Why is surgery needed?
People with chronic kidney disease may be kept well with dietary restrictions and drugs in many cases. If the disease becomes very advanced, then these treatments are no longer adequate. In this case, treatment is required to replace some of the functions of the kidney (this is called “renal replacement therapy” or RRT for short). Two types of RRT are continuous ambulatory peritoneal dialysis (or CAPD for short) or haemodialysis. In your case, the doctor has decided that RRT can be best provided by haemodialysis.
What is haemodialysis?
Haemodialysis is a treatment that involves taking blood out of your body through a needle and purifying it by passing your blood through a dialysis filter, before it is returned to your body. The filter removes the waste products and excess fluid that can build up because your own kidneys are no longer removing them efficiently. The machine allows blood to flow on one side of a semi-permeable membrane (one that will allow only certain substances to cross it) while the cleaning fluid flows on the other. This creates a gradient down which waste products can flow out of the blood in a similar manner to the way your kidney works.
How is dialysis managed?
To have dialysis, it is necessary to pump your blood at quite a high flow rate through the kidney machine for 3-5 hours at a time. The best way to do this is to place needles (large enough to allow high flow) into one of your blood vessels. The easiest way to allow this is to create an arteriovenous fistula. This is a “short circuit” in your circulation, and will allow the high blood flows needed in veins near the skin. The veins get a lot bigger as a result of the high flows. They can then have needles put into them easily without damaging the important arteries and veins lying deeper within your body.
How is the site for my operation chosen?
The doctor will examine you for suitable veins and arteries. This may involve only clinical examination. Sometimes a more detailed ultrasound examination of your blood vessels is required. This is painless and takes about 40 minutes. Very occasionally it may be necessary to perform a venogram to identify suitable veins. This involves placing a fine needle in your blood vessels and injecting material that gives a more detailed X-ray picture before deciding on the best place to site your fistula. Your doctor will advise you if any of these tests are needed.
The most common site for a fistula is at the wrist. A vein and artery are joined together through a small cut in the forearm.
This is usually done under local anaesthetic and you may be able to go home the same day. Doctors will try and site the fistula on the opposite side to the hand you use most (ie. on the left in right handed people and vice versa).
Sometimes they are placed higher in the arm or in the leg if that is where the most suitable veins are to be found.
Can my new fistula be used immediately?
Unfortunately a new fistula cannot be used immediately. They need time to enlarge. This can take up to six weeks. Once the fistula is big enough to allow dialysis needles to be placed in it, then it can be used.
Not all fistulae will enlarge as needed. The success rate of the first operation is between 55% and 70%. This is because the veins are sometimes unable to enlarge enough. If this happens, then a duplex ultrasound scan will be performed. This can tell the medical team why the fistula has not developed properly. Further treatment may be needed, either another operation (usually under local anaesthesia like the first) or an angioplasty. Angioplasty involves passing a balloon down through a needle in the vein to stretch up any areas of narrowing in the fistula. This is done under local anaesthesia.
Over 8 out of 10 fistulae will work satisfactorily with one or two procedures.
What happens if my fistula does not work?
Occasionally a fistula will not develop adequately, despite careful surgery. In this situation, it is normal to try and place a further fistula higher in the arm through a small incision under local anaesthetic. Your doctor will explain where the fistula is to go and how the operation will be done.
Sometimes it is necessary to bring a deeper vein up to the skin (Basillic vein transposition). In this case, a longer cut is needed and you may require a general anaesthetic (ie. you will be asleep).
If no suitable veins are present in your arms, then you and your doctor may decide to use the veins in your leg. The vein on the inside of the thigh can be brought up near the skin and used as a fistula.
I have heard of people having artificial grafts for dialysis, why is this?
There are two reasons why artificial access grafts may be used. Firstly you may have no suitable veins, in which case a graft is used as a substitute. In other cases, there may be some urgency to provide access for dialysis. Grafts can be placed easily between arteries and veins and used for dialysis within a few days. This can be an advantage if dialysis is needed quickly.
If grafts can be used so quickly why are they not given to everyone?
Unfortunately grafts have problems. Although easy to insert they are more likely to fail than a fistula and are not as long lived. They are more likely to get infected, to clot and become blocked than a fistula made of your own arteries and veins. For these reasons fistulae are preferred. Grafts have an important role to play when it is either not possible or inappropriate to make a fistula. The most appropriate form of vascular access will be decided between you and your doctor. You will have the opportunity to discuss which operation is best suited to your needs before you come to surgery.
Does my fistula need special care?
It is important to look after your fistula (or graft) as it provides access for dialysis. This means keeping the skin clean and avoiding undue pressure over it. You will be able to feel it buzzing. If you notice that the fistula is no longer buzzing, then you must tell your dialysis unit immediately (ie. the same day), as it may require treatment if it has blocked.
Fistula can become infected, so any unusual soreness or redness around the needle sites should also be reported to your dialysis unit.
The dialysis team will measure the flow and pressures during dialysis to determine how your fistula is functioning. If they are concerned that it is not adequate, you may be asked to come for a further scan. If the scan shows any narrowing, then an angioplasty or further surgery may be required to keep it functioning properly. Your doctor will discuss this with you if it is necessary.
If you have any other questions about your fistula, please ask your doctor who will be happy to advise you.