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Technical aspects of hemodiafiltration

James Tattersall, MD, MRCP
Peter J Blankestijn, MD
Section Editor
Paul M Palevsky, MD
Deputy Editor
Alice M Sheridan, MD


Hemodiafiltration (HDF) is a form of renal replacement therapy that utilizes convective in combination with diffusive clearance, which is used in standard hemodialysis. Compared with standard hemodialysis, HDF removes more middle-molecular-weight solutes. Some, though not all, studies have suggested that HDF is associated with improved clinical outcomes, providing adequate convection volumes are achieved.

However, HDF is more complex than standard hemodialysis and places increased demands on the user and outpatient dialysis center. HDF is available in the United States but not commonly used. In Europe, Japan, and some other countries where HDF is commonly used, most clinicians use a specific type of HDF termed online HDF. In online HDF, the substitution fluid is produced by the dialysis machine, which enables large convection volumes.

This topic reviews the technical aspects of HDF. Dosing recommendations and clinical outcomes for HDF are discussed elsewhere. (See "Chronic intermittent high-volume hemodiafiltration".)


Overview — Conventional hemodialysis clears uremic toxins mostly by diffusion driven by the thermal energy of the uremic toxin molecule. Clearance of the toxin by diffusion is inversely proportional to the radius of the toxin molecule. As a result, conventional hemodialysis clears larger toxin molecules less effectively than smaller ones. Clearance of larger toxins is limited by their low rate of diffusion, even if they can easily pass through the pores in the dialyzer membrane.

In contrast, hemodiafiltration (HDF) increases the clearance of larger toxins by large-volume ultrafiltration. Ultrafiltration carries toxins through the membrane pores by fluid flow, also known as convection. As long as the toxin molecule can easily pass through the membrane pores, the rate of transfer is independent of the molecule size.

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Literature review current through: Nov 2017. | This topic last updated: Sep 25, 2017.
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  1. Tattersall JE, Ward RA, EUDIAL group. Online haemodiafiltration: definition, dose quantification and safety revisited. Nephrol Dial Transplant 2013; 28:542.
  2. Michaels AS. Operating parameters and performance criteria for hemodialyzers and other membrane-separation devices. Trans Am Soc Artif Intern Organs 1966; 12:387.
  3. Einstein A. Uber die von der molekularkinetischen Theorie der Warme geforderte Bewegung von in ruhenden Flussigkeiten suspendierten Teilchen. Ann Phys 1905; 17:549.
  4. Gotch FA, Panlilio F, Sergeyeva O, et al. Effective diffusion volume flow rates (Qe) for urea, creatinine, and inorganic phosphorous (Qeu, Qecr, QeiP) during hemodialysis. Semin Dial 2003; 16:474.
  5. Daugirdas JT, Depner TA. A nomogram approach to hemodialysis urea modeling. Am J Kidney Dis 1994; 23:33.
  6. Waniewski J, Heimbürger O, Werynski A, Lindholm B. Aqueous solute concentrations and evaluation of mass transport coefficients in peritoneal dialysis. Nephrol Dial Transplant 1992; 7:50.
  7. Weryński A. Evaluation of the impact of ultrafiltration on dialyzer clearance. Artif Organs 1979; 3:140.
  8. Schneditz D, Yang Y, Christopoulos G, Kellner J. Rate of creatinine equilibration in whole blood. Hemodial Int 2009; 13:215.
  9. Schneditz D, Platzer D, Daugirdas JT. A diffusion-adjusted regional blood flow model to predict solute kinetics during haemodialysis. Nephrol Dial Transplant 2009; 24:2218.
  10. Tattersall JE, DeTakats D, Chamney P, et al. The post-hemodialysis rebound: predicting and quantifying its effect on Kt/V. Kidney Int 1996; 50:2094.
  11. Tattersall J. Clearance of beta-2-microglobulin and middle molecules in haemodiafiltration. Contrib Nephrol 2007; 158:201.
  12. Casino FG, Pedrini LA, Santoro A, et al. A simple approach for assessing equilibrated Kt/V beta 2-M on a routine basis. Nephrol Dial Transplant 2010; 25:3038.
  13. Haas T, Hillion D, Dongradi G. Phosphate kinetics in dialysis patients. Nephrol Dial Transplant 1991; 6 Suppl 2:108.
  14. Fischbach M, Fothergill H, Zaloszyc A, Seuge L. Hemodiafiltration: the addition of convective flow to hemodialysis. Pediatr Nephrol 2012; 27:351.
  15. Pedrini LA, De Cristofaro V. On-line mixed hemodiafiltration with a feedback for ultrafiltration control: effect on middle-molecule removal. Kidney Int 2003; 64:1505.
  16. Lee K, Lee SR, Mun CH, Min BG. Pulse push/pull hemodialysis: in vitro study on new dialysis modality with higher convective efficiency. Artif Organs 2008; 32:406.
  17. Gura V, Macy AS, Beizai M, et al. Technical breakthroughs in the wearable artificial kidney (WAK). Clin J Am Soc Nephrol 2009; 4:1441.
  18. International Electrotechnical Commission. IEC 60601. Medical electrical equipment, Part 2-16, Particular requirements for basic safety and essential performance of haemodialysis, haemodiafiltration and haemofiltration equipment. 3rd Ed, 2008.