Preterm Babies : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Leslie Carter was carrying quadruplets, and she knew she would probably deliver early, as is often the case with multiple births.

Surfactants were not approved for general use at the time, but the Indiana hospital had one through an FDA treatment program that allows lifesaving drugs to be used in certain hospitals before they receive approval.

"We were aware of the drug called surfactant," Leslie Carter remembers, "and we were really glad to be in a hospital where they could use that."

Katelin, Katherine, Abigail, and Elizabeth Carter were born nearly 10 weeks early on Jan. 30, 1990, weighing less than 3 pounds each. They all developed respiratory distress syndrome, were treated with a surfactant, and placed on ventilators. At first their progress was slow, but after about two months in the hospital, all were home and doing well.

"We've been very fortunate," their mother says. "They're really healthy."

The Indiana University Medical Center has participated in clinical trials of both approved pulmonary surfactants for about four years, according to associate professor of pediatrics William A. Engle, M.D., who treated the Carter quadruplets and Benjamin McClatchey.

He says his colleagues have used both kinds, with promising results.

"I think the major benefit of surfactant is that it reduces the risks associated with respiratory distress syndrome," Engle says, "and we know that about 50 percent of the babies less than 1,500 grams [3.3 pounds] will have severe hyaline membrane disease."

Bellows for Baby

A surfactant is no miracle cure for respiratory distress syndrome, however. Like Benjamin McClatchey and the Carter quadruplets, infants born too early may still spend months hooked to ventilators to help them breathe.

The newest kind of respirator for newborns is called a "high-frequency ventilator," which works very differently from the older, conventional ventilators.

Conventional ventilators have been used on infants for years and are largely responsible for the drastic drop in infant deaths from RDS throughout the 1970s. The high-frequency concept, a modification of conventional ventilation, was first described in 1959 but wasn't tested on infants until the early 1980s or approved by FDA until 1987.

Conventional ventilators force air down an infant's lungs with pressures high enough to expand them, sometimes damaging the delicate airways in the process.

A high-frequency ventilator, however, supplies oxygen to the baby through tiny, rapid puffs of air that barely move the lungs. It creates a vibrating column of air in the lungs without forcing them to expand in the traditional manner.

While a conventional ventilator "breathes" only about 14 times per minute, a high-frequency ventilator puffs at least 150 times per minute.

It's still not scientifically proven, however, whether high-frequency ventilators are better in the long run than the older machines for all premature infants. Doctors use them mostly when conventional ventilation isn't successful.

Since 1987, FDA has approved for use on infants three high-frequency ventilators made by Bunnell Inc. of Salt Lake City, Utah, Infrasonics Inc. of San Diego, Calif., and SensorMedics Corp. of Yorba Linda, Calif.

Despite the benefits of both surfactants and high-frequency ventilators, problems remain.

Neither the surfactant drugs nor the high-frequency ventilators seem to reduce the incidence of a chronic lung condition stemming from long-term ventilator use called bronchopulmonary dysplasia, or BPD.

"That's kind of disappointing," says Dorothy Gail, Ph.D., chief of the Cell and Developmental Biology Branch at the National Heart, Lung, and Blood Institute. "Surfactant's great for RDS, but as far as the more chronic lung diseases go, it's not what everyone had hoped."

Benjamin McClatchey, for example, developed BPD. He still requires oxygen fed to his nose from a portable tank at home.

About the Author

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