Dear Student,
Some gases which are used in hospitals are described below :
Oxygen : Oxygen is used in hospital for the patients facing difficulty in inhaling atmospheric oxygen. It is used in resuscitation and inhalation therapy.
Nitrogen : Nitrogen is used in crysurgery, storage of tissues , skin lessions and storage of blood in cryogenic situation.
Carbon dioxide : Carbon dioxide gas is used in insuflating surgery like laproscopy, arthroscopy and for respiration stimulation.
Regards