Blood volume determination as a function of hematocrit and mass in three preservative solutions and saline.

Accurate blood volume determination is useful both clinically and in research. In many instances, however, direct measurement of blood volume is impractical due to the risk of bacterial contamination. For this reason, mass is often used to estimate volume. The relationship between mass and volume (density) varies with different suspension solutions and hematocrits. In this paper, equations are derived to calculate volume as a function of hematocrit and mass for pooled red cells suspended in four solutions: CPD plasma (whole blood), additive solutions 1 and 3 (AS-1 and AS-3), and saline. To validate this approach, the actual versus predicted blood volumes in 10 individual blood samples suspended in either AS-1 or saline are compared. The equations predict the volume of blood to within 0.5% and 1.0% in samples with low/normal and high hematocrits (15% to 85%, respectively). Use of these equations allow for accurate and rapid conversion of mass to volume for these blood products.