Human Surfactant Treatment of Respiratory Distress Syndrome Bicenter Trial

BACKGROUND:

Respiratory distress syndrome affects more than 40,000 infants annually in the United States. The overall mortality rate exceeds 20 percent and in infants weighing less than 1500 grams at birth, RDS is responsible for or contributes to the 30-70 percent mortality, depending on birthweight. The present customary treatment of RDS with intermittent mandatory ventilation is accompanied by sequelae such as extra-alveolar air leaks, intraventricular hemorrhage, and bronchopulmonary dysplasia in approximately 50 percent of survivors.

The respiratory distress syndrome of the newborn is a disorder in which the pulmonary surfactant is deficient. It has not been possible to completely replace natural components of surfactant with synthetic components and achieve a mixture which functions physiologically like pulmonary surfactant. Therefore, studies of replacement therapy for surfactant deficiency have used complete natural surfactants or derivatives of natural surfactant which contain the defined components of surfactant. The surfactant used in the clinical trial was derived from human amniotic fluid.

Two basic different strategies for surfactant treatment of respiratory distress syndrome have emerged: prophylactic, or preventilatory, treatment at or shortly after birth versus rescue treatment after the initiation of mechanical ventilation in instances of clinically confirmed respiratory distress syndrome. Although treatment at birth has the theoretic advantage of delivering surfactant more uniformly to the airways before mechanical ventilation, it has the disadvantages of delaying physiologic stabilization after birth and resulting in unnecessary treatment, at considerable cost, of 20 percent to 40 percent of infants born at or less than 30 weeks of gestation. Rescue therapy permits early physiologic stabilization and confirmation of respiratory distress syndrome, but with the theoretic disadvantages of early lung injury from mechanical ventilation in the surfactant-deficient lung and less uniform surfactant distribution. Previous comparative trials have been biased by incomplete study enrollment and inclusion of infants in preventilation treatment groups without evidence of surfactant deficiency or immaturity. In addition, outcomes have varied in placebo-treated infants.

DESIGN NARRATIVE: