What are the different types of dialysis modalities for end‑stage renal disease?

Types of Dialysis for End-Stage Renal Disease

The primary dialysis modalities for end-stage renal disease are hemodialysis (HD), peritoneal dialysis (PD), and continuous renal replacement therapy (CRRT), with HD and PD being the mainstay chronic options and CRRT reserved for critically ill patients. 1

Primary Chronic Dialysis Modalities

Hemodialysis (HD)

Intermittent hemodialysis is the most commonly used extracorporeal kidney replacement therapy modality for patients with advanced chronic kidney disease in kidney failure. 1 This modality operates through diffusion-based clearance and is typically performed three times weekly for 3-4 hours per session. 1

HD can be delivered in two settings:

• In-center hemodialysis: Performed at dialysis facilities through vascular access via arteriovenous fistula (requires months to mature), arteriovenous graft (usable within 24 hours), or central venous catheter (immediately usable but highest infection risk). 2
• Home hemodialysis: Associated with improved survival and quality of life compared to other dialysis modes, offering greater patient autonomy and treatment satisfaction. 1, 3

Peritoneal Dialysis (PD)

PD uses the patient's own peritoneal membrane as the dialyzer, with dialysate fluid instilled into the peritoneal cavity to achieve solute exchange between blood in peritoneal capillaries and dialysis fluid. 1, 4 This modality provides continuous clearance and is performed at home. 2

PD has two primary variants:

• Continuous ambulatory peritoneal dialysis (CAPD): Based on daily manual exchanges performed by the patient at home. 1
• Automated peritoneal dialysis (APD): Exchanges performed by a simplified machine, usually at home during nighttime. 1

Specialized Modalities for Critically Ill Patients

Continuous Renal Replacement Therapy (CRRT)

CRRT is the preferred modality for hemodynamically unstable patients or those with acute kidney injury requiring intensive care. 1 This therapy runs 24 hours daily and provides superior hemodynamic stability, slower solute shifts, and better tolerance of fluid removal compared to intermittent HD. 1

Prolonged Intermittent Kidney Replacement Therapy (PIKRT)

PIKRT represents "hybrid" therapy combining characteristics of intermittent and continuous kidney replacement therapy, with prolonged duration (8-12 hours) and increased frequency. 1 No clear advantage has been demonstrated for CRRT over PIKRT in critically ill patients. 1

Intermittent Hemofiltration and Hemodiafiltration

Intermittent hemofiltration can be used in hypotension-prone patients with kidney failure on chronic kidney replacement therapy, achieving clearance through convection. 1 In most cases, hemodialysis and hemofiltration are combined in the same session (hemodiafiltration). 1

Clinical Outcomes and Modality Selection

Clinical outcomes across all dialysis modalities are largely similar, but specific clinical measures may favor one modality over another. 1 The choice among available modalities is preference-sensitive, requiring consideration of quality of life, life goals, clinical characteristics, family or care-partner support, and living environment. 1

When to Choose Peritoneal Dialysis

PD should be considered for patients with:

• Severe cardiac disease or congestive heart failure requiring better hemodynamic stability, as PD avoids rapid fluid and electrolyte shifts that occur with HD. 4
• Extensive vascular disease or inability to establish vascular access. 4
• Desire for greater patient autonomy and treatment flexibility. 1
• Need for better preservation of residual kidney function, which is critical for survival and quality of life. 4

Absolute contraindications to PD include:

• Documented loss of peritoneal function or extensive abdominal adhesions limiting dialysate flow. 4

Relative contraindications to PD include:

• Inflammatory or ischemic bowel disease, frequent diverticulitis episodes, morbid obesity, or severe malnutrition. 4

When to Choose Hemodialysis

HD should be considered for patients with:

• Hemodynamic stability allowing tolerance of intermittent treatments. 1
• Contraindications to peritoneal dialysis. 4
• Need for more efficient solute and fluid removal than PD can provide. 5

When to Choose CRRT or PIKRT

CRRT or PIKRT should be initiated for:

• Hemodynamically unstable patients who cannot tolerate conventional intermittent hemodialysis. 1
• Critically ill patients with acute kidney injury requiring intensive care unit management. 1
• Patients at high risk for dialysis disequilibrium syndrome with extremely elevated blood urea nitrogen. 6

Important Clinical Considerations

Both hemodialysis and peritoneal dialysis are equally effective long-term replacement therapies for end-stage renal disease. 1 No differences in long-term mortality rates between the two modalities have been demonstrated, though some studies suggest PD survival advantage is best at the start of dialysis (first 1.5-2 years). 2, 7

Shared decision-making between patients, care-partners, and healthcare teams is essential after high-quality education about all available modality options. 1 Everyone facing dialysis should have access to home therapy options. 1