Environmental heat diagnoses
Background
- Heat related illnesses includes a wide range diagnoses from benign heat rash to heat stroke.
Types of heat dissipation
- Conduction: heat exchange between two surfaces in contact (placing ice pack in axilla)
- Convection: heat exchange between a surface and a fluid (fanning)
- Radiation: transfer of heat between body and environment through electromagnetic waves (relient on temperature gradient)
Heat Illness Etiology
All types are due to inadequate thermoregulation
- Classic Heat Illness
- Occurs without physical exertion
- Exertional
- Preceded by physical activity
Clinical Features
Heat Illness Types
- Heat cramps
- Muscles cramps due to electrolyte depletion
- Heat syncope
- Prolonged standing +vasodilation + volume loss --> decreased central venous return --> decreased CO--> decreased cerebral profusion pressure
- Heat exhaustion (temperature usually < 40°C)
- headache, n/v, weakness, vertigo, no CNS dysfunction
- Water depletion: inadequate fluid replacement to match fluid loss (sweat)
- Salt depletion: large volume of fluid loss is replaced with water (with inadequate salt)
- Heat stroke (temperature usually > 40°C)
- Similar to heat exhaustion plus CNS dysfunction (seizure, AMS), transaminitis, DIC, rhabdomyolysis
Differential Diagnosis
Environmental heat diagnoses
Management
- Heat cramps
- Heat syncope
- Heat exhaustion
- Heat stroke