Abstract:
The present invention provides a device for wound treatment, comprising a chamber that includes an inner surface and defines a treatment space, the chamber being made of a flexible, impermeable material. The device further includes a plurality of structures configured to exert mechanical stress on a wound, the plurality of structures intruding from the inner surface of the chamber into the treatment space. The device further includes a tube having a first end connected to the chamber, the tube being in fluid communication with the treatment space so as to enable at least one selected from the group of applying negative pressure to the treatment space and applying a therapeutic agent.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/601,394 filed on Nov. 23, 2009, which is a 371 of PCT International Application No. PCT/US2008/064897 filed May 27, 2008, which claims the benefit of U.S. Provisional Patent Application 60/931,559 filed May 24, 2007, each of which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       FIELD OF THE INVENTION 
       [0003]    The invention relates generally to the field of wound treatment, and more particularly, to a device for treating wounds with negative pressure and/or therapeutic agents. 
       BACKGROUND OF THE INVENTION 
       [0004]    Many wounds can be treated by the application of negative pressure. The method of such treatment has been practiced for many years. The benefits of such treatment can include: reduction of edema; reduction of wound exudate; reduction of wound size; and stimulation of formation of granulation tissue. Existing devices and appliances for the provision of negative pressure wound therapy are complex. Such devices typically encompass a porous insert such as foam or gauze that is placed into the wound; a tube connecting the insert to a source of suction; a flexible cover draped over these components and sealed to the skin around the wound; an electrically powered suction pump; controls to operate the pump and monitor the system; containers to collect wound fluids; filters to process the materials removed from the wound; and safety systems to prevent harm to the patient and to block the escape of biological materials into the outside environment. These devices are expensive, labor intensive, and restrictive of patient mobility. The many components, particularly the seals around the insert and the tube, tend to leak. Therefore, suction must be applied either continuously or frequently. 
         [0005]    Continuous suction is typically achieved by a vacuum pump powered by an electric motor. Such systems require complex means to measure, monitor, and control the operation of the pump to ensure the safety of the patient. In addition, many negative pressure devices are contraindicated in the presence of necrotic tissue, invasive infection, active bleeding, and exposed blood vessels. They require the use of a porous insert (sponge, foam, gauze, mesh, etc.) in the wound. The insert may present two problems: growth of tissue into the insert, and the harboring of infectious and/or undesirable materials in the insert. Wound tissue can grow into and around such inserts, thereby causing adverse results to the healing process. Moreover, such inserts can retain wound fluid and microorganisms, and therefore can become contaminated and/or infected, presenting an adverse effect to the healing process. In addition, the high cost of these devices may deter or delay their use on patients. 
         [0006]    Existing negative pressure treatment devices are labor intensive since they require the user to assemble, fit, and customize a number of components. First, the user must prepare, trim, and size an insert of foam, gauze, mesh, or other material that will be placed in the wound. Next, the user must position a tube in the insert, and then cover the tube and insert with a material that is intended to create a leakproof seal. In practice, and as mentioned above, such compositions tend to leak, requiring the frequent application of suction in order to establish and re-establish negative pressure within the space about the wound. In addition, currently available negative pressure devices and systems block the view of the wound, making monitoring and diagnosis more difficult. Therefore, an improved device for applying negative pressure to wounds is needed. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In one aspect, the present invention is summarized as a device for wound treatment, comprising a chamber that includes an inner surface and defines a treatment space, the chamber being made of a flexible, impermeable material. The device further includes a plurality of structures configured to exert mechanical stress on a wound and configured to create pathways through which negative pressure can be distributed and maintained in the treatment space, the plurality of structures intruding from the inner surface of the chamber into the treatment space. The device further includes a tube having a first end connected to the chamber, the tube being in fluid communication with the treatment space so as to enable at least one selected from the group of applying negative pressure to the treatment space and applying a therapeutic agent. 
         [0008]    In some embodiments, the plurality of structures and the chamber are part of a single ply of material. In addition, in some embodiments, each of the structures in the plurality of structures is semi-rigid. 
         [0009]    In some embodiments, the device includes a wedge-shaped manual pump, and the treatment space is in fluid communication with the wedge-shaped manual pump. The wedge-shaped manual pump may include a spring that biases the wedge-shaped manual pump to an uncompressed position. 
         [0010]    The foregoing and other objects and advantages of the invention will appear in the detailed description that follows. In the description, reference is made to the accompanying drawings that illustrate a preferred embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The invention may be understood by reference to the following description taken in conjunction with the accompanying figures, in which like reference numerals identify like elements. It should be understood that figures represent an example of the present invention and components are not necessarily shown to be proportional to one another. The terms “chamber wall” or “wall” mean any part of the chamber device that forms or encloses the chamber treatment space. The term “overview” means a view from the inside of the chamber treatment space looking toward the interior surface of the chamber wall. 
           [0012]      FIG. 1  is a perspective view of a wound chamber treatment device with a tube leading from a chamber to a suction source; 
           [0013]      FIG. 2  is a side sectional view of the device in  FIG. 1 ; 
           [0014]      FIG. 3  is a sectional view of the device in  FIG. 1  with an additional tube leading to a port; 
           [0015]      FIG. 4  is a sectional view of the device in  FIG. 1  with a branching tube leading to a port; 
           [0016]      FIG. 5  is a perspective view of the end of the tube communicating with the interior chamber space; 
           [0017]      FIG. 6  is a side sectional view of structures engineered on and into the interior surface of the chamber wall, where the structures are of uniform size and shape, and are spaced uniformly apart; 
           [0018]      FIG. 7  is a side sectional view of two groups of structures engineered on and into the interior surface of the chamber wall, where one group intrudes into the chamber space, the other group intrudes to a lesser extent, and structures from these groups alternate in a regular pattern; 
           [0019]      FIG. 8  is a side sectional view of three groups of structures engineered on and into the interior surface of the chamber wall, where such groups have varying degrees of intrusion into the chamber space and alternate in a regular pattern; 
           [0020]      FIG. 9  is an overview of structures engineered on and into the interior surface of the chamber wall, where the structures consist of raised ridges; 
           [0021]      FIG. 9   a  is a side sectional view of the raised ridges of  FIG. 9  with rounded edges; 
           [0022]      FIG. 9   b  is a side sectional view of the raised ridges of  FIG. 9   a  with square cross sections; 
           [0023]      FIG. 10  is an overview of the raised ridge structures shown in  FIG. 9 , with the addition of raised dome structures positioned among the ridges; 
           [0024]      FIG. 11  is an overview of raised ridge structures engineered on and into the interior surface of the chamber wall, where two parallel lines of such structures form a channel; 
           [0025]      FIG. 12  is an overview of raised dome structures engineered on and into the interior surface of the chamber wall, where two parallel lines of such structures form a channel; 
           [0026]      FIG. 13  is a view of a wound chamber, showing a pattern of channels leading to the center of the chamber and then to the tube communicating from the interior of the chamber space; 
           [0027]      FIG. 14  is a view of a radiating pattern of channels leading to the communicating tube; 
           [0028]      FIG. 15  is a view of a branching pattern of channels leading to the communicating tube; 
           [0029]      FIG. 16  is a view of a sub-branching pattern of channels leading to the communicating tube; 
           [0030]      FIG. 17  is a side sectional view of a fold in the chamber wall; 
           [0031]      FIG. 18  is a side sectional view of a fold in the chamber wall, with structures engineered on and into the inner surface of the fold, which structures maintain continuous open space within the fold; 
           [0032]      FIG. 18   a  is a side sectional view of the fold in the chamber wall of  FIG. 17  with structures engineered on the inner surface of the fold; 
           [0033]      FIG. 19  is a view of a wound chamber configured as a tube for placement over a limb, and having engineered structures and channels on the interior surface of the chamber wall; 
           [0034]      FIG. 20  is a sectional view of the device in  FIG. 1  showing a fluid collector placed before the suction source; 
           [0035]      FIG. 21  is a sectional view of a suction device in the form of a squeeze bulb of deformable material; 
           [0036]      FIG. 22  is a sectional view of a suction device in the form of a flexible chamber containing one or more compression springs; 
           [0037]      FIG. 23  is a sectional view of a suction device in the form of a wedge-shaped chamber containing one or more torsional springs; 
           [0038]      FIG. 24  is a sectional view of the device in  FIG. 23  containing a flat spring; and 
           [0039]      FIG. 25  is a sectional view of a suction device with a trap and filter incorporated into the exhaust port. 
       
    
    
       [0040]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are described below in detail. It should be understood, however, that the description of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0041]    While the present invention may be embodied in any of several different forms, the present invention is described here with the understanding that the present disclosure is to be considered as setting forth an exemplification of the present invention that is not intended to limit the invention to the specific embodiment(s) illustrated. 
         [0042]    The present invention is directed to providing a simple, safe, disposable, and cost-effective device that is easy to install and operate, that allows freedom of motion to the patient, and that overcomes, or at least reduces the effects of, one or more of the problems set forth above. The present invention does not require the use of a porous insert. The one-piece construction of the device eliminates virtually all leaks, therefore preserving and maintaining negative pressure within the wound without the need for constant or frequent regeneration of negative pressure. In addition, the structure of the device is configured to promote wound healing and to create pathways through which negative pressure can be distributed and maintained in the treatment space. The indications for the present invention may be expanded beyond the limitations imposed on current devices. The cost-effectiveness of the present invention may lead to the provision of negative pressure wound therapy on a more widespread basis and earlier in the timeline of wound care. 
         [0043]    One aspect of the present invention is seen in a wound treatment device including a chamber defining a treatment space around the wound. The flexible adhesive base of the chamber forms a water-tight and gas-tight seal. A tube communicates from the treatment space to a source of suction. The suction source also serves as a receptacle for materials removed from the chamber. All components preferably are inexpensive, lightweight, and disposable. 
         [0044]    Referring first to  FIGS. 1 and 2 , views of a wound treatment device  20  are provided. The device  20  includes a chamber  22  defining a treatment space  24  and a base  26  that may be sealed to a skin surface  28  of a patient over a wound  30 . In the illustrated embodiment, the chamber  22  has a bellows configuration with a fold  23 . However, the invention is not so limited, and other configurations of a chamber formed of a flexible, moisture and gas impermeable material may be used. Materials from which the device  20  may be made will be discussed in further detail below. The device  20  can be designed for use with any wound or body part, using circular, square, rectangular, tubular, pouch, envelope or other shapes. For example, a chamber in the form of a tube or sleeve for placement over a limb is shown in  FIG. 19 . Referring again to  FIGS. 1 and 2 , a dermal or cutaneous adhesive material may be provided on a bottom surface of the base  26  for providing a fluid-tight seal with sufficient adhesive strength to prevent inadvertent removal of the chamber  22  or breach of the fluid-tight seal during normal patient movement. Numerous adhesive materials sufficient for these purposes are known to those of ordinary skill in the art. 
         [0045]    A tube  32  is attached to the chamber  22  preferably at a location spaced above the base  26  and communicates with the treatment space  24 . The tube  32  is constructed to maintain its shape without collapsing and to permit the passage of wound fluids and wound debris. The tube  32  may be permanently fixed to the chamber  22 , or a fitting  25  may be provided to allow the attachment and removal of the tube  32  or any other device that can deliver material or therapies to, or remove material from, the treatment space  24 . The tube  32  may terminate at a wall of the chamber  22 , or it may extend through the wall a distance and terminate within the treatment space  24 , where it may communicate with such space, with channels formed on the inner surface of the chamber wall, or with folds formed in the chamber wall. The tube  32  is sealed to the chamber  22  in such a manner as to prevent the escape of liquid or gas from the treatment space  24  to the outside environment. A distal end of the tube  32  terminates at a suction device  34 . The suction device  34  may be a pump, although other types of devices may be used as discussed below. A fitting  33  may be provided to permit the detachment and reattachment of a suction device  34  to the tube  32 . 
         [0046]    Turning to  FIG. 3 , a sectional view of the device  20  is provided, showing a second tube  35  attached to the chamber  22  and communicating with the treatment space  24 , with channels, or with folds. A distal end of the tube  35  terminates in a portal  36 . The invention is not limited to any number of communicating tubes, and multiple tubes and portals may be provided for accessing the treatment space  24 .  FIG. 4  shows the device in  FIG. 1  with a branch of the tube  32  that leads to a portal  36 . The portal  36  may be used for the delivery of therapeutic agents—such as antimicrobials, antibiotics, antifungals, and analgesics—prior to, during, or after the delivery of negative pressure. As such, the portal  36  may be a lure configured for attaching to a container or a syringe. Alternatively, therapeutic agents may be delivered through the same tube  32  that communicates with the suction device  34 . 
         [0047]    Turning now to  FIG. 5 , the end of the tube  32  extending into the chamber space  24  is shown with multiple holes [apetures?]  44 . The purpose of the holes  44  is to ensure that gases, liquids, wound fluid, debris, and other materials can flow and move out of the chamber space  24  into the tube  32  without impediment. 
         [0048]    Referring to  FIG. 6 , the interior surfaces of the chamber wall may be configured with structures  40  that are engineered on the surfaces. The portions of the interior surfaces with engineered structures  40  may be varied from that shown in the figures, and preferably a high percentage of the interior surfaces include engineered structures  40 . The structures preferably cover at least 50% of the interior surfaces, and more preferably at least 95% of the interior surfaces. These structures are raised when viewed from within the chamber space  24 , and they intrude into such space in directions generally perpendicular to the interior surfaces of the chamber space  24 . These structures can be any shape, including without limitation a cone, a pyramid, a pentagon, a hexagon, a half sphere, a dome, a rod, an elongated ridge with rounded sides, or an elongated ridge with square sides. The structures can be provided as identical shapes, or in any combination of shapes. The structures can be provided with identical sizes, or in any combination of different sizes. The distance of intrusion into the chamber treatment space  24  from the chamber wall by such structures is preferably between 0.01 mm and 20 mm, and is more preferably between 1 mm and 1 cm. The spacing between such structures is preferably between 0.01 mm and 5 cm. 
         [0049]    The engineered structures  40  interface with the wound surface during use of the device  20 . One purpose of these structures is to ensure that negative pressure established within the chamber space  24  is evenly distributed and maintained throughout such space. As negative pressure is established within the tube that leads to the source of suction, the chamber will lie tighter against the wound tissue. The device  20  includes the engineered surfaces  40  in order to define pathways to establish, distribute, and maintain negative pressure across the wound surface and prevent complete contact between the inner surfaces of the chamber and the wound tissue. Without such structures, the chamber wall would make complete contact with the wound surface. As a result, there would be no space within which negative pressure could be established, distributed, and maintained. Therefore, the engineered structures are preferably semi-rigid. The term “semi-rigid” should be understood as meaning that deformation only occurs at a microscopic level under operating negative pressures in the range of 0.5-2 psi. Alternatively, the engineered structures may be somewhat flexible depending on the spacing between the structures. In addition, the structures are engineered to reduce the extent to which wound tissue can enter the space between the structures, so that a sufficient amount of open space is maintained. 
         [0050]    An additional purpose of these structures is to serve as a form of stimulation to the wound to produce beneficial results, including without limitation the formation of granulation tissue and an increase of micromechanical forces. Such mechanical forces provide stimulation to a portion of the wound tissue, which has been suggested as a contributing factor to the effectiveness of negative pressure wound therapy. From the above discussion and the figures, it should be understood that the flexible chamber is movable over a range of positions. The range of positions includes a first position, such as the position shown in  FIGS. 1 and 2 , in which the engineered structures  40  are spaced apart from the opening of the chamber defined by the base  26 . The range of positions also includes a second position in which at least some of the engineered structures  40  are positioned in the opening of the chamber. The second position is preferably a position in which the engineered structures  40  engage the wound. 
         [0051]    The chamber wall can be formed of any appropriate medical grade material that has the following characteristics: flexibility, conformability, gas impermeability, liquid impermeability, the ability to be formed, tooled, and engineered, and the ability to retain the shape, function, and effectiveness of raised structures under desired ranges of negative pressure. In addition, the material is preferably hypo-allergenic and provided to a medical facility in a sterile condition. For example, the chamber device may be made of a flexible, conformable material such as polyurethane, although other similar materials may also be used. The chamber is preferably designed to provide sufficient material to lie against the surface of the wound tissue without special sizing, trimming, or other customizing operations. The chamber may be made from a single ply of material, or may be constructed of multiple layers of material in and on which the structures are engineered. It should be understood that a single ply chamber may be made of multiple sheets of material during manufacturing, but is provided to a medical facility in a state in which the multiple sheets are bonded or otherwise connected to one another. For example, individual three dimensional shapes may be adhered or bonded to the inner surface of the chamber wall during manufacturing to provide the engineered structures. A single ply chamber could also be formed from a single sheet of material that defines both the chamber walls and the engineered structures. Alternatively, a multiple layer chamber is provided to a medical facility in a state in which layers of material are stacked to form the chamber. For example, the layer facing the interior treatment space of the chamber could be a layer containing engineered structures that is bonded onto a generally flat layer of material (or multiple sheets of generally flat layers) by a medical practitioner. 
         [0052]    The engineered structures can be made by techniques familiar to those in the art, such as embossing, stamping, molding, forming, or bonding. If the structures are created by embossing their shape into the material, the embossed structures may be left in a concave state relative to the outside of the chamber as shown in  FIG. 6 . Embossed structures may also be formed on a single ply of material that also forms the walls of the chamber and the base. This may provide a chamber that is relatively flexible and semi-rigid structures on a single ply of material. Alternatively, the cavities may be filled with a suitable material to render the structures solid. As another alternative, solid structures can be affixed to the inner surfaces of the chamber. 
         [0053]    The raised structures on the inner surfaces of the chamber wall can be configured and distributed in a number of patterns. For example,  FIG. 6  is a side sectional view of a portion of a chamber wall, showing engineered structures  40  on the interior surface of the material that faces treatment space  24 . Structures  40  are identical in shape and size, and are positioned uniformly apart from one another. As another example,  FIG. 7  is a side sectional view showing engineered structures  41  and  42  intruding into the chamber space, where structures  41  intrude farther than structures  42 , and the structures are configured in a regular alternating pattern of  41 - 42 - 41 - 42  and so forth. As yet another example,  FIG. 8  is a side sectional view showing engineered structures  43 ,  44 , and  45  intruding into the chamber space, where structures  43  intrude farther than structures  44  and  45 , structures  44  intrude less than structures  43  but farther than structures  45 , and structures  45  intrude less than structures  43  and  44 . These structures are configured in a regular alternating pattern of  43 - 45 - 44 - 45 - 43 - 45 - 44 - 45 - 43  and so forth. The embodiment shown in  FIG. 8  makes it difficult for soft wound tissue to penetrate all of the spaces among the raised structures. A sufficient amount of continuous space is established to make possible the distribution of negative pressure, as well as the addition of fluids and therapies and the removal of fluids and materials from the wound. As yet another example,  FIG. 9  is an overview of a portion of the chamber wall, showing engineered structures  47  in the form of raised ridges. The engineered structures  47  may be rounded ( FIG. 9   a ), square ( FIG. 9   b ), or a combination thereof when viewed from the side. As yet another example,  FIG. 10  is an overview showing engineered dome structures  48  interspersed with ridge structures  47 . The engineered dome structures  48  are preferably semi-spherical when viewed from the side, although other shapes are contemplated. 
         [0054]    The distribution and maintenance of negative pressure within the chamber device and at all points on the wound may be enhanced by providing defined channel spaces as pathways among the raised engineered structures for the distribution of negative pressure. However, defined channel spaces are not required for providing fluid pathways within the treatment space.  FIG. 11  is an overview of a portion of the chamber wall, showing structures  47  arranged in two parallel lines to form channel  49 .  FIG. 12  shows a channel  49  formed by two parallel lines of raised domed structures  48 . Such channels can be configured in various patterns, such as radial, circular, concentric, or branching.  FIGS. 13-16  show overviews of patterns of channels  49  leading from tube  32  along the interior surface of chamber  22  facing treatment space  24 . For each pattern, the channel  49  defines a space that opens directly to the treatment space  24 . The space preferably opens to the treatment space  24  over the entire length of the channel  49 . 
         [0055]    The distribution and maintenance of negative pressure with the chamber device and at all points on the wound can also be enhanced by the use of folds in the chamber wall to create additional channel space for the distribution of negative pressure. When negative pressure is established within the chamber, the material will tend to fold along the pre-formed location.  FIG. 17  shows a channel  50  formed in a fold of the chamber wall. The channel  50  defines a space that opens directly to the treatment space  24 . The space preferably opens to the treatment space  24  over the entire length of the channel  50 . In order to increase the amount of channel space within such fold, the walls of the fold can be configured with structures that prevent the collapse of such space, and ensure continuous open space for the distribution and maintenance of negative pressure, and the passage of liquid, gas, and other material. As an alternative,  FIG. 18  shows engineered structures  52  that prevent the total collapse of the fold, and ensure continuous channel space  51 . All channel spaces created on the interior surface of the chamber wall or by means of folds function as means to increase the effectiveness of distributing and maintaining negative pressure within the chamber, and also as means to enhance the effectiveness of removing gas, liquid, wound fluid, debris, and other materials from the chamber treatment space. As another alternative,  FIG. 18   a  shows an embodiment similar to the embodiment shown in  FIG. 17  with the addition of engineered raised structures  52  on opposite sides of the fold. The engineered structures  52  are provided so that the fold will not collapse to the point where all of its interior surfaces form a tight seal against the movement of negative pressure. However, some of the interior surfaces, such as those adjacent to the fold, preferably contact the wound to provide stimulation as discussed above. The folds described in the previous embodiments are preferably formed at certain defined areas by molding or embossing the surfaces of the chamber  22 . 
         [0056]      FIG. 19  shows a wound chamber device  120  for delivering negative pressure and therapeutic substances in the form of a tube that can be placed over a limb. The wound chamber device  120  is generally cylindrical and includes an open end and a closed end. The open end is preferably sealed with a cuff or collar (not shown), and the open end may include adhesive on the interior surface. The wound chamber device  120  includes engineered structures  40  and channels  49  on the interior surface of the chamber wall. 
         [0057]    As shown in  FIG. 20 , a fluid collector  60  may be positioned on the tube  32  between the chamber  22  and the suction device  34 . The collector  60  is intended to receive fluid extracted from the chamber space  24  and debris or material from the wound and store such materials for eventual disposal. The collector  60  may be detachable from the tube  32 , in order to replace a full collector with an empty collector. 
         [0058]    Suction for the wound treatment device is provided by a suction device  34 , which may be a pump that is connected and disconnected to the chamber device by appropriate connectors. Although the wound chamber can be used with a motor driven pump, it is also effective with a hand-powered device actuated by the caregiver or patient. The hand-powered device may be a squeeze bulb that provides suction by means of the energy stored in the material of its construction. Alternatively, the suction device may be powered by springs that are compressed by the user. The springs can be selected to produce the clinically desired level of negative pressure. The amount of suction provided by these suction devices is therefore dependent on the level of force generated by squeezed material or the springs. Unlike a motor driven suction pump, the hand powered device preferably cannot produce a high level of suction that may cause an adverse effect to wound healing. 
         [0059]    Referring to  FIG. 21 , a suction device  61  in the form of a bulb constructed of a deformable material that stores the energy of deformation may be used. The tube  32  communicates with the interior of the suction device  61 . A one-way exhaust valve  62  also communicates with the interior of the suction device  61 . When the user squeezes the suction device  61 , air within the device is expelled through the exhaust valve  62 . A portion of the energy used to deform the suction device  61  is stored in the material of which it is constructed, thus maintaining suction within the device, as well as within the tube  32  and the chamber space  24 . The bulb is selected and engineered to maintain a constant force and to maintain the clinically desired level of negative pressure within chamber space  24 . Fluid from the wound  30  can flow through the tube  32  into the suction device  61  where it can be stored prior to disposal. Once the suction device is full of fluid, the production of negative pressure ceases. The fluid capacity of the suction device thus operates as a safety shut-off mechanism without the need for electronic sensors and controls. 
         [0060]      FIG. 22  shows an alternative suction device  63 , consisting of flexible sides  64  and rigid sides  65 . Compression springs  66  are located within suction device  63 . The tube  32  and the exhaust valve  62  both communicate with the interior of the suction device  63 . When the user squeezes the rigid sides  65  towards one another, the springs  66  are compressed and air within the device is expelled through a one-way exhaust valve  62  thus maintaining suction within the device, as well as within the tube  32  and the chamber space  24 . The springs  66  are selected and engineered to maintain a constant force against rigid sides  65 , and to maintain the clinically desired level of negative pressure within chamber space  24 . Fluid from the wound  30  can flow through the tube  32  into the suction device  63  where it can be stored prior to disposal of the entire device  63 . This suction device will also cease operating when it is filled with fluid. 
         [0061]      FIG. 23  shows an alternative suction device  70 , consisting of rigid sides  72 , joined by hinge  73 , and flexible side  71 . A torsional spring  74  is attached to either the interior or the exterior of rigid sides  72 . The tube  32  and the exhaust valve  62  both communicate with the interior of the suction device  70 . When the user squeezes the rigid sides  72  towards one another, the spring  74  is compressed and air within the device is expelled through a one-way exhaust valve  62 , thus maintaining negative pressure within the device, as well as within the tube  32  and the chamber space  24 . The spring  74  is selected and made to maintain a force against rigid sides  72  to maintain the clinically desired level of negative pressure within chamber space  24 . Fluid from the wound  30  can flow through the tube  32  into the suction device  70  where it can be stored prior to disposal of the entire device.  FIG. 24  shows the device of  FIG. 27  where the torsional spring  74  has been replaced by a flat spring  78 . 
         [0062]    For the previous suction devices, once suction has been established, fluid may flow from the wound to the suction device, where it may be collected and stored for eventual disposal. Alternatively, a separate fluid collector, such as the fluid collector  60  in  FIG. 20 , can be positioned between the chamber and the suction device. Once the suction device has expanded to its original shape, suction ceases. The suction device will not continue to operate, and can be disconnected and disposed of. If treatment is to be continued, a new suction device can be connected and activated. 
         [0063]      FIG. 25  is a sectional view of a trap  80  and a filter  82  interposed between the suction device  34  and the exhaust valve  62  for the purpose of preventing the expulsion of liquids or aerosols from the suction device. 
         [0064]    The present invention can be engineered to operate at various levels of negative pressure, in accordance with clinical procedures. Historically, the commonly accepted range of negative pressure is between 0.5 and 2 psi. The device of the present invention operates efficiently in this range. The chamber material conforms to the shape of the wound, and the embossed projections maintain their shape and functionality. However, the chamber can be engineered to operate at higher levels of negative pressure. In addition, if a hand-powered suction device is used, the operating pressure of the device may be higher than the commonly accepted range; that is, the device may operate at a pressure close to 0 psi before suction ceases. 
         [0065]    The effectiveness of the raised structures in distributing and maintaining negative pressure within the chamber and across the wound surface has been demonstrated in a test model. A wound was created in a sample of animal cadaver tissue. A pressure sensor was installed in the tissue at the center of the wound. A wound chamber device with raised engineered structures on the interior chamber wall was sealed to the skin around the wound. A tube from the chamber device was connected to a source of suction capable of delivering a range of negative pressure. The amount of negative pressure measured at the suction source was compared to the measurement at the center of the wound, in order to determine the effectiveness of the device with respect to the distribution of negative pressure to the wound. The following values were obtained: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Pressure at Source (mmHg) 
                 Pressure in Wound (mmHg) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 −80 
                 −65 (81.25% efficiency) 
               
               
                   
                 −100 
                 −86 (86.00% efficiency) 
               
               
                   
                 −120 
                 −100 (83.33% efficiency)  
               
               
                   
                   
               
             
          
         
       
     
         [0066]    The raised structures were observed to maintain their shape with no deformation, thereby preserving their functionality. 
         [0067]    The operation of the invention may be illustrated by the following case. A patient with a full-thickness skin wound was treated with a wound chamber negative pressure device connected to a hand-powered suction pump. The interior surface of the chamber contained embossed raised structures. The area around the wound was treated with normal skin disinfectants. The backing from the adhesive base of the chamber was removed, and the chamber was sealed to the normal skin around the wound. The tube was connected to a modified squeeze bulb with an inlet port for fluid, and an exhaust port through which air can be expelled from the bulb. By squeezing the bulb down to its flattest configuration, a negative pressure of 2 pounds per square inch was established and maintained within the chamber. After the first twenty-four hours of treatment, the squeeze bulb had expanded to approximately half of its normal size. The bulb was compressed again to its fully flattened configuration. The bulb remained in such configuration for an additional twelve hours, at which point the chamber was removed. The wound showed healthy granulation tissue and progressed to heal rapidly and with minimal scarring. The device produced no adverse effects on the wound or the surrounding skin. 
         [0068]    The present invention eliminates many of the drawbacks to existing negative pressure wound therapy systems. For example, the device of the present invention is preferably simplified and lightweight. In some embodiments of the invention, the patient is not restricted to a source of electricity or a battery pack. The system can be worn with ease, so that the patient&#39;s mobility is not otherwise compromised. In addition, the wound interface appliance can be applied quickly without the need for custom fitting and construction. The device preferably does not leak due to the smooth adhesive base, eliminating the need for constant suction from an electric pump with sophisticated controls and safety measure. There is no porous wound insert that can potentially cause tissue in-growth and harbor infectious material. Instead, the inner surfaces of the chamber are generally non-porous and non-adherent to prevent any interaction with the wound tissue. Further still, the suction pump preferably has built-in safety limitations on force of suction, duration of operation, and overfilling of the collector for wound fluid. 
         [0069]    The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.