Heat stroke is common during the hot season; what are the causes, symptoms and treatment?

Key takeaways

• A heat stroke is a medical emergency that occurs when there is an extreme increase in body temperature and can lead to death if not managed promptly. 
• High body temperature, hot and dry skin, confusion, seizures, nausea, and headaches are signs and symptoms of heatstroke. 
• First-aid treatment for people with heat stroke involves keeping them cool by giving them cold baths and keeping them in a cool environment.
• Heat stroke can be prevented by staying hydrated, using air conditioners, and avoiding rigorous activities in hot weather or if physically unfit.

Sweating is one of the body's mechanisms for maintaining a normal body temperature of 36.1°C to 37.2°C. When the environment is hot or cold, the body regulates its temperature accordingly. 

However, if this regulation fails to occur for any reason and the environmental temperature is high, the body will also become very hot, exceeding the normal body temperature. This could lead to different heat-related illnesses, which could be as mild as a heat rash or as severe as a heat stroke.

What is heat stroke?

Heatstroke is a medical emergency characterized by an extreme increase in body temperature, usually greater than 40°C, associated with a malfunctioning central nervous system and hot, dry skin. It is on the severe end of heat-related illnesses.

Types of heat stroke

There are two types of heat stroke, and they are:

1. Exertional heat stroke

Exertional heatstroke usually occurs in some individuals after they exert themselves through strenuous exercise during the hot weather.

The exact reason why heat stroke occurs during physical activity in some individuals is unclear. However, it is believed to be due to an impairment in the body’s thermoregulation system and an overload of the heart and blood vessels, resulting in a severe, abnormally high body temperature (hyperthermia). 

About 3–5% of people die from exertional heatstroke compared to classic heat stroke, which has a much higher death rate. Athletes, soldiers, and labourers are at increased risk of this type of heat stroke.

2. Classical heat stroke

Classical heat stroke usually affects the elderly and people with chronic medical conditions like diabetes, obesity, renal disease, hypertension, heart disease, alcoholism, and dementia. About 10–65% of people with classical heatstroke die from it.

Causes of heat stroke

Common causes of heat stroke include:

• High temperature: When the body temperature is as high as 40°C, one can have a heat stroke. This could be due to the body's inability to lose heat as quickly as it gains it, which means its thermoregulation is dysfunctional. It could also occur if one is in a very hot environment, during a heat wave, or in very hot weather.
• Strenuous activities: Heat stroke can occur when a person performs strenuous activities beyond their abilities. Physical activities greater than what a person’s body can handle at a time can increase the person’s risk of having a heat stroke.
• Ageing: The body’s ability to regulate its internal temperature reduces as a person ages. Their sweat glands begin to function less properly, which means they sweat less and are unable to effectively get rid of heat. This increases their risk of developing heat stroke.
• Chronic illnesses: In chronic illnesses like diabetes, the body's ability to fight diseases is reduced. This affects the body's ability to perform other functions, including thermoregulatory functions, which can lead to heat stroke. 

Signs and symptoms of heat stroke

The following are the signs and symptoms of heat stroke:

• High body temperature: This is when the body temperature is greater than 39°C. This can be checked using a thermometer. 
• Shortness of breath: This occurs when someone breathes very fast and loud but doesn't seem to get enough air.
• Rapid pulse rate: This occurs when the heart beats very fast.
• Headache: This is usually a throbbing kind of headache. 
• Seizure: When someone suddenly becomes abnormally rigid or starts making sudden jerking movements, it may be a symptom of heatstroke. 
• Dizziness: You may feel lightheaded or very unbalanced. 
• Nausea: A feeling of throwing up often accompanies a heat stroke.
• Altered mental state: Being disoriented, confused, saying unintelligible things, and slurring speech are also common symptoms of heatstroke. 
• Hot and dry skin: Heatstroke can also present as extremely hot skin without sweating. 
• Loss of consciousness: In this state, a person with heatstroke will be unable to respond to touch and sound. They will also be unable to move their bodies.

Risk factors: Who is more likely to develop heat stroke?

Anyone can develop heatstroke, but some people may be more prone to it. People at a higher risk of experiencing heatstroke include:

• Children under 4 years old and older adults 65 years and above
• People who are physically unfit and yet do strenuous exercises
• People who are soldiers, firefighters, athletes, and construction workers
• People who experience extremely hot weather 
• People who abuse drugs and alcohol
• People who use antihypertensive drugs like beta blockers and diuretics
• People with a viral or bacterial infection
• People who are susceptible to peer pressure
• People with health conditions like diabetes and heart problems

Complications of heat stroke

Heat stroke, if not managed properly and quickly, can cause multiple organ damage, permanent disability, and a persistent risk of death.

Organ damage caused by a heat stroke includes:

• Acute lung injury: Acute respiratory distress syndrome (ARDS), a type of acute lung injury, can occur in people with heatstroke. In ARDS, there's reduced oxygen in the lungs, and the lungs don't expand as usual when one breathes in. ARDS has a high death rate.
• Skeletal injury: Rhabdomyolysis is a form of skeletal injury in which the skeletal muscles rapidly break down and die, releasing their contents into the blood. This causes muscle weakness and pain. 
• Acute kidney injury (AKI): A study in China shows that 44% of patients with exertional heat stroke develop acute kidney injury (AKI), and 27% of patients with AKI die within 90 days.
• Liver injury: In people with heatstroke, there may be reduced blood flow to the liver, causing parts of the liver to die (liver necrosis). This reduces the function of the liver. 
• Cardiovascular injury: Patients with heat stroke have a higher risk of having myocardial infarction (heart attack), ischaemic heart disease, and stroke. These complications may occur years after a heat stroke has occurred. 
• Brain injury: This is the first organ dysfunction that occurs following a heat stroke. Patients can have an altered mental status and go into a coma. There can also be long-term complications, like a reduced ability to move the body and reduced cognitive abilities. 
• Intestinal injury: Different parts of the intestine may become injured and leaky such that its contents, which include certain toxins, can get into the blood.

First-aid treatment for heat stroke

The first thing to do when someone experiences a heatstroke is to call for help. Dial 911 or your local helpline, and then keep the heat stroke patient cool by doing the following:

• Move them to a place with a cooler temperature, like an air-conditioned room or a shaded, cool area.
• Remove their clothes.
• Put them in cold or ice water in a bathtub, or give them a cold shower. Be careful so water doesn't get into their mouth or nose.
• Give them a sponge bath using cool water.
• If cold water is unavailable, use room-temperature water.
• Place wet clothes on their body, especially their head, neck, armpits, and groin.
• Keep monitoring their body temperature. 

Tips for preventing heat stroke

It's more effective and easier to prevent heat stroke than to treat it. Doing the following can help prevent heat stroke:

• Stay in well-ventilated houses.
• Stay in an air-conditioned room.
• If air conditioners are unavailable, use a fan.
• Take frequent cold baths during hot weather.
• If you are physically unfit, do low-intensity exercises.
• Drink cold water in between exercises and rigorous activities. 
• Reduce physical exertion.
• Check on the elderly in your family or around you, especially in extremely hot weather.
• Don't wear excessive clothing when the weather is hot.
• Wear loose-fitting and light-colored clothing in hot weather.
• Stay hydrated by drinking enough water.
• Don't drink too much alcohol.
• Don't do strenuous activities during hot weather.

Seek immediate medical care for heat stroke

Heat stroke is a life-threatening condition and a medical emergency. If someone experiences the signs and symptoms of heat stroke, do the following:

• Call for help.
• Give them first aid for heat stroke. 
• Rush them to the hospital if help hasn't arrived for a proper diagnosis and treatment.