Blisters on the skin, followed by the formation of black dry crusts

Introduction In the case of second-degree frostbite, it is a full-thickness skin frostbite, and the skin blisters form a black dry sputum.

Cause

(1) Causes of the disease

The main cause of frostbite is the long-term exposure of the human body to temperatures below 0 °C.

(B) the pathogenesis: long-term exposure to cold environment, local environmental humidity, decreased body resistance, body trauma or bleeding, long-term stillness of the frozen, long-term still after drinking, due to peripheral blood vessels expansion, heat dissipation and other factors can promote cold to the body Damage. In addition, the elderly and children are susceptible to this disease because of their poor heat regulation response.

After local skin is stimulated by the environment, strong contraction of blood vessels leads to tissue ischemia. The temperature continues to decrease, the tissue freezes, and the rapid freezing forms intracellular ice crystals, which slowly freeze to form intercellular ice crystals. Due to the formation of ice crystals, the microenvironment inside and outside the cell is changed, the cells are dehydrated, and the concentrations of intracellular electrolyte enzymes and sugars are increased. Out of freezing, during rewarming, the blood vessels dilate, and the blood quickly accumulates after entering the dilated microvessels, and the exudate increases, forming edema. Plasma extravasation, blood concentration, leading to thrombosis and microcirculatory disorders, make tissue more ischemic, and even lead to tissue necrosis. At the same time, due to increased tissue metabolism, increased oxygen demand, it is more likely to cause degeneration and necrosis of tissue cells. Therefore, the extent and extent of frostbite can only be observed after several days.

Make an accurate judgment. In addition, different tissues have different tolerance to cold. It is generally believed that nerves, blood vessels and muscles are the most sensitive, skin, sarcolemma and connective tissue are second, and bones and tendons are the most resistant to cold.

an examination

Related inspection

Skin fungus microscopy blood routine lesions

It occurs mostly in areas with poor peripheral blood circulation and exposed parts, such as the hands, feet, nose, auricles, cheeks, etc. The affected part was pale, cold, painful and numb. After rewarming, the local manifestations were similar to burns, but local swelling was generally not obvious. It can be divided into four degrees according to its depth and severity of damage.

Once frostbite: frostbite on the skin. The local skin is pale at first, gradually turning blue-violet, followed by redness, itching, tingling and paresthesia, and no blister formation. After about 1 week, the symptoms disappeared and the epidermis gradually fell off, leaving scars behind.

Second degree frostbite: frostbite for full-thickness skin. Local skin redness, itching, burning pain, blistering can occur within 24 to 48 hours, if there is no secondary infection, after 2 to 3 weeks, the blister is dry, forming a black dry sputum, and the wound has a parakeratotic neoplastic epithelial coverage Local may have persistent stiffness and pain, but leave no scars and convulsions.

Third degree frostbite: frostbite in the whole skin and subcutaneous tissue. The skin gradually turns from pale to blue and then to black. The skin feels disappeared, and edema and blisters appear in the surrounding tissues with frostbite, accompanied by severe pain and itching. After the necrotic tissue falls off, there is a wound, which is easy to be infected. It heals slowly, leaving scars behind and affecting function.

Four degrees of frostbite: skin, subcutaneous tissue, muscles and even bones are frostbitten. The sensory and motor function of the wound completely disappeared. The affected area is dark gray, and edema and blisters may appear at the junction with healthy tissue. Within 2 to 3 weeks, there is a clear line of necrosis, usually dry gangrene, but sometimes due to venous thrombosis, surrounding tissue edema and secondary infection, the formation of wet gangrene. Often leave disability and dysfunction.

Complications can occur in some patients with frostbite. The most common are secondary infections of local wound necrotic tissue, such as acute lymphangitis and lymphadenitis, acute cellulitis, and erysipelas. More severe cases are tetanus, gas gangrene and sepsis. In addition, there are a few cases of hepatitis, pericarditis, pyelonephritis and arthritis.

When the human body stays excessively in an extremely low temperature environment, it can cause systemic frostbite. This condition is called freezing and is rare. Early mental excitement, peripheral vasoconstriction, rising blood pressure, pale and cold skin, rapid heart rate, with chills. When the body temperature drops below 35 °C, various physiological functions are changed from excitement to inhibition; when the body temperature drops below 32 °C, the patient's expression is indifferent, insanity, breathing and heart rate are slowed down, muscle rigidity; when the body temperature drops to 29 °C When the following, the reaction is slow or even coma, blood pressure drops; when the body temperature drops below 26 ° C, ventricular fibrillation can occur, and finally the heartbeat, respiratory arrest

According to the medical history, the clinical manifestations can make a diagnosis.

Differential diagnosis

Blister or bullous damage: one of the manifestations of blistering or bullous polymorphic exudative erythema. Polymorphic erythema, also known as exudative polymorphous erythema, is an acute inflammatory skin disease with a complex cause. The rash is pleomorphic, often accompanied by mucosal damage, and its characteristic lesion is iris-like erythema. The disease is prone to spring and autumn and is prone to recurrence. The highest incidence rate is 10-30 years old.

Recurrent herpes zoster: Herpes zoster is an acute skin disease caused by varicella-zoster virus, herpes simplex virus type 1 and type 2, but patients are most concerned about herpes zoster For this problem, experts believe that herpes zoster and varicella are the same virus, in which the primary infection is varicella, and then the virus may enter the root ganglia of the spinal cord or the sensory ganglia of the cranial nerve. And lurking, but the latent virus can no longer cause symptoms, or be reactivated after a few years to cause herpes zoster. In addition, when the immune system is reduced due to some other diseases, or when an immunosuppressive product is used, it may cause the virus to recur.

Erosive blisters: Erosive blisters are herpes that are higher than the skin and contain water.

Small blisters on the skin with pain: Herpes zoster keratitis is a manifestation of herpes zoster's prodromal symptoms including general malaise, fever, chills and pain along the nerve skin distribution area, and small blistering of the skin in a linear arrangement; Suffering from neuralgia, I feel extremely persistent pain from tingling.

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