Overview of Dialysis Fistula
Creating a dialysis fistula is a common procedure for patients dealing with severe kidney disease or end-stage renal disease (ESRD). This surgery provides a permanent point of access for them to receive ongoing blood-cleaning treatment, called hemodialysis. The perfect dialysis fistula allows a fast enough blood flow for effective dialysis, can be accessed repeatedly, lasts a long time, and has few complications. In the United States, over 400,000 people are treated with this form of dialysis each year, at a cost of about 90,000 dollars for each patient.
There are many methods for providing permanent dialysis access, but the one that’s been shown to have the most advantages in terms of health benefits and cost is the arteriovenous fistula (AVF) technique. Like a bridge, this method connects an artery directly to a vein. Guidelines from the National Kidney Foundation suggest this technique as the first choice for hemodialysis patients with severe kidney disease, before considering other methods like synthetic grafts or hemodialysis catheters.
Research has shown that arteriovenous fistulas are associated with a significant drop in negative outcomes like infection rates, hospital admissions, catheter failure, narrowing of the central veins, and even death. It also comes with a lower overall cost compared to other methods. While it can’t be used immediately because it takes time to mature (like a fine wine), arteriovenous fistulas have a high success rate and can last anywhere from 3 to 5 years, whereas synthetic grafts usually only last 1 to 2 years.
In the rest of this document, we’ll discuss the relevant body parts involved in creating a dialysis fistula, reasons to do the surgery and reasons not to, the details of the procedure, and potential complications.
Anatomy and Physiology of Dialysis Fistula
An arteriovenous fistula is a passage that is made by a surgeon that connects an artery, a blood vessel that carries blood away from the heart, and a vein, a blood vessel that carries blood towards the heart. This procedure is often used for people who require regular dialysis, a medical treatment for kidney failure that removes waste and excess water from the blood.
The process by which an arteriovenous fistula matures is called venous arterialization. During this process, the wall of the vein changes due to the release of a gas called nitrous oxide and the breakdown of a protein called elastin, which allows the vein to expand. A fully matured arteriovenous fistula is easier to insert a needle into regularly and provides the fast blood flow needed for dialysis treatment.
To determine if an arteriovenous fistula has matured enough, doctors use the “Rule of 6’s”. This rule states that 6 weeks after the fistula is created, it should achieve a blood flow rate of at least 600 ml/min, a width of at least 6 mm, and a length of 6 cm for needle insertion, with a depth of 6 mm or less from the skin surface.
To create an arteriovenous fistula successfully, it’s important for surgeons to understand how the blood vessels in the upper arm work. The brachial artery is the main artery that goes down the arm and splits into the radial and ulnar arteries at the elbow. The radial artery is a branch that goes down the forearm to the wrist. The cephalic vein is a surface-level vein that starts at the hand and runs along the arm of the forearm, ending at the shoulder.
Finally, the basilic vein is a deeper vein that also starts from the hand, traveling up the arm and emptying into a larger vein called the brachial vein, before joining the axillary vein. The blood in these larger veins eventually enters the superior vena cava, a major vein that directs blood into the heart.
Why do People Need Dialysis Fistula
If you have an advanced stage 4 chronic kidney disease, which means your kidneys are only working at less than 30% of their normal function, or if you urgently need regular dialysis treatment, it’s important that you are educated about kidney failure. Your medical team should talk to you about different treatment options, which include receiving a kidney transplant, undergoing a surgical procedure called peritoneal dialysis, receiving hemodialysis (a treatment that helps your blood get rid of waste and extra fluids when your kidneys can’t do this job properly), or simply managing the disease with medication and lifestyle changes.
If you have chronic kidney disease stage 5, it means your kidneys are only working at 10 to 15% of their normal function. You will need regular dialysis treatment that helps manage your body’s levels of acid and minerals, controls blood pressure, and helps your body eliminate waste products. Your kidney specialist or nephrologist will help determine what kind of dialysis is best for you. If the chosen method is hemodialysis, a vascular surgeon will perform a procedure to create an arteriovenous fistula. This is a connection created surgically between an artery and a vein that allows high blood flow so that your blood can be cleaned and returned back to your body during dialysis.
When a Person Should Avoid Dialysis Fistula
There are some situations where a doctor cannot create a dialysis fistula, which is a way to access the veins for kidney dialysis. Conditions that can prevent this from happening include: blockage in the veins, having had an amputation, or severe peripheral artery disease (a condition where blood vessels outside your heart get narrowed down or blocked) with tissue death on the side where the doctor was planning on creating the dialysis fistula.
Moreover, there are circumstances where creating a dialysis fistula might not be the best option but it is not absolutely prohibited. These conditions include having a pacemaker, narrowing of the central veins, an active infection, or if you’ve undergone surgery where your armpit lymph nodes were removed (axillary node dissection). People who are older, those with severe heart failure, or those with a short life expectancy are also seen as high risk.
Equipment used for Dialysis Fistula
For a doctor to successfully conduct a vascular operation – a surgery involving the blood vessels – they need specific instruments at hand. These tools include, but are not limited to, scalpels (sharp knives for surgery), needle holders (devices to hold the needle), tissue forceps (tongs-like tool to hold or move tissues), scissors, self-retaining retractors (tools that hold back tissue or organs to improve visibility), vessel loops (flexible loops for holding or pulling back blood vessels), bulldog clamps (clips that temporarily close off a blood vessel), and vascular clamps (devices to control blood flow during surgery).
Different surgeons may prefer different types of vascular clamps. The main type of thread utilized for connecting blood vessels, known as a vascular anastomosis, is usually a monofilament non-absorbable suture. This means it’s a type of thread that doesn’t get absorbed by your body over time.
Fundamental to the procedure too are suction devices and electrocautery tools. These are used to remove excess fluids and cut through or seal off tissue with heat respectively. Moreover, a Doppler ultrasound – an imaging method that uses sound waves to examine the movement of blood flow – should be accessible during the whole surgery. This ensures that the surgeon can regularly make sure that there is an open path for blood to flow (patency) and that it’s flowing effectively.
Who is needed to perform Dialysis Fistula?
Creating a dialysis fistula, which is a special connection created in your blood vessels to allow you to have dialysis, should be done by a surgeon who has a lot of experience in vascular surgery. Vascular surgery involves operating on blood vessels. It’s not just the surgeon who’s involved, though. Several other medical team members are necessary for the procedure.
This team usually includes the main surgeon, a first assistant who helps the surgeon, an anesthesiologist (this is the doctor who will put you to sleep during the procedure), a scrub technician who helps in preparing for the surgery, and a circulating nurse who helps move things along smoothly in the operating room.
This group of professionals will ensure that the creation of your dialysis fistula goes as planned and is safe for you.
Preparing for Dialysis Fistula
When planning to create a dialysis fistula – a special type of surgical connection between an artery and a vein – doctors need to carefully choose the right patient. They do this by getting a detailed medical history and doing a physical exam. They look at important factors like whether a patient has a heart device known as an Automatic Implantable Cardioverter-Defibrillator (AICD) or pacemaker, whether they’ve had breast surgery or surgery in the armpit, or if they’ve had any previous medical procedures that involved the veins.
They also examine the veins closely, measure the blood pressure, check if the pulse is textbook “symmetrical” (the same) in both arms, and perform an Allen test. This test makes sure the arteries in the hand are working well and in good condition.
To create a long-lasting AV (arteriovenous) fistula, a patient’s vein structure becomes a key determinant. An ultrasound imaging technique, called duplex ultrasound, is used to examine the veins. Guidelines suggest an ideal vein should be 2.0 mm to 2.5 mm wide, have a 6 cm segment for the needle insertion, and have freely flowing central and draining veins. Additionally, it’s generally advised to create the access point as far away in the upper arm as possible, preferably on the non-dominant arm so as to preserve central access in the future.
There are different methods for creating a dialysis fistula, but the first choice is usually an autogenous AV fistula. This is a connection made using the patient’s own blood vessels and is the highest standard treatment for kidney dialysis patients. However, some patients might not benefit from this: older patients with smaller veins, people with poor vein quality (because of hardened veins or diabetes), people with slowly worsening kidney disease, or those in poor general health and/or have short life expectancy.
Finally, doctors always consider patient preferences, their lifestyle, expected lifespan, and quality of life when planning the best way to create the dialysis access point. The approach is always centered on the patient’s welfare.
How is Dialysis Fistula performed
Creating dialysis fistulas, which are connections between arteries and veins, requires choosing a suitable location based on the patient’s blood vessel arrangement. The patient lies flat on their back with their chosen arm fully extended, and then the area is cleaned and covered properly for sterility. The key principles in creating these connections are to have full control over the blood vessels, both where they start and where they end, and making sure the connection is not too tight or twisted.
There are different types of these connections:
Radiocephalic Fistula: This method links the cephalic vein, which runs up the outside of your arm, to the radial artery in your wrist. A small cut is made on the wrist, and the artery and vein are separated, moved around, and secured. If there are any small veins attaching, they can be tied off and cut away. The artery is then cleaned with a special saline solution. The vein is then connected to the artery either by connecting the end of the vein to the side of the artery or by creating a small hole in the vein and connecting it to the artery. This connection is then sewn up with a permanent, non-absorbing stitch. After the procedure, a Doppler ultrasound is used to make sure the connection is working well, and the wound is stitched up.
Brachiocephalic Fistula: This method is similar to the one above, but it connects the cephalic vein to the brachial artery in your upper arm. The procedure remains pretty much the same, starting with a small cut made over the inside of your elbow. After the procedure, a Doppler ultrasound is used to check the connection’s functioning, and then the wound is stitched up.
Transposition Brachiobasilic Fistula: This method is used when the above techniques aren’t possible or have failed. The basilic vein is deeper and on the inside part of your arm, so it needs to be relocated to a more superficial and outside location. This can be done in one or two stages. The two-stage approach is more efficient but requires further treatment and more time before use.
One-Stage: A cut is made in the upper arm over the basilic vein. The brachial artery and basilic vein are revealed, moved around, and secured. A special tool is used to create a path along the front of the upper arm. The end of the basilic vein is first cut and sewn up laterally, and an end-to-side connection is then made.
Two-Stage: Similar to the One-Stage method, the first stage involves creating a small cut to connect the brachial artery with the basilic vein. After this connection is allowed to mature for 6-8 weeks, a second procedure is done with a curved tunneler to cut, move, and reconnect the basilic vein using the same careful stitching.
Possible Complications of Dialysis Fistula
Like all surgeries, there’s a chance of bleeding, infection, or harm to nearby body parts. People who are already at high risk may face a higher chance of issues that can lead to more health problems. These risks can be immediate (right after surgery), early (days to months later), or late (once the body has fully healed).
Immediate issues can include things like bleeding, swelling, or a sudden blood clot causing loss of sensation at the surgical site. Early problems might be restrictions in the blood flow, blood clots, infections, high blood pressure in your veins, or trouble with the healing process. Late complications can include problems like an oversized blood vessel (aneurysm), restricted blood flow, delayed blood clots, infections, or nerve damage.
The most common complications that can happen with dialysis fistulas and might need surgery are an oversized blood vessel, infection, blood clot, restriction of the central vein, decreased blood flow to the hand or arm, and failed healing process. Let’s break this down:
Aneurysm can occur when the repetitive needle pricks in one area weaken the blood vessel wall or because of high-pressure blood flow over time. These will usually need surgery if the skin starts getting damaged or if no other place can be used for needle insertion. If a high-risk aneurysm is not treated, it can break and lead to dangerous blood loss.
Infections of the AV fistula (a direct connection between an artery and a vein) often show as redness, swelling, and possibly signs of infection throughout the body. Localized infections can usually be treated with the right antibiotics, but more serious infections might need surgical treatment to drain out the infected area.
Thrombosis, or blood clots, is the most common complication and typically occurs in areas with restricted blood flow, either where the blood vessels join or in the vein itself. The risk of this increases with the level of restriction. In comparison, fistulas have a lower chance of blood clots than grafts.
Central venous stenosis is a restriction of the central vein which can lead to high blood pressure in the veins causing swelling. This might limit movement and is often caused by the insertion of veins and devices in the central vein. Signs can be reduced quality of dialysis, trouble with inserting needles, pain in the area, or increased venous pressure.
Ischemic steal syndrome is when there’s decreased blood flow in the hand or arm after creating the AV fistula. This can lead to pain, reduce motor function or sensation, or nerve damage. Fistulas in your forearm have a lower chance of developing this, and it is even lower when using fistulas instead of grafts.
One common reason for a fistula not healing well can be due to a stricture, which is when there’s a significant decrease in the size of the blood vessel. Older patients, or those with health problems such as high blood pressure, diabetes, obesity, heart failure, or peripheral atherosclerosis (hardening of arteries), are at a higher risk. In some cases, further surgery may be needed to fix it.
What Else Should I Know About Dialysis Fistula?
Hemodialysis is a common treatment for patients with ‘End Stage Renal Disease’ (ESRD), which means severe kidney failure where they no longer work well enough to meet the needs of daily life. It helps clean the blood when the kidneys can’t.
In this treatment, one method is creating an ‘Arteriovenous fistula’ – a connection made by a surgeon between an artery and a vein in your arm. While this method takes longer to get ready for use, it actually has less risk of infection, less chance of needing hospital stays, and lower chances of a condition called ‘central venous stenosis’ (narrowing of a large vein near the heart). Also, there is a reduced risk of death when this is compared to using synthetic grafts or dialysis catheters (a type of tube inserted into a large vein for dialysis).
