Anesthesia and patient monitoring
Standard monitoring, including pulse oximetry, three-lead electrocardiography, and noninvasive blood pressure measurements, was performed. A BIS sensor (BIS Quatro™; Medtronic, Dublin, Ireland) was attached to the forehead and connected to BIS monitor (BIS complete monitoring system; Medtronic, Dublin, Ireland) according to the manufacturer’s instructions as we described elsewhereAfter the trachea was extubated, the patients were transferred to the post anesthesia care unit. The patients were interviewed using a modified version of the Brice questionnaire for intraoperative recall after returning to a fully alert status