What are the risk factors for hyperthermia?
Sensitivity to heat can increase a person’s risk of heat-related illness or hyperthermia. The most common risk factors for hyperthermia is exposure to high heat (such as hot temperatures or being confined in a hot space without air flow, like a car). Exposure to hot temperatures can be temporary (i.e. a day) or last several days without being exposed to any means of cooling down (i.e. changes in climatic temperature or cooling mechanisms such as a fan or air-conditioner).
A high heat index refers to exposure to hot temperatures and humidity levels. Low humidity levels or very dry environments cause sweat to evaporate more easily and quickly. As a result, the body is unable to use this mechanism to cool down.
When exposed to sudden temperature changes, exposure that adjusts from cold to warm / hot in a short space of time can place strain on temperature regulation. The body may have difficulty in adjusting to dramatic climate changes and place a person at risk of hyperthermia. An example would be going on a vacation to a location with a much hotter climate than the area in which you generally live. Having a very bad sunburn can also cause heat-related illness.
Normally, a constant body temperature can be maintained by balancing heat gain with heat loss. When the body is exposed to excess heat or it is unable to lose heat effectively enough, a person's condition can worsen and heatstroke occurs. As body temperature rises and heat gain exceeds heat loss capability, risk for heatstroke therefore increases.
Some other risk factors include:
- Hot environments and occupation: Some occupations require long hours exposed to high heat environments or locations. Construction or farm workers are often outside for long hours and can be at increased risk of heat-related illness. Firefighters are another group who are exposed to high heat on the job in poorly air-conditioned spaces, while having to wear heavy, protective clothing.
- Hot environments and strenuous exercise: Over-exertion during exercise activity (such as intense gym workouts or running) and sports participation (football or soccer, tennis or basketball) in a hot climate can easily place a person at risk of hyperthermia.
- Medical conditions and medications: Certain health conditions and their treatment medications can affect the body’s ability to cool down effectively. Conditions such as high blood pressure (hypertension) that is being managed with a low-sodium diet can put a person at higher risk of hyperthermia in relevant conditions. Diuretics which are also used for the treatment of heart and blood pressure problems can also interfere with the body’s internal thermostat or cause difficulties in staying sufficiently hydrated. Some sedatives and tranquilisers, as well as beta-blockers and antihistamines can also have the same effect. Any condition that makes a person vulnerable to dehydration can lead to a higher risk for hyperthermia. Those who are overweight or obese experience more heat retention due to excess weight. This can make it more difficult for the body to regulate internal temperature and cool down effectively when it becomes necessary. Those who are underweight can also experience difficulties with temperature regulation. Poor circulation problems (or blood vessel disorders), mental disorders, such as dementia or Alzheimer’s disease, inadequately functioning sweat glands, and kidney, lung or heat disease, are other conditions that can make a person more susceptible to heat-related illnesses.
- The very young and elderly: Seniors (over 65) and children (especially those under the age of 4) are often more at increased risk of heat-related illness, as they typically tend to less aware of temperature changes and their bodies generally don’t regulate as well. Children often engage in strenuous activity outside, and in hot climates are at risk if they do not rest, stay hydrated and cool off appropriately. Children also have a higher metabolic rate and typically do not cool down as effectively through perspiration as adults. Infants have an immature thermoregulatory system. Seniors can often be non-responsive (i.e. not reacting in time and moving to a cooler spot or activating a fan) to temperature changes (this can sometimes happen in those of any age with a mental illness as well). Senior bodies are less likely to compensate for heat-related illness (i.e. adjust as effectively as younger adults). Pre-existing conditions (and associated medications) can also cause difficulties in regulating internal body temperature, mostly due to dehydration vulnerability. Coupled with extremely hot weather conditions, children and the elderly are often at higher risk.