Fistula – everything that you need to know
What is a fistula?
An arteriovenous fistula, or AVF, is a vessel that is formed by joining a vein to an artery in your arm during an operation to form an accessible blood vessel that gives increased flow of blood that are adequate for dialysis. The process of joining the vein to artery allows for an increase in the size of the vein as well as the flow in it, and this segment of the vein is called the ‘fistula’.
To carry out dialysis two needles are inserted into the fistula and after dialysis, the needles are removed. A fistula is the best vascular access for dialysis because it tends to have fewer problems and last longer than other types of dialysis access.
How should I take care of my fistula?
There are several things you should do to protect your fistula. Fistula is often called your ’lifeline’ because it is so important in enabling a good dialysis.
- Keep your fistula clean– although infections are less likely with a fistula they can still happen. wash your arm with soap and water daily and always wash it before dialysis.
- Check your fistula daily– the nurse will show you how to check for a pulse or vibration through your fistula or a sound (called a bruit). If you can’t feel it, you must contact your unit or renal ward the same day.
- Do not let anything obstruct the blood flow in your arm – do not allow your blood pressure to be taken on your fistula arm and do not wear constricting clothing or jewellery.
- Do not carry heavy shopping bags on your fistula arm. Avoid sleeping on your fistula arm.
Signs to look out for
Although a fistula is the best sort of access and is least likely to develop problems, you do need to be aware of problems that can occur so they can be acted upon quickly: –
- Bruising and swelling– if blood leaks out of the vessels and into the surrounding tissue it can cause bruising and the localised area to swell.
- Redness or heat– although infection is less likely to develop in a fistula this can still happen. Please contact your renal unit or renal ward immediately if you experience pain, redness, swelling at your fistula site
- Aneurysm – this is a swollen area which develops as a result of the vessel becoming weakened, usually because needles are repeatedly inserted in the same area. You may see aneurysms on fistulas that have been established for a long time. Aneurysms are less likely to develop if your needle sites are changed each dialysis (rope ladder) or if buttonhole needling is used.
- Steal syndrome– this is because your fistula the area below it of blood, it can cause your hand and fingers to feel cold and painful or numb. Occasionally, this can lead to more severe symptoms such as ulceration and inability to use the hand due to pain. If steal syndrome is going to occur, it usually develops soon after your fistula has been created.
- Reduction in fistula flow– check daily for the flow in your fistula by checking the ‘bruit’ and ‘thrill’. If either appears reduced or absent contact your renal unit or ward immediately. This can happen because of a narrowing in the vessel or because of a blood clot and will need to be treated quickly to try and keep your fistula working.
- Bleeding from your fistula– this can be an emergency if it occurs when you are not on dialysis, but such emergencies are very uncommon.
Another bleeding that you should look out for is blood oozing around your needles often on dialysis. Bleeding after dialysis or oozing slightly from your fistula at other times can mean that your vessel has narrowed and is increasing the pressure within the vessel. This may also cause a raised venous pressure reading on your dialysis machine; your nurses will explain where to look for this. Sometimes, the bleeding may be related to any ‘’blood thinning’’ medication that you may be taking, such as warfarin. If you notice any of these signs please let your nurses and doctor know so they can investigate. Most problems of this nature can be resolved to ensure your fistula keeps healthy.
- Allergies– If your fistula becomes red, itchy and sore after applying the anaesthetic cream or any cleaning agent or chlorhexidine, let your nurses know so an alternative product can be used. Also, let the nurse know if you have a reaction to the tape or plasters used.
Tests and investigations
- Recirculation and Access flow monitoring
- Ultrasound (often called Duplex or Doppler)
- Declotting of a fistula
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