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PATIENT INFO - DIALYSIS AV FISTULA
Dialysis
Once kidney function goes below 10 to 15 percent of normal, dialysis treatments or a kidney transplant are necessary to sustain life. There are two types of dialysis: hemodialysis and peritoneal dialysis. Both dialysis treatments are able to replace the kidneys’ function of cleaning the blood of toxins and removing extra fluids for people with kidney failure.The type of access a person has is important for getting the best dialysis possible. There are three types of access: catheter, arteriovenous (AV) graft and arteriovenous (AV) fistula.
Catheters
A catheter is a flexible, hollow tube inserted into a large vein in your neck, chest, or leg near the groin which allows the blood to flow into and out of your body. A catheter is most commonly used as a temporary dialysis access. There are several places on your body where a catheter can be placed.
The most common are:
- Internal jugular catheter - inserted into the jugular vein on the side of the neck.
- Subclavian catheter - placed into the subclavian vein under the collar bone on the chest.
- Femoral catheter - placed in the large vein in the leg near the groin
Arteriovenous Graft
If a patient is not a good candidate for an arteriovenous fistula, an arteriovenous graft is considered. An arteriovenous graft is a piece of artificial tubing, generally made out of teflon or fabric, that is attached on one end to an artery, and on the other end to a vein. The tube is placed entirely under the skin and the tube itself is punctured during dialysis. An arteriovenous graft can in general be used two to three weeks after the operation. However, arteriovenous grafts are more prone to infection and clotting than fistulas. The lifespan of an arteriovenous graft is approximately two to three years.
Arteriovenous (AV) fistula
A fistula used for hemodialysis is a direct connection of an artery to a vein. Once the fistula is created it is a natural part of the body. This is the preferred type of access because once the fistula properly matures and gets bigger and stronger; it provides an access with good blood flow that can last for decades. After the fistula is surgically created, it can take weeks to months before the fistula matures and is ready to be used for hemodialysis. People with kidney disease can do exercises including squeezing a rubber ball to strengthen the fistula before use.
Here are some key points to consider before fistula placement:
- The arm that will have the fistula placed needs special care to preserve the veins and improve the chance to obtain a well functioning fistula. Therefore, it is a good idea to limit the drawing of blood to the arm that will not be receiving the fistula.
- Some patients can improve the veins in the arm to be used for their fistula by exercising that arm (squeezing a soft foam ball with a tourniquet placed around the upper part of that arm). Although this approach does not work for all patients, it still may be worth a try.
Buttonhole Technique
In order to preserve your AV fistula, your healthcare team may introduce a special technique for needle insertion called the Buttonhole Technique. This technique can only be used with an AV fistula. Inserting needles into the access is called cannulation. Buttonhole is a special cannulation method where an individual cannulates the AV fistula in the exact same spot, at the same angle and depth every treatment. The track is a tunnel that is created by the formation of scar tissue similar to the hole created in an earlobe for a pierced earring. This track goes from the surface of your skin to the outside wall of your fistula. Special needles are required for the buttonhole technique. Once the track is well healed, there are no nerves or tissue in the path of the needle to cause you pain. This method is best suited for the person who chooses to self-cannulate (inserting your own needles) or may be used by the dialysis clinic staff. Several other methods of cannulation can also be used, and can be discussed with your healthcare team.
Benifits of AV Fistula
The benefits of AVFs over other forms of chronic access are summarized below and discussed in detail elsewhere.
- AVFs are associated with decreased morbidity and mortality among hemodialysis patients compared with AV grafts and central venous catheters .
- AVFs have the superior primary patency rates, the lowest rates of thrombosis, and require the fewest secondary interventions .
- AVFs generally provide longer hemodialysis access survival rates .
- The total number of interventions during the life of the access is considerably lower for AVFs compared with AV grafts .
- AVFs have lower rates of infection than AV grafts and significantly lower infection rates compared with percutaneous catheters .
- Patients with AVFs have lower hospitalization rates than patients with AV grafts or catheters .
- The cost of implantation and maintenance of AVFs is the lowest of the three types of access .
Effects of AV Fistula
There are several cardiovascular effects of AVF creation. These include:
- Increased cardiac output.
- Decreased systemic peripheral resistance.
- Increased sympathetic activity with increased contractility, heart rate and stroke volume.
- Increased blood volume with increased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and left ventricular end-diastolic volume.
- Increased pulmonary flow and pressure.