- 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
Hypothermia may produce the following ECG abnormalities:
- 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
- ECG with the classic features of hypothermia: bradycardia, Osborn waves and shivering artefact.
Patients with hypothermia may manifest a variety ofbradyarrhythmias, including:
- Sinus bradycardia (may be marked)
- Atrial fibrillation with slow ventricular response
- Slow junctional rhythms
- Varying degrees of AV block (1st-3rd)
- Marked sinus bradycardia (30bpm) secondary to hypothermia
- Atrial fibrillation with slow ventricular response due to hypothermia
- It is usually most prominent in the precordial leads.
- The height of the Osborn wave is roughly proportional to the degree of hypothermia.
- Typical Osborn waves
- Subtle Osborn waves in mild hypothermia (temp 32.5 degrees C)
- J waves in moderate hypothermia (30 degrees C)
- Marked Osborn waves in severe hypothermia
- 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).
- Shivering artefact in a patient with hypothermia (note also the Osborn waves)
- Slovis C, Jenkins R. ABC of clinical electrocardiography: Conditions not primarily affecting the heart. BMJ. 2002 Jun 1;324(7349):1320-3. Review. PMID: 12039829. Full text.
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Hampton, JR. The ECG In Practice, 6e
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
- Wagner, GS. Marriott’s Practical Electrocardiography 12e
- Chan, TC. ECG in Emergency Medicine and Acute Care
- Mattu, A. ECG’s for the Emergency Physician
LITFL Further Reading
- ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis –alphabetical diagnostic approach to the ECG
- ECG CLINICAL CASES — ECG’s placed in clinical context with a challenging Q&A approach
- 100 ECG Quiz — Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS — the best of the rest
- LITFL ECG IMAGE Database — Searchable database of LITFL ECG’s
- ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
- ECG Exam Template — a framework for answering ECG exam questions.