[Early detection of central nervous system dysfunction during cardiopulmonary bypass using EEG monitoring]

The EEG was monitored in fifty-four patients during and after various surgeries requiring cardiopulmonary bypass (CPB) to assist in the early detection of central nervous system dysfunction (CNSD). Bilateral frontopolar EEG signals were processed with a 2-channel, real-time Fast-Fourier-Transformer (FFT) analyser and Compressed Spectral Arrays (CSA) were obtained. The fifty-four patients were divided into 3 groups based upon clinical outcome; Group 1: patients without CNSD (83%); Group 2: patients with delayed recovery from anesthesia but without CNSD (4%); and Group 3: patients with apparent postoperative CNSD (13%). There was no difference in the CSA among these groups prior to rewarming, but after the rewarming phase, two distinct sets emerged. Groups 1 and 2 showed a shift of the CSA predominant peak from a low frequency to a higher frequency. On the other hand, Group 3 patients demonstrated either stable predominant peaks in the lower frequencies or gradual flattening of the CSA. We conclude that the intra-operative EEG monitoring is a useful tool for the early detection of CNSD during and after CPB.