Hemodialysis, the most common type of treatment for kidney failure, is a process that cleans the blood by removing waste and extra fluid when the kidneys can no longer perform this function. To accomplish this, a highly specialized, long-term vascular access point is surgically created in the patient’s body, which is most often located in the arm. This access must be robust enough to handle the large volume of blood flow required for the treatment, typically around 300 to 500 milliliters per minute, and withstand repeated needle insertions over many years.
The Preferred Method: Arteriovenous Fistula
The gold standard for long-term hemodialysis access is the Arteriovenous Fistula (AVF), created by a vascular surgeon connecting an artery directly to a vein. This surgical connection, called an anastomosis, forces the high-pressure, high-flow arterial blood directly into the lower-pressure venous system.
This intentional rerouting of blood flow causes the vein to undergo a process known as “maturation.” Over several weeks or months, the vein wall thickens and the vessel diameter enlarges under the constant exposure to higher pressure. A successful AVF must be allowed to mature before it can be used for dialysis, as this time is needed for the vein to become wide enough and strong enough to support the necessary blood flow and repeated cannulation with large needles.
The AVF is highly favored because it uses the patient’s own native blood vessels, resulting in the lowest risk of infection and blockage compared to other access types. Once mature, a well-formed fistula tends to last longer and requires fewer interventions to maintain its function. A surgeon typically creates the fistula in the non-dominant arm, often in the forearm connecting the radial artery and cephalic vein, or in the upper arm connecting the brachial artery and cephalic vein.
The Alternative Solution: Arteriovenous Graft
When a patient’s natural veins are too small, too weak, or otherwise unsuitable for creating a functional fistula, the next option is the Arteriovenous Graft (AVG). The graft is a surgically implanted synthetic tube, often made of a material like polytetrafluoroethylene (PTFE), that acts as the connection between an artery and a vein.
Similar to the fistula, one end of the graft is connected to an artery, and the other end is connected to a vein, creating the high-flow circuit required for dialysis. Because the graft is a synthetic tube, it does not require the same period of maturation as a natural vein.
This advantage means an AVG can generally be used much sooner, often within two to four weeks after placement, once the surrounding tissues have healed. However, the use of a synthetic material means the graft carries a higher long-term risk of complications. Grafts are more susceptible to infection and more prone to developing narrowing or blockages over time than a native fistula.
Protecting and Caring for the Access Site
Proper care of the access site is a continuous responsibility that directly affects the long-term success of both a fistula and a graft. Patients must check their access daily by gently feeling for a vibration or buzzing sensation, known as the “thrill,” which confirms that blood is flowing through the access. A change in the thrill, or its complete absence, can be an early sign of a blockage and requires immediate medical attention.
Strict precautions are necessary to prevent damage and preserve the access. No one should ever take a blood pressure reading, draw blood, or start an intravenous line in the arm containing the fistula or graft. These activities can compress the access or cause injury, leading to clotting or failure. Patients should also avoid sleeping on the access arm, carrying heavy objects over it, or wearing tight jewelry or clothing that might restrict blood flow.
Maintaining scrupulous hygiene is also a primary defense against infection, which is a major threat to the access. The skin over the access site should be washed daily with an antibacterial soap, and always before a dialysis session. Patients should be vigilant for signs of infection, such as redness, swelling, warmth, or any drainage from the site, and report them to their care team immediately.