Or death.

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First, the mechanism of liquid nitrogen cryotherapy

Liquid nitrogen is colorless, odorless, non-flammable and non-explosive, and its boiling point is-196 degrees Celsius.

Cryotherapy is a biochemical process, which uses low temperature to act on tissues to make them necrotic, thus achieving the purpose of treatment. When human tissues are used at a low temperature below 0℃, the water in the tissues will freeze to form ice crystals. When the temperature is not very low, the tissue temperature drops slowly, and ice crystals are mainly formed outside cells. When the action temperature is very low, the tissue suddenly cools down, and ice crystals are mainly formed in cells. Ice crystals in cells are more deadly, so the lower the temperature of refrigerant, the greater the damage to cells. Ice crystals can cause mechanical damage to cells; The water in the tissue freezes, the cells dehydrate, and the electrolyte concentrates, so that the cells are poisoned and die.

Freeze-thaw period plays a more important role in cell death. During freezing and thawing, the ice crystals between cells melt first, thus absorbing a lot of heat energy around them, making the cells continue to freeze and form larger ice crystals. Slow thawing can strengthen and prolong this effect. Large ice crystals will cause more serious mechanical damage to cells, and at the same time, they can make cells stay in concentrated electrolyte environment for a longer time and accelerate cell death. Therefore, slow thawing is more destructive to tissues. The factors related to thawing speed include the temperature of refrigerant, the length of cryotherapy, the water content and thermal conductivity of tissue, and whether the blood supply of tissue is rich or not. If the blood supply is sufficient, the thawing will be accelerated.

Low temperature leads to blood circulation disorder, which is another factor of tissue necrosis caused by freezing. Low temperature causes vasoconstriction, blood flow slows down, and then thrombosis, blocking blood flow; Low temperature can directly damage blood vessels, cause edema, necrosis and even cell lysis of vascular endothelial cells, and cause tissue ischemia and death.

In addition, low temperature denatures lipid protein complex, which is the main component of cells, leading to cell rupture; The sudden drop of local temperature caused by low temperature leads to the temperature shock of cells, which is also the cause of cell death caused by freezing.

Tissue freezes to form ice hockey, and then naturally thaws, which is a freeze-thaw cycle. Experiments and clinical practice have proved that repeated freezing and thawing has more destructive effect than one freezing and thawing, which deepens the freezing depth and reduces the survival rate of living cells. The temperature of the refrigerant contacting the tissue is the lowest, and the temperature gradually increases to the edge.

It is generally believed that the highest temperature line of cell lethal hypothermia is -20℃. Various cells have different sensitivity to low temperature, for example, pigment cells are more sensitive, while skin tissue, bone tissue and nerve tissue are more tolerant.

At present, the refrigerants used for cryotherapy include liquid nitrogen (-196℃), solid carbon dioxide (-70℃) and freon (-60 ~-90℃), among which liquid nitrogen has low refrigeration temperature, low price, easy purchase and safe use.

The methods of liquid nitrogen cryotherapy include cotton swab method, contact method and spray method.

Liquid nitrogen is mainly used for surgical treatment and dermatosis treatment.

1, liquid nitrogen therapy

Routine disinfection before treatment, use freezer, aim nozzle tube at alopecia areata with a distance of 2 cm, spray evenly for 4-5 times, and stop when thin frost forms on the surface. After natural melting of liquid nitrogen, freeze-thaw for 2-3ci repeatedly, once a week, four times as a course of treatment.

2. During the treatment period

Most patients have mild itching, pain and flaky desquamation after 1 ~ 2 days of treatment, and the effect can be achieved by cooling 1 ~ 2 times. The exposure time of newborn hair to scalp is 7- 14 days, and the length is 0.4-0.5 cm. The new hair begins to be soft and white, then gradually turns into black hair, and the rest is coarse and black normal hair. After about 3 to 4 weeks, it looks like normal hair and grows gradually from the edge to the center.

3. Side effects of liquid nitrogen

The patient's scalp congestion and edema in the frozen area began to subside after 2 days, with slight itching and pain and flaky desquamation, which was tolerable and did not affect the treatment.

4. Mechanism of treating alopecia with liquid nitrogen.

Liquid nitrogen is sprayed to the alopecia area by freezing, so that the local energy temperature is reduced to-1℃-6℃. Cold stimulation regulates the vasodilation function of skin through nerve conduction, opens closed capillaries, and increases the blood supply of hair follicles, thus improving local nutrition and promoting hair growth.

Another study shows that alopecia is an autoimmune disease, and cryotherapy can change the composition of lymphocyte subsets and enhance immune function, so cryotherapy can improve the immune function of human skin.

Thirdly, liquid nitrogen is a cryogenic liquid with a boiling point of-196℃. After liquid nitrogen is sprayed into the hair loss area, the skin will quickly cool and form a thin layer of cream, which directly kills fungi and mites attached to the skin surface.