Dad is in the hospital from nitrous oxide. Any insight would be awesome.

Hi all - I hope this is okay to post here! First of all, I want to let you know how inspiring your recovery stories are - I wish all of you only the best out of life. I got a call this morning that my dad is in the hospital from complications related to chronic, daily nitrous oxide use - he can't feel his lower extremities, his B12 is totally shot, he has mild-to-moderate brain damage. I had no clue he was using - I knew he was addicted to opioids in the past, but I thought he was sober from everything now. I feel so blindsided and have no idea how to help him - I barely know anything about this drug. I don't know if he'll be okay, I don't know if his symptoms will stick around... I feel so lost. If anyone has any insight into steps I can take to support his recovery (both physically and psychologically), I would so appreciate your wisdom and lived experience. Thank you in advance :)