title: Changes in BiSpecteral Index (BiS) Values During Cardiopulmonary Bypass (CPB).
abstract: BACKGROUND
  BiSpecteral Index (BiS) monitoring is standard monitoring regimen in anaesthesia practice. It has also been used in cardiac surgery. It is especially important due to the high incidence of neurological injury or dysfunction that occurs following CPB. This is a retrospective study of 33 cases that were monitored with BiS during the course of coronary artery or valvular surgery, including the period of CPB.
  
  
  METHODS
  Thirty three cases monitored with BiS were studied retrospectively.
  
  
  RESULTS
  From the recordings it was determined that the value of BiS which was ranging between 40 to 60 after induction, dropped below 25 at the onset of CPB. This change was statistically significant (p<0.05).
  
  
  CONCLUSIONS
  This decrease in the BiS value is probably a result of hypo-perfusion and due to clear, oxygen - poor priming fluid reaching the brain. Other periods of hypotension also correlated with the low values of BiS. This cerebral hypoxia which would occur at this time could be the cause of the incidence of neurological dysfunction that is known to occur following CPB.
authors.affiliation: Senior Advisor (Anaesthesiology), MH (CTC), Pune-40.
authors.forename: Ashok
authors.initials: A
authors.lastname: Sinha
authors.affiliation: Consultant (Anaesthesiology), Army Hospital (R&R), Delhi Cantt.
authors.forename: G S
authors.initials: GS
authors.lastname: Ramesh
authors.affiliation: Brig Med, HQ Bengal Area, Alipore, Kolkata-27.
authors.forename: V P
authors.initials: VP
authors.lastname: Singh
keywords: BiSpectral Index; Cardiac surgery; Monitoring; Neurological dysfunction