晕厥又称昏厥、昏倒等，是由于急性广泛性脑供血不足而突然发生的短暂的意识丧失状态。发生晕厥的原因很多，大致可分为四类：第一类是血管舒缩障碍，其中主要是血管抑制性晕厥和直立性低血压所致的晕厥；第二类是心源性晕厥；第三类是脑源性晕厥；第四类是血液成分的异常。血 Syncope, also known as syncope, fainting, etc., is due to acute extensive brain shortness of sudden and sudden loss of state of consciousness. There are many reasons for syncope, can be divided into four categories: The first is the vasomotor disorders, which are mainly due to vasomotor syncope and orthostatic hypotension syncope; the second is cardiogenic syncope; the third Class is brain-derived syncope; the fourth category is abnormal blood components. blood