The role of nitric oxide in the treatment of neonatal pulmonary hypertension

Nitric oxide production appears to be decreased in infants with persistent pulmonary hypertension (PPHN). Inhaled nitric oxide may improve oxygenation by two mechanisms: increased pulmonary blood flow and improved ventilation-perfusion matching. Nitric oxide inhalation has been tested in newborns with PPHN, congenital heart diseases, and bronchopulmonary dysplasia. We present a review of the articles concerning inhaled nitric oxide for infants with PPHN. Overall, 59% of the neonates had an initial improvement in oxygenation in response to nitric oxide inhalation. A sustained response was observed in 60% of the infants. Patients with extrapulmonary shunting, clear chest radiographs, and adequate lung volume seem to have a better response, whereas patients with congenital diaphragmatic hernia, severe sepsis, and alveolar capillary dysplasia are more likely to fail. To define the benefit-risk ratio, six prospective randomized trials are currently in progress.