Early use of inhaled nitric oxide is most likely beneficial in which scenario?

• A. Infants with severe infection without pulmonary hypertension
• B. Extremely preterm infants on high frequency ventilation
• C. Infants with RDS that is complicated by pulmonary hypertension
• D. Term infants with TTN

Answer: (C)

Inhaled nitric oxide acts as a selective pulmonary vasodilator, lowering pulmonary vascular resistance and improving oxygenation by reducing right-to-left shunting through fetal circulatory pathways. This makes it most helpful when pulmonary hypertension accompanies lung disease.

The scenario where RDS is complicated by pulmonary hypertension fits this best. The pulmonary vasoconstriction associated with pulmonary hypertension worsens hypoxemia, and inhaled nitric oxide can selectively dilate the pulmonary vessels, improve perfusion to ventilated lung segments, and enhance oxygenation without causing systemic vasodilation. This targeted effect can reduce the need for more invasive therapies and improve gas exchange.

Infection without pulmonary hypertension doesn’t create the vasoconstricted pulmonary bed that iNO can correct, so benefit is unlikely. Extremely preterm infants on high-frequency ventilation have not consistently shown clear net benefits from routine iNO use and may face risks, so it’s not the most appropriate scenario. Term infants with TTN typically do not have pulmonary hypertension, so iNO isn’t indicated there either.

Therefore, the early use of inhaled nitric oxide is most beneficial when the infant has respiratory distress syndrome complicated by pulmonary hypertension.