After cardiac arrest, the ejection of blood from the heart is interrupted and vital organs such as the heart, brain and kidneys will experience anaerobic ischemia. The time to tolerate anaerobic ischemia varies among organs due to different energy reserves. In general, the brain tolerates anaerobic ischemia for 4-6 minutes, the cerebellum for 0-15 minutes, and the medulla oblongata for 25-40 minutes. If there is no quality chest cardiac compression intervention within 4-6 minutes after cardiac arrest, irreversible brain cell death will occur, leading to a decrease in the success of later brain resuscitation.