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Currently available anesthetic induction agents provide adequate hypnosis but are not ideal, particularly in the high risk patient (ASA class III-V), because most cause myocardial and/or respiratory depression and some have other important side effects. Etomidate was recently marketed as an intravenous anesthetic induction agent. It is a non-barbiturate hypnotic without analgesic properties that has less cardiovascular and respiratory depressant actions than sodium thiopental, even in patients with minimal cardiovascular reserve. Laboratory studies indicate that etomidate is approximately 25 times more potent and has a therapeutic index six times greater than sodium thiopental. In contrast to most other induction agents, etomidate does not cause histamine release. Furthermore, tolerance does not occur with repeated administration. Etomidate's rapid distribution half life (t1/2α = 2.81 ± 1.64 min), short elimination half life 1/2β = 3.88 ± 1.11 hr) and rapid clearance (954 ± 178 ml/min) explain its rapid onset and short duration of action. The compound produces electroencephalographic changes and effects on cerebral blood flow, metabolism and intracranial pressure that are similar to sodium thiopental, suggesting that it may have a place in neurosurgery and as a “brain protective” agent in patients at risk of a brain hypoxic insult. Etomidate did not affect hepatorenal and hematologic function after repeated injections in animal toxicology studies, but few investigations addressing its effects on hepatic, renal, and neuromuscular function in man have been accomplished. The most noticeable side effects of etomidate include myoclonia, pain on injection and postoperative nausea and vomiting. Etomidate's most likely application will be as an anesthetic induction agent in patients with significant cardiovascular and/or respiratory disease or increased intracranial pressure, in patients with evidence of allergy to the barbiturates, and in combination with nitrous oxide in patients about to undergo short operations.