How long does brain death last?

Brain death is the irreversible loss of all brain functions, including the brainstem, which may soon manifest itself as respiratory and cardiac arrest, since the brainstem is where the respiratory and cardiac centers are located. Brainstem dysfunction, heartbeat, breathing may be terminated, but at present due to the progress of rescue equipment or medical instruments and drugs, the patient's breathing, heartbeat may still be able to maintain for a period of time, for example, even if the patient has brain death, but the patient's breathing can still be maintained with a ventilator inserted, no spontaneous breathing, peripheral breathing with a ventilator to maintain oxygenation, if the heartbeat is not good, with a cardiac pacemaker or drugs can also maintain the patient's heartbeat. This situation may continue for some time, but it is no longer meaningful to maintain it.