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Heat stroke or heatstroke, also known as sun stroke, is a severe heat illness that results in a
body temperature Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperatur ...
greater than , along with red skin, headache,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical ...
, and
confusion In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion"
.
Sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distri ...
is generally present in exertional heatstroke, but not in classic heatstroke. The start of heat stroke can be sudden or gradual. Heatstroke is a life-threatening condition due to the potential for multi-organ dysfunction, with typical complications including seizures, rhabdomyolysis, or kidney failure. Heat stroke occurs because of high external temperatures and/or physical exertion. It usually occurs under preventable prolonged exposure to extreme environmental or exertional heat. However, certain health conditions can increase the risk of heat stroke, and patients, especially children, with certain genetic predispositions are vulnerable to heatstroke under relatively mild conditions. Preventive measures include drinking sufficient fluids and avoiding excessive heat. Treatment is by rapid physical cooling of the body and supportive care. Recommended methods include spraying the person with water and using a fan, putting the person in ice water, or giving cold
intravenous fluids Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...
. Adding ice packs around a person is reasonable but does not by itself achieve the fastest possible cooling. Heat stroke results in more than 600 deaths a year in the United States. Rates have increased between 1995 and 2015. Purely exercise-induced heat stroke, though a medical emergency, tends to be self-limiting (the patient stops exercising from cramp or exhaustion) and fewer than 5% of cases are fatal. Non-exertional heatstroke is a much greater danger: even the healthiest person, if left in a heatstroke-inducing environment without medical attention, will continue to deteriorate to the point of death, and 65% of the most severe cases are fatal even with treatment.


Signs and symptoms

Heat stroke generally presents with a hyperthermia of greater than in combination with disorientation. However, high body temperature does not necessarily indicate that heat stroke is present, such as with people in high-performance endurance sports or with people experiencing fevers. Exertional heat stroke is more accurately diagnosed based on a constellation of symptoms rather than just a specific temperature threshold. There is generally a lack of
sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distri ...
in classic heatstroke, while sweating is generally present in exertional heatstroke. Early symptoms of heat stroke include behavioral changes, confusion,
delirium Delirium (also known as acute confusional state) is an organically caused decline from a previous baseline of mental function that develops over a short period of time, typically hours to days. Delirium is a syndrome encompassing disturbances ...
,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical ...
, weakness, agitation, combativeness, slurred speech,
nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
, and vomiting. In some individuals with exertional heatstroke, seizures and sphincter incontinence have also been reported. Additionally, in exertional heat stroke, the affected person may sweat excessively. If treatment is delayed, patients could develop vital organ damage,
unconsciousness Unconsciousness is a state in which a living individual exhibits a complete, or near-complete, inability to maintain an awareness of self and environment or to respond to any human or environmental stimulus. Unconsciousness may occur as the r ...
and even organ failure. In the absence of prompt and adequate treatment, heatstroke can be fatal.


Causes

Heat stroke occurs when thermoregulation is overwhelmed by a combination of excessive
metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cel ...
production of heat (exertion), excessive heat in the physical environment, and insufficient or impaired heat loss, resulting in an abnormally high body temperature. Substances that inhibit cooling and cause dehydration such as alcohol, stimulants, medications, and age-related physiological changes predispose to so-called "classic" or non-exertional heat stroke (NEHS), most often in elderly and infirm individuals in summer situations with insufficient ventilation.


Exertional heat stroke

Exertional heat stroke (EHS) can happen in young people without health problems or medications most often in
athlete An athlete (also sportsman or sportswoman) is a person who competes in one or more sports that involve physical strength, speed, or endurance. Athletes may be professionals or amateurs. Most professional athletes have particularly well-dev ...
s, outdoor laborers, or
military personnel Military personnel are members of the state's armed forces. Their roles, pay, and obligations differ according to their military branch (army, navy, marines, air force, space force, and coast guard), rank ( officer, non-commissioned officer, ...
engaged in strenuous hot-weather activity or in
first responder A first responder is a person with specialized training who is among the first to arrive and provide assistance or incident resolution at the scene of an emergency, such as an accident, disaster, medical emergency, structure fire, crime, or ...
s wearing heavy
personal protective equipment Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, ...
. In environments that are not only hot but also humid, it is important to recognize that
humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...
reduces the degree to which the body can cool itself by perspiration and evaporation. For humans and other
warm-blooded Warm-blooded is an informal term referring to animal species which can maintain a body temperature higher than their environment. In particular, homeothermic species maintain a stable body temperature by regulating metabolic processes. The on ...
animals, excessive body temperature can disrupt enzymes regulating biochemical reactions that are essential for cellular respiration and the functioning of major organs.


Cars

When the outside temperature is , the temperature inside a car parked in direct sunlight can quickly exceed . Young children or elderly adults left alone in a vehicle are at particular risk of succumbing to heat stroke. "Heat stroke in children and in the elderly can occur within minutes, even if a car window is opened slightly." As these groups of individuals may not be able to open car doors or to express discomfort verbally (or audibly, inside a closed car), their plight may not be immediately noticed by others in the vicinity. In 2018, 51 children in the United States died in hot cars, more than the previous high of 49 in 2010. Dogs are even more susceptible than humans to heat stroke in cars, as they cannot produce whole-body sweat to cool themselves. Leaving the dog at home with plenty of water on hot days is recommended instead, or, if a dog must be brought along, it can be
tied up "Tied Up" is a song recorded by English-born Australian singer Olivia Newton-John for her second greatest hits album ''Olivia's Greatest Hits Vol. 2'' (1982). Written by John Farrar and Lee Ritenour, and produced by the former, the song was t ...
in the shade outside the destination and provided with a full water bowl.


Pathophysiology

The pathophysiology of heat stroke involves an intense heat overload followed by a failure of the body's thermoregulatory mechanisms. More specifically, heat stroke leads to inflammatory and
coagulation Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...
responses that can damage the
vascular endothelium Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from t ...
and result in numerous platelet complications, including decreased platelet counts, platelet clumping, and suppressed platelet release from bone marrow. Growing evidence also suggests the existence of a second pathway underlying heat stroke that involves heat and exercise-driven endotoxemia. Although its exact mechanism is not yet fully understood, this model theorizes that extreme exercise and heat disrupt the intestinal barrier by making it more permeable and allowing lipopolysaccharides (LPS) from gram-negative bacteria within the gut to move into the circulatory system. High blood LPS levels can then trigger a systemic inflammatory response and eventually lead to
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is foll ...
and related consequences like blood coagulation, multi-organ failure, necrosis, and central nervous system dysfunction.


Diagnosis

In terms of the diagnosis for this condition one sees the following (though this is not a complete list): * CBC * PT/PTT * Blood gases * Urine test


Prevention

The risk of heat stroke can be reduced by observing precautions to avoid overheating and dehydration. Light, loose-fitting clothes will allow perspiration to evaporate and cool the body. Wide-brimmed hats in light colors help prevent the sun from warming the head and neck. Vents on a hat will help cool the head, as will sweatbands wetted with cool water. Strenuous exercise should be avoided during hot weather, especially in the sun peak hours as well as avoiding confined spaces (such as automobiles) without air-conditioning or adequate ventilation. In hot weather, people need to drink plenty of cool liquids and mineral salts to replace fluids lost from
sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distri ...
. Thirst is not a reliable sign that a person needs fluids. A better indicator is the color of
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...
. A dark yellow color may indicate dehydration. Example of a checklist designed to help protect workers from heat stress: * Know signs/symptoms of heat-related illnesses. * Block out direct sun and other heat sources. * Drink fluids often, and ''before'' you are thirsty. * Wear lightweight, light-colored, loose-fitting clothes. * Avoid beverages containing alcohol or caffeine.


Treatment

Treatment of heat stroke involves rapid mechanical cooling along with standard resuscitation measures. The body temperature must be lowered quickly via conduction,
convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...
, or evaporation. The person should be moved to a cool area, such as indoors or to a shaded area. Clothing should be removed to promote heat loss through passive cooling. Conductive cooling methods such as ice-water immersion should also be used, if possible. Evaporative and convective cooling by a combination of cool water spray or cold compresses with constant air flow over the body, such as with a fan or air-conditioning unit, is also an effective alternative. The person should not be wrapped in wet towels or clothing as this can act as insulation and increase the body temperature. Aggressive ice-water immersion remains the
gold standard A gold standard is a Backed currency, monetary system in which the standard economics, economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the ...
for life-threatening heat stroke. This method may require the effort of several people and the person should be monitored carefully during the treatment process. Immersion should be avoided for an unconscious person, but if there is no alternative, the person's head must be held above water. Immersion in very cold water was once thought to be counterproductive by reducing blood flow to the skin and thereby preventing heat from escaping the body core. However, research has shown that this mechanism does not play a dominant role in the decrease in core body temperature brought on by cold water. Dantrolene, a muscle relaxant used to treat other forms of hyperthermia, is not an effective treatment for heat stroke. Hydration is important in cooling the person. In mild cases of concomitant dehydration, this can be achieved by drinking water, or commercial isotonic
sports drink Sports drinks, also known as electrolyte drinks, are functional beverages whose stated purpose is to help athletes replace water, electrolytes, and energy before, during and especially after training or competition. There are many perceived be ...
s may be used as a substitute. In either exercise- or heat-induced dehydration,
electrolyte imbalance Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function ...
can result, and can be worsened by excess consumption of water.
Hyponatremia Hyponatremia or hyponatraemia is a low concentration of sodium in the blood. It is generally defined as a sodium concentration of less than 135  mmol/L (135  mEq/L), with severe hyponatremia being below 120 mEq/L. Symptoms can be a ...
can be corrected by intake of hypertonic fluids. Absorption is rapid and complete in most people but if the person is confused, unconscious, or unable to tolerate oral fluid, then an
intravenous drip Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutri ...
may be necessary for rehydration and electrolyte replacement. The person's condition should be reassessed and stabilized by trained medical personnel. The person's heart rate and breathing should be monitored, and
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spon ...
(CPR) may be necessary if the person goes into
cardiac arrest Cardiac arrest is when the heart suddenly and unexpectedly stops beating. It is a medical emergency that, without immediate medical intervention, will result in sudden cardiac death within minutes. Cardiopulmonary resuscitation (CPR) and possib ...
.


Prognosis

It was long believed that heat strokes lead only rarely to permanent deficits and that convalescence is almost complete. However, following the
1995 Chicago heat wave The July 1995 Chicago heat wave led to 739 heat-related deaths in Chicago over a period of five days. Most of the victims of the heat wave were elderly poor residents of the city, who could not afford air conditioning and did not open windows or ...
, researchers from the University of Chicago Medical Center studied all 58 patients with heat stroke severe enough to require intensive care at 12 area hospitals between July 12 and 20, 1995, ranging in age from 25 to 95 years. Nearly half of these patients died within a year 21 percent before and 28 percent after release from the hospital. Many of the survivors had permanent loss of independent function; one-third had severe functional impairment at discharge, and none of them had improved after one year. The study also recognized that because of overcrowded conditions in all the participating hospitals during the crisis, the immediate care which is critical was not as comprehensive as it should have been. In rare cases, brain damage has been reported as a permanent sequela of severe heat stroke, most commonly cerebellar atrophy.


Epidemiology

There are various aspects that can affect the incidence of heat stroke. Including sex, age, geographical location, and even occupation. The incidence of heat stroke is higher among men however, the incidence of other heat illnesses is higher among women. The incidence of other heat illnesses in women compared with men ranged from 1.30 to 2.89 per 1000 person-years versus 0.98 to 1.98 per 1000 person-years. Different parts of the world also have different rates of heat stroke. During the
2022 European heat wave From June to August 2022, persistent heatwaves affected parts of Europe, causing evacuations and over 20,000 heat-related deaths, making these heat waves the deadliest meteorological events in 2022. The highest temperature recorded was in P ...
, almost twelve thousand people died from heatstrokes.


Society and culture

In Slavic
mythology Myth is a folklore genre consisting of Narrative, narratives that play a fundamental role in a society, such as foundational tales or Origin myth, origin myths. Since "myth" is widely used to imply that a story is not Objectivity (philosophy), ...
, there is a personification of sunstroke, Poludnitsa (lady midday), a feminine demon clad in white that causes impairment or death to people working in the fields at midday. There was a traditional short break in
harvest Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most lab ...
work at noon, to avoid attack by the demon.
Antonín Dvořák Antonín Leopold Dvořák ( ; ; 8 September 1841 – 1 May 1904) was a Czech composer. Dvořák frequently employed rhythms and other aspects of the folk music of Moravia and his native Bohemia, following the Romantic-era nationalist exampl ...
's symphonic poem, '' The Noon Witch'', was inspired by this tradition.


Other animals

Heatstroke can affect livestock, especially in hot, humid weather; or if the horse, cow, sheep or other is unfit, overweight, has a dense coat, is overworked, or is left in a horsebox in full sun. Symptoms include drooling, panting, high temperature, sweating, and rapid pulse. The animal should be moved to shade, drenched in cold water and offered water or electrolyte to drink.
Horse and Hound ''Horse & Hound'' is the oldest equestrian weekly magazine of the United Kingdom. Its first edition was published in 1884. The magazine contains horse industry news, reports from equestrian events, veterinary advice about caring for horses, and h ...
, 'First Aid: Handling Heatstroke', 2/8/2004


See also

*
Hyperthermia Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...
* Heat exhaustion * Occupational heat stress


References


External links


Heat stroke
on MedicineNet.com {{DEFAULTSORT:Heat stroke Deaths from hyperthermia Effects of external causes Medical emergencies Wikipedia medicine articles ready to translate Wikipedia emergency medicine articles ready to translate Thermoregulation