On the basis of experimental viscometric determinations with human blood, the authors used a SISKO type relationship to describe the non-Newtonian rheological behaviour of blood : τ = ηp (η
$\dot{\gamma}$
+ α
$\dot{\gamma}$
1/2) where ηp is the plasma viscosity; η is a non-dimensional parameter equal to the relative viscosity of blood at infinite shear rate and α a constant characterizing the structure of blood. A good concordance was observed between the experimental blood viscosity and the theoretical values given by the relationship both for normal blood (n=133) and pathological samples (n=157). The model parameters were stable and well correlated with hematocrit and with RBC aggregation time measured by a laser back-scattering method. We tried equally to characterize pathological bloods by the model parameters. The statistic analysis showed that the mean values of α and η for some pathological samples (Kahler's disease, Waldenström's disease, Hypertension) were significantly different from normal values. It will be interesting to extend this study to other diseases, in particular to bloods in which the blood cells present altered rheological properties.
