Following cardiac arrest, it is suggested that targeted temperature management (TTM) be implemented; however, the duration to reach the target temperature differs from clinic to clinic. Specifically, researchers hypothesized that patients who achieved hypothermia more quickly would have better results than those who took longer to reach the goal temperature of 33°C compared to normothermia. Out-of-hospital cardiac arrest patients were randomly assigned to either targeted hypothermia (33°C), followed by controlled re-warming, or normothermia with early treatment of fever (body temperature,≥37.8°C) in this post-hoc analysis of the TTM-2 experiment. To this end, they tallied up each site’s average temperature at the 4 h (240 min) return of spontaneous circulation (ROSC). A 6-month all-cause mortality rate was the primary endpoint. At 6 months, a poor functional result was a secondary outcome (score of 4–6 on the modified Rankin scale).
The primary outcome was measured for 1,592 participants. There was no statistically significant difference in fatality rates between hospitals that reached their goal temperature faster and those that took longer on average (P=0.17). About 71 of the 145 patients (49%) who were assigned to hypothermia at the quickest sites had died, while only 68 of the 148 patients (46%) in the normothermia group had succumbed (relative risk with hypothermia, 1.07; 95% CI, 0.84-1.36). About 74/144 patients (51%) in the hypothermia group and 75/147 patients (51%) in the normothermia group had a poor functional outcome (relative risk with hypothermia 1.01 (95% CI 0.80-1.26).
The effect of TTM at 33 °C compared to normothermia and early treatment of fever was not substantially different when using a hospital’s average time to hypothermia.