From the Guidelines
The management of a patient in cardiac arrest due to hypothermia requires a modified approach focusing on rewarming while continuing resuscitation efforts, with the most recent guidelines from 2020 suggesting that standard BLS and ALS treatment should be provided along with preventing additional evaporative heat loss and rewarming techniques 1.
Key Considerations
- Begin CPR immediately and follow standard ACLS protocols, but with important modifications, such as delaying defibrillation attempts until the core temperature reaches at least 30°C (86°F) if initial attempts are unsuccessful 1.
- Medications should also be withheld until reaching this temperature threshold, as drug metabolism is severely impaired in profound hypothermia, although some studies suggest that vasopressor medications may be beneficial in increasing rates of return of spontaneous circulation (ROSC) 1.
- Active rewarming is the cornerstone of treatment and should be initiated promptly using multiple methods, including warm humidified oxygen, warm IV fluids, and external warming with forced-air warming blankets 1.
Rewarming Techniques
- In severe cases, more invasive rewarming techniques may be necessary, such as peritoneal lavage with warm fluids, thoracic cavity lavage, or extracorporeal blood warming using ECMO or cardiopulmonary bypass, which is the most effective method 1.
- Resuscitation efforts should continue until the patient is rewarmed to at least 32-35°C before considering termination, as the adage "a patient isn't dead until they're warm and dead" applies due to the neuroprotective effects of hypothermia 1.
Post-ROSC Care
- Once the patient achieves return of spontaneous circulation, they should be monitored closely for rewarming shock, electrolyte abnormalities, and acid-base disturbances that commonly occur during rewarming 1.
- The patient should be warmed to a goal temperature of approximately 32° to 34°C, and then maintained according to standard postarrest guidelines for mild to moderate hypothermia in patients for whom induced hypothermia is appropriate 1.
From the Research
Management of Cardiac Arrest due to Hypothermia
The management of a patient in cardiac arrest due to hypothermia involves several key considerations, including:
- The timing and duration of therapeutic hypothermia, with studies suggesting that it should be initiated as soon as possible after the return of spontaneous circulation (ROSC) or even during cardiopulmonary resuscitation (CPR) 2
- The target temperature, with recommendations ranging from 32 °C to 36 °C for at least 24 hours 3
- The method of cooling, with various options available, including cold fluids, ice packs, and specialized equipment for temperature control 2, 4
Initiating Hypothermia
Hypothermia can be initiated in the field or ambulance, and continued after hospital admission, as part of the global management of cardiac arrest patients 2. The use of therapeutic hypothermia is not limited to patients with shockable rhythms, but can also be considered for those with nonshockable rhythms or in-hospital cardiac arrest 4, 3.
Target Temperature Management
Target temperature management involves maintaining a constant temperature between 32 °C and 36 °C for at least 24 hours, with the goal of improving survival and neurological outcomes 3. The ideal timing and duration of this intervention are still being studied, but current recommendations suggest that it should be initiated as soon as possible after ROSC and continued for at least 24 hours 3.
Considerations and Controversies
There are still significant questions and controversies surrounding the use of therapeutic hypothermia in cardiac arrest patients, including the optimal target temperature, the duration of treatment, and the potential side effects 5. However, the current evidence suggests that therapeutic hypothermia can improve survival and neurological outcomes, and it is now recommended as part of routine post-resuscitation care 6, 3.