I was in a very similar situation as your father. I did not know where I was, what year it was, where I was or even the faces of visitors. At one point the Dr. told my wife I would be dead in as little as 10 minutes. I remember opening my eyes though and seeing my wife stroking my hair, I told her to quit stroking me, it was annoying and she started to laugh and cry at the same time. Yes I have liver damage and brain damage but I am back to my basic self. How much difference it made seeing my wife I'll never be sure, but just having contact with her seemed to be the most important thing in the world.

I would suggest that sending your dad a family photograph with the names written on the back so the nurses could help him remember who everyone is. Plus having the picture would bring a smile to his face. Add to that your phone calls and you will have helped him greatly.