Kidney Failure and the Arteriovenous Fistula Connection

The Need for AVF
The kidneys are an important part of the body; their main job is to cleanse the blood. When the kidneys fail, an alternative means of regulating and cleansing the blood becomes necessary. The average person has two kidneys located toward the back and just above the waist. When working properly, the kidneys extract waste products from the blood and excess fluid from thousands of pints of blood each day. The kidneys also balance chemicals such as phosphorous and calcium in the blood so that our bodies remain healthy. The blood waste products made up of excess fluid and chemicals are then filtered out by the kidneys to become urine eventually. In addition to those functions, the kidneys help regulate blood pressure and signal the body when to make red blood cells.

If one kidney fails, the other kidney can continue to work and do the job of both. If both kidneys fail, the blood can no longer be filtered, and waste, fluid, and chemicals then build up, and become out of balance within the body. The work of filtering the blood then must be done by a treatment called hemodialysis, which serves to remove the blood from the body in order to clean it.

During hemodialysis treatments, blood is removed from the patient's body through a needle and is run through a tube into a filter that is attached to a dialysis machine, which balances wastes, fluids, and chemicals. After the blood is cleansed by dialysis, it is returned to the patient's body through another tube attached to a second needle.

To remove the blood from the patient's vessels, a surgeon must create an "access" in the arm that can be used for repeated blood cleansing three times a week. The access is created by connecting a vein and an artery together, called an arteriovenous fistula (AVF). The AVF may not be used for dialysis treatment until six weeks or longer, during which time the vein grows tough and thick enough to withstand penetration with the dialysis needle.

If a person's blood vessels are too fragile or too small to create an AVF, the surgeon may create an arteriovenous graft (AVG), which is made from synthetic tubing used to connect the artery with the vein. Blood flow from the artery goes through the graft and then to the dialysis machine. Blood is returned to the body through the vein, similar to the AVF. This type of dialysis graft may be used under certain circumstances within two weeks of surgery.

The dialysis nurse will disinfect the skin prior to inserting the needles into a fistula or graft for the treatments. The needles are taped in place and are connected to the dialysis machine for the three-to-four-hour treatments. The needles are removed after each treatment session. Pressure will be held over the site until the bleeding stops. The spot will heal where the needle entered the fistula or graft. At the next dialysis treatment, the nurse will insert the needle into a different spot, at least half an inch away from the previous puncture. The dialysis staff will inspect the skin and access for signs of excessive bleeding, bruising of the tissues, infection, swelling, clotting, or lack of blood flow. These complications can be warning signs that a doctor's examination may be needed in order to save the dialysis access for future dialysis treatments.

The access is considered the lifeline for the dialysis patient. If dialysis is needed urgently or immediately, the surgeon will place a temporary catheter directly into a large vein in the neck to be used for treatments. The catheter has a greater risk of infection than a permanent access in the arm. Because the temporary catheter is not a long-term solution, an access in the arm will be placed as soon as possible.

If an AVF/graft is inserted, tight sleeves, watches, or bracelets should never be worn over the graft or fistula. Patients should never carry purses or shopping bags, sleep on the access, or have blood pressures measured in the arm with the access. They need to protect the access from any type of activity that could reduce the blood flow through it. The access should never used for other treatments such as the introduction of intravenous fluids or to take blood samples.

An uncommon but serious problem can be coldness, tingling, numbness, aching, weakness, or bluish discoloration of the hand, indicating that not enough blood flow is getting to the hand. The dialysis access may be "stealing" blood flow from the hand. If that occurs, a surgeon will need to perform a minor operation to restore more blood flow to the hand. The dialysis treatments can then continue using the fistula or graft.

Patients should follow the doctor's recommendations for diet and fluid restrictions between dialysis treatments. A dietician will teach patients what they need to know about eating less protein, restricting salt intake, and drinking a safe amount of fluid. This will make treatments easier and help patients feel better. Most patients take vitamin and mineral supplements. It is also important to take all medications as prescribed by your doctor.

Doctors, nurses, pharmacists, social workers, and dieticians will all form a partnership with patients on dialysis treatments. They can help reduce the side effects of nausea, dizziness, low blood pressure, cramps, or headaches during treatments. Changes in the dialysis time, sodium, or fluids can be made for each patient's special needs. Staff will make the treatments as comfortable as possible, and lab tests are taken monthly to ensure that patients are receiving the proper amount of dialysis.

The patients may have to make changes in their daily life which involve work, family, friends, and activities. Some patients choose to have their treatments at home rather than in a dialysis center or hospital. A dialysis-care partner can be trained to assist the patient at home, which must be equipped with enough space for the equipment, water, and adequate electricity to operate the dialysis machine. Members of the health-care team will partner with the patient to help make decisions about those daily changes in lifestyle.

Patients will need dialysis treatments for the rest of their life unless they are able to receive a kidney transplant. A kidney transplant is not for everyone, and most recipients of a kidney must undergo temporary dialysis. Dialysis remains the lifeline to keep a person well and help him or her maintain an active lifestyle. There are many resources for additional information; The Kidney Foundation www.kidney.org; American Association of Kidney Patients www.aakp.org; or American Kidney Fund www.akfinc.org.