The use of aperiodic analysis of the EEG during carotid artery surgery.

A new processed EEG machine, the Lifescan, which uses aperiodic analysis, was used to monitor cerebral activity prospectively in twenty-one patients undergoing carotid artery surgery under general anaesthesia. The machine was easy to apply, use and read. Volatile agents caused a bilateral decrease in high frequency activity. Unilateral changes consistent with cerebral ischaemia at the time of carotid cross-clamping were also seen. One such prolonged change was not associated with neurological deficit. A further patient awoke with neurological deficit without displaying Lifescan evidence of ischaemia. The machine requires further assessment.