What are the differences between hemodialysis and peritoneal dialysis?

Hemodialysis vs Peritoneal Dialysis: Key Differences

Both hemodialysis (HD) and peritoneal dialysis (PD) achieve similar overall survival and clinical outcomes, but PD offers superior patient autonomy, better hemodynamic stability, and a survival advantage in the first 1.5-2 years of dialysis—particularly for younger patients, non-diabetics, and those with residual kidney function—making it the preferred initial modality when no contraindications exist. 1, 2, 3

Fundamental Mechanistic Differences

Hemodialysis:

• Requires vascular access and an extracorporeal blood circuit with an artificial synthetic membrane to filter blood outside the body 3, 4
• Provides intermittent, highly efficient solute clearance during 3-4 hour sessions, typically three times weekly 1, 3
• Achieves rapid removal of solutes like urea, potassium, phosphate, and uric acid (70-100 mL/min for uric acid) 5

Peritoneal Dialysis:

• Uses the patient's own peritoneal membrane as the natural dialyzer, with dialysate fluid instilled into the peritoneal cavity 2, 5, 4
• Provides continuous, gentler solute and fluid removal through diffusion and convection over 24 hours 3, 5
• Achieves only 10-20% of normal kidney clearance for urea and creatinine, with lower efficiency for higher molecular weight solutes 5

Clinical Advantages of Peritoneal Dialysis

Survival and Residual Function:

• PD demonstrates a survival advantage in the first 1.5-2 years of dialysis, especially in non-diabetic and younger diabetic patients 3, 6
• Better preservation of residual kidney function (RKF), which is critical for survival and quality of life 2, 7

Hemodynamic and Cardiovascular Benefits:

• Superior hemodynamic stability with smaller fluid and electrolyte shifts, making it preferable for patients with severe cardiac disease, congestive heart failure, or extensive vascular disease 2, 5, 8
• More effective blood pressure control with lower systolic and diastolic pressures compared to HD 8
• Higher cardiac ejection fraction (EF) levels compared to HD 8

Lifestyle and Autonomy:

• Greater patient autonomy and treatment satisfaction with home-based therapy allowing flexibility in daily scheduling 1, 2, 3
• No need for travel to dialysis centers three times weekly 3
• No vascular access required 7

Cost-Effectiveness:

• PD is the most cost-effective dialysis modality from a societal perspective, with potential savings of 32 million EURO for Norway and 10,623 million EURO for the European Union over 5 years with increased PD utilization 9

Clinical Advantages of Hemodialysis

Efficiency and Supervision:

• More efficient solute clearance per treatment session with no continuous protein losses 3, 5
• Direct supervision by healthcare professionals during treatment, better for patients unable to perform self-care or lacking suitable care-partners 3
• Higher albumin (ALB) levels compared to PD 8

Rapid Solute Removal:

• Superior when significant rapid removal of uric acid, urea, potassium, or phosphate is required 5

Disadvantages and Complications

Peritoneal Dialysis Limitations:

• Peritonitis remains the primary complication, with unacceptably frequent episodes requiring modality switch 3, 4
• Continuous protein loss (5-15 g/24 hours) contributing to malnutrition, requiring higher dietary protein intake (1.2-1.3 g/kg/day vs 1.2 g/kg/day for HD) 5
• Amino acid losses averaging 3 g/day 5
• Lower efficiency in rapid solute and fluid removal compared to HD 5

Hemodialysis Limitations:

• Less patient autonomy with mandatory three-times-weekly center visits 3
• Intermittent treatment-related hemodynamic instability in some patients 3
• Rapid fluid and electrolyte shifts poorly tolerated by patients with severe cardiac disease 2

Absolute Contraindications

For Peritoneal Dialysis:

• Documented loss of peritoneal function or extensive abdominal adhesions limiting dialysate flow 2, 3

For Hemodialysis:

• Inability to establish or maintain vascular access (though catheters remain an option, making this relative) 2

Relative Contraindications to Peritoneal Dialysis

• Inflammatory or ischemic bowel disease 2
• Frequent diverticulitis episodes 2, 3
• Morbid obesity 2, 3
• Severe malnutrition 2, 3
• Recent intra-abdominal foreign bodies 3

Clinical Decision Algorithm

Step 1: Assess Absolute Contraindications

• Rule out documented peritoneal membrane failure or extensive adhesions for PD 2, 3
• Evaluate vascular access feasibility for HD 2

Step 2: Evaluate Cardiovascular Status

• For severe cardiac disease, congestive heart failure, or extensive vascular disease: Strongly favor PD due to superior hemodynamic stability 2, 8
• For hemodynamically stable patients: Either modality acceptable 2

Step 3: Consider Residual Kidney Function

• For incident dialysis patients with residual kidney function and no contraindications: Start with PD to maximize early survival advantage and preserve residual function 3

Step 4: Assess Body Habitus and Nutritional Status

• Morbid obesity or severe malnutrition: Consider HD 2, 3
• Normal body habitus: Either modality acceptable 2

Step 5: Evaluate Gastrointestinal Conditions

• Active inflammatory bowel disease, frequent diverticulitis, or recent abdominal surgery: Favor HD 2, 3
• No GI pathology: Either modality acceptable 2

Step 6: Patient Autonomy and Support System

• Patients desiring autonomy with adequate cognitive/physical ability or care-partner support: Favor PD 1, 3
• Elderly/frail patients: PD with home nursing support can enable home-based therapy 3
• Patients unable to perform self-care without care-partner: Favor in-center HD 3

Step 7: Shared Decision-Making

• After high-quality education, employ shared decision-making considering quality of life, life goals, and patient preferences 1, 2

Mandatory Indications for Switching from PD to HD

• Consistent failure to achieve target Kt/Vurea and creatinine clearance despite optimal prescription 3
• Recurrent peritonitis with unacceptably frequent episodes 3

Common Pitfalls to Avoid

• Provider bias: Many regions favor HD despite PD's advantages due to healthcare system policies, provider preferences, or financial incentives rather than clinical appropriateness 1
• Inadequate patient education: Failure to provide iterative, high-quality education about both modalities limits informed decision-making 1
• Ignoring residual kidney function: Not prioritizing PD in patients with RKF misses the opportunity to preserve this critical survival factor 2, 7
• Overlooking hemodynamic considerations: Placing patients with severe cardiac disease on HD when PD would provide superior hemodynamic stability 2, 8