A rheological model for studying the hematocrit dependence of red cell-red cell and red cell-protein interactions in blood 1

RBC-RBC and RBC-protein interactions are known as strongly influencing the rheological behaviour of blood. As (i) at physiological level in hematocrit these effects are imbricated and (ii) most of previous methods required experimental conditions more or less distant from the physiological ones, further analysis of rheological effects of these interactions seems needed. A new attempt is presented, which grounds on viscosity data processing in terms of an “actual packing concentration” (APC), as a structural parameter. At given hematocrit H and shear rate γ ˙ , the APC is the packing concentration which would be obtained if particles (aggregates or single ones) were packed without change in their actual state (i.e. the state they have at Hand γ ˙ values). Discussion of hematocrit dependence of low and high shear APCs in the cases of Whole Blood, Defibrinated Blood and Ringer Suspension of cells (from CHIEN et al’s viscosity data) allows one to postulate reasonable structural changes at critical hematocrits, noticely at a percolation like threshold. Relative importance of RBC aggregation and RBC deformation by crowding 1S then deduced.