Post Cardiac Arrest: Targeted Temperature Management (TTM)
Cardiovascular, Critical Care / Resuscitation
- In treated out-of-hospital cardiac arrests, survival varies from 8 – 19% even in high performing systems.1 Recent reports have demonstrated significant improvements in outcomes over the past decade,1 likely due to large scale improvements in OHCA care.
- Post arrest care likely has important impacts on survival, but precise recommendations of best practice are not clear for many clinical questions.
- Two trials published in 2002, randomized comatose post-OHCA with a presumed cardiac etiology and initial shockable rhythm to mild therapeutic hypothermia (MTH; goal temperature 32-34°C), or usual care, and reported improved survival.3,4 It was theorized by some that the true benefit of MTH was in its ability to prevent hyperthermia, as opposed to a benefit of sub-normal temperatures.
- The Targeted Temperature Management randomized control trial was subsequently performed, enrolling unresponsive patients after OHCA, comparing of 33°C and 36°C.5 Patients of all initial rhythms (except for unwitnessed asystole) were included, although 79% of participants were of shockable rhythms. The study was unable to detect a difference in mortality or neurological outcomes, however no harm was seen in the group treated with a lower temperature target. This study compared two approaches and should not be interpreted that no temperature management is required.
- The ideal temperature target is the subject of significant debate.
Who should be treated with TTM?
- All patients resuscitated from cardiac arrest who are not responding to verbal commands, regardless of arrest location or initial cardiac rhythm, should have TTM initiated as soon as possible.
How should TTM be implemented?
- Prehospital initiation of TTM is not recommended.
- A target temperature between 33 and 36 degrees should be initiated and maintained as soon as feasible.
- In patients with STEMI for whom PCI is pursued: the temperature goal should be 36 degrees as lower temperatures may decrease the effectiveness of clopidogrel or ticagrelor
- In most patients this temperature target will require no active intervention in the ED setting. Although there is no evidence that one method of temperature regulation is superior, surface cooling, ideally with cooling blankets, is likely the most practical method to reduce and maintain temperature in ED patients below 36 degrees.
- TTM should be maintained between 33 and 36 C for at least 24 hours; beyond 24 hours, temperature should not be allowed to exceed 37.5C
- Patients should be transferred as soon as feasible to a regional critical care setting, ideally capable of invasive coronary procedures.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
More Detailed Guidelines
- Canadian Cardiovascular Society/Canadian Cardiovascular Critical Care Society/Canadian Association of Interventional Cardiology Position Statement on the Optimal Care of the Postarrest Patient
- Part 8: Post–Cardiac Arrest Care 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Daya MR, Schmicker RH, Zive DM, et al. Out-of-hospital cardiac arrest survival improving over time: Results from the Resuscitation Outcomes Consortium (ROC). Resuscitation. 2015;91:108-115. doi:10.1016/j.resuscitation.2015.02.003.
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by Emergency Care BC (formerly the BC Emergency Medicine Network) and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. Emergency Care BC is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. Emergency Care BC also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Jul 13, 2017
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