Dialysis access types comparison Side-by-side comparison of AV fistula, AV graft, and tunneled catheter showing site, time to use, infection risk, expected lifespan, and clinical preference. AV Fistula Own vein · gold standard AV Graft Synthetic bridge Tunneled Catheter Neck vein · last resort Site Time to use Infection risk Expected life Flow quality Forearm or upper arm 6–12 weeks to mature Very low Years to decades Excellent Forearm or upper arm 2–4 weeks Moderate 2–3 years typical Good Internal jugular / subclavian Immediate High — CRBSI risk Months (temporary) Reduced (recirculation) 1st choice Plan early — needs time 2nd choice When vein quality is poor Bridge / last resort Avoid long-term if possible
AV fistula anatomy diagram Cross-section of the forearm showing radial artery surgically connected to cephalic vein at the anastomosis, with the resulting arterialised vein enlarging for hemodialysis needle insertion. The Rule of 6s criteria are shown at the bottom. Forearm cross-section Radial artery (high pressure) Anastomosis Arterialised cephalic vein (enlarged) Arterial Venous two needles ≥5 cm apart Feel the "thrill" here Rule of 6s — fistula is ready when: flow >600 mL/min · vein diameter >6 mm · depth <6 mm · maturation ≥6 weeks
AV fistula maturation timeline Timeline from fistula surgery through maturation to first cannulation, showing milestones at day 0, week 1, week 4, week 6 rule-of-6s checkpoint, and week 8 plus first use. Warning signs are listed at the bottom. Day 0 Surgery Anastomosis created Wk 1 Wound care Check thrill daily No BP on this arm Wk 4 Vein dilating Exercise arm to promote growth Rule of 6s Wk 6 check Surgeon assesses flow, size, depth Wk 8+ First use Rule of 6s met Buttonhole Report to your surgeon immediately if: thrill disappears · arm swells · site is hot/red · pain on squeezing · fistula feels hard (clot)
Hemodialysis circuit diagram Blood flows from the arterial needle through a blood pump and dialyzer where waste and fluid are removed by countercurrent dialysate, then returns through a bubble trap and venous needle. Heparin is added to prevent clotting in the circuit. Patient AV access in forearm arterial line Blood pump Dialyzer semi-permeable membrane waste + excess fluid dialysate in ↑ dialysate out ↓ ↑ countercurrent Bubble trap venous line Back to arm Heparin drip (prevents clotting) Blood circuit Dialysate (clean) Dialysate (used) Heparin 3.5–5 hours per session · blood flow 300–500 mL/min · 3 sessions per week