Dialysis Access Procedures
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.
Your physician will first create an access portal, 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.
During dialysis, physicians use the dialysis access portal 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.
Types of Dialysis Access Procedures
Creating the access portal is a minor surgical procedure. There are two types of portals:
- Fistula, which your vascular surgeon constructs by joining an artery to a vein
- Graft, which is a man-made tube that your vascular surgeon inserts to connect an artery to a vein
Fistulas are typically 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.
For both fistulas, 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 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, you may need another fistula.
If you had a graft instead, you can usually begin using your graft in 2 to 6 weeks, when it is healed sufficiently.
Before choosing the access site, your surgeon may ask 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.
First, your doctor 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 doctor will give you the instructions you need to follow before the surgery, such as fasting. Usually, your surgeon will ask you not to eat or drink anything 8 hours before your procedure and 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, you 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. He 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.
If you cannot receive a fistula because the vein is too small or blocked, your surgeon may construct a graft using a tube of man-made material. Less commonly, he may choose to use a piece of a vein from your leg or a section of artery from a cow as alternative graft materials.
Your physician sews the graft to one of your veins and connects the other end to an artery. He may place the graft material straight or form a loop under the skin either in your lower arm, upper arm, or less commonly in your leg.