A rapid increase in the inspired concentration of desflurane is not associated with epileptiform encephalogram.

UNLABELLED: The large inspired concentration of sevoflurane (S) during mask induction of anesthesia can induce epileptiform electroencephalogram (EEG) associated with tachycardia. Tachycardia is also seen when the concentration of desflurane (D) is abruptly increased. It is not known whether this is associated with epileptiform EEG similar to S. We studied EEG and heart rate (HR) during rapidly increased concentrations of S or D in 31 females during the postintubation period of anesthesia. Anesthesia was induced with propofol and remifentanil, and the tracheas were intubated. Patients were randomized to receive either S or D in nitrous oxide-oxygen mixture after intubation, at a small dose first. After 10 min, S or D vaporizer was advanced to the highest reading of the vaporizer (7% for S, 18% for D) for 5 min. HR and EEG were recorded. Epileptiform EEG activity was recorded in eight of 15 patients in group S and in none in group D (P < 0.05). HR increased in both groups. In group S, HR increased gradually and the highest HR value was 84 bpm at 5 min after the increase in sevoflurane concentration. In group D, HR increased to 93 bpm 2 min after the increase in desflurane concentration (no significant difference, S versus D). A rapid increase in the concentration of S frequently induces epileptiform EEG during normoventilation. Tachycardia during increasing concentrations of D is not associated with epileptiform EEG. IMPLICATIONS: A rapid increase in the concentration of sevoflurane induces epileptiform encephalogram (EEG) with tachycardia. A rapid increase in the concentration of desflurane also induces tachycardia but is not associated with epileptiform EEG.

Monitoring Seizure Duration During Electroconvulsive Therapy.

Three alternative monitoring methods for assessing the duration of seizures during electroconvulsive therapy were studied. The mean integrated amplitude of the electroencephalogram, facial muscle electromyogram, and "cuff method" were compared with the reference single-channel unprocessed electroencephalogram in 78 sessions with 17 patients. The measures of seizure duration differed significantly (p < 0.001). The mean integrated electroence phalographic amplitude differences were small and an artifact of the sampling procedure. Larger, but clinically unimportant, discrepancies were obtained with the facial electromyogram amplitude. In contrast, there were marked differences between the electroencephalogram and the "cuff method," which suggest that the latter technique may be of limited usefulness.