Burn shock

Burn shock is a pathological process caused by extensive thermal damage to the skin and underlying tissues, leading to severe hemodynamic disorders with a predominant disturbance of microcirculation and metabolic processes in the patient's body. The duration of the period is 2-3 days.

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How does a burn shock develop?

From the moment of receiving a large burn, the circulatory disorders become especially important, which is facilitated by the loss of plasma from the affected surface. Since the first hours, the BCC decreases due to a drop in the volume of circulating red blood cells and plasma, which leads to blood clotting (hemoconcentration). In connection with a sharp increase in the permeability of capillaries (not only in the burn zone, but also in intact tissues) and the release of a significant amount of protein, water and electrolytes from the burned, the volume of circulating plasma significantly decreases. There is hypoproteinemia, mainly due to hypoalbuminemia. Its development is also facilitated by the increased disintegration of proteins in the tissues of the burnt. Reduction in the volume of circulating red blood cells occurs as a result of destruction of red blood cells in the region of burns at the time of thermal trauma and, to a greater extent, as a result of pathological deposition of erythrocytes in the capillary network due to disorders of microcirculation. Reduction of BCC leads to a decrease in the return of blood to the heart, a decrease in cardiac output.

The deterioration of the contractile ability of the myocardium after severe burns is also considered the cause of an early drop in cardiac output. As a result, the amount of blood coming to various organs and tissues decreases, which, combined with a deterioration in the rheological properties of the blood, leads to marked microcirculation disorders. In this case, already in the first hours after receiving the burn, a sharp slowing of the blood flow rate is observed, which is fraught with the switching off of a significant part of the capillaries from the active blood circulation. In small vessels, aggregates of uniform elements appear that prevent the normal passage of erythrocytes through the capillaries. Despite such disorders of hemodynamics, burn shock is accompanied by normal arterial pressure. This is facilitated by an increase in the overall peripheral resistance to blood flow due to vasospasm due to increased activity of the sympathoadrenal system, as well as an increase in blood viscosity due to hemoconcentration and a deterioration in the rheological properties of the blood. Circulatory disorders lead to a sharp disruption of oxygen delivery to tissues and to hypoxia. It is aggravated by its inhibition of respiratory enzymes in the mitochondria, which completely excludes the participation of even delivered oxygen in the oxidative reactions. Under-oxidized metabolic products, especially lactic acid, cause a shift of KOC towards acidosis. Metabolic acidosis promotes further disruption of cardiovascular function.

Burn shock has three degrees: light, heavy and extremely heavy.

Light burn shock develops at the area of deep burns to 20% of the body surface. The victims go to the hospital in a clear consciousness, sometimes there is a brief excitement, they rarely see vomiting, chills. A moderate thirst worries. You can note some pallor of the skin. BP remains within the normal range, a small tachycardia (100-110 per minute) is possible. Violation of the kidneys is uncharacteristic, daily diuresis remains normal, hematuria and azotemia do not. Body temperature in the majority of victims in the first day of normal or subfebrile, and the second - reaches 38 ° C. The hemoconcentration is moderate, the hematocrit does not exceed 55-58%, however, the indicated changes for the second day are stopped. Characteristic increase in the number of blood leukocytes to 15-18h109 / l, a small hypoproteinemia (the level of total protein is reduced to 55 g / l). Bilirubinemia, electrolyte balance disorders and acidosis, as a rule, do not reveal. Moderate hyperglycemia (up to 9 g / l) is observed only in the first day. Usually, most of the victims are taken out of the state of a light burn shock by the end of the first - the beginning of the second day after the lesion. The average duration of the period is 24-36 hours.

Heavy burn shock develops in the presence of deep burns on an area of 20-40% of the body surface. In the first hours after the injury, excitement and motor anxiety are characteristic, and soon there is a retardation with a preserved consciousness. The victim is worried about chills, thirst, pain in the area of burns. Vomiting is observed in a significant number of patients. Skin-free skin and visible mucous membranes are pale, dry, and cold. Often noted acrocyanosis. Characteristic tachycardia to 120 per minute, lowering blood pressure. As a rule, kidney functions suffer, daily diuresis is reduced to 300-400 ml. Observe hematuria, albumin, sometimes hemoglobinuria, increase of residual blood nitrogen to 40-60 mmol / l to the second day. Hemoconcentration is significant (hematocrit 70-80%, Hb 180-200 g / l), the rate of blood clotting decreases to 1 min. Mark leukocytosis to 40x109 / l, accompanied by neutrophilia, often appear young forms up to myelocytes, lympho- and eosinopenia; the number of leukocytes decreases by the end of the third day. The content of the total protein of the blood plasma decreases to 50 g / l in the first and 40 g / l - on the second day. The number of platelets is somewhat reduced. Combined respiratory-metabolic acidosis develops.

An extremely severe burn shock occurs in the presence of deep burns on an area of more than 40% of the body surface. The general condition of the patients, as a rule, is heavy, the consciousness is confused. Short-term excitation is quickly replaced by inhibition and indifference to what is happening. The skin is cold, pale. Characteristic of strong thirst, chills, nausea, repeated vomiting, tachycardia up to 130-150 per minute, weak filling of the pulse. Systolic blood pressure from the first hours can be reduced to 90 mm Hg, and CVP also falls. They note shortness of breath and cyanosis, high hemoconcentration (Hb 200-240 g / l, hematocrit 70-80%). Urinary excretion is sharply reduced, up to anuria, daily diuresis does not exceed 200-300 ml. Urine is dark brown, almost black with the smell of burning. From the first hours after getting a burn, acidosis develops, the paresis of the intestine joins. Body temperature decreased. The duration of this period is 56-72 hours, the lethality reaches 90%.

How is burn shock treated?

Burn shock in children is treated with infusion-transfusion therapy, the volume of which is determined approximately by the Wallace scheme - by the product of a three-fold weight of the child (kg) per% burn. This amount of fluid must be administered to the child within the first 48 hours after the injury. The physiological requirement of the organism in water (from 700 to 2000 ml / day, depending on the age) is satisfied by the additional administration of a 5% glucose solution.

In the first 8-12 hours, 2/3 of the daily amount of liquid is injected, the rest in the next 12 hours. Light burn shock requires the introduction of a daily dose of infusion media, which is about 3000 ml for adults and 1500-2000 ml for children; severe burn shock - 4000-5000 ml and 2500 ml; extremely severe burn shock - 5000-7000 ml and up to 3000 ml, respectively. In elderly and elderly people, it is necessary to reduce the rate of infusion by about 2 times, and reduce the volume to 3000-4000 ml / day. Burned with accompanying diseases of the cardiovascular and respiratory systems should also reduce the volume of transfusions by 1/4 ~ 1/3 of the daily amount.

The above schemes of infusion-transfusion therapy are indicative. In the future, the burn shock is treated under the control of blood pressure, CVP, heart rate, hourly diuresis, hemoglobin level, hematocrit, potassium and sodium concentrations in blood plasma, CBS, etc. The volume and rate of infusion medium administration should be increased at low values of CVP (less than 70 mm of water .st.); high (more than 150 mm of water) indicate a heart failure and the need to stop infusion or reduce the volume of injected media. With adequate therapy, the hourly diuresis is 40-70 ml / h, the concentration of sodium in the blood plasma is 130-145 mmol / l, and the potassium content is 4-5 mmol / l. Hyponatremia is rapidly stopped by the administration of 50-100 ml of 10% sodium chloride solution, and hyperkalemia is usually eliminated. In hypernatremia, 250 ml of a 25% glucose solution with insulin is indicated.

The adequacy of infusion and transfusion therapy is judged on the basis of clinical data: thirst and dry skin indicate a deficiency of water in the body and the development of hypernatremia (should increase oral intake of water, inject glucose solution 5%). Pale and cold skin shows a violation of peripheral circulation [should be administered dextran (reopoliglyukin), gelatin (gelatin), hemodez]. Severe headache, convulsions, weakening of vision, vomiting, salivation are observed in cell hyperhydration and water intoxication (application of osmotic diuretics is indicated). Decrease in subcutaneous veins, hypotension, decrease in skin turgor are characteristic for sodium deficiency (it is necessary to infuse solutions of electrolytes, sodium chloride 10%). With positive dynamics of the patient's condition, restoration of diuresis and normalization of laboratory parameters, the number of injectable infusion media for 2-3 days can be reduced by half.

When conducting infusion-transfusion therapy burned, preference should be given to catheterization of the central veins (subclavian, jugular, femoral), which can be performed through the affected areas of the skin after careful treatment. However, such a catheter should not be used for a long time because of the danger of development of purulent-septic complications.

Sometimes an extremely severe burn shock caused by a combined thermomechanical trauma complicated by bleeding is treated with the help of infusion therapy, which is carried out simultaneously through two catheterized central veins.

Criteria, the patient's exit from a state of burn shock:

• stable stabilization of central hemodynamics;
• restoration of diuresis; elimination of hemoconcentration;
• the onset of fever.