An HD fistula, also known as an arteriovenous (AV) fistula, is a surgically created connection between an artery and a vein, typically in the arm. This procedure establishes an enlarged blood vessel that provides reliable access for hemodialysis treatments. Its purpose is to allow for the efficient removal and return of blood during dialysis, a process that cleans the blood when kidneys are no longer functioning adequately. This access point is recommended for individuals requiring long-term hemodialysis, offering a stable and durable pathway for this therapy.
The Need for Dialysis Access
Patients require dialysis access when their kidneys fail to adequately filter waste products and excess fluid from their blood, a condition known as end-stage kidney disease (ESKD). Hemodialysis is a medical procedure that performs the filtration function failing kidneys cannot. This treatment involves diverting a patient’s blood through an external machine called a dialyzer, which removes toxins and excess fluids before returning the cleansed blood to the body.
Hemodialysis demands a high volume of blood flow to effectively remove impurities. Without a specialized access point, repeated needle insertions into regular veins would cause them to collapse or become damaged due to the pressure and flow requirements of the dialysis machine. Therefore, a robust access site is necessary to ensure consistent and efficient blood flow for the machine to properly filter the blood. This access point allows for ongoing sessions of hemodialysis, needed several times a week to maintain the body’s internal balance and prevent the buildup of harmful substances.
Different Types of Dialysis Access
Several types of vascular access are used for hemodialysis. An arteriovenous (AV) fistula connects an artery to a vein, usually in the arm. This surgical connection causes the vein to enlarge and strengthen over time, providing a durable access point for repeated needle insertions during dialysis.
An arteriovenous (AV) graft uses a synthetic tube to connect an artery to a vein, typically in the arm or leg. This graft acts as an artificial vessel that can be cannulated for dialysis. Grafts can be used sooner than fistulas, often within 2 to 8 weeks after placement.
Central venous catheters (CVCs) are soft plastic tubes inserted into a large vein, usually in the neck, chest, or groin, leading to a central vein near the heart. CVCs provide immediate access for dialysis and are often used temporarily, such as when a patient needs to start dialysis before a fistula has matured. CVCs are not preferred for long-term use compared to fistulas or grafts.
How a Fistula is Created and Used
Creating an AV fistula involves a minor surgical procedure, performed in an outpatient setting, often in the non-dominant arm. A surgeon makes a small incision, usually near the wrist or elbow, and connects an artery to a nearby vein. This direct connection allows arterial blood, which is under higher pressure, to flow into the vein, causing it to expand and become thicker.
Following surgery, the fistula requires “maturation,” the time it takes for the vein to enlarge, strengthen, and develop sufficiently for regular use. This process can take one to four months, sometimes extending to 6 to 9 months. During this period, increased blood flow from the artery helps the vein’s walls thicken and its diameter increase, making it capable of withstanding repeated needle insertions for dialysis.
Once matured, the fistula is ready for hemodialysis. At the beginning of each session, two needles are inserted. One draws blood from the body to the dialysis machine, where it passes through a dialyzer that cleanses it of waste products and excess fluids. The purified blood is then returned to the body through the second needle, completing the circuit. This continuous flow allows for efficient blood filtration during treatment.
Living with a Fistula
Proper daily care of an AV fistula is important for its long-term function and to prevent complications. Individuals with a fistula should maintain good hygiene by washing the arm with the fistula daily with soap and water. Avoid wearing tight clothing, jewelry, or anything that could constrict the arm, as this can impede blood flow. Blood pressure measurements, intravenous (IV) lines, or blood draws should never be performed on the arm with the fistula to protect the access site from damage.
Monitoring the fistula’s function regularly is also important. A working fistula produces a palpable vibration, a “thrill,” and an audible whooshing sound, a “bruit.” Patients are instructed to feel for the thrill and listen for the bruit daily to ensure the fistula is functioning. Any changes in the thrill or bruit, such as their absence or a significant weakening, should be reported to the healthcare team promptly.
Signs indicating a problem with the fistula include swelling, redness, pain, or warmth around the access site, which could suggest an infection. Other signs include numbness or tingling in the hand or fingers, or a cold sensation, which might indicate issues with blood flow. Prompt communication with the dialysis care team about any of these symptoms is important for timely intervention and to maintain the fistula’s function.
Alternative Dialysis Access Options
If an AV fistula cannot be created, fails, or is not suitable, other options ensure continued access for dialysis. Peritoneal dialysis (PD) is a distinct form of dialysis that does not require vascular access in the arm. It uses the natural lining of the abdomen, the peritoneum, as a filter. A catheter is surgically placed into the abdomen, through which a special fluid is introduced to absorb waste products from the blood, which are then drained out.
For individuals who still require hemodialysis but cannot use a fistula, arteriovenous (AV) grafts serve as an alternative. These grafts, made of synthetic material, are surgically implanted to connect an artery and a vein, providing a pathway for blood flow similar to a fistula. While they can be used sooner than fistulas, they have a shorter lifespan and a higher chance of complications like clotting or infection. Central venous catheters (CVCs) are also utilized for immediate or temporary hemodialysis access. These soft tubes are placed into a large vein, usually in the neck or chest. While convenient for rapid initiation of dialysis, CVCs are used for shorter durations due to a higher likelihood of infection or other issues compared to fistulas or grafts.