(221f) Flow Analysis of Human Blood Using a Compact-Sized Falling Needle Rheometer (FNR) and Correlation Using Modified Constitution Equation Based on Herschel-Bulkley Model

In recent years, Blood viscosity considered to be important from the viewpoint of prevention and treatment of cardiovascular diseases in a medical field.

Human blood contains both cellular components and plasma components.

Measurement of blood viscosity have many difficalties due to the coagulation aggregation characteristics of blood and complicated flow characteristics by red blood cell. however, a problem that the amount of high accuracy viscosity data is insufficient. Therefore, our laboratory has been developing a small type of viscometer: Falling Needle Rheometer (FNR) which can measure blood viscosity with high accuracy. Although FNR has been used to measure various specimens such as pigs, sheep, rabbits, horses and humans up to now, the number of specimens for examining human blood flow characteristics has been small and insufficient. In addition, there has been no method that represents a continuous equation for blood viscosity measured using FNR until now. In this study, using the flow analysis values measured using FNR, we created a shear rate-apparent viscosity model equation to estimate viscosity for a certain shear rate.

There are various model equations, such as a Newton model and a Power law model. Among them, the application of Casson model and Herschel-Bulkley model is mainly studied for blood.

There is a problem that the available shear rate region is limited because there is a region where the model equation and the actual blood viscosity do not correspond sufficiently in a specific shear rate region.

Although the Herschel-Bulkley model shows relatively high fitting accuracy in the low shear rate region, there is a problem that the viscosity value does not become constant but decreases in the high shear rate region. Furthermore, the Casson model shows high fitting accuracy in the high shear rate region but tends to be calculated to be lower than the original viscosity value in the low shear rate region. So, this time based on the Herschel-Bulkley model (HB model).

In blood viscosity measurement, blood was provided from as many as 104 healthy subjects as specimens.As mentioned above, it succeeded in creating a database in blood viscosity of 104 healthy persons using FNR.Moreover, it succeeded in expressing the flow analysis value in the form of a continuous equation in the mHB model.In the future, it is thought that this model equation can contribute to analysis considering non-Newtonian fluid of human blood by incorporating numerical flow analysis (CFD analysis).