Frostbite Classification and Treatment
Frostbite is classified as superficial (affecting outer skin layers without permanent tissue loss) or deep (involving deeper tissues with varying degrees of permanent tissue loss), and treatment centers on rapid rewarming in 37-40°C water, protection from refreezing, and early consideration of thrombolytic therapy for severe cases. 1, 2
Classification System
Frostbite severity ranges across a spectrum from superficial to deep injury:
Superficial frostbite (frostnip): Affects only the outer layers of skin without permanent tissue loss, presenting with numbness, tingling, and pale skin that responds well to simple rewarming 1, 3
Deep frostbite: Involves deeper tissues with formation of ice crystals within cells that destroy membrane integrity, causing varying degrees of permanent tissue loss—often less than initial appearances suggest 1, 4
Second-degree frostbite: Characterized by blistering and edema after rewarming, typically resolves with conservative treatment in 8-16 days 3
Third-degree frostbite: Involves full-thickness skin injury with hard eschar formation, may require skin grafting or can heal with conservative management over 29-39 days 3
Fourth-degree frostbite: Extends to muscle and bone with tissue necrosis, frequently requires amputation 3
Critical caveat: Estimating severity is challenging in the first aid setting, and the amount of tissue loss is difficult to predict at initial presentation—healthy tissue may exist deep to eschar 1, 4
Immediate First Aid Management
Priority Assessment
If concurrent hypothermia exists, rewarm the core FIRST before treating frostbite, as rewarming extremities first can cause core temperature to decrease 1, 5
Remove all jewelry and constricting items immediately to prevent further injury as swelling develops 1, 5
Protect frostbitten tissue from mechanical damage—do not walk on frozen feet or use frozen hands for climbing whenever avoidable, as frozen tissue cannot sense ongoing damage 1, 5
Rewarming Protocol
Do not attempt rewarming if any risk of refreezing exists or if close to a medical facility, as refreezing causes catastrophic additional damage 1, 5
For severe/deep frostbite when rewarming is appropriate:
Immerse affected part in warm water at 37-40°C (98.6-104°F) for 20-30 minutes 1, 5, 2
If no thermometer available, test water against your wrist—it should feel slightly warmer than body temperature 1, 5
Never use water above 40°C as this causes further tissue damage 5
Air rewarming can substitute when warm water immersion is impossible 1, 5
For superficial frostbite (frostnip):
- Simple skin-to-skin contact with a warm hand is sufficient 5
Never use chemical warmers directly on frostbitten tissue, as they reach temperatures that cause burns 5
Post-Rewarming Care
Wound Management
Apply bulky, clean, dry gauze or sterile cotton dressings to affected areas and between digits 5
Wrap circumferentially but loosely to allow for swelling without constricting blood flow 1, 5
Do not debride intact blisters, as intact skin is an essential barrier against infection 1, 5
Pharmacologic Treatment
Administer ibuprofen (400-600mg every 6-8 hours in adults) to decrease prostaglandin and thromboxane production that causes vasoconstriction, dermal ischemia, and further tissue damage 1, 5, 2
Continue NSAIDs long-term for ongoing anti-inflammatory and anti-thrombotic effects 5, 6
Advanced Hospital-Based Treatment
Thrombolytic Therapy
The American Burn Association conditionally recommends thrombolytics for severe frostbite to reduce amputations and achieve more distal amputation levels 2
Early administration (≤12 hours from rewarming) is conditionally recommended over later administration for better outcomes 2
This treatment is most effective when given soon after injury and must be administered in a healthcare setting 1, 5
Specialized Care Requirements
Arrange prompt podiatry or hand surgery follow-up within 24-48 hours for moderate injuries, sooner if any concern exists 5
Frostbite patients frequently require ICU stays (average 5.9-8.5 days) and relatively long hospitalizations (9.5-10.7 days) 7
Long-Term Sequelae Management
Neuropathic Pain
Duloxetine is first-line pharmacologic therapy for chronic neuropathic pain following severe frostbite 6
Gabapentin/pregabalin may be considered as second-line options, though evidence is limited 6
Continue NSAIDs long-term to prevent ongoing vasoconstriction and dermal ischemia 6
Ongoing Protection
Previously frostbitten tissue has permanently altered thermoregulation and remains at high risk for recurrent injury 8
Patients must avoid re-exposure to cold environments and ensure proper insulation 8, 3
Critical Pitfalls to Avoid
Never allow refrozen tissue—this causes devastating additional damage and is the most important preventable complication 1, 5
Do not assume absence of pain means absence of injury, particularly in patients with diabetes or peripheral neuropathy who may have impaired sensation 5
Do not rush to surgical debridement—wait for sufficient time until wound demarcation is clear, as tissue loss is often less than initial appearances suggest 4, 3
Discharge from emergency department is safe only if no tissue ischemia exists on examination, tissue has been properly rewarmed, no refreezing risk exists, and the patient can protect affected areas from further trauma 5