cvc is a central venous catheter placed in a large vein called a cannula. 1. clinically used to measure central venous pressure to assess circulatory physiological parameters as well as to estimate the amount of rehydration. 2. suitable for large and rapid intravenous infusion, long-term parenteral nutrition, long-term antibiotic injection, long-term painkiller injection. 3. for drugs with strong irritation in the peripheral vasculature, they can be injected from a central venous catheter, such as amiodarone. . 4.It is the pipeline of hemodialysis, such as plasma replacement. 5.Chemotherapy of tumor, prevent the occurrence of chemical phlebitis, prevent drug extravasation. 6.Establish good infusion access for patients with repeated infusion, avoid the pain of repeated puncture, establish infusion access for patients with serious illness.