Hemodialysis access
Formal Definition
The vascular access required for hemodialysis — the lifeline for ESRD patients; three main types: arteriovenous fistula (AVF, surgically created connection between artery and vein — preferred), arteriovenous graft (AVG, synthetic bridge when AVF not feasible), and tunneled or non-tunneled central venous catheter (temporary or last resort); each has distinct advantages, complications, and expected longevity, with AVF being the gold standard due to lower infection and thrombosis rates.
How It's Used on the Ward
"Access" — the point of entry for the dialysis machine; the fistula is the gold standard (made from the patient s own vein, lasts years), the graft is synthetic and gets infected more easily, the dialysis catheter is the worst option and usually means you are starting dialysis urgently.
Example
""58-year-old ESRD patient on hemodialysis via left arm AVF for 18 months presents with low dialysis flow rates (220 mL/min, should be >300). Physical exam: firm, non-compressible left arm AVF with a palpable thrill but diminished thrill. Angiography shows proximal stenosis at the AVF venous anastomosis. Diagnosis: AVF stenosis causing insufficient dialysis flows. Referred for percutaneous transluminal angioplasty of the stenosis. Post-PTA flows restored to 380 mL/min with adequate Kt/V.""
Clinical Context
AVF maturation: needs 4-6 weeks (ideally 6-12 months pre-dialysis creation). Maturation criteria: can be cannulated with two needles, delivers flow >600 mL/min, has ≥6mm diameter and >6cm length. AVF monitoring: physical exam (thrill, bruit), flow measurements (FDA guidelines require surveillance), access flow <600 mL/min or recirculation >5% → angiography. AVF complications: thrombosis (most common cause of access loss), stenosis (most common cause of thrombosis — treat with PTA), infection (less common than AVG/catheter). AVG: used when AVF not possible (poor vessels); synthetic PTFE graft; higher infection and stenosis risk than AVF; typically can be used 2-3 weeks post-creation. Catheter: non-tunneled (temporary, high infection, placed in IJ or femoral), tunneled/cuffed (semi-permanent, lower infection than non-tunneled but still highest of all access types). Access preservation: avoid BP measurements and blood draws from the access arm.