Whole blood reduces viscosity, whole blood viscosity decreases, plasma viscosity increases, why?

In the blood viscosity test, in addition to the direct determination of whole blood viscosity and plasma viscosity, the reduced viscosity of whole blood is introduced. Because the blood viscosity is affected by the hematocrit, and the red blood cells are the most important factor affecting the viscosity of whole blood, under various shear rates, the viscosity of whole blood increases with the increase of HCT (hematocrit), and the apparent viscosity of whole blood increases exponentially with the increase of HCT at the same shear rate, and its apparent viscosity decreases with the increase of shear rate at the same shear rate. In order to eliminate the effect of HCT and facilitate the comparison of viscosity of different blood samples, the concept of reduced viscosity (RV) of whole blood was introduced.

Whole blood reducing viscosity refers to the whole blood viscosity value when the hematocrit is 1, also known as the unit hematocrit viscosity, or defined as the contribution of the unit hematocrit to the relative viscosity of whole blood. In this way, the blood viscosity is corrected to the unit HCT for comparison, indicating the magnitude of the effect on the blood viscosity due to changes in the rheological properties of the red blood cells themselves (rather than due to changes in the number of red blood cells).

2 If the viscosity of whole blood is high and the reduced viscosity of whole blood is normal, it means that the high HCT (blood thickness) causes high blood viscosity, but the rheological properties of RBC itself are not abnormal.

3 If the viscosity of whole blood is normal and the reduced viscosity of whole blood is high, it means that HCT is low (blood thin) but RBC itself has abnormal flow edge properties (contributes too much to viscosity), indicating that the viscosity of whole blood is still high, which also has reference significance.

4 If the viscosity of whole blood and the reduced viscosity of whole blood are normal, the blood viscosity is normal.

This can be seen in many diseases.

It can also be seen in normal people.

The situation is treated on a case-by-case basis.

Whole blood viscosity is one of the indicators that reflect the fluidity and coagulation of blood.

Whole blood viscosity is reduced in certain anaemic disorders, slow-dissipating gastrointestinal bleeding, epistaxis, uterine bleeding, hemorrhagic shock, intracerebral hemorrhage, and pregnancy and menstruation in women.

Plasma specific viscosity refers to the ratio of whole blood viscosity to water. The increase is mainly affected by plasma composition, and it is seen in elevated plasma proteins, tumors, rheumatism, tuberculosis, hyperlipidemia, diabetes, and autoimmune diseases. Decreases can be seen in kidney disease, chronic malnutrition.

The erythrocyte stiffness index reflects the deformability of the red blood cells, and a large red blood cell stiffness index indicates that the red blood cells are stiff and have poor deformability. The deformation of red blood cells is extremely important for blood circulation in tiny blood vessels.

The erythrocyte deformation index mainly depends on the geometry of the red plum cell, the structure of the membrane, and the internal viscosity of the erythrocyte. Decreased red blood cell deformation is common in hemolytic anemia, myocardial infarction, hyperlipidemia, hypertension, diabetes, malignancy, cerebral thrombosis, etc.

Whole blood viscosity refers to the resistance formed by friction between two adjacent layers of parallel fluid as blood flows. Whole blood viscosity is a combination of serum viscosity, hematocrit, red blood cell deformability and aggregation ability, platelet and leukocyte rheological properties. In addition, blood viscosity is also affected by blood physical and chemical properties (such as temperature, acidity, plasma osmolality, etc.), vascular factors, etc.

Blood viscosity is also related to blood perfusion, so there are two types of whole blood viscosity: high shear and low shear. High shear viscosity reflects the deformation ability of red blood cells, and low deformation ability leads to high blood viscosity; Low shear viscosity reflects the ability of red blood cells to aggregate, and red blood cells clump together and blood viscosity increases. Whole blood viscosity measurement can provide a reference for the diagnosis, treatment and prevention of many clinical diseases, especially for the diagnosis, treatment and prevention of thrombotic states and thrombotic diseases.