EXCITATORY EFFECTS AND ELECTROENCEPHALOGRAPHIC CORRELATION OF ETOMIDATE, THIOPENTAL, METHOHEXITAL, AND PROPOFOL

Excitatory movements have been observed during induction of anesthesia with etomidate, thiopental, methohexital, and propofol. We studied th e frequency of these excitatory effects and correlated movements with electroencephalographic (EEG) findings in 67 unpremedicated patients ( mean age 66.1 yr, range 45-82 yr). Excitatory effects, including myocl onus, tremor, and dystonic posturing, occurred in 86.6% of patients re ceiving etomidate; 69.2% of the patient responses were myoclonic. Mult iple spikes appeared on the EEG in 22.2% of the etomidate patients. Th e frequency of excitatory effects was 16.6% after thiopental, 12.5% af ter methohexital, and 5.5% after propofol. None of the patients receiv ing thiopental, methohexital, or propofol developed myoclonic or seizu re activity. In most patients, the excitatory movements were coinciden t with the early slow phase of the EEG which corresponds to the beginn ing of deep anesthesia. We conclude that perhaps caution should be exe rcised when administering etomidate to patients with a history of seiz ures as the myoclonic activity is associated with seizure activity. Th e incidence of excitatory movements after administration of propofol i s very low.