Pharmacologic agents that might reduce pulmonary vascular resistance in primary pulmonary hypertension include all of the following except which?

Pharmacologic agents that might reduce pulmonary vascular resistance in primary pulmonary hypertension include all of the following except which?

• A. Prostaglandin I2 (epoprostenol)
• B. Oxygen
• C. Nitric oxide
• D. Nitrous oxide

Answer: (D)

The key idea is that reducing pulmonary vascular resistance in idiopathic pulmonary hypertension relies on agents that directly dilate the pulmonary arteries or counteract hypoxic vasoconstriction. Prostaglandin I2 analogs like epoprostenol cause potent pulmonary vasodilation and also inhibit platelet aggregation, which lowers PVR. Oxygen helps because hypoxemia drives pulmonary vasoconstriction; by increasing the alveolar oxygen tension, it reduces that constriction and lowers PVR. Inhaled nitric oxide is a selective pulmonary vasodilator that relaxes smooth muscle in the pulmonary arteries, lowering PVR while largely avoiding systemic hypotension. Nitrous oxide, however, does not have a meaningful effect on pulmonary vascular resistance and is not used to treat PAH for this purpose.

The key idea is that reducing pulmonary vascular resistance in idiopathic pulmonary hypertension relies on agents that directly dilate the pulmonary arteries or counteract hypoxic vasoconstriction. Prostaglandin I2 analogs like epoprostenol cause potent pulmonary vasodilation and also inhibit platelet aggregation, which lowers PVR. Oxygen helps because hypoxemia drives pulmonary vasoconstriction; by increasing the alveolar oxygen tension, it reduces that constriction and lowers PVR. Inhaled nitric oxide is a selective pulmonary vasodilator that relaxes smooth muscle in the pulmonary arteries, lowering PVR while largely avoiding systemic hypotension. Nitrous oxide, however, does not have a meaningful effect on pulmonary vascular resistance and is not used to treat PAH for this purpose.