Renal Replacement Therapy — Written Clinical Reasoning

SAQ 1 — Dialysis planning and initiation (12 marks)

Prompt: Outline your approach to dialysis initiation timing, modality selection, and access planning for this man. Justify each decision with evidence. ^{[1] [2]}

Case vignette: A 64-year-old man with CKD stage 5 (eGFR 11, asymptomatic, no refractory hyperkalaemia, acidosis or overload) who lives 90 minutes from the dialysis unit and is interested in home therapy. ^{[1] [2]}

Model Answer

1. Timing of initiation — do not start solely on eGFR (4 marks) ^[1]

The IDEAL trial showed that planned early start at eGFR 10–14 confers no survival advantage over starting at eGFR 5–7 for symptoms or complications. ^[1] His current eGFR of 11 without uraemic symptoms, refractory hyperkalaemia, severe acidosis, or fluid overload is not an automatic start trigger. KDIGO frames initiation as symptom- and complication-driven rather than a fixed eGFR cut-off. ^[2]

I would monitor closely (symptoms, potassium, bicarbonate, fluid status, nutrition) and start when clinical triggers appear: uraemic symptoms, refractory hyperkalaemia or acidosis, diuretic-resistant volume overload, or uraemic pericarditis/encephalopathy. I would still prepare for dialysis now so that when triggers appear he starts electively, not as a crash-lander with a central catheter. ^{[1] [2]}

2. Modality selection — patient-fit, not superiority (4 marks) ^[4]

Observational data show broadly similar survival with haemodialysis and peritoneal dialysis when case-mix is accounted for. ^[4] Selection is therefore by patient preference, residual kidney function, home support, distance from centre, body habitus, prior abdominal surgery, and lifestyle. For this man, living 90 minutes from a unit and interested in home therapy makes PD or home HD attractive if medically suitable. I would offer structured education covering centre HD, home HD, PD (CAPD/APD), and transplant work-up, with transplant first where eligible. ^{[3] [4]}

3. Access planning — fistula-first, protect veins now (4 marks) ^[5]

KDOQI prioritises permanent access and a fistula-first / catheter-last hierarchy where anatomy allows. ^[5] From today: protect the non-dominant arm from venepuncture and cannulae; refer for vascular mapping and surgical planning so an AVF has months to mature if HD is chosen. If PD is chosen, plan elective catheter placement before urgent need. Avoid temporary dialysis catheters when possible — they drive infection and central stenosis. ^[5]