An update from John this morning:

Usual ritual trying to get up from sleeping with the bi-Pap.  Just trying to sit up in bed causes a breathing attack that I need to recover from.  Oxygen was on 85% through the night but this morning it is back to 100% for a bit due to the activity of getting up.  They will drop the level to 80% once I am in the chair for the day.  I feel the same, not too bad unless I try to move.  Then I just can't breathe and it takes about 10 minutes to recover.  At the moment I'm resting comfortably