Bispectral Index Monitoring Improves the Cognitive Function after Desflurane –Anaesthesia in Elderly Patients Undergoing Spine Surgery

Postoperative cognitive dysfunction is a common complication in the elderly patients receiving desflurane anaesthesia. The bispectral index score (BIS) -targeted desflurane anaesthesia may hasten the recovery and cognitive function in the elderly patients after spine surgery. Forty patients aged >60 yr., scheduled for elective spine surgery were randomly allocated to BIS targeted (n=20) and MAC targeted (n=20) groups. Perioperative changes in the end-tidal (ET) concentrations of desflurane, times to emergences from anaesthesia and extubation, Aldrete score, cortisol and norepinephrine and the Mini Mental State Examination (MMSE) for the first 3 postoperative days were recorded. Perioperative changes in heart rate and mean arterial blood pressure were similar in both groups. The patients in the BIS targeted group showed significantly lower ET concentrations of desflurane, shorter times to eye opening, to follow commands and to tracheal extubation and higher Aldrete score and 24-hour MMSE values compared with those in the minimum alveolar concentration (MAC) targeted group (p<.05). Perioperative cortisol and norepinephrine plasma levels were similar in both groups. It was concluded that BIS-targeted desflurane anaesthesia provides faster recovery and improves the cognitive function in the elderly patients after spine surgery.