What is the importance of a night dwell in the initial prescription of Peritoneal Dialysis (PD)?

The Importance of Night Dwell in Initial Peritoneal Dialysis Prescription

Night dwells are essential in the initial peritoneal dialysis prescription as they optimize middle-molecule clearance, maximize solute removal, and improve volume control, which directly impacts patient mortality and morbidity outcomes. 1

Rationale for Including Night Dwell in Initial PD Prescription

Optimizing Clearance

• Night dwells (long-duration dwells) are critical for middle-molecule clearance, which is time-dependent rather than volume-dependent 1
• For patients with minimal residual kidney function (RKF), the PD prescription should include dwells for the majority of the 24-hour day, even if small-molecule clearance targets are met without the longer dwell 1
• Middle-molecule clearance may contribute to improved clinical outcomes, though evidence is not definitive 1

Volume Control Benefits

• The overnight dwell in CAPD and daytime dwell in APD are crucial for:
  • Maximizing solute clearance
  • Optimizing ultrafiltration volume 1
  • Improving blood pressure control
  • Reducing cardiovascular complications

Initial Prescription Recommendations

For patients with estimated GFR < 2 mL/min:

• CAPD: 2.0-3.0 L exchanges based on BSA 1
• CCPD: 2.0-3.0 L overnight (9 hours) plus 2.0-3.0 L daytime dwell 1

For patients with estimated GFR ≥ 2 mL/min:

• CAPD: 2.5-3.0 L exchanges based on BSA 1
• CCPD: 2.5-3.0 L overnight (9-10 hours) plus 2.0-3.0 L daytime dwell 1

Practical Considerations for Night Dwell Implementation

Dwell Volume Optimization

• Increase exchange volume before increasing exchange frequency to optimize clearance and minimize cost 1
• Start with increasing supine exchange volumes (night dwell) as this position has lowest intra-abdominal pressure 1
• For children, use BSA-normalized volumes (at least 1,100 mL/m²) 1

Ultrafiltration Management

• Monitor drain volumes from overnight dwells monthly 1
• For hypertensive or volume-overloaded patients, ensure ultrafiltration is not negative (no absorption) for any exchange 1
• Use the lowest possible dialysate dextrose concentration to achieve desired volume status 1

Special Considerations

Transport Status Impact

• High transporters benefit from shorter dwells during cycler therapy but still need a long dwell (day or night) with icodextrin to prevent fluid reabsorption 2, 3
• Low-average transporters benefit from longer dwells for adequate solute removal 4

Residual Kidney Function Considerations

• With significant RKF, middle-molecule clearance is less concerning as RKF contributes substantially 1
• For patients with RKF, diuretics may be preferred over increasing dialysate dextrose concentration 1, 5

Pitfalls to Avoid

• Dry day APD without day dwell: Compromises middle-molecule clearance in patients with minimal residual function 1
• Excessive dwell volumes: May increase intraperitoneal pressure causing discomfort and reduced ultrafiltration 6
• Ignoring patient lifestyle: Poor adherence occurs with demanding prescriptions; balance medical requirements with quality of life considerations 1

Algorithm for Night Dwell Implementation

1. Assess residual kidney function (RKF)
2. Determine peritoneal membrane transport characteristics
3. Select appropriate modality (CAPD vs APD) based on patient preference and clinical factors
4. For CAPD: Include overnight dwell with optimized volume based on BSA
5. For APD: Include daytime dwell to ensure 24-hour coverage
6. Monitor ultrafiltration and adjust prescription as needed

Night dwells are a fundamental component of the initial PD prescription that significantly impacts clinical outcomes by optimizing clearance and volume control.