To elaborate, it could be valuable to look into the therapeutic intent of providing higher oxygen levels.

A couple that come to mind would be when someone's lungs aren't working the best so they can't go through as much volume, in that case perhaps they could get more oxygen with less breathing when the air has an ideal saturated content?

The other is, I have heard they do this for burn victims who are having a lot of cell death, I am not sure if that is fully agreed upon though. This latter case probably falls outside the scope of physiotherapy into surgical medicine though so I am guessing the former could be more relevant?