Hypothermia is a core body temperature below 35 °C (95 °F) caused by cold exposure, immersion or illness that impairs heat production. As temperature falls, shivering stops, mental status declines and the heart becomes prone to ventricular fibrillation.
Key symptoms
- Shivering, cold skin and clumsy hands
- Confusion, slurred speech and poor judgment
- Drowsiness
- Shivering that stops as hypothermia deepens
- Paradoxical undressing in severe cases
What you find on exam
- Core temperature with a low-reading thermometer
- Level of consciousness and presence of shivering
- Slow pulse and breathing; take longer to check for a pulse
- Signs of frostbite or trauma
- Wet clothing and the surrounding environment
Tests
- Glucose
- ECG: slow rhythms, Osborn (J) waves, atrial fibrillation
- Electrolytes, especially potassium
- Blood gas and coagulation tests
Treatment basics
- Handle gently and keep horizontal; rough movement can trigger VF
- Remove wet clothing, insulate and add a vapor barrier
- Active rewarming: heat packs to the trunk, forced warm air, warm IV fluids
- Cardiac arrest: CPR and defibrillation per protocol
- Severe cases: transfer to a center with ECMO or bypass rewarming
Red flags
- Altered consciousness or loss of shivering
- Arrhythmia or cardiac arrest
- Core temperature below 30 °C (86 °F)
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Related guides
Sources: NASEMSO National Model EMS Clinical Guidelines; NREMT psychomotor skill sheets (EMT and Paramedic); AHA Guidelines for CPR and ECC. Written by Making Synapses. Making Synapses is not affiliated with these organizations.