Not enough coffee yet this morning. I read the thread title and the couple of posts thinking the second letter in CPAP was an R!
There is ribbed knit tubing widely available that would work for this purpose. All you would do is cut off a length and slip it over the hose. You can probably find it in a well-stocked pharmacy in the area of the bandages. Here is a link to it on Amazon:
http://www.amazon.com/Stockinette-Kn.../dp/B001B5M330
It is very stretchy and one use for it, I think, is to cover casts.
This type of stockinette comes in different sizes and strengths. There is a compression version, for example, that might be more stable for your purpose.