Our bodies need a certain amount of oxygen molecules circulating in the bloodstream at all times. When all internal organs are functioning correctly, the oxygen that you inhale passes from the tiny alveoli or air sacs of your lungs into the bloodstream, and the pumping action of your heart delivers this oxygenated blood to all parts of your body. The other 79% of each breath is simply exhaled without being absorbed by your lungs.
If your lungs aren’t working at their full capacity, they are likely unable to take in the full amount of oxygen that each breath would normally supply. Insufficient oxygen can result in a condition called “hypoxia” or “hypoxemia.”
Your doctor, if they haven’t already, will likely measure your blood oxygen levels using an oximeter or by taking a blood sample. A blood sample is most common in first-time oxygen users as this test measures more than just dissolved oxygen; it also provides a reading on the level of carbon dioxide in your blood as well as your blood’s PH level. These additional indicators provide your doctor with a complete picture of your body’s overall oxygen supply and health.