I was recently diagnosed with emphysema based on a CT scan. My pft results are in the low normal range. However, I have progressive muscle weakness, weight loss, shortness of breath and my o2 saturation drops below 90% for several seconds upon exertion. I also may have some desaturation at night based on a home sleep study. Until a few months ago I was exercising 30 minutes 5 times a week and felt fine. Does anyone have any ideas what might be going on? It doesn't seem like I should be having these symptoms with low normal pft results.