What are the differences between peritoneal (peritoneal dialysis) and hemodialysis (hemodialysis), including pros and cons for each?

Peritoneal Dialysis vs Hemodialysis: Key Differences and Clinical Selection

Both peritoneal dialysis (PD) and hemodialysis (HD) provide similar long-term survival outcomes in patients eligible for both modalities, but PD offers greater patient autonomy, lower costs, and may provide a survival advantage in the first 1.5-2 years of dialysis, particularly in younger patients and those with residual kidney function. 1, 2, 3

Fundamental Mechanistic Differences

Peritoneal Dialysis

• Uses the peritoneum as a natural semipermeable membrane with blood flow from peritoneal microcirculation, eliminating the need for an extracorporeal circuit 4
• Removes solutes through diffusion (primary mechanism for small molecules) and convection (solvent drag during ultrafiltration) 4
• Achieves only 10-20% of normal kidney clearance for urea and creatinine, with even lower clearance for higher molecular weight solutes 4
• Continuous 24-hour treatment maximizes middle molecule clearance 4

Hemodialysis

• Requires vascular access and extracorporeal blood circuit with artificial membrane 1
• Typically performed 3 times weekly in-center, though home HD options exist 1
• Provides intermittent but more intensive solute clearance per session 1

Survival Outcomes: The Critical Timeline

The survival advantage of PD is time-dependent and changes predictably over the dialysis course. 2, 5

• First 3 months: PD shows lower mortality risk compared to in-center HD 2
• First 1.5-2 years: PD survival advantage continues, especially in non-diabetic and younger diabetic patients 2, 5
• Beyond 2 years: Mortality risk with PD equals or exceeds HD, depending on patient factors 2
• Among patients eligible for both modalities: No significant survival difference at any time point 3

Critical caveat: The apparent early PD survival advantage in population studies may reflect selection bias rather than true modality effect, as healthier patients often choose PD 6, 3

Advantages of Peritoneal Dialysis

Patient-Centered Benefits

• Greater autonomy and treatment satisfaction compared to in-center HD 1
• Home-based therapy allows flexibility in scheduling and lifestyle 1, 7
• Preservation of residual kidney function longer than HD 7
• Lower treatment costs to healthcare system 1, 2, 7

Clinical Benefits

• Better preservation of residual renal function, particularly important early in dialysis 7
• Continuous solute and fluid removal provides more stable hemodynamics 4
• No need for vascular access, avoiding catheter-related bloodstream infections 2

Disadvantages of Peritoneal Dialysis

Infection Risks

• Peritonitis remains the primary complication, with unacceptably frequent episodes requiring modality switch 1
• Diverticulitis during PD often results in peritonitis 1
• Abdominal or chest wall infections can contaminate catheter exit site and peritoneal cavity 8

Nutritional Concerns

• Continuous protein loss through peritoneum can contribute to malnutrition 1, 4
• Excessive protein losses occur in high transporters, active nephrosis, or frequent peritonitis 1
• Increased caloric absorption from glucose-based dialysate may worsen obesity 1

Technical Limitations

• High technique failure rate persists despite reduced peritonitis rates 2
• Inadequate ultrafiltration in high transporters may require burdensome short-dwell regimens 1
• Low transporters in large patients may have inadequate peritoneal clearance 1
• Mechanical problems (catheter malposition, hernias, leaks) can necessitate modality switch 1

Metabolic Issues

• Unmanageably severe hypertriglyceridemia from dextrose load may increase cardiovascular risk 1

Advantages of Hemodialysis

• More efficient solute clearance per treatment session 1
• No continuous protein losses 4
• Suitable for patients with peritoneal membrane failure or extensive abdominal adhesions 8
• Direct supervision by healthcare professionals during treatment 1
• Better option for patients unable to perform self-care or lacking suitable care-partner 8

Disadvantages of Hemodialysis

• Vascular access complications, particularly catheter-related bloodstream infections 2
• Requires travel to dialysis center 3 times weekly (for in-center HD) 1
• Less patient autonomy and lifestyle flexibility 1
• Intermittent treatment causes hemodynamic instability in some patients 4
• Higher costs to healthcare system 1, 2, 7
• Faster loss of residual kidney function 7

Absolute Contraindications to Peritoneal Dialysis

PD should not be offered when: 8

• Documented loss of peritoneal function or extensive abdominal adhesions limiting dialysate flow 8
• Patient physically or mentally unable to perform PD without suitable assistant 8
• Uncorrectable mechanical defects (irreparable hernias, omphalocele, gastroschisis, diaphragmatic hernia, bladder exstrophy) 8

Relative Contraindications to Peritoneal Dialysis

Consider HD instead when: 1, 8

• Recent intra-abdominal foreign bodies (require 4-month waiting period after vascular prostheses or ventriculoperitoneal shunt) 8
• Morbid obesity creating catheter placement problems or risk of further weight gain 1, 8
• Severe malnutrition with compromised wound healing 1, 8
• Frequent diverticulitis episodes 1, 8
• Inflammatory or ischemic bowel disease 8
• Body size extremes (too small for prescribed volumes or too large for adequate dialysis) 8

Mandatory Indications for Switching from PD to HD

Transfer from PD to HD is required when: 1

• Consistent failure to achieve target Kt/Vurea and creatinine clearance despite optimal prescription 1
• Inadequate ultrafiltration or solute transport unresponsive to prescription adjustments 1
• Unacceptably frequent peritonitis or PD-related complications 1
• Irreparable technical/mechanical catheter problems 1
• Severe malnutrition resistant to aggressive management 1
• Unmanageably severe hypertriglyceridemia 1

Clinical Decision Algorithm

For incident dialysis patients with residual kidney function and no contraindications:

• Start with PD to maximize early survival advantage, preserve residual function, and provide lifestyle flexibility 2, 5, 7
• Plan for "healthy start" integrated care approach with timely transfer to HD when complications arise 5

For elderly or frail patients:

• Consider PD with home nursing support to enable home-based therapy 7
• Evaluate care-partner availability and patient's physical/cognitive ability 8

For patients with severe comorbidities or limited life expectancy:

• Either modality appropriate based on patient preference, as survival outcomes are similar 3
• Prioritize quality of life and treatment satisfaction in decision-making 1

For patients with contraindications to PD:

• HD is the appropriate choice when absolute contraindications exist 8
• Relative contraindications require individualized risk-benefit assessment 8

Common Pitfalls to Avoid

• Failing to provide high-quality pre-dialysis education about both modalities leads to physician bias determining modality rather than informed patient choice 1, 2
• Keeping patients on failing PD too long when clear indications for HD transfer exist increases morbidity and mortality 1
• Assuming PD survival advantage persists indefinitely when evidence shows it diminishes after 1.5-2 years 2
• Not planning vascular access early in PD patients who will eventually need HD 1
• Ignoring protein losses and malnutrition in PD patients, which increases mortality risk 1, 4