Electroencephalographic study of the short-acting hypnotics etomidate and methohexital in dogs.
Beagles, implanted with cortical and subcortical electrodes, were given etomidate i.v. (1 mg/kg) over a period of 10 sec. The effects on the EEG were compared with those obtained with 7 mg/kg of methohexital. Both compounds induced hypnosis for a duration of approximately 8 min. The EEGs showed a remarkable similarity. Visual inspection of the records as well as power spectrum analysis revealed a sustained theta-activity with underlying fast activity. The configuration of the waves was rather sharp. The power obtained after etomidate was, however, 2 to 3 times that obtained after methohexital. When the animals awoke from etomidate-induced hypnosis slow waves appeared and were followed by alpha-activity, whereas after methohexital-hypnosis beta-activity predominated. Etomidate slightly increased heart rate, but respiratory depression was not observed. Methohexital caused pronounced tachycardia and apnoea. In 3 out of 6 dogs methohexital caused myoclonus of the hind legs upon awakening from anaesthesia. Etomidate induced myoclonus in one dog during hypnosis.
D000818:Animals; D004285:Dogs; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D005045:Etomidate / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D008723:Methohexital / Q000494:pharmacology*; D013997:Time Factors
D007093:Imidazoles; D008723:Methohexital; D005045:Etomidate