Intervention
Patients were randomly allocated to two groups: deep and shallow anesthesia, at the completion of the operation. The effect-site concentration (Ce) of propofol were adjusted to maintain BIS values between 25 − 35 in the deep and 45 − 55 in the shallow anesthesia group for 10 min of the “stabilization period.” The Ce of remifentanil was fixed at 2 ng mL