The synergistic influence of the intravascular starling forces on pulmonary microvascular solute flux in human ARDS.

To assess the importance of the intravascular Starling forces on the pulmonary microvascular flux of solutes in ARDS, the clearance from blood to pulmonary edema fluid of a small-molecular-weight hydrophilic radiotracer, indium-111-DTPA, and a large-molecular-weight radiotracer, iodine-125-HSA, in patients with noncardiac pulmonary edema was measured. Since permeability changes of the pulmonary microvessels in ARDS are likely not homogeneous, the severity of the permeability lesion according to the magnitude of I-HSA flux was predefined. A significant positive correlation between the clearance of In-DTPA and the Pmv-pi mv gradient was found both in patients with a "moderate" (R2 = 0.46, P less than 0.01) and "severe" (R2 = 0.45 P less than 0.01) increase in microvascular permeability. The clearance of I-HSA from blood to edema fluid was also positively correlated with the Pmv and the Pmv-pi gradient. Therefore, even though ARDS is primarily characterized by a spectrum of change in permeability within the pulmonary microvasculature, the flux of both small- and large-molecular-weight solutes remains synergistically modulated by the measurable intravascular Starling forces.