74. Age-related alterations in thermoregulation

Page created on May 21, 2019. Last updated on May 31, 2019 at 15:15

The core body temperature of older people is lower than that of younger people (by approx. 0.5℃). Their tolerance of extreme temperatures is more limited. Most deaths related to hypothermia and hyperthermia occur in elderly, signifying the importance of this topic.

Thermoregulation depends on organ systems like the cardiovascular and respiratory systems, the functions of which deteriorate with age. Not only autonomic mechanisms of temperature regulation but also behavioural mechanisms are impaired in aged individuals.

Both hypothermia and hyperthermia can cause decompensation of heart failure.

Heat-related conditions:

The thirst sensation in elderly is impaired, which predisposes to hypovolaemia. Water-depletion type heat exhaustion and heat stroke can develop.

The sweating ability and heat sensation is also decreased.

Cold-related conditions:

Many heat-conserving functions are impaired in elderly. Behavioural mechanisms, involving seeking out warmer areas and putting on more clothes, is impaired. Several autonomic mechanisms are also impaired, like:

• Shivering thermogenesis
• Cold sensation
• Peripheral vasoconstriction

The BMR is also reduced, which contributes to the problem.

Elderly often present with atypical symptoms of hypothermia. An altered mental state is often common, potentially causing confusion, somnolence or stupor.

Fever in elderly:

The effector mechanisms of cold defence (mainly shivering and vasoconstriction) are also responsible for the temperature increase during fever. As these mechanisms are impaired in elderly, so is their capacity to induce fever. In general, elderly produce fevers more rarely than young people, and their fevers are often of lower temperature.

Source for most of the information on this page: https://www.karger.com/Article/Pdf/333148