Abstract:
A portable system for subatmospheric pressure therapy in connection with healing a surgical wound includes a wound dressing dimensioned for positioning relative to a wound bed and a collection canister in fluid communication with the wound dressing. The canister includes a first vacuum chamber for drawing a vacuum and a second fluid chamber for collecting fluids removed from the wound dressing under the vacuum. The canister further includes a hydrophobic membrane separating the first and second chambers. The hydrophobic membrane is dimensioned to span a major portion of the cross-sectional area of the canister. The hydrophobic membrane may be dimensioned to substantially span an internal dimension of the collection canister. The hydrophobic membrane may include one or more outwardly extending lobes. The hydrophobic membrane may be releasably mountable to the canister, and, may be supported within a divider separating the first vacuum chamber and the second fluid chamber.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to treating an open wound, and, more specifically, relates to a wound therapy system including a portable container having a hydrophobic membrane configured to maximize fluid capacity of the container. 
         [0003]    2. Background of Related Art 
         [0004]    Wound closure involves the migration of epithelial and subcutaneous tissue adjacent the wound towards the center and away from the base of the wound until the wound closes. Unfortunately, closure is difficult with large wounds, chronic wounds or wounds that have become infected. In such wounds, a zone of stasis (i.e. an area in which localized swelling of tissue restricts the flow of blood to the tissues) forms near the surface of the wound. Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only receive diminished oxygen and nutrients, but, are also less able to successfully fight microbial infection and, thus, are less able to close the wound naturally. Such wounds have presented difficulties to medical personnel for many years. 
         [0005]    Negative pressure therapy also known as suction or vacuum therapy has been used in treating and healing wounds. Application of negative pressure, e.g. reduced or subatmospheric pressure, to a localized reservoir over a wound has been found to assist in closing the wound by promoting blood flow to the area, stimulating the formation of granulation tissue, and encouraging the migration of healthy tissue over the wound. Negative pressure may also inhibit bacterial growth by drawing fluids from the wound such as exudates, which may tend to harbor bacteria. This technique has proven particularly effective for chronic or healing-resistant wounds, and is also used for other purposes such as post-operative wound care. 
         [0006]    Generally, negative pressure therapy provides for a wound to be covered to facilitate suction at the wound area. A conduit is introduced through the wound covering to provide fluid communication to an external vacuum source. Atmospheric gas, wound exudates, or other fluids thus may be drawn from the reservoir through the fluid conduit to stimulate healing of the wound. Exudates drawn from the reservoir may be deposited in a collection canister or container. 
       SUMMARY 
       [0007]    The present disclosure is directed to further improvements in negative or subatmospheric pressure therapy. In one embodiment, a subatmospheric pressure therapy system includes self-contained collection canister defining a cavity or chamber for receiving fluid, a vacuum source, and a power source. The vacuum source and fluid receiving cavity may be separated by a hydrophobic filter or membrane. The hydrophobic membrane prevents the aspiration of fluid into the vacuum source. The collection canister of the present disclosure may be placed on its side, tilted or possibly even inverted without affecting operation of the system. This is in contrast to current non-ambulatory fluid collection systems incorporating fluid receptacles which must be in a standing or upright position during operation. In such systems, once a sufficient volume of fluid has been collected in the canister, tipping or tilting of the canister causes the fluid in the canister to cover the hydrophobic membrane. When the hydrophobic membrane is covered by fluid, air is prevented from passing through the membrane, thereby blocking the suction provided by the vacuum source. Without suction, the wound therapy system is ineffective at drawing fluid from the wound. The problem of the hydrophobic membrane becoming covered by fluids may be further exaggerated in portable units which may be worn or carried by the subject. 
         [0008]    In one embodiment, a portable system for subatmospheric pressure therapy in connection with healing a surgical wound includes a wound dressing dimensioned for positioning relative to a wound bed of a subject and a collection canister in fluid communication with the wound dressing. The canister includes a first vacuum chamber for drawing a vacuum and a second fluid chamber for collecting fluids removed from the wound dressing under the vacuum. The vacuum chamber may have a vacuum and a power source. The canister further includes a hydrophobic membrane separating the first fluid chamber and the second vacuum chamber. The hydrophobic membrane is dimensioned to span a major portion of the cross-sectional area of the canister. The hydrophobic membrane may be dimensioned to substantially span an internal dimension of the collection canister. 
         [0009]    The hydrophobic membrane may include one or more outwardly extending lobes. One of the benefits of these outwardly extending lobes is they may allow for flow in different system attitudes while maintaining the structural integrity of the system. The outwardly extending lobes may be arranged in staggered or symmetrical relation. The hydrophobic membrane may be releasably mountable to the canister, and, may be supported within a divider separating the first vacuum chamber and the second fluid chamber. The divider may include reinforcing ribs for structural support, especially in the areas between the lobes. The divider may constitute a screen or a mesh in the area beneath the hydrophobic membrane to provide additional mechanical support to the membrane. The hydrophobic membrane may be substantially Z-shaped. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein: 
           [0011]      FIG. 1  is a perspective view of a portable wound therapy system; 
           [0012]      FIG. 2A  is a cross-section said view of the collection canister of the portable wound therapy system of  FIG. 1 ; 
           [0013]      FIG. 2B  is a cross-sectional end view of the collection canister of  FIG. 2A ; 
           [0014]      FIG. 2C  is a top view of the collection canister of  FIGS. 2A and 2B  with the cover removed; 
           [0015]      FIG. 3A  is a cross-sectional view of the collection canister of  FIGS. 2A-2C , in an upright position; 
           [0016]      FIGS. 3B-3C  are cross-sectional views illustrating the collection canisters of 
           [0017]      FIGS. 2A-3A  positioned on respective sides of the canister; 
           [0018]      FIG. 4  is top view of a collection canister including an alternate embodiment of a hydrophobic membrane in accordance with an aspect of the present disclosure; 
           [0019]      FIG. 5  is top view of a collection canister including another alternate embodiment of a hydrophobic membrane in accordance with an aspect of the present disclosure; 
           [0020]      FIG. 6  is top view of a collection canister including another embodiment of a hydrophobic membrane in accordance with an aspect of the present disclosure; 
           [0021]      FIG. 7  is top view of another embodiment of a hydrophobic membrane in accordance with an aspect of the present disclosure; and 
           [0022]      FIG. 8  is a cross-sectional side view of the hydrophobic membrane of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The hydrophobic membranes of the disclosure will be discussed in connection with use in a wound therapy system applying subatmospheric pressure for promoting healing of a wound. Although the membranes will be described as relates to a wound therapy system, alternative uses for the membranes are envisioned. The wound therapy system includes a wound dressing and a portable subatmospheric pressure mechanism in fluid communication with the wound dressing. The subatmospheric pressure mechanism applies subatmospheric pressure to the wound to effectively remove wound fluids or exudates captured by the composite wound dressing, and to increase blood flow to the wound bed, thereby enhancing cellular stimulation of epithelial and subcutaneous tissue. The wound therapy system may be entirely portable, i.e., it may be worn or carried by the subject such that the subject may be completely ambulatory during the therapy period. The wound therapy system may be entirely disposable after a predetermined period of use or may be individually disposable whereby some of the components are reused for a subsequent therapy application. 
         [0024]    Referring initially to  FIG. 1 , wound therapy system  100  is illustrated. Wound therapy system  100  includes composite wound dressing  102  and subatmospheric pressure mechanism or collection canister  104  in fluid communication with the wound dressing  102  through a conduit, identified schematically as reference character “c”. For a more detailed description of wound dressing  102 , including the composition and operation thereof, please refer to commonly assigned U.S. patent application Ser. No. 11/825,480, filed Jul. 6, 2007, the contents of which are incorporated herein by reference in their entirety. 
         [0025]    With reference now to  FIGS. 2A-2C , the structure and operation of collection canister  104  will be described as it relates to the wound therapy system  100 . Canister  104  includes housing  106  defining first chamber  106   a  and second chamber  106   b.  Housing  106  may be rigid, or, in the alternative, comprise a flexible material. First chamber  106   a  includes vacuum source  150  and power source  160 . Vacuum source  150  may be any suitable vacuum pump adapted to present negative pressure either continuously or intermittently within wound dressing  102 . Vacuum source  150  may be associated with computer logic, software or processing means to control operation of therapy system  100 . 
         [0026]    Second chamber  106   b  of canister  104  defines a fluid receiving cavity for receiving exudates and/or fluid “F” from wound dressing  102  ( FIG. 1 ). First and second chambers  106   a,    106   b  are separated by divider  108 . Divider  108  includes hydrophobic membrane  110  adapted to prevent aspiration of fluid “F” collected in second chamber  106   b  into vacuum source  150 . Container  104  further includes cover  107  positioned to seal second chamber  106   a.  Conduit “c” extends through cover  107  and divider  108  and terminates adjacent an upper area or section of canister  104 . 
         [0027]    With continued reference to  FIGS. 2A-2C , divider  108  includes opening  108   a  for receiving conduit “c” therethrough, and rectangular opening  108   b  for at least partially receiving hydrophobic membrane  110 . Although a rectangular opening  108   b  is depicted, other shapes for hydrophobic membrane  110  and opening  108   b  are envisioned. Opening  108   a  may define the outlet of vacuum source  150  which draws a vacuum within second chamber  106   b.  Although the rectangular opening is  108   b  implies a hole or void, this opening may consist of a screen, mesh, or grill to provide structural support to the hydrophobic membrane  110  while still allowing air flow through the membrane. 
         [0028]    Hydrophobic membrane  110  spans a substantially large surface area or cross-section of canister  104  relative to conventional filters which typically cover a small opening adjacent the vacuum pump. Accordingly, as depicted in  FIGS. 3B-3C , when canister  104  is tilted or placed on one of its sides  115 , unless the canister  104  is substantially full with fluids “F” or exudates, at least a portion of hydrophobic membrane  110  will remain free of fluid thereby permitting continued vacuum draw through hydrophobic membrane  110 , divider  108  and within canister  104 . Thus, the relatively large surface area of hydrophobic membrane  110  enables continued use of system  100  even when canister  104  is positioned on its side  115  or tilted. In one aspect, hydrophobic membrane  110  encompasses at least seventy-five (75%) percent of the cross-section of canister  104  and has a length and width closely approximating the respective length and width of “L 1 , W 1 ”. In one embodiment, hydrophobic membrane  110  defines a length “L 1 ” and a width “W 1 ” ranging from about 65%-90% the respective length “L 0 ” and width “W 0 ” of canister  104 . 
         [0029]    Once hydrophobic membrane  110  is completely covered by fluid “F”, in the event second chamber  106   b  is near capacity and canister  104  is placed on either side  115 , or when second chamber  106   b  is completely full, vacuum source  150  may no longer draw air through hydrophobic membrane  110 . Once air can no longer be drawn through hydrophobic membrane  110 , the suction drawing fluid “F” from wound dressing  102  is ceased and fluids “F” are no longer drawn into second chamber  106   b.  Canister  104  then may be emptied or replaced, and therapy may be continued. 
         [0030]    With reference now to  FIGS. 4-6 , other embodiments of collection canisters including hydrophobic membranes according to the present disclosure will now be described and are shown generally as hydrophobic membranes  210 ,  310 ,  410 . Each of hydrophobic membranes  210 ,  310 ,  410  is configured to maximize the effective working area of the membrane to maintain the vacuum draw during manipulation or transfer of the ambulatory system. Each of hydrophobic membranes  210 ,  310 ,  410  is securely received within, or mounted to, divider  108 . 
         [0031]    Referring initially to  FIG. 4 , hydrophobic membrane  210  defines a substantially rectangular body  210   a  including opposing first and second lobes  211   a,    211   b  extending outwardly along a length thereof. For example, hydrophobic membrane  210  may define a substantially Z-shaped member. Divider  108  may have a corresponding inner wall defining a complementary Z-shaped opening  220  (shown in phantom) for at least partially accommodating hydrophobic membrane  210 . Opening  220  follows the contour of the periphery of hydrophobic membrane  210 . Although the opening  220  implies a hole or void, this opening may consist of a screen, mesh, or grill to provide structural support to the hydrophobic membrane  210  while still allowing air flow through the membrane  210 . 
         [0032]    Hydrophobic membrane  210  is adapted to permit air flow when canister  104  is in an upright position, tilted position or on either side  115 . In particular, the positioning of lobes  211   a,    211   b  in opposed relation both vertically and horizontally with respect to  FIG. 4  increases the possibility that one of the lobes  211   a,    211   b  will be free of, or not covered by, liquid when canister  104  is tilted or placed on its side thereby permitting continued vacuum draw within canister  104 . Lobes  211   a,    211   b  may be dimensioned to extend substantially to side wall  115  of canister  104  to maximize the effective operating area of hydrophobic membrane  210 . 
         [0033]    Referring now to  FIG. 5 , this embodiment of hydrophobic membrane  310  includes a body  310   a  having multiple outwardly extending lobes  311   a,    311   b,    311   c,    311   d  staggered along the length “L”. Hydrophobic membrane  310  may include any number of lobes  311   a,    311   b,    311   c,    311   d.  As with lobes  211   a,    211   b,  lobes  311   a,    311   b,    311   c,    311   d  permit air to flow through hydrophobic membrane  310  when canister  104  is in an upright or tilted position. The additional lobes  311   a,    311   b,    311   c,    311   d  along the length of rectangular body  310   a  may enhance vacuum flow through hydrophobic membrane  310 . Divider  108  may include a correspondingly shaped opening  320  (shown in phantom) for receiving membrane  310 . It is envisioned that divider  108  may include ribbing or other structural support between lobes  311   a,    311   b,    311   c,    311   b  to reinforce hydrophobic membrane  310  and/or to add structural integrity to canister  104 . 
         [0034]    With reference now to  FIG. 6 , another embodiment of hydrophobic membrane  410  is illustrated. Hydrophobic membrane  410  includes a body  410   a  having multiple opposing lobes  411   a,    411   b,    411   c,    411   d  extending outwardly along a length thereof. Hydrophobic membrane  410  further includes lobe  412  which extends to end wall  117  of canister  104 . As with hydrophobic membranes  210 ,  310 , lobes  411   a,    411   b,    411   c,    411   d  permit air to flow through hydrophobic membrane  410  when canister  104  is in an upright position, tilted position or positioned on one of its sides  115 . In addition, lobe  412  further permits air to flow through hydrophobic membrane  410  if canister  104  is positioned on opposed end wall  118 . In particular, when canister  104  is positioned on end wall  118 , a volume of air will be present adjacent end wall  117  (provided canister  104  is not full with fluids “F”) to permit continued vacuum draw through lobe  412  and into second chamber  106   b  of canister  104 . 
         [0035]    Referring now to  FIGS. 7 and 8 , another alternate embodiment of according to the present disclosure is illustrated. Filter assembly  510  is independent of canister  104  ( FIG. 1 ) and may be releasably mounted within canister  104  by conventional means. Filter assembly  510  may be disposed after use if desired and replaced with a new filter assembly  510  which may be mounted within canister  104 . Filter assembly  510  includes base  502  and filter element  512  within the base  502 . Base  502  defines a substantially planar member configured to be received in a fluid collection canister (not shown). Base  502  may be adapted for selective attachment with or permanently fixed to the collection canister  104 . Filter membrane  512  defines a substantially rectangular area and possesses multiple opposing lobes  511   a,    511   b,    511   c,    511   d,    511   e,    511   f  extending outwardly along a length thereof. Additional lobes  516  (shown in phantom) may be provided adjacent the end of filter membrane  512 . Base  502  may further include lateral and longitudinal supports  514 ,  515  extending across the width and length of hydrophobic membrane  510 , respectively. Filter membrane  512  functions in a similar manner to the filter membranes described in connection with the prior embodiments by increasing the overall effective operable area of the filter to permit vacuum draw in the event of tipping or inversion of canister  104 . 
         [0036]    Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure.