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Heatstroke: First Aid
Last reviewed: 23.04.2024
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Thermal shock is hyperthermia accompanied by a systemic inflammatory reaction that causes multiple organ failure and often death. Heat stroke is manifested by an increase in body temperature above 40 ° C and a violation of mental state; sweating is often absent. The diagnosis is based on clinical data. First aid for heat stroke includes rapid external cooling of the body, intravenous fluids and maintenance measures required for organ failure.
Thermal shock occurs when the thermoregulatory mechanisms cease to function and the body temperature increases significantly. As a result of the activation of inflammatory cytokines, multiple organ dysfunction may develop. A role can play endotoxins of the gastrointestinal tract. Functional deficiency of the central nervous system, skeletal muscles (rhabdomyolysis), liver, kidneys, lungs (acute respiratory distress syndrome) and the heart are possible. The coagulation cascade, sometimes causing the syndrome of disseminated intravascular coagulation, is activated. Perhaps the development of hyperkalemia and hypoglycemia.
There are two versions of thermal shock: classical and due to overvoltage. Classical heat stroke develops within 2-3 days, is more frequent in the summer, in hot weather, usually in the elderly, inactive people living without an air conditioner, often with limited access to water. The classic heat stroke caused many deaths in an unusually hot summer in Europe in 2003.
Heat shock due to overexertion occurs suddenly in healthy, active people (for example, athletes, recruits, factory workers). Heavy physical work in the heat conditions leads to a sudden massive heat load, which the body can not compensate. Rhabdomyolysis often develops, severe coagulopathy and kidney failure are possible.
A similar heat stroke syndrome can be observed with certain drugs (for example, cocaine, phencyclidine, amphetamines, monoamine oxidase inhibitors). To do this, in most cases an overdose is needed; additional physical stress or environmental conditions, can cause impact without it. In response to the administration of certain anesthetics and neuroleptics, malignant hyperthermia is possible (see the appropriate section). This is a genetically determined disease, with a high incidence of deaths.
Symptoms of heat stroke
The main symptom is central nervous system dysfunction, ranging from confusion to delirium, seizures and coma. Characterized by tachypnea, even in the position on the back, and tachycardia. With a classic thermal shock, the skin is hot and dry, and with the second option - there is increased sweating. In both cases, body temperature> 40 ° C, can exceed 46 ° C.
Diagnosis of heat stroke
The diagnosis is usually obvious, especially if there is evidence of physical activity and heat. However, if it is known about the absence of an extreme situation, it is necessary to exclude acute infectious disease (eg, meningitis, sepsis) and toxic shock. It should also be clarified the possibility of taking drugs that can cause this condition.
The laboratory study includes a clinical blood test, the definition of the prothrombin index, partial thromboplastin time, the concentration of electrolytes, urea, creatinine, CK and hepatic profile for the evaluation of organ function. Establish a urinary catheter, urine is examined for latent blood, a drug test can help. The test for the presence of myoglobin in the urine is not necessary. It is necessary to constantly monitor the body temperature, preferably with a rectal or esophageal sensor.
Forecast and first aid for heat shock
With a thermal shock, a high incidence of mortality is noted, varying depending on age, concomitant pathology, maximum body temperature and most of all on the duration of hyperthermia and the rate of cooling. Approximately 20 % of survivors have residual CNS disorders. Some patients may persist with renal failure. Body temperature remains unstable for several weeks.
Rapid recognition and effective, aggressive cooling are of great importance. Methods that do not cause shivering and vasoconstriction of the skin are preferred, although ice bubbles or dipping of the victim into ice water are effective enough. Evaporative cooling is comfortable for the patient, convenient, and some experts consider it to be the fastest. The patient is continuously moistened with water, the skin is blown and massaged vigorously to increase blood flow. It is best to use a spray hose and a large fan for this, which can be used for large groups of victims in the field. It is sufficient to use warm water (about 30 ° C), since evaporation itself causes cooling; cold or icy water is not needed. To help on the spot, you can put the victim in a regular pond. Bleaches with ice on the inguinal and axillary areas can be used, but only as an additional method. In cases that are life-threatening, to rapidly reduce body temperature in the conditions of careful monitoring, the patient is literally "packaged" in ice.
Begin intravenous rehydration with a 0.9% solution of sodium chloride (as described in the corresponding section), treatment of multiple organ failure and rhabdomyolysis. To prevent excitation and seizures (increasing heat production), injectable benzodiazepines (lorazepam or diazepam) can be used; during the cooling, cramps are possible. It is necessary to take measures to protect the respiratory tract, since vomiting and aspiration of vomit are possible. With a strong excitation, the introduction of muscle relaxants and artificial ventilation of the lungs are indicated.
With expressed disseminated intravascular coagulation, transfusions of platelets and freshly frozen plasma may be required. In myoglobinuria for alkalinizing urine and preventing nephrotoxicity intravenously sodium bicarbonate is administered. Intravenous administration of calcium salts may be required to treat hyperkalemic cardiotoxicity. Vasoconstrictors, commonly used to treat arterial hypotension, can reduce the rate of cutaneous blood flow and slow down the cooling. You may need hemodialysis. Antipyretics (for example, paracetamol) are useless. In the treatment of malignant hyperthermia caused by anesthetics, dantrolene is used, but its effectiveness in the treatment of other forms of heat disease has not been proven.