44. Gangrene: types, causes, pathological characteristics, significance for the body.

Gangrene (from the Greek gangrania — fire) is the necrosis of tissues in contact with the external environment. The tissues have a black color as a result of the formation of iron sulfide from hemoglobin iron and hydrogen sulfide in the air. Gangrene can develop in various parts of the body, lungs, intestines, uterus. There are varieties of gangrene — dry, wet, gas and pressure sores.

With dry gangrene, tissues are mummified, and the zone of demarcation inflammation is clearly defined at the border with preserved living tissue. It occurs in the extremities and on the body with atherosclerosis, frostbite and burns, Raynaud's disease and vibration disease, with severe infections.

Pathomorphology: Tissues acquire a brownish-gray, gray-green or black color, like burnt tissues, (due to the breakdown of hemoglobin in the form of sulfmethemoglobin, blood pigments and their transformation into iron sulfide). Gangrenous tissue areas have no defined boundaries.

Wet gangrene occurs in tissues under the action of putrefactive microorganisms. The tissue swells, becomes edematous, emits a fetid odor, the demarcation zone is not defined. Wet gangrene occurs in the lungs, intestines and uterus. In children weakened by measles, wet gangrene can develop on the skin of the cheeks, perineum and is called a noma (Greek. sweat is a water cancer).

Bedsore is a type of gangrene of trophoneurotic origin. It occurs in places of greatest pressure in weakened patients suffering from cardiovascular, infectious, oncological and nervous diseases. Bedsores are usually localized in areas of the body that are exposed to the greatest pressure in bedridden patients.

Gas (anaerobic) gangrene occurs in injuries and other wounds with massive destruction of muscles and even bone crushing under the influence of certain anaerobic microorgs (Vas. perfrmgens, etc.), an image in the process of vital gases. At the same time, the swollen dead tissue does not have clearly defined boundaries. Due to the spread of blood circulation and the breakdown of erythrocytes in the dead tissue, a large number of sulfmethemoglobin, blood pigments and iron sulfide are formed, the dead mass is dark brown/ almost black.

Causes of gangrene:

1. trauma (burn, frostbite)

2. Infections

c) vascular disorders (atherosclerosis, arterial thrombosis, venous congestion, lymphostasis).

The significance and outcome of gangrene depend on the cause, the specific strata and functions of the cl-k and tc-y, the reactive composition of the organ and the influence of the environment. environment, but always an irreversible pathological process. Under the influence of necrosis, decay products of dead cells and tissues, a reactive, so-called demarcation inflammation occurs with vascular hyperemia, the release of serous exudate, leukocytes, lymphocytes and macrophages from them.

45. Violations of the content of tissue fluid: definition, types, pathogenetic factors. Types of edema depending on the cause of the disease. Clinical significance.

The tissue fluid is poor in proteins (1-2% at most) and is associated in cells with protein colloids, and in connective tissue with proteins and glycosaminoglycans of the basic substance. Its main mass is in the intercellular substance. Violations of the content of tissue fluid are expressed either in its increase or decrease.

Edema can develop in all tissues, but it is most easily noticeable in the subcutaneous tissue. The earliest clinical evidence of edema in it is pasty — the presence of an indentation (dimple) (when pressing with a finger, a dimple remains, which does not disappear after stopping pressing). Visible swelling of the skin occurs only when a large amount of excess fluid has collected. In the early stages, the so-called hidden edema is detected by weighing patients.

The concept of edema also includes the accumulation of fluid in the cavities (hydrothorax, pneumothorax, ascites)

Edema can be classified as:

1. limited (caused by a local violation of the mechanism of fluid metabolism in the tissue);

2. general or generalized (caused by the retention of sodium and water ions in the body).

In the clinic, fluid distribution disorders in generalized edema are caused by gravity (gravity), that is, fluid accumulates mainly around the ankles in outpatient (“walking”) patients and in the sacral region in “bedridden" patients

Types of edema:

• Allergic Acute allergic reactions cause a local release of vasoactive substances, such as histamine, which dilate the lumen of the vessels of the microcirculatory bed and cause an increase in capillary permeability. Allergic edema is most often localized in the skin, where it manifests itself in the form of blisters (urticaria). Less often, large areas of the skin may be affected, the larynx and bronchioles may be involved, causing narrowing of the respiratory tract (angioedema).

• Edema due to venous congestion: the severity of venous congestion depends on the intensity of collateral venous circulation in this area. In cases where venous stagnation is accompanied by complete failure of the drainage function of the veins, severe edema and hemorrhages develop, since hydrostatic pressure is increased, accompanied by rupture of capillaries

• Edema due to lymphatic stagnation: when lymphatic drainage is disrupted, a small amount of protein that exits the capillaries by pinocytosis and as a result of ultrafiltration is not removed and accumulates in the interstitial space.

• General edema occurs as a result of an increase in the total number of sodium and water ions in the body when they are delayed by the kidneys, when the level of glomerular filtration is reduced or the secretion of aldosterone is increased.

• Cardiac edema: Heart failure is accompanied by a decrease in left ventricular blood output. Reducing the release of blood into the large circulatory system leads to a decrease in filtration pressure in the glomeruli, stimulation of the juxtaglomerular apparatus and renin secretion. Renin, in turn, stimulates increased production of aldosterone

• Renal edema: in acute glomerulonephritis, the level of glomerular filtration is noticeably reduced, which leads to a delay in sodium and water ions and the development of moderate edema. Unlike other types of general edema, in acute glomerulonephritis, edema usually first appears in the tissues surrounding the eyes, on the eyelids, and then they spread to the hands and feet.