Clinical manifestations of ear frostbite include coldness, pallor, hardness, and numbness or loss of sensation in the frozen area. The extent and degree of injury is often difficult to determine because of the localized frozen state. The injured person has pale, cold skin, sometimes edema of the face and surrounding tissues, confusion or coma, muscle tonicity, dull or absent pupil reflex to light, bradycardia, arrhythmia, undetectable blood pressure reduction, atrial and ventricular fibrillation, and in severe cases, cardiac arrest. Frostbite mostly occurs in areas with poor peripheral blood circulation and exposed areas, such as hands and feet, nose, ears, cheeks, etc. The affected skin is pale, cold, painful and numb. After rewarming, the local manifestations are similar to those of burns, but the local swelling is usually not obvious. According to the depth and severity of the injury, it can be divided into four degrees. First-degree frostbite is superficial skin frostbite. The local skin is initially pale white, gradually turning blue-purple, followed by redness, itching, tingling and abnormal sensation, without blister formation. After about 1 week, the symptoms disappear and the epidermis gradually peels off, leaving no scarring after healing. Second-degree frostbite is frostbite of the whole skin. Local skin redness, itching, burning pain, may appear within 24 to 48h blisters, if no secondary infection, after 2 to 3 weeks, blisters dry up, the formation of black dry crust, after shedding the wound surface with incomplete keratinization of the new epithelium cover, local may have lasting stiffness and pain, but does not leave scarring and cramps. Third-degree frostbite The entire skin and subcutaneous tissue is frostbitten. The skin gradually changes from pale to blue and then to black. Skin sensation is lost, and edema and blisters appear in the tissue around the frostbite, with more intense pain and burning itching. The necrotic tissues fall off and leave a traumatic surface, which is prone to secondary infection. Healing is slow, leaving scarring after healing, and may affect function. Fourth-degree frostbite The skin, subcutaneous tissue, muscles and even bones are frostbitten. Sensory and motor functions are completely lost in the injured area. The affected area is dark gray, and edema and blisters may appear at the junction with healthy tissue. 2 to 3 weeks later, a clear necrotic demarcation line appears, usually as dry gangrene, but sometimes wet gangrene develops due to venous thrombosis, surrounding tissue edema, and secondary infection. Disability and functional impairment are often left behind. Complications can occur in some frostbite patients, the most common being secondary infections of localized traumatic necrotic tissue, such as acute lymphangitis and lymphadenitis, acute cellulitis, and dengue. More serious are tetanus, gas gangrene and sepsis, in addition, there are still a few complications of hepatitis, pericarditis, pyelonephritis and arthritis. When the body stays excessively in extremely low temperature environment, it can lead to generalized frostbite, a condition called freezing, which is rare. In the early stage, mental excitement, peripheral vasoconstriction, blood pressure rises, pale and cold skin, accelerated heart rate, with chills. When the body temperature drops below 35℃, various physiological functions turn from excitement to inhibition; when the body temperature drops below 32℃, the patient’s expression is indifferent, mental confusion, respiration and heart rate are slowed down, muscle tonicity; when the body temperature drops below 29℃, the reaction is sluggish or even coma, blood pressure drops; when the body temperature drops below 26℃, ventricular fibrillation can occur, and finally heart and respiratory arrest. Diagnosis 1.History of freezing, especially in a humid and windy environment. 2, early numbness of the frozen area, burning pain, itching or tingling after rewarming, etc., if there is necrosis, there is no feeling. 3, frostbite after rewarming clinical performance is divided into four degrees: Ⅰ degree: superficial skin frostbite, skin is erythematous, mild edema. Ⅱ degree: superficial skin and part of the deep frostbite, early congestion edema, followed by blister formation. Degree III: frostbite of the skin and subcutaneous tissue, with total skin necrosis, and the skin changing from pale to purple-brown to black. Degree IV: frostbite involving deep tissues, with dry necrosis of deep tissues and loss of function.