@Kootch re Cadaveric Organ Donation:
FWIW2u, brain death must be declared by two physicians, one of whom is a neurologist or neurosurgeon, and the full brain death exams must be performed many hours apart (locally, the timing is at least six hours apart). The patient is then declared legally dead, and the time registered on the Death Certificate is the time of that second exam.
The deceased is registered with the medical examiner's office by the hospital, and family is notified before any work toward donation can occur. Even as a registered donor there is nothing that can be done outside of life-saving work by a hospital until there is a time of death.
It can take MANY hours to perform the tests needed to find blood and tissue type, get med-soc history, receive clearance from the medical examiner's office, and provide the family with the information they need before any surgery can be done. Without recipients located and ready, there is no recovery of organs EXCEPT for kidneys which can remain on a kidney pump pre-transplant for up to 72 hours.
Organs that have suffered anoxic damage cannot be transplanted, hence mechanical management on a ventilator of the deceased until the time of organ recovery. Without the extensive and precise medical/mechanical management, there are no transplantable organs.
For Non-Brain Dead Donation, or Asystolic Donation heart recovery has never yet occured. The process requires that a patient have such compromised respiratory and neurological function that asystole occurs within fewer than 60 minutes after removal of the ventilator.
Withdrawal of mechanical support is the decision made by the family even before the option for organ donation is offered (assuming they haven't asked the hospital about donation already). If the family wants to allow an organ recovery team the chance to be onsite and ready for surgery upon withdrawal, that lengthens the time a family waits after having resigned to the fact that life is no longer possibility. It's a LOT to ask of a family, and even more to WAIT, just for the potential to donate.
Because the timing is so specific, and the anoxic damage that occurs to a body as it shuts down is so great, the organs recovered for transplant are usually only kidneys, and even then (with all tests performed in advance), their suitability for transplant isn't assured until they are recovered. It's just within the last few years that livers have been recovered for transplant from an asystolic donor. the amount of time it takes to perform such delicate surgeries rules out all other organs for potential donation because of the simple process of shutting down. Still, even in these cases, tissue and cornea donation remain an option since these are always cadaveric surgeries.
More info available if desired.
Live well, donate a beautiful corpse.