Correlation between cardiopulmonary changes and severity of acute lung injury in dogs

In an attempt to determine the physiologic parameters that best correlate with severity of lung edema (wet/dry [W/D] weight), we serially monitored multiple cardiopulmonary hemodynamics, airway pressure, and blood gases on both 100% oxygen and room air after graded infusions of oleic acid (OA) in dogs. We found significant increases in the intrapulmonary shunt fraction (Qsp/Qt), mean pulmonary arterial pressure (MPAP), pulmonary (PVR) and systemic vascular resistance (SVR), alveolar-arterial PO2 difference (P[A-a] O2), and peak airway pressure (Paw), but decreases in PaO2 and pH. These cardiopulmonary hemodynamic changes were similar to those found in adult respiratory distress syndrome (ARDS). This study showed that Qsp/Qt (r = .72, p less than .001), PaO2 (r = -.60, p less than .01), P(A-a)O2 (r = .55, p less than .01), pH (r = -.55, p less than .01), MPAP (r = .50, p less than .05) and Paw (r = .49, p less than .05) significantly correlated linearly with W/D. The significant correlation is not high enough clinically to predict the severity of acute permeability pulmonary edema considering only one parameter of cardiopulmonary hemodynamic change. Therefore, we propose the possible prediction of the severity of ARDS by considering all of the above hemodynamic changes together with Paw or dynamic compliance.