I googled it and it just means your asthma is unstable.
there are only a limited amount of asthma meds available. They put you on predisone to stabilize you.
but predisone is a catch 22 drug. it saves your life and it also can kill you...make sure you taper the drug, don't go off it all at once. and also, sometimes it takes longer to taper the lower you get. if you taper too fast you can rebound.
When it comes to tapering, listen to your body, not your doctor. Doctors want to get everyone off the drug fast. some don't tolerate a fast taper. Be sure to keep in touch with your doctor while you taper, because it is a life and death situation.... so if you have to taper more slower than the doctor originally said, that is fine...take your time. your body will tell you what you can handle and how fast.