Frostbite
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Direct answer
When living tissue actually freezes — extracellular ice crystals, cellular dehydration, then microvascular thrombosis completing infarction — the injury is frostbite, seen in India chiefly among soldiers at Siachen and high-altitude Ladakh, high-altitude pilgrims and the homeless in northern winters. The clinical grading runs from first degree (numb, erythematous skin with oedema) through second (clear fluid blisters) and third (haemorrhagic blisters with skin necrosis) to fourth degree (full-thickness extension to muscle and bone). Field management protects the part and defers thawing if refreezing is possible; definitive care is rapid rewarming in circulating water at 37 to 39 degrees Celsius for 15 to 30 minutes until the part flushes, with ibuprofen, tetanus cover, and never dry heat, rubbing or walking on a thawed part. Surgery is deliberately late — debridement waits weeks for clear demarcation ("frozen until proven dead"), with early escharotomy only for circumferential constriction or infection.
What you must remember
- Field rule that saves digits: do not begin thawing if refreezing is possible — the freeze-thaw-refreeze cycle destroys far more tissue than staying frozen; protect the part in a blanket or companion's clothing and evacuate.
- Rewarm protocol: immersion in gently circulating water at 37-39 degrees Celsius (a thermometer, not a hand estimate) for 15-30 minutes, ending when the part becomes red or purple and pliable; rapid rewarming, not gradual, is the standard.
- Forbidden list: dry or radiant heat (fires, heaters — insensate skin burns), rubbing with snow or massage (mechanical destruction), walking on thawed feet, and premature popping of blisters.
- Drug therapy worth quoting: ibuprofen 400 milligrams — inhibits thromboxane-mediated vasoconstriction and platelet aggregation in injured microvasculature; tetanus prophylaxis; consider daily warm-water hydrotherapy, and where available intravenous iloprost (a prostacyclin analogue with military experience in Europe) reduces amputation in severe grades; thrombolysis is used in selected cases within 24 hours.
- Blister logic: clear blisters — debride or leave per protocol, containing prostaglandin-rich fluid that damages tissue; haemorrhagic blisters indicate deeper dermal damage and are generally left intact.
- Grade the depth, then wait: fourth-degree injury — hard, woody, cyanotic, anaesthetic parts with eventual mummification — still waits weeks for demarcation; technetium-99 bone scan or MRI at 3-7 days helps predict tissue loss and plan amputation level.
- Surgical timing: early surgery only for compartment syndrome or wet gangrene; elective amputation after demarcation (commonly 4-8 weeks); escharotomy for circumferential eschar; long-term sequelae — cold sensitivity, numbness, hyperhidrosis and pain — counsel every soldier.
A typical exam case
A 26-year-old soldier is evacuated from a forward post at minus 30 degrees after 14 hours of exposure; both feet are white, hard and anaesthetic. Field protocol protected the parts dry — no snow-rubbing, no thawing — until the base hospital, where both feet are rewarmed in circulating water at 38 degrees Celsius for 30 minutes, ending with a purple flush and severe pain controlled with opioids. Ibuprofen is started, tetanus updated, clear blisters on the left foot are debrided, and haemorrhagic bullae on the right are left intact. Daily hydrotherapy begins; a technetium bone scan at day 5 questions the right forefoot. He is watched — no early debridement — and by week six the right forefoot has mummified to a clear line, where a transmetatarsal amputation with primary closure is performed. He is rehabilitated with a toe-filler prosthesis and counselled about lifelong cold sensitivity.
Where students slip
The two marks examiners hunt for: the refreezing rule (thaw only if refreezing cannot happen) and the no-rubbing rule — snow massage is the historical error MCQs still offer. The second slip is water temperature: the 37-39 degree window is narrow, and scalding is doubly dangerous because the tissue cannot feel it. The third is surgical patience — "early debridement of non-viable tissue" scores badly; the phrase frozen tissue should be treated as viable until demarcation is the expected teaching, with infection and compartment syndrome the only early operative reasons.
Frequently asked questions
At what water temperature is frostbite rewarmed?
Gently circulating water at 37-39 degrees Celsius for about 15-30 minutes, continued until the part flushes red or purple — never dry heat, fires or radiant heaters on insensate skin.
Why must rubbing or massage never be used?
Rubbing with snow or hands adds mechanical crush to frozen, crystalline tissue and worsens injury; rewarmed skin is fragile and massage shears already damaged capillaries.
When should thawing in the field be delayed?
When evacuation is uncertain and refreezing is possible — a thaw-refreeze cycle is more destructive than prolonged freezing, so the part is protected dry and rewarmed once, definitively.
What does haemorrhagic blistering signify?
Blood in the blisters indicates injury to the dermal vascular plexus — deeper damage than clear blisters — so they are left intact while demarcation is awaited.
Why is surgical debridement delayed in frostbite?
Frozen tissue mummifies and demarcates over weeks, and viable tissue often looks dead initially — early amputation risks losing salvageable tissue, so surgery waits for a clear line unless infection or compartment syndrome forces it.