Nitrogen is a medical gas used for cryosurgery removal of some cancers and skin lesions, and also for the storage of tissues, cells, and blood in cryogenic temperatures to avoid oxidation of the samples. It can also be used as part of the medical gas mixture for lung function tests. The pharmaceutical industry uses this medical gas in the manufacture of medications.
Nitrogen as a gas is used to power tools in places where they do not have instrument air. Most of the time it comes from a manifold of cylinders and is piped at pressure with an alarm system at the source and on the use site.
Liquid nitrogen is a couple hundred degrees below zero and freezes tissue on contact. So it could be used in a procedure room (to take off warts, etc) or to freeze tissue samples, but it usually would not be in an OR.. Plus, it comes in gigantically insulated pressurized bottles so it does not evaporate.
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