Because it has direct and indirect action on lung tissue, oleic acid (OA) has been used experimentally as a model of fat embolism and acute respiratory distress syndrome (ARDS). The aim of this study was to describe acute and chronic pulmonary lesions induced in rats by intravenous injection of OA. Male Wistar rats were injected a 0.05 ml dose of OA. Groups of 5 animals were sacrificed 2, 24, 48 hours, and 5, 10, 30, and 90 days after injection. Diffuse alveolar edema, foci of intra-alveolar hemorrhage, and foci of ischemic necrosis were observed by light microscopic from 2 to 48 hours. At this period of time, severe endothelial injuries and type II alveolar cell lesions were observed on electron microscopy. After the fifth day, no injury was observed and discrete morphological sequelae were found. The lungs of the animals sacrificed at the thirtieth and ninetieth days were identical to those of the control groups. The present model allows animal to survive, being suitable for studies on fat embolism and on ARDS.

Keywords: Oleic acid. Fat embolism. Acute respiratory distress syndrome, ARDS. Experimental model.