Quantification of blood viscosity using power law model in cerebrovascular accidents and high risk controls

Present work concerns quantitative analysis of parameters that affect apparent blood viscosity at different low shear rates in acute cerebrovascular accidents. Viscosity profile of a large number of blood samples from thromboembolic stroke cases and age and sex matched healthy and hypertensive as well as diabetic controls were studied which confirmed non-Newtonian power law behaviour of blood. The importance of power law parameters namely non-Newtonian behaviour index “n” and flow consistency index “k” is discussed. Other apparent blood viscosity parameters such as, red cell filterability, red cell rigidity, hematocrit, plasma viscosity and biochemical parameters are evaluated and discussed. The cumulative effect of these parameters did not appear in terms of elevated whole blood viscosity in acute cases as compared to healthy controls since hematocrit value was on the lower side of the normal range. The whole blood viscosity in acute cases at any of the seven shear rates selected, was not significantly different from healthy controls. However power law parameters are shown to reveal the difference of apparent blood viscosity between acute stroke and controls. Hence the power law parameters may be considered a better tool to understand the significance of apparent blood viscosity in health and disease.