Central venous catheters (CVC) are commonly inserted in surgical or critically ill patients. However, CVC placement can cause severe complications. To reduce the incidence of complications and increase procedural safety and quality, ultrasound (US)-guided CVC insertion is recommended by various scientific societies, including the American Society of Anesthesiologists.

During conventional US-guided CVC placement, the correct position of the needle tip in the venous vessel is confirmed by direct US visualization and aspiration of blood using a syringe connected to the needle. After blood aspiration, the operator must discontinue US-guidance to disconnect the syringe and the needle and to pass the guidewire through the needle (without direct US visualization). This step bears the risks of dislocating the needle tip and puncturing the posterior wall of the target vein or an adjacent artery.

Some authors thus propose an US-guided wire-in-needle technique - in which the guidewire is directly adapted to the needle (without a syringe) from the beginning of the procedure and the guidewire is advanced under direct US visualization. Whether the wire-in-needle technique decreases the procedure time, the number of needle passes, and complications compared to conventional US-guided CVC remains scarcely investigated. We thus propose a randomized controlled trial to investigate whether the US-guided wire-in-needle technique for CVC placement in the internal jugular vein (IJV) is faster and safer than the conventional US-guided technique in patients having cardiac surgery.

Patients scheduled for elective cardiac surgery receive a CVC and sheath introducer central line in the same internal jugular vein. Both catheters require the insertion of a guidewire into the vein to insert the catheter (seldinger technique). The anesthesiologist is going to place both guidewires before advancing the catheters over the guidewires.

The IJV will be examined before catheter placement to confirm that a long-axis view is possible. The right IJV will be chosen for CVC and sheath introducer central line placement. Patients will be then randomized to the US-guided wire-in-needle technique or the conventional US-guided technique just before catheter placement. Randomization will thus be concealed until the last practical moment. The patients will be randomized by a computer algorithm. Patients will be blinded to group allocation.

Anesthesiologists inserting the catheters will have at least 2-month experience in both US-guided wire-in-needle technique or the conventional US-guided technique. Patients will be equipped with basic anesthetic monitoring (electrocardiogram, pulse oximetry, upper-arm cuff oscillometry) and an arterial catheter. All patients will be intubated and mechanically ventilated during the procedure. The patient will be placed in a 15° Trendelenburg position. Catheter placement will be performed under sterile conditions with the US probe covered with a sterile cover.

US-guided wire-in-needle technique The guidewire will be connected to the needle. The IJV will be punctured in a long-axis in-plane approach. When the needle tip enters the IJV, the guidewire will be advanced through the needle into the IJV under continuous ultrasound visualization. The needle will then be removed. The correct guidewire position in the IJV will be confirmed in the long-axis and short-axis view. Afterwards, the second guidewire will be placed in the same IJV approximately 1-2 centimeters distal to the fist guidewire using the same technique. The correct guidewire position in the IJV will be confirmed in the long-axis and short-axis view again.

Traditional technique A syringe will be connected to the needle. The IJV will be punctured in a long-axis in-plane or short-axis out-of-plane approach (as preferred by the anesthesiologist). When the needle tip enters the IJV, blood is aspirated using the syringe. The operator will then discontinue US-guidance, disconnect the syringe and advance the guidewire through the needle into the IJV. The needle will then be removed. The correct guidewire position in the IJV will be confirmed in the long-axis and short-axis view. Afterwards, the second guidewire will be placed in the same IJV approximately 1-2 centimeters distal to the fist guidewire using the same technique. The correct guidewire position in the IJV will be confirmed in the long-axis and short-axis view again.

Inclusion Criteria:

• patients scheduled for elective cardiac surgery at the University Heart Center Hamburg-Eppendorf in whom CVC placement and sheath introducer central line placement in the internal jugular vein is indicated for clinical reasons unrelated to the study
• age > 18 years
• Written informed consent

Exclusion Criteria:

• longitudinal (long axis) view cannot be performed because of anatomical reasons (e.g., short neck).