Accidental Hypothermia

Read on for a Review of OSU EM Conference, by Zach Adams

Accidental hypothermia is a rarely encountered patient presentation and critical to manage correctly.  Some main points to review from our lecture this week from the New England Journal of Medicine article by Brown, et. al (Brown DJ, Brugger H, Boyd J, Paal P. Accidental hypothermia. N Engl J Med. 2012 Nov 15;367(20):1930-8):

1. What can be expected with varying degrees of hypothermia?

Classification of Hypothermia

2. How is it managed?  The NEJM article does a great job in presenting an algorithm for their care:

Hypothermia Algorithm

Some important points to discuss:

  • Every measure to rewarm the patient in arrest should be undertaken – active/passive – to include calling CT surgery at our institution to discuss ECMO or bypass
  • While initiating external and internal re-warming measures (i.e. warmed IV fluids, bear hugger, etc.), consider placing a Zoll catheter to help with active internal rewarming
  • Consider terminating CPR in the hypothermic patient without vital signs in the following scenarios:
    • Core temperature >32 degrees Celsius
    • Serum potassium >10-12

3. How fast will various measures increase body temperature?

Impact of Temperature Increase by Technique

As always, pay attention to the ABCs.  If a patient requires mechanical ventilation, consider the underlying physiology of the patient.  They’re overall metabolic rate will be slow, so a typical minute ventilation may make them alkalotic rapidly.  These patients will likely be bradycardic, so when checking for vital signs, give it a good 30-45 seconds before you declare it’s time for CPR.  Dysrhythmias are common – the most common is atrial fibrillation.  Do we treat it in the acute phase?  No, rewarm the patient.  Other common dysrhythmias include ventricular tachycardia and ventricular fibrillation as the patient becomes more profoundly hypothermic.  Standard ACLS medications will be of no benefit in the severely hypothermic patient (<30 degrees Celsius), and medications should be withheld.  You may, however, consider 3 rounds of epinephrine and 3 rounds of cardioversion in such instances – anymore than this is likely not beneficial.

Finally, indications for ECMO (at our institution):

  • Hypothermic patients who have cardiac instibility and are not responding to medical treatment
  • Intractable cardiac arrest (VF or asystole)

Our clinical guideline can be found here OSU Accidental Hypothermia Protocol.