Comparison of spectral entropy and bispectral index electroencephalography in coronary artery bypass graft surgery.
OBJECTIVE
The study's aim was to compare response entropy (RE) and state entropy (SE) with bispectral index (BIS) electroencephalography (EEG) as an alternative cerebral monitoring tool in patients scheduled for coronary artery bypass graft surgery.


METHODS
Prospective, observational single-center study.


METHODS
University hospital.


METHODS
Thirty patients undergoing coronary artery bypass graft surgery receiving remifentanil-propofol anesthesia.


METHODS
Surgery was performed with cardiopulmonary bypass (CPB) and cardiac arrest in 15 patients, with CPB without cardiac arrest in 9 patients and without CPB in 6 patients.


RESULTS
RE, SE, BIS, burst suppression ratio (BSR), and frontal electromyography (f-EMG) were detected simultaneously. RE and SE compared favorably with BIS and their correlations were strong (r(2) = 0.6, r(2) = 0.55, respectively). The mean bias of RE and BIS was -1.8, but limits of agreement were high (+20.5/-24.1). RE and SE tended to be lower than the BIS values in the CPB subgroups. The detection of BSR was similar with RE and SE and the BIS. A strong correlation existed between BIS and f-EMG (r(2) = 0.62) in contrast to RE (r(2) = 0.45) and SE (r(2) =0.39). BIS monitoring was significantly more disturbed than RE and SE with 9.1% +/-10.9% and 0.1% +/- 0.2% of the total anesthesia time, respectively. Neither implicit nor explicit memory was shown.


CONCLUSIONS
RE and SE are comparable with the BIS but showed significantly less interference from f-EMG and superior resistance against artifacts. Thus, spectral entropy is more suitable than the BIS during propofol-remifentanil anesthesia in cardiac surgery patients.
Baulig
Werner
W
Division of Cardiac Anaesthesia, University Hospital Zurich, Zurich, Switzerland. werner.baulig@usz.ch
Seifert
Burkhardt
B
Schmid
Edith R
ER
Schwarz
Urs
U
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000771:Anesthesia, Intravenous / Q000295:instrumentation / Q000379:methods / Q000592:standards; D056805:Consciousness Monitors / Q000592:standards*; D001026:Coronary Artery Bypass / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies