Bilateral Bispectral Index (BIS)-Monitoring in Cardiac Surgery Patients

The bispectral index (BIS) is derived from a single-channel electroencephalogram (EEG) and provides information on the anaesthetic depth. Recently, a bilateral two-channel EEG-sensor has been introduced to monitor the BIS on both cerebral hemispheres. In some patients significant left-right differences may occur, whereas no relevant side differences are expected in the majority of patients. The aim of this study is to * investigate the incidence, duration and degree of left-right BIS differences * examine the relation between BIS differences and occurrence of cognitive deficits