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Hyperviscosity syndrome is a group of symptoms triggered by an increase in the viscosity of the blood.Symptoms of high blood viscosity include spontaneous bleeding from mucous membranes, visual disturbances due to retinopathy, and neurologic symptoms ranging from headache and vertigo to seizures and coma.
The causes of this condition are not well understood, but research suggests that it may be caused by a combination of hemodynamic and neurohumoral factors. [8]Some studies have found that orthostatic hypertension may be caused by increased vascular resistance, possibly due to excess plasma shifts or increased blood viscosity.
A diagram explaining factors affecting arterial pressure. Pathophysiology is a study which explains the function of the body as it relates to diseases and conditions. The pathophysiology of hypertension is an area which attempts to explain mechanistically the causes of hypertension, which is a chronic disease characterized by elevation of blood pressure.
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.
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.
Blood pressure varies over longer time periods (months to years) and this variability predicts adverse outcomes. [18] Blood pressure also changes in response to temperature, noise, emotional stress, consumption of food or liquid, dietary factors, physical activity, changes in posture (such as standing-up), drugs, and disease. [19]
A hypertensive emergency is not based solely on an absolute level of blood pressure, but also on a patient's baseline blood pressure before the hypertensive crisis occurs. Individuals with a history of chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension , including fatigue ...
[18] [19] [20] High blood pressure affects 33% of the population globally. [9] About half of all people with high blood pressure do not know that they have it. [9] In 2019, high blood pressure was believed to have been a factor in 19% of all deaths (10.4 million globally). [9] Video summary