question: is my dad brain dead so to speak? just had a cows valve placed ,not sure where in his heart ........surgery w/o complications, he s 72, diabetic,low blood pressure , etc.......just saw him, on ventilator and understand that this could be for a few days up to weeks........nurse stated they did wake him up very briefly for a minute as we were very concerned due to them having a very difficult time many years ago (robotic prostrate cancer operation)thank you