I. What is PICC central venous catheter via peripheral cannulation, used to provide medium to long-term intravenous therapy for patients (5 days-1 year). The advantages of PICC: 1.reduce the pain of frequent venipuncture and protect the peripheral veins of patients; 2.high success rate and few complications; 3.not easy to dislodge and the fluid flow rate is not affected by the patient’s body position; 4.chemotherapy patients avoid the extravasation of chemotherapy drugs; 5.long retention time, the catheter can be left for up to 1 year; 6.can be inserted by the nurse at the patient’s bedside without local anesthesia and suture fixation. Indications for PICC: 1.Tendency of lack of peripheral venous access; 2.Need to infuse irritating drugs, such as chemotherapy drugs; 3.Need to infuse hypertonic or viscous fluids, such as intravenous hypernutrition; 4.Need for long-term intravenous treatment, such as rehydration or pain treatment; 5.Also applicable to children (4 years old and above, children who can cooperate). IV. Contraindications to PICC: 1. peripheral veins cannot be identified; 2. poor patient compliance; 3. pre-insertion route with history of venous thrombosis, source of infection, history of trauma, history of vascular surgery, history of radiation therapy; 4. severe bleeding disorders; 5. superior vena cava compression syndrome; 6. vascular malformation. V. Choice of catheter – catheter with three valves: 1. reduce the risk of blood return and air embolism; 2. no need to use catheter clamps, reducing the chance of catheter damage; 3. only need to flush once every 7 days between treatments, greatly reducing the risk of infection. Precautions: 1.Handling of bleeding; 2.Handling of hand swelling; 3.Time for changing film, flushing and needleless connector; 4.Prevention and treatment of phlebitis; 6.Suspected contamination, sweating, film rolled edge and other special circumstances, should be replaced at any time; 7.Do not lift heavy objects in the placement arm, do not do vigorous exercise, can move freely; 8.Patients carry the PICC placement maintenance register every time when changing film.