forename: H
authors.initials: H
authors.lastname: Sekiyama
authors.forename: H
authors.initials: H
authors.lastname: Usui
authors.forename: M
authors.initials: M
authors.lastname: Chinzei
authors.forename: K
authors.initials: K
authors.lastname: Hanaoka
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology; D002315:Cardiopulmonary Bypass; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007022:Hypotension / Q000150:complications; D007223:Infant; D007431:Intraoperative Complications / Q000175:diagnosis*; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D012307:Risk Factors; D019265:Spectroscopy, Near-Infrared / Q000379:methods