Background on non-invasive blood rheology Essay Example | Topics and Well Written Essays - 500 words

Background on non-invasive blood rheology - Essay Example (1) In rheology the viscosity of a Newtonian fluid remains constant as shear rate is proportional to shear stress. However, in a non-Newtonian fluid viscosity is not constant as shear rate and shear stress are not proportional. The plasma constituent of blood is a Newtonian fluid, while whole blood is a non-Newtonian fluid, because orientation and deformation of red blood cells result in changes of apparent viscosity at different shear rates. It is this aspect of blood and its constituents that relevant to clinical investigations. (1) Sedimentation is the rate at which the red blood cells separate from the blood plasma over time in clinical testing of blood. It is better known as erythrocyte sedimentation rate (ESR), and high ESR is indicative of inflammation in the human body. Normal values are 5-15mm/hr, depending on the technique employed. Viscosity may be considered as the internal resistance of blood to shear forces. The normal values for blood viscosity vary depending upon the techniques employed in its evaluation. Higher blood viscosity is indicative of inflammation. Blood viscosity for a given shear value is dependent on the hematocrit value, plasma viscosity, ESR and rheological properties. The higher these values over normal, the higher are the blood viscosity rates over normal. (1). Changes in blood composition occur due to several diseases and conditions, which include anemia, malnutrition and dehydration, leukemia, heart failure, kidney disease, rheumatoid arthritis, and blood loss due to trauma or surgery. Several blood tests play a role in the determination of these diseases and conditions and in tracking the efficiency of the intervention strategies. This is reason why blood tests are the normal experience during the initial clinical investigations and during the course of the treatment. (1). Anemia is a common condition that results from the deficiency in red blood cells, which is