Don't know if it is helpful or not but mum was on oxygen 24/7 about ten years ago. She had a big producer tank in the dining rm and very long tubes that reached all over the house. A service that bought her smaller tanks to use outside the house. But she did get better. I think it was about 3 years she was on it. I thought when she was in the hospital in November and they put her back on that was it again but by the time they moved her to the nursing home it was night only. Then when she was discharged home they followed up with home care but said she no longer needed it. So it is possible he could recover enough to go back to nights only.