What is the preferred vascular access for chronic hemodialysis and how should one choose between an autogenous arteriovenous fistula (AVF), a prosthetic arteriovenous graft (AVG), and a tunneled central venous catheter (CVC)?

Vascular Access in Hemodialysis

Primary Recommendation

An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis in most patients due to significantly lower infection risk, fewer complications, and superior long-term outcomes compared to arteriovenous grafts (AVG) or central venous catheters (CVC). 1, 2

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Hierarchical Approach to Access Selection

First-Line: Arteriovenous Fistula (AVF)

AVF should be the default choice when clinical circumstances permit, specifically when:

• Adequate vessel anatomy exists (suitable arteries and veins for anastomosis) 1
• Sufficient time for maturation (3-4 months before anticipated dialysis start) 2
• Life expectancy exceeds 1 year 3
• Patient circumstances are favorable (considering comorbidities, vessel characteristics, and functional status) 1

Key advantages of AVF:

• Lowest infection rate: 1-4% over entire use-life, representing a 7-fold lower bacteremia risk compared to catheters 2
• Superior patency: Target thrombosis rate <0.25 episodes per patient-year 2
• Lowest mortality: Associated with significantly lower death rates compared to CVC (1.5 to 5-fold reduction depending on patient characteristics) 3
• Fewest complications: 3-7 times fewer complication events than prosthetic grafts 2

Preferred anatomic sequence for AVF placement:

1. Radial-cephalic (wrist) fistula
2. Brachial-cephalic (elbow) fistula
3. Alternative autogenous options (e.g., brachial vein transposition) 1, 2

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Second-Line: Arteriovenous Graft (AVG)

AVG should be selected when AVF is not feasible due to:

• Inadequate superficial veins (exhausted, obliterated, or unsuitable caliber) 4, 5
• Urgent dialysis need with insufficient time for AVF maturation (though tunneled CVC bridge is preferred in this scenario) 2
• Multiple prior AVF failures 1

Key characteristics of AVG:

• Intermediate infection rate: 11-20% over use-life, approximately 3-5 times higher than AVF 2
• Acceptable patency: Target thrombosis rate <0.5 episodes per patient-year (double the AVF rate) 2
• Higher intervention burden: Requires approximately 3.3 procedures per year to maintain function versus 1.8 for AVF 6
• Functional patency comparable to AVF at 1 year (85% vs 83% for upper arm AVF), but requires more maintenance 6

Preferred anatomic sequence for AVG placement:

1. Forearm loop graft
2. Upper arm straight graft
3. Upper arm loop graft 4

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Third-Line: Tunneled Central Venous Catheter (CVC)

Tunneled CVC should be reserved for specific clinical circumstances only, as it carries the highest infection and mortality risk. 1, 3

Short-Term Indications (Acceptable CVC Use):

• AVF or AVG created but not yet mature and dialysis is required 1
• Acute transplant rejection or complications requiring temporary dialysis 1
• Pending living donor transplant with confirmed operation date <90 days 1
• AVF/AVG complication (major infiltration, cellulitis) requiring temporary non-use 1

Long-Term Indications (Acceptable CVC Use):

• Multiple prior failed AV accesses with no remaining anatomic options 1
• Anatomic impossibility: Severe arterial occlusive disease, uncorrectable central venous stenosis, or prohibitively small vessels 1
• Limited life expectancy where AVF maturation time exceeds expected survival 1, 3
• Valid patient preference after thorough informed discussion of risks, where AV access would severely limit quality of life or life goals 1

Key risks of CVC:

• High infection rate: 50% removal due to infection at 1 year; bacteremia rate 1.6 per 1,000 catheter-days for tunneled CVC 2
• Increased mortality: 1.5 to 5-fold higher death rate compared to AVF 3
• Higher hospitalization rates compared to AVF or AVG 5

Preferred anatomic sequence for tunneled CVC placement:

1. Right internal jugular vein
2. Left internal jugular vein
3. External jugular vein
4. Femoral vein
5. Subclavian vein (avoid if possible—see critical pitfall below) 4

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Critical Decision Algorithm

When evaluating a patient for hemodialysis access:

1. Assess vessel anatomy (physical exam ± ultrasound): Can an AVF be created?

   • Yes → Proceed with AVF (wrist first, then elbow)
   • No → Proceed to step 2

2. Determine time to dialysis initiation:

   • >3-4 months available → Create AVF and allow maturation
   • <3-4 months but >2 weeks → Create AVF and bridge with tunneled CVC
   • Immediate dialysis required → Place tunneled CVC, plan AVF for future conversion

3. If AVF not possible, assess for AVG:

   • Adequate arterial inflow and venous outflow → Create AVG
   • No adequate vessels → Proceed to step 4

4. If neither AVF nor AVG possible:

   • Evaluate for long-term CVC indications (see above)
   • Convert to AVF/AVG as soon as anatomically feasible to reduce infection and mortality risk 1

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Critical Pitfalls to Avoid

Subclavian Vein Catheter Placement

Never use the subclavian vein for CVC placement unless absolutely no alternative exists. Subclavian catheterization causes central venous stenosis in 42% of patients and permanently compromises future AVF creation in the ipsilateral arm. 3

Delayed Access Planning

Refer patients to nephrology early (when eGFR <20-30 mL/min) to enable AVF creation 3-4 months before anticipated dialysis start. Late referral results in up to 73% of patients requiring emergency catheter placement, exposing them to unnecessary infection and mortality risk. 2, 3

Prolonged CVC Dependence

Most incident HD patients starting with a CVC should convert to AVF or AVG as soon as possible to reduce infection, bacteremia, and hospitalization risk. 1 The goal is <10% of chronic maintenance HD patients remaining on permanent catheter. 2

Non-Tunneled Catheter Duration

Non-tunneled catheters should only be used for <2 weeks. Infection incidence is <8% at 2 weeks but increases exponentially with time (2.7 per 1,000 catheter-days vs 1.6 for tunneled). 1, 2

Ignoring Patient-Specific Factors

The choice between AVF and AVG should incorporate clinical judgment considering vessel characteristics, patient comorbidities, and life expectancy. 1 While AVF is preferred when circumstances are favorable, AVG may be more appropriate in patients with limited life expectancy or poor vessel quality where AVF maturation is unlikely. 6

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Special Considerations

Age and Sex Differences

Mortality benefit of AVF over CVC is most pronounced in patients <80 years old. 3 The hazard ratio for CVC versus AVF is stronger in men (2.0) than women (1.0), suggesting sex-specific risk stratification may be warranted. 3

Conversion Timeline

Early conversion from CVC to AVF/AVG within the first 6 months is recommended to minimize mortality exposure, though evidence is insufficient to mandate conversion within the first year solely for mortality reduction. 1, 3

Monitoring and Maintenance

Establish a multidisciplinary vascular access team (nephrologist, vascular surgeon, interventional radiologist, dialysis staff) to provide surveillance and early intervention for access dysfunction. 5 Target AVF thrombosis rates should be ≤0.25 episodes per patient-year and AVG ≤0.5 episodes per patient-year. 2