Last week we talked about the process of dialysis. We went further to talk about how blood leaves and returns to the patient’s body. These two actions—removing and returning of blood—need to happen at the same time. That led us to the topic of blood access. We explored dialysis catheters and how patients and friends and families should help us keep them safe and keep infections at bay.

Let us turn our attention to one more type of blood accesses.

Arteriovenous Fistulae (AVF)

We simply call it a fistula. A fistula is a word used to refer to any connection between two cavities or organs. For example, in childbirth, some accidents may happen and there is an abnormal connection between the birth canal and the rectum. This is called a rectovaginal fistula. See, a fistula gets its name depending on which two organs or cavities are involved.

Therefore, an arteriovenous fistula is a connection between an artery (arterio) and a vein (venous). What happens is that surgeons create a connection between arteries and veins of the arm or in some special cases the legs, to provide a large blood vessel which can be used during dialysis.

The idea is that because arteries carry blood from the heart, they have a high pressure. Veins have a lower pressure as they carry blood back to the heart. When the high pressure of the arteries is joined to a vein, it makes that vein to enlarge and have high pressure which is then capable of withstanding constant use during dialysis. Remember we said in last week’s blogpost that dialysis happens with the aid of a blood pump. This pump supports extremely high speeds and thus the fistula must be able to handle that.

How to Care for A Fistula

For starters, there is a rigorous preparation needed for the creation of a fistula. In the UK for example, there is a special renal nurse called a vascular access nurse who helps in preparation of the patient and family for this. This is because there is an active kidney clinic for all patients with early stages of chronic kidney disease.

Patients are able to know in advance that soon they will start dialysis in a matter of months. This helps them to be prepared albeit to a small degree about what it will involve. Part of this is the creation of a fistula.

The arm is selected depending on how healthy the veins and arteries look. That means we do a scan (ultrasound scan) of the arms. The surgeon will go for the artery and vein that looks healthy enough. Sometimes due to conditions like Diabetes Meliitus, veins and arteries become hardened and therefore may not be used for the purpose of fistula creation.

The surgery is done under some regional anaesthesia. That means that though you will be awake during the procedure, you will not feel pain. The arm will be numb. After the surgery you will be given some painkillers should you need them. You should expect to feel a buzz when you touch the part where the fistula was created.

The buzz is very important as it tells us that the artery is transmitting its high pressure to the vein. In short, the buzz reassures that the fistula creation was successful. It is important to carry out arm exercises like clenching and releasing the fist so as to encourage the fistula to mature.

Maturation of the fistula takes about six weeks. Maturing means that the blood vessel can be seen on the surface of the skin as a raised big vein. The buzz is strong, and nurses can hear that buzz through a stethoscope.

You should not however let anyone take a blood pressure reading or even take a blood sample from the fistula arm. This will easily cause bleeding of the fistula and destroy it. That arm should also not carry or lift heavy objects. I have no clear definition of how heavy is actually heavy for individual people.

The fistula is considered the best form of blood access in dialysis. It is important for us to note that unlike in a catheter, the rate of infections with a fistula is very minimal. It also causes better clearance of wastes during dialysis because it supports higher pump speeds than the catheter. Patients are allowed to bathe, shower or even swim because there is no worry of any dressing getting wet.

The fistula is so important that the nurses I had mentioned earlier called vascular access nurses make it a point to keep doing scans on the fistula at various intervals to make sure that it is in perfect shape all the time.

Concerns with Fistulae.

Like everything else, nothing is always perfect A fistula can bleed during or after dialysis. This is a potentially fatal event. The blood flowing through the fistula is at a high pressure so the bleeding can easily lead to loos of consciousness if not death.

Due to various reasons, some fistulae may stop working necessitating the uncomfortable need for another one. This is why it is vital to keep feeling that fistula for a buzz feeling. If the buzz reduces in intensity it is important to let the kidney nurses know.

Some fistulae cut off blood supply to the rest of the arm and this can cause among other things swelling, pins and needles feeling or even the fingers may turn blue, purple or dark. The colour depends on your natural complexion. Should this happen, urgent surgery to repair that is carried out. This happens within the shortest time frame to avoid losing the function of the affected arm altogether.

Conclusion

Even with these concerns, a fistula is still the recommended type of blood access in dialysis. Its benefits outweigh the risks. The only problem in Kenya is that almost all patients start dialysis as a n emergency. Therefore, they have no time to have fistulae created in advance. We also have not sensitized the public on the reality of kidney disease and the benefits of dialysis for those that will need it.

It is important that clinicians do not shy away from telling patients the accurate staging of their kidney disease. This way, the conversation of ‘What Next’ can begin soon enough.

Yet it is my prayer that this blogpost will help you to understand a little about blood access in dialysis.