Abstract
We compared the blood thixotropic/shear-thinning properties and the red blood cells’ (RBC) rheological properties between a group of patients with sickle cell anaemia (SS) and healthy individuals (AA). Blood thixotropy was determined by measuring blood viscosity with a capillary viscometer using a “loop” protocol: the shear rate started at 1 s−1 and increased progressively to 922 s−1 and then re-decreased to the initial shear rate. Measurements were performed at native haematocrit for the two groups and at 25% and 40% haematocrit for the AA and SS individuals, respectively. RBC deformability was determined by ektacytometry and RBC aggregation properties by laser backscatter versus time. AA at native haematocrit had higher blood thixotropic index than SS at native haematocrit and AA at 25% haematocrit. At 40% haematocrit, SS had higher blood thixotropic index than AA. While RBC deformability and aggregation were lower in SS than in AA, the strength of RBC aggregates was higher in the former population. Our results showed that 1) anaemia is the main modulator of blood thixtropy and 2) the low RBC deformability and high RBC aggregates strength cause higher blood thixotropy in SS patients than in AA individuals at 40% haematocrit, which could impact blood flow in certain vascular compartments.
Highlights
Blood is a non-newtonian fluid with visco-elastic, shear thinning and thixotropic properties
Franco et al [3] reported increased blood thixotropy in patients with Gaucher Disease. In both cases the increased blood thixotropy resulted from enhanced red blood cells’ (RBC) aggregation [2, 3], and was suspected to participate in the cardiovascular and microcirculatory disorders observed in these two diseases
The present study provides information about the blood thixotropic and shearthinning properties determined at different haematocrits and red blood cells’ (RBC) rheological properties of SS patients compared to healthy individuals (AA)
Summary
Blood is a non-newtonian fluid with visco-elastic, shear thinning and thixotropic properties. A thixotropic fluid is a fluid whose viscosity is a function of the shearing stress, and of the previous history of motion within the fluid [1]. The viscosity usually decreases with the length of time the fluid has been in motion. Increased blood thixotropy has been reported in patients with coronary artery disease [2]. Franco et al [3] reported increased blood thixotropy in patients with Gaucher Disease. In both cases the increased blood thixotropy resulted from enhanced RBC aggregation [2, 3], and was suspected to participate in the cardiovascular and microcirculatory disorders observed in these two diseases
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