Prognostic value of electroencephalography in cardiac surgery

One hundred seventeen patients undergoing cardiac operations over a two-year period were studied. Electroencephalograms were recorded preoperatively, in the recovery room (up to 12 hours following operation), 24 hours later, and further as required. Operative and anesthesia data were correlated with EEG findings. All patients had normal EEGs preoperatively. This unusual occurrence may largely reflect the absence of congenital heart disease and the small number of valvular lesions in our patients. Prognosis was not significantly influenced by age. Bypass time appeared directly related to outcome by group but not individually. Hypotension prior to pumping occurred most often and mean blood loss was greatest in the patients who had abnormal EEGs in the recovery room with progressively worsening patterns until death. In the recovery room many patients were awake, while others were either drowsy, lethargic, or asleep. Some were comatose. The level of consciousness was not as prognostic as was the EEG. The pattern of EEGs in the first few postoperative days is more important than any single record by itself. All those who showed progressive deterioration in the first two or three days died shortly thereafter.