What are the differences, pros, and cons between peritoneal dialysis (PD) and hemodialysis (HD)?

Differences Between Peritoneal Dialysis and Hemodialysis

Both peritoneal dialysis (PD) and hemodialysis (HD) achieve similar clinical outcomes and survival in most patients, but they differ fundamentally in mechanism, lifestyle impact, and specific clinical advantages. 1, 2

Fundamental Mechanisms

Hemodialysis uses an artificial membrane in an extracorporeal circuit where blood is pumped through a dialyzer, typically for 4 hours three times weekly in-center, though home HD options exist. 1

Peritoneal dialysis uses the patient's own peritoneal membrane as the dialyzer, with dialysate fluid instilled into the peritoneal cavity. Solute removal occurs through the peritoneal microcirculation, and fluid is removed by creating an osmotic gradient using hypertonic glucose or icodextrin solutions. 1

Both modalities use diffusion and convection for solute removal, but PD provides continuous clearance while HD is intermittent. 1 This continuous nature of PD may be more efficient than intermittent HD clearance, which explains why PD requires lower weekly clearance targets to achieve similar outcomes. 1

Advantages of Peritoneal Dialysis

Patient-Centered Benefits

• Greater patient autonomy and treatment satisfaction compared to in-center HD 1, 2
• Home-based therapy allowing more flexibility in daily schedule 1
• Better preservation of residual kidney function (RKF), which is critical for survival and quality of life 1, 3
• Lower cost to healthcare systems compared to in-center HD 1, 4

Clinical Advantages

• Better hemodynamic stability - avoids rapid fluid and electrolyte shifts that occur with HD, making it preferable for patients with severe cardiac disease, congestive heart failure, or extensive vascular disease 1
• Better control of anemia and avoidance of acute hypokalemia that could trigger arrhythmias 1
• More physiologic biochemical control - studies show more normal levels of BUN, hemoglobin, potassium, bicarbonate, and high-density lipoproteins with PD 5
• Reduced need for vascular access - eliminates complications associated with central venous catheters or arteriovenous fistulas 4
• Lower rates of bloodstream infections - PD reduces bacteremia/bloodstream infection episodes compared to HD 3

Survival Considerations

• Survival advantage in the first 1.5-2 years of dialysis, particularly in the first 3 months 4
• Similar long-term mortality when comparing patients eligible for both modalities 6
• In RCTs specifically, PD may reduce all-cause death risk (RR 0.53,95% CI 0.32 to 0.86) 3

Advantages of Hemodialysis

Clinical Advantages

• More normal albumin, total protein, and calcium levels compared to PD 5
• No continuous protein losses - PD patients experience ongoing protein loss in dialysate, which can worsen malnutrition 1, 7
• Higher solute clearance capacity - can achieve greater clearance per session for larger patients or those with high metabolic demands 1
• Supervised medical care in a hospital/center setting, which some patients prefer 8

Practical Advantages

• Less frequent treatment sessions - typically only 3 times weekly versus daily PD exchanges 8
• No home space requirements or need for storage of supplies 8
• No risk of peritonitis - a persistent complication of PD despite improved techniques 4

Absolute Contraindications

For Peritoneal Dialysis

• Documented loss of peritoneal function or extensive abdominal adhesions limiting dialysate flow 1, 2
• Inability to perform PD due to physical or mental incapacity without a suitable assistant 1
• Uncorrectable mechanical defects - surgically irreparable hernias, omphalocele, gastroschisis, diaphragmatic hernia, bladder extrophy 1

For Hemodialysis

• Inability to establish or maintain vascular access - though this is relative as catheters remain an option 1
• Severe hemodynamic instability unresponsive to standard HD modifications 1

Relative Contraindications and Special Considerations

PD May Be Less Favorable When:

• Inflammatory or ischemic bowel disease present - increases risk of transmural contamination by enteric organisms 2, 7
• Frequent diverticulitis episodes - significantly increases peritonitis risk 2, 7
• Morbid obesity - challenges with catheter placement, wound healing, achieving adequate clearance, and risk of further weight gain from glucose absorption 2, 7
• Severe malnutrition - compromised wound healing and inability to tolerate ongoing protein losses 7
• High peritoneal transport status - may experience poor ultrafiltration and excessive protein losses 7
• Low peritoneal transport status - may have inadequate creatinine clearance, especially in larger patients 7

HD May Be Less Favorable When:

• Severe cardiovascular disease with poor hemodynamic tolerance 1
• Difficult vascular access - multiple failed access attempts or exhausted access sites 1
• Patient preference for home therapy without ability to perform or assist with home HD 1

Common Pitfalls to Avoid

• Inadequate patient education - 43.4% of HD patients in one survey were unaware PD even existed as an option, highlighting the critical need for comprehensive modality education before dialysis initiation 8
• Physician bias driving modality selection - the treating nephrologist's recommendation was the most important factor in modality choice (77.8%), which can perpetuate underutilization of PD 8
• Ignoring peritoneal transport characteristics - not considering PET results when prescribing PD leads to inadequate dialysis 2, 7
• Failing to monitor declining peritoneal membrane function - missing the window for planned transition to HD 2
• Using actual body weight for Kt/V calculations in malnourished patients - may falsely suggest adequate dialysis 2
• Not preserving residual kidney function - both modalities should prioritize RKF preservation, but this is often neglected in HD patients 1

Decision Algorithm for Modality Selection

1. Assess absolute contraindications to either modality 1, 2, 7
2. Evaluate cardiovascular status - severe cardiac disease favors PD 1
3. Consider body habitus and nutritional status - morbid obesity or severe malnutrition may favor HD 2, 7
4. Assess gastrointestinal conditions - inflammatory bowel disease or frequent diverticulitis favors HD 2, 7
5. Evaluate patient autonomy and support system - ability to perform self-care or availability of caregiver 1
6. Consider vascular access feasibility - difficult access favors PD 1
7. Assess living environment - adequate space and "clean area" for PD supplies 8
8. Incorporate patient lifestyle preferences and work schedule - after comprehensive education on both modalities 1, 8

The choice should prioritize patient autonomy and shared decision-making after high-quality education, recognizing that clinical outcomes are largely similar between modalities when patients are eligible for both. 1, 2, 6