Y Bont: 2006: July/August: Health

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2006 July/August

HEALTH MATTERS

Heatstroke
Introduction

Heatstroke is a serious condition that occurs when the body is unable to control its temperature due to excessive heat. Body temperature rises sharply, causing hyperthermia (body temperature greatly above normal) and dehydration (loss of water from the body).

In normal circumstances, the body controls temperature by disposing of heat through the skin, mainly by sweating. The normal temperature is 36-36·8˚C (96·8-98·24˚F). However, very high temperatures of over 40˚C (104˚F) can cause the body’s internal thermometer to fail so that heat is not disposed of adequately and the body cannot cool down in the usual way.

Symptoms

Heat exhaustion is usually one of the first signs that you are at higher risk of developing heatstroke. Symptoms to be aware of are:

• headaches • dizziness • nausea and vomiting • muscle weakness or cramps,
• stomach cramps • pale skin • weak pulse, and • high temperature.

If you experience these symptoms after exposure to hot conditions, physical exertion or burns, move to a cool area and re-hydrate by drinking plenty of fluids. Re-hydration solution (available from your local pharmacy) and some sports drinks are useful for rapid re-hydration, although in most cases, plain water is fine.

You should remove any excess clothing and may consider cooling yourself down with lukewarm water (sponging or showering your body).

Left untreated, these symptoms can develop into heatstroke. Heatstroke can also occur suddenly and with little warning. The symptoms of heatstroke include:

• symptoms as for heat exhaustion,
• confusion and disorientation,
• convulsions (uncontrollable muscle twitching),
• unconsciousness,
• racing, thumping pulse,
• flushed, hot and dry skin, and
• very sudden rise in temperature.

Causes

Heatstroke occurs when the temperature of the body rises sharply. This may happen because of excessively high outside temperatures, physical exertion, extensive burns, and severe sunburn or because of an undiagnosed medical condition such as an overactive thyroid gland.

The heat can affect anyone, but some people are at greater risk of serious harm. These include:

Older people;
Babies and young children;
People with a serious chronic condition, particularly breathing or heart problems;
People with mobility problems;
People who are physically active, like manual workers and sportsmen and women.
Certain medications can also make you more susceptible to heat exhaustion. These include:
• Diuretics - these drugs increase the production of urine, so they can add to dehydration;
• Lithium, anti-epileptics, statins - these may not work properly if you get dehydrated;
• Beta-blockers - these drugs help reduce blood pressure but they also interfere with the body’s processes of thermoregulation (how it copes with getting too hot), such as sweating.

Contact your doctor, a pharmacist or NHS Direct if you are worried about your health during a heatwave, especially if you are taking medication or have any unusual symptoms.

Diagnosis

A body temperature of 39·5˚C or higher in conjunction with the described symptoms is heatstroke. If the patient’s temperature is above 41˚C, they are in a critical condition and require emergency medical attention.

On arrival at hospital, the doctor should be told about:

• the exposure to high temperatures,
• whether the person has taken part in physical exercise,
• if there is a pre-existing medical condition, and
• previous attempts to cool the person down.

Temperature and pulse will be closely monitored, and the doctor will also look for signs of neurological illness such as confusion, irrational behaviour, seeing things that aren’t really there (hallucinations) and fits (seizures).

Some tests (including blood tests, x-rays, or imaging scans) may be performed to check the extent of damage from heatstroke, and to determine if other disorders are present.

Treatment
Treatment for heatstroke, or suspected heatstroke:

• Get professional medical help as quickly as possible.
• Move to a cool area as quickly as possible.
• Increase ventilation by opening windows or using a fan.
• Give them water to drink if possible, but do not give medication such as aspirin or paracetamol.
• Shower the skin with cool, but not cold, water (15 to 18°C).
• Alternatively, cover the body with cool, damp towels or sheets, or immerse in cool water.
• Gently massage the skin to encourage circulation.
• If convulsions start, move nearby objects out of the way to prevent injury. Do not use force or put anything in the mouth.
• If the patient is unconscious and vomiting, move them into the recovery position by turning them on their side and making sure their airways are clear.

Once in hospital, the patient may be given oxygen through a mask, intravenous fluids through a drip and medication to regulate their temperature and stop convulsions.

Complications
Complications include:

• Hypoglycaemia (drop in sugar levels),
• Dehydration (drop in fluid and salt levels),
• Organ failure (kidney, liver or heart), and
• Brain damage.

Heatstroke can be fatal if left untreated. It is therefore important to get medical attention as soon as possible.

Prevention

Most people living in the UK are unused to high temperatures and our bodies do not cope well with intense heat. When travelling to hotter climates it is important to let your body adjust and reducing the risk of dehydration by gradual acclimatising to the temperature. You can do this by avoiding long periods of time in the sun, drinking plenty of salty fluids, and avoiding alcohol and drinks containing caffeine such as tea, coffee and cola.

You should also avoid strenuous physical activity if possible and take care to cool yourself down if you feel you may be overheating. This is best done by wearing loose fitting, light clothing and a wide-brimmed hat, spending time in the shade or in an air-conditioned environment, and showering or taking regular dips in the sea or swimming pool. Always use a wide-spectrum high sun protection factor (SPF) 15+ sunscreen.

It is important to note that you can also get sunstroke in the UK, particularly if there is a heatwave. Listen to weather forecasts so that you can plan to stay out of the heat, especially in the hottest part of the day (11 a.m. - 3 p.m.). In very hot weather, close the curtains in rooms that get a lot of sun, and stay inside in the middle of the day, in the coolest rooms in your house.