Technological Advances in Blood Rheology

Abstract

The science of blood rheology (study of the flow and deformability of blood) is of increasing practical importance to the investigation of blood disorders. In diagnostic laboratories, rheological tests such as the erythrocyte sedimentation rate, zeta sedimentation ratio, and plasma viscosity are used to monitor patients with an acute-phase response of greater than 24 h duration. In sickle-cell anemia, new methods for measuring erythrocyte deformability can be used to investigate the pathogenesis of vaso-occlusion, to test potential anti-sickling drugs, and to monitor drug efficacy in clinical trials. Genetic defects in the structure of the red cell membrane can have rheological consequences, monitoring of which may be useful for diagnosis. Rheological analysis of red cells infected by Plasmodium falciparum has indicated that their abnormal flow behavior may be an important pathological factor in malaria. Finally, the flow behavior of white blood cells, particularly neutrophils, is also important, as these cells, once activated, have the potential to occlude microvessels. The authors have reviewed the laboratory methodology and clinical applications that have led to recent advances in these aspects of blood rheology.

Effects of dietary supplementation of saturated fatty acids and of n−6 or n−3 polyunsaturated fatty acids on plasma and red blood cell membrane phospholipids and deformability in weanling guinea pigs

“…Furthermore, the cholesterol content in membranes, which was not measured in our study, may influence membrane lipid fluidity. However, the parameter lipid fluidity characterizes molecular motion, not the mechanical behavior of the entire membrane, as exemplified by deformation (35). We showed that incorporation of saturated fatty acids (lipid A from bacteria) in RBC membranes of humans resulted in decreased RBC deformation (36,37), whereas feeding rats with DHA-rich diet improved RBC deformation without influencing the cholesterol/phospholipid ratio (19).…”

Untitled

“…The results of the present study were obtained using normal erythrocytes that were dehydrated in vitro using hypertonic buffer or ionophores and then filtered through 5 m diameter pores, the degree of the rheological stress induced in these experiments was non-physiological, although the types of stress were relevant to clinical disorders 12,13,28 . Therefore care must be taken when extrapolating the present findings to clinical studies.…”

“…Erythrocyte filterability measured in the present study as an index of filteration (IF) through 5 m pore diameter polycarbonate membranes, is a popular method for measuring erythrocyte deformability 12 . This method was found to be more sensitive to changes in erythrocyte MCHC than to MCV 14 , thus reflecting changes in erythrocyte water and cation content.…”

“…This Deformability is the basic rheological property of the erythrocyte. The high deformability of the normal human erythrocyte is a consequence of its low cytoplasmic viscosity, its high ratio of membrane surface area to cell volume and its viscoelastic cell membrane 12 . Loss of erythrocyte deformability may arise from impairement of any one, or a combination of these properties.…”

“…As overhydration of the erythrocyte can decrease the ratio of membrane surface area to cell volume, hypotonic stress of erythrocytes measured as erythrocyte osmotic fragility is also considered rheologically important 13 . Erythrocyte aggregation measured as erythrocyte sedimentation rate (ESR) is another widely used rheological test that monitors whole blood viscosity 12 .…”