🩸 Vascular Access for Hemodialysis AVF · AVG · CVC
The "lifeline" for hemodialysis patients — selecting, maintaining, and monitoring vascular access for optimal outcomes
Reliable vascular access is essential for adequate hemodialysis. The "Fistula First" initiative promotes native arteriovenous fistula (AVF) as the preferred access due to better longevity and fewer complications. However, access choice must be individualized based on patient vasculature, comorbidities, and expected dialysis vintage.
🔗 Arteriovenous Fistula (AVF)
Gold standard — native vein anastomosed directly to artery.
- Best longevity (years to decades)
- Lowest infection rate (<1% per year)
- Lowest thrombosis rate
- Requires 2–6 months to mature
- Requires adequate vessels (cephalic vein, radial/brachial artery)
✅ Fistula First Breakthrough Initiative (FFBI): AVF should be the first choice for incident patients.
🧵 Arteriovenous Graft (AVG)
Synthetic bridge (PTFE or polyurethane) connecting artery and vein.
- Shorter maturation (2–4 weeks)
- Higher infection rate (10–20% per year)
- Higher thrombosis rate than AVF
- Limited lifespan (2–5 years)
- Preferred when native veins are inadequate
🩹 Indication: Failed AVF or unsuitable vasculature — still superior to catheters.
📌 Central Venous Catheter (CVC)
Tunneled cuffed catheter placed in jugular or subclavian vein.
- Immediate use (no maturation)
- Highest infection rate (≥1.5–2 episodes per year)
- Highest thrombosis and stenosis risk
- Associated with increased mortality
- Should be a bridge, not permanent access
⚠️ Last resort: CVCs double the risk of bacteremia and death compared to AVF.
⚠️ Access Complications
Stenosis (most common):
- Neointimal hyperplasia at anastomosis or venous outflow
- Leads to ↓ access flow, ↑ recirculation, ↓ Kt/V
- Treatment: Angioplasty (±stent)
Thrombosis:
- Clotting of the access — sudden loss of thrill/bruit
- Treatment: Thrombolysis, thrombectomy, or surgical revision
Infection:
- AVF/AVG: cellulitis, abscess, septic emboli
- CVC: exit-site infection, tunnel infection, bacteremia (S. aureus, coagulase-negative staph)
🔧 Other Complications & Management
Steal syndrome (distal ischemia):
- Hand pain, coldness, paresthesia, ulceration
- Severe cases require surgical banding or ligation
High-output heart failure:
- Excessive flow → high cardiac output → CHF exacerbation
Aneurysm / pseudoaneurysm:
- From repeated cannulation → risk of rupture
📈 Surveillance: Monthly access flow monitoring, quarterly ultrasound for stenosis.
📊 Access Monitoring & Surveillance Techniques
🩺 Physical Examination (Daily):
- Palpate thrill (normal: continuous, soft thrill)
- Auscultate bruit (normal: low-pitched, continuous)
- Check for swelling, redness, pulsatility
📉 Access Flow Measurement (Monthly):
- Ultrasound dilution (Transonic HD01, HD02)
- Critical threshold: < 600 mL/min (AVF), < 800 mL/min (AVG)
- Trend evaluation: ↓ >25% over 4 months
🔄 Recirculation Measurement:
- Two-needle urea-based method (stop-flow)
- Ionic dialysance (online measurement)
- Normal: <5–10%; Elevated: >10–15% suggests stenosis
📈 Kt/V Adequacy:
- Unexplained drop in Kt/V despite unchanged prescription
- May indicate access dysfunction or recirculation
⚠️ Indications for referral to interventional nephrology / vascular surgery:
- ↓ Access flow below threshold
- Persistent elevated recirculation (>15%)
- Abnormal physical exam (weak thrill, pulsatile, edema)
- Unexplained Kt/V decline
- Difficulty cannulating
- Prolonged bleeding after needle withdrawal
🔍 AVF vs AVG vs CVC: Head-to-Head Comparison
| Parameter | AVF (Native) | AVG (Synthetic) | CVC (Tunneled) |
|---|---|---|---|
| Maturation time | 2–6 months | 2–4 weeks | Immediate |
| Infection rate (per year) | <1% | 10–20% | ≥150–200% (1.5–2 episodes) |
| Thrombosis rate | 0.1–0.2 episodes/year | 0.5–1.0 episodes/year | High (up to 50% at 1 year) |
| Primary patency (1 year) | 60–80% | 50–70% | 40–60% |
| Longevity | Years to decades | 2–5 years | Months |
| Mortality risk (vs AVF) | Reference | Risk ratio ~1.3–1.5 | Risk ratio ~2.0–2.5 |
| Preferred for long-term HD | ✅ First choice | ✅ Second choice | ❌ Last resort (bridge only) |
Data sources: DOPPS, USRDS, NKF-KDOQI guidelines
🧠 KDOQI Clinical Practice Recommendations (2020 Update):
- "Fistula First, Catheter Last" — AVF preferred for incident patients with life expectancy >2 years
- End-stage renal disease (ESRD) Life-Plan: Individualized access strategy based on patient's "vascular access journey"
- Timely creation: AVF placed at eGFR 15–20 ml/min or 6–12 months before anticipated HD start
- Surveillance: Routine access flow monitoring recommended for AVG and selected AVF
- Catheter reduction: Target CVC rate <10% of prevalent patients