March 15, 2015

Accidental Hypothermia

By Cameron Wangsgard, M.D.



  • Most important:
    • Remove clothes
    • Cover with dry warm blankets and bedsheets
    • Bair hugger and/or Arctic sun (no real difference between the two. Bair hugger easier to initiate in ED. Cover up everything, including face too)
    • Warm room / heat lamps
  • Second most important:
    • Warmed humidified O2
    • Warmed IVF (but each 1L at 42 degrees will only raise body temp ~0.3 degrees C)
  • Generally initiate these measures above for anyone less than 34 degrees (moderate hypothermia)
  • Other considerations: NG lavage, bladder irrigation, thoracic lavage, peritoneal lavage are all invasive and time consuming with only at best being moderately effective. The easiest to perform - NG lavage and bladder irrigation are really minimally effective.

How do I get warmed IVF?

How do I get warmed humidified O2?

  • Patient breathing on own?
    • Ask for a "blender". RTs can get this from upstairs. You can attach it to a facemask and provide high flow O2. This is the same device that we use to initiate high flow NC for our peds patients.
    • Many BiPAP machines have a warmer/humidifier attached in line. Check with your own department before to find out if this is the case.
  • Patient intubated?
    • Modern ventilators can provide warmed/humidified air. However, many EDs only have access to older ventilators so again, know what's in your own department.

Rewarming in critically ill/hemodynamically unstable/peri-code/code

  • ECMO (best option when able, but not available most places)
    • Page ECMO team early!
  • CVVH (way easier than dialysis to initiate. You need to be able to place a Meherker and a nephrology nurse able to bring and operate the machine. That's basically it.
  • Hemodialysis (hard to initiate - unlikely to be a feasible option)
  • Cardiac bypass (hard to intitiate - unlikely to be a feasible option)
    • All these methods can raise body temp at least 2-4 degrees C per hour.

Patient is bradycardic? Should I pace them?

  • In general, pacing is not indicated in the hypothermic patient. If they have a pulse, continue to rewarm and the bradycardia should resolve.
  • Atrial fibrillation is the most common arythmia of hypothermia. Will convert to sinus with rewarming.
  • Classic board exam question is bradycardia with osborn waves but only see this in ~30% if severe hypothermic patients.


  • Somewhat controverial. Some say no CPR for PEA as you could induce a dysrhythmia. Some say shock only once and if it doesn't work, don't shock again until at least 2 degrees warmer.
  • Most would say if there is no pulse, you should be doing CPR.
  • Every 2 minutes, if there's a shockable rhythm... shock! If it's still a shockable rhythm 2 minutes later on rhythm check, shock again! It doesn't take that long to do. Just make sure you continue to re-warm them during the code.
  • Be careful with meds. Consider only giving 1mg epi ONCE rather than repeat dosing over the course of the code. As they re-warm, they will vasodilate. If they have a bunch of epi from multiple rounds sitting in their vasoconstricted extremity, they could get a huge surge of epi all at once.

When should I call the code? When is the patient truly warm and dead?

  • Most textbooks would say 32 degrees - if there is still no pulse, resuscitation efforts should be terminated.
  • Alternatively K > 12 mmol/L warrants termination of resuscitation efforts.

What other interventions/testing should be done?

  • Does the patient have frostbite?
    • Patient needs aggressive rewarming of areas of frostbite. Consider NSAIDS, calcium channel blockers, and if there are signs of decreased perfusion in the hands or toes, they may be a candidate for tPA/heparin.
  • Was there trauma?
    • If patient was found down, consider imaging of head/c-spine if altered and obviously, perform a thourough physical exam.
  • Was this an intentional self-harm attempt?
    • Consider checking acetaminophen, salicylate, ethanol, EKG.
      • Incidentally, ethanol causes vasodilation making hypothermia more severe and re-warming techniques potentially less effective.
  • How long was the patient down?
    • Consider checking a Creatine Kinase - typical symptoms of rhabdomyolysis can be clouded by hypothermia.
  • Is this for sure accidental hypothermia? Could the patient have just incidentally been found outside for another reason? Maybe they were confused or just incidentally picked up outside.
    • Differential for hypothermic patient:
      • Accidental hypothermia (environmental exposure)
      • Hypoglycemia
      • Myxedema coma
      • Adrenal insufficiency
      • Sepsis
    • For these secondary causes, your goal is not active re-warming, but to treat the underlying cause. For example, treating myxedema coma primarily by active rewarming will result in vasodilation and secondary cardiovascular collapse. Focussed treatment would be removing cold clothes + warm blankets but not other active rewarming techniques + medical treatments (T3/T4, steroids, fluids, etc)

Further reading?


Tags: Core Content

Another great recent resource on the ECG manifestations from Dr. Smith’s blog (and Dr. Wangsgard–thanks for introducing me to this!):

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