Nitrous oxide is nitrous oxide. It is an oxidant with the chemical formula of N2O, which can support combustion under certain conditions. It is stable at normal temperature, has slight anesthetic effect and can make people laugh. Laughter is one of the earliest anesthetics used in medical treatment. This is a colorless gas. People can't help laughing after inhaling, which has anesthetic effect. Its anesthetic effect was discovered by British chemist humphry davy in 1799. This gas was used for anesthesia in dental surgery at an early stage. Because of the poor effect of general anesthesia, it is often used with halothane, methoxyhalothane, ether or intravenous general anesthesia. It is used less now. Nitrous oxide (N2O) is used in anesthesia, which has no irritation to respiratory tract and no damage to the functions of heart, lung, liver, kidney and other important organs. There is no biotransformation or degradation in the body, most of them are still excreted with the original medicine, and only a small amount evaporates from the skin without accumulation. It only takes 30 s to 40 s to produce analgesic effect when inhaled into the body. The analgesic effect is strong and the anesthetic effect is weak. The patient was awake (not anesthetized), avoiding the complications of general anesthesia and recovering quickly after operation.