Heat Stroke

Heat Stroke

Heat stroke is a form of hyperthermia in which the body temperature is elevated dramatically.


Heat stroke is a medical emergency and can be fatal if not promptly and properly treated.


Cooling the victim is a critical step in the treatment of heat stroke.


The most important measures to prevent heat strokes are to avoid becoming dehydrated and to avoid vigorous physical activities in hot and humid weather.


Infants, the elderly, athletes, and outdoor workers are the groups at greatest risk for heat stroke.


What is, and who is at risk for heat stroke?


Heat stroke is a form of hyperthermia, an abnormally elevated body temperature with accompanying physical symptoms including changes in the nervous system function. Unlike heat cramps and heat exhaustion, two other forms of hyperthermia that are less severe, heat stroke is a true medical emergency that is often fatal if not properly and promptly treated. Heat stroke is also sometimes referred to as heatstroke or sun stroke. Severe hyperthermia is defined as a body temperature of 104 F (40 C) or higher.


The body normally generates heat as a result of metabolism, and is usually able to dissipate the heat by radiation of heat through the skin or by evaporation of sweat. However, in extreme heat, high humidity, or vigorous physical exertion under the sun, the body may not be able to dissipate the heat and the body temperature rises, sometimes up to 106 F (41.1 C) or higher. Another cause of heat stroke is dehydration. A dehydrated person may not be able to sweat fast enough to dissipate heat, which causes the body temperature to rise.


Those most susceptible (at risk) individuals to heart strokes include:


  • infants, 
  • the elderly (often with associated heart diseases, lung diseases, kidney diseases, or who are taking medications that make them vulnerable to dehydration and heat strokes), 
  • athletes,
  • individuals who work outside and physically exert themselves under the sun.


Symptoms of heat stroke can sometimes mimic those of heart attack or other conditions. Sometimes a person experiences symptoms of heat exhaustion before progressing to heat strokes.


Signs and symptoms of heat exhaustion include:



However, some individuals can develop symptoms of heat stroke suddenly and rapidly without warning.


Different people may have different symptoms and signs of heatstroke.


Common symptoms and signs of heat stroke include:


  • high body temperature,
  • the absence of sweating, with hot red or flushed dry skin, 
  • rapid pulse, 
  • difficulty breathing, 
  • strange behavior,
  • hallucinations, 
  • confusion, 
  • agitation, 
  • disorientation, 
  • seizure,
  • coma.


Summer temperatures in the United States can climb above 100 degrees Fahrenheit (38 de-grees Celsius), making heat stroke a big problem. Heat stroke can be fatal in many cases because it happens so quickly - there is not much time to react.


Let's say that it really is 100 degrees F outside. The human body wants to stay at 98.6 degrees F. The only way to stay at 98.6 is to sweat. By putting moisture on the skin and letting it evaporate, your body can cool itself very effectively and keep its temperature in the proper range.


Sweat works really well as long as there is plenty of water in your body - it takes water to manufacture sweat. If you run out of water, sweat stops and your body rapidly overheats.


It turns out that it is extremely easy to run out of water - your body can produce 0.5 gallons (2 liters) of sweat every hour in a hot environment. Unless you are drinking water at the same rate, you will dehydrate and then stop sweating.


Your internal thirst meter often is not sensitive enough when you need that much water (and it has been said that by the time you feel thirsty, you're already dehydrated), so you have to keep drinking regardless of how thirsty you feel.


The other thing that can lead to heat stroke is very high humidity, which keeps sweat from evaporating.

In either case - be it the lack of sweat or the inability to evaporate it - the core body temperature can rise very quickly if it is hot outside. Once the core gets to 106 degrees F, it is a serious problem.


Symptoms include red, hot, dry skin (the body dilates skin blood vessels to try to release heat, making the skin red, and the dryness comes from lack of sweat), rapid heart rate, dizziness and confusion. The dizziness and confusion come from the high body temperature, which affects the brain.


The reason the temperature rises so high and so fast is because the interior of a car is an excellent solar oven that uses the greenhouse effect to trap heat. Sunlight heats the sheet metal of the car, and it streams in through the windows to heat the interior.


It turns out that glass is completely transparent to visible light but opaque to infrared light - and infrared light is the heat that is trying to radiate back out of the interior.


So the temperature rises rapidly, to the point where you often cannot touch the steering wheel without getting singed. Leaving the window cracked is not going to help - it is never safe to leave a child or pet in a parked car for any length of time.


The only solution for heat stroke is to cool the person down. You can:


  • Try to get the person to drink water if the person is conscious.
  • Soak the person's entire body in cool water.
  • Sponge cool water onto the person's body.
  • Apply ice packs to the head, neck, armpits and groin.
  • If not treated, heat stroke can be fatal in less than an hour.


Home care is appropriate for mild forms of heat exhaustion. Heat stroke is a medical emergency, and an ambulance should be called immediately.

For mild cases of heat exhaustion

  • Rest in a cool, shaded area. 
  • Give cool fluids such as water or sports drinks for dehydration (that will replace the salt that has been lost).

Salty snacks are appropriate as tolerated. 

  • Loosen or remove clothing. 
  • Apply cool water to skin. 
  • Do not use an alcohol rub. 
  • Do not give any beverages containing alcohol or caffeine.
Heat stroke (do not attempt to treat a case of heat stroke at home, but you can help while waiting for medical assistance to arrive.) 
  • Call 911 immediately.
  • Move the person to a cooler environment, or place him or her in a cool bath of water (as long as the person is conscious and can be attended continuously). 
  • Alternatively, moisten the skin with lukewarm water and use a fan to blow cool air across the skin. 
  • Give cool beverages by mouth only if the person has a normal mental state and can tolerate it.

Medical Treatment

The treatment is directed at cooling the patient in a controlled fashion while making sure that the patient stays hydrated and that blood flow is normal.

Treatment of heat exhaustion 

  • Because heat exhaustion generally develops gradually, a person will often be dehydrated. Usually they may be given something to drink, and a cool sport beverage (with 6% or less glucose) should be used. IV fluid may be used if the person does not tolerate oral replacement (if he or she cannot keep anything down). 
  • The patient should stay in a cool environment and avoid strenuous activity for several days.

Treatment of heat stroke 


  • Treatment is aimed at reducing the patient's core temperature to normal as quickly as possible. 
  • The doctor may use immersion, evaporative, or invasive cooling techniques. 
  • In the evaporative technique, cold or ice packs may be placed in the armpits or groin. The skin is kept moist with cool fluid, and fans are directed to blow across the body.
  • An IV will be started and fluids are given rapidly. 
  • The patient's urine output will be monitored. 
  • Treatment will continue until the patient's body core temperature is 101.3-102.2 F (38.5-39 C) and then stopped to keep from making the patient too cold. 
  • The patient most likely will be admitted to the hospital for further blood tests and observation.
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