脑死亡的临床诊断标准在某些国家已建立，但在放弃生命支持治疗时仍需辅助检查对临床脑死亡的诊断加以确认。有效脑血流的停止是脑死亡的一项客观依据，因此脑血管造影被认为是诊断脑死亡的金指标，但在临床应用上常有很大困难。TCD是近十几年发展起来的一种无创伤性检查脑循环 Clinical diagnostic criteria for brain death have been established in some countries, but the need for laboratory examinations to confirm the diagnosis of clinical brain death is still awaited when life-support treatment is discontinued. Effective cessation of cerebral blood flow is an objective basis for brain death, cerebral angiography is considered to be a gold index in the diagnosis of brain death, but in clinical practice is often very difficult. TCD is a noninvasive examination of the cerebral circulation developed in recent ten years