# Temperature control after cardiac arrest Intervention · id `cardio:temperature-control-after-arrest` · Cardiovascular Atlas · release `5dcd9b263fe17744` (public) > General information from published sources, not medical advice, and not reviewed by clinicians. Check the cited source before relying on anything here. The atlas's own text and curation may be reused under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0, https://creativecommons.org/licenses/by-nc/4.0/): credit the atlas, and do not use it commercially. See the atlas About page. Text quoted from a source stays under that source's own terms, given as the source's reuse\_basis. The atlas's reuse terms do not cover it. The downloads list each quotation with its source in third\_party\_quotations. Browse, condition area: Acute care and long-term living ## In plain language After a cardiac arrest, a patient who stays in a coma may be treated in intensive care with controlled body temperature. The TTM2 trial compared two ways of doing it in 1900 adults in a coma after a cardiac arrest outside hospital, of presumed cardiac or unknown cause: cooling to 33 degrees C and then controlled rewarming, or keeping a normal temperature and treating any fever early. After 6 months, deaths were about equal (50% with cooling, 48% with normothermia), and heart rhythm problems that affected circulation were more common with cooling (24% against 17%). ## Technical summary The TTM2 abstract says targeted temperature management is recommended for patients after cardiac arrest but that the supporting evidence is of low certainty. The trial's comparator was targeted normothermia with early fever treatment, so the trial compares two temperature targets and does not test the absence of temperature management. ## Claims, with the population each applies to ## Context: Comatose adults resuscitated after out-of-hospital cardiac arrest of presumed cardiac or unknown cause (TTM2) Recipient: Adult; Population: Adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause (abstract wording). 1900 were randomly assigned and 1850 were evaluated for the primary outcome. The registry adds: unconscious with a FOUR-score below M4, stable return of spontaneous circulation for 20 minutes, eligible for intensive care without restrictions, and inclusion within 180 minutes of return of spontaneous circulation.; Care setting: Not stated in the abstract; the abstract gives no setting.; Geography: Registry locations in 14 countries; the registry also lists Luxembourg and the Netherlands as removed countries.; Life stage: Adults (abstract); the registry minimum age is 18 years and it gives no maximum age.; Follow-up: The primary outcome was death from any cause at 6 months (abstract). The registry gives 180 days. ### In TTM2, an open-label trial with blinded assessment of outcomes, 1900 adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause were randomly assigned to targeted hypothermia at 33 degrees C followed by controlled rewarming, or to targeted normothermia with early treatment of fever (body temperature of 37.8 degrees C or higher). The primary outcome was death from any cause at 6 months. A total of 1850 patients were evaluated for it: 465 of 925 patients (50 percent) in the hypothermia group had died, as compared with 446 of 925 (48 percent) in the normothermia group (relative risk with hypothermia 1.04; 95 percent confidence interval 0.94 to 1.14; P=0.37). Of the 1747 patients whose functional outcome was assessed, 488 of 881 (55 percent) in the hypothermia group had moderately severe disability or worse (modified Rankin scale score of 4 or more), as compared with 479 of 866 (55 percent) in the normothermia group (relative risk 1.00; 95 percent confidence interval 0.92 to 1.09). Arrhythmia resulting in hemodynamic compromise was more common in the hypothermia group (24 percent vs 17 percent, P<0.001); the incidence of other adverse events did not differ significantly. The authors conclude that targeted hypothermia did not lead to a lower incidence of death by 6 months than targeted normothermia. - Category: Effect - Evidence stage: Interventional - Certainty: Certainty not assessed - Applies to: Recipient: Adult; Population: Adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause (abstract wording). 1900 were randomly assigned and 1850 were evaluated for the primary outcome. The registry adds: unconscious with a FOUR-score below M4, stable return of spontaneous circulation for 20 minutes, eligible for intensive care without restrictions, and inclusion within 180 minutes of return of spontaneous circulation.; Care setting: Not stated in the abstract; the abstract gives no setting.; Geography: Registry locations in 14 countries; the registry also lists Luxembourg and the Netherlands as removed countries.; Life stage: Adults (abstract); the registry minimum age is 18 years and it gives no maximum age.; Follow-up: The primary outcome was death from any cause at 6 months (abstract). The registry gives 180 days. - Limitations: Abstract of the 2021 report only; the full text was not read (NEJM pages return HTTP 403 to scripts). The comparator was targeted normothermia with early treatment of fever, not an absence of temperature management, so the trial does not test whether managing temperature at all matters. The registry lists masking as TRIPLE but its description says the clinical team was not blinded to allocation; the abstract says open-label with blinded outcome assessment. 1850 of the 1900 randomized patients were evaluated for the primary outcome. The abstract names the Swedish Research Council and others as funders. PubMed lists no erratum for this record. - Last checked: 2026-10-15 - Sources: 1. Background: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, BACKGROUND, sentence 1. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Background stated in the abstract. 2. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 1, fragment 1 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 3. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 1, fragment 2 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 4. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 1, fragment 3 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 5. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 6. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 7. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 4, fragment 1 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 8. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 4, fragment 2 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 9. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, METHODS, sentence 5. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Design, population or outcome definition in the abstract. 10. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 1. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 11. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 2, fragment 1 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 12. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 2, fragment 2 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 13. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 3, fragment 1 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 14. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 3, fragment 2 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 15. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 3, fragment 3 of 3. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 16. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 4. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 17. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 5. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 18. Supports: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, RESULTS, sentence 6. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: Result stated in the abstract. 19. Background: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, CONCLUSIONS, sentence 1, fragment 1 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: The authors' conclusion in the abstract. 20. Background: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, CONCLUSIONS, sentence 1, fragment 2 of 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: The authors' conclusion in the abstract. 21. Background: Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (Publication, edition PubMed record (abstract and bibliographic data) fetched 2026-10-15 through NCBI E-utilities. No PMC copy is listed. The full text and the version of record were not fetched (NEJM pages return HTTP 403 to scripts).) Locator: Abstract, CONCLUSIONS, sentence 2. Retrieved 2026-10-15T13:48:58Z. Source state: Current. Snapshot hash: 3d492d428372f6c023d3222d13d0effef2ab05fbf054da69978f394b011e99bf. How it applies: The authors' conclusion in the abstract. ## Connected pages - Cooling to 33 degrees C compared with targeted normothermia in TTM2: Sudden cardiac arrest (`cardio:sudden-cardiac-arrest`) [a claim, not a settled fact; see claim `cardio:claim-ttm2-hypothermia-vs-normothermia` and its context] - Filed under this front: Emergency and acute care (`cardio:front-emergency-and-acute-care`) - Investigated in: TTM2 (`cardio:ttm2`) ## Provenance Content hash: 9c3a42d6d6e158b5f03851dee4dcbba7633db9db89addbeb24c2cc385baa0c4e Last substantive edit: 2026-10-15 Evidence last checked: 2026-10-15