LUNG EXPANSION IN THE PREMATURE RABBIT FETUS AFTER TRACHEAL DEPOSITION OF SURFACTANT

TLDR

The study tests whether tracheal surfactant deposition before the first breath can enhance lung expansion and serve as a prophylaxis for idiopathic respiratory distress syndrome. Surfactant was isolated from adult rabbit alveolar wash, concentrated by centrifugation, and tracheally instilled into 28‑day gestation fetuses, whose lungs were then fixed at 10 cm H₂O for analysis. Surfactant‑treated fetuses displayed mature pressure‑volume curves with wide hysteresis and pronounced parenchymal air expansion, whereas controls showed premature curves with minimal hysteresis and limited expansion.

Abstract

Concentrated "surfactant" was obtained by centrifugation of alveolar wash from adult rabbits for 1 hour at 4°C, 1,000xG, and deposited in the trachea of premature rabbit fetuses, killed at the gestational age of 28 days, i.e., 1 day before appreciable amounts of surface active phospholipids are naturally present in the pulmonary fluid. Pressure-volume tracings revealed a mature pattern in the surfactant-treated animals, with wide hysteresis. Significantly less air entered the lungs of control fetuses from the same litters, and the pressure-volume tracings from these animals showed a premature pattern, with minimal hysteresis. The lungs of the fetuses were fixed in formalin under the endotracheal deflation pressure of 10 cm H20. Histological examination of the lungs revealed moderate or prominent air expansion of the parenchyma in surfactant-treated animals, whereas no or only slight air expansion characterized the controls. Tracheal deposition of surfactant prior to the first breath thus seems to enhance the air expansion of the premature lung, and might possibly be applied as a method for prophylaxis against the idiopathic respiratory distress syndrome, which is related to deficiency of surface active phospholipids in the pulmonary fluid.