I have copd. what can cause me to have a great oxygen level when lying still, but have it go down when active? more active i am, the lower it goes.

Empysema: I would hope that your physician has taught you some about copd. COPD is a lung disease that makes it harder to exchange carbon dioxide and oxygen in the lungs. When you are still you have a minimal oxygen requirement. But as you exert yourself to doing activities your heart rate goes up and your ability to oxygenate your blood well enough goes down. This is the crux of your disease.

Activity: In some patients with copd, the lungs can't supply enough oxygen to keep the oxygen level (saturation) normal. This may happen with activity when the body starts to use up its oxygen supply. If you rest, you can catch up and get back to normal. However, you may need oxygen at this point. There are specific criteria to qualify, so talk to your family doctor or lung specialist.