Heat Stroke

Heat stroke is a serious condition characterized by general exhaustion and even faintness, caused by overheating of the body when thermoregulation is impaired, especially in people prone to vasomotor disorders and suffering from heart diseases, hyperthyroidism, obesity, insufficiency of the chromaffin system, and even from brief stays in excessively warm rooms or under direct sunlight. In hot weather and generally under prolonged exposure to high environmental temperatures, general overheating may be accompanied by an increase in body temperature, with cases of sudden death occurring, especially in children from heat exhaustion, and in adults from paralysis of the heart and cerebral hemorrhage. Humidity and stagnation of warm air reduce heat dissipation because evaporation from the body surface decreases, while high environmental temperatures in dry air with light clothing or even without clothing, especially with air movement, are much more easily tolerated due to greater heat loss through rapid evaporation of moisture from the body surface (perspiration, perspiratio insensibilis). Intense muscular work greatly contributes to rapid overheating as it sharply increases heat production, as well as tight and multi-layered clothing which significantly reduces heat dissipation. Intense nutrition, particularly excess proteins and fats in the diet serving as a source of increased heat formation, as established experimentally, predisposes to increased body temperature or even causes it (Fressfieber); insufficient water intake has the same effect (Durstfieber). Primarily affected are people performing intense prolonged muscular work in hot afternoon hours, even on cloudy days, and in enclosed rooms under unhygienic working conditions. Muscular work performed with full marching equipment when military units are moving on marches, maneuvers, etc., increases heat production 4-5 times (Schade), and marching clothing greatly reduces heat dissipation. The increase in body temperature due to overheating varies greatly among different people and is tolerated very differently, and with repeated exposure to overheating factors, it gradually decreases as acclimatization occurs due to improved thermoregulation. Therefore, people living in hot climates and working in hot workshops develop the ability to maintain body temperature at a normal level or at least tolerate increased temperature without particular disorders. However, if overheating persists and exceeds a certain degree, even acclimatized individuals experience decompensation of heat exchange, manifested as general exhaustion, headache, dizziness, fainting, convulsions, and even actual heat stroke. The difference between the conditions causing heat stroke and sunstroke consists mainly in that in the former, the primary cause is general overheating of the body regardless of the heat source, while in the latter, it is overheating of the head by solar radiation. Heat stroke is most frequently observed in tropical and subtropical climates, in areas located below 600 meters above sea level, but also in other zones during especially hot weather. Very indicative in this regard is a kind of heat stroke epidemic that broke out in the state of New York in August 1897 (Lambert). The air temperature in New York itself was 22-36.6°C (average 30.5°C) in the shade during the day, and 34.5-58.0°C (average 48.5°C) in the sun with no wind and air humidity up to 70%. Only 805 cases were registered in medical institutions, and Lambert, like other authors, distinguishes 3 degrees of the disease: 1) heat exhaustion (heat-prostration); there were 247 such cases in his material; 2) asphyxial form - 38 cases; 3) hyperpyretic form - 520 cases (492 men and 28 women), of which 132 were fatal. Symptoms of overheating: pain in the head, back, legs, epigastric region; profuse sweating (initially), often nausea, vomiting, even diarrhea; frequently darkening before the eyes or all objects appear colored red and green; breathing is difficult and rapid, heart palpitations and pronounced arterial pulsation are felt. Upon examination: redness and swelling of the face, rapid breathing and pulse, sometimes cyanosis and convulsive state without loss of consciousness; temperature is elevated to varying degrees, but may even be subnormal. This condition is characterized as heat exhaustion, and with more severe circulatory and respiratory disorders - as the asphyxial form. Heat stroke in the hyperpyretic form typically manifests as sudden loss of consciousness, with the patient falling while walking or during work; the skin is dry and hot due to cessation of sweating, or covered with scanty sticky sweat; often paleness and bluishness; pupils are often dilated and do not react to light; breathing is shallow and rapid (up to 50-64 per minute), sometimes irregular - Cheyne-Stokes; pulse is small and rapid (100-150 and even 180), not always corresponding to body temperature, which usually reaches 40.5°C and more, sometimes up to 43-45° and even 47.6°; often, especially when the body is cooled, it decreases significantly but may rise again; little urine is excreted or not at all. Muscle excitement in the form of twitching and convulsions or a comatose state is extremely characteristic. In general, the condition in heat stroke is very similar to that observed in sunstroke. Recovery with timely measures occurs in 70-80%, even with body temperature up to 45 and 46°C, but severe consequences are possible: neurasthenic state, coordination disorders, paralysis, epilepsy, melancholy, and even dementia. Death occurs in 20-30%, generally more often with hyperpyretic temperature, but often after temperature reduction, because the damage to the central nervous system caused by overheating is so profound that reducing temperature can no longer save the patient. Autopsy data: marked rigor mortis and rapid decomposition of the body; hyperemia of the meninges and brain, microchanges in chromaffin grains of ganglion cells, their decrease in number and partial disintegration, dark staining of their nuclei by van Gieson; hemorrhages along the nerve trunks; blood in vessels is liquid, not clotting; the heart is often in a state of marked muscular rigor; ecchymoses in the pericardium and pleura are characteristic; lungs are filled with blood. The pathogenesis of heat stroke is understood differently. The main cause of all disorders is, of course, external overheating, which in most cases leads to an increase in body temperature by 5-8° and even 10°. This is explained by the sharp decrease in heat dissipation in the period when sweating ceases, which is very characteristic of heat stroke and is caused by the enormous loss of water in the previous period; but the increase in temperature can also be explained by increased heat production due to muscular work and due to irritation of the heat center, i.e., a febrile state of central origin (Marchand). The thickening of blood in heat stroke due to decreased plasma volume and tissue dehydration is beyond doubt; the dry residue, as proven, increases by 12-15%, as a result of which the viscosity of blood increases greatly, and this undoubtedly impairs circulation, especially capillary; despite the increased heart contractions, already excited by overheating, circulation still occurs unsatisfactorily. Thus, oxygen consumption by tissues proves to be completely insufficient, i.e., there is an asphyxial state that can lead to death. During overheating, partial damage and dissolution of red blood cells are also assumed, but this phenomenon has not been sufficiently verified. Autointoxication, resulting from the retention of metabolic products whose excretion ceases together with the cessation of sweating and urination, may be significant as a cause of the comatose state in heat stroke victims, similar to the state in uremia; but retention of urine and sweat in the body without severe kidney damage does not yet lead to uremia. The poisoning effect of CO2 retained in the body due to circulatory and respiratory disorders is unlikely and in any case cannot be the cause of death. Poisoning with fibrin-ferment, which is supposedly formed in excess when the body overheats (Sanftleben), is unlikely. It is much more natural to recognize a violation of salt balance due to the loss of salts, particularly NaCl (chloropenia), by the body during profuse sweating, which usually precedes the cessation of sweating and urination in the comatose period. Thus, the pathological condition in heat stroke is caused by a series of profound, partly irreversible changes in the body under the influence of overheating, among which the most important is apparently paralysis of the higher brain centers. Prevention and treatment of heat stroke. When selecting people to work in hot workshops, it is necessary not to admit those with weakened constitutions, vasomotor disorders, obesity, and heart patients; the same applies when preparing for marches, maneuvers, competitions in hot weather. In very hot rooms, particularly in hot workshops, intensified ventilation is necessary.

For absorbing heat radiated by a flame or a hot surface, a device has been proposed in the form of a water curtain located in front of the heat source, formed by a continuous flow of many jets of cold water. Workers should wear the lightest porous clothing; work should be interrupted frequently, during which the body should be repeatedly cooled by pouring water over it, showers, baths, or in a common pool; abundant drinking is absolutely necessary—up to 15 liters per day, in particular carbonated salted water with NaCl content up to 0.6-1.0%, to replenish the huge loss of salt and water with perspiration and to increase diuresis; consumption of protein and fatty food should be limited, and alcoholic drinks even more so. Those exposed to overheating require systematic supervision. When symptoms of heat exhaustion appear, the victim should be immediately given rest or complete rest in a cooler place, and if possible, more vigorous cooling of the body and head (by fanning, water procedures), and given abundant cold or hot drinks, since the latter is taken more readily and causes more profuse perspiration. In heat stroke with unconsciousness and elevated body temperature, cooling of the body and head is especially important, and to increase the amount of fluid in the body and stimulate perspiration and diuresis—abundant subcutaneous or intravenous infusion of physiological or Ringer's solution or 1% hypersaline solution (when the pulse falls—better with adrenaline¹), as well as subcutaneous administration of camphor oil, caffeine, strychnine. In case of respiratory arrest—careful artificial respiration, lobelia 0.01 subcutaneously; in case of pulse arrest—heart massage, intracardial administration of adrenaline. In plethoric individuals, especially with a significant increase in blood pressure, bloodletting is indicated, and in cases of tense full pulse, even quite abundant (up to 0.5-1.0 liters), and reduction of intracranial pressure by lumbar puncture and leeches behind the ears. Lit.—see literature for the articles Sunstroke, Thermoregulation.