According to two new studies, although nitric oxide can halve the risk of developmental problems in premature babies with undeveloped lungs, the gas could be harmful to newborns who are too small and too ill.
Doctors Richard Martin and Michelle Walsh, both of Rainbow Babies and Children's Hospital in Cleveland, say the findings mean doctors should avoid using the treatment during the first week of life in premature babies who are seriously ill and weigh less than 1,000 grams (2.2 pounds).
The doctors say that short-term use of inhaled nitric oxide should not be considered an effective rescue therapy for very preterm infants with profound respiratory failure.
However for slightly larger, healthier premature infants the good news is, that the gas makes the lungs mature rapidly, cutting the risk of developmental problems in half, and that could help about half of the 60,000 premature infants born each year with dangerously underdeveloped lungs.
Pediatrician Michael Schreiber of the University of Chicago, whose team tracked 138 children, says that babies born at two pounds (0.97 kg) have only a 50 percent chance at 2 years of age of being considered totally normal.
The team found that by the second birthday, 24 percent of the children given nitric oxide had problems such as blindness, hearing loss and cerebral palsy, as against 46 percent for those 2-year-olds who did not receive the gas.
Schreiber says that not only does nitric oxide extend life in a large group of premature infants, it also improves the quality of life for the children and their parents.
But a second study qualified that conclusion.
The research team in the second study, which was led by Krisa Van Meurs of the Stanford University School of Medicine, found that out of 420 premature babies with severe respiratory failure, the 210 who were given nitric oxide were just as likely to die, or suffer lung damage, as the 210 who were given a placebo.
In this study, the research however, focused on babies who tended to be smaller and sicker than the ones in the Schreiber research.
The Van Meurs team also say they found that infants weighing over 1000 grams (35 ounces) benefited from nitric oxide, but those weighing less were more likely to die or develop severe brain bleeding than those who got standard care.
The Schreiber study was partly funded by INO Therapeutics, which makes the nitric oxide treatment.
The Van Meurs study was financed largely by the National Institute of Child Health and Human Development.
Both studies are published in the current edition of the New England Journal of Medicine.
The editorial by Richard Martin and Michelle Walsh also appears in the publication.