The function of the kidneys is to filter the blood of toxins, control blood pressure and excrete urine. It controls the amount of water in the body by controlling the amount of sodium in the blood. It also produces a number of hormones, including erythropoietin which stimulates the bone marrow to make red blood cells.

The kidneys, two small bean-shaped organs that are about 5 inches long, are located on both sides of the spine, below the ribcage. Blood flow through the kidneys normally allows them to excrete wastes, concentrate urine, and conserve electrolytes (mineral salts). Any condition that significantly interferes with blood flow to the kidneys can result in renal failure. Renal failure is a decline in kidney function that occurs either suddenly (acute renal failure) or gradually (chronic renal failure).

The kidneys can be damaged via several mechanisms. The two most common causes of kidney failure are hypertension and diabetes. There are several other mechanisms of injury including atherosclerosis causing occlusion of the arteries to the kidneys, infection, immunologic factors and obstruction of the collecting systems.

When the kidney function has diminished to less than 10%, they can no longer support all of the functions that the body requires. This means that toxins and fluids can accumulate within the bloodstream. These can approach dangerous levels and become a threat to life.

To counteract this, patients can be placed on dialysis which allows for artificial filtration of the blood. Once committed to dialysis, patients will generally require sessions three times per week to clean the blood. One alternative to dialysis is a kidney transplant which is a good choice for healthy patients with a matching donor.

In order to receive dialysis, access to the blood stream must be created. This can be done in a variety of ways.

Treatment

Dialysis Access

Dialysis access is an entranceway into your bloodstream that lies beneath your skin and is easy to use. The access is usually in your arm or 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 circulate your blood through the machine to 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:

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 typically takes 3 to 6 months. Some fistulas 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, you may need another fistula.

You can usually begin using your graft in 2 to 6 weeks, when it is healed sufficiently. Usually fistulas are preferred to grafts 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.

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, causes these conditions. Your vascular surgeon will not place a dialysis access site in an area of the body with reduced circulation. 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 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.

Typically, this procedure is done on an outpatient basis. Most often, a patient will first be sedated and then a surgeon will numb the area where the fistula or graft will go. In some cases, an anesthesiologist may put you to sleep.

Depending upon the quality of your artery and vein, the 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 an artery and a large vein under the skin. The physician divides your vein and sews it to an opening made in the side of the artery. As a result, blood flows into the veins that lead back to your heart, and also down the arteries into the hand. The blood normally traveling 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.