[Monitoring of electroencephalogram during the operation under the extracorporeal circulation]

Generally speaking, it is difficult to know the occurrence of brain complication until the patient becomes awake from anesthesia. But if we can detect the occurrence of of brain complication during the operation, we can start its therapy even during the operation. In order to detect the occurrence of brain complication during the operation under extracorporeal circulation (ECC), we monitored intraoperative electroencephalogram (EEG). Since June 1992, forty-two patients were operated on using ECC. Usual ECC was applied in 39 cases (Group-A), and circulatory arrest with retrograde cerebral perfusion was applied in remaining three cases (Group-B). We studied the amplitude of EEG using actual value (by Fujimori method), and compressed EEG acquired by slow-paper-feed recording. In terms of the frequency of EEG, we studied compressed spectral array (CSA). In Group-A, there was no brain complication identified after operation. Actual values of amplitude were 23 +/- 4.0 microV (before ECC), 19 +/- 4.0 microV (during ECC), 23 +/- 4.9 microV (after ECC). There was a significant decrease (p < 0.001) of amplitude during ECC compared with that before ECC. The ratio of amplitude during ECC to that before ECC (D/B ratio) was 0.82 +/- 0.16. The ratio of amplitude after ECC to that before ECC (A/B ratio) was 1.01 +/- 0.15. According to compressed EEG, it was observed that the amplitude changes following the up-down of esophageal temperature. In CSA, influence of esophageal temperature on the power spectrum of alpha and delta wave band was recognized. In Group-B, there was one brain complication identified after operation.(ABSTRACT TRUNCATED AT 250 WORDS)