Targeted Temperature Management / Post-Arrest Temperature Control
Targeted Temperature Management / Post-Arrest Temperature Control
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Maged Tanios, MD, MPH, MBA
Disclaimer: This protocol is an educational reference intended to support — not replace — institutional policy, pharmacy and therapeutics review, and individual clinical judgment. Verify current dosing, contraindications, and local formulary/practice constraints before adopting into an EMR or using in patient care. This protocol leans heavily on an internal MemorialCare Best Practice Advisory Committee (BPAC) discussion deck from August 20, 2024, which was itself a *discussion draft* proposing a system-wide shift away from routine cooling to 33°C toward a fever-prevention ("temperature control") default. Confirm whether that discussion reached a finalized local Policy & Procedure before treating the target/duration below as settled practice.
Overview
Targeted temperature management (TTM) — previously called "therapeutic hypothermia" — refers to maintaining a comatose post-cardiac-arrest patient's core temperature at or below normothermia (32–37.5°C) for at least 24 hours. The evidence base has shifted substantially: early trials (2002) suggested a large benefit from cooling to 33°C, but the larger, more rigorous TTM2 trial (2021) and pooled analyses found no mortality or neurologic benefit of 33°C over careful normothermia with fever avoidance. Current European Resuscitation Council/ESICM guidance reflects this: recommend preventing fever, insufficient evidence to mandate cooling to 32–36°C.
Table 1. Trial evidence summary
| Trial | Year | Population | Comparison | Result |
|---|---|---|---|---|
| TTM | 2013 | OHCA, any rhythm (n=939) | 33°C vs. 36°C, both ×28h, temp ≤37.5°C ×72h | No difference in mortality or neuro outcome |
| HYPERION | 2019 | OHCA/IHCA, non-shockable (n=581) | 33°C ×24h vs. normothermia (36.5–37.5°C) | Better neuro outcome with 33°C (10.2% vs 5.7% good outcome) — the outlier favoring hypothermia |
| TTM2 | 2021 | OHCA, any rhythm (n=1850) | 33°C vs. normothermia (≤37.5°C) with early fever treatment | No difference in mortality (50% vs 48%) or mRS 4–6 (55% vs 55%) |
| TTM + TTM2 pooled | 2022 | Individual patient data (n=2800) | 33°C vs. 36°C/normothermia | No difference, including shockable vs. non-shockable subgroups |
| HACA-InHosp | 2022 | IHCA, any rhythm (n=249) | 32–34°C ×24h vs. no active TTM (avoid fever >37.5°C) | No difference in mortality or favorable outcome |
| Taccone et al. | 2023 | OHCA, non-shockable — IPD meta-analysis of TTM2 + HYPERION | 33°C vs. normothermia | No significant difference in unfavorable outcome (90.0% vs 89.2%) |
The one trial favoring 33°C (HYPERION) has not been replicated by the larger pooled analyses — this is why current practice is trending toward fever prevention as the default, reserving deeper hypothermia for case-by-case exceptions rather than routine use.
Steps
- 01
Identify Candidates
- All comatose adults with return of spontaneous circulation (ROSC) after cardiac arrest — both shockable and non-shockable initial rhythms.
- Typical exclusions: known comorbid disease making 180-day survival unlikely; pre-arrest Cerebral Performance Category 3 or 4; admission temperature < 30°C.
- 02
Choose the Temperature Target Strategy
- Given the lack of consistent evidence for a mortality/neurologic benefit of cooling to 32–34°C, the current direction (per the evidence in Table 1 and the local BPAC discussion) favors a "temperature control" strategy: maintain ≤ 37.5°C for a minimum of 24 hours, with moderate hypothermia (33°C) reserved as an exception rather than the default — the specific criteria for that exception were flagged as an open discussion item locally and need to be finalized by the Section Editor.
- Whichever target is chosen, maintain it for at least 24 hours once achieved.
- 03
Avoid Targets Below 36°C When Any of These Apply
- Pregnancy
- Known intrinsic bleeding diathesis (e.g., hemophilia, von Willebrand)
- Acute intracranial bleeding and/or major head trauma
- Active significant bleeding
- Suspected or confirmed acute stroke
- Systolic BP < 80 mmHg despite fluids, vasopressor(s), and possibly inotropes/IABP
- Delay > 6 hours from ROSC to cooling initiation
- 04
Monitor Core Temperature Continuously
- Axillary or oral temperatures are inadequate for TTM — use a core monitoring method (bladder, esophageal, or pulmonary artery catheter).
- 05
Achieve and Maintain the Target
Available methods: cold (4°C) IV normal saline, ice packs (axillae, groin, neck), cooling blankets, cooling vests, intravascular devices (including ECMO where applicable). Do not use prehospital cooling with rapid cold IV fluid infusion — current guidance advises against this.
- 06
Sedate During Active Temperature Control; Manage Shivering
- Sedation is mandated during the active intervention period to prevent shivering, which both causes patient discomfort and works against temperature control.
- Even under a normothermia/fever-prevention strategy, be prepared to apply an active cooling device — 46% of the TTM2 trial's normothermia-arm patients still required device cooling to stay ≤ 37.5°C.
- 07
If Hypothermia Is Selected, Rewarm Slowly
- Maintain the hypothermic target until the planned intervention window ends, then rewarm in controlled increments (the TTM2 protocol used roughly one-third of a degree per hour) rather than rapid rewarming.
- After rewarming, maintain a normothermic target (roughly 36.5–37.7°C) through at least 72 hours post-arrest for patients who remain sedated or comatose.
- 08
Prevent Fever for the Full Post-Arrest Window
- Regardless of which target strategy was used, prevent fever (> 37.5°C) for at least 72 hours in patients who remain comatose — this is the one piece of current guidance stated with more confidence than the specific cooling target itself.
Algorithm
Scroll sideways to see the full algorithm.
EMR Order Set
- Temperature control/TTM order set trigger.
- Target temperature selection: default ≤ 37.5°C (temperature control); 33°C selectable only as a documented exception per local criteria.
- Duration order: minimum 24 hours at target; fever-prevention extension to 72 hours for patients remaining comatose.
- Sedation order for the active intervention period.
- Continuous core temperature monitoring device order (bladder/ esophageal/PA catheter) — axillary/oral temperature explicitly insufficient.
- Shivering assessment scale, structured field.
- Cooling device setup/standby order, regardless of target strategy.
- Sedation/analgesia dosing for the intervention window; antishivering medication per local protocol.
Build notes — target temperature and exception justification should be a structured, not free-text, field so the rate of 33°C-exception use can be tracked as a metric once this rolls out.
Adoption Notes
- This protocol's core recommendation (default to temperature control rather than routine 33°C cooling) reflects an internal discussion that was still in progress as of the August 2024 BPAC meeting — confirm with Emergency Medicine, Pulmonary/Critical Care, Cardiology, and Neurosciences leadership whether a final system-wide Policy & Procedure was adopted, and what the finalized 33°C-exception criteria are, before building this into a live order set.
- Ensure cooling device availability and staff familiarity even under a normothermia-default strategy, given the ~46% device-use rate seen in the TTM2 normothermia arm.
- Champion: pairs well with a joint EM/critical care/neuroscience post-arrest care committee, mirroring the BPAC structure already in place locally.
Success Metrics & Monitoring
Proportion of ROSC-comatose patients receiving temperature control, time to target temperature, fever incidence (> 37.5°C) during the protocol window, cooling-device utilization rate, and survival/neurologic outcome at discharge (CPC or modified Rankin Scale). Track via the critical care database and post-arrest care registry; review quarterly.
Suggested Reading
- [1]
Dankiewicz J, Cronberg T, Lilja G, et al. Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest. *N Engl J Med*. 2021;384(24):2283–2294. doi:10.1056/NEJMoa2100591. The pivotal TTM2 trial — no benefit of 33°C over careful normothermia; primary driver of the current shift away from routine hypothermia.
- [2]
Lascarrou JB, Merdji H, Le Gouge A, et al. Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm. *N Engl J Med*. 2019;381(24):2327–2337. doi:10.1056/NEJMoa1906661. The HYPERION trial — the one major trial favoring 33°C, in a non-shockable-rhythm population; not replicated by later pooled analyses.
- [3]
Greif R, Bray JE, Djärv T, et al. 2024 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. *Circulation*. 2024;150:e1–e100 (article number CIR.0000000000001288). doi:10.1161/CIR.0000000000001288. Current ILCOR consensus umbrella for post-arrest care generally.
- [4]
Taccone FS, et al. Individual patient data meta-analysis of the HYPERION and TTM2 trials in non-shockable-rhythm cardiac arrest. *JAMA Neurology*. 2023 (exact volume/pages as cited in the local MemorialCare BPAC source deck — full citation not independently verified against the local BPAC source deck).
- [5]
LA County EMS Agency. Targeted Temperature Management Guideline, Reference No. 320.1 (revised 2023-01-01). Regional EMS reference for the exclusion/contraindication criteria used in Steps 1 and 3.
- [6]
MemorialCare Physician Society. Post-Arrest Temperature Management BPAC Meeting (internal deck), August 20, 2024. Source of the trial summary table and the proposed local shift toward a temperature- control default — a discussion draft, not confirmed final policy.
Revision History
| Version | Date | Editor | Summary |
|---|---|---|---|
| 0.1 | 2026-07-19 | FunctionalHealth editorial team | Initial version grounded in the TTM source folder, including an internal MemorialCare BPAC discussion deck |
Disclaimer: This protocol is an educational reference intended to support — not replace — institutional policy, pharmacy and therapeutics review, and individual clinical judgment. Verify current dosing, contraindications, and local formulary/practice constraints before adopting into an EMR or using in patient care. This protocol leans heavily on an internal MemorialCare Best Practice Advisory Committee (BPAC) discussion deck from August 20, 2024, which was itself a *discussion draft* proposing a system-wide shift away from routine cooling to 33°C toward a fever-prevention ("temperature control") default. Confirm whether that discussion reached a finalized local Policy & Procedure before treating the target/duration below as settled practice.