For individuals facing kidney failure, hemodialysis becomes a necessary treatment, acting as a substitute for kidney function. Establishing reliable vascular access is essential for hemodialysis, as it allows blood to flow to and from the dialysis machine. Planning for appropriate vascular access well in advance is important for a smoother transition to treatment.
Choosing Your Dialysis Access
Hemodialysis requires consistent access to the bloodstream, typically through one of three primary types of vascular access: the arteriovenous (AV) fistula, the arteriovenous (AV) graft, and the central venous catheter (CVC). The AV fistula is widely considered the preferred long-term option for most patients needing hemodialysis. A surgeon creates a fistula by directly connecting an artery to a vein, typically in the arm. This connection increases blood flow into the vein, causing it to enlarge and strengthen over time, making it durable for repeated needle insertions during dialysis sessions. Fistulas generally have the lowest rates of infection and clotting, and they tend to last longer compared to other access types.
An AV graft involves surgically implanting a synthetic tube to connect an artery to a vein, serving as an artificial vessel for dialysis access. Grafts can be used sooner than fistulas but carry a higher risk of infection and clotting. A central venous catheter is a tube inserted into a large vein, usually in the neck or chest. While catheters can be used immediately, they are intended for temporary use due to the highest risk of infection and potential for blood clots.
The Right Time for a Fistula
The decision to create an arteriovenous fistula is made well before a patient begins hemodialysis. Healthcare providers recommend establishing this access months in advance to allow sufficient time for the fistula to develop and become ready for use. This proactive approach is particularly important as chronic kidney disease (CKD) progresses, especially during stages 4 or 5 when kidney function significantly declines.
Early creation allows for the necessary maturation period, during which the connected vein thickens and expands under increased blood flow, becoming robust enough to withstand the repeated needle punctures required for dialysis. This maturation process can take several weeks to many months, often ranging from two to six months. Planning ahead helps prevent the need for a temporary central venous catheter when dialysis becomes urgent.
A nephrologist, often in consultation with a vascular surgeon, determines the optimal timing for fistula placement. This assessment often includes vein mapping, a non-invasive test that images the veins and arteries to identify the most suitable vessels for the procedure.
After Fistula Creation
Following the surgical creation of an arteriovenous fistula, the initial focus is on recovery and the maturation phase. After the surgery, patients typically experience some swelling and discomfort at the site, which can be managed with pain medication.
The maturation process involves the newly connected vein adapting to increased blood flow by enlarging and thickening, preparing it for hemodialysis. During this period, patients are often advised to perform specific exercises, such as squeezing a soft ball, to encourage the vein’s development.
A maturing fistula can be identified by specific signs. Patients can often feel a “thrill,” which is a gentle vibration over the fistula, and hear a “bruit,” a whooshing sound, when listening with a stethoscope. These sensations indicate proper blood flow and a healthy developing access. The dialysis care team will regularly assess the fistula’s readiness to ensure it has adequately matured before it is used for treatment.
What If Your Fistula Isn’t Ready
There are instances where a patient might need to start dialysis urgently before their fistula has fully matured, or if the fistula fails to mature adequately after creation. In such scenarios, a temporary central venous catheter (CVC) is typically used to initiate dialysis treatment. While convenient for immediate access, CVCs are not recommended for long-term use due to several drawbacks.
Central venous catheters carry a higher risk of complications, including bloodstream infections and blood clots, compared to a mature fistula. They also often provide a slower blood flow rate, which can lead to less efficient dialysis treatments. Consequently, if a CVC is necessary, healthcare providers will often continue efforts to establish or mature a permanent access.
If a fistula does not mature or fails, other options are considered. This may involve creating a new fistula in a different location, if suitable vessels are available. Alternatively, an AV graft may be placed, which has a shorter maturation time than a fistula.