Renal Replacement Therapy (RRT)

1. Clinical Overview

Summary

Renal Replacement Therapy (RRT) encompasses all modalities that substitute for the non-endocrine functions of the kidney in patients with acute kidney injury (AKI) or end-stage renal disease (ESRD). The primary functions replaced include solute clearance (removal of nitrogenous waste products), fluid balance regulation, and acid-base homeostasis. [1,2]

The three principal modalities are:

• Haemodialysis (HD): Extracorporeal blood purification using diffusive and convective solute removal across a semipermeable membrane. Usually performed in-centre 3 times weekly for 4 hours. [3]
• Peritoneal Dialysis (PD): Uses the peritoneal membrane as a dialyzer, with dialysate dwelling in the peritoneal cavity. Can be performed as continuous ambulatory PD (CAPD) or automated PD (APD) at home. [4]
• Kidney Transplantation: Definitive treatment providing the best long-term outcomes and quality of life. Includes living donor and deceased donor grafts. [5]
• Continuous Renal Replacement Therapy (CRRT): Slow continuous extracorporeal therapy used primarily in ICU settings for hemodynamically unstable patients with AKI. [6]

Epidemiology

Global Burden:

• Worldwide, approximately 2.6 million people receive RRT
• Incidence rising by 7% annually, driven primarily by diabetes and hypertension [1]
• Significant global disparities: high-income countries have 10-fold higher RRT access than low-income nations

UK Statistics:

• ~65,000 patients on RRT (prevalence ~1,000 per million population)
• Distribution: 50% transplant, 40% haemodialysis, 10% peritoneal dialysis [2]
• Median age at RRT initiation: 64.5 years
• Primary causes: diabetic nephropathy (29%), hypertensive nephrosclerosis (13%), glomerulonephritis (11%)

Outcomes:

• 5-year survival: Transplant 90%, PD 50%, HD 45% [5]
• Cardiovascular disease remains the leading cause of death (40-50% of dialysis patients) [7]

Clinical Pearls

The "AEIOU" of Acute Dialysis Initiation:

When to initiate emergency RRT in AKI:

• Acidosis: pH less than 7.15 despite medical therapy (bicarbonate infusion)
• Electrolytes: Hyperkalaemia K⁺ > 6.5 mmol/L refractory to medical management
• Intoxication: Dialyzable toxins (lithium, salicylates, ethylene glycol, methanol)
• Overload: Pulmonary oedema refractory to diuretics
• Uraemia: Uraemic complications (pericarditis, encephalopathy, bleeding) typically urea > 30-50 mmol/L [8]

Fistula First, Catheter Last:

The arteriovenous fistula (AVF) is the patient's "lifeline" and must be zealously protected:

• NEVER allow blood pressure measurement on the fistula arm
• NEVER allow venepuncture or IV cannulation on the fistula arm
• Preservation of arm veins (especially cephalic vein) is crucial in pre-dialysis CKD patients
• Educate all clinical staff about fistula protection protocols [9]

Timing of Dialysis Initiation in CKD:

The IDEAL trial (2010) demonstrated no benefit to "early-start" dialysis (eGFR 10-14 mL/min) versus "late-start" (eGFR 5-7 mL/min). Current practice: initiate based on symptoms and complications, not purely on eGFR thresholds. [10]

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2. Principles of Dialysis

Fundamental Mechanisms

1. Diffusion (Clearance)

Movement of solutes down a concentration gradient across a semipermeable membrane from blood (high concentration) to dialysate (low concentration). Governed by Fick's law of diffusion.

• Rate depends on: Concentration gradient, membrane surface area, membrane permeability, molecular weight
• Removes: Small molecules (urea MW 60 Da, creatinine MW 113 Da, potassium MW 39 Da)
• Used in: Both HD and PD [11]

2. Convection (Solvent Drag)

Water is pushed across the membrane by hydrostatic or osmotic pressure, dragging solutes with it by "solvent drag." Independent of concentration gradients.

• Rate depends on: Transmembrane pressure, membrane permeability, molecular size
• Removes: Larger molecules up to middle molecules (β2-microglobulin MW 11,800 Da, cytokines)
• Used in: Haemofiltration (CVVH), high-flux HD, haemodiafiltration [6]

3. Ultrafiltration (Fluid Removal)

Net movement of water across the membrane driven by pressure gradients.

• Haemodialysis: Transmembrane pressure (TMP) = hydrostatic pressure difference across membrane. Negative pressure applied to dialysate compartment creates suction.
• Peritoneal Dialysis: Osmotic pressure gradient. Glucose in dialysate creates osmotic force drawing water from peritoneal capillaries. Higher glucose concentration (1.36%, 2.27%, 3.86%) = greater ultrafiltration. [4,11]

4. Adsorption

Some solutes bind to the dialysis membrane surface (protein-bound toxins, endotoxins). More important with certain membrane types (polysulfone, polyacrylonitrile).

Adequacy Monitoring

Kt/V: The Universal Dialysis Dose Metric [12]

• K = dialyzer urea clearance (mL/min)
• t = treatment time (minutes)
• V = urea distribution volume (total body water in mL)
• Kt/V = dimensionless number representing fractional urea clearance

Targets:

• Haemodialysis: Single-pool Kt/V ≥ 1.2 per session (KDOQI), ≥ 1.4 preferred
• Peritoneal Dialysis: Weekly Kt/V ≥ 1.7
• Residual renal function: Contributes significantly to total clearance in PD patients; preservation is crucial

Alternative Measures:

• Urea Reduction Ratio (URR): (Pre-dialysis urea - Post-dialysis urea) / Pre-dialysis urea × 100. Target ≥65%
• Online clearance monitoring (OCM): Real-time ionic dialysance measurement during HD [12]

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3. Modality 1: Haemodialysis (HD)

Procedure Overview

Circuit Components:

1. Vascular access (fistula, graft, or catheter)
2. Blood pump (typical flow 250-450 mL/min)
3. Heparinization (to prevent clotting in extracorporeal circuit)
4. Dialyzer (hollow-fiber artificial kidney)
5. Dialysate delivery system
6. Air detector and clot monitor
7. Blood return to patient [3]

Standard Prescription:

• Frequency: 3 sessions per week
• Duration: 4 hours per session (range 3.5-5 hours)
• Blood flow rate: 300-400 mL/min
• Dialysate flow rate: 500-800 mL/min
• Ultrafiltration rate: Based on interdialytic weight gain (typically 0.5-1.5 L per hour maximum)

Dialysate Composition (Typical):

• Sodium: 135-145 mmol/L (individualized)
• Potassium: 0-4 mmol/L (adjusted to patient needs)
• Calcium: 1.25-1.50 mmol/L
• Bicarbonate: 32-38 mmol/L (acid-base buffer)
• Glucose: 5-11 mmol/L

Vascular Access: The Achilles Heel of Haemodialysis [9,13]

1. Arteriovenous Fistula (AVF) - The Gold Standard

Surgical Technique:

• Radiocephalic (Brescia-Cimino): Radial artery to cephalic vein at wrist. Most common, longest lifespan.
• Brachiocephalic: Brachial artery to cephalic vein at elbow. Larger diameter, higher flow.
• Brachiobasilic: Brachial artery to basilic vein. Requires vein transposition (basilic is too deep).

Maturation Process:

• Requires 6-12 weeks for "arterialization" of vein
• Flow increases from 50 mL/min → 500-1000 mL/min
• Vein wall thickens, dilates to 5-6mm diameter
• Rule of Sixes: Ready when ≥6mm diameter, ≤6mm depth, ≥600 mL/min flow [13]

Clinical Examination:

• Inspection: Visible pulsation, dilatation, surgical scars
• Palpation: Continuous thrill (buzzing/purring sensation). Loss of thrill = EMERGENCY (suggests thrombosis)
• Auscultation: Continuous machinery murmur (bruit). High-pitched bruit suggests stenosis.
• Distal circulation: Check radial pulse, capillary refill (exclude steal syndrome)

Advantages:

• Longest patency (5-year primary patency 60-70%)
• Lowest infection risk
• Highest blood flow rates
• No foreign material

Complications:

• Early (Failure to Mature): 20-50% primary failure rate. Risk factors: female sex, diabetes, elderly, small vessels, previous IV cannulation.
• Stenosis: Usually juxta-anastomotic. Presents with reduced dialysis adequacy, prolonged bleeding, high venous pressure. Requires surveillance (flow monitoring, access recirculation).
• Thrombosis: Presents as sudden loss of thrill/bruit. URGENT thrombectomy within 24-48 hours may salvage access.
• Aneurysm Formation: True aneurysm (all vessel layers) vs pseudoaneurysm. Risk of rupture if skin thinning.
• Steal Syndrome: Fistula "steals" arterial blood from distal limb → cold, painful, pale fingers. Severe cases → digital necrosis. Requires access revision or ligation.
• High-output cardiac failure: Massive fistula flow (> 2 L/min) rarely causes high-output heart failure in patients with pre-existing cardiac dysfunction. [9,13]

2. Arteriovenous Graft (AVG)

Indications:

• Inadequate veins for native AVF
• Previous AVF failures
• Urgent need for access (matures in 2-4 weeks vs 6-12 weeks for AVF)

Materials:

• Polytetrafluoroethylene (PTFE): Most common synthetic graft
• Bovine/porcine grafts: Biological alternatives

Configuration:

• Forearm loop, upper arm straight, or thigh grafts

Outcomes:

• Primary patency: 1-year 50%, 2-year 30% (inferior to AVF)
• Infection risk: 10-fold higher than AVF
• Stenosis: Venous anastomosis most common site (intimal hyperplasia)
• Surveillance: Regular monitoring required; earlier intervention improves patency [9]

3. Central Venous Catheter (CVC) - "Permcath"

Types:

• Non-tunneled (temporary): Inserted at bedside. Femoral, internal jugular, or subclavian sites. Maximum duration 2-3 weeks.
• Tunneled (Permcath): Surgically placed with subcutaneous cuff (dacron). Usually internal jugular vein. Intended for months. [3]

Advantages:

• Immediate use (no maturation required)
• No needles (useful for needle-phobic patients)
• Useful as bridge while AVF/AVG matures

Disadvantages:

• Infection: Catheter-related bloodstream infection (CRBSI) rate 2-5 per 1000 catheter-days. Leading cause of bacteraemia in dialysis patients. Organisms: Staphylococcus aureus, coagulase-negative staphylococci.
• Central vein stenosis/thrombosis: 30-50% risk. Can preclude future ipsilateral AVF/AVG and transplantation.
• Inadequate blood flow: Lower flow rates (250-350 mL/min) vs AVF/AVG (400-500 mL/min). Recirculation reduces dialysis efficiency.
• Thrombosis: Requires thrombolytics or exchange.

Catheter Care:

• Exit site must be kept clean and dry
• Locked with heparin or citrate between dialysis sessions
• Antiseptic protocols reduce infection (chlorhexidine superior to povidone-iodine)

Home Haemodialysis

Advantages:

• Greater flexibility and autonomy
• More frequent/longer sessions possible (5-6x/week or nocturnal)
• Better biochemical control, BP control, symptom burden
• Improved quality of life and patient satisfaction [3]

Requirements:

• Patient motivation and capability (or trained helper)
• Suitable home environment (space, plumbing, electrical supply)
• Machine installation and water treatment system
• Emergency protocols and backup plans

Outcomes:

• Observational studies suggest improved survival vs conventional in-centre HD
• Particularly beneficial for younger patients with long life expectancy

Complications of Haemodialysis

Intradialytic Complications:

Hypotension (20-30% of sessions):

• Mechanisms: Excessive ultrafiltration, impaired vascular refilling, autonomic dysfunction, reduced cardiac output
• Management: Reduce UF rate, Trendelenburg position, hypertonic saline, review dry weight [3]

Muscle Cramps (5-20% of sessions):

• Mechanism: Uncertain (? hypovolaemia, electrolyte shifts, tissue hypoxia)
• Management: Reduce UF rate, hypertonic saline, quinine sulfate (controversial), stretching

Dialysis Disequilibrium Syndrome:

• Occurs in newly initiated patients or after prolonged missed sessions
• Mechanism: Rapid urea removal from plasma → reverse urea gradient → water influx into brain → cerebral oedema
• Presentation: Headache, nausea, confusion, seizures (severe cases)
• Prevention: Short (2-hour) initial sessions, low blood flow rates (150-200 mL/min), gradual increase in dose [8]

Air Embolism:

• Rare but potentially fatal
• Entry of air into venous circuit → pulmonary embolism or paradoxical arterial embolism
• Prevention: Air detectors, meticulous technique
• Management: Left lateral decubitus + Trendelenburg position, 100% oxygen, hyperbaric oxygen (if available)

Long-term Complications:

Dialysis-Related Amyloidosis (DRA):

• Accumulation of β2-microglobulin (MW 11,800 Da) poorly cleared by conventional low-flux dialysis
• Deposits in bones, joints, tendons
• Presentation: Carpal tunnel syndrome, trigger finger, shoulder pain (rotator cuff), destructive arthropathy, pathological fractures
• Typically develops after 5-10 years on dialysis
• Prevention: High-flux dialysis membranes improve clearance; transplantation is curative [7]

Cardiovascular Disease:

• 10-20 fold increased cardiovascular mortality vs general population
• Accelerated atherosclerosis, left ventricular hypertrophy, vascular calcification
• Mechanisms: Chronic inflammation, oxidative stress, mineral-bone disease (hyperphosphataemia → vascular calcification), volume overload
• Management: BP control, volume management, phosphate binders, statins (benefit less clear than in non-dialysis population) [7]

Acquired Cystic Kidney Disease and Renal Cell Carcinoma:

• Cysts develop in native kidneys in 40% after 3 years dialysis, 80% after 10 years
• 4-7 fold increased risk of renal cell carcinoma
• Surveillance: Some advocate annual renal USS in long-term dialysis patients

Hepatitis B and C:

• Nosocomial transmission previously common (contaminated equipment, inadequate infection control)
• Modern protocols (dedicated machines, strict hygiene) have dramatically reduced transmission
• All dialysis patients should receive hepatitis B vaccination

Pros and Cons Summary

Advantages:

• Efficient solute clearance (4 hours achieves weekly clearance target)
• Supervised by trained nursing staff (less patient responsibility than PD)
• Social contact with other patients and staff
• Suitable for patients unable to perform home therapy

Disadvantages:

• Hospital attendance 3x weekly (12+ hours/week including travel)
• Fixed schedule reduces flexibility
• "Washout" fatigue post-dialysis (uraemic toxin rebound, volume shifts)
• Haemodynamic instability (hypotension, cramps)
• Strict fluid restriction (typically 800-1000 mL/day) and dietary phosphate restriction
• Vascular access complications

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4. Modality 2: Peritoneal Dialysis (PD)

Physiology and Principles

The Peritoneal Membrane as Dialyzer:

• Surface area: 1-2 m² (approximates body surface area)
• Three-pore model: Small pores (water, small solutes), large pores (proteins, macromolecules), aquaporins (water-only channels)
• Peritoneal capillaries separated from peritoneal cavity by: capillary endothelium, interstitium, mesothelium
• Effective peritoneal surface area determined by capillary density, blood flow

Transport Characteristics (PET - Peritoneal Equilibration Test): [4]

• High transporters: Rapid solute equilibration, rapid glucose absorption → poor UF. Short dwells preferred.
• Low transporters: Slow solute equilibration, slow glucose absorption → excellent UF but poor clearance. Long dwells preferred.
• High average/Low average: Intermediate characteristics. Most patients fall here.

Procedure and Prescription

Tenckhoff Catheter Insertion:

• Surgically placed under general/local anaesthesia
• Enters peritoneal cavity in midline, usually infraumbilically
• Intraperitoneal portion has multiple side-holes for fluid exchange
• Subcutaneous tunnel with one or two dacron cuffs (tissue ingrowth, barrier to infection)
• Exit site usually lateral to midline (prevents catheter kinking when sitting) [4]

Modalities:

1. Continuous Ambulatory Peritoneal Dialysis (CAPD):

• Manual exchanges 4 times daily (morning, lunchtime, evening, bedtime)
• Each exchange: Drain out old fluid (20-30 min) → Infill new fluid (10 min) → Dwell (4-6 hours)
• Typical prescription: 2-2.5 litres per exchange, 8-10 L total daily volume
• Patient must be mobile and have manual dexterity

2. Automated Peritoneal Dialysis (APD) / Continuous Cycling PD (CCPD):

• Cycler machine performs exchanges overnight (typically 8-10 hours)
• Multiple short dwells (1-2 hours) overnight
• Often includes daytime dwell
• Advantages: No daytime exchanges, suitable for working patients, less physical burden
• Requires: Space for machine, electricity supply, storage for supplies

Dialysate Solutions:

Osmotic Agents:

• Glucose: Standard agent. Concentrations 1.36% (weak), 2.27% (medium), 3.86% (strong). Higher concentration → greater UF. Disadvantages: Hyperglycaemia (especially in diabetics), peritoneal membrane damage (glucose degradation products), weight gain, metabolic complications.
• Icodextrin (7.5%): Glucose polymer. Once-daily long-dwell (8-16 hours). Sustained UF via colloid osmosis. Particularly useful in high transporters or diabetics. Cannot use more than once per day (accumulation).
• Amino acids (1.1%): Nutritional supplementation + osmotic agent. Useful in malnourished patients. Usually one exchange per day. [4]

Biocompatible Solutions:

• Conventional solutions: Low pH (5.2-5.5), high glucose degradation products (GDP), lactate buffer
• Biocompatible solutions: Neutral pH (7.0-7.4), low GDP (dual-chamber bag system), bicarbonate buffer
• Benefits: Better preservation of peritoneal membrane, reduced peritonitis risk, improved UF

Complications of Peritoneal Dialysis

1. Peritonitis - The Achilles Heel of PD [14]

Epidemiology:

• Rate: Target less than 0.5 episodes per patient-year (ISPD guidelines)
• Accounts for 15-20% of PD technique failure
• Contributes to 2-6% mortality in PD patients

Causative Organisms:

• Gram-positive (60-70%): Staphylococcus epidermidis (skin flora from touch contamination), Staphylococcus aureus, Streptococcus species
• Gram-negative (20-30%): E. coli, Pseudomonas, Klebsiella (often bowel flora, suggests GI source)
• Fungal (2-10%): Candida species. Poor prognosis, usually requires catheter removal
• Culture-negative (10-20%): Prior antibiotic use, inadequate culture technique, atypical organisms

Presentation:

• Cloudy effluent (> 100 white cells/μL with > 50% polymorphs) - Hallmark sign
• Abdominal pain: Diffuse or generalized, exacerbated by infusion
• Fever: Present in 30-40%, absence does not exclude peritonitis
• Nausea/vomiting: Common
• Diarrhoea: May indicate bowel source

Diagnosis:

• Effluent cell count: WCC > 100/μL with > 50% neutrophils (diagnostic)
• Gram stain and culture: Send immediately (BEFORE antibiotics). Use blood culture bottles for better yield.
• Cloudy bag appearance: If cloudy bag + abdominal pain, start empirical antibiotics immediately

ISPD Treatment Protocol (2016): [14]

• Empirical therapy (while awaiting cultures): Vancomycin (Gram-positive cover) + Ceftazidime OR Aminoglycoside (Gram-negative cover). Intraperitoneal route preferred.
  • "Vancomycin: Loading 15-30 mg/kg IP, maintenance 15-25 mg/kg every 5-7 days"
  • "Ceftazidime: Loading 500 mg/L, maintenance 125 mg/L per exchange"
  • "Gentamicin: Loading 8 mg/L, maintenance 4 mg/L per exchange"
• Adjust based on culture: De-escalate to narrow-spectrum once organism identified
• Duration:
  • "Coagulase-negative staphylococci: 14 days"
  • "S. aureus: 21 days (high relapse risk)"
  • "Pseudomonas: 21 days (add oral quinolone)"
  • "Fungal: REMOVE CATHETER immediately, systemic antifungals, wait 2-4 weeks before new catheter"

Indications for Catheter Removal:

• Fungal peritonitis
• Refractory peritonitis (no improvement after 5 days appropriate antibiotics)
• Relapsing peritonitis (same organism less than 4 weeks after treatment)
• Mycobacterial peritonitis
• Catheter-related infection with tunnel/exit site involvement

Prevention Strategies:

• Meticulous aseptic technique training
• Prophylactic mupirocin cream to nares (eradicates S. aureus carriage)
• Exit site mupirocin or gentamicin cream daily
• "Flush before fill" technique
• Prophylactic antibiotics at time of catheter insertion, dental procedures, colonoscopy

2. Catheter-Related Complications

Exit Site Infection:

• Purulent drainage from exit site ± erythema, tenderness
• Organisms: S. aureus (most common), Pseudomonas
• Treatment: Oral antibiotics (2-3 weeks). If Pseudomonas or S. aureus with tunnel involvement → catheter removal often required.
• Prevention: Daily exit site care, topical mupirocin/gentamicin

Tunnel Infection:

• Erythema, tenderness, oedema along subcutaneous tunnel
• Often requires catheter removal
• Ultrasound can assess tunnel if clinical examination equivocal

Catheter Malfunction:

• Inflow/outflow obstruction: Fibrin, omentum wrapping, catheter malposition
• Management: Heparin flushes (for fibrin), laxatives (constipation can compress catheter), fluoroscopy-guided repositioning, laparoscopic adhesiolysis

Pericatheter Leak:

• Dialysate leaking around exit site or into abdominal wall
• Risk factors: Immediate use after insertion (should wait 2 weeks), obesity, large fill volumes
• Management: Temporary HD or rest from PD (allow healing), reduce fill volumes, rarely requires surgical repair

3. Mechanical Complications

Hernias:

• Prevalence: 15-25% of PD patients
• Types: Inguinal (most common), umbilical, incisional, femoral
• Mechanism: Increased intraperitoneal pressure
• Management: May require surgical repair. Temporary HD while recovering. Consider smaller fill volumes when resume PD.

Hydrothorax:

• Dialysate crosses diaphragm → pleural effusion (usually right-sided)
• Presents with dyspnoea, reduced UF
• Diagnosis: Glucose concentration in pleural fluid >> serum (confirms dialysate)
• Management: Temporary HD, pleurodesis, rarely successful to resume PD

Encapsulating Peritoneal Sclerosis (EPS):

• Rare (0.5-2.5%) but devastating complication
• Inflammation → peritoneal fibrosis → "cocooning" of bowel → intestinal obstruction
• Risk factors: Duration on PD (especially > 5-8 years), recurrent peritonitis, high glucose exposure
• Presentation: Recurrent small bowel obstruction, malnutrition, ascites (bloody or cloudy)
• Diagnosis: CT abdomen (peritoneal thickening, calcification, bowel tethering)
• Management: STOP PD immediately, transfer to HD. Nutritional support (often TPN). Immunosuppression (tamoxifen, corticosteroids) - evidence limited. Surgical peritonectomy in selected cases.
• Mortality: 50-70% within 1-2 years of diagnosis [4,14]

4. Metabolic Complications

Glucose Absorption:

• 100-200g glucose absorbed daily from dialysate
• Consequences: Weight gain, hyperglycaemia, dyslipidaemia, metabolic syndrome
• Management: Icodextrin for long-dwell, diabetic control optimization

Protein Loss:

• 5-15g protein lost daily in effluent (increased during peritonitis)
• Risk of malnutrition (especially in elderly, diabetics)
• Management: High protein diet (1.2-1.5 g/kg/day), monitor albumin

Hypertriglyceridaemia:

• Glucose absorption stimulates hepatic VLDL production
• Management: Consider statins, icodextrin use

Pros and Cons Summary

Advantages:

• Home-based therapy (independence, flexibility)
• Continuous gentle clearance (better haemodynamic stability, no "washout")
• Preservation of residual renal function (compared to HD)
• No needles, no vascular access complications
• Less strict dietary restrictions (continuous removal allows more dietary freedom)
• Easier travel (supplies can be shipped)

Disadvantages:

• Daily patient responsibility (technique, aseptic discipline)
• Risk of peritonitis (leading cause of technique failure)
• Abdominal catheter (body image concerns)
• Storage space needed for supplies
• Contraindications: Previous extensive abdominal surgery, diverticulitis, inflammatory bowel disease (relative)

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5. Modality 3: Kidney Transplantation

Overview and Outcomes

Kidney transplantation is the definitive treatment for ESRD, offering:

• Superior survival: 50% reduction in mortality vs remaining on dialysis [5]
• Better quality of life: Freedom from dialysis, fewer dietary/fluid restrictions, improved fertility
• Cost-effectiveness: After first year, less expensive than dialysis

Donor Types and Outcomes

1. Living Donor Transplantation [5,15]

Advantages:

• Superior graft survival (half-life ~20-25 years vs 10-15 years for deceased donor)
• Shorter cold ischaemia time
• Better HLA matching (if related donor)
• Planned procedure (pre-emptive transplantation possible, avoiding dialysis entirely)

Donor Categories:

• Living related: Sibling, parent, child. 50% share one HLA haplotype with parent/child.
• Living unrelated: Spouse, friend, altruistic. "Paired exchange" programmes overcome ABO/HLA incompatibility.

Donor Evaluation:

• GFR > 80 mL/min (donor must have adequate renal reserve)
• Imaging (CT/MRI angiography): Assess anatomy, exclude renal artery abnormalities, identify which kidney to remove (usually leave kidney with better vasculature)
• Exclude: Diabetes, hypertension, proteinuria, significant comorbidities
• Psychosocial assessment: Ensure voluntary donation, no coercion

Donor Outcomes:

• Peri-operative mortality: less than 0.03% (safer than many elective surgeries)
• Long-term: No significant reduction in life expectancy in carefully selected donors
• Slight increase in ESRD risk (0.5% vs 0.15% in general population), but absolute risk remains low

2. Deceased Donor Transplantation [5,15]

Donation After Brain Death (DBD):

• Brainstem death confirmed by established criteria
• Cardiac function maintained on ICU until organ retrieval
• Better outcomes than DCD (no warm ischaemia)

Donation After Circulatory Death (DCD):

• Withdrawal of life-sustaining treatment → circulatory arrest → mandatory 5-minute stand-off → retrieval
• "Warm ischaemia" from circulatory arrest until cold perfusion initiated
• Higher rates of delayed graft function (DGF) and primary non-function vs DBD
• Graft survival approaching DBD outcomes with modern preservation techniques

Allocation Systems:

• Complex algorithms considering: HLA matching, time on waiting list, age matching, geographical proximity, immunological risk
• UK: National Kidney Offering Scheme
• Priority for: Highly sensitised patients, paediatric recipients, well-matched recipients

Immunosuppression Protocols [16,17]

Induction Therapy (at time of transplantation):

• Basiliximab (IL-2 receptor antagonist): Monoclonal antibody, low-moderate immunological risk recipients. Lower infection/malignancy risk.
• Antithymocyte globulin (ATG): Polyclonal antibody, high immunological risk (re-transplant, highly sensitised). Greater immunosuppression but higher infection risk.
• Methylprednisolone: High-dose IV at reperfusion

Maintenance Triple Therapy (Standard):

1. Calcineurin Inhibitor (CNI):

• Tacrolimus (preferred) or Ciclosporin
• Mechanism: Inhibits IL-2 production → blocks T-cell activation
• Monitoring: Therapeutic drug monitoring (trough levels). Tacrolimus target: 5-10 ng/mL (higher in early post-transplant, lower long-term).
• Toxicity: Nephrotoxicity (vasoconstriction → chronic interstitial fibrosis), neurotoxicity (tremor, headache, PRES), diabetes (tacrolimus > ciclosporin), hypertension, gingival hypertrophy (ciclosporin), hirsutism (ciclosporin)

2. Antiproliferative Agent:

• Mycophenolate Mofetil (MMF): Blocks purine synthesis → inhibits T/B cell proliferation
• Dose: 1g twice daily (adjust for GI side effects)
• Toxicity: Diarrhoea (dose-limiting, 30-40% of patients), leucopenia, anaemia, increased infection risk
• Azathioprine: Alternative (older agent). Used if MMF not tolerated. Bone marrow suppression. Drug interaction with allopurinol (reduce azathioprine dose by 75%).

3. Corticosteroids:

• Prednisolone: 5-10 mg daily long-term (lower doses with modern CNI-based regimens)
• Mechanism: Broad immunosuppression, anti-inflammatory
• Toxicity: Weight gain, diabetes, osteoporosis, hyperlipidaemia, cosmetic effects (cushingoid, acne)
• Steroid minimisation/withdrawal protocols increasingly used

Alternative Agents:

• mTOR inhibitors (Sirolimus, Everolimus): Used if CNI-sparing desired (CNI nephrotoxicity) or malignancy concern. Toxicity: Poor wound healing, mouth ulcers, proteinuria, pneumonitis, hyperlipidaemia.

Complications of Transplantation

Early (0-3 Months):

Delayed Graft Function (DGF):

• Requirement for dialysis in first week post-transplant
• Incidence: 5-10% DBD, 30-40% DCD
• Causes: Ischaemia-reperfusion injury, donor factors, CNI toxicity
• Impact: Prolongs hospital stay, increases acute rejection risk, impairs long-term graft survival

Acute Rejection:

• Incidence: 10-20% in first year (reduced with modern immunosuppression)
• Types:
  • "T-cell mediated (acute cellular rejection): Most common. Lymphocytic infiltrate on biopsy."
  • "Antibody-mediated (acute humoral rejection): Donor-specific antibodies (DSA). C4d deposition on biopsy. Worse prognosis."
• Presentation: Rising creatinine, reduced urine output, fever, graft tenderness (often subclinical)
• Diagnosis: Biopsy (gold standard - Banff classification)
• Treatment:
  • "T-cell mediated: High-dose methylprednisolone (500mg-1g IV daily x 3 days). ATG for steroid-resistant."
  • "Antibody-mediated: Plasmapheresis + IVIG ± rituximab. Bortezomib for refractory cases. [17]"

Surgical Complications:

• Vascular thrombosis (renal artery/vein): 0.5-4%. Early graft loss. Requires urgent surgical exploration ± graft nephrectomy.
• Urine leak: Ureteric anastomosis disruption. Presents with pain, rising creatinine, perinephric collection. Management: Ureteric stent or re-anastomosis.
• Lymphocele: Lymphatic fluid collection around graft. Large collections can compress ureter/vessels. Aspiration ± sclerotherapy or surgical marsupialisation.

Infection:

• Bacterial: Urinary tract infections (most common), wound infections, pneumonia
• Viral: CMV (most significant - see below), BK virus (polyoma nephropathy), EBV (PTLD risk)
• Opportunistic: Pneumocystis jirovecii (prophylaxis: co-trimoxazole for 6-12 months)

CMV (Cytomegalovirus) - The Immunosuppressed Patient's Foe:

• Timing: Usually 1-6 months post-transplant (peak 1-3 months)
• High risk: Donor CMV+ / Recipient CMV- (D+/R-)
• Presentation: CMV syndrome (fever, malaise, leucopenia, thrombocytopenia), Tissue-invasive disease (colitis, hepatitis, pneumonitis, retinitis)
• Diagnosis: CMV PCR (viral load), tissue biopsy showing "owl's eye" inclusions
• Treatment: Valganciclovir (oral) or Ganciclovir (IV). Reduce immunosuppression.
• Prophylaxis: Valganciclovir 900mg daily for 3-6 months in high-risk patients (D+/R-) [17]

Late (> 3 Months):

Chronic Antibody-Mediated Rejection (AMR):

• Leading cause of late graft loss
• Donor-specific antibodies (DSA) → endothelial injury → transplant glomerulopathy
• Diagnosis: Biopsy (glomerular basement membrane duplication, peritubular capillary changes, C4d), DSA detection
• Treatment: Difficult. Plasmapheresis, IVIG, rituximab, bortezomib. Often progressive despite treatment.

BK Polyomavirus Nephropathy (BKVN):

• Reactivation of latent BK virus (acquired in childhood, dormant in urothelium)
• Incidence: 1-10% clinical nephropathy, 30-40% viruria
• Presents: Rising creatinine, "rejection-like" picture
• Diagnosis: BK PCR in plasma (> 10,000 copies/mL suggests nephropathy), biopsy (SV40 immunostain shows intranuclear inclusions)
• Management: Reduce immunosuppression (lower CNI, stop antiproliferative). No specific antiviral. Cidofovir, IVIG, leflunomide occasionally used but limited efficacy.
• Prognosis: 10-50% graft loss despite treatment [17]

Post-Transplant Lymphoproliferative Disorder (PTLD):

• EBV-driven B-cell proliferation (90% cases EBV+)
• Incidence: 1-2% adult recipients, 5-10% paediatric
• Risk factors: EBV-seronegative recipient, intensive immunosuppression (especially ATG)
• Presentation: Lymphadenopathy, allograft mass, extranodal involvement (GI, CNS)
• Management: Reduce immunosuppression (first-line), rituximab (anti-CD20), chemotherapy (if aggressive histology)

Malignancy:

• Overall 3-5 fold increased risk vs general population
• Skin cancer (SCC >> BCC): 50-200 fold increased risk. Sun protection, regular dermatology surveillance crucial.
• Other: Kaposi sarcoma, renal cell carcinoma (native kidneys), PTLD

Cardiovascular Disease:

• Remains leading cause of death with functioning graft (40-50%)
• Risk factors: Traditional (diabetes, HTN, dyslipidaemia) + transplant-specific (immunosuppression, CKD progression)
• Management: Aggressive cardiovascular risk factor modification. Statins, aspirin, BP control.

Chronic Allograft Dysfunction:

• Progressive decline in graft function
• Multifactorial: Chronic rejection, CNI toxicity, recurrent disease, BK virus, non-adherence, donor factors
• Management: Optimise immunosuppression, control BP, proteinuria, cardiovascular risk factors

Pregnancy Post-Transplant:

• Pregnancy achievable and generally safe if stable graft function
• Wait: 12-24 months post-transplant with stable function
• Immunosuppression: Prednisolone (safe), Azathioprine (safe), Tacrolimus/Ciclosporin (acceptable - limited placental transfer). AVOID Mycophenolate (teratogenic - switch to azathioprine pre-conception).
• Risks: Hypertension, pre-eclampsia (increased risk), graft dysfunction (usually transient), preterm delivery
• Outcomes: Generally good for mother and baby with specialist multidisciplinary care [16]

Outcomes Summary

Graft Survival:

• Living donor: 1-year 98%, 5-year 90%, 10-year 70%, half-life 20-25 years
• Deceased donor (DBD): 1-year 95%, 5-year 85%, 10-year 60%, half-life 12-15 years
• Deceased donor (DCD): 1-year 92%, 5-year 80% [5,15]

Patient Survival:

• 5-year: 90-95%
• 10-year: 80-85%
• Leading causes of death: Cardiovascular disease (40%), malignancy (20%), infection (15%)

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6. Modality 4: Continuous Renal Replacement Therapy (CRRT)

Indications and Principles

CRRT is utilized primarily in intensive care settings for haemodynamically unstable patients with acute kidney injury who cannot tolerate intermittent HD. [6,18]

Advantages over Intermittent HD in ICU:

• Better haemodynamic tolerance (slow continuous fluid removal)
• Superior volume control in volume-overloaded patients
• More gradual solute clearance (reduced dialysis disequilibrium risk)
• Ability to provide large-volume nutrition/medications without fluid overload
• Better control of uraemia in hypercatabolic states

Modalities:

• CVVH (Continuous Veno-Venous Haemofiltration): Pure convective clearance. High volumes of filtrate replaced with substitution fluid.
• CVVHD (Continuous Veno-Venous Haemodialysis): Pure diffusive clearance. Dialysate runs countercurrent to blood.
• CVVHDF (Continuous Veno-Venous Haemodiafiltration): Combination of diffusion + convection. Most commonly used.

Prescription:

• Blood flow: 150-200 mL/min (lower than conventional HD)
• Effluent dose: 20-25 mL/kg/hour (target adequate clearance). Higher doses (35-40 mL/kg/hour) do NOT improve outcomes. [6,18]
• Anticoagulation: Regional citrate preferred (lower bleeding risk vs heparin)

Complications:

• Circuit clotting (requires frequent circuit changes)
• Hypophosphataemia, hypokalaemia, hypomagnesaemia (continuous losses)
• Hypothermia (blood cooling in circuit)
• High nursing workload and cost

Outcomes:

• CRRT vs intermittent HD: No survival difference in randomized trials. Choice based on haemodynamic stability.
• Timing of RRT initiation in AKI: "Early" vs "late" strategies show NO survival benefit to early initiation. Start RRT for absolute indications (AEIOU), not purely on biochemical thresholds. [6,18]

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7. Choosing the Right Modality: Individualised Decision-Making

Modality Selection Algorithm

    ESRD/Advanced CKD (eGFR less than 15 or symptomatic)
                    ↓
        EDUCATION & SHARED DECISION-MAKING
        (Low-clearance CKD clinic, MDT)
                    ↓
    ┌───────────────┼───────────────┬──────────────┐
    │               │               │              │
TRANSPLANT      HD (Centre/     PD (Home)    CONSERVATIVE
(Pre-emptive     Home)                       MANAGEMENT
  if possible)        
    │               │               │              │
    ↓               ↓               ↓              ↓
DONOR WORKUP   FISTULA CREATION  CATHETER    PALLIATIVE/
LISTING        (6-12mo advance)   INSERTION   SUPPORTIVE
               or CATHETER        (2wk mature)   CARE

Patient-Specific Considerations

Transplantation Suitability:

• Age: Traditionally less than 65-70 years, but expanding to older physiologically fit patients
• Cardiovascular fitness: Detailed pre-transplant cardiac assessment
• Contraindications: Active malignancy (less than 2-5 years cancer-free depending on tumour), active infection, severe uncorrectable cardiac disease, non-adherence

Haemodialysis Preference:

• Unable/unwilling to perform home therapy
• Previous PD failure (peritonitis, ultrafiltration failure, EPS)
• Abdominal contraindications to PD (surgery, hernias, inflammatory bowel disease)
• Need for rapid clearance (severe uraemia, hypercatabolism)
• Preference for supervised/social environment

Peritoneal Dialysis Preference:

• Independence, home-based preference
• Haemodynamic instability poorly tolerating HD
• Vascular access challenges
• Residual renal function preservation (priority in younger patients considering future transplant)
• Need for flexibility (work, travel)
• Needle phobia

Conservative Management (Non-Dialytic):

• Elderly with significant comorbidities (limited life expectancy)
• Patient choice (informed decision)
• Supportive/palliative approach: Symptom control, dietary management, quality of life focus
• Evidence: Selected elderly, frail patients may have similar survival without dialysis, with better quality of life and dignity [2]

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8. Dialysis Adequacy and Quality Measures

KDOQI/KDIGO Guidelines Summary

Haemodialysis Adequacy: [3,12]

• Kt/V: ≥1.2 per session (single-pool), ≥1.4 preferred
• URR: ≥65%
• Frequency: Minimum 3 sessions per week. Longer/more frequent beneficial (home HD).
• Session duration: Minimum 3.5-4 hours
• Ultrafiltration rate: less than 10-13 mL/kg/hour to reduce cardiac stress

Peritoneal Dialysis Adequacy: [4,12]

• Weekly Kt/V: ≥1.7 (total from PD + residual renal function)
• Creatinine clearance: ≥50 L/week/1.73m²
• Ultrafiltration: ≥750-1000 mL/day
• Residual renal function: Monitor urine output. Preserve with ACEI/ARB, avoid nephrotoxins, volume management.

Quality Measures:

• Anaemia management: Target Hb 100-120 g/L. ESA + IV iron. Avoid Hb > 130 g/L (increased cardiovascular risk).
• Mineral-bone disease: Ca 2.1-2.5 mmol/L, PO4 less than 1.8 mmol/L, PTH 2-9x upper limit normal (CKD 5D). Phosphate binders, vitamin D analogues, calcimimetics.
• Vascular access monitoring: AVF/AVG surveillance (clinical examination, flow monitoring, access recirculation)
• Infection prevention: Catheter-related bloodstream infection rate less than 1 per 1000 catheter-days
• Transplant wait-listing: All suitable patients assessed and listed

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9. Future Directions and Innovations

Emerging Technologies

Wearable Artificial Kidney (WAK):

• Miniaturised, wearable HD device (5kg belt-worn)
• Continuous or extended (8-24 hour) daily therapy
• Early trials show feasibility; challenges remain (pump size, dialysate generation, battery life)

Implantable Bioartificial Kidney:

• Silicon nanopore membranes + renal tubule cells
• Concept: Glomerular filtration via haemofilter + tubular reabsorption/secretion via cell bioreactor
• Preclinical development; transformative potential if successful

Incremental/Flexible PD:

• Individualised PD prescription based on residual renal function
• Lower fill volumes, fewer exchanges in patients with significant RKF
• May improve PD sustainability, reduce complications

Extended-Hours and Nocturnal HD:

• 5-6 sessions per week OR 8-hour nocturnal sessions 3x weekly
• Improved biochemical control, BP, LVH regression, quality of life
• Barriers: Cost, resources, patient acceptance

Biomarkers and Precision Medicine

• Donor-Derived Cell-Free DNA (dd-cfDNA): Non-invasive rejection monitoring in transplant
• Urinary NGAL, KIM-1: AKI diagnosis and prognosis
• Pharmacogenomics: Tacrolimus metabolism (CYP3A5 genotype) → personalised dosing

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10. Red Flags and Emergency Management

Critical Presentations Requiring Urgent Action

1. Loss of Fistula Thrill/Bruit:

• Diagnosis: AVF thrombosis
• Action: URGENT vascular surgery referral within 24 hours. Thrombectomy may salvage if performed early.
• Temporary measure: Insert temporary dialysis catheter for immediate access

2. Cloudy PD Effluent + Abdominal Pain:

• Diagnosis: PD peritonitis until proven otherwise
• Action:
  • Send effluent for cell count, Gram stain, culture (BEFORE antibiotics)
  • Start empirical IP antibiotics immediately (vancomycin + ceftazidime/gentamicin)
  • Admit if systemically unwell or diagnostic uncertainty

3. Severe Hyperkalaemia (K⁺ > 6.5 mmol/L) with ECG Changes:

• ECG changes: Tall tented T-waves, broad QRS, sine wave pattern (pre-arrest)
• Immediate management:
  1. Cardiac membrane stabilisation: 10% Calcium gluconate 10-20mL IV over 2-3 minutes
  2. Shift K⁺ intracellularly: Insulin 10 units + 50mL 50% glucose IV, Salbutamol 10-20mg nebulised
  3. URGENT HD: Arrange immediate HD for definitive removal. CRRT if HD not available.
• Temporising: Calcium resonium PO/PR (slow, limited efficacy)

4. Uraemic Pericarditis:

• Presentation: Pleuritic chest pain, pericardial rub, fever
• Diagnosis: ECG (widespread ST elevation, PR depression), Echo (pericardial effusion ± tamponade)
• Management:
  • URGENT intensive dialysis (daily HD or initiate PD)
  • AVOID anticoagulation (risk of haemorrhagic tamponade)
  • Monitor for tamponade (hypotension, raised JVP, pulsus paradoxus) → urgent pericardiocentesis

5. Dialysis Disequilibrium Syndrome:

• Presentation: Headache, nausea, confusion, seizures during/after HD (first few sessions)
• Prevention: Short initial sessions (2 hours), low blood flow (150-200 mL/min), gradual increase
• Management: Stop dialysis, supportive care, mannitol (if severe cerebral oedema), anticonvulsants if seizures

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11. Patient and Layperson Explanation

What is Dialysis?

Your kidneys normally perform three crucial jobs:

1. Filter waste from your blood (like a coffee filter)
2. Remove extra water (like a water pump)
3. Balance chemicals in your blood (potassium, acid, etc.)

When kidneys fail, these jobs must be done artificially. That's what dialysis does.

The Two Types of Dialysis

Haemodialysis (The Blood Machine): Think of it like taking your blood to a car wash:

• You come to hospital 3 times a week
• Two needles go into a special vein in your arm (fistula - created surgically months in advance)
• Your blood travels through tubes to a machine
• Inside the machine, your blood flows past a special filter
• The filter lets waste pass through but keeps blood cells in
• Clean blood returns to your body
• Each session takes about 4 hours

Advantages: Supervised by nurses, social contact Disadvantages: Must come to hospital, fixed schedule, post-dialysis fatigue

Peritoneal Dialysis (The Tummy Tube): Think of using your belly lining as a filter:

• A soft tube is placed permanently in your tummy (under the skin)
• Special water (dialysate) is run into your belly
• The water sits there for 4-6 hours
• Your belly lining acts like a filter - waste passes from blood into the water
• You drain the dirty water out
• This is done 4 times daily (CAPD) OR by a machine overnight while you sleep (APD)

Advantages: Done at home, independence, gentler on your body Disadvantages: Daily responsibility, risk of infection (peritonitis)

Is a Kidney Transplant a Cure?

A transplant is the closest thing to a cure. Benefits:

• Freedom from dialysis
• Better health and energy
• Fewer diet/fluid restrictions
• Longer life (on average)

BUT it's not perfect:

• You're swapping kidney failure for another condition: needing anti-rejection medicines
• Must take immunosuppression tablets daily for life
• Risk of rejection, infections, side effects
• The transplant kidney typically lasts 10-20 years (may need another transplant or return to dialysis)

How Do I Choose?

Work with your kidney doctor to decide based on:

• Your lifestyle (work, family, travel)
• Your health (heart, blood vessels, previous surgeries)
• Your preferences (independence vs supervision)
• Possibility of transplant

Many patients try different modalities over their lifetime. There's no single "best" option - it's about what's best for you.

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12. References

Primary Sources

1. Liyanage T, et al. Worldwide access to treatment for end-stage kidney disease: a systematic review. Lancet. 2015;385(9981):1975-1982. doi:10.1016/S0140-6736(14)61601-9

2. UK Renal Registry. UK Renal Registry 23rd Annual Report. Bristol: Renal Association, 2021.

3. Daugirdas JT, Blake PG, Ing TS. Handbook of Dialysis. 5th edition. Wolters Kluwer, 2015.

4. Mehrotra R, Devuyst O, Davies SJ, Johnson DW. The Current State of Peritoneal Dialysis. J Am Soc Nephrol. 2016;27(11):3238-3252. doi:10.1681/ASN.2016010112

5. Abecassis M, Bartlett ST, Collins AJ, et al. Kidney transplantation as primary therapy for end-stage renal disease: a National Kidney Foundation/Kidney Disease Outcomes Quality Initiative conference. Clin J Am Soc Nephrol. 2008;3(2):471-480.

6. Tandukar S, Palevsky PM. Continuous Renal Replacement Therapy: Who, When, Why, and How. Chest. 2019;155(3):626-638. doi:10.1016/j.chest.2018.09.004

7. Jentzer JC, Bihorac A, Brusca SB, et al. Contemporary Management of Severe Acute Kidney Injury and Refractory Cardiorenal Syndrome: JACC Council Perspectives. J Am Coll Cardiol. 2020;76(9):1084-1101. doi:10.1016/j.jacc.2020.06.070

8. Palevsky PM. Renal replacement therapy I: indications and timing. Crit Care Clin. 2005;21(2):347-356. doi:10.1016/j.ccc.2004.12.002

9. Huber TS, Berceli SA, Scali ST, et al. Arteriovenous Fistula Maturation, Functional Patency, and Intervention Rates. JAMA Surg. 2021;156(12):1111-1118. doi:10.1001/jamasurg.2021.4527

10. Cooper BA, Branley P, Bulfone L, et al. A Randomized, Controlled Trial of Early versus Late Initiation of Dialysis (IDEAL Study). N Engl J Med. 2010;363(7):609-619. doi:10.1056/NEJMoa1000552

11. Claure-Del Granado R, Clark WR. Continuous renal replacement therapy principles. Semin Dial. 2021;34(6):398-405. doi:10.1111/sdi.12967

12. Bharati J, Jha V. Achieving dialysis adequacy: A global perspective. Semin Dial. 2020;33(6):490-498. doi:10.1111/sdi.12924

13. Allon M, Al-Balas A, Young CJ, et al. Effects of a More Selective Arteriovenous Fistula Strategy on Vascular Access Outcomes. J Am Soc Nephrol. 2023;34(9):1589-1600. doi:10.1681/ASN.0000000000000174

14. Li PK, Szeto CC, Piraino B, et al. ISPD Peritonitis Recommendations: 2016 Update on Prevention and Treatment. Perit Dial Int. 2016;36(5):481-508. doi:10.3747/pdi.2016.00078

15. Bauer AC, Franco RF, Manfro RC. Immunosuppression in Kidney Transplantation: State of the Art and Current Protocols. Curr Pharm Des. 2020;26(28):3440-3450. doi:10.2174/1381612826666200521142448

16. Aiyegbusi O, McGregor E, McManus SK, Stevens KI. Immunosuppression Therapy in Kidney Transplantation. Urol Clin North Am. 2022;49(2):345-360. doi:10.1016/j.ucl.2021.12.010

17. Abu Jawdeh BG. COVID-19 in Kidney Transplantation: Outcomes, Immunosuppression Management, and Operational Challenges. Adv Chronic Kidney Dis. 2020;27(5):383-389. doi:10.1053/j.ackd.2020.07.004

18. Teixeira JP, Hiremath S, Kabli AO, et al. Continuous Kidney Replacement Therapies: Core Curriculum 2025. Am J Kidney Dis. 2025;85(6):767-786. doi:10.1053/j.ajkd.2024.09.015

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13. Examination Focus

Common MRCP/Nephrology Exam Scenarios

1. Dialysis Indication Question:

"A 55-year-old diabetic with CKD presents with confusion. Investigations: K⁺ 7.2 mmol/L, pH 7.12, Urea 45 mmol/L. ECG shows broad QRS complexes. What is the most appropriate immediate management?"

Answer:

• Immediate: IV calcium gluconate (cardiac protection), Insulin-dextrose + salbutamol (shift K⁺ intracellularly)
• Definitive: Urgent haemodialysis (satisfies AEIOU criteria - Acidosis, Electrolytes, Uraemia)

2. PD Peritonitis Recognition:

"A 60-year-old on CAPD presents with abdominal pain and cloudy dialysate bag. What is the most likely diagnosis and management?"

Answer:

• Diagnosis: PD peritonitis
• Investigations: Effluent WCC (expect > 100/μL with > 50% neutrophils), Gram stain, culture
• Management: Empirical IP vancomycin + ceftazidime/gentamicin, await cultures

3. Fistula Examination:

"You are asked to examine an AV fistula. What features would you look for?"

Answer:

• Inspection: Scars (surgical), visible pulsation, aneurysm formation, signs of infection
• Palpation:
  • Thrill (continuous buzzing - indicates patency). Loss of thrill = thrombosis emergency
  • Temperature (warm suggests good flow)
  • Aneurysm (compressible, pulsatile)
• Auscultation: Bruit (continuous machinery murmur). High-pitched = stenosis concern
• Check distal circulation: Radial pulse, capillary refill (exclude steal syndrome)

4. Transplant Immunosuppression:

"What is the standard triple therapy for kidney transplant maintenance?"

Answer:

• Calcineurin inhibitor (Tacrolimus or Ciclosporin)
• Antiproliferative (Mycophenolate Mofetil or Azathioprine)
• Corticosteroid (Prednisolone)

5. Dialysis Adequacy:

"How is adequacy of haemodialysis assessed?"

Answer:

• Kt/V: Target ≥1.2 per session (single-pool), preferably ≥1.4
  • K = dialyzer clearance, t = time, V = volume of distribution
• Urea Reduction Ratio (URR): Target ≥65%
  • "Formula: (Pre-dialysis urea - Post-dialysis urea) / Pre-dialysis urea × 100"

Viva Voce High-Yield Topics

"Why do dialysis patients itch?"

• Uraemia (uraemic toxins)
• Hyperphosphataemia (secondary hyperparathyroidism, calcium-phosphate deposition in skin)
• Dry skin (reduced sweat gland function)
• Mast cell proliferation
• Management: Optimize dialysis adequacy, phosphate binders, emollients, antihistamines, UV phototherapy

"Explain the principles of peritoneal dialysis ultrafiltration."

• Osmotic gradient created by glucose in dialysate
• Water moves from peritoneal capillaries (low osmolality) → peritoneal cavity (high osmolality)
• Higher glucose concentration = greater osmotic force = more UF
• BUT: Glucose absorbed over time → osmotic gradient dissipates → UF decreases
• Icodextrin (glucose polymer) provides sustained UF for long dwells

"What is renal bone disease and how is it managed in dialysis?"

• Pathophysiology:
  • CKD → ↓PO₄ excretion → ↑PO₄ → ↑PTH → bone resorption
  • ↓1,25-vitamin D → ↓Ca absorption → ↑PTH
• Manifestations: Bone pain, fractures, vascular calcification
• Management:
  • "Phosphate control: Dietary restriction + phosphate binders (calcium carbonate, sevelamer, lanthanum)"
  • "Vitamin D: Active vitamin D analogues (alfacalcidol, paricalcitol)"
  • "Calcimimetics: Cinacalcet (↓PTH by activating calcium-sensing receptor)"
  • "Target: PO₄ less than 1.8 mmol/L, PTH 2-9× upper limit normal (CKD 5D)"

"Why is transplantation superior to dialysis?"

• Survival: 50% mortality reduction vs remaining on dialysis
• Quality of life: Freedom from dialysis, fewer restrictions, better energy, sexual function, fertility
• Cost: Less expensive than dialysis after first year
• Complete replacement: Replaces endocrine functions (EPO, vitamin D, acid handling) that dialysis doesn't

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists and current local guidelines.