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Nitric Oxide Treatment May Help Premature Babies
Very small premature babies, those under three pounds, are at high risk for
delayed growth and lasting developmental problems. Two new studies show that
treating premature babies with nitric oxide gas can help prevent chronic lung
disease, and may also protect against brain injury.
In 2004, more than a half million babies in the U.S. (about 12.5%) were born prematurely,
before completing 37 weeks of pregnancy. Because their lungs are not fully developed,
premature infants have trouble breathing on their own. Oxygen and, in many cases,
a mechanical breathing machine, or ventilator, can help premature infants breathe
until the lungs have a chance to mature. However, this treatment can damage the
lungs and interfere with normal development, leading to a chronic lung disease
known as bronchopulmonary dysplasia (BPD). BPD brings a higher risk of ongoing
lung problems such as pulmonary hypertension (high blood pressure in the arteries
that supply blood to the lungs); neurodevelopmental problems such as cerebral palsy;
learning disabilities; hearing and vision problems; heart problems and impaired
growth. Very small babies are at high risk for BPD even if they only require ventilator
care for short periods
Previous studies have shown that inhaled nitric oxide (iNO) can help full-term
newborns with severe respiratory failure. Two research teams set out to study
iNO treatment in premature and very low birthweight babies. The studies, which
were supported by NIH's National Heart, Lung, and Blood Institute, involved infants
born at less than 34 weeks of pregnancy who weighed between about one and three
pounds at birth and needed a ventilator to help them breathe. INO Therapeutics
of Clinton, NJ, supplied nitric oxide and gas delivery equipment for the two
studies. The results were published in the July 27, 2006, issue of the New
England Journal of Medicine.
In the first study, a team led by Dr. John P. Kinsella of the Pediatric Heart
Lung Center at Children's Hospital in Denver gave nearly 800 babies either iNO
or a harmless placebo gas for comparison starting within the first 48 hours of
life and continuing through 21 days or until they no longer needed breathing
assistance. Treatment did not lower the overall incidence of BPD at 36 weeks,
but it did appear to cut the risk of BPD in half among the larger babies who
weighed around two and a half pounds at birth. In addition, significantly fewer
babies treated with iNO had evidence of brain damage in ultrasound scans prior
to hospital discharge.
In the second study, a team led by Dr. Roberta A. Ballard, professor of pediatrics
and obstetrics and gynecology at The Children's Hospital of Philadelphia and
the University of Pennsylvania, randomly selected nearly 600 very low birthweight
premature babies at high risk of developing BPD to begin iNO treatment or a placebo
at between seven and 21 days of age. Treatment continued for at least 24 days.
More babies treated with iNO survived without BPD by 36 weeks than those who
didn't receive treatment (44% versus 37%). The benefits were even more apparent
among the infants who began treatment between seven and 14 days after birth — those
babies had twice the rate of survival without BPD as those who did not receive
treatment. In addition, iNO was associated with less severe lung disease among
the treated infants who did develop BPD.
Previous studies using iNO have had mixed results, but the results of these
current studies are promising. The researchers are cautiously optimistic that
this therapy may prove to be beneficial. However, the children in these studies
need to be followed for longer periods to better understand the long-term effects
of iNO treatment on their development. Both teams will continue to follow their
participants — the first team for another four and a half years, the second
for another two.
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