Dialysis is a medical treatment that takes over the function of failing kidneys, filtering waste products and excess fluid from the blood. During this process, blood is removed from the body, purified by a specialized machine, and then returned. To achieve this continuous, high-volume blood flow, a dedicated access point to the bloodstream is created. This access connects the dialysis machine to a patient’s circulatory system.
The Arteriovenous Fistula
An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein, typically in the arm. This reroutes high-pressure arterial blood flow into the vein, causing it to enlarge and strengthen over time, a process known as maturation.
Maturation usually takes several weeks to months, making the vein robust enough for repeated needle insertions during dialysis. The AV fistula is often the preferred option for long-term dialysis access due to its longevity and lower complication rates. It carries a reduced risk of infection and clotting compared to other access types, and its natural blood vessels provide efficient flow.
The Arteriovenous Graft
When a patient’s veins are not suitable for an AV fistula, an arteriovenous (AV) graft serves as an alternative. An AV graft involves surgically connecting an artery and a vein using a synthetic tube implanted under the skin.
Grafts can usually be used for dialysis sooner than fistulas, often within a few weeks of placement, as they do not require the same extensive maturation period. However, grafts tend to have a higher risk of complications compared to a well-matured fistula. These include an increased likelihood of infection and blood clot formation. Grafts may also be more prone to developing aneurysms.
The Central Venous Catheter
A central venous catheter (CVC) is a soft, flexible tube inserted into a large vein, typically in the neck or chest. This access is primarily used for immediate or temporary dialysis, such as in emergencies or while a fistula or graft matures.
Despite their immediate usability, CVCs are not preferred for long-term dialysis due to significant drawbacks. They carry a higher risk of infection because a portion of the catheter remains outside the body. Additionally, CVCs can lead to central venous stenosis, a narrowing of the vein that may limit future access options.
Deciding on the Best Access
The selection of the most suitable dialysis access involves a comprehensive evaluation by the healthcare team. Several factors influence this decision, ensuring the chosen access aligns with the individual’s medical needs and lifestyle. The patient’s overall health and existing medical conditions are carefully considered.
The condition of their veins and arteries is assessed to determine if natural vessels are suitable for a fistula or if a graft is necessary. The urgency of starting dialysis plays a role, as some access types require a maturation period. The patient’s lifestyle and anticipated duration of dialysis treatment also contribute. The final choice is a collaborative effort between the patient and their medical providers.
Maintaining Your Dialysis Access
Proper care of a dialysis access is important for its long-term function and to prevent complications. Maintaining good hygiene around the access site is important to minimize the risk of infection. Patients should avoid wearing tight clothing or jewelry on the arm containing the access, as this can restrict blood flow and potentially damage the access.
Protecting the access from injury is also important; patients should be mindful of bumps or cuts to the area. Blood pressure readings, blood draws, or intravenous (IV) lines are never performed on the arm with the dialysis access. Patients should regularly check their access for signs of proper function, such as feeling a vibration or “thrill” over the access. Any signs of complications, including swelling, redness, pain, warmth, or numbness, should be reported to a healthcare provider immediately.