Death - the end of life?

DEATH is an irreversible process and whilst doctors find it convenient to pronounce it as occurring at a specific time, it is not an event “at a moment in time”. Death occurs when oxygen delivery to the body’s tissues fails. Some organs have tissues that are more sensitive than others to oxygen deprivation. Therefore when a person dies, the organs in his body die at different rates. There are however some organs where death will immediately spell the end of life for the human body. These are the organs responsible for the delivery of oxygen to the tissues. The integrity of the respiratory system and cardiovascular system is essential for the survival of the human body as these two systems are totally responsible, together with the haematological system, in carrying oxygen to the tissues.

TRADITIONAL DEFINITION OF DEATH Traditionally, death is recognised to have occurred when these two systems are no longer intact. When the patient stops breathing and the heart stops beating, oxygen delivery to the tissues for the process of living fails. With modern technology, however, we are able to take over the function of these two organs and the patient can seemingly be kept “alive”.

BRAIN STEM DEATH It must however not be forgotten that even when technology can take over the function of these two systems, the nervous control in the brain of these two organs (more so the cardiovascular) must be intact for the body to continue living. The control lies in the brain stem and if the brain stem is dead as a result of oxygen deprivation, the output of the heart cannot be sustained pharmacologically or mechanically indefinitely. Any attempt to try to support the cardiovascular system in the face of brain stem death usually ends with failure. Evidence has shown that, when a patient has brain stem death, the cardiovascular system, even when supported, fails in a few days or at the maximum a week or two. Therefore the integrity of the brain stem is essential for life and if this is dead, a patient is considered to have suffered death because there is no way he can carry on living even when the organs responsible for delivering oxygen to the tissues are seemingly alive whilst being supported mechanically. In the presence of technological support, death can be a prolonged process. If the cardiovascular and respiratory systems are supported, the traditional method of diagnosing death will not immediately prevail. Under these circumstances, diagnosing brain stem death as soon as it occurs would be the more logical approach.

DIAGNOSING BRAIN DEATH To make a diagnosis of brain stem death or occasionally described as brain death, one has to ensure that the brain stem functions are all no longer present. As all the cranial nerves are housed in the brain stem, integrity of the cranial nerves are tested for integrity of brain stem functions by two experts (anaesthesiologists, intensivists, neurologists, neurosurgeons or paediatricians, with at least five years of training) at two different time intervals. Besides that they must also exclude other causes that can bring about similar manifestations and all these are formally tested together as brain death testing.

OPTIONS AFTER DIAGNOSING BRAIN DEATH Brain death testing, if done as soon as there is evidence to suggest brain stem death, reduces the time lapse between death and the pronouncement of death. As mentioned, even if nothing is done, the time interval between brain stem death and traditional evidence of death in the form of cessation of heart beat is usually a few days and up to two weeks. Brain death testing allows the dying process to be shortened for the benefit of the family. When such a major event has occurred, intensivists are likely to have discussed with family members the options available to them. One option would be to remove support immediately after the diagnosis has been made. This must be handled with sensitivity and not all doctors are well- trained to handle this situation. The other option would be to continue support, not in intensive care, but in the wards where death seen in the traditional manner would follow its course.

Brain death testing would also allow the early harvest of useful organs from the body whilst these organs have not suffered the process of death. It is important to realise that doctors who are responsible in making the diagnosis of brain stem or brain death have a heavy responsibility towards the patient. To avoid conflict of interests or misunderstanding of their roles, these doctors should avoid having simultaneous responsibilities in harvesting organs from the patient concerned or be involved in managing any of the recipients of organ transplant. Whilst all these knowledge and skills are available to us, some doctors may not push for brain stem testing for all patients who are brain dead. Under that situation, we are exercising the option of allowing the patient to die a traditional death. When we do that, we not only prolong death, we may be depriving more deserving patients of the bed in the intensive care unit (ICU) if we do not make arrangements for transferring the patient out of ICU. It is difficult to generalise what takes place in this country. It is believed all options are exercised and doctors and family members probably end up choosing a path they are comfortable with. [BY Prof Dr CHAN YOO KUEN]