Introduction Some studies showed evidence of cardio-protection and reduction in mortality due to the use of volatile agents during cardiac surgery. (1) These findings seems to be associated when the volatile agents are used during all the surgical procedure, including the period of CPB. (2) Sevoflurane is the most volatile anesthetic used during CPB. In addition to the cardioprotective effect, Sevoflurane also promotes reduction in systemic vascular resistance (4.5) and also an important role in anesthesia maintenance during surgery, preventing patients awaken in the intraoperative (6.7). To avoid the awakening during surgery, assessment of the level of consciousness through the bispectral index (BIS) has been the most common method used by anesthesiologists. During cardiac surgery the most critical moment may be the patient is awaken during the warm up phase of CPB. The monitoring of this phase with the BIS has become efficient as to alert the anesthetist that the patient may be waking up. (3) In addition, several studies have been trying to find what is the ideal minimum dose of inhaled anesthetics that 95% of patients do not awaken during some surgical procedures (ED 95). (8-25). However, there are no studies that demonstrate what is the ideal minimum dose of inhaled anesthetics used during CPB in cardiac surgery, so patients do not have any conscience at this stage. Case we have this information, even when it is not possible to monitor the level of consciousness using the BIS, the risk for patients to awaken during the intraoperative period, especially the CEC, would become significantly reduced.