I was diagnosed with COPD (emphysema) in 2000. I went on oxygen just at night a couple of years later. I got invasive aspergillosis in my lungs and cellulitis and sepsis in my legs. I was really sick. I was in and out of the hospital and then rehab in a nursing home. I think it was in 2019 that they sent me home with oxygen 24/7. I think it must have around that time that they put on Trelegy. For me it was a miracle. I stopped having crashes and trips to the hospitals. I have been the hospital one time since 2019 and then only 2 nights. Your emphysema must have been much worse than mine when you diagnosed to have started on oxygen that quick. Right now I am on 2 Ltr when just sitting and 3=when moving around. I now have a lot of trouble breathing when I walk. I use a walker just to carry my purse and portable oxygen. I can walk fine but if I carry things i have much more trouble breathing. I have done Pulumary rehab for years. They say that will help keep your lungs expanded but I think as my disease progresses. nothing is going to stop it from getting bad. I wish you well. I think what makes me the most upset is the fact I caused this myself. Best of luck and as to oxygen level I have 4 oxymeters and they all read different so mine runs between 86 to 92. P