Arteriovenous Fistula Health Article

Definition

An arteriovenous fistula (AV fistula) is the connection of a vein and an artery, usually in the forearm, to allow access to the vascular system for hemodialysis, a procedure that performs the functions of the kidneys in people whose kidneys have failed. Connecting the vein and artery is a surgical procedure. The fistula develops over a period of months after the surgery.

Purpose

The surgical creation of an AV fistula provides a long-lasting site through which blood can be removed and returned during hemodialysis. The fistula, which allows the person to be connected to a dialysis machine, must be prepared by a surgeon weeks or months before dialysis is started. When the vein and artery are joined, the vein gradually becomes larger and stronger, creating the fistula that provides vascular access years longer than other types of access and with fewer complications.

Sometimes dialysis is only needed temporarily, but some people need it for the rest of their lives or until a kidney is available for a transplant. When kidney failure is diagnosed, time is needed to prepare the patient's body with either an AV fistula or implantable devices that will connect the person to the dialysis machine.

Demographics

At any one time, the number of patients in the United States with kidney failure is approximately two million and rising. According to the National Kidney Foundation, by the year 2008, three million people will be expected to have what is known as end-stage renal (kidney) disease. These people can be of any age, from any background. They are typically suffering from another condition or disease that has led to kidney shutdown, and most will require dialysis. Among dialysis patients, over half will have an AV fistula as vascular access.

Description

Surgery to create an arteriovenous fistula is usually conducted using a local anesthetic, injected at the site of the proposed fistula. The procedure is performed in a hospital or one-day surgery center and can usually be performed on an outpatient basis if the patient is not already hospitalized. After cleaning and sterilizing the site, the surgeon will make a small incision in the forearm sufficient to allow the permanent joining together of a vein and an artery in the arm. The blood vessels will be appropriately blocked to stop blood flow for the procedure and incisions will be made to join them. Silk sutures, just as those used in other types of surgical incisions, will be used to close incised areas as needed after the vein and artery have been joined. Once joined, blood flow will increase, the vein will become thicker, and over a period of months the connection will become strong and develop into the fistula that will allow permanent vascular access.

Hemodialysis

Dialysis is performed as critical life support when someone suffers acute or chronic kidney failure. It is a mechanical way to cleanse the blood and balance body fluids and chemicals when the kidneys are not able to perform these essential functions. Because kidney function can be reversible in some cases, dialysis can provide temporary support until renal function is restored. Dialysis may also be used in irreversible or chronic kidney shutdown when transplantation is the medical goal and the patient is waiting for donated kidneys. Some critically ill patients, with life-threatening illnesses, such as cancer or severe heart disease, are not candidates for transplantation and dialysis may be the only option for treating what is called end-stage renal disease (ESRD).

There are two types of dialysis, hemodialysis and peritoneal dialysis. In hemodialysis, the blood circulates through a machine outside the body and is filtered as it circulates. In peritoneal dialysis, the blood is filtered through a membrane that has been placed in the abdomen. Blood remains in the body and waste material is filtered into an exchange fluid through an opening in the abdomen called a port. Only hemodialysis requires an AV fistula or other vascular access.

Hemodialysis circulates blood through a dialysis machine that contains a filter membrane. The blood is slowly pumped out of the body and into the machine for filtering. After being filtered, the blood is returned to the body through the same vascular access. About one cup of blood is outside the body at any given moment during the continuous circulation process.

Hemodialysis is usually done three times a week, taking between three and five hours each time. Healthcare professionals perform the procedure either at independent dialysis centers or in hospitals or medical centers. Dialysis patients must go to the hemodialysis center where they will sit to receive the treatment. Although they cannot walk around, they can watch television, read, or talk to other patients. The dialysis center offers patient education, including videos and brochures that describe treatment options and self-care. Patients can also be given advice and information about paying for this ongoing treatment through nationally sponsored programs that are available especially for dialysis patients. Often the dialysis center offers emotional support as well, letting people meet and talk with other people who have kidney problems. Some people prefer to perform their own dialysis by having a home dialysis machine. This requires that the dialysis patient and another person, usually a family member, take a three- to six-week training program to learn how to do the treatment.