Influence of acute pulmonary vascular congestion on recoiling force of excised cats' lung

Abstract

The effects of acute reversible pulmonary vascular congestion on the elastic behavior of excised cats' lungs were studied in 10 preparations. Measurements were made of changes in airway pressure at constantly held lung volumes over a wide range of deflation. To achieve vascular congestion left atrial pressure was raised to 20 and 30 cm H₂O. Two effects were noted; one was that the slope of the volume-pressure relations of the lungs was slightly reduced at all levels of deflation, the other, the effect of vascular congestion on the recoiling force of the lungs was a function of the volume of the lungs at which congestion was induced. At large volumes (airway pressures of 5 cm H₂O or more) recoiling force was increased; at intermediate volumes (airway pressures of 2.5 and 3 cm H₂O) the change was negligible and, at smaller volumes, it was reduced in a manner consistent with the early work of von Basch. The findings suggest that there is a volume of the lungs, or perhaps a narrow range of volume, at which the lungs and blood vessels exert least mechanical stress on each other. This volume is believed to lie close to that in which tidal breathing occurs. Note: (With the Technical Assistance of Elcanor Gotz) Submitted on April 17, 1959