Burn disease

Pathological physiology and pathogenesis. The problem of the pathogenesis of burns, despite numerous studies that is not allowed. Burn pathology is not limited to local changes in tissues; extensive (more than 10% of body surface) and deep O. causes versatile functional disorders of internal organs and systems of the entire organism, that justifies the term "burn disease". The total area of skin necrosis is the main factor determining the nature of the flow of burn disease.
In the deep and widespread thermal lesions, to talk about a periodization of burn disease. Most authors allocates the period of burn shock, acute toxemia, septicotoxemia and convalescence. This periodization largely notional. The shock is not always expressed, toxaemia occurs in the first days after O. and inevitable during all periods of illness; burn infection marked in the first day.
The period of burn shock in his torpid phase differs significantly from current of shock different origins [traumatic turnstile (shock from strong dragging limbs), anaphylactic]. Specific relative stability in blood pressure. Animals fatal burn the degree of blood pressure does not exceed 20-30% of the original; naturally reduced pulse pressure minimum pressure increases in the absence of changes in maximum or remains unchanged in the fall of max. Volumetric and linear blood flow is usually reduced in 1,5-2 times; using the technique of resistography been shown to increase the resistance and, accordingly, the tone of blood vessels in burnt animals. The decrease in the blood flow and value of arterial vascular tone does not depend on fluctuations of blood pressure. All GRT indicates the absence of vasomotor failure in the initial period of burn disease.
The large role in development of pathology of the initial period of burn disease belongs to a weakening of the heart activity. In experiments on dogs it is shown that already in the first hours after burn cardiac output is reduced by 50%, and is not dependent on the volume of circulating blood.
The fall in the volume of circulating blood - plasma loss is permanent and a characteristic manifestation of burn shock. This symptom is caused by the increase in the permeability of capillaries, not only in the area of the burn, but also everywhere. Leak plasma proteins in body fluids and subsequent fall of the colloid-osmotic pressure of blood; increased vypocetni of fluid in the tissue contributes to the increase of hydrostatic pressure in the capillaries.
Many authors give plasmopara crucial importance in the mechanism of development of burn shock. Recently accumulated facts that contradict this view. It was shown that thermal shock in rabbits develops without hemoconcentration. According to N. A. Fedorov, dogs lethal O. flame is observed only short-decrease volume of circulating blood, while not reaching such a large extent, to explain the severity of pathology initial period of burn disease. Often restore the circulating blood volume coincides with the deterioration of animals.
Cardinal symptom of burn disease is a disorder of the kidneys. In severe burns always see oliguria or anuria arising under the influence extrarenally and renal factors. Has been severe disorder of renal hemodynamics, reflected in a sharp decrease in glomerular filtration rate and effective renal blood flow. Poor circulation in the kidney due to spasm of arterioles of the glomeruli, and in a greater degree - discharge, therefore develop persistent ischemia tubular Department of nephron and congestive hyperemia of glomeruli with symptoms of increased glomerular permeability of membranes. Especially indicative for severe burn injury is a significant defeat of secretory function of kidneys.
Already in the first hours after the burn is developing a profound defeat of the liver with the violation of protein, protrombinovogo and excretory functions. When Acting moderate severity the first two functions are restored on the 4 - 5th day, while excretory - only 30 - 35-th day.
Burn disease is accompanied by a profound violations of all types of metabolism. Already in the stage of burn shock marked the phase changes of breath; in erectile - increased consumption of oxygen and gas exchange; in subsequent intensity of these processes is falling. Noted the discrepancy between the high breathing ability burnt tissues of the body and reduced gross consumption of oxygen, which should be explained by the violation of the blood and tissues. Infringement of oxidative processes lead to accumulation of non-completely oxidized products of metabolism. Immediately after burn increases the amount of organic acids in the blood (300% and above), increases the rate of nedookislennye in the urine.
Already on 1-2 day after burn begins generalized breakdown of proteins in tissues and organs, are defined by a number of indicators: hypoproteinemia, negative nitrogen balance, increased excretion of creatine, ammonia, amino acids: the residual nitrogen in the blood is increased. In patients with O. moderate increased protein breakdown lasts until 30 days after O. they have lost almost 25% of the weight. Identified four periods in the pathology of protein metabolism: 1) acute catabolic. 2) late catabolic, 3) anabolic, 4) late recovery period. The duration of each period of 10 days. To maintain metabolic balance is necessary in the first period 20-27 g, in the second - 13 to 16 grams in a third - 3.3 - 9.3 g and in the fourth - 3.7 g nitrogen per day per 1 m2 body surface.
One of the reasons of high burn proteolysis is activation of proteolytic enzymes in the damaged skin with a connection and their accumulation in the blood. Generalized breakdown of proteins leads to the accumulation of toxic active ingredients, some of which has a high physiological activity (histamine, bradykinin). Their importance in the pathogenesis of the initial period of burn disease does not cause doubts.
If you burn shock permanently observed violations of the ion balance. The content of sodium in the blood naturally decreases because of its transition into the tissues, the number of potassium increased considerably and highlight it with urine detained.
Between the so-called burns shock and subsequent stages of burn disease cannot install border. Most of the symptoms can be observed in stages toxemia and bacteremia.
The main mechanism of burn shock most authors explain, the perspective neurogenic theory. Powerful pain impulses to burn on afferent paths reaches of the basal ganglia and the cerebral cortex, causing first excitement, then in the subsequent depletion and beyond external braking. The pathogenic significance nociceptive stimuli is recognized by most researchers. This view is supported by the favorable results of the use of local anesthetic funds.
Beyond braking in torpid phase of shock is protective for the Central nervous system, leading to reduced demands that a profitable in conditions of burn hypoxia. On the other hand, we must bear in mind and pathological side of this phenomenon, as braking centers of the brain reduces the intensity of the most important regulation of vegetative functions burnt body.
Admittedly, neurogenic mechanisms in the pathogenesis of burn disease is studied very little. Remain unclear localization and character of functional changes in the Central and peripheral nervous system and caused these changes disorders of organs and systems. In response to the pain involved, the system hypothalamus - pituitary - adrenal axis, which should be regarded as an expression of the General adaptation syndrome.
In severe burns should take into account other pathogenetic mechanisms of plasma loss with violation of ionic balance and decrease volume of circulating blood and toxemia. Toksemicheskim theory was put forward from the beginning of the emergence of the doctrine of the pathogenesis of burn disease. In addition to blood specimens and exudate burn hearth also have toxic properties. The numerous data testify that the starting point of burn toxemia is a hotbed of thermal damage. Theory toxemia has many opponents, who deny the existence of toksemicheskim factor in burnt, especially in the early period of the disease. It should be recognized that in the literature there is great controversy about the nature, place, time of formation and the mechanism of action of the so-called burn toxin. However, to deny the very fact of autointoxication with severe burns impossible.

Research in the field of infectious immunology burn disease introduced new arguments in favor toksemicheskim theory: N. A. S. Fedorov and Century. Skurkovich has established the fact of appearance in the burnt skin of animals and humans of autoantigen that is not healthy. Burn antigen deprived of species specificity, but has specificity nosological, i.e. not detected in tissues with a different pattern of damage (turpentine inflammation, aseptic injury). Burn antigen is found in the blood within 10-15 days after burn. Many authors have proved the emergence of specific burn autoantibodies in the blood of animals and humans in different terms after O. it is also Shown that the convalescent serum 20-30 days after O. acquires antitoxic effect in relation to the toxic serum taken 24 hours after the burn; burn antivenoms held in the blood for many months. For the detection of toxic and antitoxic properties serum burnt were proposed methods of biotesting with the use of tissue culture (leukocyte film, cancer cells). Antitoxic properties serum are associated with b - and V-globulins and found in the same timeframe as complementative autoantibodies. These studies served as a theoretical justification for the imposition of the so-called immunotherapy in animals and people with fresh burns to overcome toxemia.
Numerous studies have shown that the effect of the serum of burn reconvalescent with high titers of burn antibody-antivenoms in animals and people with severe O. has a distinct therapeutic effect: stops vomiting, decrease leukocytosis and hemoconcentration, increased blood volume, quickly returning to normal function of the kidneys and liver, reduces the intensity of intensive protein distraction, increases the phagocytic activity of leucocytes, prevents the development of anemia, accelerates the formation of granulation in place thermal damage, normal mineral metabolism in calcified tissues. Established therapeutic effect serum of burn reconvalescent in thermal burns of eyes, during O., combined with radiation sickness.
Immunotherapy should be applied as early as possible, and to successfully overcome toxemia required frequent the serum or blood in large doses (10-15 ml/kg of body weight); it should serological or biological testing used for transfusion funds.
In experimental conditions also impressive was izoimmunnaya burns serum. To get her healthy dogs were exposed to immunization by multiple intravenous infusions of blood dogs with severe Acting Through 7-8 days after the last immunization of animals took the blood, from which he received healing serum. Transfusion of a serum dogs lethal Acting has also a distinct therapeutic effect, phenomenon of autointoxication avoided.
Apparently, in the first days after burn in the body accumulate toxic substances with antigenic properties (burn autoantigen); thus, noncommunicable immunotherapy is a treatment method for overcoming burn toxemia.