In adults, the blood volume is about 4.5-5L, when the blood loss is 1L, it means that it is more than 20% of the whole body blood volume, the patient’s appears more obvious shock, but the mental state can be clear, the expression is indifferent, there will be thirst, the skin mucous membrane is pale, the temperature drops, the patient will be cold, the pulse rate is accelerated, the blood pressure is reduced, the systolic pressure is 90mmHg, the diastolic pressure is about 60-70mmHg and Patients have loss of superficial veins throughout the body, collapse, and oliguria. The amount of blood loss is generally judged clinically by the patient’s symptoms and signs, not by how much blood is lost and what happens to the patient. Indicators to determine the amount of blood loss include the patient’s mental status, as well as skin temperature, color of the mucous membranes, eyelids and nail caps, and blood pressure, pulse rate, and urine output.