Anna is a small, frail 89-year-old woman. She resides in a nursing home and receives regular nursing ...

There are a number of reasons why a slight increase in temperature in the elderly is clinically significant:
Basal temperature is often lower in the elderly.
The febrile response can often be blunted or absent. Any increase in temperature is therefore clinically remarkable and may indicate serious illness.
Physiologically, the thermoregulatory center in the hypothalamus is less effective at set-point regulation in the elderly. There are also alterations in the release of endogenous pyrogens. Finally, neurological responses in eliciting heat generation in the body can be diminished or absent.

Anna is at risk for metabolic acidosis. Anorexia is a common finding with fever. There is also a significant increase in metabolic rate with protein catabolism and lipolysis for energy production. With prolonged fever, these findings collectively lead to a state of metabolic acidosis.

Rapid cooling causes superficial vasoconstriction, which impedes heat loss. It may also generate shivering and thereby promote increased heat production.