What does it feel like being in advanced stages of emphysema?

Under water: One of my patients once described emphysema as being similar to being underwater and not being able to come up for air - probably very accurate.

Shortness of breath: Usually, the advanced stages of emphysema are associated with shortness of breath, even at rest. Sometimes cough, chest tightness, wheezing. Many times people require oxygen. It is quite uncomfortable. I hope you never reach that stage.