Heat Related Illness

Chris Reed MPT, OCS, ATC

Heat Related Illnesses by Chris Reed MPT, OCS, ATC
I thought this month we would cover a topic that is not really Physical Therapy related, but is very important to consider during the summer months. With the temperatures rising, it is important to monitor your tolerance of the heat. The three types of heat related illnesses will be discussed along with the signs and symptoms, treatment, and ways to avoid each of them.

Physiology:
To dissipate heat and maintain a stable core temperature the body uses one of four mechanisms: conduction, convection, radiation, and evaporation. Conduction is when the body comes in direct contact with a cooler object, such as the water in a swimming pool. Convection occurs when cooler air passes over the body, such as the wind blowing by you while you ride a bicycle. Radiation occurs when the body releases heat into its surrounding environment. The most effective method however is evaporation and occurs when one perspires while exercising or performing strenuous activities. If the body is unable to utilize one of these systems to cool itself, such as the inability to utilize evaporative cooling in hot, humid weather, then the ability to control core temperature is hampered and the risk of suffering from a heat related illness increases.

Heat Cramps:
Heat cramps are the least serious of heat related illnesses. They are typically painful, intense muscle spasm the last for a prolonged period of time. Typically the calves, arms, back, and abdomen are affected. The main cause is inadequate fluid intake during strenuous activity in the heat. Treatment for heat cramps consists of rest, drinking clear fluids or sports drinks, gentle stretching, and gentle massage to the affected muscles. If the cramps do not resolve within an hour, it is recommended you see your doctor.

Heat Exhaustion:
The most common form of heat related illness is heat exhaustion. This is characterized by an increase in core temperature to between 98.6 oF and 104oF. Common symptoms include dizziness, thirst, weakness, headache, malaise, nausea, heavy sweating, ashen appearance, rapid and/or weak heartbeat, low blood pressure, cool and/or moist skin, and a low-grade fever. Excessive sweating can cause one to lose too much salt and become severely dehydrated. The most important thing to do if heat exhaustion is suspected is to continuously monitor their status. Move them into a cooler environment (ie. Shade or air conditioning), elevate their feet, loosen or remove clothing, and have them drink a cool sports drink to replace fluids and electrolytes. Someone who has suffered from heat exhaustion should remain in a cool environment and avoid strenuous activity for several days.
Heat Stroke:
Heat stroke is the most severe form of heat related illnesses. It develops when the body’s ability to sweat and control core temperature is lost completely. Those at risk include someone performing strenuous activities in the heat with inadequate fluid intake, the elderly, the obese, those under the influence of alcohol, and those with cardiovascular disease. Common symptoms include disorientation or unconsciousness; flushed, hot, dry skin; dizziness; hyperventilation; rapid heartbeat; and a core temperature above 105oF. Heat stroke should be considered a medical emergency and 911 should be contacted immediately. While awaiting medical personnel you should move the person into a cooler environment (ie. Shade or air conditioning), spray cool water onto the person while fanning them, or providing cool liquids if tolerated. Following medical treatment, one should follow the doctors recommendations fro avoiding strenuous activity in the heat.

Prevention:
To prevent the occurrence of a heat related illness, the following pieces of advice should be followed. Acclimatize yourself to the heat and humidity over a 2-3 day period prior to partaking in strenuous activities in the heat. Be sure to drink plenty of fluids with electrolytes while working or exercising in the heat. Avoid exercising or working during the hottest hours of the day. Be sure to take a break in a shaded or air conditioned area at least every hour.

References:
1. Heat Cramps: First Aid. Available from URL: http://www.mayoclinic.com
/health/first-aid-heat-cramps/FA00021 (Accessed July 2007).
2. Heat Exhaustion and Stroke. Available from URL: http://www.emedicinehealth.com/heat_
exhaustion_and_heat_stroke/article_em.htm (Accessed July 2007).
3. Heat Exhaustion: First Aid. Available from URL: http://www.mayoclinic.com/health/first-aid
-heat-exhaustion/FA00020 (Accessed July 2007).
4. Management of Heatstroke. Available from URL: http://www.aafp.org/afp/20050601/2133.html (Accessed July 2007).
5. Heat Stroke: First Aid. Available from URL: http://www.mayoclinic.com/
health/first-aid-heatstroke/FA00019 (Accessed July 2007).