Principles and practice of hemofiltration and hemodiafiltration

Area of Science:

• Nephrology
• Renal Replacement Therapy
• Membrane Science

Background:

• Growing clinical interest in convective dialysis therapies: hemofiltration (HF) and hemodiafiltration (HDF).
• Both therapies rely on highly permeable dialysis membranes for efficient solute and fluid transport.
• Large ultrafiltration volumes are essential for convective transport in HF and HDF.

Purpose of the Study:

• To review the principles and benefits of hemofiltration and hemodiafiltration.
• To compare the solute clearance capabilities of HF and HDF across different molecular weights.
• To discuss advancements in HF, such as predilution techniques.

Main Methods:

• Review of existing literature on convective dialysis therapies.
• Analysis of solute clearance mechanisms in HF and HDF.
• Comparison of urea and beta2-microglobulin (beta2m) clearance rates.

Main Results:

• Hemodiafiltration (HDF) combines convection and diffusion, achieving maximum clearance across the molecular weight spectrum.
• Optimal HDF shows 10-15% higher urea clearance than diffusive dialysis.
• HDF can reduce beta2-microglobulin levels by up to 70%; predilution HF improves small solute clearance.

Conclusions:

• Convective therapies, particularly HDF, offer significant advantages in solute removal, especially for larger molecules.
• Advancements like predilution HF enhance small solute clearance, broadening therapeutic applications.
• Further large-scale, long-term studies are necessary to compare outcomes of HF and HDF with other dialysis modalities.