The influence of superflux dialysis on the uremic toxicity profile: a comparison with post-dilution hemodiafiltration and low flux hemodialysis

Hemodialysis with so-called low flux membranes is the most commonly used
dialysis technique. On-line hemodiafiltration is increasingly used as an
alternative treatment, because with this technique also larger uremic toxins
can be removed. On-line hemodiafiltration is however a more complicated
technique from a technical point of view, and can only be performed with
specialized dialysis modules which are not available in all dialysis centres.
With the use of very permeable (so-called superflux) membranes it might be
possible to achieve a comparable clearance of larger uremic toxins compared to
on-line hemodiafiltration. However, this has not yet been studied.
The hypothesis of the present study is that hemodialysis with superflux
membranes, and on-line hemodiafiltration are equivalent with regard to the
clearance of larger uremic toxins and will have similar effects on plasma
levels of these toxins, and are superior to low-flux hemodialysis in this
respect.

Aim of the present study is to compare the effects of low-flux hemodialysis,
post-dilution on-line hemodiafiltration, and superflux dialysis with regard to
clearance and pre-dialytic levels of larger uremic substances. Moreover, the
effects of these techniques on albumin losses and immune status will be
studied.

In this single-centre study, treatments will be compared in a randomised
cross-over design. Twenty patients will be included. After a run-in period of 1
months in which all patients are continued to be treated with low-flux
hemodialysis, patients will either be randomised to treatment with superflux
dialysis for a period of 8 weeks, followed by 8 weeks treatment with
post-dilution on-line hemodiafiltration (A-B), or to treatment with
post-dilution on-line hemodiafiltration, followed by superflux dialysis (B-A).

Hemodialysis and on-line hemodiafiltration are accepted treatments. The time
burden for the pateint is minimal, all measurements are performed during the
dialysis treatment. The estimated albumin loss during superflux dialysis and
on-line hemodialfiltration is estimated to be comparable to peritoneal dialysis
( a regular dialysis technique by which approximately 30% of the total dialysis
population is treated) Plasma albumin levels will be closely followed.
Regarding blood sampling, it is not to be expected that the withdrawal of 180
ml of blood during a period of 5 months will have negative effects on the
hemoglobin level of the patient. As with every dialysis membrane, there is a
small risk for allergic reactions with the use of cellulose triacetate
membranes. This risk is however not increased compared with other dialysis
membranes.
There are no expected benefits for the patient. Regarding group relatedness,
this study can only be performed by the specific group of patients.