The body does not store oxygen. Supplemental O 2 is a drug. Supplemental O 2 is the most commonly-prescribed drug in hospitals. A reduced PaO 2 is a non-specific finding. High FIO 2 doesn't affect COPD hypoxic drive.
Oxygen masks migrate.
SaO 2 is simply the percentage of available binding sites on hemoglobin that are bound with oxygen in arterial blood. However, SaO 2 unaffected by the content of hemoglobin, so anemia does not affect SaO 2 . CaO 2 is arterial oxygen content. PaO 2 is a sensitive and non-specific indicator of the lungs' ability to exchange gases with the atmosphere. FIO 2 is the same at all altitudes.