- Hypothermia is defined as a core body temperature of < 35 degrees centigrade
- Mild hypothermia is 32-35 degrees
- Moderate hypothermia is 29-32 degrees
- Severe hypothermia is < 29 degrees
ECG Changes in Hypothermia
- Bradyarrhythmias (see below)
- Osborne Waves (= J waves)
- Prolonged PR, QRS and QT intervals
- Shivering artefact
- Ventricular ectopics
- Cardiac arrest due to VT, VF or asystole
- Sinus bradycardia (may be marked)
- Atrial fibrillation with slow ventricular response
- Slow junctional rhythms
- Varying degrees of AV block (1st-3rd)
- The Osborn wave (J wave) is a positive deflection at the J point (negative in aVR and V1).
- It is usually most prominent in the precordial leads.
- The height of the Osborn wave is roughly proportional to the degree of hypothermia.
- Marked QT prolongation may occur with hypothermia and resolves with rewarming.
- Shivering artefact is seen as a “fuzziness” of the ECG baseline.
- It is not specific to hypothermia and may be seen with other conditions associated with tremor (e.g. Parkinson’s disease).
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