The definition of death is divided into: clinical death and biological death.
Clinical death refers to the cessation of heartbeat and breathing; biological death refers to the degeneration and loss of function of all tissues; legal death refers to the failure to respond to all effective resuscitation and rescue efforts.
Since ancient times, people have maintained this concept of death: as long as a person's heart stops beating and spontaneous breathing ceases, he is dead. The concept of the heart as the center that sustains life has guided traditional medicine and law. However, with the development of contemporary medical science and the progress of human civilization, people have gradually changed the definition of death and the standards for determining death.
At present, some Western countries have made society, law, and public opinion accept the concept of brain death.
According to the starting point of irreversible cessation of the functions of three important life organs: the whole brain, heart and lungs, people can divide death into brain death, cardiac death and lung (respiratory) death.
What is brain death? Irreversible loss of function of the entire brain (including the cerebral hemispheres, diencephalon, and brainstem).
The concept of brain death is different from the traditional concept of cardiopulmonary death, where the standard is the cessation of heartbeat and breathing. In a period when medical technology was underdeveloped, patients' brain function and cardiopulmonary function were both impaired. The loss of brain function will cause the loss of heart and lung function; the loss of heart and lung function will also cause the loss of brain function. Modern medicine uses equipment such as respirators and pacemakers. After the patient's brain has irreversibly died, the heart can continue to beat and the lungs can continue to breathe.
This phenomenon of separation of brain function and heart and lung function prompts people to re-understand the concept of death. The essence of death should be that the body's functions as a whole under the control of the central nervous system have permanently disappeared, and its symbol is brain death.
The main criteria for determining brain death are: ① Automatic breathing has stopped, and there is still no spontaneous breathing after artificial respiration for more than 15 minutes and 3 to 5 minutes after stopping artificial respiration. ② Deep coma. He completely lost his response to various external stimuli such as pain and breathing, and had no voluntary movement. ③The brainstem and various reflexes (such as corneal reflex, swallowing reflex, light reflex) disappear. ④ Brain biophone activity disappears and EEG waves are flat. ⑤Cerebral angiography shows that cerebral blood circulation has stopped. Those who meet the above conditions can be declared brain dead after ruling out hypothermia and central nervous system depressant drug poisoning. The direct cause of brain death, in addition to the severe damage to the brain itself, is mostly due to the combined damage of hypoxia and metabolic products (lactic acid, CO2, etc.).
It is ethical and moral to stop all rescue measures for brain-dead people. Modern medicine regards brain death as the only standard of death, making the judgment of death more scientific and making the legal and ethical understanding of death more reasonable. This standard has been accepted by many countries.
What is cardiac death? (Heart death)
China’s past clinical experience has used the criteria for judging death as the heart stopping beating, spontaneous breathing disappearing, and blood pressure reaching zero.
Refers to death primarily caused by irreversible cessation of cardiac function. This is when the heart stops beating before the complete cessation of breathing and brain function. The main cause of cardiac death is severe damage or disease to the heart itself. Other reasons, such as various causes of shock, electric shock through the heart, poisoning with cardiotoxic poisons, etc., can also cause irreversible cessation of cardiac function and death. Neuroreflexive cardiac rhythm disturbances (such as ventricular fibrillation) and cardiac arrest are also examples of cardiac death. The examination of cardiac arrest is relatively easy. Feeling the pulse and the precordial area of ??the left chest with your hands, and listening to the heart sounds with a stethoscope are commonly used simple methods. However, the former is unreliable, and the auscultation examination should last more than 5 minutes. When conditions permit, electrocardiogram examination is the most reliable method.
What is pulmonary death? (Lung dcath)
Also known as respiratory death, it refers to death caused by the lungs or irreversible cessation of respiratory function. The cessation of breathing at this time precedes the complete cessation of heartbeat and brain function. The main causes of pulmonary death are severe injury or disease of the lungs or respiratory system, mechanical asphyxia, poisoning with poisons that hinder respiratory function (such as CO, cyanide, nitrite), and all factors that can cause paralysis of the respiratory center and respiratory muscles. . It is relatively difficult to detect respiratory arrest, especially when the person is in a deep coma and only has weak breathing.
Recommended methods include placing a thin fiber in front of your nose or placing a cup of water on your chest to see if there is any movement of the fiber or the water in the cup.
Other organs such as kidneys, liver, and endocrine glands also play an important role in maintaining life. Severe damage or disease of these organs can also cause death, but in the end it is mainly caused by one of the above three ways. die. The above classification of deaths is completely artificial and arbitrary, and in many cases cannot be accurately distinguished.
Determining the meaning of death
The new definition of death believes that brain death or irreversible coma can be treated equally with death. If a comatose patient is in a persistent state of brain non-function, unresponsive to external stimuli (such as loss of some eye reflexes), and has no spontaneous breathing, muscle movement or brain reflexes, he can be considered dead. At this time, the EEG examination should show no brain waves. The phenomenon of cardiorespiratory arrest (also known as clinical death) refers to: loss of consciousness, cessation of breathing, disappearance of heartbeat and pulse, and dilated pupils.
The determination of the concept of death or the definition of death is of great significance in medicine and law. Declaring a person dead means that all rescue measures can be legally removed; it means that the body (corpse) can be medically or forensically dissected, cremated or buried; and useful organs and tissues can be used. The purpose of transplantation means that he is relieved of all criminal liability; it also means that he can start the inheritance of his property. For forensic medicine, the determination of death can also be used to determine the time of death, which is of great significance for narrowing the scope of investigation and determining guilt and innocence.