The kidneys are the body’s natural filtration system. These small organs cleanse the blood of excess fluids and wastes, a function that is vital to health and life. In situations where kidney function has been significantly impaired, dialysis becomes necessary. Dialysis is the treatment modality that maintains the work of the kidneys using machines or a cleansing solution. In order for dialysis to occur, the patient needs an access point of some sort. This is the path through which blood is accessed for filtration. Dialysis may occur in one of two ways. Hemodialysis is the method of removing blood from the body and running it through a dialyzer before it is sent back into the body. Peritoneal dialysis is the method of infusing the abdominal lining with a special solution that picks up wastes and fluid from the blood. Here, we discuss the four types of access that are involved in these two methods of dialysis.
Arteriovenous (AV) Fistula
A preferred method of hemodialysis, the arteriovenous (AV) fistula access is most commonly inserted into the non-dominant arm. The process involves connecting a vein to an artery. When connected, the artery directs more blood through the vein, causing it to increase in size. Blood also flows more quickly through the vein. The enlarged vein is then primed for access via a needle. During dialysis, blood exits the body through one needle, runs through the dialyzer, the machine that filters out wastes and excess fluid, and returns to the body via a second needle. While the AV fistula is efficient and relatively low risk due to the absence of an open access point, this method requires months of healing before dialysis can begin. Therefore, it is important to consider kidney function and the timing of dialysis treatment.
Arteriovenous (AV) Graft
The arteriovenous (AV) graft is a type of access in which an artificial fistula is created. Patients with very small veins, venous scarring, or sclerosis may not be good candidates for an arteriovenous (AV) fistula as it is normally performed. The AV graft involves the use of flexible biocompatible tubing to create the connection between the vein and the artery. Rather than inserting one needle into the vein and another into the artery during hemodialysis, the technician inserts needles into the graft tubing, instead. From that point, dialysis occurs as normal. An AV graft is more readily available after insertion than an AV fistula. However, the presence of the graft increases risks for infection and clotting.
Central Venous Catheter (CVC)
The Central Venous Catheter facilitates hemodialysis via a catheter placed into a large vein. Usually, the vascular specialist uses a vein in the neck or upper chest. After inserting the catheter, the specialist progresses its tip to rest at the upper right chamber of the heart. The other end of the flexible tube is externally situated. It has two “limbs” that connect to the dialysis machine via flexible tubing. During dialysis, blood travels through one limb of the catheter into the dialyzer. It is then returned to the body via the other limb. The CVC is usually used only as a temporary access point because it carries a higher risk of infection and clotting and requires patients to take special care of the catheter’s exit point when bathing.
Peritoneal Dialysis (PD)
Unlike hemodialysis, which filters blood using a machine, peritoneal dialysis does so using a special solution. The peritoneal dialysis access is within the abdominal cavity. To create access, the vascular specialist inserts the small PD catheter through the skin and progresses the tube to the lining of the abdominal cavity. Dialysis treatments then consist of opening the external port of the catheter and connecting to a bag of fluid. The solution flows into the abdominal lining and, when the bag is empty, the catheter is closed. Though the patient may feel bloated due to the infusion of fluid, they may go about their normal activities for a few hours. After some time, they return to the center to have the solution drained. The drained solution carries wastes and excess fluid it has picked up. Patients may feel a greater sense of freedom using peritoneal dialysis but must remember that the exit point of their access must be kept clean to manage the risk of infection.
Choosing dialysis access is one of the first steps a patient must take in managing their treatment program. For more information or to schedule a visit at Vascular Institute of Virginia, contact us at 703-763-5224. We have offices in Fredericksburg, Woodbridge, and Fairfax.