What is the recommended approach for targeted temperature management (TTM) post return of spontaneous circulation (ROSC)?

Targeted Temperature Management Post-ROSC

For comatose patients after return of spontaneous circulation (ROSC), actively prevent fever by targeting a temperature ≤37.5°C for at least 72 hours, rather than pursuing aggressive hypothermia to 32-34°C. 1

Core Temperature Target

The most recent international consensus (2022) represents a significant shift from earlier aggressive hypothermia protocols:

• Target temperature ≤37.5°C (fever prevention) is now the primary recommendation for all comatose post-ROSC patients, regardless of initial rhythm or arrest location 1
• If active temperature control is used, maintain a constant target between 32-36°C, but the landmark TTM trial found no difference in mortality or neurological outcomes between 33°C and 36°C targets 1
• The 2022 guidelines downgraded the strength of hypothermia recommendations compared to 2015 guidelines, reflecting that normothermia (36°C) performs equivalently to hypothermia (33°C) when fever is prevented 1

Patient Selection

Apply temperature management to:

• All comatose (unarousable/unresponsive) adult patients after ROSC 1
• Both shockable rhythms (VF/pVT) - strong recommendation - and non-shockable rhythms - weaker recommendation 1
• Both out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) 1

Do not actively rewarm patients with spontaneous mild hypothermia after ROSC - this is associated with worse outcomes 1, 2

Duration and Timing

• Maintain temperature control for at least 24 hours after reaching target temperature 1
• Continue active fever prevention for at least 72 hours total after ROSC 1, 2
• No survival benefit was demonstrated for 48 hours versus 24 hours of cooling 1
• After the controlled temperature phase, rewarm slowly at approximately 0.25°C/hour 2

Method of Temperature Control

• Use temperature control devices with continuous feedback monitoring to maintain precise target temperature 1
• Surface cooling and endovascular cooling methods show equivalent outcomes 1
• Monitor core temperature continuously using esophageal thermometer, bladder catheter (in non-anuric patients), or pulmonary artery catheter 2
• Axillary and oral temperatures are inadequate for monitoring core temperature changes 2

Critical Pitfall: Prehospital Cooling

Do NOT use routine prehospital cooling with rapid infusion of large volumes of cold IV fluid immediately after ROSC - this is a strong recommendation against the practice 1

• Ten randomized trials involving 4,808 patients found no survival benefit from prehospital cooling 1
• Prehospital cold fluid infusion increases risk of re-arrest (RR 1.22,95% CI 1.01-1.46) 1
• No improvement in neurological outcomes at discharge 1

Monitoring for Complications

Key complications to monitor during temperature management:

• Coagulopathy - control all active bleeding before inducing hypothermia 2
• Cardiac arrhythmias - bradycardia during hypothermia may actually be beneficial and associated with good outcomes 1
• Increased vasopressor requirements - TTM at 33°C requires more vasopressor support than 36°C 1
• Hyperglycemia and metabolic disturbances 2
• Increased infection risk (pneumonia, sepsis) - prolonged hypothermia impairs immune function 2
• Elevated lactate levels - more common at 33°C versus 36°C 1

Practical Algorithm

1. Immediate post-ROSC: Assess mental status - if comatose, initiate temperature monitoring
2. Prevent spontaneous rewarming: Do not actively warm patients with mild spontaneous hypothermia
3. Select target: Choose ≤37.5°C (normothermia/fever prevention) as default; consider 32-36°C range if institutional protocols support active TTM
4. Initiate cooling: Use feedback-controlled surface or endovascular device; avoid prehospital cold fluid boluses
5. Maintain target: Continue for minimum 24 hours at target temperature
6. Rewarm slowly: 0.25°C/hour if hypothermia was used
7. Extend fever prevention: Continue active fever prevention to 72 hours total

Evidence Reconciliation

The evolution from 2015 guidelines (which strongly recommended 32-36°C TTM) 1 to 2022 guidelines (which recommend fever prevention ≤37.5°C) 1 reflects the impact of the TTM trial showing equivalent outcomes between 33°C and 36°C when fever is prevented in both groups. The critical insight is that preventing hyperthermia matters more than achieving hypothermia. 1