Central venous pressure refers to the pressure in the superior vena cava, inferior vena cava and the right atrium of the human body. By measuring the central venous pressure value, the effective circulating blood volume in the patient’s body, the function of the right heart and the vascular tone can be detected. 1. Circulating blood volume: the normal value of central venous pressure is usually 5 to 12 centimeters of water column. If the value of central venous pressure is lower than 5 centimeters of water column, then it is considered that there is low blood pressure and insufficient blood volume, and then it is necessary to replenish the colloid and crystalloid fluids in time. 2. Function of the right heart and vascular tone: If the value of central venous pressure is higher than 12 centimeters water column by measuring, and the blood pressure is normal, it is considered that there is high blood volume, circulatory overload, and excessive pressure. If the test blood pressure is also abnormal, the presence of abnormal cardiac function, such as heart failure, is usually considered. If the central venous pressure is detected as abnormal, prompt medical attention is required.