Red blood cell filterability and occlusive arterial disease

Abstract

In 1976 Ehrly and co-workers as well as Reid and co-workers investigated the filterability of blood from patients with chronic occlusive vascular diseases. Using micropore filters there was a markedly reduced filterability in spite of differences in the filterability techniques as filter type, hydrostatic pressure and others.

The results were explained by an increased ridgidity of red cells which increase the resistance to flow through the filter pores. These findings where discussed as one of the pathophysiological mechanisms of chronic occlusive arterial diseases, but brought up a number of questions such as the mechanism of the reduced filterability and the significance of an impaired deformability of red cells in vivo. Another question is if the impaired filterability of blood is the cause or the consequence of the underlying disease.

If we consider the red cell deformability to be an important factor for the pathophysiology of vascular diseases, it seems clear that not only the mechanical property of the less deformable red cell in the capillary will be most important, but also rigid red cell as a cause for an inhomogenous blood flow in the microcirculation (microcirculatory blood maldistribution).

From the therapeutic point of view it seems important to know the mechanism which leads to an impaired flexibility of red cells, so, for example, a low ATP-content in the cells, hypermolarity or acidosis of blood.

In vitro tests, like filtration of patients blood through micropore filters, may indicate the value of drugs said to improve the deformability of red cells. More sophisticated methods like the measurement of the oxygen tension of the muscle tissue can give us an answer as to whether an improvement of the deformability of red cells also leads to an improvement of the tissue supply.

Key Words:

• occlusive arterial disease
• erythrocyte deformability
• tissue oxygen pressure
• microcirculatory blood maldistribution