Background

1. Hyperpyrexia is elevated body temperature.
2. Fever is elevated body temperature in response to a change in hypothalamic set point (infections).
3. Hyperthermia is elevated body temperature without a change in hypothalamic set point (heat illness, hyperthyroid, drugs).
4. The Second Law of Thermodynamics states that heat flows from hot to cold.
5. Heat transfer can occur through several processes:

a. Radiation

b. Conduction

c. Convection

d. Evaporation

Heat exhaustion

Symptoms: weak, dizzy, nauseated, headache, sweating, normal mental status. Heat exhaustion requires replacement of fluids and electrolytes.

Heat stroke

Symptoms: Hyperthermia + mental status changes. Heat stroke requires immediate cooling.