Hemodialyzer: from macro-design to membrane nanostructure; the case of the FX-class of hemodialyzers.
Very few innovations have characterized the different components of the hemodialyzers in the past 20 years. Most improvements have concerned membrane biocompatibility. In this article, we focus our attention on the most recent advances in hemodialyzer components from the macro design of the unit to the nanostructure of the membrane. For this purpose, we took as an example the FX class of hemodialyzers (FMC, Bad Homburg, Germany). The studied devices were chosen as an example representing some of the most recent hemodialyzers and are well suited to describe technical innovations occurring in the field of dialyzer technology. In vitro and in vivo studies were performed to characterize hemodynamic parameters of three models (1.4-1, 8, and 2.2 m2) and to determine membrane permeability, sieving coefficients, and solute clearances. The units were characterized by a relatively high resistance of the blood and dialysate compartments, leading to an increased internal filtration if compared with similar hemodialyzers of other series. Nevertheless, the flow distribution in both compartments was homogeneous and well balanced. This effect was obtained by the improved blood and dialysate ports design, the increased packing density of the fibers and a reduction of the inner diameter of the fibers from 200 to 180 microm. At the same time, the sieving coefficients for middle-large solutes such as beta2 microglobulin and insulin were higher than those observed in standard high flux dialysers. The same effect was noted for the clearance values of these solutes. This was observed in the absence of significant albumin leakage. These results were obtained thanks to a new nano-controlled spinning technology applied to the fiber. The innermost layer of the membrane is in fact characterized by a homogeneous porosity, with increased number of pores of large dimension but a sharp cutoff of the membrane excluding albumin losses. In conclusion, new technologies and new diagnostic tools today allow for improvement in hemodialyzer design from its macro-components to its nano-structure. The application of nanotechnology to hemodialysis will probably contribute to further developments in hemodialyzer manufacturing.
Ronco
Claudio
C
Department of Nephrology, St. Bortolo Hospital, Vicenza, Italy. cronco@goldnet.it
Bowry
Sudhir Kumar
SK
Brendolan
Alessandra
A
Crepaldi
Carlo
C
Soffiati
Giuliano
G
Fortunato
Antonio
A
Bordoni
Valeria
V
Granziero
Alessandro
A
Torsello
Giuseppe
G
La Greca
Giuseppe
G
D004867:Equipment Design; D006801:Humans; D008567:Membranes, Artificial; D006435:Renal Dialysis / Q000295:instrumentation*
D008567:Membranes, Artificial