Cardiac dysfunction during acute lung injury induced by oleic acid in dogs

Circulatory abnormalities are common during the adult respiratory distress syndrome and contribute importantly to the high mortality seen with this illness, but what causes them is not well characterized. Oleic acid-induced acute lung injury is an experimental model of the human syndrome in which hemodynamic changes are also common. To characterize a possible link between lung injury and cardiac dysfunction in this model, we evaluated cardiac function in mongrel dogs after oleic acid administration. Stroke volume index decreased, the radionuclide ventriculographically determined ejection fraction decreased, and end-diastolic volume increased after oleic acid. These results suggested a decrease in myocardial contractility, a conclusion confirmed when other experiments demonstrated a consistent rightward displacement of the end-systolic pressure-diameter relationship after oleic acid. Histologic examination of the myocardium showed little evidence of vascular injury, and myocardial tissue wet-to-dry weight ratios were normal. Thus, although the pulmonary effects of oleic acid are due to microvascular injury, similar mechanisms are not responsible for the depression in myocardial contractility.