A MODEL FOR ACUTE RESPIRATORY-FAILURE INDUCED BY TRACHEAL INSTILLATION OF HOMOLOGOUS PLASMA OR PROTEIN-RICH PULMONARY-EDEMA FLUID

Both ARDS and established neonatal RDS are characterized by intraalveo lar protein-rich oedema fluid, capable of inhibiting surfactant functi on. This study investigated the possibility to use homologous plasma o r pulmonary oedema fluid to induce acute respiratory failure due to in hibition of pulmonary surfactant. The study demonstrated that both pla sma and oedema fluid, intratracheally instilled in healthy rats, led t o respiratory failure as evidenced by increase of PaCO2 and decrease o f PaO2, and to increased minimal surface tension of bronchoalveolar la vage material due to interference with the surfactant layer. In contra st to rats receiving plasma, bronchoalveolar lavage fluid of rats rece iving oedema fluid showed a high percentage of neutrophils, suggesting the presence of chemotactic factors in the oedema fluid. It is conclu ded that both plasma and oedema fluid have comparable inhibitory capac ity on surfactant function. This model, which leads to an ARDS-like fo rm of acute respiratory failure, may be useful for the evaluation of v arious aspects of inhibition of exogenous surfactant by high alveolar protein concentrations.