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Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much oxygen is transported to tissues and organs.
Typical values for the viscosity of normal human plasma at 37 °C is 1.4 mN·s/m 2. [3] The viscosity of normal plasma varies with temperature in the same way as does that of its solvent water [4];a 3°C change in temperature in the physiological range (36.5°C to 39.5°C)reduces plasma viscosity by about 10%. [5]
Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes. For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3.
Although elevated whole blood viscosity is a better measure of hyperviscosity and more common and clinically important, serum viscosity and plasma viscosity are more frequently measured. [3] Normal plasma viscosity is between 1.4 and 1.8 centipoise while symptoms from hyperviscosity typically occur greater than 4 centipoise (about 4 times more ...
Typically, a higher hematocrit level signifies the blood sample's ability to transport oxygen, [19] which has led to reports that an "optimal hematocrit level" may exist. Optimal hematocrit levels have been studied through combinations of assays on blood sample's hematocrit itself, viscosity, and hemoglobin level. [19]
Some fluctuation or variation in blood pressure is normal. Variation in blood pressure that is significantly greater than the norm is known as labile hypertension and is associated with increased risk of cardiovascular disease [63] brain small vessel disease, [64] and dementia [65] independent of the average
The widely used [21] rule calculating normal maximum ESR values in adults (98% confidence limit) is given by a formula devised in 1983 from a study of ≈1000 individuals over the age of 20: [22] The normal values of ESR in men is age (in years) divided by 2; for women, the normal value is age (in years) plus 10, divided by 2.
When hematocrit levels are lower than that percentage, the MAP decreases in response, which may be due, in part, to the increase in viscosity and the decrease in plasma layer width. [21] Furthermore, affected individuals may have other associated conditions alongside high blood pressure, including formation of blood clots.