PAPER – 2: APPLIED DIALYSIS THERAPY TECHNOLOGY — PART III

MODEL QUESTION PAPER WITH ANSWERS

(Long, Short & Very Short Questions — All 9 Units Covered)

SECTION A — LONG ANSWER QUESTIONS (LAQ) (10 marks each)

Unit 1: Introduction to Peritoneal Dialysis

• The peritoneum as a dialyzing membrane was first described in the early 20th century.
• Georg Ganter (1923) performed the first successful peritoneal irrigation in a human.
• Maxwell et al. (1959) reported the use of intermittent peritoneal dialysis (IPD) for acute renal failure.
• Tenckhoff and Schechter (1968) introduced the permanent indwelling silicone catheter, enabling chronic PD.
• Popovich and Moncrief (1976) conceived Continuous Ambulatory Peritoneal Dialysis (CAPD).
• In the 1980s, automated (cycler-assisted) PD became available, giving rise to APD/CCPD.

1. Diffusion: Governed by Fick's first law. Solute moves down a concentration gradient. Rate depends on membrane permeability, surface area, and concentration difference. Small molecules (urea, creatinine) diffuse rapidly; large molecules (proteins) diffuse slowly.
2. Convection (Ultrafiltration): Occurs when a hyperosmotic dialysate (e.g., 2.5% or 4.25% dextrose) creates an osmotic gradient, drawing water from capillaries into the peritoneal cavity. Solutes move along with this water flux (solvent drag).
3. Three-Pore Model of Peritoneal Transport:
   • Large pores (>150 Å): albumin and macromolecule transport
   • Small pores (40–45 Å): small solute transport (urea, creatinine, electrolytes)
   • Ultra-small pores / aquaporin-1 channels (2–5 Å): free water transport

• Mesothelial cell layer with microvilli
• Basement membrane
• Interstitium (fibroblasts, collagen, glycosaminoglycans)
• Capillary endothelium

• End-stage renal disease (ESRD/ESKD) with GFR <10 mL/min/1.73 m²
• Patient preference for home-based therapy
• Lack of vascular access for hemodialysis
• Cardiovascular instability (not tolerating HD)
• Children and elderly patients
• Residual renal function preservation
• Diabetic patients (insulin can be given intraperitoneally)
• Remote location from HD center

• Used in acute kidney injury (AKI), hyperkalemia, severe metabolic acidosis, or fluid overload when HD is unavailable or contraindicated.
• Performed using a rigid stylet catheter or soft catheter placed percutaneously.
• Exchanges of 1–2 L are performed every 1–2 hours.
• Advantages: Simple, no blood circuit, no anticoagulation, hemodynamically gentle, cheap.
• Disadvantages: Slow clearance, risk of peritonitis, respiratory compromise, protein loss, limited in hypercatabolic states.

Unit 3: PD Process and Evaluation of Peritoneum

• Kt/V urea ≥ 1.7/week (combined peritoneal + residual renal) — ISPD minimum target
• Weekly CCr ≥ 50 L/week/1.73 m² for high/high-average transporters

• Performed with 2 L of 2.27% dextrose dialysate
• Measures D/P creatinine (dialysate-to-plasma ratio) and D/D0 glucose at 4 hours
• Classifies patients as:
  • High transporters: D/P Cr >0.81 — fast solute transport, poor UF; best on APD/NIPD
  • High-average: D/P Cr 0.65–0.81
  • Low-average: D/P Cr 0.50–0.64
  • Low transporters: D/P Cr <0.50 — slow transport, better UF; best on CAPD

Unit 4: PD Complications and Management

• Dialysate leak (pericatheter, abdominal wall, pleural)
• Catheter tip migration / malposition
• Outflow failure (constipation, fibrin, omental capture)
• Hernia (inguinal, umbilical, incisional)
• Hemorrhagic effluent / hemoperitoneum
• Infusion pain / jet effect

• Hyperglycemia (from dextrose absorption)
• Hypertriglyceridemia
• Protein loss and malnutrition
• Ultrafiltration failure
• Encapsulating peritoneal sclerosis (EPS)

1. Peritonitis — Most common; usually bacterial
2. Exit site infection (cellulitis ≤2 cm from exit site)
3. Tunnel infection (>2 cm from exit site, involves subcutaneous tract)
4. Catheter-related bacteremia

• Cloudy effluent + WBC >100 cells/µL (>50% neutrophils) in dialysate
• Abdominal pain, fever
• Culture of dialysate (identify organism)

• Empiric antibiotics (intraperitoneal or IV):
  • Gram-positive coverage: Vancomycin or 1st generation cephalosporin (cefazolin)
  • Gram-negative coverage: 3rd gen cephalosporin (ceftazidime) or aminoglycoside
• Duration: 14–21 days depending on organism
• If fungi: Remove catheter + antifungal therapy
• Catheter removal if refractory peritonitis >5 days, fungal, or fecal organisms
• Post-peritonitis PET after 4–6 weeks to reassess membrane

Unit 5 & 6: Systemic and Infectious Diseases in Dialysis Patients

• Dextrose-based dialysate causes ~100–200 g glucose absorption/day → hyperglycemia
• Monitor blood glucose frequently; may require increased insulin doses
• Insulin can be given intraperitoneally (IP insulin preferred in CAPD for steady glucose control)
• IP insulin dose = 2–4× subcutaneous dose
• Use of icodextrin (7.5%) for long dwell reduces glucose load
• Diabetic nephropathy patients on PD have higher cardiovascular mortality; strict glycemic control reduces complications
• Target HbA1c: <7% where possible (adjusted for red cell survival on dialysis)

• Often volume-dependent; proper ultrafiltration is key
• Dietary sodium restriction + adequate UF to achieve euvolemia
• Antihypertensives: ACE inhibitors / ARBs (protect residual renal function), calcium channel blockers
• Avoid NSAIDs (decrease residual renal function)
• Monitor BP and fluid status at each visit

• Anemia: Normocytic normochromic; due to EPO deficiency, iron deficiency, protein loss, chronic inflammation
  • Treatment: Erythropoiesis-stimulating agents (ESA), IV/oral iron supplementation
  • Hb target: 10–12 g/dL
• Thrombocytopenia: May occur with uremia
• Leukocytosis/Lymphopenia: Immune dysregulation in CRF
• Coagulopathy: Platelet dysfunction in uremia → bleeding tendency; corrected by dialysis adequacy, DDAVP, conjugated estrogens

• Prevalence higher in dialysis units than general population (immunosuppression, multiple blood exposures)
• Transmission: Blood-to-blood contact, shared equipment
• Prevention: HBV vaccination mandatory for all dialysis patients (4-dose series, 40 µg/dose); check anti-HBs annually
• HBsAg+ patients: Isolated machines and bays; dedicated staff
• Treatment: Tenofovir or entecavir (dose-adjusted for GFR)
• Vaccination response is lower in dialysis patients (~50–60%)

• Most common chronic viral hepatitis in dialysis units
• Transmission: Nosocomial via shared dialysis equipment
• Screening: Anti-HCV + HCV RNA (NAT) every 6 months
• Isolation is controversial; strict infection control is essential
• Treatment: Direct-acting antivirals (DAAs) — ledipasvir/sofosbuvir, glecaprevir/pibrentasvir (renal-adjusted dose)
• SVR rates >95% with modern DAAs

• Risk from blood exposures; universal precautions mandatory
• HIV-associated nephropathy (HIVAN) is a common cause of ESRD in HIV+ patients
• ART (antiretroviral therapy) should be continued during dialysis; dose adjustment required for some agents
• Standard precautions; no need for isolation if viral load undetectable

• Most common organism: Staphylococcus aureus (gram-positive); also gram-negative organisms
• Diagnosis: Blood cultures from catheter hub AND periphery
• Management:
  • Empiric antibiotics: Vancomycin (gram-positive) + aminoglycoside/cephalosporin (gram-negative)
  • Tunneled catheters: Attempt catheter salvage with antibiotic lock therapy if uncomplicated
  • Remove catheter if: Persistent bacteremia >72 hrs, tunnel infection, metastatic complications (endocarditis, osteomyelitis), fungal bacteremia
  • Replace catheter at different site after infection resolved

SECTION B — SHORT ANSWER QUESTIONS (SAQ) (5 marks each)

• Large pores (>150 Å): Low number; transport albumin and macromolecules
• Small pores (40–45 Å): Majority; transport small solutes (urea, creatinine, Na⁺, K⁺) by diffusion
• Ultra-small pores / aquaporin-1 (2–5 Å): Transcellular water channels; responsible for ~40% of free water transport during osmotic UF

• Tenckhoff catheter (straight / curled tip)
• Swan-neck catheter (pre-bent at 150° angle)
• Toronto Western Hospital catheter (with two silicone discs preventing migration)
• Missouri catheter
• Pre-sternal catheter

• Most widely used PD catheter
• Silicone rubber, 30 cm long with side holes at the tip for fluid inflow/outflow
• Has 1 (single-cuff) or 2 (double-cuff) Dacron cuffs — one placed within rectus muscle, one subcutaneous
• Cuffs anchor the catheter and prevent bacterial ingress
• Straight tip vs. curled (pigtail) tip — curled tip reduces migration
• Inserted by surgical dissection, laparoscopic, or percutaneous (trocar/Seldinger) technique
• Allowed to heal for 2–4 weeks before use (elective implant)

• Dialysis adequacy measures how effectively waste products are removed.
• For PD: Weekly Kt/V urea ≥ 1.7 (peritoneal + residual renal) is the ISPD target.
• Kt/V = (V × ln[Co/C] + UF × C_mean) / V (formal formula)
• Practical calculation: Collect 24-hour urine AND 24-hour PD effluent → measure urea in each + serum urea
  • Kt/V (PD) = [(D/P urea × dialysate volume drained) / total body water (V)] × 7
• Total body water (V) estimated by Watson formula (based on height, weight, age, sex)

• Technique training: Proper hand washing, aseptic exchange procedure, connecting/disconnecting transfer set
• Exit site care: Daily cleaning with antiseptic solution, sterile dressing
• Signs of peritonitis: Recognizing cloudy effluent, abdominal pain, fever → immediate reporting
• Diet & fluid management: Sodium, potassium, phosphate restriction; adequate calorie and protein intake
• Medication compliance: Phosphate binders, antihypertensives, EPO injections
• Monitoring: Daily weight, blood pressure, ultrafiltration volume, fluid balance diary
• Emergency contacts: Know when and how to contact the dialysis team

• Dialysis patients are at high risk for protein-energy wasting (PEW) due to reduced dietary intake, dialysate protein losses (5–15 g/day in PD), inflammation, and metabolic acidosis.
• Protein requirement: 1.2–1.3 g/kg/day for PD patients (higher than HD due to dialysate losses)
• Caloric requirement: 30–35 kcal/kg/day (subtract dextrose calories from dialysate ~300–800 kcal/day)
• Nutritional assessment: Subjective Global Assessment (SGA), Malnutrition Inflammation Score (MIS)
• Potassium: Restrict if hyperkalemic
• Phosphorus: Restrict; use phosphate binders with meals
• Water-soluble vitamins (B-complex, C) supplemented due to losses through dialysate
• If oral intake inadequate → oral nutritional supplements → intradialytic parenteral nutrition (IDPN) or intraperitoneal amino acid (IPAA) solutions

• Sources: Aluminium-containing phosphate binders (aluminium hydroxide), contaminated dialysis water
• Manifestations:
  • Dialysis encephalopathy (dementia, speech disorder, myoclonus, seizures)
  • Aluminium-related bone disease (osteomalacia)
  • Microcytic anaemia (iron-resistant)
• Diagnosis: Serum aluminium >60 µg/L (baseline); desferrioxamine (DFO) stimulation test — rise >50 µg/L confirms toxicity
• Treatment: Remove aluminium-containing binders; DFO chelation therapy (weekly IV/IP infusions); maintain water aluminium <10 µg/L

• Leading cause of death in dialysis patients (~50% of all deaths)
• Risk factors: Hypertension, volume overload, LVH, dyslipidemia, hyperphosphatemia, vascular calcification, anemia, elevated homocysteine, CRP
• Left ventricular hypertrophy (LVH): Present in >70% of patients starting dialysis; volume/pressure overload
• Ischemic heart disease: Accelerated atherosclerosis
• Heart failure: Both systolic and diastolic
• Pericarditis: Uremic pericarditis (uremic toxins) or dialysis-associated pericarditis (inadequate dialysis)
• Arrhythmias: Electrolyte disturbances (K⁺, Ca²⁺), uremia
• Management: Strict volume control (UF), BP control, statins, EPO, optimal dialysis adequacy, echocardiographic monitoring

• ESWL is a non-invasive procedure for kidney and ureteral stones
• Principle: High-energy shock waves focused on the stone break it into small fragments that pass in urine
• Indications: Renal calculi <2 cm, proximal ureteral stones
• Contraindications: Pregnancy, uncorrected bleeding disorders, distal obstruction, pacemaker, morbid obesity
• Procedure: Patient positioned; fluoroscopy or ultrasound used to locate stone; 1500–3000 shocks delivered
• Complications: Hematuria, renal hematoma, perirenal bruising, sepsis (if infected stone), Steinstrasse (stone fragments blocking ureter)
• Post-procedure: Encourage fluid intake; strain urine for stone fragments; follow-up KUB/ultrasound

• ICU patients with AKI who are hemodynamically unstable require CRRT rather than conventional HD
• Modalities:
  • CVVH (Continuous Venovenous Hemofiltration) — convection
  • CVVHD (Continuous Venovenous Hemodialysis) — diffusion
  • CVVHDF — combination of both
• Advantages over HD in ICU: Gradual fluid removal, hemodynamic stability, better control of fluid balance, continuous solute removal
• Anticoagulation: Regional citrate anticoagulation (preferred) or systemic heparin
• Access: Temporary non-tunneled double-lumen CVC (femoral, internal jugular, or subclavian)
• Indications: Volume overload, hyperkalemia, severe metabolic acidosis, uremia, drug toxicity

SECTION C — VERY SHORT ANSWER QUESTIONS (VSQ) (2 marks each)

1. Q: Who introduced the Tenckhoff catheter and when? - Henry Tenckhoff, 1968
2. Q: What is the surface area of the peritoneal membrane? - 1.6–2.0 m² (up to 40 m² with microvilli)
3. Q: Name two mechanisms of solute transport in PD. - Diffusion and Convection (Ultrafiltration)
4. Q: What drives ultrafiltration in peritoneal dialysis? - Osmotic gradient created by dextrose in dialysate
5. Q: Define acute peritoneal dialysis. - PD performed for acute kidney injury using short dwell exchanges, often with rigid or temporary catheters

QUICK REVISION TABLE — KEY FACTS FOR MCQs