Heat stroke - What is heat stroke?

By Dr Ananya Mandal, MD

Heat stroke and heat exhaustion are heat related health conditions that may be serious and life threatening if not treated adequately and promptly. These are common in very hot and dry weathers and are mainly seen in the tropical countries.

Causes of heat stroke

Heat related conditions are not a result of a hot environment alone. The three factors that determine causation of these conditions include:

  • high environmental temperature
  • high humidity
  • increased physical exertion

Heat related health conditions may begin as heat cramps and proceed to heat exhaustion and finally heat stroke. (1-4)

Incidence of heat stroke

The actual incidence of heat stroke is not known because this illness is not well reported and diagnosed.

The incidence of heat related health conditions is relatively low in United Kingdom. There are around 40 cases of heat-related deaths per million population per year.

The risk rises in hotter countries, for example, it is high among periods of time such as Hajj, the annual Muslim pilgrimage in Saudi Arabia. In Saudi Arabia, the incidence of heat stroke varies seasonally, from 22 to 250 cases per 100,000 population.

Data from the Centers for Disease Control and Prevention (CDC) show that from 1979 to 1997, 7,000 deaths in the United States were attributable to excessive heat. Overall incidence studies in the US shows that the incidence of heat stroke is between 17.6 to 26.5 cases per 100,000 population.

The deaths due to heat are on the rise with global warming and the rise of frequency and intensity of heat waves worldwide.

When does heat exhaustion occur?

Heat exhaustion occurs when the body’s temperature within, or the core temperature, rises above the normal 37°C (98.6°F) to anything up to 40°C (104°F). The salts and water in the body at this temperature begins to fall leading to a general feeling of illness, faintness and heavy sweating.

This stage needs to be quickly treated by taking the person to a cool place, offering water to drink and removing excess clothing. Within 30 to 40 minutes the patient starts to feel better and there are no lasting ill effects of the condition.

What is the difference between heat exhaustion and heat stroke?

If heat exhaustion is left untreated, it could become heatstroke.

Who is at risk of heat stroke?

People who develop heat stroke easier than others include:

  • children below two years
  • very old persons
  • disabled persons,
  • those with heart, kidney or other problems
  • those with diabetes who take regular insulin

In addition, those who have taken too much alcohol are at risk since alcohol causes dehydration.

Persons taking certain drugs and medications, such as antipsychotics and beta-blockers are also at risk.

Complications of heat stroke

Heat stroke may lead to complications like dehydration and may need hospitalization. Heat stroke occurs when the body is unable to cool itself and the temperature continues to rise. As the temperature reaches over 40°C (104°F), the cells inside the body stop working and start to break down. This may lead to organ failure and brain damage and even death.

There may be symptoms such as confusion, shallow and rapid breathing rates and unconsciousness.

Treatment of heat stroke

Heatstroke needs immediate emergency attention. The affected person should be kept as cool as possible, excess clothing should be removed; patient should be cooled further by fanning etc.

In conscious patients cool but not cold water is offered to drink in sips.

Prevention of heat related emergencies

Prevention of heat related emergencies include simple precautions like staying out of the sun, particularly between 11am and 3pm when it is the hottest. Those who need to step out may use a shade or an umbrella, wear a wide brimmed hat and apply sunscreen.

Extreme physical exertion in the heat should be avoided. No one should be left alone in a parked car left in the sun.

During heat waves all are advised to take plenty of fluids while avoiding those that contain caffeine and alcohol and also take cold foods like salads and fruit that are rich in fluids.

Individuals are advised to take regular and if needed frequent showers and sprinkle water over skin and clothing to keep them cool.

Reviewed by April Cashin-Garbutt, BA Hons (Cantab)

Further Reading

Sources

  1. http://www.nhs.uk/conditions/Heat-exhaustion-and-heatstroke/Pages/Introduction.aspx
  2. http://www.patient.co.uk/doctor/Heat-Related-Illness.htm
  3. http://www.ehs.psu.edu/help/info_sheets/OSHA_Heat_Stress_Card_060616.pdf
  4. http://www.med.navy.mil/sites/nhoki/Patients/CommunityHealth/PopHealth/Documents/HeatStroke.pdf
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