Surfactant abnormalities and adult respiratory failure.

Surfactant abnormalities have been implicated in the development of the acute respiratory distress syndrome in adults. Experimental studies show that surfactant inhibition by protein-leak into the alveolar space is of major importance under these circumstances. Fibrin(ogen)-surfactant-interaction appears to contribute to disturbances of surfactant function with subsequent alveolar instability and ventilation-perfusion-mismatch. In a prospective study in severely injured patients, the surfactant in serially obtained bronchoalveolar lavage fluids was investigated. An early leakage of plasma proteins into the alveolar space was noted in those patients, who developed severe ARDS. Moreover, deterioration of surfactant function was markedly more pronounced in those patients than in trauma victims who developed only mild pulmonary dysfunction. In addition to the protein-leakage, a progressive decrease of the surfactant-specific dipalmitoyl-phosphatidylcholine was noted, significantly correlated with the deterioration of surfactant function and the severity of respiratory failure. In conclusion, experimental and clinical studies show surfactant abnormalities in the adult respiratory distress syndrome. Plasma protein-leakage and progressive alteration of alveolar type II surfactant secretion appear to be of major importance.