A few months ago I finally got a portable Inogen Oxygen unit and kept finding the tubing kinked where it comes out of the unit (impeding oxygen flow.) I finally found this little doodad on Amazon which clips to the tubing and shapes it into a curve, preventing it from kinking. I don’t know if I can post links here, so just do a search for this description: Holder for Oxygen Hose,Tubing Strain Reliefs,Tubing Supports for Oxygen Hose (Two cost me $10 US.)
Anyway, just thought I’d share in case anyone else has this pesky problem. At first I was going to try to fashion something out of Duct tape lol but then I came across this.