Hypothermia

Hypothermia overview

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)

Example 1

ECG Hypothermia sinus bradycardia 1

Marked sinus bradycardia (30bpm) secondary to hypothermia


Example 2

ECG Hypothermia slow atrial fibrillation AF

Atrial fibrillation with slow ventricular response due to hypothermia


Example 3

ECG Hypothermia 3

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


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.

Example 4

ECG Subtle Osborn wave J wave hypothermia
  • Subtle J waves in mild hypothermia [Temp: 32.5°C (90.5°F)]
  • The height of the J wave is roughly proportional to the degree of hypothermia

Example 5

J waves Osborn Wave hypothermia temp 30°C

J waves in moderate hypothermia. [Temp: 30°C (86°F)]


Example 6

J waves Osborn Wave hypothermia temp 30°C

J waves in moderate hypothermia. [Temp: 28°C (82.4°F)]


Example 7

Osborn wave temp 26 hypothermia

Marked J waves in severe hypothermia [Temp: 26°C (78.8°F)]


QT Prolongation

Example 8

ECG Hypothermia long QT shivering artifact

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).

Example 9

ECG hypothermia shiver artefact bradycardia long QT

Shivering artefact in a patient with hypothermia (note also the Osborn waves, bradycardia, prolonged QT)


Related Topics


References

  • Slovis C, Jenkins R. ABC of clinical electrocardiography: Conditions not primarily affecting the heart. BMJ. 2002 Jun 1;324(7349):1320-3. [PMC1123277]

LITFL Further Reading


Advanced Reading


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Posted by Dr Ed Burns

Dr Ed Burns . Emergency Physician in Pre-hospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education. Ed is the force behind the LITFL ECG library | + Edward Burns | @edjamesburns

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