Frostbite: First Aid

Frostbite - damage to tissues when they freeze. Primary manifestations can be deceptively benign. The skin can be white or with blisters numb; warming causes severe pain. With frostbite, gangrene may develop. Treatment includes a gradual warming in warm (40-42 ° C) water and a local effect. Self-amputation of severely damaged areas is possible. Sometimes surgical amputation is necessary, but the solution, often based on the data of visualizing methods of investigation, should usually be postponed for several months after the injury.

Frostbite usually develops at extremely low temperatures, especially at altitudes. Most often, the distal parts of the limbs and open areas of the skin suffer.

In cells and in the intercellular space, ice crystals are formed, essentially freezing the tissue and causing cell death. Adjacent, unfrozen areas of the body are under threat, because ischemia is possible because of local vasoconstriction and thrombosis. When reperfusion as warming occurs release of inflammatory cytokines (for example, thromboxanes, prostaglandins), further enhancing tissue damage.

Symptoms of frostbite

The damaged area, cold, hard, white and numb, becomes warm, reddish, swollen and painful. Bubbles are formed in 4-6 h, but the full amount of damage can appear in a few days. Bubbles filled with clear plasma indicate surface damage; proximally located blisters with blood indicate a deep lesion and a possible loss of tissue. Surface lesions heal without residual tissue loss. Deep frostbite causes dry gangrene with a hard black scab over healthy tissues; moist gangrene, with a gray, swollen and soft surface, is less common. Wet gangrene can become infected, it is not typical for dry gangrene. The depth of tissue necrosis depends on the duration and depth of freezing. Possible self-amputation of severely damaged tissues. All degrees of frostbite can lead to symptoms of neuropathy in the distant period: sensitivity to cold, sweating, nail growth and numbness [symptoms reminiscent of those in a complex regional pain syndrome (see the corresponding section), although any connection between these two pathological conditions not proved].

First aid with frostbites

In the field, frost-bitten limbs must be warmed up quickly by completely immersing the damaged zones in water, warm (to the touch tolerated) (<40.5 ° C). Due to numbness, warming up with an uncontrolled source of dry heat (eg fire, heating pad) can lead to burns. Rubbing can also damage tissues, it should be avoided. The longer the area remains frozen, the greater the damage in the end. However, thawing of the feet is impractical if the patient is forced to go some distance further to receive assistance, since thawed tissues are particularly sensitive to trauma during walking and, remaining frozen, they will suffer less than after thawing. If the thawing is forced out, the frozen zone is carefully cleaned, dried, and protected with a sterile compress; patients are given analgesics, if possible, warm the rest of the body.

In the hospital, the limbs are heated rapidly in large containers with circulating water, the temperature of which is <40.5 ° C, for 15-30 min. Thawing often ends a little earlier than necessary, since the pain can be very pronounced. You can use analgesics parenterally, including opioids. Patients are advised to perform light movements with a damaged limb during warming. Large transparent bubbles do not touch. Hemorrhagic blisters also do not open to avoid the secondary drying of deep skin layers. Buried blisters sanitize.

Anti-inflammatory measures can be effective (eg, aloe vera preparations every 6 hours locally, ibuprofen 400 mg every 8 hours inside). Damaged areas are left open to contact with warm air, the limbs attach an elevated position to reduce swelling. The advisability of using anticoagulants, low molecular weight dextrans and intra-arterial vasodilators (eg, reserpine, galazoline) has not been clinically proven. Phenoxybenzamine (10-60 mg once a day inside) - a-adrenoblocker long-acting - can theoretically reduce vascular spasm and improve blood flow.

Prevention of infection is of great importance. With moist gangrene, antibiotics of a wide spectrum of action are prescribed. If there is no vaccination data, tetanus toxoid is given.

Full nutrition is important for maintaining metabolic heat production.

Visualizing research methods (such as radionuclide scanning, MRI, microwave thermography, laser Doppler flowmetry, angiography) can help assess blood circulation and tissue viability and, thus, orient the treatment. MRI and especially magnetic resonance angiography (MRA) can determine the demarcation area before the demarcation is formed clinically, which will allow performing a full surgical sanitation or amputation earlier. However, whether early surgery improves long-term results is not yet clear. Usually, surgical treatment is postponed for the longest possible period, since after rejection of the black scab underneath, viable tissue is often exposed. "It's frostbitten in January - operate in July," says the old adage. Patients with severe frostbites should be warned that it may take several weeks to form a clear demarcation and final determination of the volume of necrotic tissue.

Whirlpool baths with a temperature of 37 ° C 3 times a day with accurate drying, rest and time are the best long-term treatment. Absolutely effective treatments for long-term effects of frostbite (such as numbness, sensitivity to cold) are not present, although chemical or surgical sympathectomy may be effective in the long-term symptoms of neuropathy.