What is an arteriovenous fistula?
An arteriovenous fistula is a surgically crafted connection between a vein and an artery (usually in the arm). Sometimes an artificial graft is used for the same purpose. 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.
During dialysis (hemodialysis) a needle is placed in the fistula 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 fistula.
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. 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.
Typically the procedure is performed on a day case basis unless you are already in hospital. Usually, it is performed under local anaesthesia (perhaps with some sedation). Sometimes, the procedure is done under General Anaesthesia.
Depending upon the quality of your artery and vein, your surgeon will try to construct the fistula with one incision in 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.
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 38 degrees
- 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 dialysis access nurse will advise you on these exercises.
Are there any complications?
Complications with dialysis access include:
- “steal” where the blood flow through the fistula is too great and there is insufficient blood going to the hand. This may require modification or even ligation of the fistula
- narrowing or stenosis in the fistula which reduces the flow
- aneurysm formation in the access itself
- nerve injury causing pain, altered sensation or weakness.
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 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 apply direct pressure to the bleeding site & 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
For further information, you should ask your dialysis access nurse, your vascular surgeon or nephrologist one of the nurses in the dialysis unit.