Central Venous Access Devices (CVADS)
Central venous access device, or CVAD, is a broad term that includes many types of catheters (thin, flexible hollow tubes) that are inserted into and positioned within a vein in the body to deliver therapies to the bloodstream or withdraw blood for testing. CVADs are used to provide life-saving medications and critical treatment, such as chemotherapy for cancer patients, supplements for patients at risk for malnutrition who cannot receive nutrients via the digestive tract, and antibiotics for patients with severe infections.
An estimated 5 million CVADs are placed each year in the U.S., and this number is increasing as the population ages.
Varying types of CVAD are used for different conditions and therapies. There are two general types of CVADs: catheters and ports. Catheters have one end positioned outside the body, while ports are surgically placed under the skin and require a special needle for access. With both catheters and ports, the opposite end of the tubing is positioned within the large vein near the heart. The most common CVADs include:
- Peripherally inserted central catheters (PICCs)--inserted into one of the peripheral veins in the upper arm
- Nontunneled percutaneous central venous catheters--inserted into the subclavian vein (in the chest) or jugular vein (in the neck)
- Tunneled central venous catheters--inserted into the subclavian vein or jugular vein; subcutaneous tissue grows into the polyester fiber cuff surrounding and therefore stabilizing the catheter
- Implanted ports--inserted into the subclavian vein or jugular vein and attached to a fluid reservoir placed in a surgically created subcutaneous pocket on the upper chest, or into an arm vein with a peripheral port pocket
Occlusions are a common complication associated with CVADs. It is estimated that 25 percent of all CVADs become occluded and that 60 percent of these occlusions are caused by thrombosis, the formation of a blood clot.
When CVADs become occluded, many complications can occur, including the inability to inject or infuse solutions and/or the inability to withdraw blood.
Occlusions are generally classified as:
- Thrombotic: A blood clot, or thrombus, typically develops over time when fibrin, a naturally-occurring substance that promotes blood coagulation, builds up near or around the tip of the CVAD.
- Mechanical: These occlusions occur when the tube is pinched (which is often observed when a CVAD catheter is placed between the rib and the collarbone), when the catheter tip moves into a smaller vein or when the tube becomes blocked against the vessel wall.
- Precipitate: Precipitate occlusions may occur when two or more incompatible drugs or nutritionals interact and the resulting sediment remains in the CVAD, often causing disruption of fluid transmission. Nutritionals may also leave a waxy buildup of lipids on the CVAD catheter wall.
While thrombotic occlusions develop over time, mechanical and precipitate occlusions typically form spontaneously.