Dialysis in the Treatment of Kidney Failure¶
Chapter 323 | Part 9: Disorders of the Kidney and Urinary Tract
KEY CLINICAL POINTS¶
- ESKD is the most common indication for dialysis, with diabetes mellitus accounting for ~45% of new cases in the U.S.
- Hemodialysis (in-center or home) and peritoneal dialysis (CAPD/CCPD) are the primary modalities, with in-center hemodialysis being most common (>80% of U.S. patients).
- Dialysis adequacy is measured by urea reduction ratio (>65–70%) and Kt/V (>1.2 or 1.05).
- Peritoneal dialysis complications include peritonitis (common pathogens: Staphylococcus), metabolic disturbances, and catheter-related infections.
- Cardiovascular disease is the leading cause of mortality in ESKD patients, with dialysis-associated risks including intradialytic hypotension and fluid overload.
1. DEFINITION & OVERVIEW¶
Dialysis is a life-sustaining therapy for end-stage kidney disease (ESKD), encompassing hemodialysis (HD) and peritoneal dialysis (PD). HD uses a semipermeable membrane to remove solutes and excess fluid, while PD relies on peritoneal membrane function for solute and water clearance. Dialysis is indicated for acute kidney injury (AKI) and chronic kidney disease (CKD) progressing to ESKD.
Dialysis Access Types and Complications¶
| Access Type | Complications | Patency Rate |
|---|---|---|
| Arteriovenous Fistula (AVF) | Thrombosis, infection, steal syndrome | Highest long-term patency |
| Arteriovenous Graft (AVG) | Thrombosis, infection | Lower patency than AVF |
| Tunneled Catheter | Infection, thrombosis | Short-term use only |
Peritoneal Membrane Transport Classification¶
| Transporter Type | Characteristics | Management Implications |
|---|---|---|
| Low Transporter | Slow equilibration, high solute clearance | Fewer exchanges, longer dwell times |
| High Transporter | Rapid equilibration, poor ultrafiltration | More frequent, shorter exchanges |
| Low-Average/High-Average | Intermediate characteristics | Balanced approach |
1.1 ESKD Epidemiology¶
In the U.S., ~800,000 patients receive dialysis, with a 65% prevalence increase since 2000. Incidence is 363 per million population/year. Diabetes mellitus is the leading cause (45% of new cases), followed by hypertension (30%). ESKD is disproportionately higher in African Americans compared to white Americans.
1.2 Dialysis Modalities¶
Hemodialysis (HD) is performed in-center or at home, while peritoneal dialysis (PD) is continuous. CRRT and PIRRT/SLED are used for acute kidney injury. Transplantation is the preferred long-term therapy but remains underutilized.
2. EPIDEMIOLOGY¶
ESKD prevalence has increased 65% since 2000, driven by improved survival on dialysis. In the U.S., ~363 new cases per million population/year. Diabetes mellitus is the leading cause (45% of new cases), followed by hypertension (30%). African Americans have higher ESKD rates compared to white Americans. Mortality is highest in developing countries due to limited dialysis access.
2.1 Risk Factors¶
Diabetes mellitus, hypertension, glomerulonephritis, polycystic kidney disease, obstructive uropathy, and APOL1 gene variants. African Americans have higher incidence due to genetic and socioeconomic factors.
2.2 Demographics¶
ESKD is more common in males, older adults, and African Americans. Mortality rates are lowest in Europe and Japan but highest in developing regions due to limited dialysis access.
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Dialysis replaces kidney function by removing waste products, excess fluid, and electrolytes. Hemodialysis relies on diffusion and convection across a semipermeable membrane, while peritoneal dialysis uses ultrafiltration and diffusion through the peritoneal membrane. Dialysis adequacy depends on blood/dialysate flow rates, membrane characteristics, and solute clearance.
3.1 Hemodialysis Mechanisms¶
Solute clearance via diffusion (urea, creatinine) and convection (large molecules). Dialysate composition (Na+, K+, Ca2+, Mg2+) and blood flow rates (250–450 mL/min) determine efficiency. Sodium modeling adjusts dialysate Na+ to prevent intradialytic hypotension.
3.2 Peritoneal Dialysis Mechanisms¶
Dialysate (dextrose/icodextrin) drives ultrafiltration and solute removal. Transporters (low/high) influence solute clearance and fluid removal. Icodextrin provides prolonged ultrafiltration with minimal glucose absorption.
4. CLINICAL FEATURES¶
Uremic symptoms (fatigue, nausea), hyperkalemia, fluid overload, and metabolic acidosis. Complications include intradialytic hypotension, muscle cramps, anaphylactoid reactions, and peritonitis. Cardiovascular disease is the leading cause of mortality, with dialysis-associated risks including fluid shifts and electrolyte imbalances.
4.1 Dialysis-Related Complications¶
Intradialytic hypotension (most common), muscle cramps, anaphylactoid reactions (Type A/B), and peritonitis (cloudy dialysate, fever). Catheter-related infections (tunnel infections) are common with tunneled catheters.
4.2 Metabolic Disturbances¶
Hyperglycemia, hyperphosphatemia, hypoproteinemia, and insulin resistance. Peritoneal dialysis causes glucose absorption and weight gain, while hemodialysis may lead to fluid shifts and electrolyte imbalances.
5. DIFFERENTIAL DIAGNOSIS¶
Dialysis is indicated for ESKD, but differential diagnoses include acute kidney injury (AKI), chronic kidney disease (CKD) progression, and other causes of uremia (e.g., severe dehydration, drug toxicity). Peritonitis must be differentiated from other abdominal infections or gastrointestinal disorders.
5.1 Non-Dialysis-Related Uremia¶
Severe dehydration, gastrointestinal losses, or drug-induced nephrotoxicity may mimic ESKD. Laboratory findings (elevated BUN/creatinine) and clinical context help distinguish these from true ESKD.
6. INVESTIGATIONS & DIAGNOSIS¶
Diagnosis of ESKD is based on serum creatinine, BUN, and estimated GFR (<10 mL/min/1.73 m2). Dialysis adequacy is measured by urea reduction ratio (>65–70%) and Kt/V (>1.2 or 1.05). Peritoneal membrane transport is assessed via the peritoneal equilibrium test (PET).
6.1 Laboratory Tests¶
Serum creatinine, BUN, electrolytes, calcium, phosphate, and parathyroid hormone (PTH). Dialysate analysis (leukocyte count, glucose, protein) for peritonitis. Urea and creatinine clearance for dialysis adequacy.
6.2 Imaging and Monitoring¶
Ultrasound for vascular access assessment. Dialysis machine monitoring for fluid balance, conductivity, and pressure. Regular assessment of residual kidney function and dialysis adequacy.
7. MANAGEMENT & TREATMENT¶
Dialysis management includes access creation (AVF/AVG), dialysate composition optimization, and complication prevention. Peritoneal dialysis requires careful monitoring of glucose absorption and fluid balance. Cardiovascular risk reduction strategies (statins, ACE inhibitors) are recommended.
7.1 Dialysis Access¶
AVF/AVG are preferred for long-term hemodialysis. Catheters are temporary for acute cases. Vascular surgeons and nephrologists collaborate to optimize access patency and reduce complications.
7.2 Dialysis Adequacy¶
Target Kt/V >1.2 or urea reduction ratio >65–70%. Sodium modeling and ultrafiltration profiling prevent intradialytic hypotension. Peritoneal dialysis requires individualized exchange schedules based on transporter classification.
7.3 Complication Management¶
Intradialytic hypotension: reduce ultrafiltration rate, administer saline. Peritonitis: intraperitoneal/oral antibiotics. Catheter infections: local/parenteral antibiotics, catheter removal if needed. Cardiovascular risk: statins, ACE inhibitors, and lifestyle modifications.
8. PROGNOSIS & COMPLICATIONS¶
Cardiovascular disease is the leading cause of mortality in ESKD patients. Dialysis-associated risks include intradialytic hypotension, peritonitis, and metabolic disturbances. Long-term outcomes are improved with residual kidney function and optimized dialysis adequacy.
8.1 Cardiovascular Risks¶
ESKD patients have 10–20x higher cardiovascular mortality than the general population. Risk factors include hypertension, diabetes, and fluid overload. Dialysis-related fluid shifts and electrolyte imbalances exacerbate cardiovascular instability.
8.2 Long-Term Outcomes¶
Peritoneal dialysis patients with residual kidney function have better survival. Hybrid approaches (CCPD + daytime exchanges) improve solute clearance but increase patient burden. Cardiovascular mortality remains high despite optimal dialysis management.
9. SPECIAL CONSIDERATIONS¶
Pregnancy: dialysis is safe but requires careful monitoring of fluid balance and electrolytes. Pediatrics: peritoneal dialysis is preferred for children due to lower vascular access risks. Elderly: increased risk of hypotension and frailty; dialysis adequacy must be individualized.
9.1 Pregnancy¶
Dialysis is indicated for ESKD in pregnancy. Peritoneal dialysis is preferred to avoid maternal vascular access complications. Close monitoring of fetal growth and maternal electrolytes is required.
9.2 Pediatrics¶
Children on dialysis require smaller dialysate volumes and adjusted dialysis schedules. Peritoneal dialysis is more feasible in children due to lower vascular access risks and better growth outcomes.
10. KEY POINTS & CLINICAL PEARLS¶
- ESKD is the most common indication for dialysis, with diabetes as the leading cause. 2. Hemodialysis is most common in the U.S., while peritoneal dialysis is preferred for continuous management. 3. Dialysis adequacy is measured by urea reduction ratio and Kt/V. 4. Peritonitis is the most common complication of peritoneal dialysis. 5. Cardiovascular disease is the leading cause of mortality in ESKD patients. 6. Sodium modeling and ultrafiltration profiling prevent intradialytic hypotension. 7. Peritoneal membrane transport classification guides exchange schedules. 8. Statins and ACE inhibitors improve cardiovascular outcomes in dialysis patients.