[Effects of phenobarbital on EEG and sensory evoked potentials in normal cat brain]

In adult cats, authors studied changes in parameters obtained by the recordings of sensory evoked potentials following cumulative intravenous administration of phenobarbital. P1 and N1 of cortical SEP showed gradual tendencies to decrease in amplitude and to increase in latency with increasing barbiturate dose. These changes preceded to the appearance of burst-suppression activity on electroencephalogram. At this point I-II and III-IV interpeak latencies of BAEP showed statistically significant increase. BAEP and all early components of SEP (I.II.III) persisted in the extremely high serum concentration of phenobarbital. Furthermore, II-III interpeak latency of BAEP showed no statistically significant increase. These experimental results suggest that sensory evoked potentials will provide useful information in the assessment of the brainstem function in patients under deep coma.