Viscoelastic-thixotropy of blood

Abstract

It is well established that the rheological properties of blood depend on the shear rate of the flow. At low shear rate of around 1 sec⁻¹, blood exhibits the property of a viscoelastic fluid. As the shear rate increases progressively, the blood transforms to thixotropic, pseudoplastic and then Newtonian fluid. In the shear rate range up to approximately 1 sec⁻¹, blood behaves viscoelastic and thixotropic. This time dependent, strain dependent and shear rate dependent rheological behavior of blood has been demonstrated experimentally in the literature. In this work, a rheological equation is developed for the characterization of both viscoelastic and thixotropic properties of blood. The equation is based on the Huang model of thixotropic property incorporated into the viscous component of the relaxation modulus of the general Maxwell model. Experimental data of rheological hysteresis of blood at low shear rate obtained by Bureau, Healy, Bourgoin and Joly was used to test the validity of representation of data by the developed equation. Ten sets of hysteresis data were tested. They can be divided into two different studies. The first study compared normal blood from a health human subject and the pathological blood from a diabetic patient. The second study shows the effect of neuraminidase treatment on normal blood. The shear rate ranges of hysteresis loops are 0 to 0.12 sec⁻¹ and 0 to 1.02 sec⁻¹. Results show that our rheological equation gives excellent representations of 10 sets of hysteresis loops with diversified rheological behavior. Therefore the rheological parameters in the equation can be used to compare normal blood behavior with that of pathological and neuraminidase modified bloods. This method of parameter comparison may lead to the detection of serious pathological conditions and be further developed to a clinical test. The method may also monitor the effectiveness of drug treatment to a patient as the patients blood sample rheological parameters return to that of normal healthy human subjects.