What are the guidelines for managing an Arteriovenous Fistula (AVF)?

Arteriovenous Fistula (AVF) Management Guidelines

The KDOQI 2019 guidelines prioritize routine physical examination monitoring over surveillance testing, with intervention reserved for stenosis >50% accompanied by clinical dysfunction, focusing on maintaining functional, complication-free access while preserving future access sites. 1

Routine Monitoring Strategy

Physical examination should be performed at every dialysis session using the "Look-Listen-Feel" approach rather than relying on expensive surveillance equipment. 1

Normal AVF Physical Examination Findings

• Look: Well-developed main venous outflow without irregular/dilated areas, aneurysm formations, or multiple accessory veins; adequate straight vein segments for two-needle rope-ladder cannulation 1
• Listen: Low-pitch continuous bruit present during both diastole and systole 1
• Feel: Thrill palpable at arterial anastomosis and throughout entire outflow vein that compresses easily 1

Abnormal Findings Requiring Further Evaluation

High-risk clinical indicators mandate immediate imaging and potential intervention: 1

• Ipsilateral extremity edema persisting beyond 2 weeks post-creation 1
• Abnormal thrill: Weak, discontinuous, or systolic-only component in stenosis region 1
• Abnormal bruit: High-pitched with only systolic component 1
• Pulse abnormalities: Water-hammer quality pulse at stenotic lesion site; weak or resistant pulse difficult to compress 1
• Failure to collapse when arm elevated (suggests outflow stenosis) or lack of pulse augmentation (suggests inflow stenosis) 1
• Dilated neck veins or surface collateral veins in arm/neck above the access 1

Dialysis-Related Warning Signs

Intervention is warranted when these occur: 1

• New difficulty with cannulation when previously successful 1
• Aspiration of clots during cannulation 1
• Inability to achieve target dialysis blood flow 1
• Prolonged bleeding beyond patient's usual pattern for 3 consecutive sessions 1
• Unexplained decrease in delivered Kt/V >0.2 units on constant prescription 1

Intervention Thresholds

Percutaneous transluminal angioplasty (PTA) or surgical revision is indicated when stenosis reaches >50% luminal diameter AND is associated with clinical/physiological abnormalities. 1, 2 This dual-criteria approach prevents unnecessary interventions on asymptomatic stenoses. 1

Specific Indications for Intervention

• Inadequate flow to support prescribed dialysis blood flow 1
• Reduction in access flow with abnormal physical findings 1
• Increased static pressures or access recirculation preventing adequate dialysis delivery 1
• Aneurysm formation with post-aneurysmal stenosis (avoid cannulating aneurysmal segment) 1

Patient evaluation should occur no later than 6 weeks after access placement to detect early dysfunction or maturation delays. 1

Management of Major Complications

Thrombosis

Thrombectomy should be attempted as early as possible after detection but can succeed even after several days. 1 Endovascular interventions are first-line treatment, with surgical thrombectomy reserved for endovascular failure. 2

Steal Syndrome (Limb Ischemia)

Immediate AVF closure is mandatory for monomelic ischemic neuropathy (acute neuropathy with global muscle pain, weakness, warm hand with palpable pulses starting within first hour post-creation). 1, 3

Emergent vascular surgery referral is required for: 1, 3

• Fingertip necrosis or gangrene (progression accelerates in final stages) 1, 3
• Severe symptomatic ischemia threatening limb viability 1, 3
• Tissue necrosis requiring immediate fistula outflow ligation 1, 3

Mild ischemia (coldness, pain during dialysis) often improves with time and requires only symptom-specific therapy. 2

Therapeutic options before dismantling: 1, 3

• Angioplasty of proximal arterial stenoses (except in advanced arterial calcification) 1, 3
• Flow reduction procedures, though traditional banding has poor success rates 1, 3

High-risk patients include elderly, diabetics, hypertensives with peripheral arterial disease history, and those with previous vascular surgery. 3

Infection

All AVF infections require 6 weeks of antibiotic therapy, analogous to subacute bacterial endocarditis. 1

Initial empiric therapy: Vancomycin plus aminoglycoside, then convert based on culture/sensitivities. 1

Cannulation must cease at infected sites and the arm should be rested. 1

Immediate surgery with tissue resection is required for infections at the AV anastomosis; if arterial segment resected, consider venous interposition graft or more proximal neo-anastomosis using degradable suture material. 1, 3

Persistent Extremity Edema

Imaging study (including dilute iodinated contrast) to evaluate central vein patency is required for edema persisting beyond 2 weeks. 1

PTA is preferred treatment for central vein stenosis. 1

Stent placement indicated for: 1

• Acute elastic recoil >50% stenosis after angioplasty 1
• Stenosis recurrence within 3 months 1

Aneurysm/Pseudoaneurysm

Urgent evaluation required for: 1, 4

• Poor eschar formation 1
• Spontaneous bleeding 1
• Rapid expansion 1
• Severe degenerative changes in graft material 1

Surgical repair indicated when: 1

• Limited cannulation sites due to large/multiple pseudoaneurysms 1
• Pseudoaneurysm threatens skin viability 1
• Symptomatic (pain, throbbing) 1
• Evidence of infection 1

Never cannulate through pseudoaneurysms, especially if enlarging. 1

Common Pitfalls to Avoid

Delaying evaluation of access dysfunction leads to thrombosis and access failure - act on clinical indicators immediately rather than waiting for complete access failure. 2, 4

Attempting cannulation through or near problematic sites exacerbates complications - establish temporary alternative access if necessary. 2, 4

Failing to recognize early ischemia signs delays intervention - regular assessment for ischemia is mandatory at every patient encounter. 1, 2

Underestimating significance of minor drainage or swelling can lead to inadequate management of serious complications like anastomotic leaks or infections. 4

Targeting thrombosis prevention in AVFs through aggressive intervention is counterproductive - the 2019 KDOQI update emphasizes this does not improve AVF survival and may harm access longevity. 1