Isolation of Human Surfactant from Amniotic Fluid and a Pilot Study of Its Efficacy in Respiratory Distress Syndrome

Abstract

Isolation of a sterile, surface-active human surfactant complex from amniotic fluid is described. Its effects on respiratory failure of five very low-birth-weight infants (974 ± 61 g) with severe RDS were studied before and after surfactant administration and were compared with those of a similar group of untreated infants with severe respiratory distress syndrome (RDS). Human surfactant (60 mg/kg) in 3.5 mL of saline was given as a single bolus intratracheally 6 ± 1 hours after birth with the following effects: Pao₂ increased from 69 ± 11 mm Hg to 239 ± 19 mm Hg within five minutes, and within 1 hour fraction of inspired oxygen (FiO₂) decreased from 0.94 ± 0.03 to 0.49 ± 0.03, mechanical ventilator pressure requirements decreased significantly, PaCo₂ dropped, and the pH increased. Air bronchograms on chest roentgenograms lessened within five hours. In four infants the beneficial effects lasted eight to 15 hours, and although thereafter their respiratory conditions deteriorated somewhat, the RDS was less severe than before surfactant administration, and there were no associated pulmonary complications. However, a fifth infant had severe respiratory failure after striking improvement that lasted fewer than three hours, and subsequent interstitial emphysema, bronchopulmonary dysplasia, and intraventricular hemorrhage occurred. There were no detectable side effects with surfactant administration, although a search for immunologic complications continues. Protease activity in lung effluent from the treated infants was lower during the first week of life than among the comparison group, suggesting a lessening of lung injury by surfactant treatment. RDS among patients treated with one dose of human surfactant tended to be milder overall than RDS among control subjects.