Which vascular effect may occur with phenylephrine?

Which vascular effect may occur with phenylephrine?

• A. May decrease systemic vascular resistance
• B. May decrease renal perfusion
• C. May increase pulmonary vascular resistance
• D. May increase systemic vascular resistance

Answer: (C)

Phenylephrine is a selective alpha-1 adrenergic agonist, so its primary vascular effect is vasoconstriction of systemic arteries and veins, which raises systemic vascular resistance and blood pressure. In addition to this systemic effect, alpha-1 stimulation can also cause constriction in the pulmonary vasculature, leading to an increase in pulmonary vascular resistance. This pulmonary effect is clinically important because an elevated PVR increases right ventricular afterload and can worsen right heart function, especially in patients with pulmonary hypertension or RV dysfunction. Thus, while the main action is to raise systemic vascular resistance, an increase in pulmonary vascular resistance is a plausible and clinically relevant vascular effect of phenylephrine.

Phenylephrine is a selective alpha-1 adrenergic agonist, so its primary vascular effect is vasoconstriction of systemic arteries and veins, which raises systemic vascular resistance and blood pressure. In addition to this systemic effect, alpha-1 stimulation can also cause constriction in the pulmonary vasculature, leading to an increase in pulmonary vascular resistance. This pulmonary effect is clinically important because an elevated PVR increases right ventricular afterload and can worsen right heart function, especially in patients with pulmonary hypertension or RV dysfunction. Thus, while the main action is to raise systemic vascular resistance, an increase in pulmonary vascular resistance is a plausible and clinically relevant vascular effect of phenylephrine.