Cardiac Arrest & Hypothermia
Misdiagnosis of cardiac arrest in the pre-hospital setting is a hazard, and it is recommended that care providers perform a pulse check for a minimum of 30-45 seconds to prevent misdiagnosis of same (JRCALC, 2006). Commencing CPR on a hypothermic patient mistakenly diagnosed as being in cardiac arrest will almost certainly result in them arresting.
The compliance of the chest wall and indeed of the myocardium may be compromised, making compressions more difficult and less effective. The patient may also be less responsive to defibrillation, and in general, EMS providers are limited to delivering only 3 shocks in severely hypothermic patients. Paramedics are also precluded from administering medications to a hypothermic patient in cardiac arrest until core temperature has reached 30°C, and must then double the medication administration interval until core temperature reaches 34°C.
In the ED, re-warming efforts, in general, should be continued until core temperature is at least near normal. Because it may be impossible to identify if the hypothermia was the cause of arrest, or the arrest occurred prior to hypothermia, it is recommended that doctors exhaust all other causes of arrest prior to making a decision on termination of resuscitative efforts in hypothermic patients. (AHA, 2010)