An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein designed to provide reliable, long-term access for hemodialysis treatments. This procedure is performed for individuals with end-stage renal disease who require regular blood filtration. Placing the fistula in the upper arm (brachiocephalic or brachiobasilic) is preferred due to the larger diameter of the vessels. Using native blood vessels in the upper arm contributes to greater durability, lower complication rates, and improved blood flow compared to other access options like grafts or catheters.
Surgical Creation and Maturation
The creation of an upper arm fistula involves connecting an artery, such as the brachial artery, to a nearby vein, typically the cephalic or basilic vein. This connection, known as an anastomosis, reroutes high-pressure arterial blood flow into the lower-pressure vein. This surge of arterial pressure fundamentally changes the vein’s structure.
The vein must undergo “maturation” before it can be used safely for dialysis. Maturation is the biological response where the vein wall thickens and the vessel diameter enlarges under the constant, increased pressure from the artery. This transformation makes the vein robust enough to withstand the repeated needle insertions and high flow rates required during hemodialysis sessions.
This waiting period typically takes several weeks to months, often ranging from six to eight weeks, but sometimes longer. During this time, the vein develops the large, firm structure needed to ensure efficient toxin removal and minimize the risk of complications. The fistula cannot be used immediately after surgery, and patience is necessary while the vessels mature.
If the basilic vein is used, the procedure may be done in two stages because this vein lies deeper beneath the skin. The first stage involves creating the connection between the brachial artery and the basilic vein. After the vein has matured, a second procedure is often performed to “transpose” or move the vein to a more superficial position, making it accessible for cannulation.
Daily Management and Protection
Daily assessment of the upper arm fistula is necessary to ensure its continued function. The two most important signs of proper blood flow are the “thrill” and the “bruit,” which should be checked every day. The thrill is a distinct vibration or buzzing sensation felt by gently placing fingers over the fistula site.
The bruit is the characteristic whooshing or swishing sound of blood rushing through the connection, heard by placing an ear or a stethoscope over the fistula. Both the thrill and the bruit confirm that the high-flow connection remains open and is working. Any noticeable change, such as a weaker thrill or a different sound, warrants immediate contact with the care team.
Protecting the upper arm fistula from compression or trauma is important for long-term function. Patients must strictly avoid having blood pressure cuffs placed on the fistula arm, as the pressure can damage the vessels and lead to clotting. All blood draws and intravenous (IV) line insertions should be performed on the opposite arm to prevent injury.
Avoid wearing tight jewelry, watches, or clothing with restrictive sleeves over the fistula site, as this can impede blood flow and cause clotting. It is also important to prevent prolonged pressure on the arm, meaning patients should avoid sleeping directly on the fistula arm. Routine hygiene involves gently washing the area daily with mild soap and water to reduce the risk of infection.
Identifying Complications
Several complications can arise with an upper arm fistula, and recognizing their signs early is necessary for prompt intervention. Thrombosis, or clotting, is a common issue, signaled by the sudden loss of the thrill and bruit. Since the loss of these signs indicates that blood flow has stopped, this situation requires emergency medical attention.
Infection is another concern, typically presenting as localized warmth, increasing redness, swelling, or pain around the fistula site. Pus or discharge from old needle holes or a fever and chills can also signal an infection requiring antibiotic treatment. Aneurysm formation, a localized bulging or ballooning of the vein wall, can develop over time due to repeated cannulation or high pressure.
A complication known as “steal syndrome” occurs when the high-flow fistula diverts too much blood away from the hand and fingers, causing ischemia or lack of adequate blood supply to the distal limb. Symptoms of steal syndrome include coldness, paleness, numbness, or pain in the hand and fingers, which may worsen during dialysis. These symptoms can range from mild discomfort to severe pain and tissue loss, and any persistent sign of distal ischemia should be reported immediately to a healthcare provider.