What is the recommended dwell time for peritoneal dialysis (PD)?

Recommended Dwell Time for Peritoneal Dialysis

For optimal patient outcomes, peritoneal dialysis should include dwells for the majority of the 24-hour day to maximize middle-molecule clearance, even when small-molecule clearance targets are already met. 1

Core Dwell Time Principles by Modality

Continuous Ambulatory Peritoneal Dialysis (CAPD)

• Operates continuously 24 hours per day, 7 days per week with fluid dwelling in the peritoneal cavity at all times 2
• Overnight dwells require particular monitoring attention as these exchanges are critical for optimizing both solute clearance and ultrafiltration volume 1
• Provides continuous renal replacement therapy delivering 168 hours of dialysis per week 2

Automated Peritoneal Dialysis (APD)

• Runs 24 hours daily with nighttime cycling typically lasting 9-10 hours 2
• Approximately 85% of APD patients require one or more daytime dwells in addition to nighttime exchanges to achieve adequate clearance 2
• Daytime dwell volumes must be monitored monthly as these are essential for maintaining adequate clearance and ultrafiltration 1

Nightly Intermittent Peritoneal Dialysis (NIPD)

• Reserved only for specific populations: high/rapid transporters with significant residual kidney function 2
• Performs exchanges exclusively during nighttime hours without daytime dwells 2
• Can be considered in pediatric patients who are clinically well and whose combined prescription plus residual kidney function exceeds target clearance without evidence of hyperphosphatemia, hyperkalemia, hypervolemia, or acidosis 1

Optimizing Dwell Time Based on Treatment Goals

For Middle-Molecule Clearance (Priority Goal)

• Prescriptions should preferentially include dwells for the majority of the 24-hour day in patients with minimal residual kidney function 1
• This recommendation applies even when small-molecule clearance is above target without the longer dwell 1
• Middle-molecule clearance is time-dependent and not significantly influenced by dialysate flow rates or dwell volumes 1

For Ultrafiltration Optimization

• Short dwell times (under 4 hours) enhance ultrafiltration capacity and are indicated for managing ultrafiltration failure, which affects 3% of patients at 1 year and 31% after 6 years 3, 4
• With icodextrin, ultrafiltration does not increase significantly beyond 10 hours of dwell time (351.73 ± 250.59 mL at 10 hours versus 371.75 ± 258.25 mL at 14 hours, p=0.83) 5
• Ultrafiltration should never be negative (no fluid absorption) for any daytime or nighttime exchanges in hypertensive patients or those with volume overload 1, 4

For Small-Solute Clearance

• Increase instilled volume per exchange first (target 1,000-1,200 mL/m² BSA, maximum 1,400 mL/m²) before increasing the number of exchanges 1
• Increase supine exchange volumes first as this position has the lowest intra-abdominal pressure 1
• Short dwell times favor small solute removal like urea but may compromise middle-molecule clearance 6

Strategic Dwell Time Variation

Combining different dwell times and volumes within the same prescription improves overall dialysis efficiency 6, 7:

• Short dwells with small fill volumes promote ultrafiltration 6, 7
• Long dwells with large fill volumes promote solute removal 6, 7
• This "adapted APD" approach significantly enhances Kt/V(urea), creatinine clearance, phosphate removal, and sodium dialytic removal compared to conventional uniform dwell times 7
• Mean blood pressure was significantly lower with varied dwell times versus uniform dwells 7

Critical Monitoring Requirements

Monthly Assessment

• Review PD effluent volume records monthly with particular attention to drain volumes from overnight dwells in CAPD and daytime dwells in APD 1, 4
• Optimize drain volume during these key dwells to maximize both solute clearance and ultrafiltration 1, 4

Baseline Transport Testing

• Obtain baseline peritoneal membrane transport study 4-8 weeks after starting dialysis to guide prescription management 1
• During training, a 4-hour dwell with 2.5% dextrose can estimate transport characteristics until formal testing 1
• Repeat testing when clinically indicated, particularly if ultrafiltration failure is suspected 1

Common Pitfalls and Caveats

• Avoid relying solely on drain volume without considering D/P ratios and formal peritoneal equilibration testing for complete membrane function assessment 4
• Do not obtain transport measurements during or within one month after peritonitis resolution as this transiently alters transport characteristics 4
• Excessive use of hypertonic solutions to increase drain volumes may damage the peritoneal membrane over time 4
• Very large fill volumes with excessive intraperitoneal pressure may result in back-filtration, reducing ultrafiltration and sodium clearance 6
• Patient schedule and quality of life must be considered as nonadherence is more common with demanding prescriptions like CAPD with 5 exchanges daily 1