Nitrogen used in medical surgery

There are two possibilities, one is used for frozen anesthesia, the theory is that the temperature of liquid nitrogen is very low, can be used for anesthesia, that is, to absorb a large amount of heat so that the patient's body temperature is lowered, so as to achieve the purpose of anesthesia, and the other possibility is that that sheet is written on the wrong, originally wanted to write the ability to be nitrous oxide, or called nitrous oxide, a substance also known as nitrous oxide, there is a certain anesthetic effect, can be used as an anesthetic.