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How a hallmark study on post-arrest temperature management led to a critical change in practice

Normothermia offers same benefit with less risk

By Marianne M. Rowland
February 12, 2024
It is amazing how research is so instrumental in informing our practice and supports best patient outcomes.

It was the end of a busy day shift in the critical care unit (CCU), and I had just returned from the emergency department after being part of a talented team of professionals who successfully achieved return of spontaneous circulation (ROSC) post-arrest on a patient. I accompanied the patient to the unit, adrenaline pumping, embracing the intricacy, intensity and detailed oriented care that ensures that no leaf is left unturned and the best outcomes occur for the patient inside the CCU. This is something that we CCU nurses thrive on.

I’m writing this perspective today, however, because five years ago the evidence supported a much different management for this patient than it does today. Five years ago, the research supported the induction of hypothermia or, in simpler terms, making our patients’ core body temperature 33 C for 24 hours. This meant infusing refrigerated IV fluids and immediately applying a cooling blanket to lower the patient’s body temperature while infusing high doses of sedatives, analgesics and, in most cases, a paralytic to stop the patient from shivering.

We thought that making the patient’s body cold would help mitigate the aftermath of decreased perfusion to the brain during the arrest. Furthermore, it would reduce intracranial pressure and improve the oxygen-supply demand by decreasing cerebral metabolism (Lusebrink et al., 2022). This hypothermic cooling strategy was not without risks, with the development of clots and cardiac arrhythmias being two of the most common.

However, in 2021, a hallmark study was released, known as the TTM2 trial, which compared hypothermia (cooling to 33 C) to normothermia (temperature less than 37.8  C). The study reviewed 1,850 patients who experienced out-of-hospital cardiac arrests and who were randomly assigned to either the hypothermia or the normothermia temperature management group (Dankiewicz et al., 2021).

The hypothermic group was immediately actively cooled to 33 C for 28 hours, whereas the normothermic group had the following strategy: initiate active cooling if the patient’s temperature reached 37.8 C (Dankiewicz et al., 2021). Cooling was set to target 37.5 C for 40 hours. After the cooling intervention, patients in the normothermic group had their temperature maintained between 36.5 and 37.7 C for 72 hours post-arrest, with or without active cooling (Dankiewicz et al., 2021).

The findings were convincing. There was no added benefit to reducing the chance of death from any cause at six months and no improved functional outcomes at six months if the patient was in the hypothermic group (Dankiewicz et al., 2021). Our management strategy changed to continuous monitoring of esophageal temperature, early administration of antipyretics to prevent fever and, yes, still in some cases, application of a cooling blanket to keep the patient’s temperature between 36.5 and 37.7 C.

It is amazing how research is so instrumental in informing our practice and supports best patient outcomes. Until the next great research article proves otherwise, I’ll enjoy the reprieve from the need for oversedation, paralytics and chilly bodies that the TTM2 study proved was not necessary.


Dankiewicz, J., Cronberg, T., Lilja, G., Jakobsen, J. C., Levin, H., … Neilsen, N. (2021). Hypothermia versus normothermia after out-of-hospital cardiac arrest. New England Journal of Medicine, 382, 2283–2294. doi:10.1056/NEJMoa2100591

Lusebrink, E., Binzenholder, L., Kellinar, A., Scherer, C., Schier, J., Kleeberger, J., … Orban, M. (2022). Targeted temperature management in postresuscitation care after incorporating results of the TTM2 trial. Journal of the American Heart Association, 11(21). doi:10.1161/JAHA.122.026539

Marianne M. Rowland, RN, BScN, is a clinical educator in the critical care unit of Woodstock Hospital in Ontario.