Non Dilation on the Central Venous Catheterization（NDCVC-01）

The central venous catheter is widely used and used in high dosage, and various complications such as hematoma, hemopneumothorax and arterial puncture may occur during puncture and use. In addition to conventional techniques, studies have been done to improve the success rate of puncture and reduce the incidence of complications by modifying different procedures. However, among the complications caused by the procedure of percutaneous catheter placement, the fatal bleeding caused by skin dilation may threaten the patient' s life. There are few studies on dilators and skin dilation steps at home and abroad. In this study, the conventional puncture technique was improved and the skin dilation step was omitted, hoping to reduce complications, reduce puncture time, improve efficiency and improve patient comfort on the premise of ensuring the success rate of catheterization.

The Central venous catheter is widely used, but there are various complications. During the procedure of skin expansion with central venous catheterization, the use of a dilator can lead to complications such as hematoma, fatal bleeding, discomfort or serious threat to the patient's life. The aim of this study was to eliminate the procedure of skin expansion, to ensure the success rate of catheterization, to reduce complications, to reduce operation time, to improve efficiency, and to improve patients' comfort.

This study is a single-center, prospective, randomized controlled trial.The sample size was calculated by non-inferiority test:(1)the success rate of central venous catheterization was 97.98% according to Meta-analysis references;(2)α =0.025;(3)power 90%;(4)missed follow-up rate 20%, and ultimately 336 samples were included in the study,168 patients in each group.

Patients will receive written and verbal information about the trial before written consent is obtained. Randomization will take place on the day of surgery, and patients will be assigned to the intervention group (direct catheterization with non-dilation) or the control group (catheterization after expanding the skin with a dilator) . The randomization is performed using concealed allocation where envelopes are prepared externally using a randomization list prepared by a research assistant.

Under ultrasound guidance, The patient will undergo central venous catheterization by an experienced anesthesiologist based on grouping information.In the control group, catheter was inserted after skin expansion with dilator, while in the test group, catheter was inserted directly with non-dilator.The success rate of catheterization, the total time of catheterization, and complications were recorded.The patients were followed up for 24 hours after surgery and asked about their comfort level.

Shapiro-Wilk test is used to test normality for continuous variables, with data expressed as mean ± standard deviation, and independent t-test is used for statistical analysis.For categorical data, the incidence of immediate complications is expressed as a percentage (%), and chi square test is used to statistically analyze the incidence of various complications.For the Primary outcome ,success rate of catheterization, the method of confidence interval is used. If the lower limit of confidence interval \> negative non-inferiority threshold, the non-inferiority is considered. P \< 0.05 was considered statistically significant.

Eligibility Criteria:
Inclusion Criteria:

* (1) patients aged 18 years or older
* (2) patients with internal jugular vein catheterization

Exclusion Criteria:

* （1）Patients with infection at the puncture site
* （2）Patients with contraindications to central venous catheterization
* （3）Patients with imaging examination suggesting thrombosis in the internal jugular vein before puncture
* （4）Patients who refused to participate, did not sign or refused to sign the informed consent form