Low-temperature burns can also be called low-temperature burns or hypothermic burns, which are burns of the skin and subcutaneous tissues at the contact area caused by the accumulation of heat due to prolonged exposure of the body to a heat source of less than high temperature, called low-temperature burns. It is a progressive damage from the superficial dermis to the deep dermis and subcutaneous layers of tissue. It is generally believed that 70℃ heat source can cause epidermal damage after 1 minute of continuous contact with the skin, and 44℃ heat source can cause irreversible damage to the basal cells of the skin after 6 hours of continuous contact. The temperature of low temperature burns is generally in the range of 44-51℃, and the degree of skin damage is positively correlated with temperature and contact time. Although the temperature of most heating products is usually kept within a range that is tolerable or even comfortable for normal people, prolonged contact can still lead to low-temperature burns. In recent years, with the increasing number of heating products, low temperature burns have become more frequent. Although most heating items are printed with the words “Beware of low temperature burns” or “Low temperature burns prevention”, there are still many people who get burned. Low temperature burns are more common in infants and young children, teenagers, diabetics and the elderly. These people have poor resistance to cold and use heating items more frequently. Infants and young children are less expressive, so if parents fail to take care of them, they can easily suffer from low-temperature burns. The skin of the elderly becomes thinner with age, and the skin tension, sensory function, external protection, and temperature regulation of the surrounding environment are poor, and the regenerative function is reduced or weakened, and the blood transport of the skin is slowed. Therefore, the elderly have a lower response to low temperature stimulation, and the continuous effect of low temperature can easily lead to burns. The adolescents are in the golden age of learning, excessive concentration or mental fatigue can lead to reduced sensitivity to temperature, so adolescents are also a high incidence of low temperature burns. Diabetic patients are also a high risk group for low temperature burns because of their vascular neuropathy and low ability to sense and defend against heat damage. Cryogenic burns have the following characteristics The blisters are often confined to the bones and are often mistaken for shallow second-degree burns, and are characterized by dark color, bloody blister fluid, a pale trauma base, dull or absent sensation, and in severe cases, deep bones, forming a flask with a small mouth and a large base. It is common in the lower extremities, especially in the lower legs and feet, and often remains untreated for a long time or becomes a chronic ulcer due to improper treatment. Treatment of low-temperature burns Unless the wound is small, conservative treatment is often difficult to make the wound heal in the short term, and most require surgery to repair the wound. Early after the occurrence of a low-temperature burn, the wound surface is moist, blisters form, and the basal pallor is seen after the wound surface is exposed or the epidermis is torn off, and the crust forms a leather-like change as the wound surface dehydrates and dries out in about 2 weeks. The scab has a shielding effect on the epithelial crawl around the trauma, and the trauma cannot repair and heal by itself when the scab has not melted off and the trauma base has not formed granulation. In general, the scab formed in low temperature burns starts to melt off after 3-4 weeks, secretions increase, the trauma surface liquefies, and the inflammatory reaction increases. At this time, the granulation barrier is not yet perfect, and before the local infection is effectively controlled, the infection can also make the injury continue to deepen, and even the injury reaches deep into the muscle and bone, making it difficult to eliminate the trauma without surgery.