Difference between peritoneal dialysis and hemodialysis
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Peritoneal Dialysis vs. Hemodialysis
Both are forms of renal replacement therapy (RRT) used in end-stage kidney disease (ESKD) when GFR falls below ~10 mL/min/1.73 m² or when uremic symptoms, refractory hyperkalemia, volume overload, or acidosis are present. Neither has been shown to be clearly superior in survival outcomes by randomized trials.
1. Basic Mechanism
| Feature | Hemodialysis (HD) | Peritoneal Dialysis (PD) |
|---|---|---|
| Membrane used | Synthetic semipermeable membrane in a dialyzer | Patient's own peritoneal membrane |
| Solute removal | Diffusion down concentration gradient + ultrafiltration (convective clearance) | Diffusion + convective clearance; rate diminishes as equilibration is reached |
| Fluid removal | Ultrafiltration via the dialyzer | Osmotic gradient using dextrose in dialysate |
| Efficiency | High - large volumes of blood cleared rapidly | Lower - slower, continuous clearance |
HD mechanism (Harrison's 22E): Solute diffusion across a hollow-fiber dialyzer; urea (60 Da) clears efficiently, creatinine (113 Da) less so. Blood and dialysate flow on opposite sides of capillary membranes at very high flow rates.
PD mechanism (Harrison's 22E): 1.5-3 L of dextrose-containing dialysate is instilled into the peritoneal cavity and dwells for 2-4 hours. Metabolic byproducts move from capillaries into the peritoneal fluid. Absorption back occurs via peritoneal lymphatics and capillaries.
2. Access
| Feature | Hemodialysis | Peritoneal Dialysis |
|---|---|---|
| Type of access | Vascular (arteriovenous fistula, AV graft, or tunneled dialysis catheter) | Peritoneal catheter (Tenckhoff catheter) |
| Lead time needed | AVF requires placement 6+ months before anticipated start | PD catheter can be placed much closer to dialysis start; urgent PD is possible |
| Invasiveness | Needle cannulation of AVF/AVG at each session, or catheter | Catheter placed surgically or laparoscopically |
- Sabiston Textbook of Surgery notes that patients with exhausted vascular access options for HD should be considered for PD as an alternative, and vice versa.
3. Schedule and Setting
| Feature | Hemodialysis | Peritoneal Dialysis |
|---|---|---|
| Frequency | Typically 3x/week, 3-4 hours per session | Daily, continuous |
| Setting | In-center (most common in US, >80%) or home | Home-based |
| Continuity | Intermittent - fluid/toxin accumulation between sessions | Continuous - more physiologic |
| CAPD | N/A | 4 manual exchanges/day (~4-6 h dwell each) |
| CCPD | N/A | Automated overnight cycling machine |
4. Contraindications and Patient Selection
PD is relatively contraindicated or less ideal in:
- Prior intra-abdominal surgery (adhesions, scar tissue) - most common barrier
- Obesity
- Ileostomy or colostomy
- Prior renal transplant
- Advanced age, diabetes, heart failure (relative)
- Patients unable to perform exchanges at home independently
HD may be less suitable in:
- Patients with no viable vascular access
- Those who live far from a dialysis center (especially in developing countries)
- Patients preferring home therapy
(Sabiston Textbook of Surgery; Comprehensive Clinical Nephrology 7th Ed.)
5. Advantages and Disadvantages
| Hemodialysis | Peritoneal Dialysis | |
|---|---|---|
| Advantages | Highly efficient solute/fluid removal; medical supervision at center; no daily home burden on patient | Continuous, physiologically smoother; home-based = independence; more liberal fluid intake; better school/work attendance; no vascular access required; better quality of life scores |
| Disadvantages | Travel burden 3x/week; intradialytic hypotension; cardiovascular stress of rapid fluid shifts; vascular access complications; AV fistula can cause high-output cardiac failure | Risk of peritonitis; membrane failure over time; technique failure due to infection/social reasons; abdominal discomfort; patient/caregiver must perform daily exchanges reliably |
6. Complications
Hemodialysis complications:
- Hypotension - most common acute complication (especially in diabetics); from excessive ultrafiltration
- Muscle cramps - from rapid volume removal
- Dialyzer reactions - Type A (IgE-mediated, anaphylactoid) or Type B (complement activation, chest/back pain)
- High-output cardiac failure from AV fistula shunting
- Vascular access infections (catheters carry highest mortality risk)
Peritoneal dialysis complications:
- Peritonitis - most important; can cause membrane failure; fungal peritonitis may require conversion to HD
- Catheter tunnel infections
- Mechanical issues (catheter malposition, leaks)
- Ultrafiltration failure (membrane deterioration over years)
- Encapsulating peritoneal sclerosis (rare but serious)
(Harrison's 22E; Comprehensive Clinical Nephrology 7th Ed.)
7. Outcomes and Survival
- No large RCT has definitively shown one modality is superior in survival - the attempted NECOSAD trial had to stop due to poor recruitment.
- Retrospective/prospective nonrandomized studies show no consistent survival advantage for either modality.
- Older evidence suggested PD may be inferior in patients with coronary heart disease or CHF long-term; more recent data suggest this may not hold.
- PD is associated with superior health-related quality of life compared to in-center HD.
- Technique failure in PD (from infection or social reasons) is associated with higher short-term mortality risk.
- In infants and pediatric patients, PD is generally preferred and widely recommended.
(Comprehensive Clinical Nephrology 7th Ed.; Harrison's 22E)
8. Special Situations Favoring Each
| Situation | Preferred Modality |
|---|---|
| Residual renal function preservation | PD (may preserve residual function longer) |
| Cardiovascular instability | PD (avoids rapid fluid shifts) |
| Diabetes with autonomic neuropathy | PD may be better tolerated |
| Prior abdominal surgeries | HD preferred |
| Remote location / resource-limited setting | PD (no center needed) |
| Infants/small children | PD (standard recommendation) |
| Patients wanting independence and home therapy | PD |
| Exhausted vascular access | PD |
| Patient unable to self-administer PD | HD |
| Pregnancy | PD or intensive HD (both used; PD may have higher small-for-gestational-age rates) |
9. Key Decision Principle
The 2019 KDOQI guidelines emphasize the "ESKD Life-Plan" - a collaborative, individualized decision between patient and interdisciplinary team selecting "the right access, for the right patient, at the right time, for the right reasons." Patient preference should be the primary factor when medical contraindications are absent. Modality-neutral counseling before dialysis start increases the likelihood patients will choose and receive PD.
- Harrison's Principles of Internal Medicine 22E, p. 535-536
- Comprehensive Clinical Nephrology 7th Ed., p. 105-135
- Sabiston Textbook of Surgery, p. 3460-3464
- Brenner and Rector's The Kidney, 2-Volume Set, p. 3633-3637
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