Which patients with end-stage renal disease (ESRD) and significant comorbidities, such as diabetes, hypertension, and cardiovascular disease, benefit from online hemodiafiltration (HDF) dialysis?

Which Patients Benefit from Online Hemodiafiltration (HDF)

Patients receiving high-volume online hemodiafiltration (convective volume >23 liters per session) demonstrate reduced all-cause mortality compared to conventional low-flux hemodialysis, though standard-volume HDF shows no survival benefit. 1

Primary Indication: High Convective Volume Achievement

The critical determinant of benefit is achieving high convective volumes during treatment:

• High-volume HDF (>23L per session) associates with lower all-cause mortality even after adjusting for confounders and dialysis facility characteristics 1
• Standard-volume HDF shows no mortality benefit compared to conventional low-flux hemodialysis (hazard ratio 0.95% CI 0.75-1.20) 1
• The convective volume threshold appears essential—without achieving high volumes, HDF offers no advantage over standard hemodialysis 1

Optimal Patient Candidates

Patients with Intradialytic Hypotension (IDH)

Online HDF provides superior hemodynamic stability compared to conventional hemodialysis, making it particularly beneficial for patients experiencing recurrent IDH. 2

• HDF techniques providing high convective solute transport associate with decreased IDH incidence and improved hemodynamic stability 2
• The improved plasma refill and appropriate neurohormonal response to intravascular volume loss explain this benefit 2
• Consider HDF for patients who fail standard IDH interventions (lowering dialysate temperature, sodium modeling, dialysate calcium at 3 mEq/L) 2

Patients with Adequate Vascular Access

Arteriovenous fistulas or grafts are strongly preferred over central venous catheters for achieving the high blood flow rates necessary for effective HDF. 2

• High-volume HDF requires blood flow rates typically ≥350-400 mL/min to achieve target convective volumes 3
• Central venous catheters often cannot sustain these flow rates consistently 2
• Patients with well-functioning arteriovenous access are more likely to achieve therapeutic convective volumes 2

Patients with Target Hematocrit Levels

Current anemia correction targets create hemorheological conditions that make high filtration rates more difficult to achieve in post-dilution HDF. 3

• Higher hematocrit levels increase blood viscosity and transmembrane pressure during post-dilution HDF 3
• Pre-dilution or mixed-dilution HDF modes may be necessary to maintain high convective volumes in patients with corrected anemia 3
• The mode of substitution (post-, pre-, or mixed-dilution) should match individual patient hemorheological conditions 3

Patients Who Do NOT Benefit

Standard-Volume HDF Recipients

• Patients unable to achieve convective volumes >23L per session show no mortality benefit (hazard ratio 0.95) 1
• No reduction in cardiovascular events occurs with standard-volume HDF (hazard ratio 1.07,95% CI 0.83-1.39) 1

Patients with Central Venous Catheters

• Catheter-dependent patients typically cannot achieve the blood flow rates necessary for high-volume convective therapy 2
• The conditional recommendation for arteriovenous access over tunneled catheters in intensive hemodialysis applies equally to HDF 2

Critical Implementation Considerations

Hemorheological Optimization

Pre-dilution or mixed-dilution modes overcome limitations imposed by higher hematocrit levels while maintaining convective clearance. 3

• Post-dilution HDF offers the most efficient diffusive-convective balance but requires lower hematocrit or reduced filtration rates 3
• Pre-dilution HDF reduces transmembrane pressure and permits higher convective volumes in patients with corrected anemia 3
• Mixed-dilution modes (varying pre-post percentages) allow individualized optimization based on patient-specific hemorheological conditions 3

Volume Management Integration

Adequate ultrafiltration and sodium restriction remain fundamental—HDF does not replace proper volume management. 2, 4

• Volume overload underlies most hypertension in dialysis patients regardless of modality 2, 4
• HDF's hemodynamic advantages facilitate achieving dry weight in patients prone to IDH 2

Common Pitfalls to Avoid

• Do not prescribe standard-volume HDF expecting mortality benefit—only high convective volumes (>23L/session) demonstrate survival advantage 1
• Do not attempt HDF in patients with inadequate vascular access—central catheters typically cannot sustain the blood flow rates required for therapeutic benefit 2
• Do not use fixed post-dilution mode in all patients—hemorheological conditions (particularly hematocrit) may necessitate pre-dilution or mixed-dilution approaches 3
• Do not neglect residual kidney function preservation—the same principles for protecting RKF in conventional hemodialysis apply to HDF patients 2