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Heatstroke

Dr. Sachin Shelke
Internal Medicine

verified

Our body regulates its temperature by itself. When the body gets hotter, it cools down by sweating and increased breathing and many other ways. But when someone remains in a hot environment without consuming sufficient fluid, the body may not work on the cooling process properly. This leads to a higher than normal temperature of the body. This condition is called heat illness. The primary symptoms of heat illness are a rise in body temperature accompanied by nausea, headache, vomiting, fatigue, and muscle cramps. These primary symptoms are sometimes referred to as heat exhaustion. If heat exhaustion is not treated properly and remains ignored, it can make the person sicker. This condition is called heatstroke.

Heatstroke is a serious condition characterized by an increased body temperature (hyperthermia; >40oC) that may lead to central nervous system dysfunction. The resulting outcomes are mental disabilities, shortness of breath, convulsions (uncontrollable muscle contractions), or coma (lack of consciousness). Even after hypothermia (cooling down the body temperature) or other treatments, heatstroke may result in death. Other consequences of heatstroke are toxicity to cells and organs in the entire body, kidney failure, breakdown of muscle cells, liver cells damage, heart attack, brain swelling, and various metabolic abnormalities. Heatstroke is a very complicated process, and if any symptom of heat exhaustion is found, one should visit a doctor immediately.[1-3]

TYPES

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Heatstroke is categorised into two forms:[3,4]

Non-exertional stroke: This is also known as classic heatstroke. It is more commonly seen in the elderly who are not able to adjust in hot environments due to the age factor, and in persons who are having long-term illnesses. The death rate in these patients due to heatstroke is high. It develops over several days. The typical symptoms of classic heatstroke included dry skin, nausea, headache, vomiting, and deteriorating mental health. Young children are also at the risk of having classic heatstroke.

Exertional heatstroke: It is a situation in which an individual needs a medical emergency treatment. It generally develops in the young ones who exercise vigorously and have not adapted to a hot environment. A dramatic presentation of central nervous system alterations is seen, from severe headaches to seizures (a sudden and uncontrolled disturbance in the brain) and collapse. This further leads to the breakdown of muscle tissues and protein release in the blood, which causes kidney failure. Exertional heatstroke can occur within one hour of exertion and can be accelerated without exposure to high temperatures. Most of the time, it remains misdiagnosed. The typical symptoms of exertional heatstroke are wet skin and profuse sweating.

Symptoms

The following are the most common symptoms of heatstroke. However, each individual may experience symptoms differently. Below are the symptoms of heatstroke:[5,6]


  1. Headache

  2. Nausea or vomiting

  3. Intense thirst

  4. Dizziness

  5. Disorientation, confusion, or agitation

  6. Sluggishness or fatigue

  7. Seizure

  8. Hot, dry and red skin that is flushed but no sweat

  9. A high body temperature

  10. Coma (loss of consciousness)

  11. Rapid heartbeat

  12. Hallucinations (sensing things like sounds, visions, or smells that seem actual but in reality, these are not real)

  13. Very high body temperature

  14. Fatal if treatment delayed

  15. Rapid pulse and fast, shallow breathing

  16. Trouble in speaking, slurred speech

  17. Problems in concentrating or coordinating movements

  18. Aggressive or strange behaviour

  19. Dry swollen tongue

Causes And Risk Factors

Heatstroke can affect any person, but more risk is for them: [6,7]


  1. People more than 65 years of age, living in the hotter environments without air conditioning

  2. Young children

  3. Pregnant and breast-feeding mothers

  4. People having other medical conditions, especially high blood pressure, heart disease, or lung disease

  5. People on medications for neurological disorders

  6. Athletes with a history of exertional heatstroke, inadequate heat adaptation, low fitness level, overweight or obesity, insufficient hydration, lack of sleep, intense or prolonged exercise with minimal breaks

  7. High temperature/humidity/sun exposure

  8. Lack of awareness and education about heat illness among athletes, coaches, and medical staff

  9. Limited or no access to fluids or breaks while taking part in sports or other activities

Prevention

To help prevent heatstroke, the following prevention measures can be used: [5,8]


  1. Take plenty of liquids during outdoor activities, exercise, or sunbathing in summers. The preferred liquids are water and sports drinks.

  2. Take cool showers or baths to cool down your body on hot days.

  3. Wear loose and light-coloured clothing.

  4. Sprinkle water over clothes or skin.

  5. Do not get exposure to the sun between 11 am and 3 pm.

  6. Do not drink alcohol and caffeine-containing fluids, such as tea and coffee. These can cause dehydration.

  7. Avoid vigorous exercise. Schedule sports and exercise during cooler times of the day. Take breaks in shaded or cool areas.

  8. Keep an eye on the elderly, children and people having long-term health conditions like heart problems and diabetes because they are more prone to heatstroke than others.

  9. Keep your house cool, close windows during the daytime in hot summer, shut curtains, and use air-conditioning.

  10. Don not leave your children inside vehicles alone.

  11. Be sure for your child’s protection from the hot sun. Put a hat and wear sunglasses and use an umbrella.

  12. Use sunscreens having a minimum SPF of 15.

  13. Student athletes require frequent breaks for sports drinks and water. An athlete should take about 1 cup of fluid (approximately 300 mL) every 15 minutes while exercising.

  14. Spend time as much as possible indoors on very humid and hot days.

  15. It is important to follow all of the above methods during hot summers to prevent heatstroke. These simple care practices help you to stay dehydrated and keep your body cool.

Diagnosis

If you feel you are having a heatstroke, consult your doctor immediately. Based on the symptoms, your doctor will diagnose heatstroke, but run tests to confirm the diagnosis. Firstly, the diagnosis of heatstroke is based on the triad of high body temperature (greater than 40oC), neurologic abnormalities, and recent hot weather exposure.[3,4]


  1. A blood test is used to check your potassium or sodium levels that help to determine if you are facing dehydration.

  2. A urine sample may be taken. Dark yellow urine may be a signal of dehydration. But do not panic on seeing the yellow coloured urine, some medications also cause yellow coloured urine.

  3. Muscle functioning tests can also be performed.

  4. Your doctor may run tests to check your kidney’s function.

  5. X-rays and other imaging tests may be used to see if there is any internal organ damage.

Treatment

If someone has signs of heatstroke, it is important to take immediate action. Treatment is very important for the person as heatstroke may cause organ failure or even death. There are some first-aid measures that can be taken while waiting for primary help to arrive, including the following:[9,10]


  1. Find a cool place and sit or lie there as soon as possible. Take a cool shower, find a shady spot, or sit in an air-conditioned room. A washcloth wetted with cold water should be placed on the back of the neck or on the forehead.

  2. Take small sips of sports drinks with electrolytes or cold water. Drink water for around an hour, but do not drink too quickly. Avoid caffeinated drinks and alcohol.

  3. Intravenous fluids are sometimes necessary to compensate for the loss of fluid or electrolytes from the body due to dehydration.

  4. Stop doing physical activity. Give rest to your body by sitting or lying.

  5. If symptoms do not improve after an hour of taking fluids and rest, call your physician.

  6. Apply ice to the armpits and groin.

  7. Remove clothing and apply cool water gently to the skin and then fan to stimulate sweating.

Prognosis And Complications

Prognosis

Patients with heatstroke have a high mortality rate, and it depends on many factors. The death rate due to exertional heatstroke is lower (3-5%) than to classic heatstroke (10-65%). The increased death rate is likely due to the presence of prior illnesses and older age. If rapid cooling is successful immediately, there is a zero death rate for patients with exertional heatstroke.

Complications

A patient having heatstroke becomes dehydrated, and sweating does not take place that is necessary to regulate the body temperature. Due to dehydration, the blood becomes concentrated, and organ functioning gets impaired. This can lead to tissue damage in organs, and consequently, multi-organ failure occurs. Below are the complications that are resulted due to heatstroke:


  1. Acute respiratory distress syndrome in which oxygen level in the blood becomes very low)

  2. Hepatic injury or liver injury

  3. Disseminated intravascular coagulation (abnormality in blood clotting in the blood vessels throughout the body)

  4. Acute kidney injury

  5. Hypoglycaemia (low sugar level)

  6. Rhabdomyolysis (breakdown of muscle tissues and discharging of a destructive protein into the bloodstream)

  7. Seizures


Many patients continue to have multi-organ dysfunction and body temperature disturbances even after normalization of temperature with cooling. Even reversible complications due to heatstroke can take more than 7 weeks to resolve.[6,11]

References

Yan YE. Med Hypotheses.2006;67(3):609-17.


  1. Beware of Heat Stroke. Centre for Health Protection. Available at: https://www.chp.gov.hk/en/static/90064.html. Last Updated: 21 June 2021.

  2. Heat-Related Illnesses. Chemical Hazards Emergency Medical Management. Available at: https://chemm.nlm.nih.gov/heatstress.htm. Last Updated: 8 March 2021.

  3. Dan L. Longo. N Engl J Med 2019; 380:2449-2459.

  4. Heatstroke. Health Direct. Available at: https://www.healthdirect.gov.au/heatstroke. Last Accessed: 23 July 2021.

  5. Heat stress – preventing heatstroke. Better Health. Available at: https://www.betterhealth.vic.gov.au/health/HealthyLiving/heat-stress-preventing-heatstroke. Last Accessed: 23 July 2021.

  6. HEAT STROKE RISK FACTORS. UNIVERSITY OF CONNECTICUT. https://ksi.uconn.edu/emergency-conditions/heat-illnesses/exertional-heat-stroke/heat-stroke-risk-factors/. Last Updates: 5 August 2019.

  7. Heat-Related Illnesses in Children and Teens. University of Rochester Medical Center. Available at: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P01611. Last Accessed: 23 July 2021.

  8. Heat Exhaustion. Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/21480-heat-exhaustion#management-and-treatment. Last Accessed: 23 July 2021.

  9. Dehydration and Heatstroke. Johns Hopkins Medicines. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/dehydration-and-heat-stroke. Last Accessed: 23 July 2021.

  10. Morris A. Treasure Island (FL): StatPearls Publishing; 2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537135/.

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