2.3. Randomization
The experimental group and the control group are randomly divided into 1:1. Random method: Random numbers are generated using SPSS 25.0 statistical software by the center’s personnel in charge of randomization, and group by the rank of the random number and group principle. Opaque envelopes are used to lock the results, and the envelopes are numbered. When a patient needs CVCs, the envelope is opened in numerical order to determine whether the patient is admitted to the experimental or control group. The allocation order is hidden until the end of the trial.