Edema - a typical pathological process, consisting in excess accumulation of extracellular tissue fluid in the interstitial space.
For etiology, pathogenesis, prevalence, edema is divided into:
Systemic edema occurs as a result of the disturbance of the leading mechanisms of regulation of water-salt metabolism, which is possible with diseases of the heart, kidneys, liver, and gastrointestinal tract.
In accordance with the peculiarities of the etiological factor and mechanisms of development, edema can be:
1) inflammatory, caused by exudation;
2) noninflammatory nature, associated with the intensification of the process of transudation and (or) violation of lymphatic drainage.
Depending on the leading factor determining the development of edema, there are:
1) congestive (mechanical) edema, caused by violation of blood and lymph drainage and increased hydrostatic pressure in microvessels;
2) oncotic, resulting from a decrease in the magnitude of the colloid-osmotic pressure of the blood plasma;
3) membranogenic, appearing with increasing permeability of the capillary wall;
4) swelling associated with active retention in tissues of electrolytes, mainly sodium, and water;
5) lymphogenous, arising from stagnation of lymph.
Depending on the leading cause of development, local edema can be divided into:
At the heart of the pathogenesis of any local edema liesviolation of the Starling equilibrium, which reduces to an increase in intravascular hydrostatic pressure, a decrease in the oncotic gradient, an increase in the permeability of the vascular walls, or a combination of these mechanisms.
The development of edema of a general nature is facilitated by the following factors.
1. Hyperfunction of the renin-angiotensin-aldosterone system and total excess sodium in the body.
2. Lack of formation of the atrial natriuretic factor (PNUF).
3. Reduction in the oncotic pressure of blood plasma due to the loss of oncotically active proteins (loss of proteins in nephrotic syndrome, burn plasmorrhea, with prolonged vomiting, etc.).
4. Increase of hydrostatic pressure in the exchange vessels of the microcirculatory bed.
5. Increased permeability of vascular walls.
6. Enhance the hydrophilicity of tissues.