The Effect of Oleic Acid-Induced Pulmonary Edema on Pulmonary and Chest Wall Mechanics in Dogs1–3

Experimentally induced acute pulmonary edema causes changes in the pressure-(gas) volume characteristics of both the lungs and the chest wall. These changes consist of a decreased functional residual capacity and an increased recoil pressure for both lungs and chest wall at any given gas volume. However, with increased accumulation of liquid in the lungs, the gas becomes a relatively smaller component of intrathoracic lung volume. We used rib cage magnetometer signals as an index of chest plus lung volume, compared with lung gas volume as measured by helium dilution, in relation to transpulmonary and transthoracic pressures before and after induction of acute pulmonary edema by infusion of oleic acid in 7 dogs. After infusion of oleic acid, functional residual capacity (normalized for body weight) decreased from a mean ± SD of 32.9 ± 5.5 to 16.8 ± 3.0 ml/kg (p < 0.001), and both transpulmonary and transthoracic pressures were greater at any given volume above functional residual capacity, but rib cage mag...