Exogenous surfactants in a piglet model of acute respiratory distress syndrome

Evidence for surfactant dysfunction in acute respiratory distress syndrome (ARDS) suggests a role for exogenous surfactant which contains apoprotein for resistance to protein inhibition. We compared the effects of KL-4-Surfactant, an artificial preparation containing a synthetic 21 amino acid peptide with SP-B-like activity, with Exosurf(R), an artificial protein-free surfactant, and Survanta(R), a bovine protein-containing surfactant, in a saline lung lavage model of ARDS in neonatal piglets. Two sequential series of lung lavages were performed to lower Pa-O2 < 100 mm Hg, each followed by administration of surfactant or air and a 90-min observation period. Progressive lung injury was demonstrated by deterioration in pulmonary function, increasing bronchoalveolar lavage protein, and changes in histopathology. All surfactants improved oxygenation, although oxygenation was generally better with Survanta and KL-4-Surfactant. Further, Survanta and KL-4-Surfactant groups showed improvement in ventilation, with decreases in Pa-CO2 and increases in FRC. Only KL-4-Surfactant demonstrated greater pressure-volume characteristics and lower bronchoalveolar protein than those of Controls. We conclude that the physiologic effects of KL-4-Surfactant are more like Survanta in this model. We speculate that KL-4-Surfactant may improve pulmonary function, reduce alveolar protein leak, and thus be efficacious in the treatment of ARDS.