The same thing happened to me, what happens is that while having stomach surgery, its makes it harder to brethe in and out fully so in my case parts of my lungs were collapsing, but I felt better after using my spirameter? I think thats how its spelled....but use it! It works! At least 10 x an hour, use a pillow and press against your stomach when you need to cough, when you brethe in hold it for a second or two, it needs to open up your so called " grapes" in your lungs.