Determination of yield point: methods and review.

The question whether blood exhibits pseudoelastic behavior i.e. if it behaves like a solid under negligible external forces, is of great theoretical interest for ths clarification of stasis phenomena in the microcirculation. The determination of yield point, that is the change from the solid to the fluid phase, was at first only of abstract scientific importance for blood. In the diagnosis and treatment of patients with flow anomalies this phenomenon is increasingly important, as numerous possibilities now exist to modify the flow behavior of blood by therapeutical changes of composition. Therefore it seems to be of high priority to review and discuss the numerous methods for the quantification of a yield shear stress.