No Neurologic Benefit for Longer Temperature Management After Cardiac Arrest

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Although previous research has confirmed optimal temperature for cooling, optimal duration is still under debate.
Although previous research has confirmed optimal temperature for cooling, optimal duration is still under debate.

There is no difference between 24- and 48-hour targeted temperature management (TTM) at 33°C in regard to improvement in 6-month neurologic outcome among unconscious survivors of out-of-hospital cardiac arrest, according to findings from a multicenter, randomized, clinical superiority trial published in JAMA.

Researchers designed a multicenter trial to assess the long-term neurologic outcomes experienced by patients managed with TTM for 48 hours at 33°C compared with outcomes associated with TTM management for 24 hours. The investigators randomly assigned 355 patients in a 1:1 ratio to 1 of 2 groups: 48-hour TTM at 33°C ± 1°C (n=176) or 24-hour (n=179) TTM. A total of 351 patients (99%) completed the trial.

A marginally greater favorable outcome was observed in the 48-hour patient group (69%) compared with the 24-hour group (64%); however, this finding was not statistically significant. There was no significant difference between the groups in regard to 6-month mortality or time to death (hazard ratio, 0.79; 95% CI, 0.54-1.15; P =.21).

The investigators observed more adverse events in the 48-hour group (97%) compared with the 24-hour group (91%; difference, 5.6% [95% CI, 0.6%-10.6%]; relative risk, 1.06 [95% CI, 1.01-1.12]; P =.04). Also, patients in the 48-hour group had a longer median length of stay compared with the 24-hour group (151 vs 117 hours; P <.001).

The investigators noted several limitations to this study, including that the sample size calculation with "a 15% absolute difference in the primary outcome may have increased the risk of a type II error." An inability to blind the intensive care unit staff to the group receiving treatment represented another potential study limitation.

In conclusion, the investigators believe further research in this patient population is necessary, as their study "may have had limited power to detect clinically important differences."

Reference

1. Kirkegaard H, Søreide E, de Haas I, et al. Targeted temperature management for 48 vs 24 hours and neurologic outcome after out-of-hospital cardiac arrest: a randomized clinical trial. JAMA. 2017;318(4):341-350.

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