POWER SPECTRAL-ANALYSIS OF THE ELECTROENCEPHALOGRAM DURING INCREASINGEND-EXPIRATORY CONCENTRATIONS OF ISOFLURANE, DESFLURANE AND SEVOFLURANE

We studied the effects of increasing end-expiratory concentrations of isoflurane (0.3, 0.6, 0.9, 1.2 vol.%) (n = 12 patients), desflurane (1 .5, 3.0, 4.5, 6.0 vol.%) (n = 12 patients) and sevoflurane (0.5, 1.0, 1.5, 2.0 vol.%) (n = 12 patients) on power spectral analysis of the el ectroencephalogram (EEG). Spectral edge frequency (SEF), total power ( TP) and relative power in the delta, theta, alpha and beta band were c alculated. EEG changes were very similar within the three groups. SEF decreased, TP and relative power in the delta and theta band increased , power in the beta band decreased in a dose-dependent fashion with co mparable regression lines. This indicates that MAC equivalent administ ration of isoflurane, desflurane and sevoflurane in clinically applied dose ranges is associated with equipotent EEG suppression.