Inhaled nitric oxide (iNO) is commonly used to treat which neonatal condition?

• A. Meconium aspiration syndrome
• B. Persistent pulmonary hypertension of the newborn
• C. Transient tachypnea of the newborn
• D. Neonatal sepsis

Answer: (B)

Inhaled nitric oxide acts as a selective pulmonary vasodilator, relaxing smooth muscle in the lungs to lower pulmonary vascular resistance and improve oxygenation without causing widespread hypotension. This is most beneficial in persistent pulmonary hypertension of the newborn, where high pulmonary vascular resistance shunts blood away from the lungs and into the systemic circulation. By dilating the pulmonary vessels, iNO increases perfused lung areas, reduces right-to-left shunting at the foramen ovale and ductus arteriosus, and improves arterial oxygenation. While meconium aspiration syndrome can involve PPHN, iNO is used to treat the pulmonary hypertension component, not MAS itself; transient tachypnea of the newborn and neonatal sepsis are managed with supportive care and/or antibiotics, not primarily with iNO.