What are the types of dialysis?

Types of Dialysis

There are two main types of dialysis for end-stage renal disease: hemodialysis (HD) and peritoneal dialysis (PD), with each modality having distinct subtypes based on location and delivery method. 1

Primary Dialysis Modalities

Hemodialysis (HD)

• In-center hemodialysis is performed at a dialysis facility, typically three times weekly, using an extracorporeal circuit where blood is pumped through an artificial dialyzer to remove waste products and excess fluid 2
• Home hemodialysis allows patients to perform dialysis treatments at home with appropriate training and equipment, offering greater scheduling flexibility 1
• HD requires vascular access through an arteriovenous fistula (preferred), arteriovenous graft, or central venous catheter 1

Peritoneal Dialysis (PD)

• Continuous Ambulatory Peritoneal Dialysis (CAPD) involves manual exchanges of dialysate fluid 3-4 times daily, with the patient's peritoneal membrane serving as the natural dialyzer 1, 3
• Automated Peritoneal Dialysis (APD) uses a cycler machine to perform exchanges automatically, typically overnight while the patient sleeps 1
• PD uses the peritoneal membrane as a semipermeable barrier, with dialysate instilled into the peritoneal cavity to remove uremic toxins through diffusion and convection 4, 3

Key Mechanistic Differences

Hemodialysis Characteristics

• Intermittent treatment with rapid solute and fluid removal over 3-4 hour sessions 2
• Highly efficient at removing small and middle molecules, achieving higher clearance rates than PD 5, 3
• Requires anticoagulation during treatment and produces significant hemodynamic shifts 5

Peritoneal Dialysis Characteristics

• Continuous treatment providing gentler, more physiologic solute and fluid removal 5, 4
• Better preservation of residual kidney function compared to HD 4
• Achieves only 10-20% of normal kidney clearance for substances like urea and creatinine 3
• Middle molecule clearance is maximized by continuous 24-hour dialysis without dry periods 3

Clinical Outcomes and Patient Selection

Survival Considerations

• Clinical outcomes and survival are largely similar between HD and PD in most patients 4
• PD may have a survival advantage in the first 1.5-2 years of dialysis, particularly in the first 3 months, but this advantage diminishes over time 6, 7
• In children, there appears to be little or no difference in all-cause death between HD and PD 8

When to Favor Peritoneal Dialysis

• Cardiovascular instability: PD provides superior hemodynamic stability with fewer cardiovascular fluctuations, making it preferable for patients with severe cardiac disease, congestive heart failure, or extensive vascular disease 5, 4
• Geographic barriers: Home-based PD eliminates transportation challenges for patients in remote locations 5
• Preservation of residual kidney function: PD better maintains remaining kidney function, which is critical for survival and quality of life 4
• Patient autonomy: PD offers greater treatment satisfaction and flexibility in daily scheduling 1, 4

When to Favor Hemodialysis

• Rapid solute removal needed: HD is more efficient for removing solutes and fluid, essential in conditions like tumor lysis syndrome (unless hemodynamic instability precludes it) 5
• Peritoneal contraindications present: Documented loss of peritoneal function, extensive abdominal adhesions, inflammatory or ischemic bowel disease, frequent diverticulitis, or abdominal wall infections 5, 4
• Body habitus extremes: Patients too small to tolerate prescribed dialysate volumes or too large to achieve adequate dialysis with PD 5
• Inability to perform home therapy: Lack of manual dexterity, cognitive impairment, or absence of care-partner support when needed 1

Common Pitfalls and Caveats

• Avoid premature dialysis initiation: Unless glomerular filtration rate is very low (eGFR < 6 mL/min/1.73 m²), dialysis can be delayed as long as hypervolemia is controlled and uremic symptoms are absent 2
• Recognize PD limitations: PD does not replace tubular secretive/reabsorptive or endocrine kidney functions, and causes continuous protein and nutrient losses that can contribute to malnutrition 3
• Address vascular access early for HD: Central venous catheters are associated with high infection-related mortality and morbidity; arteriovenous fistulas should be created well in advance 6
• Monitor for technique failure: PD has persistently high technique failure rates despite reduced peritonitis rates, requiring vigilant monitoring 6
• Consider cost implications: PD costs are significantly lower than in-center HD, which may influence healthcare system policies and patient access 1, 6

Shared Decision-Making Framework

• Both modalities should be presented through high-quality, iterative education involving healthcare professionals, patients, and care-partners 1
• Choice among available modalities is preference-sensitive, considering quality of life, life goals, clinical characteristics, family support, and living environment 1
• Kidney transplantation remains the preferred treatment option for eligible ESRD patients when available 5
• For patients choosing conservative management, comprehensive palliative care should be provided for symptom management 5