What are the medical clearance requirements for patients undergoing AV (Arteriovenous) fistula creation?

Medical Clearance Requirements for AV Fistula Creation

Patients with chronic kidney disease should be referred for AV fistula creation when their creatinine clearance is 25 mL/min, serum creatinine level is 4 mg/dL, or within 1 year of anticipated need for dialysis to ensure adequate time for fistula maturation and potential revision if needed. 1

Preoperative Vascular Assessment

• Duplex ultrasound is the preferred method for preoperative vascular mapping and should be performed in all patients before placement of an AV fistula 1
• Arterial evaluation should include:
  • Pulse examination
  • Differential blood pressure measurement
  • Assessment of palmar arch patency
  • Arterial diameter measurement (minimum 2.0 mm diameter required) 1
  • Evaluation for arterial calcification 1
• Venous evaluation should include:
  • Luminal diameter measurement (minimum 2.5 mm diameter required)
  • Confirmation of continuity with proximal central veins
  • Absence of obstruction 1
• Central veins should be assessed by duplex ultrasound, venography, or magnetic resonance angiography to rule out central venous stenosis 1

Patient Selection Criteria

• Successful AV fistula creation is associated with:
  • Target artery diameter ≥2.0 mm 2, 3
  • Target vein diameter ≥2.5 mm 2, 3
  • Absence of central venous stenosis 1
• The "Rule of 6s" can help predict fistula maturation:
  • Blood flow >600 mL/min
  • Vein diameter >6 mm
  • Vein depth <6 mm 3
• Of these criteria, flow volume and vein depth are the strongest predictors of successful maturation 3

Vein Preservation Strategies

• Protect arm veins in patients with creatinine >3 mg/dL or conditions likely to lead to ESRD 1, 4
• Avoid venipuncture and IV placement in potential fistula sites 1, 4
• When venipuncture is necessary, use dorsum of the hand rather than arm veins 4
• Strictly avoid subclavian vein catheterization due to high risk of central venous stenosis 1, 4
• Internal jugular vein is the preferred site for temporary central venous access 4
• Consider Medic Alert bracelet to inform hospital staff to avoid IV cannulation of essential veins 1

Timing Considerations

• AV fistula should be created at least 1 month, and ideally 3-4 months, before anticipated need for dialysis 1
• For patients not suitable for AV fistula, AV grafts should be placed 3-6 weeks before anticipated need for hemodialysis 1
• Hemodialysis catheters should not be inserted until hemodialysis is actually needed 1
• Early referral allows time for:
  • Fistula maturation (1-4 months)
  • Potential revision procedures if needed
  • Avoiding temporary catheter placement 1

Maturation Assessment

• A primary AV fistula is considered mature when:
  • Vein diameter is sufficient for successful cannulation
  • At least 1 month has passed since creation (preferably 3-4 months) 1
• Fistula hand-arm exercises (squeezing a rubber ball) can increase blood flow and speed maturation 1
• If a new fistula is infiltrated (hematoma with induration and edema), it should be rested until swelling resolves 1

Common Pitfalls to Avoid

• Premature cannulation of a fistula may result in infiltration, hematoma, and permanent loss of the fistula 1
• Subclavian vein catheterization can cause central venous stenosis that precludes use of the entire ipsilateral arm for vascular access 1, 4
• Peripherally inserted central catheters (PICCs) should be avoided in patients with advanced kidney disease due to similar risks of venous damage 4
• Failure to identify accessory veins or venous side branches may lead to poor maturation 1
• Higher body mass index is associated with failure to mature, particularly due to increased vein depth 3

By following these medical clearance requirements, the success rate of AV fistula creation and maturation can be significantly improved, reducing the need for temporary catheter placement and associated complications.