The primary endpoint of this study is to determine the ideal minimum dose of sevoflurane (ED 95) that 95% of patients undergoing anesthesia during CPB in cardiac surgery have no intraoperative awareness. Secondary endpoints include neurocognitive assessment using the Mini Mental Test; Intraoperative assessment of memory; time of endotracheal intubation (OTI); length of stay in intensive care unit (ICU); and hospital stay.