EEG data during open heart surgery. Their automatic analysis related to anesthetic parameters and its use in peroperative monitoring of cerebral function

It is generally agreed upon by experts that EEG monitoring of brain function during open heart surgery is of the utmost importance in preventing postoperative neurological and psychopathological consequences. Up to now, however, this monitoring has not been performed on a large scale: (1) it is a very time-consuming task for the clinical neurophysiologist; (2) the anesthetist does not generally possess enough knowledge of this part of neurophysiology to get more than only a rough impression of the alterations of brain function during these procedures. To improve this situation we developed an automatic method to monitor brain function: the results of period-amplitude analysis of the EEG are continuously related to a number of important parameters — blood pressure, temperature, anesthesia. The way this is done resembles to a large degree the procedure which the neurophysiologist uses to judge the EEG during monitoring. The system generates warning and alerting signals, which also indicate the kind of disturbance when a marginal situation occurs. The anesthetist may take measures within 1 min to restore the condition. This is in complete agreement with the needs of anesthesiology. By means of a special function keyboard the anesthetist uses the system interactively and introduces all the necessary information which is needed for the proper functioning of the warning system (kind and quantity of different anesthetics and other drugs). At the end of the procedure the total information about the EEG, patient parameters and anesthetic measures are plotted in graphical form and printed as a table for documentation purposes which to a large degree may do away with the usual documentation. The introduction of this automatic monitoring system opens the way to a large scale use of EEG monitoring during open heart surgery