Methodology: Dixon's up-and-down technique is a commonly used method to define MAC (27-30). The anesthetic concentration applied to the first patient is estimated by clinical experience. If there BIS values below 50, the concentration of inhalational anesthetic in subsequent patient is decreased by 20%. If the BIS show values greater than or equal to 50 for a period ≥ 1 minute steadily, the concentration is increased by 20% in the next patient. In each series of patients, the pairs of independent cross in order measurements are identified. Logistic regression is used 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.