I had bad pneumonia and was in hospital for over 5 weeks during Dec/Jan. My sat levels where averaging 88 and after much debate I was sent home with oxygen. I used it regularly when I came home and then felt that I needed it less and less and haven`t used it now at all for 3 weeks. Is your sat levels something that might get better if you have had lung truama? I`m not not sure if I should be using it regularly regardless. On a recent visit to the doctors I mentioned it to the nurse and thought she would test my sats but looked at my nails and said that she could tell by the pink colour in them that my sats looked ok and not to worry. I don`t see my consultant until July but I guess he can put me more in the picture.