AV Graft Before a Permanent Catheter
If a native AVF cannot be created, an arteriovenous graft (AVG) is usually the next best option, preferred over a tunneled central venous catheter (CVC). AVFs are usually preferred because they have lower rates of infection and clotting, but AVGs are more likely to mature successfully, with failure rates of only 5%–20% compared to 20%–60% for AVFs. This makes AVGs a key part of a patient’s Access Succession Plan, especially when there are no suitable veins left or when issues like small vessels in the arm or damage from previous procedures are present.
One of the main benefits of AVGs is that they help reduce the need for central venous catheters (CVCs), which have the highest risks of serious infection and central vein narrowing. You can place a central catheter after using chances for an AV graft, but you cannot use an AV graft after a central catheter because catheters will cause central vein obstruction.
Fistulas are the gold standard, but grafts are an important bridge that offer safer and more effective dialysis than catheters. Catheters carry the highest risk to a patient’s life and long-term blood vessel health.
- The “Hierarchy of Harm”: Mortality & Infection
The main reason to choose a graft instead of a catheter is to improve patient survival.
- Risk:
Large-scale studies consistently show that patients using catheters have a 1.5- to 3-fold higher risk of death compared to those with grafts or fistulas. - Infection Rate:
Catheters are prone to infection. Since they exit the skin and remain outside the body, they give bacteria a direct path into the bloodstream.- Catheters:
The risk of bloodstream infection or sepsis is about 7 to 10 times higher with catheters than with AVFs. - Grafts:
Grafts can become infected since they are made of foreign material, but the risk is much lower than with catheters because grafts are placed under the skin and do not have a permanent opening.
- Catheters:
- Dialysis Adequacy (Cleaning the Blood)
Effective blood cleaning during dialysis requires a high blood flow rate, usually over 400 mL/min. Grafts are designed to handle high pressure and high flow, ensuring the patient gets a “full dose” of dialysis (high Kt/V).
- Catheters (Low/Variable Flow):
Catheters often experience problems with blood flow, such as blockages or clots at the tip. This can force nurses to slow the dialysis machine, leading to less effective treatment and a buildup of toxins.
- Preservation of “Future Options” (Central Veins)
This is an important factor for the patient’s long-term treatment plan.
- Catheter Damage:
Catheters are placed in large central veins. Over time, the plastic tube can cause inflammation and scarring, which may block the vein. If this happens, it is no longer possible to create a fistula or graft in that arm. - Graft Preservation:
Grafts are usually placed in the arm, which helps keep the central veins open for future access if needed.
- Maturation Speed (The “Early Cannulation” Advantage)
Sometimes, a catheter is used because a standard fistula takes months to mature. However, modern grafts can help fill this gap.
- Standard AVF: Needs 2–4 months to mature.
- Standard AVG: Can be used in 2–3 weeks.
- “Early Cannulation” AVG:
Newer graft materials (e.g., Acuseal) can be cannulated within 24 hours of surgery. This allows patients to bypass the catheter entirely, even in urgent starts.
Summary Comparison: Graft vs. Permanent Catheter
Feature | AV Graft (AVG) | Tunneled Catheter (CVC) |
|---|---|---|
Survival | Moderate Mortality Risk | Highest Mortality Risk |
Infection Risk | Moderate | Very High (Sepsis Risk) |
Blood Flow | Excellent (>400 mL/min) | Often Poor/Variable |
Anatomical Impact | Preserves Central Veins | Causes Central Vein Stenosis |
Usage | Long-term (Years) | Should Be Temporary |
Clinical Verdict
A catheter should only be used as a last resort, such as when a patient has no veins left for a graft, or as a short-term solution while a graft or fistula is healing. In nearly all other cases, a graft is safer and more effective.
