Etomidate

Keyword

Etomidate

Characteristics

• an imidazole derivative (R-(+)-pentylethyl-1H-imidazole-5 carboxylate sulfate)
• provides stable hemodynamics and minimal respiratory depression
• most appropriate in patients with cardiovascular disease, reactive airway disease, intracrania hypertension, or any combination of disorders indicating the need for an induction agent with limited or beneficial physiologic side effects.
• (giant aneurysm clipping과 같은 수술, intravascular volume status를 알 수 없는 trauma 환자의 수술, MI나 Angina 환자의 minor op시 사용할 수 있음.)

Pharmacodynamics

1. Effects on the CNS
• Extrapyramidal motor activity를 조절하는 신경계를 disinhibition시켜서, 30-60%의 확률로 myoclonus를 유발할 수 있음.
• Cerebral metabolic rate, Cerebral blood flow, ICP를 감소시킴.
• barbiturate나 propofol보다 PONV를 더 일으킴.
1. Effects on the respiratory system
• barbiturate나 BZD보다 ventilation에 영향을 덜 줌. opioid 병용하지 않는다면, etomidate intubation dose의 단독사용으로는 apnea를 일으키지 않음.
1. Effects on the cardiovascular system
• 영향이 미미함. 심근수축력과 cardiac output이 변하지 않음.
• 말초혈관저항을 감소시켜서 ABP가 약간 감소할 수 있음.
• Histamine 분비를 일으키지 않음.
1. Endocrine effects
• Cortisol, aldosterone 합성에 관여되는 효소의 작용을 억제.(adrenocortical suppression)

Doses

• induction of general anesthesia : 0.2-0.6 mg/kg IV

(opiate, BZD, barbiturate의 premedication시 induction dose는 더 줄어들 수 있음.)

• Routine induction dose : 0.3 mg/kg
• Onset time : rapid (one arm–brain circulation)
• adrenocortico suppressive effect로 인하여 corticosteroid 합성을 방해할 수 있으므로, sedation은 매우 짧은 용도 외에는 잘 쓰이지 않음. 같은 이유로 continuous infusion은 금기.

Other uses

• Treatment in Hypercortisolemia

Side effects

• nausea, vomiting (associated with PONV)
• pain on injection ( Pain on injection may be reduced by injecting IV lidocaine, 20 to 40 mg immediately before injection of etomidate.)
• myoclonic movement (reduced by premedication with a hypnotic agent such as midazolam or a small dose of magnesium 60 to 90 seconds before the induction dose of etomidate is given.)
• hiccups

Reference

Miller’s Anesthesia, 8th edition, Ch. 30, P. 850

Morgan and Mikhail's Clinical Anesthesiology, 5th edition, Ch.9, P.184