{"id":2737,"date":"2020-03-18T20:09:53","date_gmt":"2020-03-19T01:09:53","guid":{"rendered":"https:\/\/ami.advancedrenaleducation.com\/wparep\/?post_type=article&p=962"},"modified":"2025-05-09T15:25:55","modified_gmt":"2025-05-09T20:25:55","slug":"hemodialfiltration","status":"publish","type":"article","link":"https:\/\/ami.advancedrenaleducation.com\/wparep\/asiapacific\/article\/hemodialfiltration\/","title":{"rendered":"Hemodiafiltration"},"content":{"rendered":"

Hemodiafiltration<\/h3>\n

It is a logical step to combine the respective advantages of both procedures by doing HD and HF in parallel. This procedure is called hemodiafiltration (HDF) and probably originated from work done in the late 70\u2019s by Leber et al. in Giessen, Germany1<\/sup>.<\/i><\/p>\n

The figure outlines the respective characteristics of this procedure. In terms of solute removal HDF certainly is one of the most efficient ways to treat the blood of uremic patients.<\/p>\n

\"\"Principle:<\/h4>\n

–\u00a0 Combination <\/em>of diffusive and convective\u00a0solute transport (HD + HF = HDF<\/em>)<\/p>\n

–\u00a0 Volume substitution (pre or post filter) plus<\/em> dialysate required<\/p>\n

Selectivity:<\/h4>\n

–\u00a0 Low<\/p>\n

Efficacy:<\/h4>\n

–\u00a0 Improved for solutes (small proteins, mediators, etc.)<\/p>\n

–\u00a0 High for small molecular weight<\/em> substances (urea, creatinine, electrolytes, buffer base)<\/p>\n

Over the years there have been many publications showing the effect of HDF in comparison to HD and HF, which mainly confirmed what was initially shown2<\/sup> – HDF really combines the solute removal capabilities of both HD and HF.<\/p>\n

Clearance Comparison between HD, HF and HDF<\/strong><\/p>\n

\"\"<\/a><\/p>\n

The introduction of HDF brought up the question as to which mode of dilution (pre or post filter) was to be preferred. The problem can be investigated and answered by theoretical considerations and in-vitro experiments as done by Ahrenholz et al.3<\/sup>\u00a0 While this study specifically refers to online HDF, considerations regarding the efficacy are valid for conventional as well as for online HDF.<\/p>\n

As expected, small MW clearances are slightly reduced in pre-dilution mode due to the decreased concentration gradients across the membrane, whereas middle and higher MW clearances increase with increasing filtrate or substitution fluid flow. In the setup described here, inulin clearance can be doubled compared to pure HD.\u00a0 In-vitro experiments nicely follow theory in this case.<\/p>\n

HDF efficacy: pre-dilution (based on reference 3):<\/strong><\/p>\n

\"\"<\/p>\n

In the post-dilution mode, small MW efficacy is slightly increased (there is some convective transport for small MW solutes as well) but inulin clearances may reach the three-fold level of HD at the respective filtrate flow level. Taking into consideration that the same range of filtrate flow was used in pre- and in post-dilution modes, one can conclude that post-dilution is the best compromise between solute removal and substitution fluid consumption. Whenever possible, post-dilution should be the modality of choice. As indicated before, matching the small MW performance of post-dilution in a pre-dilution setup is possible but requires larger exchange volumes.<\/p>\n

HDF efficacy: post-dilution (based on reference 3):<\/strong><\/p>\n

\"\"<\/p>\n

In making a decision on whether to use pre- or post-dilution modes for HDF, the following should be considered:<\/p>\n