What are the recommended dialysis flow rates for patients undergoing hemodialysis (HD) and peritoneal dialysis (PD)?

Dialysis Flow Rates: Hemodialysis and Peritoneal Dialysis

Hemodialysis Blood Flow Rate

For hemodialysis patients, target a blood flow rate of 300-400 mL/min, with 400 mL/min preferred when hemodynamically tolerated, as blood flow rates below 250 mL/min are associated with significantly increased all-cause mortality. 1, 2

• Blood flow rate below 300 mL/min indicates catheter dysfunction requiring intervention 1
• Blood flow rate below 250 mL/min increases all-cause mortality risk (hazard ratio 1.66,95% CI 1.00-2.73) compared to rates ≥250 mL/min 2
• Increasing blood flow from 200 to 250 mL/min significantly improves dialysis adequacy, with 35.7% of patients achieving URR >65% at 250 mL/min versus only 16.7% at 200 mL/min 3
• Higher blood flow rates (400 mL/min) provide better hemodynamic stability during dialysis sessions 1
• Even in patients with compromised vascular access flow (<600 mL/min), increasing blood flow rate generally increases delivered Kt/V without significant access recirculation 4

Critical Exception for Blood Flow Adjustment

• Decrease blood flow to 50-100 mL/min for 15 seconds at dialysis completion for accurate post-dialysis BUN sampling 5
• This temporary reduction clears arterial line dead space of recirculated blood before sampling 5

Hemodialysis Dialysate Flow Rate

Set dialysate flow rate at 700-800 mL/min for conventional thrice-weekly hemodialysis to optimize small solute clearance. 1, 6

• Standard dialysate flow range is 500-800 mL/min 1
• Increasing dialysate flow from 500 mL/min to 700 mL/min significantly improves Kt/V (1.41±0.23 to 1.46±0.24) and URR (68.67±5.22 to 70.11±5.13) 6
• The optimal blood-to-dialysate flow ratio is 1:2 to achieve well-balanced dialysis efficiency 7
• For blood flow of 200 mL/min, dialysate flow of 400 mL/min maintains adequate efficiency while reducing costs 7
• Dialysate flow rates of 747±68 mL/min for frequent hemodialysis and 710±106 mL/min for conventional hemodialysis were used in the FHN Daily Trial with improved cardiovascular outcomes 1

Common Pitfall to Avoid

• In Japan, dialysate flow is often set at 500 mL/min regardless of blood flow rate, which may not optimize the 1:2 ratio 7
• When blood flow is 300-400 mL/min, dialysate flow should be 600-800 mL/min to maintain the optimal ratio 7

Hemodialysis Ultrafiltration Rate

Maintain ultrafiltration rate below 10 mL/h/kg to minimize cardiovascular mortality risk, particularly in patients with heart failure. 1

• Ultrafiltration rate of 417 mL/hour (for 2.5L over 6 hours) is generally well-tolerated for most patients 1
• Excessive ultrafiltration rates increase risk of intradialytic hypotension and end-organ ischemia 1
• Extended treatment time allows adequate fluid removal at moderate ultrafiltration rates 1
• Monitor blood pressure every 30 minutes and adjust ultrafiltration if systolic blood pressure drops >30 mmHg or mean arterial pressure falls <65 mmHg 1

Peritoneal Dialysis Treatment Duration

Peritoneal dialysis operates continuously 24 hours per day, 7 days per week (168 hours weekly), with prescriptions including dwells for the majority of the 24-hour day to maximize middle-molecule clearance. 8

Continuous Ambulatory Peritoneal Dialysis (CAPD)

• CAPD operates 24/7 with fluid continuously dwelling in the peritoneal cavity 8
• Fluid remains in the peritoneal cavity throughout the entire day and night 8

Automated Peritoneal Dialysis (APD)

• APD runs 24 hours daily but concentrates exchanges during nighttime hours 8
• Cycling machine performs exchanges overnight, typically 9-10 hours per night 8
• Approximately 85% of APD patients require one or more daytime dwells in addition to nighttime cycling to achieve adequate clearance 8

Nightly Intermittent Peritoneal Dialysis (NIPD)

• NIPD performs exchanges only during nighttime hours without daytime dwells 8
• Reserved for specific populations: high/rapid transporters with significant residual kidney function, or pediatric patients who are clinically well with combined prescription plus residual function exceeding target clearance 8

Peritoneal Dialysis Dwell Time Optimization

Prescriptions should include dwells for the majority of the 24-hour day, even when small-molecule clearance targets are already met, to maximize middle-molecule clearance. 8

• Middle-molecule clearance is time-dependent and not significantly influenced by dialysate flow rates or dwell volumes 8
• Overnight dwells in CAPD and daytime dwells in APD are critical for optimizing both solute clearance and ultrafiltration 8
• Review peritoneal dialysis effluent volume records monthly with particular attention to drain volumes from these key dwells 8

Volume Optimization Strategy

• Increase instilled volume per exchange first (target 1,000-1,200 mL/m² BSA, maximum 1,400 mL/m²) before increasing number of exchanges 8
• Increase supine exchange volumes first as this position has lowest intra-abdominal pressure 8

Monitoring Requirements

Hemodialysis

• Measure delivered dose at least once monthly in all patients 1
• Increase measurement frequency when patients are non-compliant, frequent delivery problems occur, wide variability in results is observed, or prescription is modified 1
• Monitor prepump arterial pressure to ensure valid blood flows 1

Peritoneal Dialysis

• Obtain baseline peritoneal membrane transport study 4-8 weeks after starting dialysis 8
• Repeat testing when clinically indicated, particularly if ultrafiltration failure is suspected 8
• Monitor daytime dwell volumes monthly as these are essential for maintaining adequate clearance 8