This girls body is going to have more trauma to it than when she was first placed on the vent.

There's only so much Dopamine to be given before her heart will quit even on the vent. Since the brain is dead the staff has to provide her body with all the hormones/chemicals our bodies need to live. Her body will start failing and there is only so much you can do when there are no neurotransmitters to do the job.

Nine days is a very long time to be dead and on the vent. I think her body is probably already showing signs of breakdown. Maybe if her heart stops the family will accept that, but her date and time of death will still be December 12th.