Hypothermia danger to elderly

Elderly patients are at risk from hypothermia if their home is inadequately heated. By Dr Linda Miller

Edith was an 80-year-old woman with heart failure, who was relatively immobile.

She was generally chair bound but was able to walk to the bathroom with her walking frame. Although she did not have any family living nearby, she managed at home with a supportive package of carers calling three times a day.

However, one morning in November her carers found her unwell.

When Edith’s GP visited, she found her drowsy and sitting slumped in her chair, her breakfast untouched on the table beside her. She was pale, bradycardic and hypotensive and her hands were cold to the touch, although the skin on her abdomen felt clammy.

On examination her chest was clear although respiration was slow and shallow.

Suspecting a UTI, MI or cerebrovascular event, the GP arranged urgent admission to hospital.

At A&E Edith’s rectal temperature was 33°C. Her blood sugar was normal, but blood chemistry showed metabolic acidosis. An ECG showed J waves — rounded waves after the QRS complex, pathognomonic of hypothermia. Blood tests also revealed mild hypothyroidism.

Aetiology

Hypothermia is an obvious risk for those exposed to extreme temperatures; arctic explorers, those who have fallen into cold water or homeless people.

However, it can also be a hazard for those who are relatively immobile, particularly the frail elderly within their homes.

The elderly may have a reduced perception of the cold (particularly those with dementia or acute confusion), impaired homeostatic mechanisms, and may lack an insulating layer of fat.

Alcohol, antidepressant drugs, sedatives and diuretics and intercurrent illness increase the risk of hypothermia as do diseases such as pneumonia, heart failure and MI.

Autonomic neuropathy due to diabetes or Parkinson’s disease can also be a factor.

Poverty and heating

Many elderly in the UK live in poverty and limit their use of heating because of the expense. The charity Help The Aged report that there were 28,700 cold-related deaths among the elderly in England and Wales in 2005.

Many are not aware of government schemes for help with heating, and 40 per cent of elderly people keep bedroom windows open at night, believing it is healthy, even in cold weather.

Symptoms and signs

Hypothermia is defined as a core temperature below 35°C. It is often lethal when the temperature is less than 32°C.

The patient feels cold to the touch but flexures in the axillae, groin and abdomen feel clammy. Impaired consciousness suggests a temperature below 32°C and is a medical emergency.

Initially, between 32°C and 35°C there is shivering and the patient feels cold. Paradoxically, as the core temperature falls, the patient may feel hot. Tendon and brainstem reflexes are reduced and pupils are fixed and may be dilated in severe hypothermia. The patient may appear dead.

Investigations

A low-reading thermometer is vital when diagnosing hypothermia. An ECG is essential to look for J waves.

Other ECG abnormalities include prolongation of the PR interval, QRS or QT interval. Death from hypothermia follows ventricular fibrillation.

Arterial blood oxygen levels may appear normal because  they are measured at room temperature. There may be metabolic acidosis or alkalosis.

Signs of intercurrent infection should be looked for with blood cultures, urinalysis, and chest X-ray.

Blood glucose may be high or low in hypothermia. Amylase levels and thyroid function should be checked.

Treatment

Mild hypothermia without impaired consciousness can be treated with gradual warming in a warm room with space blankets, warm fluids and oxygen. Alcohol causes peripheral vasodilation and hypoglycaemia and may increase confusion, so should not be used.

It can take several hours to achieve a normal body temperature. Arrhythmias and metabolic abnormalities need treatment. Immersion of one forearm in water at 43°C is sometimes recommended.

Severe hypothermia requires gradual warming at 0.5–1°C per hour. Slow-warmed fluids are used to correct metabolic imbalance.

Rapid warming can lead to peripheral vasodilation, shock and death.

Warming that is too rapid is signified by falling BP and pulse and rectal temperature. Respiration rate should be monitored at least half hourly.

Some specialists advocate more rapid warming in an ITU environment on the basis that the morbidity from hypothermia is directly related to the time spent hypothermic.

Resuscitation should be continued for at least 40 minutes in the event of cardiac arrest.

Hypothyroidism should be treated. Humidified air, gastric or peritoneal lavage or haemodialysis have been advocated by some but are rarely used.

Antibiotic therapy is recommended for those over the age of 65 with a temperature below 32°C, in conjunction with a urinary catheter to monitor renal function.

The complications often include pneumonia, disseminated intravascular coagulation and pancreatitis.

The prognosis depends on the degree of hypothermia and the age of the patient, but mortality is generally over 50 per cent in over-70s.

Prevention

The elderly who live alone should be encouraged to use heaters, extra clothing and extra blankets at night. The room temperature should be maintained at 21°C. A room temperature below 16°C is considered a risk for the elderly. Electric blankets can also be useful.

Hot water bottles are an alternative. Frequent warm drinks and hot food rather than cold can help during the day. Personal alarms worn around the neck can summon help quickly in the event of falls.

Grants and benefits are available for the elderly for heating and insulation and GPs can play an important role in encouraging the elderly to apply for these.

Dr Miller is a GP in west London

Resources

  • Winter Warmth Advice line (08000 857000).
  • Warm Front Scheme Fact Sheets. Department of Health (08000 720151).
  • Scotland Warm Deal and Central Heating Programme (08000 720150).
  • Energy Efficiency Advice Centre (0800 512012).
  • Help The Aged: The Cold Can Kill pack (01255 473999).
  • Winter Fuel payments helpline (0845 9151515).

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