[Filtration-absorption function of the lungs during hemodynamic stress in the pulmonary circulation]

Abstract

The transcapillary fluid exchange in the lung during elevation of the pulmonary venous pressure (PVP) was studied in cats. The weighing technique in vivo for a lung lobe, the comparison of the hematocrit of pulmonary arterial and venous blood, and the measurement of the outflow from the lung lobe at constant volume perfusion were used for the estimation of the filtration rate. The latter was not linearly related to PVP. Capillary filtration coefficient was about 0.040-0.055 ml/min/100 g tissue/mm Hg during the PVP rise by 5-10 mm Hg, and about 0.068-0.087 at PVP raised by 20-25 mm Hg. Under conditions of the open chest, the fluid accumulation was observed in the extravascular compartment of the lung even after relatively small and short PVP elevations.