Targeted Temperature Management After Cardiac Arrest
For adult patients who remain comatose after achieving return of spontaneous circulation (ROSC) following cardiac arrest, you should implement targeted temperature management (TTM) by selecting and maintaining a constant target temperature between 32°C and 36°C for at least 24 hours, regardless of the initial cardiac rhythm. 1, 2
Patient Selection Criteria
Apply TTM to all comatose patients (defined as lack of meaningful response to verbal commands) after ROSC, regardless of arrest location or initial rhythm. 1
Strength of Recommendation by Arrest Type:
Out-of-hospital cardiac arrest (OHCA) with shockable rhythm (VF/pVT): Strong recommendation - TTM is the only post-ROSC intervention proven to improve survival with good neurologic outcome 1, 2
OHCA with non-shockable rhythm (PEA/asystole): Weak recommendation based on very-low-quality evidence, but still suggested given the high mortality and limited treatment options 1
In-hospital cardiac arrest (IHCA) with any rhythm: Weak recommendation based on very-low-quality evidence from observational data only 1
Target Temperature Selection
Select a constant target temperature anywhere between 32°C and 36°C and maintain it strictly without variation. 1
The landmark TTM trial (939 patients) compared 33°C versus 36°C and found no difference in mortality (HR 1.06,95% CI 0.89-1.28) or neurologic outcome at 6 months (RR 1.02,95% CI 0.88-1.16). 1 This moderate-quality evidence demonstrates that any temperature within this range is acceptable, but the specific choice matters less than maintaining strict temperature control and preventing fever. 1
Practical Temperature Selection Algorithm:
Consider 36°C for patients with hemodynamic instability: TTM at 33°C causes more bradycardia, elevated lactate, and increased vasopressor requirements compared to 36°C 1, 2, 3
Either 33°C or 36°C is acceptable for hemodynamically stable patients: No survival or neurologic benefit has been demonstrated between these temperatures 1, 4
Avoid temperature variability: Stability at the chosen target is more critical than the specific temperature selected 2, 5
Duration of Temperature Management
Maintain TTM for at least 24 hours after achieving the target temperature. 1, 6
This recommendation is based on protocols used in the largest randomized trials, which used 12-28 hours of cooling. 1, 6 A 2017 RCT (355 patients) comparing 48 hours versus 24 hours of TTM at 33°C found no significant difference in 6-month favorable neurologic outcome (69% vs 64%, RR 1.08,95% CI 0.93-1.25, p=0.33), but the 48-hour group had more adverse events (97% vs 91%, p=0.04). 7
Post-TTM Temperature Control:
After the initial 24-hour TTM period, actively prevent fever by maintaining temperature <37.5°C until 72 hours after ROSC. 1, 6, 3 The TTM trial protocol used strict normothermia (<37.5°C) after the initial cooling period until 72 hours post-ROSC. 1, 6
Rewarm gradually at approximately 0.25-0.5°C per hour to avoid rebound hyperthermia and secondary brain injury. 6, 3
Implementation Protocol
Timing of Initiation:
Start TTM as soon as feasible after ROSC, once airway, breathing (including mechanical ventilation), and circulation are stabilized. 2, 8 However, do NOT use prehospital rapid infusion of large volumes of cold IV fluid - this carries a Class III (No Benefit) recommendation with moderate-certainty evidence. 1, 3
Temperature Monitoring:
Use continuous core temperature monitoring via esophageal, bladder, or pulmonary artery catheters. 3 Axillary and oral measurements are inadequate for TTM. 3
Use temperature control devices with feedback systems based on continuous core temperature monitoring - both surface cooling and endovascular cooling show equivalent outcomes. 3
Critical Pitfalls to Avoid
Allowing uncontrolled fever: Fever is associated with worse neurologic outcomes; active prevention is mandatory even after the initial TTM period 1, 3
Delaying coronary angiography for cooling: Primary PCI should not be delayed by temperature management and can be performed simultaneously with cooling initiation 3
Inadequate monitoring for complications: Watch for hypokalemia, thrombocytopenia, coagulopathy, arrhythmias, bradycardia, hyperglycemia, and increased infection risk 2, 3
Ignoring ECG changes: Monitor for J-point elevation (Osborn waves), QT prolongation, and ST-segment changes during hypothermia 3
Premature rewarming: Rapid rewarming may increase complications; maintain the recommended slow rewarming rate 6, 3
Special Considerations
Do not use prophylactic anticonvulsants, as no benefit has been demonstrated in RCTs and they may cause harm through prolonged sedation. 2 However, perform EEG promptly in all comatose post-arrest patients to diagnose and treat seizures if they occur (12-22% incidence). 2
For post-MI cardiac arrest patients, hypothermia slows antiplatelet drug absorption and reduces clopidogrel hepatic conversion, but cooling can be started in the catheterization laboratory during PCI. 3