Targeted Temperature Management at 33°C Versus Controlled Normothermia for In-hospital Cardiac Arrest

The IH-TTM trial is designed to determine whether survival with a favorable neurological outcome is improved by induced hypothermia at 33°C in comatose critically ill patients admitted after resuscitated in-hospital cardiac arrest (IHCA). Recent evidence suggests that targeted temperature management (TTM) at 33°C may provide no survival benefits compared to controlled normothermia in unselected patients with out-of-hospital cardiac arrest (OHCA). However, this evidence is relevant only to OHCA of presumed cardiac origin, chiefly witnessed and immediately followed by resuscitation efforts. Only scant data are available for cardiac arrest (CA) of other origins and for IHCA.

In a randomized clinical trial of patients with CA in an initial non-shockable rhythm, the subgroup with IHCA had significantly better outcomes when treated with TTM at 33°C versus controlled normothermia; nevertheless, the sample size was limited. Another randomized controlled trial done specifically in patients with IHCA failed to show benefits of TTM at 33°C compared to controlled normothermia but was underpowered. Thus, whether therapeutic hypothermia is indicated after IHCA remains unclear. IH-TTM will be the largest trial assessing TTM after IHCA.