“…Although high-dose fentanyl anesthesia produces hemodynamic stability, intraoperative awareness and postoperative prolonged respiratory depression sometimes occur [2][3][4]. Therefore, to solve these problems, balanced anesthetic techniques, such as the combination of moderate doses of fentanyl with halogenated agents [5], benzodiazepines [6], or propofol [7,8], have been common for cardiac surgery.…”