This is certainly false, and a lot of that comment is completely incoherent.
Per the original Harvard Med rules, brain death for beating-heart donors couldn't even be declared without 24 hours of ventilated observation of the patient.
Per DCI Donor Services (a large organ donation org), brain-dead patients today are regularly ventilators for several days while maintaining transplant-worthy status. The minimum turnaround for a donor is about 12 hours from brain death, since a full disease screen takes around 8 hours. And the maximum turnaround time after removal for even the shortest-lived organs like lungs is 4+ hours.
Possibly the commenter is trying to say that patients who enter unventilated brain death will cease to be viable donors within two hours? But that position is even more incoherent; the problem with unventilated brain death is that it promptly becomes cardiac death also.
That's only possible in cases of very limited braindead. "Mostly" a braindead person will have a slowly lowering heartbeat, and once it hits 20 or so, they die. This usually takes hours, not days.
Now, there's a gazillion different ways to be braindead. It can be that the spine is disconnected somewhere (in fact this is the most common reason, thank you traffic), and on the other end there is no sharp cutoff between braindead and in coma, where we see no damage whatsoever and can even be brought on by a normally unrelated disease (but often some form of poisoning is suspected). Therefore there can be very weird phenomena in a significant number of cases. Also the symptoms depend on the exact point the disconnection occurs. If it's deep in your back (10th vertebra or lower), you're dead in minutes, unless it's very, very deep (18+).
But mostly, you don't survive braindead for very long. Even an artifical "braindead" state (which is what barbiturate overdose patients die from) normally doesn't last more than 3-4 hours before death occurs, including the period where activity slows (so starting from the point the overdose was administered).
Per the original Harvard Med rules, brain death for beating-heart donors couldn't even be declared without 24 hours of ventilated observation of the patient.
Per DCI Donor Services (a large organ donation org), brain-dead patients today are regularly ventilators for several days while maintaining transplant-worthy status. The minimum turnaround for a donor is about 12 hours from brain death, since a full disease screen takes around 8 hours. And the maximum turnaround time after removal for even the shortest-lived organs like lungs is 4+ hours.
Possibly the commenter is trying to say that patients who enter unventilated brain death will cease to be viable donors within two hours? But that position is even more incoherent; the problem with unventilated brain death is that it promptly becomes cardiac death also.