Targeted temperature management after out-of-hospital cardiac arrest: who, when, why, and how?

OBJECTIVE To provide a succinct review of the evidence, framed for the emergency department clinician, for the application of targeted temperature management (TTM) for patients after out-of-hospital cardiac arrest (OHCA). SOURCES OF INFORMATION MEDLINE, EMBASE, and the Cochrane database were searched for prospective and retrospective studies relevant to the indications of TTM, optimal timing of TTM initiation, method of cooling, and target temperature. MAIN MESSAGE Two prospective interventional trials reported improved neurologically intact survival with the use of TTM (goal temperatures of 32°C to 34°C) compared with no temperature management in comatose OHCA patients with shockable initial cardiac arrest rhythms. A more recent, high-quality randomized controlled trial including OHCA patients with shockable and nonshockable initial rhythms compared TTM at 33°C versus TTM at 36°C. Despite the study being well powered, superiority of one target temperature over the other was not demonstrated. The benefit of TTM in patients with initial nonshockable rhythms is not clear; however, some observational studies have suggested benefit. There is no evidence that any particular method of temperature regulation is superior. The relationship between time and TTM initiation has not been well established. CONCLUSION Targeted temperature management, with a target temperature between 32°C and 36°C, as a component of comprehensive critical care is a beneficial intervention for comatose patients with return of spontaneous circulation after OHCA.