coma, removed the ventilator... any chance she can survive?

My patient had a cardiac arrest and then went into coma.. Doctors said her brain cells are not functioning properly and there is no much voluntary action... She was on ventilator...
After a week the doctors told that its better to remove ventilator and she will be dead after that within a few minutes.. So we got her home in a ambulance and then removed the ventilator... After removing the ventilator she has survived for almost 7 hours now with normal pulse and hear rate... She hasn't had any fluids, drips or medicine for the past 8 hours... Is there any chance she can survive?? Should we take her back to the hospital or wait for her to die due to lack of food...