The three pathophysiologic phases of shock are the microcirculatory ischemic phase, the microcirculatory stasis phase, and the microcirculatory failure phase. The microcirculatory ischemic phase is the early stage of shock, in which blood perfusion in the microcirculation is reduced and the tissues start to become ischemic and hypoxic, so it is also called the ischemic hypoxic phase. At this time, the contraction of small blood vessels throughout the body occurs, especially the pre-capillary resistance vascular contraction is more obvious, and the perfusion in this period is characterized by less perfusion and less flow, less perfusion than flow, and the tissues are ischemic and hypoxic. Microcirculatory stasis period is also called shock progression period, at this time the blood flow rate slows down significantly, the tissue perfusion flow is further reduced, and the hypoxia is more serious. The microcirculatory perfusion in this period is characterized by perfusion but less flow, and the tissues show a stagnant hypoxic state. The period of microcirculatory failure is also called the refractory period or DIC period, when the microcirculation is even more severe and shock is difficult to correct.