During central venous catheterization, both in-plane and out-of-plane techniques can be used. In the in-plane technique, the entire needle can be visualized with ultrasound. In the in-plane technique with a linear probe, the vessel and needle are visualized longitudinally. In the syringe technique, a guide needle attached to a syringe is first inserted into the vein and blood is aspirated, then the catheter is placed through a wire sent into the vein via the needle. This procedure is performed under ultrasound guidance, visualizing the vessels, guide wire, and needle.

In the syringe-less technique, the guide wire is placed inside the needle and sent directly into the vein. In this technique, there is no need to draw blood into the syringe to confirm that it is in the vein.

The aim of our study is to compare the two ultrasound-guided techniques in terms of procedure time, number of attempts, and complication rates. We expect the syringe-less technique to have a shorter procedure time, fewer attempts, and a lower complication rate.

Today, central venous catheters are frequently placed in operating rooms, intensive care units, and emergency departments for reasons such as intravenous fluid and drug infusion, measurement of cardiac parameters, inability to find a vein, total parenteral nutrition, septic shock, and similar critical illnesses. Performing central venous catheterization under ultrasound guidance has reduced the number of attempts, procedure time, and intra-procedure complications. International guidelines recommend the standard use of ultrasound in central venous catheterization. During ultrasound-guided central venous catheter placement, the vessels and needle can be simultaneously visualized. Both in-plane and out-of-plane techniques can be used during the catheterization procedure. In the in-plane technique, the entire needle is visualized by ultrasound. In the in-plane technique with a linear probe, the vessel and needle are visualized longitudinally. In the syringe technique, a guide needle attached to a syringe is first inserted into the vein to aspirate blood, and then the catheter is placed through a wire sent into the vein via the needle. This procedure is performed under ultrasound guidance, visualizing the vessels, guide wire, and needle.

In the syringe technique, a guide needle attached to a syringe is first inserted into the vein to aspirate blood, and then the catheter is placed through a wire sent into the vein via the needle. In the syringe-free technique, a guide wire is placed inside the needle and directly inserted into the vein. In this technique, there is no need to draw blood into a syringe to confirm that the needle is in the vein.

The aim of our study is to compare two ultrasound-guided techniques in terms of procedure time, number of attempts, and complication rates. We expect the syringe-free technique to have a shorter procedure time, fewer attempts, and a lower complication rate.

Materials and Methods Section:

The study was designed as a prospective, randomized, and single-blind study. Patients aged 18-85 years with an indication for central venous catheterization will be included in the study. Informed consent will be obtained from patients who will undergo surgery under general anesthesia before the anesthesia procedure.

Patients included in the study will be divided into two groups using computer-assisted randomization.

Patients in the first group will undergo central catheterization of the jugular vein using the Seldinger method (first inserting a guide wire and then inserting the catheter) with ultrasound guidance using an out-of-plane technique.

In the second group of patients, central jugular vein catheterization will be performed using the Seldinger method (with a guide wire) with in-plane technique (longitudinal visualization of the entire needle and vessel) under ultrasound guidance. A linear ultrasound probe will be used in both groups of patients during the procedure. The number of needle insertions, needle placements, number of attempts, and procedure time will be recorded and compared for both groups. In addition, rare complications such as bleeding, hemothorax, pneumothorax, hematoma, and carotid artery injury will be recorded. The ease of the procedure will be scored by the practitioner on a scale of 0 to 10 (0: most difficult, 10: easiest). The appearance of the needle, vessels, guide wire, and catheter on ultrasound will also be scored and recorded on a scale of 1 to 5 (very difficult: 1, difficult: 2, moderate: 3, easy appearance: 4, excellent: 5).

The recorded data will be compared between the two groups.

Inclusion Criteria:

Patients aged 18-85 years with indications for central venous catheterization in the operating room.

Exclusion Criteria:

Morbidly obese patients (BMI >40) Patients with severe coagulopathy Patients with severe neck deformity Patients with skin deformity or infection at the catheterization site Patients with congenital anomalies in the central veins

Sample Selection:

Considering previous studies on this subject, a total of 80 patients in both groups are needed to shorten the procedure time by 30%. Considering patients who may be excluded from the study, a total of 90 patients were planned to be included (α: 0.05, power 90%).

Statistical Method to be Used:

Continuous quantitative data will be presented as number, mean ± standard deviation. Qualitative variables will be expressed as median, 25th and 75th percentiles. Continuous variables with independent measurements and a normal distribution will be analyzed using the T-test. For data that do not show a normal distribution, the Mann-Whitney test will be applied. Chi-square tests will be applied to categorical data, and p <0.05 will be considered statistically significant.

Inclusion Criteria:

• Patients aged 18-85 years who have an indication for central venous catheterization in the operating room.

Exclusion Criteria:

• Morbidly obese patients (body mass index >40)
• Those with severe coagulopathy
• Severe neck deformity
• Skin deformity or infection at the catheterization site
• Those with congenital anomalies in the central veins

Patient demographic data Study protocol Statistical analysis data

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