Another Look at Hypothermia for Out-of-Hospital Nonshockable Cardiac Arrest

Two landmark studies conducted more than 20 years ago demonstrated that maintaining mild hypothermia targeting 33°C after cardiac arrest was associated with improved neurologic outcome. However, the TTM2 study, a recent large randomized, controlled trial, found that aggressively maintaining normothermia (36.5°C– 37.7°C) resulted in equivalent outcomes compared with mild hypothermia following out-of-hospital cardiac arrest (OHCA). In contrast, the HYPERION trial evaluated patients with both in-hospital and out-of-hospital cardiac arrest with a nonshockable initial rhythm and found clinically and statistically better outcomes at 33°C compared with normothermia. To clarify the role of therapeutic hypothermia in patients with OHCA and nonshocka…