A Theoretical Analysis of the Effects of Varying Fibrinogen Concentration and Haematocrit on the Flow Characteristics of Blood in Cylindrical Tubes

The viscosity: shear rate relationship of whole blood is shown to be described to a good approximation by a bi-linear plot on log: log axes. This has allowed an analytical solution to be obtained which gives a full description of the flow properties of blood in rigid tubes of a size where the Fahraeus-Lindqvist effect is minimal. As a result the profound effects that changing haematocrit has on blood flow in such tubes can be quantitated. The analysis also shows that in similar circumstances altering fibrinogen concentration is of rheological significance only at flow rates below the normal physiological range.