Coma and ‘brain death’

At one time doctors were able to pronounce a patient dead on the absence of the vital life signs. Since the 1960s, there has been a rapid growth of life-support technology, including ventilators and intensive care units. This has meant that individuals can now be sustained almost indefinitely, even when in an irreversible coma brought about by, e.g., massive head injuries or through poisoning by a drug overdose.

With the advent of organ transplantation programmes, doctors found themselves caught in an uneasy situation. They could be legally held guilty of manslaughter, through medical negligence, if they decided to switch off the life-support equipment of patients they believed to be suffering from irreversible brain damage. Thus new criteria for the determination of death had to be drawn up. Most countries now accept that cerebral death and brain-stem death are reasons to switch off life-support machines. Cerebral death is usually determined via electroencephalograph (EEG) measurements. A flat electrical trace showing no brain activity is clear evidence that death has occurred, even though the heart may still beat and breathing can still be continued with the aid of a ventilator. Some doctors may also require an arteriogram to be performed, examining the flow of blood within the brain. Massive haemorrhages that have certainly irreversibly damaged the brain can be located in this way.

Recognition of these new criteria of death has made it much clearer for doctors to know where the limits for sustaining life lie. It has also made the task of parting with a hopelessly brain-damaged person easier for relatives, whose grief could otherwise be drawn out over months if not years.

Such procedures however, are not invariably used to determine whether or not death has occurred. In the vast majority of cases death is all too obvious and the individual’s dignity is preserved by a simple clinical diagnosis.