A hemodialysis shunt, graft, or fistula provides vascular access for hemodialysis, a treatment that cleans theblood by removing wastes and excess water from the body.
Purpose
Kidneys remove wastes from the blood through the urine, regulate the amount of water and minerals needed by the body, and produce hormones. When the kidneys lose their ability to filter wastes and excess water from the blood, hemodialysis is required. During hemodialysis, the blood is circulated through a hemodialysis (artificial kidney) machine. Hemodialysis cleans blood similar to the way kidneys do. A vascular site, such as an arteriovenous (AV) fistula or graft, provides access for the removal and return of blood during hemodialysis. The patient's blood is removed and circulated through a machine that contains a dialyzer. The wastes and excess water from the patient's blood pass through the dialysis machine's membrane into the dialysate, and are then discarded. The dialyzed (cleaned) blood is returned to the patient's bloodstream.
Description
The patient is attached to the hemodialysis machine through several means. The most common method of providing permanent access to the bloodstream for hemodialysis is an arteriovenous (AV) fistula. An AV fistula is created surgically by connecting an artery to a vein, usually in the forearm. An AV fistula requires planning more than other kinds of access because it takes two to six months to develop. During this time, the stronger blood flow from the artery causes the vein to become larger. This allows the fistula to take repeated needle insertions, and for blood to flow quickly to the dialyzer. Another way to provide vascular access to the bloodstream is through an internal graft surgically connecting an artery to a vein with a synthetic or bovine graft placed under the skin. A hemodialysis graft does not need to develop as a fistula does and so can be used soon after it has been placed. Other types of vascular access, such as catheters and shunts, are temporary forms of access.
Complications
The primary complications of vascular access are clotting and infection. After an AV fistula has developed, it is less likely to form clots or get infected. Grafts typically have more problems with infection and clotting and need revisions or replacement sooner than fistulas. Proper hemodialysis depends on fistulas and grafts that work well.
To preserve and protect AV access:
Keep the access site clean at all times to prevent infection.
Avoid injections, intravenous (IV) needles or fluids, or taking blood samples in the access site arm.
Needle insertions for hemodialysis treatments should be rotated so that one spot is not repeatedly stuck and weakened.
Do not take blood pressure or put pressure on the access arm.
Advise patients to avoid wearing jewelry or tight clothing, sleeping on, or lifting heavy objects with the access arm.
Check the temperature and color of the fingers and thepulse of the access arm for adequate circulation.
Check for signs of infection at the access site.
Results
AV fistulas usually last longer and have less complications than other kinds of vascular access.
Health care team roles
The health care team can help patients prepare and maintain their vascular access. The type of vascular access selected for patients depends on their individual needs such as vein size. The health care team provides the information and support for patients and families on how to preserve and protect their vascular access.
KEY TERMS
Arteriovenous (AV) fistula—Surgical connection of an artery to a vein.
Bovine graft—Transplanted vein from a cow.
Dialysate—The cleansing solution used in hemodialysis.
Dialyzer—A part of the hemodialysis machine that contains two sections, one for the dialysate and one for the patient's blood.
Hemodialysis—The use of a machine to clean wastes from the blood when the kidneys cannot do it.
Hormone—A natural chemical produced by a part of the body to trigger or regulate particular functions.
Kidneys—Two bean-shaped organs that filter wastes from the blood and create urine.
Lameire, N., and R. L. Mehta, eds. "Complications of Vascular Access." In Complications of Dialysis. New York, NY: Marcel Dekker, Inc., 2000, pp. 1-27.
PERIODICALS
Biddle, G., et al. "Highlights for Nephrology Nurses from the Updated NKF-K/DOQI Guidelines." Nephrology Nursing Journal (February 2001): 45-50.
Butterly, D.W., and S. J. Schwab. "Dialysis Access Infections." Current Opinion in Nephrology and Hypertension (November 2000): 631-35.
Ross, E.A., et al. "Minimizing Hemodialysis Vascular Access Trauma with an Improved Needle Design." Journal of the American Society of Nephrology (July 2000): 1325-30.
ORGANIZATIONS
American Nephrology Nurses' Association. East Holly Ave., Box 56, Pitman, NJ 08071. (888) 600-2662. <http://anna.inurse.com/>.
National Institute of Diabetes and Digestive and Kidney Diseases. 3 Information Way, Bethesda, MD 20892.
National Kidney Foundation. 30 East 33rd St., New York, NY 10016. (800) 622-9010. <http://www.kidney.org>.
National Kidney and Urologic Diseases Information Clearinghouse. 3 Information Way, Bethesda, MD 20892.(800) 891-5390.
