The Measurement of the Circulating Red Cell Volume by Means of Two Radioactive Isotopes of Iron 1

Abstract

Measurement of blood volume, both of its plasma and red cell portion, is a useful tool in clinical and experimental investigation. It provides basic data for the assay of the total quantity of individual blood components, as well as for the evaluation of observed hemodynamic changes in acute or chronic disturbances of the circulation. Blood volume determinations have proved of value in the study of congestive heart failure, the anemias, thyroid disorders, renal disease, and pregnancy; and they have been particularly useful-during the recent war years in the study of hemorrhage, burns and shock, and in the development of blood substitutes and blood cell preservatives.It seems reasonable to state that the dye method (1, 2) measures the circulating plasma volume with a high degree of accuracy both in normal and pathologic states, and in many clinical and experimentally induced abnormal circulatory conditions. This view appears to be shared by investigators who have had firsthand experience with the technique (3, 4).Perhaps the best experimental evidence that the method accurately measures changes in plasma volume was obtained in a series of experiments in which the increase in plasma volume following the intravenous injection of concentrated (25 per cent) human serum albumin was measured (5).The osmotic equivalent of 1 gram of this protein was found by Scatchard et al (6) to be 18 ml. of H20; the average increase in plasma volume in 11 male human subjects was 17.4 ml. of H20 (5) per gram of albumin.

Circulating Red Cell Volume Measured Simultaneously by the Radioactive Iron and Dye Methods 1

“…Total blood volume and erythrocyte volume were calculated from the determined plasma volume and the venous hematocrit. Red cell volume was determined by the radioactive iron method (25) The plasma volume (Vpd), venous hematocrit, whole blood (Vwpd) and red cell volume (Vrpd) calculated from the plasma volume and hematocrit, the red cell volume determined by radio-iron (Vrr), and the sum of the plasma volume and radio-iron cell volume (Vwdr) are given in Table II Figure 1 for the normal males, and in pression of the relationship of circulating cell vol- Figure 2 for the dogs.…”

“…They found the cell volume measured by the injection of tagged cells consistently lower than the dye plasma cell volume, by as much as from 10 to 40 per cent, averaging 25 per cent.…”

The Post-Transfusion Survival of Preserved Human Erythrocytes Stored As, Whole Blood or in Resuspension, After Removal of Plasma, by Means of Two Isotopes of Radioactive Iron 1

“…The method used in these studies for measuring posttransfusion survival of stored cells by means of 2 radioactive isotopes of iron has been described in previous communications (38, 39,40 …”

“…In vivo SURVIVAL OF STORED RED CELLS: RADIO-IRON Recipient pre-transfusion red cell volume was directly measured by transfusion of fresh red cells tagged with Fe5' (39), or by the dye method (41). The radioactive blood used was drawn from the donors into ACD-1 from 1 to 48 hours before it was injected, and was refrigerated from the time of the bleeding to shortly before administration.…”

The Use of Two Radioactive Isotopes of Iron in Tracer Studies of Erythrocytes 1

“…The utilization of radio-iron, either when given as a ferric salt or as dissolved hemoglobin, or resulting from the postinfusion breakdown of tagged red cells, as well as the application of the "double tracer" technique to a wide variety of experimental and clinical studies will be discussed in subsequent communications (13,14).…”