Suggest Treatment For Difficulty Breathing In A Coma Patient

Hi, I have a friend who was addmitted to hospital wilth pneumonia type symptons nealy three weeks ago. She was put into a coma two days later. Test results have failed to come up with a diagnosis. She is now breathng 60% for herself, but still on a breathing machine. Three days ago they stopped the medication, but she has still not come out of the coma. We are very worried as we were told that she would probably waken within 48 hours. Could there be any brain damage if she takes much longer to come around?