Inhaled nitric oxide, a selective pulmonary vasodilator, is an effective treatment for persistent pulmonary hypertension in term neonates.1 Studies suggest that inhaled nitric oxide might also have a role in reducing the early lung injury associated with the development of bronchopulmonary dysplasia in preterm infants.2 Concerns regarding the safety of using inhaled nitric oxide in the preterm population have centered on the potential risk of intracranial hemorrhage because inhaled nitric oxide is known to affect platelet adhesion.1

Two randomized controlled trials of inhaled nitric oxide versus placebo gas were published recently in The New England Journal of Medicine. In a study by Kinsella et al,2 low-dose (5 ppm) inhaled nitric oxide was begun within 48 hours after birth and continued for a median of 14 days. The researchers found that early low-dose inhaled nitric oxide did not reduce the incidence of bronchopulmonary dysplasia in study infants weighing 500 to 1250 g at birth, but it did reduce bronchopulmonary dysplasia in infants weighing more than 1000 g at birth and the risk of brain injury in the overall population.2

In contrast, the trial by Ballard et al1 initiated inhaled nitric oxide later (7-21 days) and administered it longer (24 days), using a gradually decreasing dose beginning with 20 ppm. These investigators found improved survival without bronchopulmonary dysplasia in all weight groups without short-term adverse effects.1 An editorial accompanying these two studies in the same issue of the Journal points out that it is still too early to recommend the use of inhaled nitric oxide for preterm infants with respiratory failure outside of clinical trials. Inhaled nitric oxide is a costly treatment to administer without proven benefit and longer neurodevelopmental follow-up studies.3

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