• The ESR of sickle cell blood was studied with the use of Wintrobe sedimentation tubes. The hematocrit values were varied by removal or addition of autologous plasma, and the PO2 readings of blood samples were altered by a rotary-type tonometer. The results indicate that the ESR of sickle cell blood is not only a function of the Hct reading but also a function of PO2 . The influence of PO2 on the ESR was attributable to changes in the degree of RBC aggregation, which was quantified for sickle cell blood at different PO2 readings by viscometry. The viscometric aggregation index (VAI) was calculated from viscosity values at shear rates of 208 s-1 (ηH) and 0.05 s-1 (ηL) as follows:
VAI = (ηL − ηH)/ηH. The changes in RBC aggregation by variations of PO2 can be explained by alterations of cell deformability. Deoxygenation results in a reduction in cell deformability, which in turn inhibits RBC aggregation.
Jan K, Usami S, Smith JA. Influence of Oxygen Tension and Hematocrit Reading on ESRs of Sickle Cells: Role of RBC Aggregation. Arch Intern Med. 1981;141(13):1815–1818. doi:https://doi.org/10.1001/archinte.141.13.1815
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