Choice of catheter

It is important that the catheter selected should be applicable to the anatomical route of insertion and due regard should be given to the length of time for which the device will be in place. The selection of the central venous catheter should also take into account the known complications that have been documented.

Central venous catheters introduced using a through-needle technique are obsolete and should not be used since there is a serious risk of catheter embolization occurring during insertion. The safest techniques involve either a Seldinger wire technique or a through-cannula introducer. Over-needle single lumen devices are a satisfactory alternative, particularly for the internal jugular route.

It is wise to avoid catheter types which have 'disconnecting hubs'. Fixed-hub devices provide extra security against the catheter inadvertently snaking into the circulation and disconnection leading to air embolism. The union between catheter and shaft is a potential source of bacterial contamination from the body's surface and can be eliminated by a suitable chemical and mechanical bonding process.

A great deal of research has been performed in respect of the most suitable and least thrombogenic material for use in central venous catheterization. It is likely that there will always be a risk of thrombosis in association with these devices. The advent of silicone rubber and polyurethane polymers has been of great benefit to patients.

In adults, for the approaches using the arm, a 60- to 70-cm catheter is necessary in order to reach the superior vena cava. However, shorter catheters are now being used where the tip rests in the more proximal reaches of the subclavian or innominate veins. For the subclavian route, a 30- to 35-cm catheter is necessary, and for the internal jugular route a 12- to 15-cm length of catheter is required. The correct choice of length is important to avoid malposition. The majority of short Teflon over-needle jugular catheters are inappropriately 'stiff' when introduced into the subclavian vein with the risk of perforation of the superior vena cava or innominate vein. Movement of the patient's shoulder or infusion line will cause a to-and-fro movement of the relatively rigid catheter tip against the endothelium of the vein.

The various tunneling techniques naturally require catheters with different specifications and at the present time these are usually 90 to 110 cm in length. It is vital that the hubs of these devices are more resilient for their intended long-term placement.

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