title: Closed-loop control of anesthesia using the bispectral index in open heart surgery.
abstract: OBJECTIVE
  The introduction of the bispectral index (BIS) as a comprehensive indicator of depth of anesthesia has prompted research in the automated delivery of anesthetics. This trial aimed to evaluate the usefulness of the BIS as the feedback variable in a closed-loop anesthesia control system during cardiac surgery under cardiopulmonary bypass (CPB).
  
  
  METHODS
  Thirty-four adult patients of American Society of Anesthesiologists grade I-III undergoing elective cardiac surgery under hypothermic CPB were evaluated prospectively in a tertiary care teaching hospital. The anesthesia was induced and maintained throughout surgery using a closed-loop anesthesia delivery system (502/DEL/2003) to control the BIS.
  
  
  RESULTS
  The closed-loop system was functional during 96% of the anesthesia duration. The BIS was maintained at +/- 10 of the target of 50 during 86% of the automated anesthesia. The closed-loop system was also functional during CPB despite a fall in BIS probably resulting from hypothermia. None of the patients had recall of events or experiences during the procedure.
  
  
  CONCLUSIONS
  The closed-loop control of anesthetic delivery adjusted to BIS is feasible and may be useful in open heart surgery under hypothermic CPB.
authors.affiliation: Department of Anesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India. gdpuri007@hotmail.com
authors.forename: Govardhan Dutt
authors.initials: GD
authors.lastname: Puri
authors.forename: Preethy Joseph
authors.initials: PJ
authors.lastname: Mathew
mesh_terms: D000328:Adult; D000764:Anesthesia, Closed-Circuit; D001794:Blood Pressure; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged