Please read this important disclaimer. So you've got a busy week ahead of you. Maybe you and your mother or father can work as a team. See the site below for your rights as a new york state hospital patient. If she was not in a wheelchair when she was admitted she should be out of bed periodically and walking.
Hospitals get the patient out of bed and walking the day after heart surgery.
If your grandmother was breathing on her own before she entered the hospital she should be breathing on her own when she gets out. The hospital caused the need for the vent and they should be reminded of this from the nurses, on up to the doctors and hospital director. The nurses don't really want to cover for the doctors anyway and should be reminded that they are not technically not allowed to. Massachusetts general hospital may be willing to work with you on noninvasive nasal mask if you get nowhere in new york state. You do have the right to direct your own health care and if you request BiPAP mask in writing you should be able to get it if she can tolerate it.