Hyperthermia

Case Presentation

It was July 20 in Houston and the fourth straight day that would have a high temperature above 100°F. Janice was running some errands and decided to stop by her mother's house. Janice's mother, Marian, was eighty-four and in pretty good health. She was able to keep up with her housekeeping and still tended a small garden in her backyard. Just that morning, Janice had told her mother not to spend too much time working in the garden today. Janice knew that the heat could be dangerous, especially to the elderly, and her mother's place didn't have an air conditioner, but Janice felt that her mother was alert enough to know her own limits.

When Janice reached her mother's house, she found her mother unconscious on the couch in the living room. All of the windows in the house were closed. Janice immediately tried to rouse her mother and was able to get her to say a few words, but Marian seemed delirious. Janice grabbed the telephone and called for help. The emergency services operator instructed Janice to apply cold wash cloths to her mother's forehead and face and if possible to position her mother in front of a fan while using a spray bottle to spray tepid water on her skin.

When the paramedics arrived Marian was conscious but confused and feeling nauseous. At the hospital the doctor told Janice just how lucky she was to have visited Marian at that moment. He informed Janice that Marian had suffered heat stroke, a form of hyperthermia and that Janice's quick action at the house had saved her mother's life. Marian was making rapid progress to recovery but was being given fluids and electrolytes intravenously and was going to stay in the hospital overnight for observation.

Case Background

Hyperthermia occurs when the body temperature increases without an increase in the set point of the thermoregulatory center in the hypothalamus. Heat exhaustion and heatstroke are two common forms of hyperthermia. Symptoms of heat exhaustion include thirst, fatigue, profuse sweat, and giddiness or delirium. Individuals with heat exhaustion generally have a normal or only slightly elevated body temperature and the symptoms are the result of the loss of water and electrolytes. Symptoms of heatstroke include a temperature of 104°F, absence of sweating, and loss of consciousness. If untreated, heat exhaustion precedes heatstroke, and heat stroke is often fatal. Treatment for hyperthermia consists of reducing the body temperature to normal. Special attention is placed on reducing the temperature of the brain as tissue damage can result if the body temperature rises above 109°F.

1			Define homeostasis and describe how it relates to hyperthermia.
2			Explain why elderly individuals with poor circulation would have a greater risk of suffering heat exhaustion or heatstroke.
3			Explain why spraying water on the skin while sitting in front of a fan would lower body temperature.
4			When attempting to lower a person's body temperature in response to hyperthermia one should avoid treatments that induce shivering or vasoconstriction. Why?