Closed-loop control of anesthesia using the bispectral index in open heart surgery.
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.
Puri
Govardhan Dutt
GD
Department of Anesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India. gdpuri007@hotmail.com
Mathew
Preethy Joseph
PJ
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