Dialysis is a medical treatment that performs the functions of damaged kidneys, filtering waste products and excess fluid from the blood. This process becomes necessary when kidneys are no longer able to adequately clean the blood on their own. To connect a patient to the dialysis machine, a specialized entry point into the bloodstream, known as a dialysis access, is created. This access allows for the efficient removal and return of blood during treatment sessions. Understanding where these access points are located is essential for individuals undergoing or preparing for dialysis.
Understanding Dialysis Access Points and Their Locations
For individuals requiring hemodialysis, three primary types of access points are used. Each access type is created differently and placed in specific anatomical locations to facilitate the connection to the dialysis machine. The choice of access impacts how blood is drawn, filtered, and returned to the body.
Arteriovenous (AV) Fistula
An arteriovenous (AV) fistula is the preferred access for long-term hemodialysis because of its durability and lower complication rates. This access is created surgically by directly connecting an artery to a vein, typically in the arm. Common locations include the forearm, where the radial artery is joined to the cephalic vein, or the upper arm, connecting the brachial artery to the cephalic or basilic vein at the elbow crease. The surgical connection causes increased blood flow and pressure into the vein, making it enlarge and strengthen over several weeks to months, making it suitable for repeated needle insertions. Once matured, two needles are inserted into the fistula to draw and return blood.
Arteriovenous (AV) Graft
When a patient’s veins are not suitable for an AV fistula, an arteriovenous (AV) graft may be created. This access connects an artery to a vein using a synthetic tube to create the bridge. The graft is implanted under the skin, usually in the arm, connecting an artery to a vein. Common sites include the forearm or upper arm, though in some cases, it can be placed in the thigh. Needles are then inserted directly into the graft for dialysis treatment. Grafts can typically be used sooner than fistulas.
Central Venous Catheter (CVC)
A central venous catheter (CVC) is a flexible tube inserted into a large central vein. This access is used when immediate dialysis is needed or as a temporary measure until a permanent access can be created and matured. CVCs are commonly placed in veins in the neck, such as the internal jugular or subclavian veins. Sometimes, a CVC may be placed in the groin’s femoral vein. A portion of the catheter remains outside the body, allowing direct connection to the dialysis machine without needle insertions into the patient’s arm.
Factors Influencing Access Site Choice
Selecting the appropriate dialysis access type and location involves considering several medical and patient-specific factors. Providers evaluate these elements to ensure the best long-term outcome, balancing immediate needs with durability and safety.
Vein health is a primary consideration, as healthy, adequately sized veins are necessary for successful fistula creation. If veins are too small or damaged from previous procedures or medical conditions, a graft might be a more viable option. Overall health and medical history, including co-existing conditions, prior surgeries, or risk factors for complications, also play a significant role. These help determine which access is safest and most likely to function effectively.
The urgency of initiating dialysis influences the initial access choice. If immediate dialysis is required, a CVC is typically placed first as it can be used right away. Patient preference and lifestyle are also considered, such as discussing dominant arm placement to minimize impact on daily activities. Finally, the anticipated duration of dialysis guides whether a temporary or long-term access solution is appropriate.
Temporary Versus Long-Term Access
The distinction between temporary and long-term dialysis access is crucial, influencing the type and placement of access. This decision is based on immediate need and projected duration of treatment.
Temporary access, primarily central venous catheters (CVCs), is used for immediate dialysis needs, such as in emergency situations, or as a bridge while a more permanent access matures. These are inserted into large veins in the neck, chest, or sometimes the groin. While convenient for rapid use, CVCs are not intended for prolonged periods due to a higher risk of infection and other complications.
For sustained, ongoing dialysis treatment, long-term access types are preferred. Arteriovenous (AV) fistulas and AV grafts are designed for durability and repeated use. AV fistulas are typically created in the forearm or upper arm, while AV grafts are also commonly placed in the arms, or occasionally the thigh. These permanent accesses require time to mature or heal before they can be used for dialysis, but they offer a more robust and lower-risk solution for chronic kidney disease management.