As kidney function deteriorates, you need to replace the role of the kidneys - ‘renal replacement therapy’. A kidney transplant is best, but if there isn’t a transplant option, or you are awaiting a transplant, dialysis is necessary. This can be peritoneal dialysis or most commonly haemodialysis. 

In haemodialysis, blood is removed via a blood vessel (vascular access), passes through the dialysis machine which removes impurities that have built up in the blood, and this clean blood is then returned to your bloodstream. The gold standard and most reliable form of blood vessel for vascular access for haemodialysis is a fistula. A fistula usually lasts longer than other forms of vascular access, they rarely have infection problems and because they have high blood flow, they remove more impurities in shorter time and so allow for a more effective dialysis. 

So what is a fistula? 

A fistula enables haemodialysis to take place. Normal veins used for blood tests are not strong enough for dialysis because blood is pumped through the dialysis machine at high speeds. Somehow, we need to create a ‘stronger’ blood vessel. We do this by connecting a vein to an artery either in the wrist area or upper arm. When this connection is created, fast flowing blood from the artery travels up the vein. The vein adapts to this by gradually thickening up and enlarging and turns into a ‘super-vein’. At this point the fistula is strong enough to withstand needling on a regular basis and allows for regular dialysis. 

Unfortunately, we can’t make a fistula for everyone. There must be a suitably sized vein and artery in the arm and we work this out by examining your arm and ‘mapping’ the arteries and veins with ultrasound. In some people the vein or artery in the arm is not big enough for a fistula. Also, veins in the arms may be damaged by previous blood tests, or by the insertion of IV lines. All patients with kidney disease are advised whenever possible, to protect the blood vessels in their arms 'Save Your Vein!'. Whenever possible it is best to have blood taken from the back of the hands. 

The operation to connect the artery and vein lasts about an hour. It is done under local anaesthetic so you are awake, can chat with the surgeon and I always listen to music in theatre – sometimes the patient sings along! Once the fistula is created, there will be a ‘buzz’ in the vein. You will be shown how to feel this buzz and it is your way of making sure the fistula is working.

 Usually, fistula surgery is done as a ‘day-case’ meaning you will go home on the same day. occasionally you will need a General Anaesthetic and if this is the case, you will be given information on what to bring with you to the hospital and you will be asked not to have anything to eat or drink from midnight before you come in. You can take all your medications as usual, including blood thinning medicines such as aspirin or clopidogrel. If you are on warfarin, you will be given separate instructions. 

How do you care for the fistula? 

After the operation there are a couple of ‘do’s and don’ts’ to allow the fistula to develop. Drink enough to keep well hydrated, and if you are already established on dialysis, the dialysis nurses will not remove too much fluid from you. Also, don’t carry the straps of a bag over your arm as the fistula might get compressed. 

If the ‘buzz’ disappears, then please alert your dialysis nurse or doctor. There are rescue procedures that can be done to restore flow in the fistula.

If the site of the fistula operation becomes red, hot or swollen, this may be the sign of a wound infection and you should see your doctor. Occasionally too much blood flow is diverted to the fistula and the hand might become cooler or you might experience ‘pins and needles. If you notice this, please tell your doctor. 

For a few days after the fistula operation, it is a good idea to elevate the arm whilst relaxing at home and not use your arm for lifting heavy bags or weights. Once the wound is fully healed and the fistula is working well, there are no restrictions and you can use your arm as normal. For the first 3 weeks after the operation, avoid heavy sport and exercise - you should be able to drive a week after surgery. 

A fistula formation is generally a very safe operation. The most common complication is that the fistula doesn’t mature. 

Approximately 30% of fistulas will not work either within the first 24 hours or so after the operation, or they will clot off or fail to develop suitably to be used for haemodialysis. If this happens, you may need a second operation or another procedure to re-establish the flow in the fistula. 

When can my fistula be used for dialysis? 

The fistula usually takes about 6 weeks to ‘mature’ and at this point it is ready to be ‘needled’ for dialysis. When first used, the walls of many fistulas are often soft and mobile and so inserting the needle for the first few haemodialysis sessions may be a little tricky and bruising can occur at the site of the puncture. This is not unusual and whilst the bruising may look alarming, it usually settles within a few days. The nurse is then able to make a further attempt at inserting the needle. Over time, the vessel will become more fixed in position and the vessel wall thickens, meaning fewer problems when the needle is inserted.

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information from an article from Kidney Life Magazine Autumn 2022

Written by Jeremy Crane MD FRCS (vasc)
Consultant transplant and vascular surgeon at the Hammersmith Hospital West London.