**3. Percutaneous insertion of central venous catheter**

As mentioned, the right internal jugular vein is the preferred site as the curve of the catheter is straight thus achieving the best result. If the left internal jugular vein is used, negotiation of the curve at the venous entry to the superior vena cava may require experience and care. Moreover, one must choose a longer catheter as compared with right jugular vein puncture. The length of catheter introduced from neck or thoracic access should enable its distal end to reach the right atrium when a soft catheter is used or be placed in the superior or inferior vena cava when the catheter is stiff. It is recommended to place hemodialysis CVCs under fluoroscopic screening to avoid trauma with the guidewire in the inferior vena cava during insertion and the distal part of catheter in the upper right atrium upon completion of placement (Lin et al 1998, Keenan 2002).

The first choice for catheterization is the right internal jugular vein, followed by the right external jugular vein, left internal jugular vein, left external jugular vein, and finally femoral

Tunneled CVCs with cuffs are made of silicone, silastic or carbothane elastomer, polyurethane co-polymer and polycarbonate − these materials are softer and more plastic than those used in temporary catheters. Therefore, they are usually inserted using the Seldinger technique via peel-away sheath. Subcutaneous tunnelization and a cuff are to stabilize the catheter and prevent the spread of infections. The soft silastic elastomer enables the placement of the distal catheter tip in the right atrium, which should be confirmed by fluoroscopy. Bigger internal diameters (thicker catheters) provide better blood flows and a

The first model of a tunneled catheter was PermCath, an oval catheter with two circular canals. Subsequent models (e.g. Vas Cath) were designed with an internal septum dividing the internal lumen into two parts. The oval transverse section of the catheter facilitated its insertion through the peel-away sheath. The third popular option was the introduction of two catheters with a single lumen – Tesio or its modification. One collected the blood through the opening in the superior vena cava and the other one supplied blood through the opening in the right atrium. Other than the catheter body and lumen, the design of the shape of catheter tips is also emphasized for better blood flow, improved reliability and

The newest catheters implanted surgically are equipped with a subcutaneous port (Morgan 2001, Ross 2001), which reduces percutaneous device-related complications. In most cases, the port consists of a chamber made of a titanium, ceramics or other neutral plastic materials with silicone membrane and an attachable catheter. The silicone membrane enables repeated penetrations (about 1000-2000), depending on the product and size of the puncture needle. The entire system is placed under the skin, which prevents infections or accidental opening. There are different configurations of the catheter and port chamber from using two single catheters each attached to a single chamber port to a double-lumen catheter connected to a two-chamber port. The vascular port implantation is based on the same principles as those for central venous access except the ports are placed in a subcutaneous pocket. The port can be punctured with normal hemodialysis needles or needles with special make that does not cut an opening in the membrane. The main reason of low popularity of hemodialysis ports

As mentioned, the right internal jugular vein is the preferred site as the curve of the catheter is straight thus achieving the best result. If the left internal jugular vein is used, negotiation of the curve at the venous entry to the superior vena cava may require experience and care. Moreover, one must choose a longer catheter as compared with right jugular vein puncture. The length of catheter introduced from neck or thoracic access should enable its distal end to reach the right atrium when a soft catheter is used or be placed in the superior or inferior vena cava when the catheter is stiff. It is recommended to place hemodialysis CVCs under fluoroscopic screening to avoid trauma with the guidewire in the inferior vena cava during insertion and the distal part of catheter in the upper right atrium upon completion of

The first choice for catheterization is the right internal jugular vein, followed by the right external jugular vein, left internal jugular vein, left external jugular vein, and finally femoral

*ii. Long-term tunneled catheters* 

minimizing recirculation (Ash 2008).

is their relatively high cost.

placement (Lin et al 1998, Keenan 2002).

wider dilator or sequential dilator is frequently used.

**3. Percutaneous insertion of central venous catheter** 

veins or external iliac veins (Maya et al 2005). The vein should be localized by ultrasound and can be differentiated from the artery by Doppler. The probe should first be placed on the head of the sternomastoid muscle and then moves down towards the clavicle. The puncture site should be as low as possible but above the clavicle whereas the exit of the subcutaneous tunnel should preferably be below the clavicle.

Femoral and external iliac veins may be used for CVC insertion in bed-ridden patients or in the intensive care setting, particularly in patients requiring artificial lung ventilation, after head and neck trauma with numerous catheters and drains of the neck and thorax as well as those with tracheostomy (Zaleski et al 1999, Mathur et al 1993). Patients with kidney transplant potential should avoid femoral vein catheterization. With catheter insertion in the groin, meticulous hygiene of the puncture site is required. The patency period from the insertion to removal is markedly shorter in femoral vein access compared to catheters inserted through the internal jugular vein.
