Coming out of a coma...?

Ok my stepdad went in for surgery and was supposed to come home the following day but the day after his procedure he stopped breathing which stopped his heart which started again after they shocked him but I guess he had very low blood pressure during and for a long time after and his brain, due to such lack of oxygen is now "permanately' damaged...There is brain activity but its very low and he did open his eyes every so often but they just kinda looked up or rolled around before closing again. He just got put back on a respirator but up until 2 days ago was for the most part breathing on his own. His Dr has only been very positive and optomistic from the start which confuses us because as an example, the day he stopped breathing the dr called saying we can pick him up that afternoon, then 15 minutes later the chaplain called. ANYWAYS...I want to know if there are survivors that were in this same situation and recovered and if the brain can once again function normally. Like I said he does open his eyes every now and then so its not like hes just a vegetable or in a sleeping coma, hes just unresponsive. Also I want to know if theres some type of hypnosis that can be used, a way to guide whatever form of conscienceness hes to Wake up his brain, I hope that makes sense. Thankyou