NO is administered by inhalation (see Preparations Available) to newborns with hypoxic respiratory failure associated with pulmonary hypertension. The current treatment for severely defective gas exchange in the newborn is with extracorporeal membrane oxy-genation (ECMO), which does not directly affect pulmonary vascular pressures. NO inhalation dilates pulmonary vessels, resulting in decreased pulmonary vascular resistance and reduced pulmonary artery pressure. Inhaled NO also improves oxygen-ation by reducing mismatch of ventilation and perfusion in the lung. Inhalation of NO results in dilation of pulmonary vessels in areas of the lung with better ventilation, thereby redistributing pulmonary blood flow away from poorly ventilated areas.NO inhalation does not typically exert pronounced effects on the sys-temic circulation. Inhaled NO has also been shown to improve cardiopulmonary function in adult patients with pulmonary artery hypertension.An additional approach for treating pulmonary hypertension is to potentiate the actions of NO in pulmonary vascular beds. Due to the enrichment of PDE-5 in pulmonary vascular beds, PDE-5 inhibitors such as sildenafil and tadalafil induce vasodilation and marked reduc-tions in pulmonary hypertension.