Periods of cold injury
The clinical presentation of frostbite is clearly divided into two consecutive stages:
- Pre-reactive (latent) period. Lasts from several hours to a day, from the moment of cold exposure until rewarming begins. The patient experiences paresthesia, burning, or numbness. The skin becomes pale and cold to the touch. Important: at this stage, it is impossible to accurately determine the depth of the injury. A severe degree can only be suspected if sensation is completely absent.
- Reactive period. Begins immediately after tissue rewarming. In the early phase (the first 12 hours), persistent vascular spasm is replaced by capillary paresis. Blood flow slows down, resulting in the aggregation of formed elements and thrombosis. It is at this point that secondary necrosis forms and systemic complications develop (intoxication, hypoproteinemia).
Classification by depth of injury
The true severity of the injury only becomes apparent in the reactive period. There are 4 degrees of frostbite:
- Degree I (superficial): Circulatory disturbance is observed without tissue death. After rewarming, the skin becomes hyperemic and warm. Edema is moderate and does not extend beyond the exposure zone. Sensitivity is preserved, and recovery occurs by days 5–7.
- Degree II (superficial): Death of the epithelium, but the germinative layer remains intact. The key symptom is the appearance of blisters with clear serous contents. The base of the blister is red and extremely painful to the touch. Epithelialization takes 1–2 weeks.
- Degree III (deep): Necrosis affects the entire thickness of the skin and subcutaneous tissue. Rare blisters form with hemorrhagic (bloody) exudate. Their base is blue-purple and completely insensitive to pricking. Spontaneous regeneration is impossible; granulations develop that require skin grafting.
- Degree IV (deep): Total necrosis of the skin, muscles, and bones. Gangrene develops. Edema rapidly increases within the first 1–2 hours and encompasses tissues far beyond the necrosis zone (e.g., when fingers are frostbitten, the entire hand or foot swells). A demarcation line forms in about a week.
Specific forms: trench foot
A special type of local cold injury is "trench foot". It develops from repeated and prolonged (several days) cooling of the lower extremities in high humidity conditions. The ambient temperature in this case may be above freezing (from 0 to +10 °C). The pathology manifests as debilitating aching pain, burning, and a feeling of numbness in the legs.
Principles of first aid and treatment
Timely assistance even in the pre-reactive period can prevent primary necrosis.
First aid administration:
- If active rewarming is possible, baths with water at 18–20 °C are used, gradually increasing the temperature to 39–40 °C over 20–30 minutes, supplemented by gentle massage with a sponge.
- If warm water is unavailable, apply a thermal insulation bandage (layers of sterile wipes, thick gray cotton wool, and a bandage). This implements the "thermos" principle, preventing heat loss while blood flow restores from within over 5–6 hours.
- The face (cheeks, nose, ears) is rubbed with the hand until red.
Conservative and surgical tactics: In the hospital, the mainstay of treatment is massive infusion therapy (dextrans, intra-arterial administration of antispasmodics, heparin for thrombosis prevention). For deep frostbite (degrees III–IV), a surgical approach is used: first, necrotomy (incision of the eschar) is performed to reduce intoxication and edema; 7–10 days later, necrectomy (excavation of necrotic tissue) is performed; and after 2–3 weeks, amputation with the formation of a functional stump is performed according to indications.
Briefly: answers to topical questions
What groups of pharmacological drugs are included in the complex infusion therapy regimen for frostbite in a hospital setting?
The complex infusion therapy regimen for frostbite in a hospital setting includes metabolic support drugs, antispasmodics, anticoagulants, and detoxification agents.
- Metabolic support drugs — dextran, mannitol, and sodium chloride.
- Antispasmodics — papaverine, nicotinic acid, and procaine (administered intra-arterially).
- Anticoagulants — sodium heparin for the prevention of thrombosis (administered intra-arterially, intravenously, and subcutaneously).
- Detoxification agents — volume replacement fluids (povidone with electrolytes) and crystalloid solutions.
In the late reactive period, blood components, immunological agents, parenteral nutrition mixtures, and antibacterial therapy (antibiotics, bacteriophages, chemical antiseptics) are additionally used.
What are the exact clinical indications for amputation in fourth-degree frostbite?
The exact clinical indications for amputation in fourth-degree frostbite are non-viability of the extremity and the development of severe infectious complications.
- Primary amputation — indicated for frostbite bordering on charring.
- Secondary amputation — performed after necrectomy or rejection of necrotic areas when conservative management of infection fails.
- Absolute indications — non-viability of the extremity due to severe frostbite, as well as a life-threatening progressive infectious process (sepsis, anaerobic infection).
In fourth-degree frostbite, amputation involves the removal of a segment proximal to the demarcation line and is the final stage of surgical treatment following necrotomy and necrectomy.
To easily distinguish blisters in deep versus superficial frostbite, remember the "live and dead base" rule: in degree II, the blister base is pink and painful ("live"); in degree III, it is purple and pain-free ("dead").
Class and exam questions
Why is it strictly forbidden to rub frostbitten areas with snow?
Snow does not warm tissues; instead, it cools them further. Moreover, ice crystals leave micro-abrasions on fragile skin, which opens the door for infection and significantly increases the risk of erysipelas.
How to distinguish degree IV frostbite from degree III in the first hours?
In the early stages, differential diagnosis is extremely difficult. However, degree IV is characterized by rapid, massive edema that, 1–2 hours after rewarming, spreads far beyond the necrosis zone.
What is the mechanism of action of a thermal insulation bandage?
The bandage works on the "thermos" principle. It does not generate heat on its own, but blocks heat loss, allowing tissues to gradually and evenly warm up from internal blood flow (on average over 5–6 hours).
What else to study on this topic
- Infusion therapy protocols in the early reactive period (dosages of heparin and antispasmodics).
- Surgical tactics: indications and technique for performing necrotomy and necrectomy.
- Systemic hypothermia (freezing): criteria for stuporous and convulsive forms.
- Trophic and occlusive vascular disorders as long-term consequences of cold injury.
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