Most of the shock caused by blood loss is hypovolemic shock, blood loss within 20% of the total blood volume generally does not appear shock, blood loss greater than 30%, more shock phenomenon will occur. Shock is clinically classified into three levels: mild, moderate and severe: 1. Mild shock: blood loss not exceeding 20% will result in a decrease in blood flow to organs that can tolerate ischemia, such as skin, fat, skeletal muscle and bone, and blood is redistributed to vital organs. Patients often show phenomena such as feeling cold, pale skin, wet and cold, flat jugular veins, and concentrated urine; 2. Moderate shock: blood loss accounts for 20%-40% of the total blood volume, and the perfusion of the pancreas, spleen, kidneys and other organs that are poorly tolerant to ischemia decreases, and patients experience pallor, thirst, cyanosis of the lips and extremities, cold extremities, and superficial shortness of breath; 3. Severe shock: blood loss is greater than 40%, when The perfusion of brain and heart decreases, the face is dull, lips and extremities are cyanotic, the extremities are syncopal cold, shortness of breath or tidal breathing, showing compensatory acidosis, diffuse intravascular coagulation (DIC) and multi-organ dysfunction. Patients who experience posthemorrhagic shock should be immediately sought or resuscitated, with intravenous access established and fluid resuscitation performed.