Hypothermia Versus Normothermia After Extracorporeal Cardiopulmonary Resuscitation for Out-of-hospital Cardiac Arrest

Temperature control is a key neurointensive care for post-cardiac arrest patients. Although therapeutic hypothermia has been shown to be effective in the past, recent large randomized controlled trials have failed to demonstrate its efficacy. The international guidelines recommend temperature control under 37.7°C. However, the optimal temperature control, i.e., hypothermia versus normothermia, remains controversial. Additionally, randomized controlled trials that examined temperature control after extracorporeal cardiopulmonary resuscitation (ECPR) are lacking.

ECPR is a resuscitation technique using extracorporeal membrane oxygenation (ECMO) for refractory cardiac arrest. In ECPR patients, ECMO using a heat exchanger can more rapidly achieve the targeted temperature as compared to other temperature control devices. Early cooling to achieve hypothermia after resuscitation is expected to be more effective for neuroprotection in the injured brain. Thus, the investigators hypothesized that hypothermia would be effective in ECPR patients.

Furthermore, ECMO can stabilize the respiratory and circulatory status. Therefore, hypothermia, which may have side effects such as electrolyte abnormalities and arrhythmias, may be safely performed by ECMO. However, ECMO requires the administration of anticoagulants; therefore, it has the risk of hemorrhagic complications. Among patients receiving ECPR, bleeding is a common complication due to its relatively difficult procedure, considering the fact that emergent cannulation is performed under resuscitation. Additionally, CPR-related complications can also result in bleeding. These complications may be enhanced by hypothermia. Therefore, hypothermia after ECPR could contribute to a favorable outcome, but it could also cause bleeding.

The SAVE-J NEUROTHERM trial is a cluster randomized trial that evaluated and compared the mortality risk, neurological outcomes, and adverse events between out-of-hospital cardiac arrest (OHCA) patients who underwent hypothermia and normothermia after ECPR.

Inclusion criteria

• OHCA
• Age of 18-75 years, known or estimated
• An initial cardiac arrest rhythm of ventricular fibrillation/pulseless ventricular tachycardia or pulseless electrical activity

Exclusion criteria

• ECMO initiated after sustained return of spontaneous circulation (ROSC) and patients with sustained ROSC before ECMO initiation
• OHCA of presumed non-cardiac etiology
• Time from emergency call or witnessed arrest to hospital arrival of >60 min
• Time from hospital arrival to ECMO initiation of >60 min
• Pre-hospital ECPR
• Unavailability of the ECMO heat exchanger for temperature control
• Glasgow Coma Scale score before temperature control of >8
• Core body temperature upon hospital arrival of ≤32ºC
• Surgical intervention before temperature control (e.g., surgical intervention for the primary disease or complications related to resuscitation/ECMO procedures)
• Do Not Attempt Resuscitation) order confirmed prior to temperature control
• Limitations in intensive care before temperature control
• Known cerebral performance category (CPC) of 3-4 before cardiac arrest
• Known chronic obstructive pulmonary disease with home oxygen therapy
• Known or suspected pregnancy
• Concomitant illness, such as malignancy, shortens life expectancy (180-day survival unlikely)
• Consent not obtained or withdrawn by the participant or surrogate
• Other reasons, physician's decision not to enroll the patient