Hi, These conditions do come on in a flash . A year and a half ago I walked up 15 steps from my lower level. My legs melted under me . I went to the ER. Step test , I was 83 . They put me on oxygen and did a cat. Told me I had stage 4 Emphysema. That Fast !! They did a right heart catherisation because it came on so suddenly . It showed no problems . I have been on 24/7 oxygen since . I am on 4 liters day, and 3 liters night . I have a 75 foot line and I move around my house , I am still going up and down , but slower . I am on Trelegy Elipta 200. I also take Musinex 1200 every 12 hours . I have some mucus but not a lot . If I go to the shops I use a cart with a tank . I tried Portable concentrators with pulse “feed” - they aren’t enough for me . The truth is , no portable can deliver over 3 liters per. They are oversold and folks can hurt themselves trying to use them . I am almost 80. I was shocked too. But- The last thing one needs is anxiety. Try very hard to take this event in stride . It is tough to take , but I am 80 hard years old . Blessed Be, I send Peace and love.☮️ Crystal