Heat/sun stroke: stay cool!

Published in MapleLine Magazine: May 5, 2010

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by Dela Wilkins

Although we live in a moderate climate on southern Vancouver Island, the hot sunny days of summer can put our health at risk. Heat-related illness can be prevented by drinking plenty of water and avoiding strenuous activity in hot weather.

Our bodies are not accustomed to high heat and high humidity, and our body thermostat has difficulty maintaining the core temperature at 37oC. We become uncomfortable, exhausted, feel ill, and in extreme cases, heat stroke can result which cause death when the body cooling mechanism fails and the body core temperature reaches 40-41oC.

While the terms heat stroke and sunstroke are often used interchangeably, sunstroke is a type of heat stroke where the source of heat is the direct sun. Heat stroke and sunstroke are both distinct medical emergencies and can be fatal if not treated promptly. Keep the person cool, in the shade, and apply cool water to the skin while waiting for an ambulance.

Heat stroke is caused by extreme temperatures and can occur indoors, in a variety of work settings, or in the shade outdoors. In a study funded by General Motors of Canada, it was found that the air temperature in a previously air-conditioned small car rose to 50oC within 20 minutes, and to 65.5oC in 40 minutes. In sunstroke the heat source is direct radiation from the sun on exposed skin, or a sparsely covered head. Radiation penetrates the skull, and the head may become overheated. Sunstroke can occur on a sunny day with milder temperatures and kills over 10% of its victims.

Prevention. During extreme heat the most important thing is to keep cool. The very young, the elderly, and those on some medications have more difficulty with regulating body temperature, and need to take extra precautions. The core temperature of infants and small children can increase three to five times faster than that of an adult.

Short Term Effects. After the Chicago heat wave of 1995, American researchers interviewed 58 patients who had been admitted to hospital with symptoms of near-fatal heat stroke. They found that almost a full quarter of the subjects died within the year; most of them within the first three months. All of the
remaining survivors suffered some amount of brain and nervous system impairment. Approximately half were diagnosed with kidney problems and blood clots, while 10% of the group experienced malfunction of the lungs due to inflammation. After taking into account each subject's health conditions before hospitalization, all of these side8effects were judged to be a direct result of heat stroke.

Long Term Effects. One report states that workers who have suffered heat-related illness are often less able to tolerate heat following the event, while others suffer from hypertension, heart muscle damage, and chronic heat exhaustion. Studies at the Chinese University of Hong Kong show that brain damage caused by overheating can have long term effects, depending on which part of the brain was damaged: impaired muscle movement, vision, speech, and the ability to properly regulate body temperature.

Anyone who has suffered with heat stroke or sunstroke should take major precautions to prevent another occurrence. Extremely hot weather is announced by Environment Canada to help people reduce health-related risks. The Humidex is a measure of the combined effect of temperature and humidity and describes how hot it feels. According to the Meteorological Service of Canada, a Humidex of 30 causes "some discomfort", at 40 there is "great discomfort" and above 45 the health risk is considered "dangerous". When the Humidex hits 54, heat stroke becomes likely. The UV Index is a measure of the strength of the sun’s rays. Radiant heat from the sun increases the Humidex by 2-3oC.

When hot sunny weather is forecast, the Vancouver Island Health Authority issues a Public Service Announcement listing the symptoms of heat stroke:
• Hot, red, dry skin
• Rapid pulse
• Rapid, shallow breathing
• Headache
• Confusion, untypical behaviour
• Possible loss of consciousness
• Extremely high core temperature of up to 41oC

The best way to stay safe and healthy this summer is to create your own Keep Cool Plan:
• Drink lots of water – at least one or two cups each hour, more if you are very active. Don’t wait until you are thirsty to replace body fluids.
• Avoid liquids high in sugar or alcohol as they increase the amount of fluid lost by the body. Caffeine will also increase dehydration.
• Some medications may have side effects during extreme heat.
• People who are overweight have a greater body mass to cool.
• Some chronic diseases such as diabetes, heart failure and cancer change the way the body gets rid of heat.
• Take a cool bath or shower, or place a damp towel around your neck and on your forearms.
• Seek the shade or make your own. Use an umbrella or wide-brimmed hat outdoors.
• Limit physical activity especially during the hottest part of the day.
• Never leave children or pets in a parked car even on mild days.
• Keep your house cool. Close curtains in daytime, open windows if it is cooler outside at night.
• Fans have little benefit when the air temperature exceeds the skin temperature, and may even heat up the body.
• Offer to check up on and help your neighbours who are housebound.

Dela Wilkins is a nurse and life care coach.

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This article was published on pages 24-25 in the print edition of MapleLine Magazine (Summer 2010 issue - May-July 2010).