I have a set of fold up luggage wheels (about $15, Walmart, Kmart, Academy Sports...) for my vest bag (I have a Hillrom 104), and I just put my other carry on bag on top of it- there is no way I can carry that thing all through the airport <img src="i/expressions/face-icon-small-wink.gif" border="0"> .
When I go through the security check point, I do have to take it off the cart and run them through the machine seperately.
They usually open my bag and look and "sniff" my machine with the wand, and when they ask what it is, I tell them it is a "Medical Compressor", and I carry the books and stuff that came with it just in case someone wants a more in depth explanation. If someone is acting a little rough with it, I inform them that it is a <b>$16,000 </b>medical compressor <img src="i/expressions/face-icon-small-wink.gif" border="0"> .
I've only had one flight that was a issue at all with it, and that was because they changed our plane to a smaller plane with smaller overhead bins than scheduled, and they had to put my vest up front with the stewards(I had called ahead of time to make sure everything was fine since it was the first time I flew with it, and they also stranded us in NC over night. This airline is now out of business, lol).
It's a bit of a pain, but not as much as I expected. I would really like to get the bag with the built in wheels, but it's $75. For $75, I'll take a little extra hassle with my luggage wheels a couple of times a year.
I hope you have a good time <img src="i/expressions/face-icon-small-smile.gif" border="0"> !