Internal Viscosity (Rigidity) of the Red Cell and Blood Viscosity Equation; Counteraction of Errors Due to Flow Instability of Plasma

Summary

The viscosity of blood depends on the apparent internal viscosity of the red cell, concentration of red cells and plasma viscosity as primary factors, and on aggregation of red cells. The blood viscosity equation based on these primary factors has been suggested: n_r = (1 - CkT) exp -2.5, in which T is the Taylor’s factor, and^rk the immobilized plasma on and between red cells. Problems arose in regard to determination of plasma viscosity which was much higher in rotational than in capillary viscometers; this is suggested to be due to flow instability and Taylor’s vortices in plasma. Term Tk, obtained from the blood viscosity equation, can be used to characterize rigidity of red cell in various diseases. Blood viscosity equation can be modified and reviewed from the viewpoint of various possible axial ratios of red cells and aggregates of red cells, as also from the viewpoint of low-shear-rate aggregation of red cells. Such a modified equation contains two additional coefficients, α and ß, and a subscript D indicating shear-rate dependence:

$${n_r} = {\left( {1 - {\alpha _D}C{K_D}{T_D}} \right)^{ - 2.5{\beta _D}}}$$