FILTER MODULE OF AN EXTRACORPOREAL BLOOD TREATMENT MACHINE

Abstract

A filter module of an extracorporeal blood treatment machine with a filter casing in which a hollow fiber bundle is attached whose hollow fibers comprise a hollow fibre wall made of a semi-permeable membrane, and whereby in their longitudinal extension the hollow fibers comprise a number of changes in their diameter. An amplitude of 0.1 to 1 mm is achieved for the exterior diameter of the respective hollow fiber starting from the hollow fiber's axis, whereby the periodicity provided in the axial direction of the hollow fiber is within a range of 1 to 10 cm and on the inside of the filter casing at least one radial constriction is configured or provided by which the fiber bundle is locally constricted.

Claims

1-5. (canceled)

6. Filter module of an extracorporeal blood treatment machine, the filter module comprising: a filter casing; a hollow fiber bundle within the filter casing, wherein each fiber of a plurality of fibers within the hollow fiber bundle comprises a fiber wall made of a semi-permeable membrane and exhibits a number of exterior diameter changes having a periodicity between 1 and 10 cm in a longitudinal direction of the hollow fiber, the exterior diameter changes having an amplitude of 0.1 to 1 mm from a longitudinal axis of the hollow fiber; and at least one radial constriction on the inside of the filter casing that locally constricts the hollow fiber bundle.

7. The filter module according to claim 6, wherein the exterior diameter changes occur periodically in the longitudinal direction of each hollow fiber, thereby giving rise to alternating radial expansions and radial constrictions along the hollow fiber.

8. The filter module according to claim 6, wherein the thickness of the hollow fiber wall in the longitudinal direction is essentially constant, so that the interior diameter of the hollow fiber changes subject to the exterior diameter changes of the hollow fiber.

9. The filter module according to claim 7, wherein the exterior diameter changes in the longitudinal direction of the hollow fiber are applied on a continuous basis.

10. The filter module according to claim 9, wherein the exterior diameter changes in the longitudinal direction are rounded.

11. The filter module according to claim 7, wherein the transition from constrictions to subsequent expansions is configured in such a way that a fluid flow inside the hollow fiber is swirled at a known fluid viscosity and at a predefined flow speed.

12. The filter module according to claim 6, wherein the extracorporeal blood treatment machine is a dialysis machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] FIG. 1 shows a filter module, preferably a dialyzer, according to aspects of the invention, which in the present case is adapted for use in a blood treatment machine, preferably a dialysis machine,

[0024] FIG. 2 shows a longitudinal section of a hollow fiber according to a preferred embodiment of the present invention and

[0025] FIG. 3 shows a longitudinal section of a hollow fiber according to the state of the art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIG. 1 is shows a filter module 1 in schematic form. The latter therefore has a preferably cylindrical filter casing 2 whose axial ends are closed with a casing cover (not shown in more detail here because it is sufficiently familiar from the state of the art). Along the filter casing 2 on the inside there are a number of axially spaced radial protrusions 4 (only one protrusion is shown as an example), by which the interior cross-section of the filter casing 2 is locally diminished.

[0027] A bundle 6 of hollow fibers 8 is inserted in the filter casing 2, whereby a total flow lumen is formed inside the hollow fibers 8 and a total flow lumen is formed outside the hollow fibers 8 inside the filter casing 2. The two total flow lumens can be connected separately from one another via input and outlet connections (not shown in any further detail because they are sufficiently familiar from the state of the art) in the filter casing 2 and/or in the casing covers to a blood treatment machine such as a dialysis machine and to the blood circulation of a patient, in such a way that, according to the counter-current principle, blood can be directed through the hollow fibers 8 and rinsing fluid can be directed through the filter casing 2 outside the hollow fibers 8.

[0028] The radially inwardly projecting protrusions 4 have the effect of causing a local constriction of the hollow fiber bundle 6 in each case, whereby in these constricted areas the overall flow cross-section outside the hollow fibers 8 is diminished, forming a kind of flow obstacle with a higher flow resistance. This serves to ensure that a rinsing fluid on the axial inlet side of the filter module 1 evenly fills the entire flow lumen outside the hollow fibers 8.

[0029] As can be further seen from FIG. 1, the hollow fibers 8 are not configured with a constant exterior cross-section along their length but exhibit at least at the hollow fiber exterior diameter (periodically) alternating radial expansions/bulges 10 and narrowings/constrictions 12, which preferably exhibit a continuous transition between each other without forming steps or edges. The hollow fibers 8 with such an exterior diameter progression are preferably positioned inside the hollow fiber bundle 6 in such a way that the bulges 10 and constrictions>12 of different hollow fibers 8 become chaotically arranged such that neighbouring hollow fibers 8 essentially only come into contact with each other at certain points along their longitudinal extension.

[0030] In reference to FIG. 2, each such hollow fiber 8 has a semi-permeable membrane wall 14 which exhibits an (essentially) constant wall thickness along its longitudinal extension so that the radial expansions 10 and constrictions 12 of the hollow fiber exterior diameter are reflected in the hollow fiber interior diameter. In this way, nozzle-like narrowings 16 are formed on the inside of the hollow fiber, by means of which the fluid flowing through the hollow fiber 8 moves at a higher speed than it does in the area of the radial bulges 10. This in turn causes a turbulence of the fluid flow on the downstream side of the radial narrowings 12, naturally assuming sufficient knowledge of the, flow conditions and the viscosity of the fluid.

[0031] Due to the alternately positioned bulges 10 and narrowings 12, neighbouring and adjacent hollow fibers 8 essentially remain at a distance and can therefore be subjected to sufficient circulation with rinsing fluid (dialysis fluid). Furthermore, this particular construction causes a flow within the hollow fiber 8 locally in the turbulent area which causes substances intended for removal to reach the semi-permeable membrane wall 14 of the hollow fiber 8 more effectively. Both effects contribute to increasing filter capacity without enlarging the filter module 1 overall, which would make it less manageable.

[0032] It is preferable for the exterior diameter of the hollow fiber 8 to have an amplitude of 0.1 to 1 mm. An advantageous periodicity in the axial direction of the hollow fiber 8 is a range of 0.1 to 10 cm.

[0033] In summary, a hollow fiber is disclosed with a hollow fiber wall made of a semi-permeable membrane, preferably for use in a filter module of a blood purification machine, whereby the hollow fiber exhibits in its longitudinal extension a number of changes at least in its exterior diameter.