In an adult with severe traumatic brain injury and refractory intracranial hypertension (>20 mm Hg) despite sedation, analgesia, osmotherapy, and controlled ventilation, should therapeutic hypothermia (moderate hypothermia to 32‑35 °C) be employed?

Therapeutic Hypothermia for Refractory Intracranial Hypertension in Severe TBI

In adults with severe traumatic brain injury and refractory intracranial hypertension (>20 mm Hg) despite first-tier treatments, mild hypothermia (34–35°C) may be considered as a last-resort intervention to lower ICP, but it should NOT be used if you can achieve adequate ICP control with controlled normothermia (36.0–37.5°C), as moderate hypothermia (32–35°C) worsens neurological outcomes despite lowering ICP. 1, 2

Primary Recommendation: Controlled Normothermia First

The 2024 ESICM/NACCS consensus strongly recommends implementing controlled normothermia (target 36.0–37.5°C) as part of Tier 1 and Tier 2 ICP management, BEFORE considering hypothermia. 1 This represents a fundamental shift from older approaches that moved directly to deeper cooling.

Tiered Temperature Management Algorithm

Tier 0 (Baseline):

• Treat any fever >38.0°C 1
• Standard sedation, ventilation, CPP >60 mmHg 1

Tier 1 (ICP-dependent, First-line):

• Implement controlled normothermia targeting 36.0–37.5°C using automated feedback-controlled devices 1, 3
• Titrate sedation/analgesia 1
• CPP 60–70 mmHg 1
• PaCO₂ 35–38 mmHg 1
• Consider osmotherapy and EVD 1

Tier 2 (Escalation):

• Continue controlled normothermia 36.0–37.5°C 1
• Individualize CPP goals 1
• PaCO₂ 32–35 mmHg 1
• Consider neuromuscular blockade 1

Tier 3 (Last Resort):

• Only if Tiers 1–2 fail: Consider mild hypothermia 35.0–36.0°C (NOT 32–35°C) 1
• Consider decompressive craniectomy 1
• Consider barbiturate coma 1

Critical Evidence Against Moderate Hypothermia (32–35°C)

The landmark Eurotherm3235 trial (2015) definitively showed that moderate hypothermia (32–35°C) for ICP >20 mmHg resulted in WORSE outcomes: 2

• Adjusted odds ratio for unfavorable outcome: 1.53 (95% CI 1.02–2.30, P=0.04) 1
• Favorable outcome (GOS-E 5–8): 26% in hypothermia group vs. 37% in control group (P=0.03) 1, 2
• Despite better ICP control (barbiturates needed in 44% hypothermia vs. 54% control), neurological outcomes were significantly worse 1, 2

Multiple meta-analyses confirm no benefit from prophylactic moderate hypothermia (32–35°C) on mortality or neurological outcome in severe TBI. 1

When Mild Hypothermia (34–35°C) May Be Considered

The 2018 French expert panel suggests considering TTM at 34–35°C ONLY for refractory intracranial hypertension despite medical treatments (Grade 2+). 1

Specific Parameters if Hypothermia is Used:

• Target temperature: 34–35°C (NOT deeper than 34°C) 1
• Duration: Individualized until resolution of brain edema, may exceed 48 hours 4
• Rewarming rate: Controlled, slow (0.1–0.2°C/hour) to avoid rebound ICP 4
• Patient selection: Focal TBI (hemorrhagic contusions) may respond better than diffuse injury 4

Critical Implementation Details:

If hypothermia is employed, you MUST: 4

• Use standardized cooling algorithms 4
• Aggressively manage shivering, infections, electrolyte disorders, arrhythmias 4
• Monitor for reduced cardiac output 4
• Maintain temperature variation ≤0.5°C/hour and ≤1°C per 24 hours 3, 5
• Continue cooling until brain edema resolves (often >5 days for better ICP control and less rebound) 1

Why Controlled Normothermia is Superior

Uncontrolled fever (>37.5°C) in severe TBI causes secondary brain injury through: 3, 6

• Increased cerebral metabolic demand 3
• Enhanced excitatory neurotransmitter release 3
• Increased free radical production 3
• Elevated intracranial pressure 3, 6

Hyperthermia is independently associated with: 1

• Higher mortality rates 1
• Unfavorable neurological outcomes 1
• Prolonged ICU and hospital length of stay 1

Controlled normothermia (36.0–37.5°C) provides neuroprotection WITHOUT the risks of deeper hypothermia. 1, 3

Common Pitfalls to Avoid

DO NOT:

• Use moderate hypothermia (32–35°C) as first-line therapy for elevated ICP—it worsens outcomes 1, 2
• Rely on antipyretics alone for temperature control in severe TBI—they are insufficient 3, 5
• Cool below 34°C—no additional ICP benefit and increased complications 1
• Initiate hypothermia with rapid cold saline infusion before trying other ICP treatments (as done in Eurotherm trial) 1
• Rewarm rapidly—use ≤0.25°C/hour to prevent rebound ICP 4, 7

DO:

• Implement automated feedback-controlled temperature management devices for precise control 1, 3, 5
• Use central temperature monitoring (bladder, esophageal, or PA catheter) 3, 6, 5
• Maintain strict normothermia (36.0–37.5°C) in Tiers 1 and 2 1
• Reserve mild hypothermia (34–35°C, NOT 32–35°C) for Tier 3 refractory cases only 1

Pediatric Considerations

In children with severe TBI, moderate hypothermia (32–34°C) is NOT recommended (Grade 1). 1 Randomized trials showed no benefit and increased risk of hypotension and reduced cerebral perfusion pressure. 1

Bottom Line

The evidence hierarchy is clear: Start with controlled normothermia (36.0–37.5°C) as part of standard Tier 1–2 ICP management using automated devices. Only consider mild hypothermia (34–35°C, staying as close to normothermia as possible) as a Tier 3 last-resort intervention when all other measures fail, and accept that while it may lower ICP, it carries significant risk of worse functional outcomes. 1, 2