EM SAQs · Vasoactive drugs in resuscitation
Match the pressor to the shock — receptors and doses
ACEM-style SAQ on vasoactive receptor matching, septic shock dosing and SOAP II.
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Receptors. Noradrenaline: α1 > β1 → SVR↑ with modest inotropy. Adrenaline: α1+β1+β2 (β-predominant at low dose). Vasopressin: V1 catecholamine-independent vasoconstriction. Dopamine: dose-dependent D1 → β → α.
Septic shock first-line. Noradrenaline 0.05–1.0 mcg/kg/min titrated to MAP ≈65 mmHg after adequate fluid, with source control and antibiotics.
[3]Vasopressin adjunct. Fixed 0.01–0.04 units/min (commonly 0.03) to spare catecholamines; do not titrate above 0.04 (ischaemia risk).[2][3]
Why not dopamine first-line. SOAP II: more arrhythmias with dopamine, no mortality benefit; "renal-dose" dopamine does not protect the kidney.[1]
Phenotype note. If septic cardiomyopathy (low CO on echo), add dobutamine; pure hypovolaemia needs volume/blood first, not pressors alone.[3]
References3ShowHide
- [1]De Backer D, et al. Comparison of dopamine and norepinephrine in the treatment of shock. NEJM, 2010.PMID 20200382
- [2]Russell JA, et al. Vasopressin versus norepinephrine infusion in patients with septic shock. NEJM, 2008.PMID 18305265
- [3]Evans L, Rhodes A, Alhazzani W, et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Intensive Care Medicine, 2021.PMID 34599691