Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims priority to U.S. Provisional Application Ser. No. 60/068,250, filed in the U.S. Patent and Trademark Office on Dec. 19, 1997, by Lewis et al., the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved filter, and more particularly to a gross filter for use in a drainage device. Specifically, the present invention relates to a gross filter with an open face that is configured to lessen filter blockage by gross particulate matter, for example blood clots, entrained in incoming fluid while also permitting a clear view of blood clot volume retained inside the filter. 
     2. Prior Art 
     Gross filters for use in filtering out large particulate matter entrained in body fluids drained from a patient during convalescence or post-operative recovery are well known in the art. Typically, gross filters of this kind are incorporated in a drainage device, for example a Chest Drainage Unit (CDU), for filtering blood clots and other gross contaminates from body fluids before reinfusing such fluids back to the patient. 
     A CDU is an apparatus for suctioning gases and liquids from the pleural cavity of a patient in order to re-expand the patient&#39;s lungs. The pleural cavity lies within the rib cage above the diaphragm and is surrounded by the pleural membrane. The pleural cavity contains both lungs, which in their normal expanded state fill the pleural cavity. Several conditions and diseases such as interventional surgery, trauma, emphysema and various infections can cause a build up of liquid and gases around the lungs in the intrapleural space. When this happens, it causes the lungs to collapse to a volume much less than that of the pleural cavity, thereby severely impairing breathing functions of the patient. The lungs can be re-expanded to their normal state to fill the pleural cavity by draining the liquid and gases from the intrapleural space using the CDU. A typical CDU and its operation is disclosed in U.S. patent application Ser. No. 08/810,056 to Swisher et al. entitled “Chest Drainage Unit with Controlled Automatic Excess Negativity Relief Feature”, assigned to the assignee, and is herein incorporated by reference in its entirety. 
     During the draining of fluid from a patient&#39;s pleural cavity blood clots may develop and become entrained in the fluid as it enters the collection chamber of the CDU for eventual reinfusion to the patient. During reinfusion of blood, it is desirable that the collected blood be free of any large particulate matter or other kinds of gross contaminants before entering and collecting at the bottom portion of the collection chamber. In order to screen out these undesirable contaminants a gross filter is provided near the inlet to the collection chamber for filtering out large particulate matter as fluid enters the CDU. The Swisher et al. device referenced above is generally exemplary of medical drainage devices that incorporate a gross filter for filtering out blood clots and other large particulate matter from fluid drained from a patient&#39;s pleural cavity. The gross filter used in the Swisher et al. device comprises a porous filtering material placed near the inlet of the collection chamber in a horizontal orientation so that all incoming fluid must pass through the gross filter before collecting in a pooling area located at the bottom portion of the collection chamber. In this manner, incoming fluid is filtered prior to entering the pooling area so that blood clots and other large particulate matter are retained on top of the filter. 
     Unfortunately, the gross filter of the Swisher et al. device suffers from several drawbacks. First, blood clots that are filtered out and retained inside the gross filter will begin to block and impede the flow of fluid being filtered as blood clots begin to accumulate and spread over the surface area of the filter, thereby wasting blood that could be reinfused back to the patient. Second, the gross filter of the Swisher et al. device is made from a reticulated foam material which has a tendency to separate into smaller fragments when trimmed for the size required to properly fit into the collection chamber, thus causing possible contamination of already filtered fluid by these separated fragments. 
     As of yet, nothing in the prior art has addressed the problem of developing an improved gross filter made of a solid unitary construction that advantageously prevents total blockage of the filter by gross contaminants while also addressing the need for a gross filter that permits clear viewing and accurate visual measurement by medical personnel of the volume level of gross contaminants retained in the filter. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The principal object of the present invention is to provide a gross filter having a configuration that inhibits or prevents the total blockage of the filter by large particulate matter and other contaminants. 
     Another object of the present invention is to provide a gross filter that filters out large particulate matter, for example blood clots, before collection in the collection chamber. 
     A further object of the present invention is to provide a gross filter that permits clear visual measurement by medical personnel of the amount of large particulate matter and other gross contaminants retained inside the filter. 
     Another principal object of the present invention is to provide a means for channeling incoming fluid through a portion of the gross filter in order to prevent total blockage of the gross filter. 
     These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation. The preferred embodiment provides for a gross filter comprising a bottom panel, two side panels, and a back panel that collectively form a filter body having a generally rectangular cross-section. The filter body is configured so as to have open top and front portions, angled back and side panels, and a slanted bottom panel that forms an angled slope towards one end of the gross filter. Alternatively, the gross filter may have other shapes that include, but are not limited to, semicircular/conical or diamond shaped, with open front and top portions, which are suitable for filtering gross contaminants from incoming fluid. 
     The angled back and side panels of the filter body are configured so as to prevent total blockage of the filter body by channeling blood clots to one end thereof. The back and side panels are configured such that gravity will force blood clots to one portion of the gross filter due to their set angle. This type of angled configuration ensures a sufficient filtration rate through the gross filter when the bottom panel is partially or totally blocked with large particulate matter and promotes a maximum filtration rate when there is no blockage of the filter body present. A guide is provided on the interior portion of the gross filter&#39;s back panel for channeling incoming fluid toward one portion of the gross filter in order further prevent total blockage. A gutter ledge is provided along the top portion of the back panel for channeling incoming fluid towards one portion of the filter body that contacts the top portion of the back panel between the guide and the side panel under the inlet port. 
     The open front portion of the gross filter is positioned adjacent a partially transparent front wall of the CDU and allows for unobstructed viewing of the interior portion of the gross filter when large particulate matter entrained in incoming fluid are screened out and retained therein. Where large particulate matter has blocked the back, side and back panels of the gross filter, an overflow panel is provided for filtering fluid that overflows the interior portion of the gross filter or when the overflow of the entire first subchamber occurs. 
     The gross filter of the present invention is adapted for placement adjacent or near the inlet port inside a collection chamber of a drainage device, such as a CDU, for filtering incoming fluid of large particulate matter and other gross contaminates entrained therein. Preferably, the CDU is of the type that includes a collection chamber that comprises two or more subchambers that communicate through an overflow port with the gross filter located so that incoming fluid is filtered into the first subchamber and overflow fluid is filtered into the second or additional subchambers, if required. The gross filter is disposed inside the first subchamber and retained therein by an arrangement of grooves and a support member that are adapted to engage retaining ledges formed on the gross filter such that the front edges of both side panels of the gross filter are positioned flush against the front wall of the CDU. The portion of the front wall of the CDU in the area where the gross filter is located includes a clear viewing area of the interior portion of the gross filter and is provided with appropriate indicia adapted for accurate visual measurement of the volume of large particulate matter retained inside the interior portion of the gross filter by a user. A splash guard is provided on the interior portion of the first subchamber near the inlet port for channeling incoming fluid from the inlet port between the guide and the side panel so that incoming fluid is not allowed to freely flow into the gross filter. This channeling of incoming fluid by the splash guard and guide acting together prevents total blockage of the filter body. The gross filter further comprises an overflow portion that is positioned such that fluid that overflows through the first subchamber is filtered before entering the second subchamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the preferred embodiment of the gross filter according to the present invention; 
     FIG. 2 is a plan view of the various panels that comprise the gross filter shown in FIG. 1 according to the present invention; 
     FIG. 3 is a side view of the gross filter shown in FIG. 1 illustrating the angled bottom and back panels according to the present invention; 
     FIG. 4 is a side view of the gross filter shown in FIG. 1 illustrating the overflow portion of the gross filter according to the present invention; 
     FIG. 5 is a partial cut-away of the first and second subchambers of the Chest Drainage Unit illustrating the groove and support member arrangement used to retain the gross filter shown in FIG. 1 inside the first subchamber according to the present invention; 
     FIG. 6 is a partial cut-away of the first subchamber of the Chest Drainage Unit illustrating the groove and support member arrangement used to retain the gross filter shown in FIG. 1 inside the first subchamber according to the present invention; 
     FIG. 7 is a front view of the gross filter shown in FIG. 1 disposed in the first subchamber of the Chest Drainage Unit illustrating the various flow pathways according to the present invention; 
     FIG. 8 is a bottom view of the gross filter shown in FIG. 6 according to the present invention; 
     FIG. 9 is a perspective view of the Chest Drainage Unit illustrating the measuring indicia provided on the front wall for visually measuring the volume of large particulate matter retained inside the gross filter according to the present invention; 
     FIG. 10 is a perspective view of an alternative embodiment of the gross filter shown in FIG. 1 according to the present invention; and 
     FIG. 11 is a perspective view of another alternative embodiment of the gross filter shown in FIG. 1 according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, the preferred embodiment of the gross filter of the present invention is illustrated and generally indicated as  10  in FIG.  1 . As shown in FIG. 1, gross filter  10  includes a filter body  19  that comprises a back panel  12 , first and second side panels  14  and  16 , bottom panel  18 , and open front and top portions  15  and  17 . Gross filter  10  is disposed inside a Chest Drainage Unit  11  (CDU) (FIG. 7) for filtering incoming fluid drained from a patient. Preferably, CDU  11  is a drainage device as disclosed in U.S. patent application Ser. No. 08/810,056 entitled “Chest Drainage Unit with Controlled Automatic Excess Negativity Relief Feature”, assigned to the assignee, and is incorporated by reference in its entirety. 
     Referring to FIG. 2, a plan view of the panels  12 ,  14 ,  16  and  18  showing the interior side  31  of gross filter  10  is shown. Each panel  12 , 14 ,  16  and  18  comprises a filter matrix  34  having a porosity sufficient for filtering fluid, for example blood, of blood clots and other gross contaminates as fluid passes through filter body  19 . Preferably, filter matrix  34  includes, but is not limited to, a continuous pattern of rectangular or square-shaped designs, although any pattern, such as triangles, diamonds, circles, or crosses, which are suitable for filtering fluid of gross contaminates is felt to fall within the scope of the present invention. 
     Gross filter  10  comprises a generally rectangular-shaped planar back panel  12  defined by angled head edge  47 , base edge  49 , and generally angled opposing inner edges  51  and  53 . A guide  24  is provided along the interior surface  31  for channeling incoming fluid to a specific portion of gross filter  10  in order to prevent total blockage of the filter body  19  by channeling any blood clots that are entrained in incoming fluid toward one portion of body  19 . Preferably, both inner edges  51  and  53  extend away from base edge  49  at approximately 100 degree angle, although the angle may range between 90 and 120 degrees. Head edge  47  extends away from inner edge  51  at approximately a 90 degree angle where edge  47  terminates in a notch  35 . 
     Inner edge  51  may be integrally formed with or attached to inner edge  48  of first side panel  14 . First side panel  14  is located adjacent to back panel  12  and is defined by head edge  42 , angled base edge  44 , free edge  46  and angled inner edge  48 . Base edge  44  extends away from inner edge  48  at approximately a 100 degree angle. Although the angle formed between base edge  44  and inner edge  48  is preferably 100 degree angle, the angle may range between 90 and 120 degrees. 
     Inner edge  53  of back panel  12  may be integrally formed with or attached to inner edge  56  of second side panel  16 . Opposed to first side panel  14  with respect to back panel  12  is second side panel  16  which is defined by free edge  41 , left free edge  43 , head edge  50 , angled base edge  52  and right free edge  54 . Head edge  50  extends away from inner edge  56  at an 85 degree angle, although the angle may range between 90 degrees and 75 degrees. Preferably, base edge  52  extends away from inner edge  56  at a 100 degree angle, although the set angle may range between 90 and 120 degrees. 
     Base edge  49  may be integrally formed with or attached to head edge  55  of bottom panel  18 . Bottom panel  18  is located adjacent to back panel  12  and is defined by head edge  49 , opposed right and left free edges  57  and  59 , and base edge  63 . An opening  38  is formed through the bottom panel  18  for receiving therethrough a conduit for the egress of fluid from collection chamber  13 . 
     As illustrated back in FIG. 1, first and second side panels  14  and  16  may include a reinforcing bar  36  that extends the entire length of each panel  14  and  16  from the back panel  12  to free edges  46  and  54 , respectively, and provides structural reinforcement to filter body  19 . Each side panel  14  and  16  further includes a side spacer  22  that is spaced slightly inward from free edges  46  and  54  and extends in perpendicular relationship to the exterior surface  33  of each respective side panel  14  and  16 . Second side panel  16  comprises an overflow portion  20  that extends from the main body of panel  16  and is adapted to filter any fluid that may overflow from gross filter  10 . Overflow portion  20  includes a filter matrix  34  that extends in perpendicular relation from overflow portion  20  and borders the entire periphery of portion  20 . Overflow filter  32  provides additional filtering for initially filtered fluid that flows from between the filter body  19  and the wall of the collection chamber, as shall be explained in greater detail later. 
     First side panel  14  further comprises a first retaining ledge  26  along head edge  42  (FIG. 3) that includes a flange  40  that extends in perpendicular relationship with respect to ledge  26 . As shall be explained in greater detail below, first retaining ledge  26  provides a connection site for securely retaining gross filter  10  inside CDU  11 . Similarly, second side panel  16  includes a second retaining ledge  28  along head edge  50  (FIG. 4) that runs along the upper portion of panel  16  until ledge  28  meets overflow portion  20 . Second retaining ledge  28  also forms a flange  40  that is in perpendicular relationship to ledge  28  and is adapted to securely retain gross filter  10  inside CDU  11 . 
     As shall be illustrated later, bottom panel  18  slants downward from back panel  12  to base edge  63  of bottom panel  18  so as to channel fluid flow through specific portions of filter body  19  and inhibit free flow therethrough. The channeling of incoming fluid prevents total blockage of back panel  12  by forcing blood clots toward the front end of bottom panel  18  near base edge  63  so more accurate graduations of accumulated blood clots can be made by the user while leaving the remaining portion of panel  12  unblocked for filtering of incoming fluid. The upper portion of back panel  18  includes a gutter ledge  30  which is set at an angle that runs from first side panel  14  to notch  35  (FIG. 2) so that incoming fluid that is captured by ledge  30  gravity flows toward the first side panel  14  end of ledge  30  and then flows down between guide  24  and first side panel  14 . Gutter ledge  30  effectively forms a conduit adapted for capturing incoming fluid along the back portion of filter body  19  and channeling it towards one end of body  19 . 
     Referring to FIGS. 3 and 4, opposite side views of gross filter  10  are shown illustrating the angled orientations of back panel  12  and bottom panel  18 . Inner edges  48  and  56  of first and second side panels  14  and  16 , respectively, are both set at the same angle in relation to free edge  46  and right free edge  54 . As such, back panel  12  has a set angle that exposes the interior surface area of panel  12  to filtering of incoming fluid as it enters CDU  11  and passes through filter body  19 . 
     As further illustrated in FIGS. 3 and 4, base edges  44  and  52  of first and second side panels  14  and  16 , respectively, are set at the same angle such that bottom panel  18  forms a flat surface angled toward the open front portion  15  (FIG.  1 ). This angled orientation of bottom panel  18  forces blood clots and other gross contaminants towards the open front portion  15  of filter body  19 , thereby leaving the back end portion of panel  18  unblocked. This sloped orientation of bottom panel  18  exposes a larger area of panel  18  to filtering of incoming fluid so that sufficient area of panel  18  is provided for filtering when other areas of panel  18  become clogged by blood clots and other large particulate matter retained inside filter body  19 . 
     As illustrated in FIG. 7, first and second side panels  14  and  16  are preferably set at an angled orientation to one another so that the bottom portions of both panels  14  and  16  are angled slightly toward each other. However, other angled orientations such as having the top portion of first and second side panels  14  and  16  angled toward each other or having just one side panel  14  or  16  angled either toward or away from the other panel  14  or  16 , which remains straight, is felt to fall within the scope of the present invention. The angled orientation of the first and second side panels  14  and  16  provide alternative filtration sites to incoming fluid flow. 
     Referring to FIG. 8, bottom panel  18  will be discussed in greater detail. An opening  38  is formed through bottom panel  18  and is adapted for receiving a conduit (not shown) therethrough for the transport of filtered fluid from collection chamber  13 . In order properly orientate gross filter  10  inside collection chamber  13  during insertion of the filter into CDU  11  during manufacturing, a pair of side and back spacers  22  and  23 , respectively, are provided along the bottom portion of first and second side panels  14  and  16 . Side spacers  22  are integrally formed with or attached to the front portion of bottom edges  44  and  52 , respectively, using a suitable adhesive, and extend therefrom in a perpendicular relation to each panel  14  and  16 , so that lateral movement against the walls of the collection chamber  13  is prevented. Back spacers  23  are also integrally formed with or attached to the back portion of bottom edges  44  and  52 , respectively, and are at a set angle in relation to back panel  12 , so as to prevent backward and forward motion of filter body  19  inside CDU  11 . Preferably, the angle set for back spacers  23  is 110 degrees in relation to back panel  12 , although any angle between 50-120 degrees is felt to fall within the scope of the present invention. 
     Referring to FIGS. 5 and 6, the interior portions of CDU  11  which house gross filter  10  will be discussed in greater detail. CDU  11  comprises a collection chamber  13  that includes first subchamber  68  in fluid flow communication with a second subchamber  70  through an overflow panel  72  formed therebetween. First subchamber  68  comprises opposing first and second side walls  62  and  64 , back wall  60 , front wall  61  (FIG.  9 ), top wall  67  and bottom wall  66 . An inlet port  58  adapted for permitting fluid flow into first subchamber  68  is formed through top wall  67 . 
     Gross filter  10  is housed and securely retained inside first subchamber  68  through an arrangement of grooves formed on the interior surfaces of first and second side walls  62  and  64  of first subchamber  68 . A first upper groove  74  in combination with a first lower groove  76  are provided on the first side wall  62  and are adapted to engage first retaining ledge  26  of first side panel  14 . Similarly, a second upper groove  80  in combination with a second lower groove  82  are provided on second side wall  64  and are adapted to engage second retaining ledge  28  of second side panel  16 . A third groove  84  is provided above the third upper and lower grooves  80  and  82  and is adapted to retain overflow portion  20  of second side panel  16  when gross filter  10  is housed inside first subchamber  68 . 
     During manufacturing gross filter  10  is inserted into first subchamber  68  before the front wall  61  is attached to CDU  11 . To engage and retain gross filter  10  inside first subchamber  68 , retaining ledges  26  and  28  of gross filter  10  are inserted through and engaged to grooves  74 ,  76  and  80 ,  82 , respectively, formed on the first and second sidewalls  62  and  64  of first subchamber  68 . As shown in FIG. 7, flanges  40  of first and second retaining ledges  26  and  28  are inserted through the respective slots formed between the upper and lower grooves  74  and  76  and upper and lower grooves  80  and  82 . Concurrently, overflow panel  32  is inserted through the slot formed by third upper groove  84  so that gross filter  10  is securely retained inside first subchamber  68  and flush against the front portion of CDU  11 . A support member  78  (FIGS. 5,  6  and  8 ) forming a straight lateral ledge extending from back wall  60  is provided for supporting bottom panel  18  of filter body  19  inside first subchamber  68  once body  19  has been inserted therein. Once gross filter  10  has been inserted and retained inside CDU  11 , the front wall  61  is attached to the front portion of CDU  11  using an adhesive bond or other suitable means of attachment including, but not limited to, ultrasonic welding or riveting. 
     Referring to FIG. 7, the fluid flow pathway of incoming fluid into first subchamber  68  and through gross filter  10  is illustrated. Flow pathway A 1  demonstrates the path of incoming fluid directly into collection chamber  13  as incoming fluid is channeled downward by splash guard  86  through the open top portion of filter body  19 . As discussed above, once incoming fluid enters filter body  19 , gutter  30  diverts any incoming fluid that may contact the back portion of filter body  19  toward one end of gross filter  19 , as illustrated by flow pathway A 2 . Guide  24  is provided for further channeling incoming fluid toward one end of bottom panel  18  so as to inhibit the total blockage of panel  18  by continually wetting a portion of filter body  18  which prevents drying and caking of fluid over filter matrix  34 . 
     As incoming fluid is channeled through filter body  19  it may follow basically one of two flow pathways as incoming fluid is filtered. Flow pathways A 3  and A 6  show filtration of incoming fluid through first and second side panels  14  and  16 , respectively, when total blockage of bottom panel  18  occurs, while flow pathway A 4  illustrates the filtration of incoming fluid through the back panel  12  under similarly blocked circumstances. Finally, flow pathway A 5  illustrates the pathway of incoming fluid through bottom panel  18 . 
     Although most of the incoming fluid is filtered through bottom panel  18  due to the channeling effect of the guide  24  and splash guard  86 , the angled orientations of first and second side panels  14  and  16  and back panel  12  provide secondary filtration areas when the bottom panel  18  becomes clogged with large particulate matter which are retained inside the filter body  19 , thereby preventing fluid flow therethrough for filtering incoming fluid. In such instances, the above-identified secondary filtration areas provide unimpeded filtration of incoming fluid when the bottom panel  18  becomes blocked. Flow pathways A 3 , A 4  and A 6  illustrate the potential alternate pathways that incoming fluid may follow when flow pathway A 5  is interrupted due to blockages that may occur at bottom panel  18 . 
     Referring to FIG. 9, measuring indicia  88  used to visually ascertain the volume of large particulate matter retained inside gross filter  10  is illustrated. The measuring indicia  88  is provided on the front wall  61  of CDU  11  adjacent to a window  90  which shows the interior portion of gross filter  10  so that a nurse or other medical personnel may visually ascertain the volume of large particulate matter retained inside filter body  19 . Preferably, measuring indicia  88  is a combination of numerical indicators with respective markers that highlight specific volume levels, although numerical indicators or markers alone may be used. During manufacturing indicia  88  may be silk screened directly on the front wall  61 , as in the preferred embodiment, or in the alternative, a label may be applied to the front wall  61  using a suitable adhesive. 
     FIGS. 10 and 11 illustrate alternative shapes of filter body  19  according to the present invention. As shown in FIG. 10, filter body  119  has a triangular shape that channels incoming fluid flow in order to prevent total blockage of body  119  while permitting a clear view of the volume of gross particular matter retained therein. 
     Filter body  119  comprises a generally rectangular-shaped first side panel  121  defined by angled base edge  131 , head edge  141 , free edge  129  and inner edge  145 . Preferably, base edge  131  is set a 10 degree angle with respect to edge  141 , although the angle may range from 1 degree to 15 degrees. 
     Base edge  131  may be integrally formed with or attached to first side edge  133  of bottom panel  125 . Bottom panel  125  has a generally triangular shape and is defined by first side edge  133 , second side edge  135  and free edge  147 . Similar to filter body  19 , bottom panel  125  of filter body  119  is set at an angle so that the entire panel  125  slants slightly downward from the point where first and second side edges  131  and  135  meet to free edge  147 . This downward slant of bottom panel  125  ensures that blood clots and other gross particular matter gravity flows toward, and accumulates at, the front portion of filter body  119 . 
     Second side edge  135  is integrally formed with or attached to base edge  137  of second side panel  123 . Second side panel  123  has a generally rectangular shape and is defined by angled base edge  135 , inner edge  139 , head edge  143  and free edge  147 . Preferably, base edge  135  is set at the same 10 degree angle as base edge  131  of first side panel  121 , although the angle may range from 1 degree to 15 degrees. Inner edge  139  may be integrally formed with or attached to inner edge  145  of first side panel  121 . Both head edges  141  and  143  of first and second side panels  121  and  123 , respectively, include a retaining ledge  127  which may be integrally formed with or attached thereto. Retaining ledge  127  provides a means for retaining filter body  119  inside the collection chamber  13  by engaging ledge  127  to a support member (not shown) provided along the wall of first subchamber  68 . 
     Referring to FIG. 11, filter body  219  has a semi-circular/conical shape with the conical configuration of body  219  slightly tapered inward. Filter body  219  comprises a semi-circular panel  221  that is defined by free edge  225  which forms a generally rectangular shape with an open top portion. Semi-circular panel  221  is defined by head edge  229 , free edge  225  and base edge  331 . Head edge  229  forms a semi-circular shape with a similarly shaped retaining ledge  227  integrally formed with or attached to edge  229 . Retaining ledge  227  also provides a means for retaining filter body  219  inside collection chamber  13  by engaging ledge  227  to a support member (not shown) provided along the wall of first subchamber  68 . Base edge  331  may be integrally formed with or attached to a generally semi-circular shaped head edge  333  of bottom panel  223 . Bottom panel  223  has a generally semi-circular shape defined by head edge  333  and free edge  225 . Similar to filter body  119 , bottom panel  223  of filter body  219  is set at an angle so that the entire panel  223  slants slightly downward toward free edge  225 . This downward slant of bottom panel  223  ensures that blood clots and other gross particular matter gravity flows toward, and accumulates at, the front portion of filter body  219 . 
     It should be understood from the foregoing that, while particular embodiments of the invention have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the invention. Therefore, it is not intended that the invention be limited by the specification; instead, the scope of the present invention is intended to be limited only by the appended claims.

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