I'm going to ask my doctor and see if He has an answer. It happens every day and I really want to know if it is co2 buildup. I will post my answer from my doctor on this thread. I am sorry you are going through it, but relieved that I am not alone. How long have you had COPD and are you on oxygen? I am 24/7! I manage well, though gotten quite used to it; have a great portable that lets me get out with friends etc.