How to define "death" in medicine?

Death is the disappearance of people's essential characteristics. This is the transition from birth to death. Death is not the sudden end of life, but a process of continuous progress, a process from quantitative change to qualitative change.

Sociology divides death into three periods: social death, knowledge death and biological death. Medicine divides death into three periods: near-death period, clinical death period and biological death period. Death in medical ethics is equivalent to the biological death period of sociologists and the clinical death period of medicine.

The characteristics of the three stages of medical death are as follows:

1, dying (dying)

It is the loss or deep inhibition of the nerve center function above the brain stem, while the nerve function below the brain stem still exists, but it is in a state of disorder due to the loss of control over the upper central nerve. The patient has unconsciousness, circulatory failure, respiratory failure, metabolic disorder, various reflexes and loss of muscle tension.

2. Clinical death period

It is a state of deep depression and loss of function outside the medulla oblongata, so various reflexes disappear and breathing and heartbeat stop.

3. Biological death period

Is the last stage of the death process. At this time, the metabolism of the whole nervous system and other organ systems stopped one after another from the cerebral cortex, and the whole body changed irreversibly and could not be revived, but individual tissues could still have minimal metabolic activities for a certain period of time.

Regarding the standard of death, the medical community has always regarded breathing and cardiac arrest as the only standard of death, and cardiopulmonary function as the most essential feature of life. Modern medical research shows that death is a continuous process. Since the forties of this century, due to the wide application of medical engineering technology and the continuous improvement of resuscitation, people who have stopped heartbeat and breathing can still be resuscitated. Patients with extensive brain cell necrosis can still maintain their heartbeat and breathing for a long time because of the application of artificial respiration machine; But once the ventilator is removed, breathing and heartbeat will stop immediately. The above shows that the cessation of cardiopulmonary function does not necessarily mean death, and the dependence of cardiopulmonary function on manual maintenance does not mean the continued existence of life, which makes the traditional death standard face new challenges.

Because brain death is irreversible, some scholars put forward that brain function loss is the standard of death. At the 22nd World Medical Association held in 1968, "irreversible loss of brain function" was put forward as the diagnostic standard of death. Since then, the United States has also formulated four criteria of Harvard brain death and the definition of death.

The diagnostic criteria of brain death developed from the medical point of view replaced the traditional concept of death.

There are four criteria for brain death:

(1) The body is slow to respond to various stimuli;

(2) the body's spontaneous movement and spontaneous breathing disappear;

(3) All kinds of reflections disappear;

(4) The brain waves are flat.

Brain death is irreversible, which has been accepted by more and more people as a more superior and scientific criterion than the traditional standard. However, the traditional concept of death still has its influence, so some people put forward the idea of combining the two to make it more comprehensive and realistic. That is, a person's circulatory and respiratory functions stop irreversibly; Or the irreversible stop of all functions of the whole brain, including the brain stem, is death.