When a person is dying, there will be systematic symptoms such as: 1. The digestive system will have frequent nausea, vomiting, inability to eat, poor appetite, accompanied by severe diarrhea, or even watery stools, mucus, pus and blood, etc. 2. The circulatory system will have cardiac failure, inability to breathe normally, sedentary respiration, and the apparent appearance of, for example, tachycardia or bradyarrhythmia alternating with tachycardia, etc. 3. The respiratory system will have a significant decrease in blood Oxygen saturation is reduced, and it is difficult to correct hypoxemia, there will be an increase in the partial pressure of carbon dioxide, no matter how much the concentration of oxygen inhalation, the partial pressure of oxygen can not be raised the situation indicates that there are symptoms of respiratory failure. 4, the nervous system will have a series of near-death symptoms, such as delirium, coma, and unconsciousness.