Vascular Access for Hemodialysis

Dialysis Access - Kidney's Best Friend

• Lifeline for End-Stage Renal Disease (ESRD) patients needing Hemodialysis (HD).
• Provides reliable, long-term vascular access for efficient blood purification.
• Indications for HD initiation & access planning:
  • GFR < 15 mL/min/1.73m² (CKD Stage 5)
  • Symptomatic uremia (e.g., pericarditis, encephalopathy)
  • Refractory hyperkalemia, fluid overload, or acidosis

⭐ Plan for access creation when GFR < 20-25 mL/min or 6-12 months before anticipated HD start to allow maturation.

Access Types - Vein, Graft, or Catheter?

• KDOQI Preference: AVF > AVG > CVC (Fistula First)
• 1. Arteriovenous Fistula (AVF) - Gold Standard
  • Anastomosis: Native artery to vein (e.g., Radiocephalic).
  • Pros: Best patency, ↓complications (infection, thrombosis).
  • Cons: Maturation 6-12 weeks (or longer); primary failure common.

  ⭐ Rule of 6s (mature AVF): Flow >600mL/min, Diameter >6mm, Depth <6mm, Length >6cm.

• 2. Arteriovenous Graft (AVG)
  • Material: Synthetic tube (PTFE) bridging artery & vein.
  • Pros: Usable 2-4 weeks; for poor veins.
  • Cons: ↑Stenosis (venous anastomosis), thrombosis, infection vs AVF.
• 3. Central Venous Catheter (CVC)
  • Types: Tunneled (long-term), Non-tunneled (short-term/urgent).
  • Pros: Immediate use; bridge access.
  • Cons: Highest risk: infection (BSI), central vein stenosis.
  • Site: RIJV preferred; avoid subclavian (stenosis).

Pre-Op Planning - Measure Twice, Cut Once

• Clinical Evaluation:
  • History: Prior access, central lines, pacemakers, IVDU, dominant arm.
  • Exam: Bilateral BP, pulses, Allen's Test (crucial for radiocephalic AVF), vein inspection & palpation (with tourniquet).
• Duplex Ultrasound (Vessel Mapping): Essential for optimal site selection.
  • Artery: Diameter ≥2mm, patent, pliable, no significant stenosis or heavy calcification.
  • Vein: Diameter ≥2.5mm (AVF), ≥4mm (AVG); patent, compressible, continuous with central veins, depth <0.6cm.

  ⭐ Pre-operative duplex ultrasound vessel mapping is crucial; it significantly improves primary AVF patency rates.

• Pre-Op Decision Flow:

Creation to Complications - The Access Journey

• Access Creation:
  • AVF (Arteriovenous Fistula): Gold standard; direct artery-vein anastomosis.
    • Preferred sites (distal first): Radio-cephalic (Brescia-Cimino), Brachio-cephalic, Brachio-basilic (transposed).
  • AVG (Arteriovenous Graft): Synthetic (PTFE) conduit if native veins unsuitable. Higher thrombosis & infection rates.
• Maturation & "Rule of 6s" (📌) (AVF: 4-8 weeks, ideally ~6):
  • Blood Flow: > 600 mL/min.
  • Diameter (vein): > 6 mm.
  • Depth from skin: < 6 mm (for easy cannulation).
  • Cannulatable segment length: > 6 cm.
• Monitoring:
  • Clinical Exam: Palpable thrill, audible bruit (continuous).
  • Duplex Ultrasound: Confirms maturation, measures flow, detects stenosis/patency.
• Complications & Management:

![Types of Dialysis Vascular Access and Complications](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Surgery_Vascular_Surgery_Vascular_Access_for_Hemodialysis/0927481d-2690-46c4-8f17-05fc894d177e.png)
*   **Thrombosis**: Most common failure. Rx: Thrombectomy (surgical/mechanical), thrombolysis.
*   **Stenosis**: Typically venous outflow.
    > ⭐ Juxta-anastomotic venous stenosis is the most common site of stenosis in AVFs.
    *   Rx: PTA (angioplasty) ± stenting.
*   **Infection**: ↑ in AVGs. Local signs (erythema, pus) + systemic (fever). Rx: Antibiotics; graft excision if severe/persistent.
*   **Steal Syndrome**: Distal arterial hypoperfusion. Symptoms: Pain, pallor, paresthesia, ↓pulses. Rx: Banding, DRIL procedure.
*   **Aneurysm/Pseudoaneurysm**: From repeated cannulation/wall weakness. Rx: Surgical repair if symptomatic, large, skin changes, or risk of rupture.
*   **High-Output Cardiac Failure**: Rare; with large, high-flow proximal AVFs.

High‑Yield Points - ⚡ Biggest Takeaways

• Radiocephalic AVF (Brescia-Cimino) is the preferred initial hemodialysis access.
• Rule of 6s for AVF maturity: 6mm diameter, <6mm depth, >600mL/min flow, 6 weeks to use.
• PTFE grafts: use if veins unsuitable; higher infection and thrombosis risk.
• Central venous catheters: for temporary/urgent access; highest infection risk.
• Common complications: stenosis, thrombosis, infection, steal syndrome, aneurysm.
• Palpable thrill and audible bruit indicate AVF patency.