Circulatory failure usually refers to a decrease in the effective circulating blood volume in the body due to various reasons, because tissue oxygenation relies on red blood cells to carry oxygen, and a decrease in the effective circulating blood volume triggers a decrease in the oxygen-carrying capacity of red blood cells. It also leads to inadequate perfusion of tissues, which in turn leads to metabolic disorders. These can be divided into those with inadequate perfusion of the tissues due to cardiac pump failure, and those with inadequate or relatively inadequate blood volume due to other etiologies. For cardiogenic causes it is usually common to see a variety of severe cardiomyopathies, myocardial ischemia, injury, or even acute coronary syndromes that trigger cardiogenic shock. Some patients are in shock due to blood loss, massive fluid loss, or even severe trauma, infection, and allergy, which cause peripheral vasodilatation.