BACKGROUND OF THE INVENTION Various means exist for supporting a filter media in a filter device for distributing a flow of biological liquid. However, none of the known means provide sufficient support to minimize localized collapse of the filter media. This is particularly true where the filter media is positioned between a filter housing and a closure member in a state of compression, and where biological liquid, such as blood . or blood product, is desired to flow through the media and filter device.

Accordingly, a need exists to provide a flow distributor in a filter device that enhances the flow of liquid, and preferably biological liquid such as blood or blood product, through the filter media and filter device. Additionally, or alternatively, a flow distributor is needed that minimizes localized collapse

of the filter media and thereby enhances the flow of liquid through the media and filter device. The flow distributors disclosed in prior art do not offer the flexibility and inventive features of the present improved flow distributor and method for use with a biological liquid filter device.

SUMMARY OF THE INVENTION According to the present invention there may be provided an improved flow distributor for use with a biological liquid filter device including a filter housing. Such a flow distributor comprises a projecting support member, and preferably a plurality of such support members, where the support member is joined with the filter housing. Further, the support member has an upper surface including a first upper section pitched downwardly in at least a first direction and a second upper section pitched downwardly in at least a second direction.

According to other features of the invention there may also be provided a method for flowing biological liquid in the filter device including a filter media and a filter housing. The method preferably comprises : supporting the filter media in contact with at least one support member, which support member is joined with the filter housing ; compressing the filter media within the filter device with a compression force ; and, distributing a portion of the compression force to the support member wherein the filter media is spaced from the filter housing by the support member and adjacent the support member a flow path is maintained through the filter media.

Other features of the invention relate to the particular type and orientation of the pitched first and second sections and the orientation of the plurality of support members relative to one another and relative to the filter housing.

DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will become more readily apparent upon reference to the following description when taken in conjunction with the accompanying drawings, which drawings illustrate preferred embodiments of the invention.

FIG. 1 is an assembled perspective view of a biological liquid filter device incorporating an improved flow distributor in accordance with the principles of the present invention.

FIG. 2 is an exploded perspective view of the filter device seen in FIG. 1, here specifically depicting the flow distributor, a closure member, a multilayered filter media and a filter housing.

FIG. 3 is a top view of the flow'distributor seen in FIG. 2.

FIG. 4 is a cross-sectional side view, taken along the line 4-4, of the flow distributor seen in FIG. 3.

FIG. 5 is a cross-sectional side view, taken along the line 5-5, of the filter device and flow distributor seen in FIG. 1.

FIG. 6a is a partially enlarged side view of a projecting support member and filter housing, here showing the support member as unitary with the filter housing.

FIG. 6b is a partially enlarged side view of the projecting support member shown in FIG. 6a, but here rotated 90 degrees.

FIG. 7 is a partially enlarged side view of a portion of the filter device and flow distributor seen in FIG. 5, here showing a flow path of biological liquid through the filter media adjacent the projecting support member.

FIG. 8 is a perspective view of the filter device seen in FIG. 1, in combination with an operational assembly including a blood supply bag, a blood receiving bag, and an air bag useable in accordance with the principles of the present invention for flowing a biological liquid through the device and assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly FIGS. 1-4 for example, there is depicted an improved flow distributor 10 for use with a biological liquid filter device 12. The device 12 may include a filter housing 16, a filter media 32 (preferably comprising a number of layers of filter material as known in the art) and a closure member 34. Such a device 12 is preferably constructed according to the teachings

disclosed in U. S. Serial No. 08/812, 717, filed March 6, 1997 and entitled :"In-line Gravity Driven Liquid Filtration Device Usable to Filter Blood or Blood Products"which is hereby incorporated by reference and made a part of the disclosure herein. Additionally, the filter device 12 may be constructed as disclosed in U. S. Patent No. 5, 472, 605, entitled"A Filtration Device Usable for Removal of Leukocytes and Other Blood Components"issued December 5,1995, or the filter device disclosed in U. S. Serial No. 08/524, 049, entitled"An In-Line Liquid Filtration Device Usable for Blood, Blood Products and the Like"filed September 6,1995, all of which are hereby incorporated by reference and made a part of the disclosure herein.

As referred to herein, the terms upstream, top or up refer to a location of the flow of liquid prior to filtration through filter media 32 within the filter device 12. Conversely, the terms downstream, bottom or down as used herein refer to a location of the flow of liquid after filtration through any portion of the filter media within the filter device.

As disclosed herein, the filter device 12 is preferably disc or cylindrical shaped and intended to be used for in-line gravity filtration. The filter device may be used for the filtration of various liquids including biological liquids. However, it is particularly suited for the filtration of blood and/or blood products and will be described herein in reference to blood filtration.

In the figures, the improved flow distributor 10 is shown as a preferable unitary structure with the

filter housing 16, which is part of the filter device 12. Such could be achieved by molding, i. e., plastic injection molding or the like, as well know in the art.

Differently, and alternatively, flow distributor 10 could comprise a separate structure to be mated or joined with the filter housing by conventional means, and such would be in accordance with the principles of the present invention.

Generally, the flow distributor 10 comprises a projecting support member 14 where the support member is joined with the filter housing 16. Preferably the flow deflector comprises a plurality of members, each of the plurality of members comprising the projecting support member. Still further preferably, the support member 14 is joined with the filter housing 16 by forming the two together, such as by molding them as a unitary structure by injection molding or the like as well known in the art. For discussion purposes, reference to the support member 14 also includes reference to the plurality of support members, unless stated differently.

Referring to FIGS. 6a and 6b for example, there is particularly depicted the projecting support member 14 with an upper surface 17. For example, the upper surface may have a first upper section 18 pitched downwardly in at least a first direction, and preferably two directions, along a length 20. Further, the upper surface 14 may have a second upper section 22 pitched downwardly in at least a second direction, and preferably two directions, along a width 24.

Preferably, the first and the second directions of pitch of the respective upper sections 18 and 22 are

non-parallel relative to each other. Even more preferably, the first upper section 18 and the second upper section 22 also at least partially intersect.

Most preferably, the first direction of pitch of the first section 18 is also perpendicular to the second direction of pitch of the second section 22.

As used herein, downwardly generally means pitch sloping towards the body 15 of the projecting member 14. The upper surface 17 generally comprises that portion of the projecting member facing away from the body 15 in an upward direction relative thereto. The upper sections 18 and 22 could comprise a line or a surface smaller than the upper surface 17 or be co- extensive with portions of the surface 17. For example, slope of the section 18 could define a straight line or flat surface, but is preferably curved and most preferably a smooth curve curved in two opposite directions (i. e., away from each other) along the length 20 wherein an apex of the upper surface 17 is located above the center of the length 20. As another example, slope of the section 22 could be a straight line or flat surface, but is preferably curved and most preferably a smooth curve curved in two opposite directions (i. e., away from each other) along the width 24 where an apex of the upper surface 17 is located above the center of the width 24. It is understood that the apex of the sections 18 and 22 could be the same or different and either way the apex (es) could be off center for both or either sections 18 and 22, and the claimed features and advantages of the invention would still be obtained. Additionally, the pitch need not be continuous over the surface 17. Although any variety of lines, flat

surfaces and curved surfaces could define the upper surface 17, most preferably the sections 18 and 22 comprise smooth curved intersecting surfaces wherein the upper surface 17 is generally dome shaped.

In the figures, the support member may be joined with the filter housing on a same side 26 of the filter device. Preferably the same side is an upstream side 26 of the filter device. Each member of the plurality of support members is preferably spaced from another member of the plurality of members. Additionally, a longitudinal axis parallel with the length 20 (FIG. 6a) of each of the plurality of members is preferably oriented in a non-parallel relationship with the longitudinal axis of at least one other adjacent member of the plurality of members. Most preferably, the non- parallel relationship comprises a perpendicular relationship (FIG. 3).

In exploded view as shown in FIG. 2, the assembled filter device 12 (FIG. 1) may include the flow distributor 10 and the filter media 32. The filter media may contact at least one support member 14 and preferably contacts each member of the plurality of support members 14. Additionally, the filter device may include a closure member 34 and the filter media may be positionable between the filter housing 16 and the closure member 34. In this way, preferably a space 36 (FIG. 4) adjacent the plurality of members 14 is maintained between the filter media 32 and the filter housing 16 and a flow path 38 adjacent the support member is maintained through the filter media 32 (FIG.

7).

Other features of the invention concern a method for flowing biological liquid in the filter device 12, which device 12 may including the filter media 32 and the filter housing 16. A first step (FIG. 2) in the method may be supporting the filter media in contact with at least one projecting support member 14, which support member is joined with the filter housing 16 as previously discussed. Supporting preferably includes a plurality of members, each of the plurality of members comprising the support member and each of the plurality of members being spaced from another of the plurality of members.

Next, the method may comprise (FIG. 5) compressing the filter media within the filter device with a compression force. Particularly excellent results are obtained when the compression force is supplied by a relationship between the filter housing 16, the flow distributor 10, the filter media 32 and the closure member 34. For example, the filter media is preferably thick enough so that it is forcibly sandwiched between the upper sections of the support member and the closure member (FIG. 5).

Then, the method preferably includes distributing a portion of the compression force to the support member wherein the filter media 32 is spaced from the filter housing by the support member 14 and adjacent the support member 14 flow path 38 is maintained through the filter media 32 during flow of biological liquid through the device 12 and through the filter media 32 (FIG. 7).

An additional step the method may include comprises forming at least one support member and the filter housing as a unitary structure (FIG. 4). Yet another step may comprise flowing biological liquid (generally shown as flow arrows in FIGS. 5 and 7) through the filter device and filtering the biological liquid as it flows through the filter media. Still other features of the method relate to configurations for the support member, e. g., orientations of the pitched first and second sections 18 and 22, and, the orientation of the plurality of support members relative to one another and relative to the filter housing, all similar to that discussed previously.

In FIG. 8, the filter device 12 of FIG. 1 is depicted in operational assembly with inlet tubing 217, outlet tubing 218, feed blood bag 293, receiving blood bag 294, air bag 295, inlet tube clamp 266, outlet tube clamp 267, and air tube clamp 268. Preferably, the user will purchase the assembly of FIG. 8 sterilized without feed blood bag 293 with the inlet end of inlet tubing 217 sealed or coupled with a conventional spike cover assembly or other conventional means to maintain system sterility. For performing filtration, inlet tube clamp 266, preferably located close to the inlet end of inlet tubing 217, is closed. Next the outlet tube clamp 267 is opened and air tube clamp 268, preferably located close to the air tube port on receiving blood bag 294, is closed. Inlet tubing 217 attached to inlet port 27 of upstream side 26 is now attached to feed blood bag 293 using a sterile docking device or by a conventional spike connection or similar means, as is well known in the art. Once the

connection is made feed blood bag 293 may be hung from hook 297 on blood bag pole 296. Receiving blood bag 294 and air bag 295 should be placed on a surface such as a table top or the like. The inlet tube hanging tab 211 positions inlet tubing 217 and outlet tubing 218, respectively, so that filtration device 12 preferably hangs vertical and plumb.

Still referring to FIG. 8, filtration is performed as follows. Inlet tube clamp 266 is opened so that gravity now forces blood to flow from feed blood bag 293, through inlet tubing 217, through inlet port 27 of upstream side 26, through the space 36 (FIG. 5), through the filter media 32 adjacent and more distant from the support member 14 (FIG. 7) as the blood filters toward closure member 34, and into the outlet port 35 (FIG. 5) of the closure member, into the connected outlet tubing 218, etc. to bag 294 as desired. The blood preferably flows through the filter device 12 utilizing one or more of the method steps previously discussed for flowing biological liquid through the filter device. Blood filtration will continue until feed blood bag 293 is empty. When feed blood bag 293 is empty it will be collapsed and therefore close the inlet end of inlet tubing 217. Air venting features may be utilized, as disclosed in U. S.

Serial No. 08/812, 717, but such features are merely preferred and not essential to the practice of the present invention. Such an air vent, if desired, would generally be located at air vent port 40 (FIG.

3).

Referring to FIGS. 8 and 3, for example, another feature of the invention that may be preferably practiced when operating the system is orienting the longitudinal axis (i. e., along the length 20) of each of the plurality of members 14 in a non-perpendicular relationship with a vertical axis 13 (FIG. 3) of the filter device in reference to positioning in FIG. 8.

In the present embodiment, the vertical axis 13 happens to correspond with the tab 211. However, the critical aspect in this regard is that the longitudinal axis of each member 14 is oriented relative to the vertical positioning of the filter device when in use, regardless what structure is specifically used to support the filter device (e. g., the tab 211 in this embodiment). Such an orientation is most preferably a 45° angular relationship between the longitudinal axis of the support member 14 and the vertical axis 13 (FIG.

3) of the filter device in reference to positioning in FIG. 8. This preferred orientation and relationship better minimizes the possibility of air entrapment during filtration, and particularly during initial filling of the filter device with blood in space 36.

Still referring to FIG. 8, during filling, the filter device is preferably vertically plumb with the hanging tab 211 pointing upward. Then, the device is preferably gravity driven and fills on the inlet side 26 from the bottom up, displacing resident air as it fills. If the members 14 are in the preferred 45° angular relationship, air entrapment beneath or under each projecting member 14 is reduced. This advantageously results in less air entrapment in the filter device which thereby maximizes the upstream area

of the filter media 32 available to pass blood therethrough for filtration.

As various possible embodiments may be made in the above invention for use for different purposes, and as various changes might be made in the embodiments above set forth, it is understood that all of the above matters here set forth or shown in the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.