Premature Babies Not Aided by NO

In term infants, whose lungs are fully formed, these complications result from lung infection. For the treatment, nitric oxide gas is mixed with oxygen and given to an infant through a breathing apparatus. The treatment relaxes the blood vessels in the lungs, allowing the lungs to absorb oxygen more easily. Because this treatment helps infants, researchers had been interested in its possible use to treat lung complications in preterm babies.

A team of researchers with the U.S. National Institute of Child Health and Human Development (NICHD, Bethesda, MD, USA; www.nichd.nih.gov) enrolled 420 infants born at less than 34 weeks' gestation, weighing between 14 ounces to three pounds, two ounces. All infants required assisted ventilation and had a diagnosis of respiratory distress syndrome, sepsis or pneumonia, or other breathing problems. The infants were randomly assigned to receive either inhaled nitric oxide or a placebo.

The results showed no difference between the infants who received the inhaled nitric oxide and those who did not: 60% of infants who received it and 68% of those who did not developed bronchopulmonary dysplasia, a serious lung condition involving lung inflammation and scarring. Both groups had high death rates (52% in the inhaled nitric oxide group and 44% in the placebo group.)

"Contrary to our hopes as neonatologists, inhaled nitric oxide treatment did not reduce the incidence of death or further lung problems,” said co-author Dr. Rosemary Higgins, of NICHD's pregnancy and perinatology branch. "The smallest and sickest of infants were not sufficiently developed.”

The researchers found that infant weight affected the outcome among infants receiving inhaled nitric oxide. Infants in this group weighing between 1,000 and 1,500 g had a significantly lower death rate than infants in the placebo group. Infants weighing less than 1,000 grams in this group had a higher death rate than those in the placebo group. In addition, infants receiving inhaled nitric oxide through conventional mechanical ventilation had a higher mortality rate than those receiving the therapy through high-frequency ventilation.

"We have more work to do to better understand how to best help premature infants with severe lung problems,” observed Dr. Higgins.




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