When kidneys fail, leading to end-stage renal disease, hemodialysis becomes a life-sustaining treatment. This process circulates a patient’s blood through an artificial kidney machine for cleansing, requiring a reliable access point.
What is an Arteriovenous (AV) Fistula?
An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein, typically in the arm. This direct connection allows high-pressure arterial blood to flow directly into a vein, providing a durable access point for hemodialysis. AV fistulas are the preferred method for dialysis access, offering lower infection and clotting rates and a longer functional lifespan. The increased blood flow and pressure from the artery cause the connected vein to enlarge and thicken, a process called arterialization, which makes it strong enough for dialysis.
The Surgical Creation Process
Creating an AV fistula involves a surgical procedure that is often performed as an outpatient treatment, typically under local or regional anesthesia. During the surgery, a small incision is made, usually in the arm, to access a suitable artery and vein. A surgeon then directly connects these two vessels.
Common locations for fistula creation include the wrist (radiocephalic fistula) or the elbow (brachiocephalic fistula). After the connection is established, a maturation period begins, during which the vein enlarges and its walls thicken in response to the increased blood flow and pressure. This maturation can take several weeks to months, and the fistula cannot be used for dialysis until it has adequately developed.
How an AV Fistula Functions for Dialysis
The direct surgical connection between an artery and a vein creates a pathway where high-pressure arterial blood flows directly into the lower-pressure venous system. This increased pressure and volume of blood flow into the vein stimulates it to undergo a process known as arterialization. Over time, the vein dilates and its walls become thicker, transforming it into a robust vessel capable of handling dialysis.
During a hemodialysis session, two specialized needles are inserted into the matured AV fistula. One needle acts as the arterial access, drawing blood from the patient’s body to the dialysis machine for filtration. The other needle serves as the venous return, sending the cleansed blood back into the patient’s bloodstream. The high volume of blood flow through the enlarged fistula is essential for efficient hemodialysis.
Daily Care and Monitoring
Daily care and monitoring are important for maintaining the long-term function of an AV fistula. Patients should keep the fistula site clean, washing it gently with soap and water daily to reduce the risk of infection. It is also important to protect the fistula from injury; this includes avoiding tight clothing, jewelry, or blood pressure cuffs on the arm with the fistula. Heavy lifting or sleeping on the fistula arm should also be avoided.
Patients are encouraged to regularly check their fistula for a “thrill,” a buzzing or vibrating sensation, and a “bruit,” a whooshing sound. These sensations indicate proper blood flow and a functioning fistula. Any changes, such as the absence of a thrill or bruit, unusual pain, swelling, redness, warmth, or numbness and coldness in the hand (which could indicate a condition like steal syndrome), warrant immediate medical attention.