PICC is a method of sending peripheral central venous catheter from cubital fossa vein to superior vena cava, which has developed into a convenient, effective and safe catheterization technique. The infection rate of central venous catheterization was 0. 18% in the United States and 1. 1% in Taiwan Province province. However, 90 cases were punctured with PICC90, and none of the 10 cases in our department was infected [2]. Due to lack of experience, some complications have occurred. The catheter was placed for 7 days. 1 patient, considering that the catheter was inserted too quickly, the catheter was sent to the vascular branch and entered the axillary vein. The effect of raising the affected limb after hot compress is not good, and the effect is satisfactory after extubation. Two days after catheterization, 1 the patient found that the fingers and the back of the hand were obviously swollen, and the symptoms disappeared after two days by hot compress, raising the affected limb and heparin saline twice a day. 1 patient intubated. Symptoms disappeared after 2 days, which may be related to catheter placement in jugular vein. Although the infection rate of PICC is low, there is still the risk of iatrogenic infection as a central venous catheter. Therefore, strict aseptic operation should be carried out in the process of tube placement and film replacement to avoid infection. Although blood pressure, heart rate, urine volume and PTCO _ 2 can reflect the circulatory changes, they lack specificity and cannot identify the complex causes of circulatory changes. CVP can provide more information at this time. Blood volume is an important factor that constitutes CVP, but it is not the only factor. Besides volume, cardiovascular compliance, chest pressure and myocardial contractility all affect CVP. These factors may not be important under normal circumstances, but they may become very prominent under pathological conditions, thus affecting the judgment of ability. In this case, it is not reliable to judge the capacity by CVP, and its function is mainly to evaluate the potential of the right heart to accept the capacity load. Therefore, the capacity load test based on the characteristics of capacity-pressure relationship is adopted. It can be used as a treatment reference for patients with high CVP but still with clinical manifestations of insufficient cardiac output. If 500ml liquid is injected quickly within 20min minutes, CVP will not increase significantly, or even decrease; At the same time, the blood pressure increases and the heart rate decreases, indicating that the patient has absolute or relative capacity deficiency, and the heart may continue to receive a lot of infusion; On the contrary, infusion must be careful. So the value of CVP is reflected in its dynamic changes and observations, not just an isolated value. When the left and right hearts are coordinated and the pulmonary vascular resistance is normal, CVP can reflect both left and right heart functions. But in critically ill patients, many pathological factors can change the above relationship. Therefore, when the increase of CVP is large, even if it is confirmed that right ventricular dysfunction has occurred, it is not appropriate to restrict infusion immediately, but to monitor pulmonary wedge pressure (PAWP) at the same time. A new view is that if right heart failure is accompanied by low PAWP and low cardiac output, positive inotropic drugs can be given while maintaining infusion to maintain adequate cardiac output. In principle, when dealing with the problem of right heart, we should also consider the influence on left heart and put it in a more important position. Based on this, right heart failure caused by pulmonary embolism and pulmonary hypertension needs careful treatment. In this kind of right heart failure, increasing infusion and using positive inotropic drugs can not increase left heart filling as expected, on the contrary, it often leads to a further sharp increase in right heart pressure, which severely compresses the interventricular septum to the left, or reduces the left ventricular volume due to pericardial restriction, which further reduces the left cardiac output. Therefore, infusion should be limited for this kind of right heart failure, and the right atrial pressure (RAP) should be controlled within 2. 67 kPa.