When to stop cardiopulmonary resuscitation (CPR) in a patient with hypothermic cardiac arrest?

When to Stop CPR in Hypothermic Cardiac Arrest

Do not stop resuscitation in a hypothermic patient until they have been rewarmed, unless there are obvious signs of death such as rigor mortis or nonsurvivable traumatic injury. 1

Core Principle: "Not Dead Until Warm and Dead"

Victims of accidental hypothermia should not be considered dead before rewarming has been provided unless there are signs of obvious death. 1 This is a Class 1 recommendation from the American Heart Association, representing the strongest level of guidance. The physiologic basis is that severe hypothermia (core temperature <30°C) causes profound CNS and cardiovascular depression that mimics death, but full neurological recovery remains possible even after prolonged cardiac arrest if the brain was hypothermic before arrest occurred. 1, 2

Specific Criteria to CONTINUE Resuscitation

You should continue CPR in hypothermic patients who meet ALL of the following:

• Core temperature <30°C (86°F) with cardiac arrest 1
• Absence of rigor mortis 1
• No nonsurvivable traumatic injuries (e.g., decapitation, massive crush injuries) 1
• No other characteristics that deem them unlikely to survive 1

Duration of Resuscitation Efforts

Continue CPR until the patient is rewarmed to at least 32-34°C, as defibrillation and return of spontaneous circulation are rarely successful below these temperatures. 3, 4, 5 Case reports document successful resuscitation after:

• 5 hours and 44 minutes of continuous CPR with complete neurological recovery 6
• 4 hours of external cardiac compression with full recovery 3
• Multiple cases of prolonged arrest with excellent outcomes when rewarming was achieved 2, 4, 5

Modified CPR Protocols for Prolonged Resuscitation

When continuous CPR is impossible during difficult evacuations or transport, intermittent CPR is acceptable based on core temperature: 2

• Core temperature <28°C or unknown hypothermic arrest: Alternate 5 minutes of CPR with ≤5 minutes without CPR 2
• Core temperature <20°C: Alternate 5 minutes of CPR with ≤10 minutes without CPR 2
• Use mechanical chest compression devices when available to maintain continuous CPR and avoid interruptions 2

Rewarming Targets and Defibrillation

Defibrillation attempts may be reasonable according to standard BLS algorithms concurrent with rewarming, but success is unlikely until core temperature reaches 30-34°C. 1, 3, 4 If ventricular fibrillation persists after a single shock, continue defibrillation attempts while actively rewarming. 1

Epinephrine administration during cardiac arrest according to standard ACLS algorithms concurrent with rewarming may be reasonable, though drug metabolism is significantly reduced below 30°C and repeated doses may accumulate to toxic levels. 1, 7

Rewarming Methods and Transport Decisions

Full resuscitative measures, including extracorporeal rewarming when available, are recommended (Class 1). 1 Extracorporeal life support (ECLS) provides the most rapid and effective rewarming with excellent circulatory support, avoiding complications of prolonged inadequate perfusion. 5 However, successful outcomes have been documented with conventional rewarming methods (warm IV fluids, warm humidified oxygen, peritoneal lavage) when ECLS is unavailable. 1, 3, 6

Transport to a facility with ECLS capability should be prioritized when feasible, as this may necessitate earlier transport than in normothermic cardiac arrest. 1

Critical Pitfalls to Avoid

• Never pronounce death based on clinical appearance alone in hypothermic patients—profound hypothermia causes marked bradycardia, respiratory depression, and fixed dilated pupils that mimic death 1
• Do not stop resuscitation due to prolonged downtime—the neuroprotective effects of hypothermia allow for extended arrest times with full recovery 2, 6
• Do not assume defibrillation failure means futility—ventricular fibrillation is often refractory until rewarming to 30-32°C 3, 4
• Avoid giving up on conventional rewarming methods if ECLS is unavailable—successful outcomes occur with persistent conventional rewarming and continuous CPR 3, 6

The Only Acceptable Reasons to Stop

Stop resuscitation ONLY when:

1. Obvious signs of death are present (rigor mortis) 1
2. Nonsurvivable traumatic injury exists 1
3. The patient has been successfully rewarmed to normothermia (≥32-34°C) and remains in refractory cardiac arrest despite appropriate ACLS interventions 1