The brain is the organ with the greatest demand for oxygen among all organs of the human body, and the oxygen consumption of the brain accounts for 20%-30% of the total oxygen consumption of the human body. Therefore, when anoxic coma occurs, brain cells start to die in a very short period of time, and the tolerance limit of brain cells to anoxia at room temperature is usually 4 minutes. If this time is exceeded, brain cells will undergo irreversible necrosis and their functions cannot be restored. Therefore, the optimal time for waking up from hypoxic coma is within 4 minutes, of course, the shorter the time, the better the effect on the recovery of brain cells, if the longer the time, the more likely to leave sequelae.