Evaluation of Continuous Electroencephalogram Recording for Assessing and Control of Depth of Anesthesia in Elderly Patients

The Bispectral Index (BIS) is a neurophysiologic monitoring system، which continuously analyzes the electroencephalogram recording of a patient during general anesthesia to assess the patient''s level of consciousness. When one is awake، the brain cortex is very active، with marked EEG signals. However، during sleep or under general anesthesia، the signal patterns change. This is used as a method for determining depth of anesthesia in patient، in order to facilitate their awakening and discharge from the recovery room. The aim of this study was to evaluate the effect of BIS monitoring on control of the depth of anesthesia for accelerating the awakening process and minimizing the recovery time in elderly patients. In this clinical trial، 68 patients (over the age of 60) participated who had the American Society of Anesthesiologists physical status of I or III and were scheduled for elective abdominal surgery. The patients were randomly allocated to two groups either receiving general anesthesia with BIS monitoring or without it. Data were compared between groups by using the Kaplan-Meier Tests. The time to orientation was faster in the BIS group compared to the control group. There were significant differences regarding the post-operative orientation time between the two groups (P =0. 0001). Both the recovery time and discharge from recovery were significantly faster in the BIS group compared with the control group.