I presently use a portable oxygen concentrator Inogen G-4 which is set for 3 liters which is what I use.My large oxygen concentrator works fine on this setting it of course is continuall flow.Pulse flow is not the same when I go out with my portable oxygen set on 3litters my oxygen level never gets up to a decent level I am always breathing very hard with it.I wanted to know if I bought a InogenG-5 and had it set all the way to 6 when it help me breath better