Selected lobar injury after infusion of oleic acid

Abstract

A model of respiratory distress has been developed using sheep in which an isolated lobar injury is induced by infusion of oleic acid into a selected lobar artery. The directed insult permits acute and chronic phase study without the requirement of intensive pulmonary support. One hour after selective lobar injury the affected pulmonary venous oxygenation (Ppvo2) was reduced from greater than 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 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 both complete parenchymal replacement by fibrous tissue and those with minimal architectural distortion. The selective injury model offers a useful methodology for the evaluation of the effects of various agents on the acute and chronic response of the lung to injury.