What are the ideal Blood Flow Rate (BFR) and Dialysate Flow Rate (DFR) for a hemodialysis patient with heart failure?

Ideal Blood Flow Rate and Dialysate Flow Rate for Hemodialysis Patients with Heart Failure

Blood Flow Rate (BFR) Recommendations

For hemodialysis patients with heart failure, target a blood flow rate of 300-400 mL/min, with 400 mL/min preferred when hemodynamically tolerated, as higher BFRs maintain better blood pressure stability during dialysis. 1, 2

Rationale for BFR Selection

• A minimum BFR of 300 mL/min is required to achieve adequate dialysis dose (spKt/V ≥1.2), and failure to maintain this threshold results in underdialysis and increased morbidity 1

• Higher BFRs (400 mL/min) are associated with better hemodynamic stability compared to lower rates (200 mL/min), with systolic blood pressure averaging 4.1 mmHg higher, diastolic pressure 3.04 mmHg higher, and mean arterial pressure 3.44 mmHg higher at the higher flow rate 2

• BFR of 400 mL/min or greater can be consistently achieved with properly placed modern catheters, making 300 mL/min a conservative minimum threshold 1

• In heart failure patients specifically, maintaining adequate BFR is critical because these patients already have compromised cardiovascular compensation and cannot tolerate the extended treatment times that result from inadequate blood flow 1, 3

Critical Monitoring Considerations

• Prepump arterial pressure monitoring is essential to ensure valid blood flows, as the criterion for adequate BFR (>300 mL/min) must be qualified by prepump arterial pressure 1

• Catheter dysfunction should be suspected when BFR falls below 300 mL/min despite adequate prepump pressure, as this indicates thrombotic occlusion requiring intervention 1

Dialysate Flow Rate (DFR) Recommendations

Standard dialysate flow rate of 500-800 mL/min is appropriate for conventional thrice-weekly hemodialysis in heart failure patients, with rates typically set at 700-800 mL/min to optimize small solute clearance. 1, 4

Rationale for DFR Selection

• The FHN Daily Trial, which demonstrated improved outcomes in patients with cardiovascular disease, used mean dialysate flow rates of 747 ± 68 mL/min for frequent hemodialysis and 710 ± 106 mL/min for conventional hemodialysis 1

• Dialysate flow rates substantially slower than blood flow rate (typically 1-2 L/hour for continuous therapies) optimize diffusive clearance while maintaining hemodynamic stability 1

• Inadequate dialysate flow reduces effective clearance and contributes to underdialysis, which is particularly problematic in heart failure patients who may already have compromised volume management 4

Special Considerations for Heart Failure Patients

Ultrafiltration Rate Management (Critical for Heart Failure)

Ultrafiltration rates should be kept below 10 mL/h/kg in heart failure patients to minimize cardiovascular mortality risk, requiring longer or more frequent dialysis sessions to achieve adequate fluid removal. 1, 5

• Ultrafiltration rates >13 mL/h/kg are associated with 59% increased all-cause mortality (HR 1.59) and 71% increased cardiovascular mortality (HR 1.71) compared to rates <10 mL/h/kg 5

• In patients with congestive heart failure, even ultrafiltration rates of 10-13 mL/h/kg are significantly associated with increased mortality, whereas this intermediate range may be tolerated in patients without heart failure 5

• The risk of cardiovascular death begins to increase at ultrafiltration rates >10 mL/h/kg regardless of heart failure status, making this a critical threshold 5

Treatment Time and Frequency Modifications

Heart failure patients benefit from longer dialysis sessions (>4 hours) or more frequent treatments (>3 times weekly) to achieve lower ultrafiltration rates while maintaining adequate volume control. 1, 3

• Peritoneal dialysis or more frequent/longer hemodialysis may be better tolerated in heart failure patients due to slower ultrafiltration rates, leading to less intradialytic hypotension and better volume control 3

• Extended treatment time allows achievement of adequate fluid removal at moderate ultrafiltration rates, reducing risk of intradialytic hypotension and end-organ ischemia (heart, brain, liver, gut, kidneys) 1

Dialysate Composition Considerations

Consider higher dialysate calcium (3.0-3.5 mEq/L) and dialysate cooling in heart failure patients to improve hemodynamic stability during ultrafiltration. 3

• Higher dialysate calcium and dialysate cooling may have hemodynamic benefits in heart failure patients by improving cardiovascular compensation during fluid removal 3

• Dialysate sodium concentration remains controversial, with lower concentrations (135 mmol/L) potentially reducing interdialytic weight gain but increasing intradialytic hypotension risk 1, 6

Common Pitfalls to Avoid

• Do not accept BFR <300 mL/min as adequate without investigating and correcting the underlying cause, as this leads to systematic underdialysis 1, 4

• Avoid aggressive ultrafiltration rates (>10 mL/h/kg) in heart failure patients even if this means extending treatment time or increasing frequency, as rapid fluid removal increases cardiovascular mortality 5

• Do not rely solely on predialysis/postdialysis blood pressure measurements in heart failure patients, as these correlate poorly with interdialytic ambulatory blood pressure and volume status 1, 6

• Failing to account for dialyzability of cardiovascular medications (particularly beta-blockers like metoprolol) can result in inadequate intradialytic cardiovascular protection 6

• Do not prioritize achieving dry weight through aggressive ultrafiltration at the expense of hemodynamic stability in heart failure patients, as the narrow therapeutic window between volume overload and depletion requires careful individualization 1

Practical Implementation Algorithm

1. Start with BFR of 350-400 mL/min and monitor prepump arterial pressure and hemodynamic stability 1, 2

2. Set dialysate flow rate at 700-800 mL/min for standard high-flux dialyzers 1

3. Calculate required ultrafiltration rate based on interdialytic weight gain and target dry weight 1

4. If ultrafiltration rate exceeds 10 mL/h/kg, extend treatment time (to 4-5 hours) or increase frequency (to 4-6 times weekly) rather than accepting higher rates 5, 3

5. Monitor intradialytic blood pressure every 30 minutes and adjust ultrafiltration rate if systolic blood pressure drops >30 mmHg or mean arterial pressure falls <65 mmHg 1, 6

6. Reassess target weight gradually (0.1 kg per 10 kg body weight over 4-12 weeks) if persistent intradialytic hypotension occurs despite optimized parameters 1