Oxygen inhalation by mask, also called oxygen inhalation by mouth-nose mask, is to put the mask over the whole mouth and nose, so that you can breathe through the nose and mouth. 1. The mouth and nose are in a relatively closed environment, the concentration of oxygen inhalation is relatively stable, and the irritation to the respiratory mucosa is relatively small, which is more comfortable than oxygen inhalation by nasal catheter, but you need to remove the mask when eating. 2. The position of the catheter, as well as the structure of the nasal cavity and breathing conditions, can affect the amount of oxygen inhaled. The air flow is also more irritating to the nasal mucosa, and the comfort level is not as good as that of the mask.