Year: 1953
Type: article
Abstract: Most observers have found that when circu-lating red cell volume is deduced from measure-ment of plasma volume and venous hematocrit a higher value is obtained than when the red cell volume is measured directly. It is widely believed that this is because the proportion of red cells in the blood in large vessels is higher than that in the body as a whole and various correction factors have been proposed. Some confusion arises be-cause the venous hematocrit must be corrected on two accounts: firstly because, under standard con-ditions of centrifugation, some plasma is trapped in the red cell column of the hematocrit and thus the uncorrected reading over-estimates the pro-portion of red cells in the sample; when this cor-rection has been applied one may speak of the "true " venous hematocrit. Secondly, this cor-rected venous hematocrit value still over-estimates the proportion of red cells in the circulating blood as a whole and must be multiplied by a factor of approximately 0.9 to give an estimate of "body hematocrit. " Although these concepts are ac-cepted by the majority of investigators, the precise rtobody hematocritvalue of the ratvo u hematocrit is in doubt; venous hematocrit moreover it has been suggested that the ratio may be inconstant so that it cannot safely be used to deduce blood volume from an estimate of either red cell volume or plasma volume. Accordingly, it is generally held that the only reliable estimates of total blood volume are those based on separate measurements of both red cell volume and plasma volume. If, in fact, the body/venous hematocrit ratio ap-peared to be inconstant, the inconstancy could
DOI: 10.1172/jci102859
Authors: H. Chaplin, P. L. Mollison, H. Vetter
Institution: Medical Research Council
Language: English
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2164003699