Which inhaled therapy may be used to improve oxygenation in select ARDS patients by reducing pulmonary vascular resistance?

• A. Nebulized antibiotics
• B. Inhaled bronchodilators
• C. Inhaled corticosteroids
• D. Inhaled nitric oxide (iNO) or epoprostenol

Answer: (D)

In ARDS, improving oxygenation can come from increasing blood flow to well‑ventilated lung regions, which reduces pulmonary vascular resistance and improves ventilation–perfusion matching. Inhaled nitric oxide works by delivering a selective pulmonary vasodilator directly to the lungs, dilating vessels where ventilation is good and thereby lowering PVR with minimal systemic effects, often boosting arterial oxygenation in select patients. Epoprostenol (inhaled prostacyclin) acts similarly as another inhaled vasodilator. These therapies are used selectively because the oxygenation improvement varies and they don’t improve mortality; potential risks include hypotension and, for iNO, methemoglobinemia and NO2 exposure. Other inhaled therapies like nebulized antibiotics, bronchodilators, or inhaled corticosteroids don’t reduce pulmonary vascular resistance to enhance oxygenation in ARDS, so they’re not the mechanism at play here.