Hi Tina. I believe the trick to figuring out if one needs oxygen supplementation (besides talking to your dr), is to test the oxygen level while walking for 6 minutes with your pulse oxometer. If C02 falls below 88, and the heart rate goes higher, then it is time to ask your dr if it is time to go on oxygen. I am ok when I am seated to watch tv or eat a meal, but as soon as I get up and walk any amount; my C02 levels drop drastically. I reported this to my dr and was prescribed oxygen 24/7, basically. Remember, you cannot go strictly by what the c02 sats are, but also need to keep on eye on heart rate. Higher heartrate can indicate that the heart is compensating for the lungs. It beats faster to supply the lungs with additional oxygen. I hope this helps.