Will Hyperbaric Chamber Treatment Help A Person Post A Traumatic Injury?

My son was in a auto accident where he flip his car in a canal. They say he was under water (fresh) for 15 to 20 minutes . Water temp was about 80 degrees. He wasn t breathing and had no pulse when pulled from the water. He was revived at the scene and transported to the hospital. Dr s say he has less than 1% chance of recovery to at least a functional life. Yet he looks like he s in there sometimes but in pain. He runs fevers and sweats profusely at tines. The Dr s attribute this to neurological problem. They say his brain can t control these issues. It has been 3 months since the accident and the Dr s want us to consider hospice. A month after the accident, he was able to tract with his eyes and could hear when someone enters the room. None of the neurologist knew this about him. They ran Cat scans and MRIs and EEG s on his brain but said there wasn t significant activity during the EEG test. The Cat Scan and MRI shown no abnormalities. Is there anything else that will be able to help my son. He s only 22 years old and was very athletic. They say that s why they were able to revive him. I ve read about hyperbaric chamber treatments. Is this a possible solution? Any other suggestions would be greatly appreciated.