An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein, typically in the arm. This specialized access point is designed for individuals undergoing hemodialysis, providing a long-term, reliable site for the high blood flow rates necessary for effective treatment. Regularly checking the fistula’s function is important to ensure its continued viability and detect potential problems early.
Signs of a Well-Functioning Fistula
A healthy AV fistula exhibits distinct physical signs that indicate proper blood flow. One primary indicator is the “thrill,” a gentle, pulsating vibration felt over the fistula. This sensation is often described as feeling like a cat purring or a gentle buzzing under the skin. To check for the thrill, lightly place your fingertips over the skin where the fistula is located. A consistent and easily palpable thrill signifies that blood is flowing smoothly.
Another significant sign of a working fistula is the “bruit,” a whooshing or swishing sound produced by the rapid flow of blood. While sometimes strong enough to be felt as a vibration, the bruit is typically heard using a stethoscope placed gently over the fistula. A continuous, low-pitched sound indicates good blood flow. Familiarity with the normal feel of your thrill and sound of your bruit is key, as these are personalized indicators of your fistula’s health.
A well-functioning AV fistula should also appear healthy upon visual and tactile inspection. The skin over the fistula should be warm to the touch, reflecting adequate blood circulation. It should not show signs of discoloration, such as unusual redness or purplish hues. There should be no significant swelling around the fistula site or in the arm.
Warning Signs of Fistula Problems
The complete absence of a thrill or bruit is a serious warning sign, suggesting that blood flow through the fistula may have stopped or become severely compromised. Any noticeable change in the quality of the thrill, such as it becoming weaker, intermittent, or feeling different than usual, also warrants attention. Similarly, an inconsistent or changed pitch in the bruit can signal issues like narrowing of the vessel (stenosis).
Localized swelling, new or worsening pain, or tenderness over the fistula are concerning symptoms. Discoloration, such as unusual redness, warmth, or a blue/purple tint, may suggest inflammation or infection. If the arm or hand containing the fistula feels unusually cool or cold, or experiences new numbness or tingling in the fingers, this could be a sign of “steal syndrome,” where the fistula diverts too much blood away from the hand.
If bleeding from the access site continues for an unusually long time (e.g., more than 20 minutes) after dialysis, it might indicate a problem with blood flow or vessel narrowing. Signs of infection, such as fever, pus, or spreading redness and warmth at the site, require immediate attention.
When to Contact Your Healthcare Provider
Recognizing and acting on warning signs is important for maintaining the long-term health of your AV fistula. If you observe the absence or a significant change in your fistula’s thrill or bruit, contact your healthcare provider immediately. Swift action can often prevent minor issues from escalating into more serious complications.
Urgent reasons to contact your healthcare team include sudden swelling in the fistula arm, severe or new pain at the access site, or any signs suggesting infection like fever or pus. Prolonged bleeding after dialysis sessions also indicates a potential problem. It is important to avoid attempting to resolve these issues on your own. Prompt intervention by a nephrologist, dialysis center staff, or vascular specialist can often save the fistula and ensure continued access for dialysis treatments.