Capillary Pressure in Right Heart Failure

Abstract

This investigation was undertaken to determine whether increased hydrostatic pressure within the capillaries was sufficient to explain the formation of edema in right heart failure without recourse to other factors such as anoxemia and increased permeability of the capillary membrane. Landis has determined the gradient of intra-capillary pressure in the capillary loops of the human skin by introducing a very fine glass cannula directly into the blood capillary. He determined the pressure in the arteriolar limb, at the venous end and near the summit of the loop. Landis'method, being a direct pressure measurement, is the most accurate method for measuring capillary blood pressure. The average pressure of 125 observations in the arteriolar limb was 32 mm. Hg, and the average pressure of 99 observations in the venous limb was 12 mm. Hg., according to Landis. The average pressure from 19 observations in the summit of the loop was 20 mm. Hg. We have made determinations of the capillary blood pressure on 6 normal adults, making use of Landis'method. The values for the arteriolar limb were 30-30-30-32-35-40, or an average of 33 mm. Hg. It was only possible to make observations of the blood pressure in the summit of the loop in 2 cases. Both of these gave values of 18 mm. Hg. Measurements of the hydrostatic pressure in the venous limb of the capillaries of 6 adults gave values of 15-12-12-12-12-10 or an average of 12 mm. Hg. These values agree extremely well with the average values obtained by Landis. The venous pressure as well as the capillary blood pressure in the venous end of the capillary loops were measured on 5 cases of right heart failure. Edema was present at the time the measurements were made.