CVC is an acronym that stands for Central Venous Catheter. The CVC is a plastic cannula inserted directly into a large caliber vein (internal jugular, subclavian, femoral) and which arrives in the superior or inferior vena cava, based on the positioning site.
CVCs have multiple uses, such as drug administration and parenteral nutrition, central venous pressure monitoring, hemodialysis, etc. The central veins, in fact, compared to the peripheral veins, can be approached with catheters of greater diameter, and therefore allow higher flows, and are more resistant to any toxic insults of the substances that are introduced.
There are CVCs of various types and sizes, according to the use they are intended for. For example, in emergency conditions, when it is not possible to find other venous accesses, a CVC of generally small dimensions is positioned, to allow blood sampling and the infusion of drugs, liquids and so on. In patients who must undergo dialysis, on the other hand, the CVCs are larger because work on higher flows; in these cases, three-way catheters are used: one way for aspiration; one way for injection; the smaller way, accessory, for other uses.
Furthermore, CVCs can be differentiated into tunneled or non-tunneled. Non-tunneled CVCs are inserted directly into the vein.
Tunneled CVCs run for a few cm inside a subcutaneous tunnel before entering the vein. This precaution reduces the risk of infection and also the risk of accidental removal. For these reasons, tunneled CVCs are preferred when prolonged central catheterization is required (such as for prolonged hemodialysis, for example).
CVC PLACEMENT
CVC placement is a sterile procedure that does not require an operating room. After preparation of the operating field, local anesthesia and ultrasound-guided puncture of the chosen vein are performed. The puncture can also be performed using anatomical landmarks, without ultrasound guidance, but this approach, the old one, is burdened by greater risks of complications and fewer chances of success. It is therefore always preferable and advisable to use ultrasound guidance, except in situations in which the ultrasound is not immediately available.
After vein access, the catheter is advanced along the venous bed to the superior or inferior vena cava, depending on the access site.
If the procedure is performed in the angiography suite, the correct catheter position can be verified by fluoroscopy (x-rays), otherwise, the x-rays control will be carried out at the end of the procedure.
Post-procedure chest X-rays are mandatory to assess the catheter position but also to evaluate any pulmonary complication. If the CVC is placed in the subclavian vein or in the internal jugular vein, the pleura could be inadvertently punctured. The air could then collects between the lung and the internal part of the rib cage, a condition called "pneumothorax". If small, pneumothorax is often not symptomatic and resolves spontaneously within a few days. The larger ones could lead to a collapse (atelectasis) of the lung with subsequent breathing difficulties. In these cases, a chest drainage tube must be positioned.
Serious complications, then, although rare, can occur. Therefore, CVCs should always be positioned by well-trained personnel, who also know how to deal with any type of complication, from massive pneumothorax to hemorrhage.
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