Help patients beat the extreme heat

Australia is in the midst of a record-breaking heatwave – with Western Australia, South Australia, Tasmania, Victoria, the ACT and NSW all reaching maximum temperatures of 8-12°C above average.

Parts of South Australia, Victoria and NSW are expected to reach maximum daytime temperatures in the mid-40s.

In a joint statement, the Bureau of Meteorology, New South Wales Health and the New South Wales Rural Fire Service have warned that the heatwave conditions are expected to bring elevated fire risks to NSW a the ACT, as well as pose a danger to people’s health.

People have been advised to avoid strenuous activity, drink plenty of water and ensure the safety of those who are most vulnerable – including older people and children.

Recognising heat-related illness

As previously reported by Australian Pharmacist in an article written by University of Tasmania Professor of Pharmacy Gregory Peterson, heat-related illness is often preceded by heat exhaustion, which is caused by water or salt depletion due to high heat exposure or strenuous physical activity.

Signs include:

• intense thirst;
• weakness;
• nausea and vomiting;
• dizziness, fainting;
• headache;
• muscle cramps; and
• typically normal body temperature. It can be elevated, but if so is usually less than 41°C.

Signs and symptoms of dehydration are almost always present – tachycardia, hypotension and sweating.

Without treatment, heat exhaustion can lead to heat stroke – a medical emergency where the person presents with a core body temperature above 40°C. Signs and symptoms include hot and dry skin, multiple organ dysfunction, and central nervous system abnormalities, such as confusion, delirium, ataxia, convulsions or coma. The key difference between heat stroke and heat exhaustion is the central nervous system dysfunction present only in heat stroke.

Prognosis of a person with heat stroke depends on how early a diagnosis is made, and how promptly cooling measures and fluid and electrolyte resuscitation are started. Otherwise progression to death can occur rapidly. People at risk are those with cardiovascular, respiratory and renal diseases. Risk also increases when patients take medicines that impair thermoregulatory processes, either via the hypothalamus or peripherally. Medicines include diuretics, antipsychotics and drugs with anticholinergic properties such as tricyclic antidepressants.

How pharmacists can help

In a recent interview with Australian Pharmacist, Professor Peterson said that when people present to a pharmacy with any symptoms relating to heat illness or heat stroke, their latest movements should be deciphered.

‘Pharmacists should find out if people have been outdoors in the heat, what they might have been doing outdoors and how long they spent out in the heat. It’s equally important to identify what they have been drinking and eating – whether they have consumed high fluid-content food, have been drinking adequately and what medicines they are taking.’

Professor Peterson said that there are certain medicines, such as antipsychotics and anticholinergics which are often taken by older people, that can impair thermoregulatory processes.

Once heat illness is identified, pharmacists should recommend rapid cooling measures to drop the core body temperature quickly.

‘People should stay within an air-conditioned space coupled with plenty of cold fluids. Towelling with a cold cloth can also help and pharmacists can measure the person’s temperature to determine if it’s above 40°C, indicating heat stroke,’ Professor Peterson said.

Antipyretic medicines, such as aspirin and paracetamol, are not recommended to treat these conditions. Professor Peterson said that these medicines are not effective in treating either heat exhaustion or heat stroke.

Pharmacists should advise people to look out for continued symptoms that could indicate that the condition is progressing to heat stroke – such as ongoing thirst, reduced/concentrated urine output, confusion and dizziness – and explain just how quickly the condition can shift. Rapid treatment should then be sought in the form of intravenous fluids or ice-packing in a hospital environment to keep the temperature down.

He also said that pharmacists should advise people to notify relatives that they are feeling unwell, so should their condition worsen and they experience confusion, a cognisant person will be able to manage their care.

Taking care of older people

Professor Peterson explained that older people are more susceptible to heat-related illness, as their homeostatic mechanisms are not as robust as those in younger adults.

Also, ‘the high number of medicines often consumed by older people contributes to their heat sensitivity. This impairs their ability to cope with heat stress,’ he said.

Fluid intake is not usually high amongst older people, particularly in those with enlarged prostates or urinary incontinence.

Some advice pharmacists can give older people in the heat includes:

• drink small amounts of nonalcoholic fluids before thirst sets in;
• eat cold foods with a high fluid content;
• stay cool by using an air conditioner at home or have access to air-conditioned areas, such as shopping centres;
• stay indoors out of the heat during the hottest part of the day and take extra showers if possible;
• wear lightweight, loose-fitting clothes;
• maintain frequent contact with family, friends or carers.

For further information on the risk of drug-associated heat stroke in the elderly, click here.