Beyond this, strict medical tests have to be carried out before brain death can be confirmed. For example, under artificially aided respiration the patient must remain in deep coma for 12 hours without making any independent or involuntary movement. Further tests are needed to verify the patient's inability to breathe alone, and observe for signs of brain activity.
但判定仍須經過一連串嚴格的醫學觀察過程及技術測試，例如在使用人工呼吸器狀況下，病人需連續十二小時持續深度昏迷，且無自發性運動或抽搐，再經測試腦幹功能確定無反射及無法自行呼吸，方可判定腦死。