@bleo Lung function and oxygen sats are two different things. I am confused at to which of these numbers you stated are what. For example my lung function is 37%, but, my pulse oxometer tells me that my oxygen level is at 91% when I walk, but will also drop to 87% and I am at 96% at sitting rest. So, are you saying that your lung function is at 40% and your oxygen level drops to 37% when you walk? Geeze that is low! No wonder you are struggling. What is your at rest oxygen level on and off oxygen?