Computation of the Coefficients of the Power law model for Whole Blood and Their Correlation with Blood Parameters

Mohamed A Elblbesy,Abdelrahman T Hereba

doi:10.5539/apr.v8n2p1

Abstract

This study introduces a quantitative analysis of the coefficients of the power law model, which is used to describe the non-Newtonian behavior of blood. Twenty blood samples from healthy donors were used to measure the whole blood viscosity under different values of the shear rates, which are between 2.25 and 450.0 s-1. The shear rate viscosity curves were used to calculate n (flow index) and m (the consistency of the fluid) according to the power law model. Strong correlations (R2 &gt; 0.5) between m and the hematocrit (HCT %), hemoglobin (Hb), erythrocytes count (RBC), mean corpuscle volume (MCV), and mean corpuscle hemoglobin concentration (MCHC) were obtained. Strong correlations (R2 &gt; 0.5) between n and the RBC, MCV, and MCHC were achieved. The relation obtained between the power law coefficients and the blood parameters in the present investigation provides new parameters that can be used to evaluate the flow state of blood besides blood viscosity. In addition, these parameters may be used to examine blood under pathological conditions, representing a new tool for the diagnosis of blood abnormal conditions.

Highlights

IntroductionBlood is a heterogeneous multi-phase mixture of solid corpuscles (red blood cells, white blood cells, and platelets) suspended in liquid plasma, which is an aqueous solution of proteins, organic molecules, and minerals
Blood is a heterogeneous multi-phase mixture of solid corpuscles suspended in liquid plasma, which is an aqueous solution of proteins, organic molecules, and minerals
In smaller vessels, or in some disease conditions, the presence of cell induces a low shear rate and whole blood exhibits remarkable non-Newtonian characteristics, such as shear-thinning viscosity, thixotropy, viscoelasticity and possibly a yield stress. This is largely due to the behavior of red blood cells (RBCs), namely, their ability to aggregate into microstructures at low shear rates, their deformability into an infinite variety of shapes without changing volume and their tendency to align with the flow field at high shear rates (Chien et al, 1970; Schmid-Schöenbein & Wells, 1969)

Summary

Introduction

Blood is a heterogeneous multi-phase mixture of solid corpuscles (red blood cells, white blood cells, and platelets) suspended in liquid plasma, which is an aqueous solution of proteins, organic molecules, and minerals. In smaller vessels, or in some disease conditions, the presence of cell induces a low shear rate and whole blood exhibits remarkable non-Newtonian characteristics, such as shear-thinning viscosity, thixotropy, viscoelasticity and possibly a yield stress. This is largely due to the behavior of RBCs, namely, their ability to aggregate into microstructures (rouleau) at low shear rates, their deformability into an infinite variety of shapes without changing volume and their tendency to align with the flow field at high shear rates (Chien et al, 1970; Schmid-Schöenbein & Wells, 1969). An understanding of the coupling between the blood composition and the physical properties of blood is essential to develop suitable constitutive models to describe blood behavior (see the recent reviews) (Robertson et al, 2009; Robertson et al, 2008)

Methods

Results

Discussion

Conclusion