Edema (oedema, unit h.) - excessive accumulation of fluid in tissues and serous cavities of the body, manifested by changes in their volume and other physical properties (turgor, elasticity, etc.), a violation of the function of tissues and organs. O. - an important symptom of various pathological processes, which allows to recognize general and local circulatory disorders, kidney, liver, endocrine system and other causes of water-salt metabolism. The generality of some mechanisms of origin, as well as clinical manifestations, the prognostic value of O. determined the attitude towards them as an independent clinical syndrome requiring special treatment, often along with therapy of the underlying disease.
There are local, or localized, O. associated with a violation of the balance of fluid in a limited area of body tissues or in the body, and general, generalized, O. based on a positive water balance in the body. The latter become clinically pronounced when the volume of interstitial fluid increases by about 15%, which is about 2 liters for a person with a body weight of 70 kg. Massive generalized OA is called anasarka.
Swelling is often accompanied by kidney disease (acuteand chronic glomerulonephritis, nephrotic syndrome) and cardiovascular system with circulatory insufficiency: vein lesions (occlusion of hollow veins): liver diseases (liver cirrhosis, occlusion of hepatic veins); diseases of the endocrine system (hypothyroidism, diabetes mellitus); giponokoticheskie state, for example, in severe oncological processes (cachetic O.). Other causes of OA development are alimentary dystrophy, pregnancy, toxicosis with the use of certain medications (estrogenic oral contraceptives), rapid intravenous injection of a large amount of fluid, etc. There are special forms of O. edema of the lungs, cerebral edema, and laryngeal edema.
The positive water balance of the body is, inmainly due to excessive retention of sodium by the kidneys - the main osmotic cation for intercellular fluid and blood plasma. About 40% of the total amount of sodium is found in the cartilage and bones, 7-8% of sodium is contained in the intracellular fluid, and the rest of its mass is in the extracellular fluid. Approximately 70% of the total amount of sodium is exchanged and is in mobile equilibrium with the sodium of the extracellular fluid (see Water-salt metabolism). With an increase in the concentration of sodium in the extracellular fluid, the total water flow to it increases, thirst develops and, consequently, the need for additional water intake increases, the secretion of the antidiuretic hormone (ADH) increases, causing water retention by the kidneys. The positive balance of sodium in the body is due to both its proportional distribution in the intravascular and interstitial spaces, and the predominant concentration of this cation in the interstitial space due to chronic circulatory insufficiency, the development of nephrotic syndrome, liver cirrhosis, conditions accompanied by protein, hormonal and idiopathic deficiency. This hyperosmia of the extracellular sector causes an increase in the secretion of vasopressin, which enhances the sorption of water in the renal tubules and lead to excessive delays in its body. However, the main reason for the accumulation of sodium in edematous syndrome is hypersecretion of aldosterone, caused by hypovolemia or a decrease in cardiac output. Reduction of renal blood flow increases the production of renin by the kidneys and the formation of angiotensin II, which, in turn, stimulates the secretion of aldosterone. As a result, sodium reabsorption in the distal nephron increases, the osmotic pressure of the extracellular fluid increases; The secretion of vasopressin increases again and water is excessively reabsorbed. In itself, an excess of aldosterone is not capable of causing a steady sodium retention (the kidneys "escape" from its action). Reduced sodium filtration with reduced renal blood flow is often combined with increased reabsorption in the proximal areas of the nephron, which depends little on aldosterone.
Although the renin-angiotensin-aldosterone systemplays an important role in maintaining the sodium balance and the volume of extracellular fluid, its functioning can not be considered separately from other regulatory mechanisms associated with the action of natriuretic hormone, changes in directing forces and (or) permeability of the proximal tubule, redistribution of renal blood flow, direct exposure to catecholamines for reabsorption of salts and fluid, the effect of prostaglandins and kinins on renal hemodynamics and, possibly, tubular transport.
Intensity of water exchange in tissues (its volumefiltration, reabsorption, outflow with lymph) depends on the amount of blood flow, the area of the filtering and reabsorbing surfaces and on the permeability of the capillary walls (see Biological Membranes). Changes in these parameters are regulated by neuroendocrine mechanisms with the help of local biologically active substances. The main factors leading to the disruption of the local water balance are the increase in hydrostatic pressure in the capillaries; decrease in oncotic pressure of blood plasma; increase in the oncotic pressure of the interstitial fluid; reduction of tissue mechanical pressure; increased capillary permeability; violation of outflow of lymph. Depending on which of the listed factors are leading in the pathogenesis of O. they are divided into mechanical (stagnant), hypo-oncotic, membranogenic, lymphostatic (see Lymphostasis), etc.
Clinical O. when heart failure is characterized by symmetry, a gradual increase in the underlying points of the trunk (in the horizontal position of the patient), on the lower limbs. The skin to the touch is often cold, often cyanotic. Among the clinical symptoms of heart failure, dyspnoea, stagnant wheezing in the posterior sections of the lungs, cavitary O. especially hydrothorax (more often right-sided), hepatomegaly.
Nephrotic edema. Nephrotic syndrome) are localized on the face (manifested mainly in the morning hours), on the anterior abdominal wall, limbs, quite quickly shifted when the position of the body changes. The puffy skin is dryish, soft, pale, sometimes shiny. Often there is ascites, less often hydrothorax. Dyspnea, as a rule, is not observed. Characteristic proteinuria, hypoproteinemia and other manifestations of renal pathology are characteristic.
Nephrite O. develops rapidly in the earliest stages of acute glomerulonephritis (see Nephritis). The oedematous skin is pale, dense, with normal temperature. O. localized primarily on the face, as well as on the upper and lower limbs. Sometimes there are hydrothorax, hydropericardium. Characterized by hypertension, hematuria and proteinuria, hypoproteinemia. Renal blood flow and glomerular filtration are reduced.
Edema with cirrhosis of the liver. as a rule, occur in the late stages of the disease with severe portal hypertension. Are ascites, swelling on the legs, rarely hydrothorax. The oedematous skin is rather dense, warm. There are signs of the underlying disease, as well as anemia, hypoalbuminemia, hyponatremia, hypokalemia. The secretion of aldosterone and vasopressin is increased.
Cachectic O. occur with alimentary dystrophy. various diseases, accompanied by a lack of assimilation of protein or its great loss. The forms of O. are different both in size and in localization (limbs, trunk, face). The oedematous skin is of a dough consistency, dry. There are signs of severe neuromuscular depletion, hypoproteinemia, hypoalbuminemia, hypoglycemia, hypocholesterolemia. Kidney blood flow and glomerular filtration does not change significantly, tubular reabsorption is increased.
Edema in pregnant women can be due toheart failure, exacerbation of chronic glomerulonephritis, late toxicosis of pregnant women (see Toxicosis of pregnant women). Dropsy of pregnant women is usually found after the 30th, rarely after the 25th week of pregnancy. The puffy skin is soft, damp. O. appear first on the legs, then on the external genitalia, anterior abdominal wall, back, lumbar region. A moderate hypoproteinemia and hypoalbuminemia, an increase in the secretion of aldosterone are revealed.
The latent fluid retention is determined byregular measurement of body weight, control of diuresis, and also with the help of the McClure-Aldrich test. It consists in the introduction of 0.2 ml of a 0.85% solution of sodium chloride intradermally on the inner surface of the upper half of the forearm until the formation of a "lemon crust". The time required for complete resolution of the injected solution is taken as the sample index, which in adults is 60-80 min. Acceleration of resorption indicates a water retention in the body, a slowing down of resorption - for dehydration. Lymphatic O. is recognized by the increase in the volume of the limb or part of the body, swelling of the skin and subcutaneous tissue, reducing their elasticity. When pressing, a dough-like consistency is revealed, and after the finger is removed from the skin surface, a fossa is formed. Often, puffy skin is pale or cyanotic on the lower limbs, often covered with cracks, from which fluid flows: trophic disorders are detected, hyperpigmentation of the skin.
Oval cavities are recognized with the help of physical and instrumental methods of examination. The character of O. is clarified on the basis of their characteristics, the analysis of the clinical manifestations of the underlying disease.
Treatment generalized O. complex, includes treatment of the disease that caused the development of edema; activities aimed at increasing the excretion of sodium and water and reducing their consumption. The appointment of bed rest is necessary for massive OA of any origin. It is suggested that this will improve the response to diuretics by increasing renal perfusion. Bandaging of legs or other edematous areas with an elastic bandage can significantly reduce O. This method causes an increase in diuresis and sodium naresis. Ultrafiltration can also be effective for some patients with massive OA and resistance to diuretics or in cases where rapid fluid removal is required. In connection with the emergence of effective diuretics to mechanical removal of edematous fluid is rarely resorted, but this method is not excluded from medical practice. Often after the paracentesis, the effect of diuretics is increased. Limiting the intake of sodium and water with food is an important component of edema treatment. With more generalized O. or a combination of local O. with significant swelling of the tissue, additional measures are required to increase the excretion of both salt and water in the urine, using either diuretics alone or a combination of them with other methods (for example, administration restrictions in the diet). Assign a diet with a restriction of consumption of table salt to 1-1.5 grams per day (with diuretics 3-4 grams per day), liquids up to 1-1,2 l, sometimes up to 600-800 ml. More significant, but short-term limitations are advisable in OA caused by glomerulonephritis. A diet with a sharp restriction on the amount of sodium is poorly tolerated by most patients, and prolonged use of it can aggravate the disturbance of water-electrolyte metabolism, cause chlorpenic azotemia, and salt depletion syndrome. Excessive restriction of fluid intake in the presence of O. can lead to the emergence of symptoms of hypernatremia. When giponokoticheskih O. designate a protein-rich food (excluding cases of kidney and liver failure). To reduce the capillary permeability used vitamins B1. C and P.
Treatment with diuretics alone has a numberdisadvantages: there is a large loss of salt and water from the vascular bed than from the interstitial space, the increased volume of which is actually the edema. With a negative balance of fluid, the volume of blood plasma drops sharply, which in a number of cases, especially in combination with hyponion, can lead to the development of collapse. With heart failure, a decrease in the volume of circulating blood leads to a decrease in venous return to the heart, which is even more responsible for a small cardiac output. In addition, each diuretic has, as a rule, a side effect.
The most widely used sulfonylamidediuretics, which are divided into two subgroups: thiazide and non-azide. Most of them are capable of inhibiting carbonhydrase and acting on the proximal renal tubule. In the initial part of the nephron they inhibit the active transport of sodium.
Diuretics acting in the area of the nephron loop(furosemide, ethacrynic acid, bumetanide and triflocin) are most effective - they are able to increase urinary sodium excretion up to 20-30% of the filtered amount. The main mechanism of their action is the inhibition of active transport of sodium and chlorine ions. "Loop" diuretics have a powerful diuretic effect and a small side effect.
Potassium-sparing diuretics (veroshpiron,triamterene) differ in structure, but they act on the same nephron site-the distal tubule; have a weak effect (an increase in excretion of 2-3% of the filtered amount). Side effects are few. They are used more often in combination with other diuretics.
Osmotic diuretics, organic mercury diuretics have limited application.
To prevent and partially treat O. in venous insufficiency, flavonoids, horse chestnut extracts (escusan), rutin, venauruton, esflazid, gliwenol, etc. are used.
Despite these features of diureticsare very effective and extremely useful medicines. Treatment should be controlled by measuring diuresis and body weight of patients, as well as by studying the dynamics of Na + and K + blood ions.
Pediatric syndrome in children . The origin of OA in children and adults largely coincides, but there are features of the etiology and pathogenesis of OA in children of different age groups.
Swelling in newborns can develop soonafter birth. They are more often observed in premature infants and are caused by transient hypoproteinemia, imperfect water-salt metabolism, reduced renal concentration function and high permeability of the capillary walls. O. begin with distal parts of the extremities, sometimes the genital organs; appear on the 3-4th day after birth and disappear within a week.
Hemolytic disease of the newborn is sometimes manifested by generalized general edema at the time of the birth of the child (see Hemolytic disease of the fetus and newborn).
Skelredema (newborn) manifests itself in the firsta few days of life and is significantly different from other O. dense swelling of the skin, often on the lower limbs, but without a tendency to generalization. It is observed in premature babies with low body weight, disappears after several weeks with full nutrition and good general care. Sclera (newborns) are more severe, which in some cases can be generalized. The cause of O. in neonates may be a congenital nephrotic syndrome.
Edema in infants is often due tohereditary hydrolysis, when there is a rapid loss of fluid in the restriction of salt and carbohydrates and the same rapid delay in connection with changes in diet. This condition is within certain limits considered as possible for all children up to 3 months of life. With chronic disorders of nutrition and digestion (syndrome of impaired intestinal absorption, dystrophy), O. develop slowly, starting with the hands and feet. At the heart of these O. lie an increased loss of albumins through the intestine along with the mucus and insufficiency of their intake with food. O. disappear after the administration of a sufficient amount of protein-rich food. Insufficiency of vitamins C and group B also leads to hydrolylability with propensity to edema.
Already in the first months of life the cause of O. may be hypothyroidism (amyreosis) with a clinical picture of myxedema. Congenital disorders of the lymphatic drainage (lymphedema) are manifested by O. distal parts of the legs. O. have a soft consistency without distinct boundaries, the skin is pale.
For children of preschool age, increasedhydrolysis is not characteristic due to better regulation of water-salt balance by kidneys and liver. Therefore, O. develop mainly in the same diseases as in adults. Special causes of OA development in children of this age can be celiac disease (see Gluten disease) and cystic fibrosis. The main pathogenetic mechanism of O. is hypoproteinemia.
In children of school age, the formation of O. often associated with acute diffuse glomerulonephritis, which can also occur with nephrotic syndrome; as the cause of O. acquires the importance of amyloidosis of the kidneys, as well as diseases that cause the onset of OA in adults - heart failure in decompensated heart diseases, portal hypertension with cirrhosis, phlebothrombosis, etc.
With age, the frequency of OA allergic origin, in particular angioedema of Quincke, increases, which develops sharply, more often on the face, is of a regional character.
When insect bites develop local O. with reddening of the skin, itching, burning. Focal inflammatory processes are also accompanied by local edema.
Treatment of O. in children is conducted on the same principles as in adults. The effectiveness of dehydration therapy is controlled mainly by measuring in the dynamics of body weight (the measurement of diuresis in children is often difficult and less reliable reflects the water balance), as well as the restoration of the functions of edematous organs and tissues.
Bibliogr. Homeostasis, ed. L.D. Horizontova, M. 1976; Zernov N.G. and Tarasov OF Semiotics, 1984; Kidney and homeostasis in red. S. Clara, per. with English. M. 1987.