In intraoperative anaphylaxis, which vasopressor choice is appropriate?

• A. Only epinephrine IV bolus.
• B. Only dopamine infusion.
• C. Phenylephrine or norepinephrine.
• D. Vasopressin alone.

Answer: (C)

When intraoperative anaphylaxis causes severe hypotension, the primary goal is to rapidly restore vascular tone and perfusion by choosing a vasopressor with strong alpha-adrenergic effect. Phenylephrine provides quick, titratable alpha-1–mediated vasoconstriction, raising systemic vascular resistance and blood pressure without substantially increasing heart rate, which helps avoid tachyarrhythmias or increased myocardial oxygen demand during surgery. Norepinephrine combines potent alpha-1 vasoconstriction with some beta-1 activity, improving blood pressure and organ perfusion while often causing less tachycardia than epinephrine. These properties make them appropriate choices to counteract the vasodilatory shock of anaphylaxis in the operating room.

Dopamine has variable dose-related effects and can provoke arrhythmias and unpredictable responses. Vasopressin alone does not quickly correct the vasodilation and usually serves as an adjunct to catecholamines rather than the sole agent. Epinephrine remains the drug of choice for systemic anaphylaxis overall, especially for bronchospasm, but for the specific goal of rapidly supporting blood pressure in this intraoperative context, phenylephrine or norepinephrine are the most appropriate choices.