Red Cell and Plasma Volumes (Circulating and Total) as Determined by Radio Iron and by Dye

Abstract

1. Application of the principles of hydrodynamics to the problem of blood flow and blood volume indicates that the calculation of blood volume and cell volume from the venous hematocrit and plasma volume (as determined by the dye method) is subject to considerable error. 2. This conclusion is borne out by determinations of total cell volume by viviperfusion and with the use of radioactive iron tagged erythrocytes, which have shown the erythrocyte volume to be only 70 to 75 per cent of the volume indicated by the previously mentioned calculations. 3. The average hematocrit of the entire vascular system is considerably lower than the hematocrit of the large vessels, and the cell-plasma ratio of the smaller vessels is still less. 4. In the dog there are no considerable stores of immobilized erythrocytes, and the total erythrocyte volume and circulating erythrocyte volume are identical. 5. The "rapidly circulating blood volume" can be determined by dividing the erythrocyte volume by the venous hematocrit, and is found to be considerably less than the total blood volume. 6. The concept of the "rapidly circulating plasma volume" is introduced, and it is found to be approximately 80 per cent of the total plasma volume. 7. The volume of plasma in the peripheral, cell free, sluggishly moving plasma films, plus that contained in small vessels in which no red cells are present, is also determined and found to be approximately 20 per cent of the entire plasma volume. 8. The existence and magnitude of these fractions of the blood plasma volume should receive consideration in studies of blood flow and blood volume.

Blood Volume Alterations in Congestive Heart Failure

“…In four of the subjects (Nos. 11,17,25,26) there was an increase in total blood volume following therapy of heart failure. However, in one of these (No.…”

“…According to presently accepted concepts, the total body relative cell volume, RBC volume RBC volume + plasma volume' is appreciably lower than the relative cell volume of the blood withdrawn from the large vessels (hematocrit value) (8)(9)(10)(11)(12)(13)(14)(15)(16), and the ratio between these two is not necessarily constant (17). It is, therefore, theoretically possible for total erythrocyte volume and venous hematocrit value to remain unchanged in the presence of a significant increase in plasma volume, if the ratio, total body relative cell volume venous hematocrit value decreases.…”

The in Vitro Preservation and Post-Transfusion Survival of Stored Blood 1

“…The cell volume so determined was corrected to compensate for the error introduced by unequal distribution of erythrocytes and plasma throughout the vascular system (29).…”

The Distribution of Red Cells and Plasma in Large and Minute Vessels of the Normal Dog, Determined by Radioactive Isotopes of Iron and Iodine 1

“…Direct evidence lies in the fact that the circulating red cell volume determined by radioactive iron is consistently less than when measured at the same time in the same subject by the dye-plasma-hematocrit method in dogs (2) and in humans (1). Equivocal evidence is the finding of either larger or smaller red cell volume by the carbon monoxide than by the dye technique (3).…”