When to Apply a Warming Blanket
Warming blankets should be applied to patients with a core temperature below 36°C, with the specific warming strategy determined by the severity of hypothermia and the patient's clinical condition. 1
Assessment of Hypothermia Severity
Hypothermia severity guides warming intervention selection:
| Hypothermia Level | Core Temperature | Clinical Signs | Warming Approach |
|---|---|---|---|
| Cold stress | 35-37°C | Alert, possibly shivering | Passive rewarming |
| Mild hypothermia | 32-35°C | Altered mental status, shivering | Passive + active external warming |
| Moderate hypothermia | 28-32°C | Decreased responsiveness, ±shivering | All available passive and active methods |
| Severe/profound | <28°C | Unresponsive, appears lifeless, slow vital signs | Emergency intervention with all methods |
Warming Protocol Algorithm
Prehospital Phase
- All trauma patients should receive immediate Level 1 warming techniques (passive warming) 1
- Remove wet clothing and protect from environmental exposure
- Apply insulation from ground, cover head/neck, and shield from wind with plastic/foil layer 1
Hospital Phase (Trauma Bay/ED)
Measure core temperature during primary survey
If temperature >36°C:
- Apply two warm blankets
- Monitor temperature every 15 minutes
- Continue passive rewarming
If temperature <36°C:
- Initiate Level 2 warming strategies (heating pads, radiant heaters, warming blankets)
- Monitor temperature every 5 minutes
- Consider providing high-calorie foods/drinks if patient is alert 1
If temperature <32°C:
- Activate emergency response system
- Apply all available passive and active warming methods
- Handle patient gently to prevent arrhythmias
- Consider Level 3 rewarming for temperatures <32°C (cavity lavage or extracorporeal circuits) 1
During Patient Transfer/Observation
- Continue appropriate warming strategies throughout transfer
- Maintain warming until core temperature reaches 36°C
- Cease rewarming after reaching 37°C to avoid overheating complications 1
Safety Considerations
- Burn prevention: Place insulation between heat source and skin, follow manufacturer instructions, and monitor frequently for burns 1
- Avoid body-to-body rewarming as it is less effective than other active warming techniques 1
- Handle patients with moderate to severe hypothermia gently to prevent arrhythmias
- Monitor for complications of hypothermia including coagulopathy and cardiac dysfunction
Special Circumstances
- Perioperative patients: Apply warming blankets preoperatively, as early warming with self-warming blankets has been shown to be more effective than intraoperative forced-air warming alone in preventing postoperative hypothermia 2, 3
- Trauma patients with wet clothing: 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 impaired cardiovascular function, coagulopathy, and respiratory compromise. Early recognition and implementation of appropriate warming strategies based on hypothermia severity can significantly reduce morbidity and mortality.