EMS Pharmacology Deep Dive: Vasopressors in the Field

Vasopressors are among the most tested — and most misunderstood — drug class on the paramedic exam. Understanding receptor effects makes the choice obvious.

Receptors 101

• Alpha-1: vasoconstriction (↑ SVR, ↑ BP)
• Beta-1: ↑ inotropy and chronotropy (heart)
• Beta-2: bronchodilation and vasodilation
• Dopaminergic: renal/mesenteric dilation (low doses)

Epinephrine

Alpha and beta agonist. Cardiac arrest (1 mg IV/IO q3–5), anaphylaxis (0.3 mg IM), symptomatic bradycardia infusion (2–10 mcg/min). Push-dose (10 mcg/mL, 0.5–2 mL) buys time in peri-arrest hypotension.

Norepinephrine

Predominantly alpha with modest beta-1. First-line for septic shock and post-ROSC hypotension. Central line preferred; peripheral acceptable short-term with a large vein.

Dopamine

Dose-dependent: low = dopaminergic, mid = beta-1, high = alpha. Falling out of favor for shock but still on many protocols for symptomatic bradycardia (5–20 mcg/kg/min).

How to pick on the exam

Anaphylaxis → epi IM. Cardiac arrest → epi IV/IO. Post-ROSC or septic shock → norepi. Symptomatic bradycardia unresponsive to atropine → epi or dopamine infusion. Memorize those four and most vasopressor questions collapse.