DIALYZER INCLUDING IMPROVED INTERNAL FILTRATION AND METHOD OF MANUFACTURE THEREOF

Abstract

A dialyzer and a method of manufacture thereof, wherein the dialyzer includes a tubular dialyzer housing in the interior of which a plurality of capillaries each extending in the longitudinal direction of the dialyzer housing and being juxtaposed transversely to the longitudinal direction is arranged, with a filler having a volume-increasing property being arranged between the inner wall of the dialyzer housing and the capillaries.

Claims

1.-12. (canceled)

13. A dialyzer comprising: a tubular dialyzer housing having an interior; a plurality of capillaries arranged within the interior of the tubular dialyzer housing, each of the plurality of capillaries extending in a longitudinal direction of the tubular dialyzer housing and being juxtaposed transversely to the longitudinal direction; and a filler having a volume-increasing property arranged between an inner wall of the tubular dialyzer housing and the plurality of capillaries, wherein the filler is surrounded by a water-permeable film or the filler is a gel-type paste or a polymer foam configured to be injected into the tubular dialyzer housing.

14. The dialyzer according to claim 13, wherein the capillaries are wrapped with a film and the filler is arranged between the film and the inner wall of the tubular dialyzer housing.

15. The dialyzer according to claim 13, wherein the filler is configured such that an increase in volume of the filler does not influence the flow rate of the plurality of capillaries when the dialyzer is in use.

16. The dialyzer according to claim 13, wherein the filler is configured to swell by exposure to water.

17. The dialyzer according to claim 16, wherein the filler is a polymer configured swell by exposure to water.

18. The dialyzer according to claim 17, wherein the filler is a homopolymer or a copolymer based on at least one of acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylate, or methacrylate.

19. The dialyzer according to claim 13, wherein the filler is strip-shaped and is wound around the plurality of capillaries transverse to the longitudinal direction.

20. The dialyzer according to claim 19, wherein the strip-shaped filler extends in the longitudinal direction over the total length of the tubular dialyzer housing.

21. The dialyzer according to claim 20, wherein the polymer foam is a two-pack polymer foam.

22. A method of manufacturing a dialyzer comprising the steps of: applying a filler, which is surrounded by a water-permeable film or which is a gel-type paste, having a volume-increasing characteristic to a bundle of capillaries, introducing the bundle of capillaries including the applied filler to a dialyzer housing, and activating a volume-increasing mechanism of the applied filler to increase the volume-increasing characteristic.

23. The method according to claim 22, wherein the volume-increasing mechanism is activated by supplying a liquid.

24. A method of manufacturing a dialyzer comprising the steps of: introducing a bundle of capillaries into a dialyzer housing, and activating a volume-increasing mechanism of a foam-type filler having a volume-increasing property by injecting the filler into the dialyzer housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is best understood from the following detailed description when read in connection with the accompanying drawings. Included in the drawings are the following figures:

[0022] FIGS. 1(a), 1(b), and 1(c) show general information about known dialysis techniques,

[0023] FIG. 2 shows a fiber bundle according to a first preferred embodiment of the invention,

[0024] FIG. 3 shows a schematic longitudinal section of a dialyzer according to aspects of the invention in accordance with a first preferred embodiment of the invention in the assembling position,

[0025] FIG. 4 shows a schematic longitudinal section of the dialyzer according to aspects of the invention in accordance with the first preferred embodiment of the invention in a completely assembled position,

[0026] FIG. 5 shows a schematic longitudinal section of a dialyzer according to aspects of the invention in accordance with a second preferred embodiment of the invention in a completely assembled position,

[0027] FIG. 6 shows a schematic longitudinal section of a dialyzer according to aspects of the invention during assembly, and

[0028] FIG. 7 shows a schematic longitudinal section of a dialyzer according to aspects of the invention in accordance with a third preferred embodiment of the invention in a completely assembled position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, preferred embodiments of the present invention shall be described by the example of a high-flux dialyzer including a volume-enlarging filler.

[0030] In a first embodiment, a filler capable of swelling in the presence of water, preferably a polymer capable of swelling by water, is used. Water-swelling polymers are known, for example, from DE-A-19748631. Especially preferred are water-swelling polymers in the form of homopolymers or copolymers on the basis of (meth)acrylic acid, (meth)acrylamides and/or (meth)acrylates, wherein in the copolymer any monomers adapted to be copolymerized with the afore-mentioned monomers which do not impair the swelling capability of the copolymer can be used. Preferred comonomers are acrylic nitrile, acrylate, acrylamide, allyl compounds, vinyl acetate, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, carboxypropyl cellulose and respective salts thereof (e.g. Na salts) as well as guar galactomannanum derivatives and the like. In the dry state the diameter of the bundle thus is increased by few millimeters only, thus allowing the bundle to be easily inserted into the dialyzer. Depending on where the polymer was applied, the film may remain in the dialyzer or may be removed again. The polymer ring or strip may remain in the dialyzer. When the dialyzer is flushed before the treatment, for example, the polymer soaks with the water of the flushing solution and its volume is increased. Crosslinked polyacrylic acid absorbs 500 to 1000 times its inherent weight of water. The increased volume of the filler ring counteracts the dialysate flow and on the upstream side causes an increase in pressure and on the downstream side causes a reduction of pressure. Preferably, the volume increase is set so that the blood flow in the capillaries is not influenced. In this way, on the downstream side by far more water is pressed through the capillary wall by the vacuum formed out of the blood to the dialysate side than in a conventional dialyzer. Said lacking water can be withdrawn from the dialysate by volume control of the dialysis apparatus on the upstream side of the dialyzer and can be absorbed by the blood. In this way, high internal filtration occurs inside the dialyzer without any additional apparatus, for example for controlling and/or regulating re-infusion from outside has to be added.

[0031] In the following, the structure and the manufacture of a dialyzer according to the first embodiment will be illustrated in detail by way of FIGS. 2 to 4.

[0032] FIG. 2 shows a schematic representation of a fiber bundle including a filler strip according to the first embodiment. A strip-shaped filler 20 made from dry polymer of the afore-mentioned type is applied directly to a bundle of a plurality of capillaries 10 (fiber bundle) or to a wrapping film enclosing the fiber bundle, said dry polymer having super-adsorbing properties and thus adopting a definitely increased volume after activation.

[0033] FIG. 3 shows a schematic representation of a dialyzer including a dialyzer housing 30 and an inserted fiber bundle of the capillaries 10 and the strip-shaped filler 20 according to the first embodiment. The fiber bundle is introduced (e.g. drawn) into the dialyzer housing 30. The little expansion of the dry polymer facilitates insertion.

[0034] FIG. 4 shows a schematic representation of the dialyzer including the dialyzer housing 30 and the inserted fiber bundle of the capillaries 10 and the strip-shaped filler 20 after activation of the volume increase, for example by exposing the latter to water. When the fiber bundle is exposed to water, the polymer of the filler 20 absorbs water and swells. Thus, flow constriction of the dialysate is formed which then results in the pressure profile shown in FIG. 1(c) with reversed pressure gradient and improved back-filtration.

[0035] FIG. 5 shows a schematic representation of a dialyzer including the dialyzer housing 30 and the inserted fiber bundle of capillaries 10 having a strip-shaped filler 20 enlarged in the longitudinal direction of the dialyzer housing 30 according to a second embodiment after volume increase thereof. The width of the strip-shaped filler (polymer strip) 20 in this way may also extend over almost the total length of the dialyzer housing 30. This measure causes the packing density of the dialyzer to be increased, which allows an improvement of the performance data of the dialyzer to be increased as a whole.

[0036] In the afore-mentioned embodiments, the polymer of the filler 20 may be applied either packed in a water-permeable film or as a gel-type paste. WO 2003020824 A1, for example, discloses a suitable self-adhesive gel matrix on the basis of polyacrylic acid containing polyvinylpyrrolidone (PVP) as a crosslinking agent.

[0037] Furthermore, the kinetics of swelling can be adjusted by the polymer content and/or the particle size, for example.

[0038] Hereinafter, an alternative third embodiment having a different configuration of the filler as polymer foam is described with reference to FIGS. 6 and 7.

[0039] FIG. 6 illustrates a schematic representation of a dialyzer with the dialyzer housing 30 being opened without any end caps including inserted nozzles 40 for introducing a foam-type filler 22 according to the third embodiment.

[0040] The polymer of the foam-type filler 22 is introduced or injected into the desired area of the dialyzer housing 30 via the long nozzles 40. By the chemical reaction during hardening a gas is formed which causes the polymer to take a foam shape and thus effectuates an increase in volume. The plastic foam system may be, for example, any one of the common foam systems used in medical engineering including e.g. a two-pack polyurethane foam, a two-pack polyurethane aerosol dosing foam and/or a two-pack epoxy resin foam. Alternatively, also silicone foam systems may be used or a polymer capable of swelling according to the first two embodiments can be introduced to a foam.

[0041] FIG. 7 shows a schematic representation of the dialyzer housing 30 including the introduced foam-type filler 22 in accordance with the third embodiment after increase in volume.

[0042] Summing up, a dialyzer and a method of manufacture thereof have been described, wherein the dialyzer includes a tubular dialyzer housing in the interior of which a plurality of capillaries 10 each extending in the longitudinal direction of the dialyzer housing 30 and being juxtaposed transversely to the longitudinal direction is arranged, with a filler 20, 22 having a volume-increasing property being arranged between the inner wall of the dialyzer housing 30 and the capillaries 10.