However, there have been some very long-term survivals and it is noteworthy that expert management can maintain the bodily functions of pregnant brain dead women for long enough to bring them to term. Criticism
The diagnostic criteria were originally published for the purpose of identifying a clinical state associated with a fatal prognosis (see above). The change of use, in the UK, to criteria for the diagnosis of death itself was protested immediately. The initial basis for the change of use was the claim that satisfaction of the criteria sufficed for the diagnosis of the death of the brain as a whole, despite the persistence of demonstrable activity in parts of the brain. In 1995, that claim was abandoned and the diagnosis of death (acceptable for legal purposes in the UK in the context of organ procurement for transplantation) by the specified testing of brainstem functions was based on a new definition of death – the permanent loss of the capacity for consciousness and spontaneous breathing. There are doubts that this concept is generally understood and accepted and that the specified testing is stringent enough to determine that state. It is, however, associated with substantial risk of exacerbating the brain damage and even causing the death of the apparently dying patient so tested (see "the apnoea test" above). This raises ethical problems which seem not to have been addressed.
This test – the apnoea test – is dangerous, and may prove lethal.Two doctors, of specified status and experience, are required to act together to diagnose death on these criteria and the tests must be repeated after "a short period of time ... to allow return of the patients arterial blood gases and baseline parameters to the pre-test state". These criteria for the diagnosis of death are not applicable to infants below the age of two months. Prognosis and management
With due regard for the cause of the coma, and the rapidity of its onset, testing for the purpose of diagnosing death on brainstem death grounds may be delayed beyond the stage where brainstem reflexes may be absent only temporarily – because the cerebral blood flow is inadequate to support synaptic function, although there is still sufficient blood flow to keep brain cells alive and capable of recovery. There has recently been renewed interest in the possibility of neuronal protection during this phase by use of moderate hypothermia and by correction of the neuroendocrine abnormalities commonly seen in this early stage.Published studies of patients meeting the criteria for brainstem death or whole brain death – the American standard which includes brainstem death diagnosed by similar means – record that even if ventilation is continued after diagnosis, the heart stops beating within only a few hours or days.