Cerebral perfusion decreases as the intracranial pressure is raised.Irreversible ischemic change occurs when cerebral perfusion pressure is below 40 mmHg.

• 颅内高压发生时相对的脑灌流压下降，脑部的循环便受到影响，当颅内高压无法控制而脑灌流持续低于四十毫米汞柱时脑部终至缺血而死。