Correlation of instantaneous heart rate and EEG suppression during enflurane anaesthesia: synchronous inhibition of heart rate and cortical electrical activity?

EEG burst suppression and instantaneous heart rate were studied during enflurane anaesthesia in 15 patients. Heart rate increased at EEG burst onset and decreased at suppression onset. Short epileptic discharges accompanied by an increase in heart rate were seen in 2 patients. We suggest that suppressions in EEG may be caused by active inhibition, with synchronous decrease of heart rate.