IMPROVED PROTECTION FILTER FOR HEMODIALYSIS LINES

The present invention relates to a protection filter for hemodialysis lines in accordance with the introduction to the main claim. A protection filter for hemodialysis lines is known to comprise a body connected to two conduits, of which a first conduit is connected to a dialysis machine and the second conduit is directed towards the patient. The body of known filters usually presents a normally discoidal central portion having opposing faces from which usually cylindrical or frusto-conical connection members project for connection to said conduits. Each connection member or coupling is provided with a through hole opening at the free end of the relative member and joined to the other hole within the central portion of the filter body. In this latter, between the two holes a filter element is present generally defined by an antibacterial, hydrophobic and hemophobic membrane - i.e. a media filter system. The purpose of this membrane is to enable air to be transferred from one conduit to the other via a filter (blocking the blood) in order to enable, via this latter, the hemodialysis treatment to be controlled while being carried out on a patient and to preserve (or protect) the dialysis machine from possible contact with the blood. This control is in fact achieved by measuring the pressure of the hemodialysis line by passage of the air passing through the filter, this air generating a pressure in the conduit directed towards the dialysis machine, this pressure being measured by known usual sensor means positioned in that conduit or in the machine. The filter element (membrane or other) hence enables air to pass while blocking blood flow towards the machine, the patient dialysis process being controlled by means of this passage.

Known filters, of any form, present a body generally produced in two or more parts welded together (for example by ultrasonic welding). For example a known filter comprises a body presenting two parts, each provided with a

generally discoidal portion, from a face of which there projects a member for coupling or connecting to a relative conduit (tube). The filter is produced by coupling together the generally discoidal portions of the two parts after inserting a filter element between them; the two coupled parts of the two portions are then welded together, to define the filter body.

This known solution therefore presents an undeniable production complexity, which reflects on the filter production costs.

Another known process for producing a protection filter for hemodialysis lines comprises firstly moulding from plastic a part of the filter body presenting the discoidal portion and the coupling member, then opening the mould to arrange the filter element on the discoidal portion and then overmoulding the second part of the filter body provided with the other discoidal portion and the relative coupling member. This method of producing the filter for hemodialysis lines results in a non-homogeneous body in which its two parts are separated and distinguishable from each other. This solution is also laborious and costly.

Moreover as the known solutions comprise a plurality of operations to be carried out on the individual components of the filter body, they inevitably lead to a non-negligible percentage of product defects , this also having to be considered in evaluating the final cost of the correctly finished product ready for sale. These defects can also be problematic if they are not identified prior to marketing the filter in that they can lead for example to blood passage through the filter and towards the dialysis machine.

An object of the present invention is to provide a protection filter for hemodialysis lines which overcomes the drawbacks of the known solutions and which represents an improvement thereon.

Another object is to provide a protection filter for hemodialysis lines of the aforestated type which is of simpler production than known filters and is hence of lower production cost then these.

A further object is to provide a filter of the aforestated type which offers considerable safety in use.

These and other objects which will be apparent to the expert of the art are attained by a protection filter for hemodialysis lines in accordance with the accompanying claims.

The present invention will be more apparent from the accompanying drawing, which is provided by way of non-limiting example and in which: Figure 1 is a partly broken-away perspective view of a first embodiment of the invention; and Figure 2 is a perspective view similar to that of Figure 1 , but of a different embodiment of the invention.

With reference to said figures, a protection filter for hemodialysis lines is indicated overall by 1 and presents a completely homogeneous one-piece body 2 with no joining lines or regions in its various parts. In the embodiments shown in the figures by way of non-limiting example, these parts comprise a substantially central discoidal portion 3 useful for "manipulating" the filter, and having two opposing flat faces 4 and 5 with coupling members 7 and 8 projecting from said faces 4, 5. These members are arranged to cooperate with conduits or tubes directed towards a patient subjected to dialysis and towards a dialysis machine.

The coupling members comprise a through hole 9, 10 respectively, opening at the free ends 7A, 8A of the corresponding member 7 and 8. The holes 9 and 10 are for example (but not necessarily) coaxial and are connected together at the discoidal portion 3 where they are separated by a filter element 12. The filter element 12 presents at least one end edge 13 incorporated into the one-piece body 2 so that it becomes securely fixed to this latter. This element can be flat (Figure 1) or of beak type with pleated or folded walls or it can extend axially within the body 2 and presents a plurality of surface pleats which

increase the transfer surface. As an alternative, the element 12 can be of hemispherical form similar to a dome or have any other form able to define a large filtering surface for equal bulk.

The discoidal portion 3 can advantageously present a raised end edge rising peripherally from one of its faces 4, 5, said edge facilitating manipulation of the filter in connecting the body 2 to at least one corresponding conduit. The body 2 of the filter 1 , produced by known plastic moulding, is of very small size. For example it has an axial height between 10 and 50 mm and a diameter between 4 and 20 mm. The portion 3 can have a diameter which depends mainly on its appearance and related to the positioning of the filter in the dialysis machine, and is between 4 and 50 mm. The body is produced by moulding in a single operation (method known as overmoulding or insert moulding) during which the members 7 and 8 and the portion 3 are formed simultaneously, said elements being overmoulded simultaneously on the filter element 12, which is hence incorporated and inserted into the body 2 of the filter !

The invention is hence of simple and rapid implementation. Being in one piece and being without joining lines between its various components (the members 7, 8 and the portion 3), it is also of reliable use in that its shape ensures lack of seepage and leakages in terms of blood and air. The body 2 of the filter 1 is produced in a single moulding operation and is hence of much lower complexity and costs than similar known solutions.

A particular embodiment of the invention has been described. However the body 2 of the filter 1 can also be of different shape than that shown in the drawings; for example, it can be completely tubular, without the generally discoidal portion 3 (with flat faces or with a raised perimetral edge), in which case the members 7 and 8 are defined by the ends of the tubular body. In another embodiment, this body can be prismatic and provided with the

members 7 and 8. In any event, whatever its shape this body is in one piece and without joining lines, it being provided with a through conduit defined by holes provided in the coupling members 7 and 8 and mutually communicating via a filter element in the body interior and with its lateral edge incorporated into said filter body.

These solutions are also to be considered as falling within the scope of the following claims.