In this prospective, randomized, open-labeled study, the intensive care patients will be selected for ultrasound-guided cannulation of the radial artery in three different regions. Patients will be divided into three groups with simple randomization. The first group will be determined as 'G1' and the radial artery catheterization with ultrasound-guided short axis out of plane intervention will be performed over 2 cm of the wrist for this group. On the second group (G2), radial artery catheterization will be performed in the distal 3/4 area of the forearm with ultrasound-guided short axis out of plane intervention. On the third group (G3), radial arterial catheterization will be performed in the distal 1/2 area of the forearm with ultrasound-guided short axis out of plane interference. Whether there is a difference in the duration of use of arterial cannula, first entry success rates, duration of intervention, number of procedures, the number of cannulas used and the effects on early and late complications and advantages between the groups will be investigated.

In patients requiring frequent arterial blood gas sampling in the intensive care unit and in cases requiring continuous blood pressure monitoring, arterial cannulation is preferred. The use of USG has also become widespread in anesthesia practice. It is supported by studies that USG-guided interventions cause fewer complications compared to classical methods and reduce intervention time. USG-guided arterial catheterization method is based on the principle of direct visualization of the artery and catheter via USG. In this technique, the catheter and the needle tip are displayed simultaneously with the USG guided to the artery lumen. Imaging of anatomical structures with USG has resulted in a reduction of complications and shortening of the processing time. In the USG screen, adjacent anatomical formations such as veins and nerve structures are simultaneously displayed. This reduces the risk of complications.

Two different techniques are used for USG mediated radial artery cannulation. The first one is the in-plane technique, which forms the long axis image of the arteries by positioning the USG probe to parallel to the vein, and the second is the out-of-plane technique, which forms a short axis image with the probe positioned perpendicular to the arteries.

The ideal location of radial artery catheterization with USG or the advantages/disadvantages of the catheterization zone are not available.

In this randomized prospective and open-label study, patients will be divided into three groups. The first group will be determined as 'G1' and the radial artery catheterization with ultrasound-guided short axis out of plane intervention will be performed over 2 cm of the wrist for this group. On the second group (G2), radial artery catheterization will be performed in the distal 3/4 area of the forearm with ultrasound-guided short axis out of plane intervention. On the third group (G3), radial arterial catheterization will be performed in the distal 1/2 area of the forearm with ultrasound-guided short axis out of plane interference. Comparison of these three groups, in terms of duration of use of arterial cannula, initial entry success rates, duration of intervention, number of procedures used, number of cannulas used and effects on early and late complications, and advantages if any is intended.

Patients will be randomly distributed to three groups. Diagnosis, age, sex, height, weight, and body mass index of the patients will be recorded. The random distribution of obese patients to groups will be ensured. Allen test will be done to the patients before the intervention. Radial artery catheterization will be applied only to patients with the collateral flow. Each group will be measured and recorded before, during and after the intervention. Before the intervention, local anesthetic infiltration will be applied and asepsis will be provided. Early complications (such as hematoma, hemorrhage) and late complications (such as circulatory disorders) will be observed and recorded.

Inclusion Criteria:

• Admission of the first degree relatives of the patients and if the patient can give consent
• Patients over 18
• Non-pregnant patients
• Patients without inotropic/vasopressor support
• Patients who do not have contraindications for radial artery cannulation (thrombosis in the distal region, a focus of infection at the site of entry, lack of adequate collateral flow in the Allen test, peripheral vascular diseases [eg, Raynaud's disease)]

Exclusion Criteria:

• Patient/Patient's first degree relatives refuse to work
• Patients under 18
• Pregnant patients
• Patients with contraindications for radial artery cannulation (thrombosis in the distal region, a focus of infection at the site of entry, lack of adequate collateral flow in the Allen test, peripheral vascular diseases [eg, Raynaud's disease)]
• Patient's inotropic/vasopressor support