Sudden cardiac death, cardiac arrest

My father in law had a cardiac arrest in the ambulance while on the way to the hospital. The ambulance was called because he was feeling short in breath. He entered the hospital as pulseless electrical patient and was resuscitated at the hospital. They gave him sedation and put him on dialysis, ventilator and hibernation. After 48 hours he was eased off the sedation and brought back to normal temperature. Since then, the heart did not have any more problems and the brain functions seems back to normal but he is not waking up. He is not in a coma since he answers to light stimuli, blink his eyes and moves his right foot, but do not respond to pain stimuli.  If his heart and brain are ok, why he doesn’t wake up? Thank you