Clinical pathophysiology of persistent pulmonary hypertension of the newborn and the role of inhaled nitric oxide therapy.

Inhaled NO can cause marked improvement in oxygenation when optimal lung inflation is achieved and systemic blood volume and vascular resistance are adequate. However, inhaled NO alone is unlikely to cause sustained improvements in oxygenation in neonatal hypoxemic respiratory failure associated with severe parenchymal lung disease without extrapulmonary shunting. Inhaled NO may be an important tool in the management of severe PPHN when its application is limited to patients with severe extrapulmonary shunting.