Pressure-Volume Characteristics and Stress Relaxation in the Pulmonary Vascular Bed of the Dog

Abstract

Using an isolated lung prepn., the pressure-volume relationship of the pulmonary vascular bed and left auricle was studied. For any given volume of blood in the system the pressure is higher while blood volume is increasing than while it is decreasing. This is presumably due to stress relaxation which begins to occur at levels above 15-30 mm. Hg and becomes progressively more pronounced as the pressure is increased. The left auricle-pulmonary vein prepn., with leakage excluded, shows the same characteristics. The pressure-volume curve of the pulmonary vascular bed is the same at different temps. (30-39[degree]C ). These data confirm the theoretical pressure-volume curves of the pulmonary veins and left atrium.