Hemodialysis Vascular Access: AVF, AVG, and Tunneled Dialysis Catheter Clinical Guide

Hemodialysis vascular access represents a unique and specialized domain within vascular access practice. Unlike most IV therapy access — which uses central venous devices to deliver drugs or fluids — hemodialysis access must sustain high-volume extracorporeal blood flow (typically 300–500 mL/min) across three or more sessions per week, for years to decades. The vascular access itself becomes a critical long-term asset for the ESRD patient, and its preservation is a clinical and ethical priority.

Parent guide: Vascular Access Special Populations: Complete Reference

The Hemodialysis Access Hierarchy: Fistula First

KDOQI (Kidney Disease Outcomes Quality Initiative) guidelines and the Fistula First Breakthrough Initiative establish a priority hierarchy for hemodialysis access:

1. Arteriovenous Fistula (AVF) — Preferred 2. Arteriovenous Graft (AVG) — Second choice 3. Tunneled Dialysis Catheter (TDC) — Bridge or last resort only

This hierarchy is based on outcome data: AVFs have the longest functional survival, lowest infection rates, and lowest mortality associated with dialysis access. Tunneled catheters carry the highest mortality risk among ESRD patients — catheter-dependent dialysis is associated with substantially worse survival outcomes.

Clinical implication: Every ESRD patient on a tunneled catheter should have a plan and timeline for transition to AVF or AVG. Catheter dependence should never be considered a permanent solution unless no surgical options exist.

Arteriovenous Fistula (AVF)

What Is an AVF?

A surgical anastomosis between a peripheral artery and adjacent vein, creating a high-flow arteriovenous connection. Blood enters the vein at arterial pressure, causing the vein to dilate, thicken, and “mature” (develop the wall strength and flow capacity required for needle cannulation).

Common AVF configurations:

• Radiocephalic (Brescia-Cimino) fistula: Radial artery to cephalic vein at the wrist — the original and most durable AVF configuration; created first when feasible
• Brachiocephalic fistula: Brachial artery to cephalic vein at the antecubital fossa — larger, easier to mature than radiocephalic; used when wrist veins are inadequate
• Brachiobasilic fistula: Brachial artery to basilic vein — requires transposition of the basilic vein (a two-stage surgical procedure); created when cephalic vein is unusable

AVF Maturation: The “Rule of 6s”

An AVF requires maturation time before it can sustain repeated cannulation. The classic maturation target is the Rule of 6s:

• Blood flow ≥600 mL/min
• Vein diameter ≥6 mm
• Depth ≤6 mm beneath skin
• Length ≥6 cm of usable segment

Time to maturation: Most AVFs require 6–12 weeks after surgical creation before first use. Some AVFs (particularly radiocephalic in older or diabetic patients) require longer; some fail to mature at all (maturation failure rate 20–60% for radiocephalic in some populations).

Failure to mature: AVFs that do not achieve Rule of 6 criteria within 3–4 months should be evaluated by interventional radiology (fistulogram) to identify correctable causes (accessory veins causing outflow competition, anastomotic stenosis, central venous stenosis).

AVF Physical Assessment Before Cannulation

Before each dialysis session, assess the AVF:

1. Thrill: Palpate the fistula segment — a continuous vibratory sensation (thrill) indicates patent, high-flow access. A pulsatile (non-continuous) pulse without thrill suggests outflow stenosis — refer for evaluation.
2. Bruit: Auscultate with stethoscope — a continuous bruit is expected; a high-pitched or discontinuous bruit may indicate stenosis.
3. Site inspection: Look for signs of infection, aneurysm (excessively dilated segments), hematoma, skin breakdown over aneurysmal sites.
4. Blood flow: If measurable dialysis blood flow falls >25% from baseline, evaluate for stenosis.

AVF Cannulation Techniques

Rope-ladder technique: Cannulation sites rotate systematically along the entire length of the fistula segment, moving up and down like a ladder. Each session uses a new site. Allows the vessel wall to heal between uses. Standard recommended technique.

Buttonhole technique (constant-site cannulation): The same two sites are used for every session. With repeated needle insertion at the same site at the same angle and depth, a fibrous “tunnel” develops through subcutaneous tissue into the vessel — subsequent needle insertion follows this established track. Advantages: less pain after track establishment, less skill required for each cannulation. Disadvantages: buttonhole sites are a significant infection risk (skin colonization in the fibrous tract → bacteremia); requires scrupulous skin antisepsis; MRSA bacteremia has been associated with buttonhole technique. Not recommended as first-line at most centers due to infection risk.

Cannulation needle gauge: Standard dialysis needles are 15G or 16G (AV fistula needles are large-bore by IV standards — required to achieve 300–500 mL/min blood flow).

Arteriovenous Graft (AVG)

What Is an AVG?

A synthetic graft (expanded polytetrafluoroethylene, ePTFE) or biological conduit surgically interposed between artery and vein, creating a bridge for dialysis cannulation. The graft surface can be cannulated directly.

Common AVG configurations:

• Forearm loop graft (radial artery to antecubital vein)
• Upper arm straight graft (brachial artery to axillary vein)
• Thigh graft (superficial femoral artery to femoral vein) — used when upper extremity exhausted

AVG vs AVF: Key Differences

AVG Cannulation

Similar to AVF cannulation technique (rope-ladder vs buttonhole). The graft can be cannulated as soon as it is patent (typically 2–3 weeks post-surgery, allowing edema resolution and tissue incorporation). No maturation period is required — the graft material is immediately cannulable.

Cannulation of a graft that is too edematous or too fresh (within the first 2 weeks) risks hematoma formation and graft failure.

Tunneled Dialysis Catheter (TDC)

Indications for TDC

TDC is a central venous catheter designed specifically for high-flow hemodialysis. Indications:

• Bridge access: While awaiting AVF maturation or surgical AVF/AVG creation in a patient newly starting dialysis
• Failed AVF/AVG: When all surgical access options are exhausted
• Acute renal failure: Short-term dialysis when recovery is anticipated
• Patient preference or inability to undergo surgery: Rare; must be carefully documented

TDC Anatomy and Features

• Size: Typically 12–14 Fr dual-lumen catheter (compared to 7–8 Fr for most CVCs); large bore required for dialysis blood flow
• Tunneling: TDC has a subcutaneous tunnel from insertion site to exit site, with a Dacron cuff at the midpoint — same as Hickman-type tunneled CVCs; cuff provides infection barrier and anchoring after tissue ingrowth (4–6 weeks)
• Tip location: IVC-RA junction (for femoral insertion) or RA/SVC-RA junction (for IJ or subclavian insertion). Right atrial position is required for adequate blood flow
• Dual-lumen configuration: Arterial port (draws blood out to dialyzer) and venous port (returns blood from dialyzer) — arterial port tip typically 2 cm proximal to venous port

TDC Insertion Sites

Right internal jugular (preferred): Provides the most direct path to the right atrium; lowest rate of central venous stenosis; lowest catheter dysfunction rate.

Left internal jugular: Longer path, requires more catheter length; higher catheter dysfunction rate.

Subclavian: Higher rate of central venous stenosis — avoid in ESRD patients (central venous stenosis at the subclavian → SVC junction can be limb-threatening for a future ipsilateral AVF).

Femoral: Reserved for when all jugular/subclavian options are exhausted; highest infection rate; patient cannot ambulate effectively; used as bridge only.

TDC Complications and CLABSI Risk

TDC carries the highest CLABSI rate of all hemodialysis access options:

• Rate: 2–7 per 1,000 catheter-days (compared to 0.5–1.0/1,000 for tunneled non-dialysis CVCs)
• ESRD patients have baseline immune dysfunction (uremia impairs neutrophil function)
• Dialysis sessions involve mandatory hub manipulation 3× per week (connecting/disconnecting dialysis tubing)
• Heparin locks in TDC create an ideal environment for biofilm formation

Organisms: S. aureus (including MRSA) and Staphylococcus epidermidis are the most common TDC CLABSI pathogens. Gram-negative bacteremia from TDC indicates possible hematogenous seeding from another source.

Prevention:

• Antimicrobial lock therapy (ALT): taurolidine-citrate or gentamicin-citrate locks in TDC are the highest-evidence intervention for catheter-related bacteremia prevention in dialysis patients (KDOQI 2019; Cochrane meta-analysis 2014)
• Mupirocin nasal ointment: Applies to dialysis catheters — nasal S. aureus carriage is a major source of TDC CLABSI; mupirocin nasal ointment 3× weekly reduces S. aureus CLABSI in dialysis patients
• Exit site antisepsis: Povidone-iodine or CHG applied to exit site at each dialysis session
• Passive disinfection caps: Alcohol-impregnated caps on arterial and venous ports between sessions

TDC Lock Solutions

Standard TDC locking between dialysis sessions uses heparin (concentration per institutional protocol — typically 1,000 units/mL or 5,000 units/mL, filling only the catheter dead space — DO NOT flush through with full-volume heparin, as systemic heparinization will occur).

Alternatives when heparin is contraindicated (HIT):

• Citrate 4% (anticoagulant, antimicrobial — evidence-supported alternative to heparin in dialysis catheters)
• Normal saline (minimal anti-thrombotic effect; not recommended for TDC as sole lock)

Vessel Preservation in CKD and ESRD: The Critical Clinical Imperative

The most clinically important contribution a vascular access clinician makes to a CKD/ESRD patient’s long-term outcomes may be preserving the forearm and antecubital veins for future AVF creation.

What Not to Do in CKD/ESRD Patients

Do NOT place PICCs or midline catheters in the following veins in a CKD/ESRD patient without explicit nephrology consultation:

• Cephalic vein (forearm or upper arm)
• Basilic vein
• Brachial vein

These are the primary AVF creation veins. Damage from PICC insertion, phlebitis, or thrombosis can permanently eliminate a potential AVF site.

Do NOT place subclavian CVCs in ESRD patients — subclavian venous stenosis eliminates the ability to create an ipsilateral AVF.

Do NOT draw blood or place PIVs in the antecubital fossa or cephalic vein of a CKD patient if an AVF is planned in that arm.

Safe Vascular Access Strategies for CKD Patients

• Use the non-dominant arm for all non-dialysis IV access whenever possible
• Use hand veins (dorsal) rather than forearm/antecubital veins
• For central access: use right internal jugular CVC or PICC — NOT subclavian
• Document CKD status in clinical records and alert team to vessel preservation requirements
• Consult nephrology or vascular access team before placing any central venous device in a CKD patient (GFR <30 mL/min)

Transition from TDC to AVF/AVG

When an AVF or AVG matures, the transition from TDC to native/prosthetic access is a critical clinical event:

1. Assessment of access maturation: Confirm Rule of 6s criteria are met (for AVF); confirm graft is mature and edema has resolved (for AVG)
2. Trial cannulation: First attempt at needle cannulation — should be performed by an experienced dialysis nurse; document outcome
3. Catheter removal: Once AVF/AVG is successfully supporting full dialysis sessions, remove TDC as soon as practical. Every day a TDC remains in place in a patient with functional AVF/AVG represents unnecessary CLABSI risk.
4. Catheter removal procedure: Tunneled catheters require Dacron cuff removal — a bedside or minor procedural suite procedure involving blunt dissection over the cuff site under local anesthesia

Related Resources

Related guides:

• Hemodialysis Vascular Access Overview
• CLABSI Prevention: Maintenance Bundle
• Antimicrobial Catheters and Dressings
• Vascular Access Special Populations

References

1. KDOQI Clinical Practice Guidelines and Recommendations. (2006). Hemodialysis Adequacy, 2006. Am J Kidney Dis, 48(Suppl 1):S1–S322.
2. Lok CE, et al. (2020). KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis, 75(4 Suppl 2):S1–S164.
3. Murea M, et al. (2019). Hemodialysis vascular access in the elderly. Semin Dial, 32(1):29–38.
4. Biuk-Aghai E, et al. (2014). Taurolidine-citrate catheter locks for the prevention of catheter-related bacteremia in hemodialysis patients: Cochrane review. Cochrane Database Syst Rev.
5. Gorski LA, et al. (2021). INS Infusion Therapy Standards of Practice. J Infus Nurs, 44(Suppl 1).