Is direct rewarming of the head or neck recommended in cases of severe hypothermia?

Management of Severe Hypothermia: Direct Head and Neck Rewarming Not Recommended

Direct rewarming of the head or neck is not recommended in cases of severe hypothermia and should be avoided in favor of more effective active core rewarming techniques. 1, 2 Instead, patients with severe hypothermia (core temperature <28°C) require emergency intervention with comprehensive active core rewarming methods.

Hypothermia Severity Classification and Appropriate Interventions

Hypothermia management should be guided by severity:

Severity Level	Temperature	Clinical Signs	Recommended Approach
Cold stress	35-37°C	Alert, possibly shivering	Passive rewarming
Mild	32-35°C	Altered mental status, shivering	Passive + active external warming
Moderate	28-32°C	Decreased responsiveness, ±shivering	All available passive and active methods
Severe/profound	<28°C	Unresponsive, appears lifeless	Emergency intervention with active core rewarming

Evidence Against Head/Neck Rewarming

Research specifically examining cranial-neck rewarming has shown it to be ineffective. A study comparing passive rewarming to cranial-neck rewarming and combined cranial-neck with inhalation rewarming found no significant differences in:

• Magnitude of afterdrop
• Duration of afterdrop
• Overall rewarming rate 3

Recommended Rewarming Approach for Severe Hypothermia

For severe hypothermia (<28°C), the following approach is recommended:

1. Immediate interventions:

   • Activate emergency response system
   • Handle patient gently to prevent arrhythmias
   • Remove wet clothing
   • Protect from further heat loss

2. Active core rewarming methods (Level 3):

   • Warmed intravenous fluid infusions
   • Heated humidified oxygen
   • Body cavity lavage
   • Extracorporeal blood warming (ECMO preferred for cardiac arrest) 1, 2, 4

3. Concurrent external rewarming:

   • Apply insulation between heat sources and skin
   • Use chemical heat blankets, forced air warming systems
   • Monitor frequently for burns 1

Pitfalls and Caveats

• Avoid body-to-body rewarming as it is less effective than other active warming techniques 1
• Monitor for rewarming shock which can occur when peripheral vasodilation causes hypotension
• Handle patients gently as severe hypothermia increases risk of ventricular fibrillation
• Avoid direct head/neck rewarming as it has not shown benefit and may divert attention from more effective interventions 3
• Continue rewarming until core temperature reaches 36°C but cease after reaching 37°C to avoid overheating complications 2

Special Considerations for Trauma Patients

For trauma patients with hypothermia:

• Prevention should be emphasized first, as it becomes more difficult to rewarm once considerable heat is lost 1
• If unable to remove damp clothing immediately, active rewarming through the clothing using chemical heat blankets, plastic/foil layers, and insulative blankets is reasonable 1
• Hypothermia is an independent risk factor for mortality in trauma patients, associated with coagulopathy and cardiac dysfunction 2

In conclusion, while selective brain cooling (cooling the head and neck) may have applications in traumatic brain injury management 1, the reverse approach of directly rewarming the head or neck has not been shown to be effective for severe hypothermia and should not be used as a primary rewarming strategy.