What is dialysis access?
In the context of this article, dialysis access is an entranceway into your bloodstream that lies completely beneath your skin and is easy to use. The access is usually in your arm, but sometimes in the leg, and allows blood to be removed and returned quickly, efficiently, and safely during dialysis or, less commonly, for other procedures requiring frequent access to your circulation.
Dialysis, also called hemodialysis, is the most common treatment for kidney failure. A dialysis machine is an artificial kidney designed to remove impurities from your blood. During dialysis, physicians use the dialysis access to remove a portion of your blood to circulate it through the dialysis machine so it can remove impurities and regulate fluid and chemical balances. The purified blood is then returned to you, again through the dialysis access.
Creating the access portal is a minor surgical procedure. There are two types of portals placed completely under the skin:
- Fistula, which your vascular surgeon constructs by joining an artery to a vein
- Graft, which is a man-made tube, consisting of a plastic or other material, that your vascular surgeon inserts under the skin to connect an artery to a vein
For both fistulas and grafts, the connection between your artery and vein increases blood flow through the vein. In response, your vein stretches and becomes strengthened. This allows an even greater amount of blood to pass through the vein and allows your dialysis to proceed efficiently. In the weeks after surgery, the fistula begins to mature. The vein increases in size and may look like a cord under your skin. The whole process of maturation, which is a beneficial feature that permits the blood flow to increase in the fistula, typically takes 3 to 6 months. Some fistulas may take as long as a year or more to develop fully, but this is unusual. Once matured, a fistula should be large and strong enough for dialysis technicians and nurses to insert the large dialysis needles easily. If it fails to mature in a reasonable period of time, however, you may need another fistula.
A graft placed between an artery and vein can usually be used for dialysis within 2-6 weeks, when it is healed sufficiently. Usually fistulas are preferred to grafts, however, because fistulas are constructed using your own tissue, which is more durable and resistant to infection than are grafts. However, if your vein is blocked or too small to use, the graft provides a good alternative.
How do I prepare?
Before choosing the access site, your surgeon may ask you if you have a history or symptoms of arm or leg artery disease. Hardening of the arteries, which reduces blood flow to your arms or legs, often can cause these conditions. Your vascular surgeon will not place a dialysis access site in an area of the body with reduced circulation because the blood flow will be insufficient. For this reason, your surgeon usually places dialysis access sites in the arms rather than in the legs because atherosclerosis is more common in the legs.
Your vascular surgeon may order a blood flow test in your arms and legs, such as an ultrasound exam, or an x ray, such as a venogram, to determine whether your veins are large enough to use for a fistula. Sometimes a non-invasive pulse volume recording test is used to evaluate the flow in your arteries if this issue is a concern to your surgeon.
Your vascular surgeon will give you the necessary instructions you need to follow before the surgery, such as fasting. Usually, your physician will ask you not to eat or drink anything 8 hours before your procedure. Your physician will discuss with you whether to reduce or stop any medications that might increase your risk of bleeding or other complications.
Am I eligible for dialysis access?
If you have chronic kidney failure and need long-term hemodialysis, you may require dialysis access. You may not be a good candidate for a fistula if your veins are too small or are scarred from frequent placement of intravenous catheters (thin, flexible tubes inserted into veins to deliver medicine) or needles to draw blood. In that event, you may be eligible for a graft access procedure. You also may not be a good candidate for a fistula if your arteries are severely blocked, although they might be repairable if necessary. Your vascular surgeon will probably be reluctant to use a graft if you have an ongoing infection since the graft itself might become infected. If this happens, the infected graft might need to be removed in order to clear up the infection.
What happens during dialysis access?
Typically you will have the procedure on an outpatient basis. Most often, you will first be sedated and then your surgeon will numb the area where the fistula or graft will go. In some cases, your anesthesiologist may give you supplemental sedation or put you to sleep.
Depending upon the quality of your artery and vein, your surgeon will try to construct the fistula with one incision using the forearm of the arm that you do not use as frequently. For example, if you're left handed, your physician will place the fistula in your right arm, if possible. To perform the surgery, your physician joins a large vein under the skin to an artery nearby. The physician divides your vein and sews it to an opening made in the side of the artery. As a result, the blood flows down the arteries into the hand, as usual, and also some of this faster moving blood flows into the veins that lead back to your heart. The blood that normally traveled in your divided vein goes back to the heart through other veins, and there is usually plenty of blood remaining in your artery to supply your hand.
If you cannot receive a fistula because the vein is too small or blocked, your physician may construct a graft using a tube of man-made, plastic material. Less commonly, your physician may also choose to use a piece of a vein from your leg or a section of artery from a cow as alternative graft materials. Your physician sews the graft to one of your veins and connects the other end to an artery. Your physician may place the graft material straight or form a loop under the skin either in your lower arm, upper arm, or less commonly in your leg.
What can I expect after dialysis access?
After the operation, you should initially keep the access area raised above your heart to reduce swelling and pain. Your surgeon may recommend an over-the-counter painkiller to relieve pain, if necessary.
Following the suggestions below will help you keep your new access site working properly in the weeks after the surgery:
- Keep the incision dry for at least 2 days after the procedure and do not soak or scrub the incision until it has healed
- Avoid lifting more than about 15 pounds or other activities that stress or compress the access area, such as digging
- Report pain, swelling, or bleeding immediately to your physician, especially if these symptoms are becoming worse. Some pain or swelling is common and not worrisome if decreasing, but you should tell your physician if you have bleeding, drainage or a fever higher than 101 degrees Fahrenheit
You may initially feel some coolness or numbness in the hand with the fistula. These sensations usually go away in a few weeks as your circulation compensates for the fistula. However, if these sensations are severe or don’t disappear, tell your physician as soon as possible, because the fistula may be causing too much blood to flow away from your hand, a condition physicians call a “steal.”
You should perform exercises to grow and strengthen your fistula, after the pain from the surgery decreases, to make dialysis faster and easier. Your physician may recommend squeezing a soft object using the hand on the arm in which the fistula was placed.
Grafts may mature more quickly than fistulas depending upon the size of the vein to which the graft is initially attached. They sometimes can be ready in 2 to 3 weeks, but many physicians recommend waiting about 4 to 6 weeks before using a graft. Grafts have disadvantages over fistulas. Grafts are more likely than fistulas to become infected. Also, grafts usually last about 1 to 2 years, which is less than fistulas, which can often last up to 3 to 7 years. If you care properly for your graft, however, you can help it last for many years.
Sometimes access portals can take weeks or even months until they are ready for dialysis use. Until the portal is ready, you may have to use a catheter for dialysis.
Are there any complications?
Complications with dialysis access include, in addition to “steal” discussed above, clotting, narrowing, aneurysm formation in the access itself, infection, and bleeding.
What can I do to stay healthy?
Protecting the dialysis access is crucial for you. The following tips will help you care for a fistula or a graft:
- Check several times each day to make sure the access is functioning. You should be able to feel a vibration in the fistula called a “thrill.” Your physician or dialysis center staff will show you how to do this
- Monitor any bleeding after dialysis. If the graft seems to bleed longer than usual from the needle sites, you should notify your dialysis center staff
- Do not carry heavy items with the arm that has the access
- Do not sleep on that arm
- Do not wear any clothing or jewelry that binds that arm
- Do not let anyone draw blood or measure blood pressure from that arm
- Do not allow injections to be given into the fistula or graft
- Keep the site of the fistula or graft clean
- After dialysis, monitor the access for signs of infection, such as swelling or redness
- Do not use any creams and lotions over the site of the fistula or graft
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Reviewed February 2011