The Use of the Time Domain Analyzed EEG in Conjunction with Cardiovascular Parameters for Monitoring Anesthetic Levels

A simple time domain method of EEG analysis based upon the computation of the frequency and the amplitude of the zeroth, first, and second derivative of the EEG wave has been developed for monitoring the anesthetic level of patients undergoing general anesthesia. This study explores the effectiveness of this EEG analytical system working in conjunction with cardiovascular parameters in discriminating among commonly used anesthetic dosages. EEG features and cardiovascular features were used as variables in a stepwise discriminant analysis on two patient group sets each using a light, medium, and deep dosage level of the agents halothane/nitrous oxide and enflurane/nitrous oxide, respectively. The best overall discriminant prediction of the three 30-patient groups using halothane and nitrous oxide was 86.7 percent correct. The best overall discriminant prediction of the three 30-patient groups using enflurane and nitrous oxide was 90 percent correct. It was felt that these accuracies were sufficient to continue development of this sytem, the next step being the determination of a suitable anesthetic depth scale based upon the use of these and perhaps additional physiological features.