progression of the illness

Last year my husband tested just at the cut-off for late stage COPD. I was made aware recently that his sats drop into the mid-high 80s when he moves around, even with oxygen on. He also has shown some cognitive deterioration in the last 6-12 months. Recently his diuretic dosage was upped due to swelling in his lower legs. Can I assume this is all an expected progression of his illness?