OL-HDF (Online hemodiafiltration) is widely recognised as a safer, more comfortable and more efficient alternative to conventional hemodialysis.
HDF is a renal replacement therapy combining two principles – diffusion and convection. The convective process is based on the ultrafiltration of large amounts of plasma water across the membrane. This allows for the effective removal of larger solutes due to convection in addition to the diffusive transport of small molecules.
To maintain the fluid balance it is necessary to replace the additional ultrafiltration volume, ideally after the dialyser, the so-called post-dilution HDF.
Recent publications have demonstrated that a large convective volume in post-dilution mode is required in order to maximise the benefits of HDF therapy. The production of large amounts of substitution volume is no longer a challenge. Today maximising substitution volume for each patient requires a new therapeutic approach – Online Haemodiafiltration.

Online Haemodiafiltration with its numerous positive effects on dialysis-related cardiovascular risk factors is acknowledged as the most effective dialysis treatment modality, coming closer to the elimination profile of the natural kidney.
By achieving high substitution volumes, Online Haemodiafiltration therapy is credited with more effective elimination of middle molecules. It improves patient outcomes and exerts beneficial effects on the main cardiovascular risk factors:
- Serum ß2-m and phosphate level
- Inflammatory response
- Intradialytic haemodynamic stability
- Anaemia control
These factors contribute to better quality of life and improved patient survival.


The Catalonian high-volume HDF study shows a significant 30% reduction in all-cause mortality for patients with Online Haemodiafiltration. The estimated number needed to treat showed that to prevent one death per year eight patients would need to be switched from HighFlux HD to Online Haemodiafiltration.