Effects of Tracheal Instillation of Natural Surfactant in Premature Lambs. I. Clinical and Autopsy Findings

Abstract

Summary: Ten pairs of twin lambs 118–122 days of gestation were given cither natural surfactant or diluent endotracheally before the first breath. By using the premature twin lamb model, we have been able to show that instillation of natural surfactant produced 100% survival for the duration of the study period (2 hr); stable blood gases on room air; lungs that became increasingly compliant while on the respirator; generally well aerated lungs at autopsy; good lung pressure-volume relationships; normal lung surface tension measurements; and histologic evidence of good alveolar expansion with large amounts of free intraluminal phospholipid, no epithelial damage, and no hyaline membranes. It is concluded that tracheal instillation of natural surfactant into the premature lamb protects the lungs from developing many features characteristic of the respiratory distress syndrome. Speculation: The success of these experiments is possibly due to the use of “whole” natural surfactant rather than some of its component chemicals. The precise biochemistry and physical chemistry of surfactant is very controversial, and for therapeutic purposes, it might be best for the moment to concentrate on the natural biologic product.