Which statement about inhaled nitric oxide in PPHN is true?

• A. It has no effect on oxygenation
• B. It increases ECMO usage
• C. It improves oxygenation and reduces ECMO use
• D. It worsens pulmonary hypertension

Answer: (C)

Inhaled nitric oxide acts as a selective pulmonary vasodilator, meaning it specifically relaxes the vessels in the lungs without causing widespread systemic dilation. In PPHN the pulmonary vascular resistance stays high, leading to reduced blood flow through aerated lung areas and right-to-left shunting through fetal pathways, which worsens oxygenation. By dilating the pulmonary vessels, inhaled NO improves distribution of blood flow to well-ventilated lung regions, raises PaO2, and often decreases the need for ECMO as a rescue or bridge therapy. The statement that it has no effect on oxygenation isn’t correct because its pulmonary-specific action tends to improve oxygenation in many infants with PPHN. It doesn’t worsen pulmonary hypertension; it helps reduce it locally. It also doesn’t typically increase ECMO usage; in fact, it can lower that need when effective. Remember that some infants may not respond, and careful monitoring is needed for potential methemoglobinemia and smooth weaning to avoid rebound hypertension.