Stable and reproducible porcine model of acute lung injury induced by oleic acid

Background and Methods: Previous studies on acute lung injury induced with oleic acid did not attempt to limit the influence of secondary changes on pulmonary circulation, and cardiopulmonary variable data were only collected and processed intermittently. Our study was designed to continuously monitor the following variables in five swine:systemic and pulmonary pressure; mixed venous oxygen saturation (SV̄O₂) and arterial oxygen saturation (SaO₂); minute oxygen consumption and CO₂ production before, during, and for 4 hr after the infusion of oleic acid. A personal computer was programmed to produce 20-sec updates of deadspace ratio (VD/VT), venous admixture (Q̇sp/Q̇t), pulmonary (PVR) and systemic vascular resistance (SVR), and cardiac output (Q̇t) from these data. Results: During the oleic acid infusion, there were increases in PVR, SVR, heart rate (HR), mean pulmonary arterial pressure (MPAP), Q̇sp/Q̇t, and VD/VT, and a decrease in Q̇t, SaO₂, and S̄vO₂. Thirty minutes after the oleic acid infusion, there was a further increase in HR, Q̇sp/Q̇t, and VD/VT, while MPAP, PVR, and SVR gradually decreased to pre-oleic acid infusion levels. No further decrease in SaO₂, S̄vO₂, and Q̇t was observed during that time. After the 30-min period, there was no further change in the cardiopulmonary variables. Conclusion: Our method of continuous monitoring was able to demonstrate in swine both the dynamic changes during, and stability after, the oleic acid infusion.