Hyperemia


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hyperemia

[‚hī·pə′rē·mē·ə]
(medicine)
An excess of blood within an organ or tissue caused by blood vessel dilation or impaired drainage, especially of the skin.

Hyperemia

 

also plethora, an excess of blood in a tissue or organ. One may distinguish arterial and venous hyperemia. Arterial (active) hyperemia arises as a result of increased blood flow in the arteries owing to increased tonus of the vasodilator nerves or decreased tonus of the vasoconstrictor nerves. Among its causes are increased sensitivity of the blood vessels to physiological stimuli or the influence of extraordinary stimuli (such as bacterial toxins, high temperature, and products of tissue decomposition); in humans psychogenic factors (such as shame and anger) play a large role. Arterial hyperemia is characterized by dilatation of the arteries in the hyperemized area, elevation of temperature in the area, acceleration of blood flow, and reddening (for example, hyperemia of the face). It is accompanied by intensification of metabolic processes in the tissues and promotes the regeneration of tissues. Hemorrhages may occur during arterial hyperemia if there are pathological changes in the blood vessels. Arterial hyperemia is induced for therapeutic purposes by means of mustard plasters and cupping glasses. Venous (passive, static) hyperemia occurs when the outflow of blood along the veins is obstructed as a result of pressure on the venous wall (cicatrix, tumor, varicose dilatation of the veins, or edema), while the inflow remains unchanged or when there is a weakening of cardiac activity. Venous hyperemia is characterized by deceleration of blood flow to the point of complete stasis. Oxygen deficit develops in the tissues, the vascular walls become more permeable, and edema develops. Prolonged blood stasis and edema may lead to atrophy of the parenchyma of an organ.

V. A. FROLOV

References in periodicals archive ?
Post-occlusive reactive hyperemia (PORH), an index of microvascular function was calculated as (peak cutaneous blood flow--baseline cutaneous blood flow)/baseline cutaneous blood flow x 100 (12).
In our study, we observed the following light microscopic criteria: Disintegration and discontinuity in villous epithelium, irregularity, enlargement, compression, and edema in villi, decrease in the number of crypts, hyperemia and edema in sub-mucosae, mononuclear cellular infiltration, and PAS (+) reactive cellular counts.
Of those women, 27% (55) experienced problems that included ocular hyperemia, pain, and itchy swollen eyelids.
Conjunctival findings like hyperemia, petechial hemorrhages and papillary or follicular reaction is seen.
Application of color Doppler shows diffuse hyperemia (Figure 11) compared to the contralateral epididymis; spectral Doppler interrogation will demonstrate a high-flow, low-resistance pattern often resulting in a resistive index below 0.
Focal hyperemia and vascular atherosclerosis may also increase permeability of blood brain barrier.
bulbar hyperemia, conjunctival secretions, papillary reaction, trantas spots, corneal involvement at presentation, the severity of disease was graded as per the method described by Bonini et al.
Therefore, FFR equals Pd/Pa, where Pd is the distal coronary pressure across the stenosis, and Pa is the aortic pressure, both measured at maximum coronary hyperemia.
ClickPress, Thu Oct 30 2014] GlobalData's clinical trial report, "Hyperemia Global Clinical Trials Review, H2, 2014" provides data on the Hyperemia clinical trial scenario.
Many times, they will have ocular rosacea with recurrent chalazions, conjunctival hyperemia, or keratitis.
The groups did not differ significantly in the primary endpoint: peripheral vasodilator function expressed as a reactive hyperemia ratio.
Endothelial function is measured by detecting transient increases in blood flow, a marker known as the reactive hyperemia index (RHI).