Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Observational
Official Title: Determine the Effective Dose 95 of Sevoflurane in Adult Patients Undergoing Cardiac Surgery Under Cardiopulmonary Bypass.
Brief Summary:
Introduction: Sevoflurane is the most volatile anesthetic used during CPB. In addition to the cardioprotective effect, Sevoflurane also promotes reduction in systemic vascular resistance and also an important role in anesthesia maintenance during surgery, preventing patients awaken in the intraoperative. 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.
Aims: 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.
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.