The affected area should be re-warmed without delay, but only if re-freezing is not probable during transportation and the patient is not hypothermic.
Unnecessary handling of the affected area should be avoided after thawing.
Clinical features
Frostbite injuries
Stinging pain
Decreased or absent sensation
Pale, bluish or marble-like skin colour
White blotch on the skin is the first sign of frostbite injury of the face.
Clear or blood blisters
Severity cannot be estimated before thawing.
Classification of frostbite injuries: see table T1.
On fingers, frostbite is classified as severe if there are ischaemic changes in the middle phalanx of a finger, the distal phalanx of several fingers or any part of the thumb.
Classification of frostbite injuries of the skin (source: Lindroos L, et al. Finnish Medical Journal 2012;67(7):505-50)
Grade
Clinical picture
1.
Normal sensation, no blisters
2.
Oedema, clear blisters
3.
Decreased or absent sensation, no vital reactions, blood blisters
4.
Bluish and mottled skin, no sensation, only proximal but no distal oedema
Immersion injuries
An immersion injury is caused by prolonged exposure of distal body parts, typically the feet, to cold and wet conditions without freezing (non-freezing cold injury, NFCI; occurs in temperatures between 0 and +15°C). The injury is also known as "trench foot".
The usual exposure time is several days or weeks.
Numbness and gross oedema may occur in the affected limb during the warming process. This is followed by redness and severe pain.
The most serious immersion injuries cause ulceration and necrosis.
Care
Hypothermia is corrected before local frostbite injuries are treated. Moving of the distal body parts of a hypothermic patient should be avoided, because cold blood may, when entering the heart, cause arrhythmias.
The best treatment is rapid thawing in warm water (40-42°C) for 15-30 minutes or until circulation returns to the affected area.
Rapid thawing causes less tissue damage than slow gradual thawing: in rapid thawing the vasospasm is resolved, there is no development of thrombi, and the capillary circulation is preserved even if tissue oedema appears.
Re-freezing of thawed tissue is very harmful; thawing should not be attempted in nature if there is a risk of re-freezing during transportation.
As an analgesic, ibuprofen 800 mg 3 times daily is started if there are no contraindications. The need to manage severe pain after thawing should be reckoned with (opioid pain medication, e.g. morphine 4‒6 mg intravenously, for children 0.05-0.1 mg/kg).
Mechanical trauma should be avoided during the first aid treatment.
Frostbite injuries of 2nd to 4th grade are treated in a hospital.
The patient should be given warmed intravenous fluids. In severe cases, extracorporeal techniques are used.
Loss of sensation that continues even after warming up, as well as blood blisters and absence of Doppler signal suggest a severe frostbite injury.
Aspirin (ASA) 100 mg once daily and enoxaparin 40 mg once daily are used in the initial phase of treatment, for about a month.
Immediate angiographyis indicated if the frostbite injury is severe and it has developed less than 48 hours ago (preferably less than 24 hours ago) and there are no contraindications to the examination.
If an obvious occlusion is found in angiography, intra-arterial thrombolysis with alteplase should be applied; it has been proven to decrease the risk of amputation.
If thrombolysis is contraindicated, vasodilator infusion (iloprost) is a good alternative.
After thawing, the removal of blisters is important.
Tetanus prophylaxis should be taken care of.
Daily bathing of the affected area with povidone-iodine is adequate local treatment. As far as fingers are concerned, just polyurethane dressings may be used.
A swollen limb should be elevated and kept in a splint in its functional position.
In extensive injuries, antimicrobial prophylaxis (cephalexin) is used.
Dry gangrene is allowed to demarcate a few weeks before surgical treatment. Moist gangrene, however, should be debrided due to the risk of infection.
Late symptoms of frostbite may include paraesthesias, sensitivity to cold, profuse sweating, joint pain, white fingers and causalgia.