Old & Cold: Domestic hypothermia in the elderly

Dr MA Razaque *

The winter is a hard time for the elderly people, particularly in the already ill-patients. When exposed to cold, they can become easily hypothermic.

Hypothermia (Greek, hypo=below and therme=heat) means below normal body temperature. It is, arbitrarily defined as a core body temperature of 35oC or below and is classified as mild (35o to 32oC), moderate (<32o to 28oC) or severe (<28oC).

The temperature can be recorded by a low-reading rectal thermometer. Hypothermia can occur in all age groups even if indoor, if the weather is cold and if their heat regulatory mechanisms for some reasons are inadequate.

The balance between heat production and heat loss in the body is regulated by the hypothalamus in the brain. Heat is generated in most tissues of the body and is lost by radiation (55%), by evaporation (30%), by conduction (15%), through airways (5%) and from the skin (25%).

During the cold weather, the demand for oxygen by the heart is increased. The peripheral vascular resistance is also increased, which in turn elevates the systemic blood pressure. Many old people live through winter in houses/rooms with temperature below the minimum recommended 18.3oC (65oF).

The body’s response to cold is more at risk in the early morning hours, during which death may occur. Thin elderly people have less insulation than fatter ones and are therefore, more likely to become hypothermic.

The incidence of domestic hypothermia is increased if they have serious underlying diseases.

The elderly people tend to have:
(a) Impaired thermo (heat) regulation due to autonomic neuropathy
(b) Reduced sense of temperature discrimination, thus-
(c) Tolerate cold conditions without much discomfort, resulting in severe hypothermia.

Causes:

Hypothermia may be caused / aggravated by the following factors:
1. Not feeling the cold e.g. brain damage, dementia, neuropathy, confusion etc.
2. Inadequate heat in the house e.g. Poor housing, poverty, fear of high fuel / electricity bill etc.
3. Inadequate protection from the cold e.g. unsuitable clothing
4. Immobility
5. Associated illnesses e.g. Diabetes, hypothyroidism, malnutrition etc.
6. Drug overdose e.g. Anti psychotics, antidepressants, tranquilisers etc.
7. Alcohol
8. Falls (if unable to rise from the floor, may remain still and cold till discovered).
9. Increased heat loss e.g. Burns, psoriasis etc.

Features of hypothermia:

Hypothermia may be suspected by the physical findings, but can only be confirmed by a low-reading rectal thermometer. The temperature of elderly hypothermic people may have been falling over a period of several days before being diagnosed.

On examination, the skin may be pale and cold to touch, even of the normally warm parts such as the abdomen and between the thighs. The face may look puffy and the voice often husky. There may be shivering. When sever the breathing is slow and shallow. The pulse volume is reduced, faint and become irregular.There may be loss of consciousness.

Management:

1. Remove the person from the cold environment and keep in a warm room.
2. Wrap in blankets including the head. The head should be covered since up to 20% of the body heat may be lost through the head.
3. Use of external re-warming such as heating blankets and heat lamps etc.
4. Do not use direct heat. (E.g. hot water bag or bottle) as this may cause shift of fluid causing collection of fluid in the lungs (Pulmonary Oedema).
5. Hot food and drinks should be given several times a day.

In Favourable cases, the patient re-warms spontaneously and rapidly without adverse effects. If severe or does not responds to treatments at home, the patient should be hospitalised.

Preventive measures:

1. During cold weather the rooms should be kept warm. The minimum safe temperature of rooms should be 18.3oC (650F), especially those at the top of the building.

2. Wearing appropriate warm clothing.

3. Wearing of hat or knitted woollen hat or cap even at indoor is advisable.

4. During the night electric over-blankets may be used.