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Cardiovascular Stability Induction — FRCA Primary MCQ

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EasyPharmacology - Intravenous AnaestheticsCardiovascular Stability InductionFRCA Primary

Which intravenous induction agent generally causes the least change from baseline in heart rate, systemic vascular resistance and myocardial contractility during induction of general anaesthesia?

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Correct answer: EEtomidate

Etomidate is correct. At an appropriate induction dose it usually produces the least change in heart rate, systemic vascular resistance and myocardial contractility, so arterial pressure is relatively well preserved. Propofol commonly causes hypotension through vasodilatation and some myocardial depression; thiopentone and induction-dose midazolam can also reduce vascular tone and cardiac output. Ketamine often preserves arterial pressure but does so through sympathoadrenal stimulation, commonly increasing heart rate, blood pressure and myocardial oxygen demand; its direct myocardial-depressant effect may become apparent in catecholamine-depleted patients. Etomidate is not physiologically inert: it has no analgesic action, may cause myoclonus, and reversibly inhibits adrenal 11β-hydroxylase, causing transient suppression of cortisol and aldosterone after a single dose.

Reference: Valk BI, Struys MMRF. Etomidate and its Analogs: A Review of Pharmacokinetics and Pharmacodynamics. Clinical Pharmacokinetics. 2021;60:1253–1269. https://pubmed.ncbi.nlm.nih.gov/30686305/