A lot of people are not aware of this.
Many countries in the past have taken "cardiac arrest" and "loss of respiration" as the criteria for death. But with advances in medical technology, patients' vital signs such as heartbeat, respiration and blood pressure can be reversed or maintained over time with a range of drugs and advanced equipment. However, if structural damage occurs in the brainstem, no medical treatment can save the patient. Therefore, compared to cardiac death, brain death is a more scientific and reliable criterion.
Brain death is normally determined by 24-hour monitoring. The monitoring program includes the following items: 1) Coma. The response to the whole environment disappears. The following items are monitored: ① Coma, loss of response to the whole environment. Pupils are dilated with no light reflex. (iii) Loss of spontaneous respiration. Including the absence of spontaneous respiration after 3 minutes of cessation of artificial respiration. ④ If not maintained artificially, blood pressure falls sharply. ⑤ Even when stimulation is given, the EEG is linear. The above should be excluded in patients with hypothermia (less than 23°C) and drug abusers. Repeat the above tests in 24 hours and the result can be characterized as brain death.