Pathophysiological patterns of resolution from acute oleic acid lung injury in the dog

Lungs of mongrel dogs with permanent tracheostomies and implanted systemic pulmonary arterial catheters were injured by intravenous infusion of oleic acid (0.09 mg/kg). Injury resulted in extensive, multifocal, and nonrandomly distributed lung damage. Awake dogs were studied during a control period and 1, 4, and 7 days following injection of oleic acid. Standard gas exchange measurements, the inert gas elimination technique, and subsegmental bronchoalveolar lavage (BAL) were used. Five oleic acid dogs and two saline control dogs were killed after each study period for morphological evaluation. Control dogs did not develop significant gas exchange abnormalities but did have localized inflammatory reactions at the lavage site. The oleic acid dogs developed significant shunt at day 1 with resolution of shunt by day 7. The multifocal sites of oleic acid injury were virtually identical in appearance at a given time interval; they consisted of alveolar cell necrosis with varying amounts of hemorrhagic inflammatory exudation at day 1 followed by a proliferative reparative reaction resulting in substantial restoration of alveolar structure at day 7. BAL showed a suppurative inflammatory response with hemorrhage on day 1 and an increased number of macrophages by day 7. The oleic acid model of acute diffuse lung injury demonstrates several pathophysiological alterations that could be compared with pathomorphological changes during the acute injury phase and during the subsequent reparative phase.