Determination of Circulating Pulmonary Blood Volume in Dogs by an Arteriovenous Dye Equilibration Method

Abstract

Tlie "equilibration" method introduced by Bradley to measure circulating "splanchnic blood volume" has been applied to the estimation of "pulmonary blood volume." The theoretic and practical aspects of the method are analyzed. Values for circulating "pulmonary blood volume" determined in anesthetized dogs were not significantly different from values obtained by the "mean circulation time output" method and were significantly greater than those determined by the "slope output" method. When experimental conditions were varied, relatively parallel changes were recorded by the three methods. It is believed that the "equilibration" method is a valid one for estimating circulating "pulmonary blood volume."

Estimation of Venous Blood Volume in the Dog by the Indicator-Dilution Method

“…Our finding that the average cardiopulmonary blood volume in the dog is equivalent to 34 per cent of the total blood volume is in agreement with the measurements of Rabinowitz and Rapaport, 5 and of Nahas, Visscher, Mather, Haddy, and Warner. 6 The limited information available on the volume of the larger veins is compatible with our finding of 18 per cent of total blood volume.…”

The Pulmonary Blood Volume in Mitral Stenosis 1

“…Coincident with injection, sampling was begun simultaneously from the pulmonary artery and one brachial artery by means of a constant suction pump in a manner previously described (9). Multiple samples were collected continuously at 30 to 40-second intervals for 5 or 6 periods.…”

“…Cardiac output was determined by both the direct Fick and by the indicator dilution method of Stewart as modified by Hamilton (10,12). "Pulmonary" blood volume was determined as the sum of pulmonary plasma and red cell volumes by the Stewart-Hamilton method, as follows: "Pulmonary" plasma volume Similarly, "pulmonary" blood volumes were calculated by the equilibration method of Bradley and his associates (8,9) At the same time, the red cell radioactivity was measured sufficiently long to insure less than a one per cent standard error. Under these analytical conditions, it was our feeling that one might well be able to measure the pulmonary blood volume in man with reasonable accuracy despite the relatively high flow to volume ratio.…”

“…It is true that an additional volume of large vessel blood contained in the right ventricle and right auricle which seems to be included in the volume yielded by the indicator dilution method, does not appear in the determination of the pulmonary hematocrit by the arteriovenous equilibration method. However, this in itself seems incapable of altering the mean to this extent, and other limitations and assumptions in both methods, which have been detailed elsewhere (8,9,13), may also play a role. In any case, the ability to demonstrate by both these methods that pulmonary hematocrit was less than large vessel hematocrit is of considerable significance, for both methods measure a huge amount of large vessel blood as contrasted to the actual amount of blood in small vessels.…”

“…The present study was undertaken in an attempt to re-evaluate this problem by correlating the "pulmonary" blood volume with other variables measured by right heart catheterization; pulmonary blood volume was determined by the Bradley arteriovenous equilibration method (8,9) as well as by the traditional Stewart-Hamilton method (10,11,12) and the simultaneous use of both a plasma tag, Evans Blue dye and chromium"' tagged red cells.…”