The clinical relevance of the flow properties of blood cells.

In the recent years hemorheology has gained increasing interest in medicine and contributed to new understanding of the role of blood fluidity with regard to microcirculation especially in chronic occlusive vascular disease. Various hemorheologic factors have been uncovered as being of significance in physiologic and pathologic flow conditions. Primarily the deformability of red cells was in the center of interest and various devices mostly based on filtration systems, were introduced for the measuring of red cell's ability to deform. In the last few years the role of white cells came into play especially in conditions of low perfusion pressure in ischaemic areas. Since it is plausible that in capillaries white cells can hold up a very much larger number of red cells it is most likely that the rheological properties of white cells play a governing role in areas of ischaemia and infarction in respect of blood fluidity, flow and prognostic aspects. A new filtration device is now available which can distinguish between the resistance to flow of the rheologically predominant cell type of a suspension (initial filtration rate) and the number of rigid cells blocking the filter pores (clogging rate). Intensive studies will be necessary to clarify the rheological behaviour of the different types of white cells.