Dialysis Pro · Vascular Access
Vascular Access
Selection, maturation, cannulation, surveillance, and thrombosis prevention for chronic hemodialysis access — AV fistula, AV graft, and tunnelled catheter.
⚠️ Clinical reference only. Reflects KDOQI 2019 / KDIGO 2024 / UpToDate guidance; individualise to patient anatomy, life-plan, and local protocol. Surveillance thresholds should be interpreted on trends, not single values. Developed by Dr. Abbas Deeb. Not affiliated with KDOQI, KDIGO, UpToDate, or any guideline body.
Access Types
Three principal forms · Upper extremity preferred
| Type | Construction | Key specs |
|---|---|---|
| AV fistula (AVF) | Native artery-to-vein anastomosis (end-to-side, vein-to-artery) | Radiocephalic (radial→cephalic) · Brachiocephalic (brachial→cephalic) · Brachiobasilic (brachial→basilic; needs superficialisation & transposition) |
| AV graft (AVG) | Synthetic conduit interposed between artery and vein | ePTFE, typically 6 mm (range 4–8) · straight/looped forearm or upper arm · early-cannulation grafts usable within 1 day |
| Tunnelled catheter (CVC) | Cuffed, tunnelled central venous device | Dual-lumen, 10–16 French · internal jugular preferred · Dacron cuff under skin |
Access is most commonly created in the upper extremity. Lower-extremity and upper-chest sites are used only when arm sites are exhausted; translumbar/transhepatic IVC catheters are last resort.
Complication profile: matured AVFs have the lowest complication rates and rarely become infected. AVGs have higher rates of venous-anastomotic stenosis, thrombosis, infection, and steal. CVCs carry the highest complication burden — infection, thrombosis, and central vein damage.
Source: UpToDate "Approach to the adult patient needing vascular access for chronic hemodialysis."
Selection & ESKD Life-Plan
Patient-centred — not "fistula first"
The KDOQI 2019 update replaced rigid "Fistula First" with the patient-centred ESKD Life-Plan (reviewed annually): preserve veins → individualise initial access → properly access/maintain/monitor → timely management with defined contingency and succession plans. Decisions use an interdisciplinary team (nurses, nephrologists, radiologists, vascular surgeons).
The historical AVF survival advantage is heavily confounded by selection bias — patients deemed fit for a fistula attempt have a survival advantage independent of whether they ever use the fistula. Patient factors likely explain at least two-thirds of the observed difference.
Appropriateness
| Access | Favoured when |
|---|---|
| AV fistula | Younger age, larger outflow vein & inflow artery diameter, normal/mild BMI, higher functional status. No absolute minimum diameter, but vessels <2 mm need careful evaluation. |
| AV graft | Expected dialysis duration <2 years and AVF not possible; older age, smaller veins. Early-use grafts expedite catheter removal. |
| Catheter (short-term) | AVF/AVG created but not ready; acute transplant rejection; PD complication needing temporary rest; living-donor transplant <90 days away; access complication needing temporary non-use. |
| Catheter (long-term) | Multiple failed accesses with no options; valid patient preference after informed discussion; limited life expectancy; no AV options (arterial/venous); special medical circumstances. |
Vein preservation (from CKD stage 4–5): avoid subclavian lines and PICCs (central stenosis risk); use internal jugular only for CVC; protect nondominant-arm veins and avoid phlebotomy there except dorsum of hand; protect the contralateral arm in patients with pacemakers or prior axillary dissection.
Source: UpToDate access overview; KDOQI 2019 Vascular Access Update.
Referral Timing
Two competing criteria — eGFR vs risk-equation
KDOQI 2019
eGFR 15–20
mL/min/1.73m² — esp. if declining
KDIGO 2024
KFRE ≥40%
2-year kidney failure risk
All predialysis patients expected to start HD within ~1 year, and any who started on a catheter, should be considered for AV access. The 2-year KFRE ≥40% criterion may discriminate kidney-failure-vs-death risk better than eGFR alone and reduce accesses created too early.
Factor in life expectancy: patients with longer expected dialysis survival gain more from an AVF. For limited life expectancy or imminent living-donor transplant, a tunnelled catheter may be the rational choice. Minimise catheter duration to avoid central vein stenosis that compromises future access.
Source: UpToDate access overview; KDOQI 2019; KDIGO 2024.
Failure & Patency
Reference figures for counselling & planning
| Metric | Figure |
|---|---|
| AVF primary failure | 23–60% (definition-dependent); ~33% in the Hemodialysis Fistula Maturation study |
| AVG primary failure | ~15–19% (about half the AVF rate) |
| 3-yr cumulative patency (incl. primary failure) | Radiocephalic 64% · Brachiocephalic 75% · Upper-arm 75% |
| CVC complications | 30% at 1 yr, 38% at 2 yr |
| CVC 1-yr bacteraemia | 9% (caused 72% of catheter-related hospitalisations) |
| AVF maturation interventions | ~35–38% need an intervention to facilitate maturation/manage complications |
When AVF primary failure is accounted for, cumulative patency of AVF and AVG is similar up to 3 years. AVFs once matured have the fewest long-term complications; counsel patients that additional interventions are commonly needed to achieve a functional fistula.
Source: UpToDate access overview (HFM study; Netherlands multicentre patency series).
Maturation & First Cannulation
Inspect at 4–6 weeks · Step up gauge & flow gradually
Examine the new AVF by an experienced clinician no later than 4–6 weeks after creation to judge clinical usability. It must be physiologically mature — adequate depth, length, and location to allow cannulation with minimal infiltration risk and deliver adequate flow.
Needle gauge ↔ maximal blood flow
| Needle | Max blood flow | Use |
|---|---|---|
| 17 gauge | ~250 mL/min | New fistulas — start here at 200 mL/min |
| 16 gauge | ~350 mL/min | ~300 mL/min needs 16 g |
| 15 gauge | ~450 mL/min | ~400 mL/min needs 15 g |
Ramp protocol: begin with a 17 g needle and blood flow limited to 200 mL/min; increase gauge (17→16→15) and flow (200→450 mL/min) gradually, roughly every 2 weeks. Each unit should have a defined protocol for stepping up needle size and flow.
Veins difficult to see or feel should be mapped with duplex ultrasound and marked with an indelible marker before cannulation. Only staff with technical mastery should cannulate a newly created fistula.
Source: UpToDate "Overview of hemodialysis AV fistula maintenance and thrombosis prevention."
Cannulation Technique
Rope-ladder preferred for thrice-weekly outpatient HD
| Technique | Method | Notes |
|---|---|---|
| Rope-ladder (standard) | Rotate cannulation sites each session; always sharp needles | Suggested for standard outpatient thrice-weekly HD (Grade 2B) |
| Buttonhole (constant-site) | Same site each time; ~10 cannulations (more in diabetes) to form an epithelialised track for dull/antistick needles | May improve survival but ↑ pain and ↑ bloodstream infection; reserve for short fistulas with limited cannulation length |
Buttonhole infection signal: one trial found localised infection 50 vs 22.4 per 1000 sessions (buttonhole vs standard); another found more needling-site abscesses requiring IV antibiotics. Not generally used in US outpatient units for this reason.
Procedure essentials
- Gloves + masks
- 2% chlorhexidine / 70% alcohol
- Bevel up ~15°
- Arterial antegrade/retrograde
- Venous antegrade
- Confirm with saline flush
Full barrier precautions (gowns, drapes) are generally not needed. Confirm needle placement with a saline flush — blood return alone is insufficient. Decannulation: remove at the insertion angle; apply pressure only after the needle is fully out; clot the needle track, not the fistula.
Infiltration: apply ice to reduce pain/size/bleeding; if infiltration occurs during initial cannulation release the tourniquet immediately; rest the fistula at least one treatment if possible, otherwise cannulate above the infiltration site. Don't re-attempt a failed cannulation site until healed.
Source: UpToDate "Overview of hemodialysis AV fistula maintenance and thrombosis prevention."
Monitoring & Surveillance
Nearly all clotted fistulas have an underlying stenosis
Almost all thrombosed mature AVFs have an underlying stenosis (one series: 100%). The aim is to catch treatable stenosis before thrombosis. Two distinct approaches: clinical monitoring (physical exam + routine data, no special equipment) and surveillance (specialised measurement of flow/pressure).
1
Clinical monitoring — weekly physical exam (KDOQI 2019)
Routine physical exam of every mature AVF each week. Look for extremity oedema, altered pulse/thrill/bruit, prolonged bleeding, collateral veins. Particularly suggestive of stenosis: failure to collapse on arm elevation (outflow) and lack of pulse augmentation (inflow) — pulse augmentation is more useful in newer, less rigid fistulas. Experienced-examiner physical exam reaches ~92% sensitivity / 86% specificity for outflow stenosis (operator-dependent).
- Cannulation difficulty
- Clot aspiration
- Can't reach target BFR
- Prolonged needle-site bleeding
2
Decreased Kt/V — the readily-available signal
An unexplained, persistent Kt/V drop >0.2 units on a fixed dialysis prescription warrants evaluation for access stenosis (cross-references the KPI / Adequacy tile).
3
Surveillance — access flow (Qa) is optimal for AVF
Intra-access flow monitoring is the best surveillance method for AVF (a low-pressure system). Qa <500 mL/min suggests underlying stenosis (threshold ~450–500 mL/min; one study: 465 mL/min, sensitivity 0.89). Duplex ultrasound flow screening + preemptive angioplasty reduced thrombosis (RR 0.45).
Static venous pressure is NOT useful for AVFs (low positive predictive value) — unlike for grafts. Don't rely on it for fistula surveillance.
Effectiveness caveat: evidence for complex surveillance programmes is weak (thrombosis is uncommon in AVFs; surveillance is unreimbursed in the US). General agreement favours simple weekly clinical monitoring. Nurse clinical-monitoring PPV for AVF stenosis is only ~39% — negative fistulograms are common.
Angiography referral (KDOQI 2019)
- Physical findings of stenosis
- Persistent Kt/V drop >0.2 units
- Access flow <400–500 mL/min
- Noninvasive evidence of abnormality
Rely on persistent findings with prospective trend analysis — not a single isolated value. Angiography should examine arterial inflow, the anastomosis, and outflow veins (multiple lesions in ≥⅓ of cases); angioplasty ± stenting can be done at the same time.
Source: UpToDate "Clinical monitoring and surveillance of the mature hemodialysis AV fistula"; KDOQI 2019.
High-Risk Fistula
Juxta-anastomotic stenosis is the dominant lesion
| Problem | Cause / feature | Management |
|---|---|---|
| Nonmaturing AVF | Most common = juxta-anastomotic stenosis (within 2 cm of anastomosis) | Ultrasound → balloon angioplasty; ligation of collateral veins may help redirect flow |
| Mature fistula stenosis | Also predominantly juxta-anastomotic | Angioplasty — but needing it is itself a failure-risk factor; recurrent stenosis = even higher failure |
| Aneurysm | Vein-wall thinning under pressure | Rarely causes failure unless very large |
| Pseudoaneurysm | From repeated same-site cannulation (not buttonhole) | May rupture or become infected — needs evaluation |
| Thrombosis without stenosis | Rare; cause unclear | Hypercoagulability is rarely the cause |
There are no proven pharmacologic therapies to improve maturation. Inadequate outward remodelling (suboptimal sustained dilation) is an important factor in nonmaturation; many fistulas mature despite some stenosis if outward remodelling is adequate. A secondary fistula is often possible after a failed AVF, treated analogously.
Source: UpToDate "Overview of hemodialysis AV fistula maintenance and thrombosis prevention."
Thromboprevention — What Not To Use
No drug reliably prevents AVF thrombosis
Unlike AV grafts, no pharmacologic therapy has proven benefit for AVF patency. For newly created AVFs, do not use these for the sole purpose of preventing thrombosis:
| Agent | Evidence | Recommendation |
|---|---|---|
| Aspirin | No improvement in patency (large trial: 45 vs 43% failure) | Suggest against (Grade 2B) |
| Other antiplatelets (clopidogrel, ticlopidine) | Mixed; may reduce early thrombosis but no reliable effect on usable-fistula rate | Suggest against (Grade 2C) |
| Fish oil (omega-3) | No benefit for AVF (47% failure each arm), unlike grafts | Suggest against (Grade 2B) |
| Systemic anticoagulation | Increased bleeding, no patency benefit | Recommend against (Grade 1B) |
| Cilostazol | One small nonrandomised maturation signal (88 vs 66%) | Investigational — not established |
Important caveat: antiplatelet therapy and fish oil may still be indicated for genuine cardiovascular benefit (BP lowering, secondary prevention), particularly in patients with coronary artery disease or risk equivalents — just not for the sole purpose of fistula thromboprevention.
Source: UpToDate "Overview of hemodialysis AV fistula maintenance and thrombosis prevention."
Dialysis Pro — Vascular Access · Sourced from UpToDate (access overview, AV fistula maintenance, and clinical monitoring/surveillance topics), KDOQI 2019 Vascular Access Update, and KDIGO 2024. Literature current through 2026.
Developed by Dr. Abbas Deeb. For clinical reference only. Surveillance thresholds and protocols must be individualised on trends and against local practice. Not affiliated with KDOQI, KDIGO, UpToDate, or any guideline body.
Developed by Dr. Abbas Deeb. For clinical reference only. Surveillance thresholds and protocols must be individualised on trends and against local practice. Not affiliated with KDOQI, KDIGO, UpToDate, or any guideline body.