I'm not certain about how long, but my Dad's vitals were good right up to the day before he passed. He lost the ability to swallow and couldn't drink. It was a Wednesday when he spit out everything saying he couldn't swallow. I tried to give him liquids with a dropper but it would just gurgle at the back of his throat. He went to sleep for the last time that Saturday and it took him until Thursday morning around 8:30 to pass away. The day before he had a bed bath and the aide took his vitals and they were all still good. I was told they can be good right up to the end. That morning he was unresponsive and breathing heavy. The rattle he had the night before wasn't very loud so I was unsure if it even was a death rattle. That morning his breathing was clear but hard and fast. I called the nurse and she was coming to see him. I sent everyone to school/work promising to call them if the nurse said it was time. I really didn't know how long that was going to go on. I really didn't know that was the end. He died after everyone else left and before the nurse came. I was making beds and starting my normal morning routine. I went to check on him and there was no mistake by the look that his light was gone. My heart goes out to yours along with my prayers. I know it's hard the waiting and watching. She may go when you least expect it. Hugs and prayers to you.