Dialysis Modalities and Renal Replacement Therapies — WACS Viva & Clinical Scenarios (Nephrology)

Exam-style dialysis modalities and renal replacement therapies viva scenarios with examiner probes and model answers for Internal Medicine candidates.

Scenarios covered

• SCENARIO 1: A 42-year-old male with newly diagnosed end-stage renal disease secondary to chronic glomerulonephritis presents to the emergency medical unit with severe lethargy, nausea, a serum urea of 48 mmol/L, serum creatinine of 1150 µmol/L, and serum potassium of 6.8 mmol/L with peaked T waves. He is dialysis-naive. Outline the emergency management, selection and insertion site for temporary vascular access, and formulation of the initial hemodialysis prescription designed to prevent dialysis disequilibrium syndrome.
• SCENARIO 2: A 56-year-old woman established on continuous ambulatory peritoneal dialysis (CAPD) for 14 months presents with diffuse abdominal pain, fever, and cloudy peritoneal effluent. Detail the diagnostic criteria for peritoneal dialysis-associated peritonitis, the standardized laboratory evaluation of the effluent, the empirical intraperitoneal antimicrobial regimen, and the definitive indications for peritoneal catheter removal.
• SCENARIO 3: A 35-year-old male who had a left radiocephalic arteriovenous fistula (AVF) fashioned 8 weeks prior attends the nephrology clinic for pre-dialysis evaluation. Describe the systematic physical examination of an AVF, the clinical and ultrasound criteria defining fistula maturation (Rule of 6s), and the clinical presentation, staging, and therapeutic interventions for dialysis access-associated steal syndrome.
• SCENARIO 4: A 64-year-old woman with septic shock from severe pneumonia develops oliguric acute kidney injury with severe refractory lactic acidosis and fluid overload in the intensive care unit. The multi-disciplinary team elects to initiate continuous renal replacement therapy (CRRT). Compare the biophysical clearance mechanisms of continuous venovenous hemofiltration (CVVH) versus continuous venovenous hemodialysis (CVVHD), write a target effluent prescription, and outline the protocol and safety monitoring for regional citrate anticoagulation.
• SCENARIO 5: A 50-year-old patient on maintenance hemodialysis experiences recurrent intradialytic hypotension and severe lower-limb muscle cramping during the final hour of sessions. Discuss the physiological mechanisms predisposing to intradialytic hypotension, the clinical strategies used to prevent hemodynamic collapse during treatment, and how membrane flux characteristics (low-flux versus high-flux) influence middle molecule clearance and clinical outcomes.