Success of NO treatment for term babies doesn't extend to preemies

Contrary to earlier findings, inhaled nitric oxide (NO) therapy for lung immaturity in premature infants does not reduce an infant's risk of death or further lung problems, according to a study by the National Institute of Child Health and Human Development (NICHD) of the National Institutes of Health that appeared in the July 7 issue of the New England Journal of Medicine.

"Premature infants weighing less than 1,500 g should not receive inhaled NO therapy unless they are part of a research study, said NICHD Director Duane Alexander, MD.

Inhaled NO is effective in full-term infants with lung complications—those whose lungs are fully formed and in whom complications typically are a result of lung infection. Because treatment works well for term infants, researchers had been interested in whether it can be used to treat lung complications in preterm infants. (Earlier research in preterm infants treated with inhaled nitric oxide therapy showed varied results.)

Researchers with NICHD's Neonatal Research Network enrolled 420 infants born at less than 34 weeks' gestation and who weighed between 401 and 1,500 g (14 ounces to 3 pounds, 2 ounces) at birth. All infants required assisted ventilation and had a diagnosis of respiratory distress syndrome, sepsis or pneumonia, or other severe breathing problems. The infants were randomly assigned to receive either inhaled nitric oxide or a placebo.

There was no difference in outcome between infants who received the inhaled nitric oxide and those who did not. Sixty percent of the infants who received it and 68% of those who did not developed bronchopulmonary dysplasia. Both groups had a high death rate (52% of the inhaled nitric oxide group, and 44% in the placebo group).

Earlier research on inhaled nitric oxide on premature infants who had a breathing problem showed that therapy had potential benefit. The infants in that study were larger and less critically ill than those in this study, however.

Report author Rosemary Higgins, MD, codirector of the Neonatal Perinatal Medicine Fellowship Program and associate professor in the department of pediatrics, division of neonatology, Georgetown University and Children's Medical Center, said that smaller infants presumably were unable to benefit from inhaled nitric oxide therapy because their lungs were insufficiently developed.

More from Contemporary Pediatrics Dateline.