Heat illness

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Heat stroke treatment at Baton Rouge during 2016 Louisiana floods Heat stroke treatment, Baton Rouge, 2016 Louisiana floods.jpg
Heat stroke treatment at Baton Rouge during 2016 Louisiana floods
Heat exhaustion
Other namesHeat-related illness
Specialty Emergency medicine

Heat illness is a spectrum of disorders due to increased body temperature. It can be caused by either environmental conditions or by exertion. It includes minor conditions such as heat cramps, heat syncope, and heat exhaustion as well as the more severe condition known as heat stroke. [1] It can affect any or all anatomical systems. [2] Heat illnesses include: [3] [4] heat stroke, heat exhaustion, heat syncope, heat edema, heat cramps, heat rash, heat tetany.

Contents

Prevention includes avoiding medications that can increase the risk of heat illness, gradual adjustment to heat, and sufficient fluids and electrolytes. [5] [6]

Classification

A number of heat illnesses exist including: [3] [4]

Overview of diseases

Hyperthermia, also known as heat stroke, becomes commonplace during periods of sustained high temperature and humidity. [9] Older adults, very young children, and those who are sick or overweight are at a higher risk for heat-related illness. [10] The chronically ill and elderly are often taking prescription medications (e.g., diuretics, anticholinergics, antipsychotics, and antihypertensives) that interfere with the body's ability to dissipate heat. [11]

Heat edema presents as a transient swelling of the hands, feet, and ankles and is generally secondary to increased aldosterone secretion, which enhances water retention. When combined with peripheral vasodilation and venous stasis, the excess fluid accumulates in the dependent areas of the extremities. The heat edema usually resolves within several days after the patient becomes acclimated to the warmer environment. No treatment is required, although wearing support stockings and elevating the affected legs will help minimize the edema. [12]

Heat rash, also known as prickly heat, is a maculopapular rash accompanied by acute inflammation and blocked sweat ducts. The sweat ducts may become dilated and may eventually rupture, producing small pruritic vesicles on an erythematous base. Heat rash affects areas of the body covered by tight clothing. If this continues for a duration of time it can lead to the development of chronic dermatitis or a secondary bacterial infection. Prevention is the best therapy. It is also advised to wear loose-fitting clothing in the heat. Once heat rash has developed, the initial treatment involves the application of chlorhexidine lotion to remove any desquamated skin. The associated itching may be treated with topical or systemic antihistamines. If infection occurs a regimen of antibiotics is required. [13]

Heat cramps are painful, often severe, involuntary spasms of the large muscle groups used in strenuous exercise. Heat cramps tend to occur after intense exertion. [14] They usually develop in people performing heavy exercise while sweating profusely and replenishing fluid loss with non-electrolyte containing water. This is believed to lead to hyponatremia that induces cramping in stressed muscles. Rehydration with salt-containing fluids provides rapid relief. Patients with mild cramps can be given oral .2% salt solutions, while those with severe cramps require IV isotonic fluids. The many sport drinks on the market are a good source of electrolytes and are readily accessible.

Heat syncope is related to heat exposure that produces orthostatic hypotension. This hypotension can precipitate a near-syncopal episode. Heat syncope is believed to result from intense sweating, which leads to dehydration, followed by peripheral vasodilation and reduced venous blood return in the face of decreased vasomotor control. Management of heat syncope consists of cooling and rehydration of the patient using oral rehydration therapy (sport drinks) or isotonic IV fluids. People who experience heat syncope should avoid standing in the heat for long periods of time. They should move to a cooler environment and lie down if they recognize the initial symptoms. Wearing support stockings and engaging in deep knee-bending movements can help promote venous blood return. [15]

Heat exhaustion is considered by experts to be the forerunner of heat stroke (hyperthermia). It may even resemble heat stroke, with the difference being that the neurologic function remains intact. Heat exhaustion is marked by excessive dehydration and electrolyte depletion. Symptoms may include diarrhea, headache, nausea and vomiting, dizziness, tachycardia, malaise, and myalgia. Definitive therapy includes removing patients from the heat and replenishing their fluids. Most patients will require fluid replacement with IV isotonic fluids at first. The salt content is adjusted as necessary once the electrolyte levels are known. After discharge from the hospital, patients are instructed to rest, drink plenty of fluids for 2–3 hours, and avoid the heat for several days. If this advice is not followed it may then lead to heat stroke. [16]

Symptoms

Increased temperatures have been reported to cause heat stroke, heat exhaustion, heat syncope, and heat cramps. [17] Some studies have also looked at how severe heat stroke can lead to permanent damage to organ systems. [17] This damage can increase the risk of early mortality because the damage can cause severe impairment in organ function. [17] Other complications of heat stroke include respiratory distress syndrome in adults and disseminated intravascular coagulation. [18] Some researchers have noted that any compromise to the human body's ability to thermoregulate would in theory increase risk of mortality. [17] This includes illnesses that may affect a person's mobility, awareness, or behavior. [17]

Prevention

Prevention includes avoiding medications that can increase the risk of heat illness (e.g. antihypertensives, diuretics, and anticholinergics), gradual adjustment to heat, and sufficient fluids and electrolytes. [5] [6]

Some common medications that have an effect on thermoregulation can also increase the risk of mortality. Specific examples include anticholinergics, [17] diuretics, [17] phenothiazines [18] and barbiturates. [18]

Epidemiology

Heat stroke is relatively common in sports. About 2 percent of sports-related deaths that occurred in the United States between 1980 and 2006 were caused by exertional heat stroke. [19] Football in the United States has the highest rates. [19] The month of August, which is associated with pre-season football camps across the country, accounts for 66.3% of exertion heat-related illness time-loss events. [20] Heat illness is also not limited geographically and is widely distributed throughout the United States. [21] An average of 5946 persons were treated annually in US hospital emergency departments (2 visits/ 100,00 population) with a hospitalization rate of 7.1%. [20] Most commonly males are brought in 72.5% and persons 15–19 years of age 35.6% [20] When taking into consideration all high school athletes, heat illness occurs at a rate of 1.2 per 100,000 kids. [21] When comparing risk by sport, Football was 11.4 times more likely than all other sports combined to be exposed to an exertional heat illness. [21]

Between 1999 and 2003, the US had a total of 3442 deaths from heat illness. Those who work outdoors are at particular risk for heat illness, though those who work in poorly-cooled spaces indoors are also at risk. Between 1992 and 2006, 423 workers died from heat illness in the US. [6] Exposure to environmental heat led to 37 work-related deaths. There were 2,830 nonfatal occupational injuries and illnesses involving days away from work as well, in 2015. [22] Kansas had the highest heat related injury while on the job with a rate of 1.3 per 10,000 workers, while Texas had the most overall. [22] Due to the much higher state population of Texas, their prevalence was only 0.4 per 10,000 or 4 per 100,000. Of the 37 deaths reported heat illnesses, 33 of the 37 occurred between the summer months of June through September. The most dangerous profession that was documented was transportation and material moving. [22] Transportation and material moving accounted for 720 of the 2,830 reported nonfatal occupational injuries or 25.4 percent. [22] After transportation and material moving, Production placed second followed by protective services, installation, maintenance, and repair and construction all in succession [22]

Effects of climate change

A 2016 U.S. government report said that climate change could result in "tens of thousands of additional premature deaths per year across the United States by the end of this century." [23] Indeed, between 2014 and 2017, heat exposure deaths tripled in Arizona (76 deaths in 2014; 235 deaths in 2017) and increased fivefold in Nevada (29 deaths in 2014; 139 deaths in 2017). [24]

History

Heat illness used to be blamed on a tropical fever named calenture. [25]

See also

Related Research Articles

<span class="mw-page-title-main">Hyperthermia</span> Elevated body temperature due to failed thermoregulation

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 temperature elevation occurs, it becomes a medical emergency requiring immediate treatment to prevent disability or death. Almost half a million deaths are recorded every year from hyperthermia.

<span class="mw-page-title-main">Diabetic coma</span> Medical condition

Diabetic coma is a life-threatening but reversible form of coma found in people with diabetes mellitus.

<span class="mw-page-title-main">Dehydration</span> Deficit of total body water

In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mild dehydration can also be caused by immersion diuresis, which may increase risk of decompression sickness in divers.

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 absent, mild or severe. Mild symptoms include a decreased ability to think, headaches, nausea, and poor balance. Severe symptoms include confusion, seizures, and coma; death can ensue.

<span class="mw-page-title-main">Fluid replacement</span>

Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced with oral rehydration therapy (drinking), intravenous therapy, rectally such as with a Murphy drip, or by hypodermoclysis, the direct injection of fluid into the subcutaneous tissue. Fluids administered by the oral and hypodermic routes are absorbed more slowly than those given intravenously.

<span class="mw-page-title-main">Cerebral edema</span> Excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain

Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compression of brain tissue and blood vessels. Symptoms vary based on the location and extent of edema and generally include headaches, nausea, vomiting, seizures, drowsiness, visual disturbances, dizziness, and in severe cases, death.

Heat exhaustion is a severe form of heat illness. It is a medical emergency. Heat exhaustion is caused by the loss of water and electrolytes through sweating.

<span class="mw-page-title-main">Electrolyte imbalance</span> Medical condition

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, fluid balance, oxygen delivery, acid–base balance and much more. Electrolyte imbalances can develop by consuming too little or too much electrolyte as well as excreting too little or too much electrolyte. Examples of electrolytes include calcium, chloride, magnesium, phosphate, potassium, and sodium.

<span class="mw-page-title-main">Water intoxication</span> Potentially fatal overhydration

Water intoxication, also known as water poisoning, hyperhydration, overhydration, water toxemia or hyponatremia is a potentially fatal disturbance in brain functions that can result when the normal balance of electrolytes in the body is pushed outside safe limits by excessive water intake.

<span class="mw-page-title-main">Miliaria</span> Medical condition

Miliaria, commonly known as heat rash, sweat rash, or prickly heat, is a skin disease marked by small, itchy rashes due to sweat trapped under the skin by clogged sweat-gland ducts. Miliaria is a common ailment in hot and humid conditions, such as in the tropics and during the summer. Although it affects people of all ages, it is especially common in children and infants due to their underdeveloped sweat glands.

Heat is energy in transfer to or from a thermodynamic system by mechanisms other than thermodynamic work or transfer of matter.

Diving disorders, or diving related medical conditions, are conditions associated with underwater diving, and include both conditions unique to underwater diving, and those that also occur during other activities. This second group further divides into conditions caused by exposure to ambient pressures significantly different from surface atmospheric pressure, and a range of conditions caused by general environment and equipment associated with diving activities.

Lightheadedness is a common and typically unpleasant sensation of dizziness or a feeling that one may faint. The sensation of lightheadedness can be short-lived, prolonged, or, rarely, recurring. In addition to dizziness, the individual may feel as though their head is weightless. The individual may also feel as though the room is "spinning" or moving (vertigo). Most causes of lightheadedness are not serious and either cure themselves quickly or are easily treated.

<span class="mw-page-title-main">Heat syncope</span> Medical condition

Heat syncope is fainting or dizziness as a result of overheating. It is a type of heat illness. The basic symptom of heat syncope is fainting, with or without mental confusion. Heat syncope is caused by peripheral vessel dilation, resulting in diminished blood flow to the brain and dehydration.

In medicine, intravascular volume status refers to the volume of blood in a patient's circulatory system, and is essentially the blood plasma component of the overall volume status of the body, which otherwise includes both intracellular fluid and extracellular fluid. Still, the intravascular component is usually of primary interest, and volume status is sometimes used synonymously with intravascular volume status.

Heat cramps, a type of heat illness, are muscle spasms that result from loss of large amount of salt and water through exercise. Heat cramps are associated with cramping in the abdomen, arms and calves. This can be caused by inadequate consumption of fluids or electrolytes. Heavy sweating causes heat cramps, especially when the water is replaced without also replacing salt or potassium.

<span class="mw-page-title-main">Syncope (medicine)</span> Transient loss of consciousness and postural tone

Syncope, commonly known as fainting or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from low blood pressure. There are sometimes symptoms before the loss of consciousness such as lightheadedness, sweating, pale skin, blurred vision, nausea, vomiting, or feeling warm. Syncope may also be associated with a short episode of muscle twitching. Psychiatric causes can also be determined when a patient experiences fear, anxiety, or panic; particularly before a stressful event, usually medical in nature. When consciousness and muscle strength are not completely lost, it is called presyncope. It is recommended that presyncope be treated the same as syncope.

<span class="mw-page-title-main">Heat stroke</span> Condition caused by excessive exposure to high temperatures.

Heat stroke or heatstroke, also known as sun-stroke, is a severe heat illness that results in a body temperature greater than 40.0 °C (104.0 °F), along with red skin, headache, dizziness, and confusion. Sweating 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.

<span class="mw-page-title-main">Health issues in youth sports</span>

The health issues of youth sports are concerns regarding the health and wellbeing of young people between the ages of 6 and 18 who participate in an organized sport. Given that these athletes are physically and mentally underdeveloped, they are particularly susceptible to heat illness, eating disorders and injury; sufficiently severe conditions can result in death. Awareness and prevention are key factors in preventing many health issues in youth sports.

Occupational heat stress is the net load to which a worker is exposed from the combined contributions of metabolic heat, environmental factors, and clothing worn which results in an increase in heat storage in the body. Heat stress can result in heat-related illnesses, such as heat stroke, hyperthermia, heat exhaustion, heat cramps, heat rashes and chronic kidney disease. Although heat exhaustion is less severe, heat stroke is a medical emergency and requires emergency treatment, which if not provided can even lead to death.

References

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  2. ↑ Morca, Camilo; Counsell, Bielecki, Louis (November 2017), "Twenty-Seven Ways a Heat Wave Can Kill You: Deadly Heat in the Era of Climate Change", Cardiovascular Quality and Outcomes, 10 (11), doi: 10.1161/CIRCOUTCOMES.117.004233 , PMID   29122837 {{citation}}: CS1 maint: multiple names: authors list (link)
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  6. 1 2 3 Jacklitsch, Brenda L. (June 29, 2011). "Summer Heat Can Be Deadly for Outdoor Workers". NIOSH: Workplace Safety and Health. Medscape and NIOSH. Archived from the original on December 4, 2012.
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  8. ↑ Archived July 21, 2010, at the Wayback Machine
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  13. ↑ "Heat rash - Symptoms & causes - Mayo Clinic". www.mayoclinic.org. Retrieved 2023-09-20.
  14. ↑ "Heat Cramps, First Aid Condition, Treatments and Pictures for". Skinsight. 2022-08-16. Retrieved 2023-09-20.
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  16. ↑ Kenny, Glen P.; Wilson, Thad E.; Flouris, Andreas D.; Fujii, Naoto (2018). "Heat exhaustion". Handbook of Clinical Neurology. 157: 505–529. doi:10.1016/B978-0-444-64074-1.00031-8. ISSN   0072-9752. PMID   30459023.
  17. 1 2 3 4 5 6 7 Kovats, R. Sari; Hajat, Shakoor (April 2008). "Heat Stress and Public Health: A Critical Review". Annual Review of Public Health. 29 (1): 41–55. doi: 10.1146/annurev.publhealth.29.020907.090843 . PMID   18031221.
  18. 1 2 3 Koppe, Christina; Sari Kovats; Gerd Jendritzky; Bettina Menne (2004). "Heat-waves: risks and responses". Health and Global Environmental Change Series. 2.
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  25. ↑ "Calenture: the free dictionary". thefreedictionary.com. Retrieved 2016-01-26.
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