Methods in blood rheology – from theoretical and experimental approach to clinical applications

A great variety of instruments, methods and models to study hemorheological parameters under conditions close to physiological are currently used. An overview of the factors, determining hemorheological properties and models, describing the relationship between shear stresses, shear rate, viscosity and hematocrit is presented. Time dependent properties – blood thixotropy and viscoelasticity and the influence of the inner structure on the blood flow has been described. A method, based on dielectric properties of dispersed systems in Couette viscometric blood flow, previously described [3,4] and applied to investigate the kinetics of RBC aggregation has been presented. The experimental relationships show that the human blood conductivity is time, shear rate and hematocrit dependent under steady and transient flow conditions. The results show that valuable information could be received about the mechanical properties of blood, in particular about the kinetics of “rouleaux formation” and that this technique may be used to clarify the mechanism of dynamics of RBC aggregates. Thus a method, based on dielectric properties of dispersed systems in Couette viscometric blood flow could be applied to investigate the kinetics of RBC aggregation.