Study of subcutaneous fat

The subcutaneous fat layer is examined almost simultaneously with the skin. The degree of development of fatty tissue is more often in accordance with the body weight and is determined by the size of the skin fold on the abdomen in the navel region; with a sharp decrease in the skin is easier to take in the fold, with a significant deposition of fat, this is often not possible to do.

It is of great clinical importance to detect edema.

Edema

Swelling (fluid retention) occurs primarily in the subcutaneous tissue due to its porous structure, especially where the fiber is more friable. Hydrostatic and hydrodynamic factors explain the occurrence of edema in the low-lying areas of the body (lower extremities). The latter factor plays an important role in the development of edema in heart diseases accompanied by congestive heart failure. Edema appears more often by the end of the day, with prolonged stay of the patient in an upright position. At the same time, with kidney disease, small swelling more often appears primarily on the face (in the eyelid) and usually in the morning. In connection with this, the patient may be asked whether he feels heaviness and swelling of the eyelids in the morning. The relatives of the patient can pay attention to the appearance of such puffiness for the first time.

In diseases of the heart, kidneys, liver, intestines, endocrine glands, swelling can be widespread. When there is a violation of venous and lymphatic drainage, allergic reactions are often asymmetric edema. In rare cases, in elderly people, they can appear with prolonged stay in an upright position, which (like swelling in women during the hot season) is not of great clinical significance.

Patients can consult a doctor with complaints of swelling of the joints, swelling of the face, legs, rapid increase in body weight, dyspnea. With a general delay in the fluid, swelling occurs primarily, as already mentioned, in the low-lying parts of the body: in the lumbosacral region, which is especially noticeable in persons occupying a vertical or semi-recumbent position. This situation is typical for congestive heart failure. If the patient can lie in bed, swelling occurs primarily on the face, hands, as happens in young people with kidney disease. Fluid retention is caused by an increase in venous pressure in some area, for example, with pulmonary edema due to left ventricular failure in cases of ascites in patients with increased pressure in the portal vein system ( portal hypertension ).

Usually the development of edema is accompanied by an increase in body weight, but the initial edema on the legs and lower back is easily detected by palpation. It is most convenient to press the tissue against the dense surface of the tibia with two or three fingers, and in 2-3 s in the presence of edema, pits are found in the subcutaneous adipose tissue. A weak degree of puffiness is sometimes referred to as "pasty". Pits on the lower leg are formed with pressure only if the body weight has increased by no less than 10-15%. With chronic lymphoid edema, myxedema (hypothyroidism) edema is more dense, and when pressed, the fossa is not formed.

As with general and local edemas, the important factors in their development are the factors involved in the formation of the interstitial fluid at the level of the capillaries. Interstitial fluid is formed as a result of its filtration through the capillary wall - a kind of semipermeable membrane. Some of it returns back to the vascular bed thanks to the drainage of the interstitial space through the lymphatic vessels. In addition to the hydrostatic pressure inside the vessels, the rate of fluid filtration is influenced by the osmotic pressure of proteins in the interstitial fluid, which is important in the formation of inflammatory, allergic and lymphatic edema. The hydrostatic pressure in the capillaries varies in different parts of the body. Thus, the average pressure in the pulmonary capillaries is about 10 mm Hg. While in the renal capillaries about 75 mm Hg. Art. With the vertical position of the body as a result of gravity, the pressure in the capillaries of the legs is higher than in the capillaries of the head, which creates the conditions for the appearance of slight edema of the legs by the end of the day in some people. The pressure in the capillaries of legs in a person of medium height in the standing position reaches 110 mm Hg. Art.

Expressed common swelling (anasarka) can occur with hypoproteinemia, in which the oncotic pressure, mainly associated with albumin plasma, falls and the fluid lingers in the interstitial tissue, not entering the vascular bed (often with a decrease in the amount of circulating blood - oligemia, or hypovolemia).

The causes of hypoproteinemia can be a variety of conditions, combined clinically by the development of edematous syndrome. These include the following:

1. insufficient intake of protein (starvation, poor-quality nutrition);
2. impaired digestion (impaired secretion of enzymes by the pancreas, for example, in chronic pancreatitis, other digestive enzymes);
3. violation of absorption of food products, especially proteins (resection of a large part of the small intestine, damage to the wall of the small intestine, gluten enteropathy, etc.);
4. violation of albumin synthesis (liver disease);
5. significant loss of proteins in the urine with nephrotic syndrome;
6. loss of protein through the intestine (exudative enteropathy ).

Reduction of intravascular volume of blood, associated with gigoproteinemia, can cause secondary hyperaldosteronism through the renin-angiotensin system, which contributes to sodium retention and edema formation.

Heart failure causes edema due to the following reasons:

1. violation of venous pressure, which can be detected by the expansion of veins on the neck;
2. the effect of hyperaldosteronism;
3. violation of renal blood flow;
4. increased secretion of antidiuretic hormone;
5. a decrease in oncotic pressure due to stagnation of blood in the liver, a decrease in albumin synthesis, a decrease in protein intake due to anorexia, a loss of protein in the urine.

Renal edema is most pronounced in nephrotic syndrome, when a significant amount of protein (primarily albumin) is lost due to pronounced proteinuria, which leads to hypoproteinemia and hypo-oncotic fluid retention. The latter is exacerbated by developing hyperaldosteronism with an increase in sodium kidney reabsorption. The mechanism of the development of edema in an acute syndrome (for example, at the height of a typical acute glomerulonephritis ) is more complicated , when the vascular factor (increasing the permeability of the vascular wall) seems to play a more significant role, in addition, sodium retention, which leads to an increase in the volume of circulating blood, "swelling of the blood" (hypervolemia, or plethora). As with heart failure, swelling is accompanied by a decrease in diuresis (oliguria) and an increase in the body weight of the patient.

Local edema can be caused by the causes associated with venous, lymphatic or allergic factors, as well as local inflammatory process. With vein compression from the outside, vein thrombosis, venous insufficiency, varicose enlargement, capillary pressure in the corresponding area increases, which leads to blood stasis and the appearance of edema. Most often, vein thrombosis develops in diseases requiring prolonged bed rest, including postoperative conditions, and also during pregnancy.

When lymphatic drainage is delayed, water and electrolytes are reabsorbed back into the capillaries from the interstitial tissue, but the proteins that are filtered from the capillary to the interstitial fluid remain in the interstitium, which is accompanied by a water retention. Lymphatic edema also occurs as a result of lymphatic obstruction by filarias ( filariasis - a tropical disease). In this case, both legs, external genital organs can be affected. The skin in the affected area becomes rough, thickened, elephantiasis develops.

In the local inflammatory process, as a result of tissue damage (infection, ischemia, exposure to certain chemicals such as uric acid), histamine, bradykinin and other factors that lead to vasodilation and increased capillary permeability are released. Inflammatory exudate contains a large amount of protein, as a result of disrupted the mechanism of movement of tissue fluid. Often, at the same time, there are classic signs of inflammation, such as redness, pain, local temperature increase.

An increase in the permeability of capillaries is also observed in allergic conditions, but unlike inflammation there is no pain and there is no redness. When swelling Quincke - a special form of allergic edema (more often on the face and lips) - the symptoms usually develop so quickly that a threat of life is created due to edema of the tongue, larynx, neck (asphyxia).

[1], [2], [3], [4]

Disturbance of subcutaneous fat development

In the study of subcutaneous fat, usually attention is paid to its increased development. With obesity, excess fat is deposited in the subcutaneous tissue fairly evenly, but more so in the abdomen. There may also be an uneven deposition of excess fat. The most typical example is Cushing's syndrome (observed with excessive secretion of corticosteroid hormones by the adrenal cortex), often a cushingoid syndrome associated with prolonged treatment with corticosteroid hormones. Excess fat in these cases is deposited mainly on the neck, face, as well as the upper body, the face usually looks round, and the neck is full (the so-called moonlike face).

The skin of the abdomen is often considerably stretched, which is manifested by the formation of areas of atrophy and scars of purplish-cyanotic color, in contrast to whitish areas of skin atrophy from stretching after pregnancy or large edema.

Progressive lipodystrophy and a significant loss of the subcutaneous fat layer (as well as the fatty tissue of the mesenteric region) are possible , which is observed in a number of serious diseases, after large surgical interventions, especially on the gastrointestinal tract, with fasting. Local atrophy of subcutaneous fat is observed in patients with diabetes mellitus at places of insulin administration. Often the muscle mass of the body also decreases. The extreme degree of such weight loss is called cachexia.

[5], [6], [7], [8], [9], [10], [11], [12], [13], [14]