SELECTED LOBAR INJURY AFTER INFUSION OF OLEIC-ACID

A model of respiratory distress was developed using sheep in which an isolated lobar injury was induced by infusion of oleic acid into a selected lobar artery. The directed insult permitted acute and chronic phase study without needing intensive pulmonary support. One hour after selective lobar injury the affected pulmonary venous oxygenation (PpVO2) was reduced from > 310 to 66-90 Torr. PpVO2 was most impaired at 48 h (40-55 Torr), but showed improvement by 96 h postinjury. Radionuclide estimates of lobar ventilation and perfusion demonstrated an initial fall in ventilation by 51% and a corresponding 41% reduction in perfusion. By 24 h the depression of perfusion matched that of ventilation. Sequential light and scanning electron microscopy demonstrated the presence of a nonhomogeneous injury with areas of complete parenchymal replacement by fibrous tissue and those with minimal architectural distortion. The selective injury model offers a useful method for the evaluation of the effects of various agents on the acute and chronic response of the lung to injury.