During CPB, including the rewarming phase of the patient (normothermia time - temperature ranging from 36 to 37.5 ° C), end tidal sevoflurane concentration will be maintained in accordance with the preview-set value by Up-and-Down method Dixon studied for each patient. During this period will be evaluated BIS value constantly. During CPB, no intravenous anesthetic drug will be used until it is needed with the BIS values ≥ 50 for a period ≥ 1 minute.