Sparing on the lung bases?

What does "Sparing on the lung bases" mean? The only thing I can find on sparing is that it means crystalizing. I have extensive emphysema of the mid and upper lungs. If sparing does mean crystalizing then what does all of this mean and how bad is this condition? What do I have to look forward to on other conditions developing like cancer? I also have G.E.R.D,Fibromyalgia & Chronic Fatigue Syndrome and I am Hypoglycemic and have put on a lot of weight in the past few months and don't know why!

[National Jewish]

The word "sparing" is most often found in chest X-ray reports and it refers to the non-involvement of part of one or both lungs, by a disease process that is present in the remainder of the lungs. The "spared" part is presumably a portion of still-normal lung. The most common form of emphysema, spares the bases, which sounds like the description you have provided.

[jodi8]

A related discussion, bad air was started.