Hypothermia

This ECG displays the classic features of hypothermia: bradycardia, Osborn waves and shivering artefact.

Definitions

  • 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

Bradyarrhythmias

Patients with hypothermia may manifest a variety of bradyarrhythmias, 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

Osborn Waves

  • 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.
Typical Osborn waves

Typical Osborn waves

subtle osborn waves in mild hypothermia (temp 32.5)

Subtle Osborn waves in mild hypothermia (temp 32.5 degrees C)

J waves in moderate hypothermia (30 degrees C)

J waves in moderate hypothermia (30 degrees C)

marked osborn waves in severe hypothermia

Marked Osborn waves in severe hypothermia

QT Prolongation

  • Marked QT prolongation may occur with hypothermia and resolves with rewarming.

Prolonged QTc (620ms) due to severe hypothermia

Shivering Artefact

  • 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)

Related Topics

Further Reading

References

  • Cameron P, Jelinek G, Kelly AM, Murray L, Brown AFT. Textbook of Adult Emergency Medicine. Elsevier 2009.
  • Hampton, JR. The ECG in Practice (5th edition), Churchill Livingstone 2008.
  • 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.
  • Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.
  • Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.

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Comments

  1. Ken Grauer, MD says

    Great cases of hypothermia! Exquisite Osborne waves. May I use any of these ECGs for local teaching purposes? -- THANK YOU -- Ken Grauer, MD

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