Abstract:
A wound therapy and tissue management system utilizes fluid differentiation. Fluid is differentiated by establishing a gradient within the system. The gradient can be established with matter or energy. Patient interfaces for establishing, maintaining and varying one or more gradients include transfer elements with first and second zones having different flow coefficients. The transfer elements exchange fluid with a patient, generally through a wound site, and with external components of the system. Osmolar solution gradients are controlled by a methodology involving the present invention for extracting solutions, which can include toxins, from patients and for introducing fluids and sumping air to wound sites.

Description:
CROSS-REFERENCE TO RELATED APPLICATION AND PRIORITY CLAIM  
       [0001]    The present application is based on and claims priority in U.S. Provisional Patent Application Serial No. 60/287,323; filed Apr. 30, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to medical care, and in particular to wound therapy and tissue management systems and methodologies with fluid differentiation.  
           [0004]    2. Description of the Prior Art  
           [0005]    Heretofore, many wound therapy and tissue management devices and protocols have tended to focus on the addition or control of individual mechanical forces and their respective effects on wound healing. For example, the use of suction to secure skin graft dressings in place is disclosed in Johnson, F. E.,  An Improved Technique for Skin Graft Placement Using a Suction Drain;  Surgery, Gynecology and Obstetrics 1984; 159 (6): 584-5. Other prior art devices have focused on the application of compressive (i.e. positive or greater-than-atmospheric) pressure to a wound site, the application of heat and the delivery of pharmacological agents.  
           [0006]    Standard methods in the current practice of wound care require changing dressings to topically add pharmacological agents requiring interval reapplication. Reapplications of pharmacological agents can be minimized or eliminated by using slow-release delivery systems. However, such systems must generally be changed in their entireties in order to change the agents or dosages.  
           [0007]    Another wound treatment protocol option involves dosing the entire patient. Agents are thereby delivered systemically, i.e. from within the patient, as opposed to other protocols which deliver respective agents externally or topically. However, systemic medications are generally administered in relatively high doses in order to provide sufficient concentrations in affected areas and treatment sites. Non-affected tissues and organs remote from the treatment sites thus tend to receive concentrations of medications from which they may not benefit.  
           [0008]    Fluid management significantly affects many aspects of health care and is involved in many medical procedures. For example, wound care typically involves absorbing and/or draining wound exudates, blood, serum and other body fluids from the patient. Surgical procedures often create wounds requiring tissue management and fluid drainage. For example, skin grafts have exudates and bleeding that require management at both the donor and graft sites. However, current tissue management and fluid drainage procedures are often ineffective in maintaining optimum moisture content for promoting wound healing. Excessive drying can lead to desiccation. Excessive moisture, on the other hand, can lead to maceration. Reepithelialization interference, tissue breakdown and necrosis can result therefrom.  
           [0009]    Various types of porous, absorbent dressing materials have been used for dressing wounds to accumulate body fluids. The dressing materials facilitate drainage and also the collection and disposal of fluids. A disadvantage with many conventional dressings is that they require changing in order to reduce the risk of infection and to maintain effectiveness. However, dressing changes can add significantly to treatment costs and are associated with patient discomfort and medical risks such as infection and damage to reepithelialized tissues. Accordingly, vacuum sources have been employed to drain wounds. For example, Zamierowski U.S. Pat. No. 4,969,880; No. 5,100,396; No. 5,261,893; No. 5,527,293 and No. 6,071,267 pertain to wound dressings, fluid connections, fastening systems and medical procedures utilizing same in connection with vacuum-assisted wound drainage, and are incorporated herein by reference.  
           [0010]    A wound drainage device using a hand-operated suction bulb is shown in the George et al. U.S. Pat. No. 4,392,858. Motorized suction pumps can be employed to provide consistent, sub-atmospheric vacuum pressure for maintaining an effective drainage flow. The Richmond et al. U.S. Pat. No. 4,655,754 and No. 4,826,494 disclose vacuum wound drainage systems that can be connected to motorized vacuum pumps.  
           [0011]    Another important objective in designing an effective wound drainage system is to provide an effective interface with the patient. Ideally, the patient interface should accommodate various types of wounds in different stages of recovery for as broad a range of applications as possible. As noted above, optimum wound healing generally involves maintaining a sufficient moisture level to avoid desiccation without causing the wound to macerate from excessive moisture. Sufficient moisture levels are required for epithelial cell migration, but excessive moisture can inhibit drying and maturation of the epithelial layer. Pressures should be sufficient for effective drainage without creating excessive negative forces, which could cause pressure necrosis or separate freshly applied skin grafts.  
           [0012]    Wound treatment procedures can also include diffusing wound sites with liquids to flush contaminants, counter infection, promote healing growth and anesthetize the wound. Prior art fluid delivery systems include a device for treating tissues disclosed in the Svedman U.S. Pat. No. 4,382,441; a product and process for establishing a sterile area of skin disclosed in the Groves U.S. Pat. No. 3,367,332; and the transdermal infusion device disclosed in the Westin U.S. Pat. No. 4,605,399. Equipment has also been available which flushes and collects contaminants from wounds.  
           [0013]    Heretofore, there has not been available a system or methodology that allowed the manipulation of multiple mechanical forces affecting wound surfaces. Moreover, there has not previously been available a system or methodology that manipulated the gradients of gases, solids, liquids and medications in such a way as to provide the medical practitioner with various options for delivering the various agents from either the patient side or externally and topically. Further, there has not been available a system or methodology which affected the removal of toxins and undesirable byproducts by an external egress with the advantages and features of the present invention. Such advantages include minimizing or eliminating dressing changes whereby patient discomfort and infection risks are correspondingly reduced.  
           [0014]    Effective control of fixation, temperature, pressure (and its associated gradients for vital gases such as oxygen), osmotic, isosmotic and oncotic forces, electrical and electromagnetic fields and forces and the addition and/or removal of various nutrients and pharmacological agents have not been achievable with the previous systems and methodologies. Still further, there has not been available a wound treatment system and methodology utilizing a transfer element for the manipulation of gas and liquid pathways under the control of pre-programmed, coordinated influx and efflux cycles. Such cycles are designed to maintain the desired integrity and stability of the system while still allowing variations in multiple forces, flows and concentrations within tolerated ranges. Previous wound treatments also tended to lack the dynamic and interactive features of the present invention whereby various gradients can be adjusted in response to patient wound site conditions. Such gradient adjustments can be accomplished with the present invention through the use of biofeedback loops and patient-responsive sensors.  
           [0015]    Osmolar/osmotic gradients provide an important mechanism for transferring various elements within the scope of the present invention. Such gradients occur naturally in living organisms and involve the movement of solutes from solutions with greater concentrations to solutions with lesser concentrations through semi-permeable membranes. Osmosis is the tendency of solvents to pass through semi-permeable membranes into solutions of higher concentrations in order to achieve osmotic equilibrium. Examples include the osmotic transfer of oxygen from alveoli to capillaries within the lung and the osmotic transfer of toxins and waste within the kidneys to the bladder. The systems and methods of the present invention utilized and control osmolar (osmotic) gradients to advantage in treating wounds, particularly in connection with the removal of toxins in solution from wound sites by controlling fluids. The control fluids originate both internally and externally. For example, wound exudates originate internally. External control fluids include sumped air, irrigation, etc.  
           [0016]    Previous wound treatment systems and methodologies did not provide medical practitioners with the range of options available with the present invention for treating various patient circumstances and conditions.  
         SUMMARY OF THE INVENTION  
         [0017]    In the practice of the present invention, a wound therapy and tissue management system is provided, which includes a collector assembly for attachment to a patient, a transfer assembly connected to the collector assembly and a gradient (e.g., negative pressure/vacuum, positive pressure, temperature, oxygen, etc.) source connected by suction tubing to the transfer assembly. The system is adaptable for use with various dressing assemblies, including multiple layers and components comprising hydrophobic and hydrophilic foam and sponge materials, semi-permeable and impermeable membranes applied as drapes, transfer system conduits and buffers, and tubular connections to pumps. Alternative embodiments of the system utilize osmotic/osmolar gradients for controlling transfers and provide various optional configurations with internal and external inputs, installation ports and other components. In the practice of the method of the present invention, a fluid differentiation wound therapy and tissue management method is disclosed, which includes steps of shaping and applying a first sponge comprising a first sponge material to a wound area, applying a first drape, shaping and applying a second sponge comprising a second sponge material on top of the first drape and the first sponge, forming a fluid conduit and connecting same to the second sponge and to a buffer for ultimate connection to a vacuum pump. The conduit and the buffer are also draped. Osmotic/osmolar wound therapy and tissue management methodologies are also discussed in connection with the present invention. The transfer of fluids and substances such as toxins can be controlled through the application of such methodologies.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a block diagram of a vacuum-fixed wound therapy system embodying the present invention.  
         [0019]    [0019]FIG. 2 is a perspective view of a composite dressing assembly.  
         [0020]    [0020]FIG. 3 is a vertical cross-sectional view of the dressing assembly taken generally along line  3 - 3  in FIG. 2.  
         [0021]    [0021]FIG. 4 is an enlarged, fragmentary, cross-sectional view of a composite dressing comprising a first modified embodiment of the present invention.  
         [0022]    [0022]FIG. 5 is a perspective view of a composite dressing comprising a second modified embodiment of the present invention.  
         [0023]    [0023]FIG. 5 a  is a perspective view of a variation of the embodiment shown in FIG. 5.  
         [0024]    [0024]FIG. 6 is a perspective view of a transfer assembly for a composite dressing comprising a third modified embodiment of the present invention.  
         [0025]    [0025]FIG. 7 is a cross-sectional view of a third modified embodiment composite dressing.  
         [0026]    [0026]FIG. 8 is a perspective view of the third modified embodiment composite dressing.  
         [0027]    [0027]FIG. 9 is a perspective view of a composite dressing comprising a fourth modified embodiment of the present invention.  
         [0028]    [0028]FIG. 10 is a flow diagram of a vacuum-fixed wound therapy method embodying the present invention.  
         [0029]    [0029]FIG. 11 is an exploded view of a wound treatment system with vacuum, heat and fluid assistance.  
         [0030]    [0030]FIG. 12 is an exploded view of another wound treatment system with vacuum, heat and fluid assistance.  
         [0031]    [0031]FIG. 13 is an exploded view of yet another wound treatment system with vacuum, heat and fluid assistance.  
         [0032]    [0032]FIGS. 14 a - d  comprise graphs showing the temperature-elevating performance of the wound treatment systems shown in FIGS.  11 - 13 .  
         [0033]    [0033]FIG. 15 is a block diagram of a wound therapy and tissue management system comprising an eighth alternative embodiment of the present invention.  
         [0034]    [0034]FIG. 16 is a schematic diagram of the eighth alternative embodiment wound therapy and tissue management system.  
         [0035]    [0035]FIG. 17 is a flowchart of a wound and therapy and tissue management methodology embodying the present invention.  
         [0036]    [0036]FIG. 18 is a block diagram of a wound therapy and tissue management system comprising a ninth alternative by the present invention.  
         [0037]    [0037]FIG. 19 is a diagram showing various phases in a hyperosmolar or air-sump system embodying the present invention.  
         [0038]    [0038]FIG. 20 is a diagram showing various phases in an osmolar or isotonic flush or rinse system embodying the present invention.  
         [0039]    [0039]FIG. 21 is a diagram showing a hypo-osmolar or heavy drape system embodying the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    I. Introduction and Environment  
         [0041]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.  
         [0042]    II. Vacuum-Fixed Wound Therapy Dressing  3   
         [0043]    Referring to the drawings in more detail, the reference numeral  2  generally designates a vacuum-fixed wound therapy system for application to a wound  4  on or in a patient  5 . The system  2  includes an improved dressing  3 . Other components of the system  2  are described in my U.S. Pat. No. 6,071,267, which is incorporated herein by reference.  
         [0044]    The dressing  3  generally includes a collector assembly  6  and a transfer assembly  8  connected to a vacuum source  10 . The collector assembly  6  includes a first sponge  12  comprising a hydrophilic material, such as polyvinyl alcohol (PVA). The first sponge  12  is cut to generally conform to the size of the wound  4 . A first sponge drape  14  is placed over the first sponge  12  and an opening  16  is formed in the drape  14  and is preferably sized smaller than the first sponge  12 . The drape  14  encloses a compression chamber  15  containing the first sponge  12 . A dry skin, moisture-control zone  17  is formed around the first sponge  12  due to air circulation within the compression chamber  15  and promotes healing.  
         [0045]    A second sponge  18 , preferably comprising a hydrophobic polyurethane ether (PUE) material is sized larger than the first sponge  12 , whereby a second sponge overhang  20  extends beyond the perimeter of the first sponge  12 . A second sponge drape  22  is placed over the second sponge  18  and includes an opening  24  located along an outer edge  26  of the second sponge  18  for directing the outflow of fluid effluent from the collector assembly  6 .  
         [0046]    The transfer assembly  8  includes a conduit  28 , which can comprise the same hydrophobic material as the second sponge  18 . The conduit  28  includes an inlet end  30  which is offset in order to overlie the second sponge drape opening  24  along the second sponge outer edge  26 . A conduit outlet end  32  mounts a buffer  34 , which also preferably comprises the hydrophobic foam and projects outwardly from the conduit  28  and receives a suction tube  36  which is also connected to the vacuum source (e.g., pump)  10 . A conduit drape  38  overlies the conduit  28  and includes an opening  40 , which receives the buffer  34 . A buffer drape  42  includes a first panel  42   a  and a second panel  42   b,  which are secured together over the buffer  34  and the suction tube  36  to enclose same. The buffer drape first and second panels  42   a,b  are mounted on the conduit drape  38  around the opening  40  therein.  
         [0047]    In operation, the hydrophilic first sponge  12  tends to collapse under negative pressure. Therefore, the size of the first sponge  12  is limited and it is preferably mounted in proximity to an edge  26  of the second sponge  18 . The second sponge  18  cooperates with the transfer assembly to distribute the negative pressure throughout the hydrophobic second sponge  18  and in turn throughout the first sponge  12 . The PVA material comprising the first sponge  12  permits it to compress under a negative pressure gradient. Moreover, because the fluid travel distance in the first sponge  12  tends to be relatively short due to its composition, the overlying second sponge  18  tends to distribute the negative pressure gradient relatively evenly across substantially the entire area of the first sponge  12 .  
         [0048]    The PUE composition of the second sponge  18  provides a reticulated latticework or weave which resists compression and includes relatively open passages to facilitate fluid flow. Although such open-lattice construction has operational advantages, the passages formed thereby in the second sponge  18  tend to receive “spicule” penetrations from the wound, which is undesirable in many applications. Therefore, the collector assembly  6  is constructed by first forming the first sponge  12  to generally conform to the wound  4 , whereafter the second sponge  18  is formed to provide the overhang  20 . The first sponge  12  is covered with the first sponge drape  14 , the opening  16  of which is normally sized smaller than the overall area of the first sponge  12 .  
         [0049]    The functional advantages of the collector assembly  6  construction include optimizing compression and fixation and edema control at the wound edge while maximizing the air-induced drying of the intact skin in the dry skin zone  17 . Moreover, collector assemblies and transfer assemblies can be mixed and configured in a wide variety of arrangements to accommodate various patient conditions. For example, multiple transfer assemblies  8  can be connected to a single collector assembly  6  and vice versa.  
         [0050]    III. First Modified Embodiment Fluid Differentiating Wound Dressing  53   
         [0051]    A wound dressing  53  comprising a first modified embodiment of the present invention is shown in FIG. 4 and includes a liner  54  between the wound  4  and a first sponge  56 , which can comprise a hydrophilic or hydrophobic material. The liner  54  passes fluid, but partially isolates and shields the wound tissue from the first sponge  56  to prevent the formation of spicules penetrating the open-passage first sponge  56 . The liner  54  thus permits the first sponge  56  to comprise hydrophobic (e.g., PUE) material, even when spicule penetration is not desired.  
         [0052]    IV. Second Modified Embodiment Fluid Differentiating Wound Dressing  102   
         [0053]    A wound dressing comprising a second modified embodiment of the present invention is shown in FIG. 5 and generally comprises a collector assembly  106  and a transfer assembly  108 . The collector assembly  106  can be similar to the collector assembly  6  with a suitable composite construction. The transfer assembly  108  comprises an elbow connector  110  placed on top of a second sponge drape  112  covering the second sponge  114 . The elbow connector  110  mounts the distal end  116  of a suction tube  118 , which is also connected to a vacuum source  10 . A first sponge drape  120  is placed over a first, hydrophilic sponge  122  and includes a central opening  123  communicating with the second sponge  114 .  
         [0054]    [0054]FIG. 5 a  shows an interface device  102   a  comprising a variation of the construction of the wound dressing  102 . The device  102   a  utilizes a flexible, bellows-type tubing section  110   a  in place of the elbow connector  110  described above. A needle-free, leur lock hub  124   a  is mounted on the end of the tubing section  110   a  and functions as an injection port. It will be appreciated that the sponge  122  can be omitted from the dressing  102   a  whereby same can be used as a fluid inlet or outlet in various applications and on many different configurations of dressings.  
         [0055]    V. Third Modified Embodiment Fluid Differentiating Wound Dressing  202   
         [0056]    A fluid differentiating wound dressing  202  comprising a third modified embodiment of the present invention is shown in FIGS.  6 - 8  and generally comprises a transfer assembly  204  (FIG. 6) adapted for mounting on a collector assembly  206  as shown in FIG. 7.  
         [0057]    The transfer assembly  204  comprises a sponge material buffer  208  which can comprise, for example, polyurethane ether (PUE). The buffer  208  is encased in first and second drape panels  210 ,  212  with wings  210   a,    212   a  respectively extending in opposite directions from the buffer  208 . The wings  210   a,    212   a  have an adhesive layer  214 , which is covered by a removable backing sheet  216  prior to installation. Tab strips  218  are provided at the ends of the drape wings  210   a,    212   a.  The tab strips  218  are attached by perforated lines  220  for easy removal upon installation. The suction tube  36  is embedded in the buffer  208  and extends outwardly from the transfer assembly  204  from between the first and second drape panels  210 ,  212 . An optional leur-lock hub  213  is mounted on the end of the tube  36  for injection port applications.  
         [0058]    The transfer assembly  204  is adapted for mounting on a collector assembly  206  (FIG. 7), which is similar to the collector assembly  6  described above. An opening  224  is formed in a second drape  222  which overlies a second sponge  218 . With the backing sheet  216  peeled away, the adhesive layer  214  on the drape panel wings  210   a,    212   a  secures the transfer assembly  204  in place whereby the buffer  208  is in communication with the second sponge  218  through the opening  224 . An optional first sponge  212  can be placed on the wound  4  and covered with drape  214  with an opening  216  formed therein. The dressing  202  can also be utilized with a single sponge for the collector assembly  206 .  
         [0059]    [0059]FIG. 8 shows an application of the dressing  202  wherein the transfer assembly  204  is mounted over a medial or interior portion  218   a  of the second sponge  218 . A first end  208   a  of the buffer  208  can be folded substantially flat on top of the second drape which overlies the second sponge  18 . A second end  208   b  of the buffer  208  extends outwardly from the collector assembly  206 . The buffer  208  can flex in response to pulling forces tugging on the suction tube  236 . The dressing  202  as shown in FIG. 8 is wrapped with drape strips  222 , which are adapted for encircling an extremity of a patient. Thus, the buffer first end  208   a  is secured by a drape strip  222  as shown. The drape strips  222  can be utilized for applying a compressive force to the dressing  202 . In operation, evacuating the dressing  202  causes portions of it to shrink, compress and collapse under the pressure gradient, thus providing a visual indication of its performance.  
         [0060]    VI. Fourth Modified Embodiment Fluid Differentiating Wound Dressing  302   
         [0061]    [0061]FIG. 9 shows a fluid differentiating wound dressing  302  comprising a fourth modified embodiment of the present invention. The dressing  302  includes a collector assembly  304  and a transfer assembly  306 . The collector assembly  304  includes first and second sponges  308 ,  310 . The first sponge  308  is mounted on the wound and can comprise, for example, a hydrophilic foam material as described above. The second sponge  310  can be mounted directly on the first sponge  308  (optionally separated by a drape) and can receive a tube  312  connected to a vacuum source. The second sponge  310  can include an overhang  313  extending beyond the first sponge  308  for providing a compression chamber  315  as described above. A drape  314  is placed over the collector assembly  304  and the tube  312 . The drape  314  is folded over the tube  312  whereby same is spaced outwardly from the skin, thus providing an effective, fluid-tight seal around the tube  312 .  
         [0062]    VII. Vacuum-Fixed Wound Therapy Method  
         [0063]    [0063]FIG. 10 shows a wound therapy method embodying the present invention. The method can be performed with one or more of the systems discussed above, including the vacuum-fixed dressings  3 ,  53 ,  102 ,  202  and  302 . The method can also be performed with a wide variety of variations on the systems and dressings disclosed above.  
         [0064]    VII. Fifth Modified Embodiment Wound Therapy and Tissue Management System  402   
         [0065]    [0065]FIG. 11 shows a wound therapy and tissue management system  402  comprising a fifth modified embodiment of the present invention. The system  402  includes a dressing  404  placed on a wound  406 . Any of the dressing systems discussed above can be utilized. The enclosure  414  is placed over the wound site  406  and includes an opening  416  extending therethrough and adapted for receiving a warming card  418  in covering relation thereover. The warming card  418  is operationally connected to a temperature control unit  420 . A vacuum assisted closure unit  408  is fluidically connected to the enclosure  414  by a suitable suction tube and in turn is connected to a power source  410 .  
         [0066]    In operation, the warming card  418  is heated and raises the temperature within the enclosure  414  to promote healing. The vacuum assisted closure  408  functions as described above to remove effluent and to promote healing in cooperation with the warming card  418 . Warming cards and other components for use in connection with this embodiment of the invention are available from Augustine Medical Products, Inc.  
         [0067]    IX. Sixth Modified Embodiment Wound Therapy and Tissue Management System  502   
         [0068]    [0068]FIG. 12 shows a wound therapy and tissue management system  502  comprising a sixth modified embodiment of the present invention. The system  502  is similar to the system  402  described above. A composite dressing  504  is comprised of first and second layers  506 ,  508 . A fluid source  518  communicates with a temperature control and pump unit  514  and provides influx to the system  502 .  
         [0069]    X. Seventh Modified Embodiment Wound Can&#39;t Therapy and Tissue Management System  602   
         [0070]    [0070]FIG. 13 shows a wound therapy and tissue management system  602  comprising a seventh modified embodiment of the present invention. The system  602  is similar to the systems  402  and  502  described above. A transfer element  604  is covered by a drape  620 , which mounts a film  616  adapted for receiving a warming card  618 .  
         [0071]    XI. Test Data  
         [0072]    [0072]FIGS. 14 a - 14   d  shows the results of tests performed with the dressing systems and methodologies discussed above and variations thereon. FIG. 14 a  shows system performance (time and temperature) with a dry PUE hydrophobic sponge material. FIG. 14 b  shows system performance with a wet PVA hydrophilic sponge material. FIG. 14 c  shows performance with an irrigated PUE hydrophobic sponge material with a warm-up plate (heating card) and a cover. FIG. 14 d  shows system performance with both PUE hydrophobic sponge material and PVA hydrophilic sponge material.  
         [0073]    XII. Wound Therapy and Tissue Management System  702   
         [0074]    [0074]FIGS. 15 and 16 show a wound therapy and tissue management system  702  comprising an eighth modified embodiment of the present invention. The system  702  is shown schematically in FIG. 15 and consists of inputs  704 , the patient  706 , outputs  708  and a feedback loop  710 . The inputs  704  can comprise virtually any matter or energy deemed appropriate for the treatment protocol by the health-care practitioner. For example, various irrigation fluids, growth factors, antibiotics, anesthetics, etc. can be input to the patient  706 . Still further, the inputs can comprise various forces and energy forms whereby a matter/energy gradient is established with respect to the patient  706 .  
         [0075]    For example, negative pressure from a suitable vacuum source (such as a VAC unit available from Kinetic Concepts, Inc. of San Antonio, Tex.) can be an input for creating a negative pressure gradient across the system. Likewise, positive pressure from a suitable fluid pump can be input to establish a positive pressure gradient across the system. Other forces can provide electromagnetic, electrical, mechanical and thermal gradients.  
         [0076]    The system  702  monitors performance of the patient  706  and controls the inputs  704  interactively in response thereto. Parameters which could be monitored for feedback purposes included moisture levels, temperature, bacteria levels, fluid pressure, etc. The presence or absence of particular elements and compounds can also be sensed, monitored and acted upon. For example, is widely known that oxygen is an important factor in wound healing. Studies have shown that reepithelialization and collagen production are best achieved by varying the oxygen supply. Thus, the oxygen level within the enclosed, wound site environment can be monitored and the oxygen levels therein either increased or decreased as necessary to promote healing. Other controllable parameters include the pH factor and the moisture concentration of the wound environment. Various suitable monitoring means can be employed, including electronic sensors, visual indicators, color-change substances, etc.  
         [0077]    The output from the patient can consist of fluid, such as effluent from the wound site, irrigation fluid removed in the process of flushing the wound site, and other matter and energy. An important function of the system is the removal of toxins and bacteria, which can be flushed from the wound site in a liquid or fluid solution.  
         [0078]    [0078]FIG. 16 is a block diagram of the system  702 , showing the components thereof in greater detail. A programmable controller  712  can be preprogrammed to operate the system according to predetermined protocols. The controller  712  is connected to and controls the operation of the input source  714  and the gradient source  716 . The input source  714  can comprise any suitable matter or energy for input to the system  702 , including various fluids, medications, thermal energy, mechanical forces, temperature, etc., as discussed above. The gradient source is likewise unlimited. For example, pressure gradients (both positive and negative) are particularly suitable for controlling the operation of the system  702  for draining wounds. Other types of gradients include temperature, osmotic, oncotic, pH, oxygen demand, bacteria concentrations, etc., as discussed above.  
         [0079]    A gradient source  716  can comprise any suitable device for establishing a gradient. For example, a vacuum source can be utilized for creating a negative pressure gradient. A pump can be utilized for creating a positive pressure gradient. A drape  718  is placed in covering relation over a transfer element  720 . The drape  718  can comprise any of the film materials discussed above and can be permeable, semi-permeable or impervious.  
         [0080]    The transfer element  720  includes a first zone  720   a  with a first set of fluid flow characteristics and a second zone  720   b  with a second set of fluid flow characteristics. Such fluid flow characteristics can be a function of material, thickness, porosity, permeability, and sponge material attraction to proteins, fat cells and other substances. The zones  720   a,b  can be formed by providing layers of the material, by providing varying thicknesses, by interspersing a first material within a second material in predetermined configurations, etc. Still further, the first and second zones can be formed by subjecting the transfer element  720  to an electromagnetic field.  
         [0081]    The first and second zones  720   a,b  can also be formed by varying the density of the transfer element  720 , as indicated by the dashed line  732  (FIG. 16). Line  732  represents compressed material (e.g., foam) along one edge and expanded material in the second zone  720   b.  Such density gradients can be achieved by compressing the material or by heat-setting same in a manufacturing process. Transfer element  720  edges can also be compressed when the dressing is applied to achieve a desired density gradient. Material thickness can also be utilized to provide a flow coefficient gradient. In this case line  732  could represent a tapering of the transfer element  720  across the first and second zones  720   a,    720   b.  A marbling effect with a material concentration gradient is shown at  733 , with greater concentration along an edge and decreasing concentration towards interior portions of the transfer element  720 , or vice-versa. Constructing the first and second zones  720   a,    720   b  of different materials with different respective flow coefficients could also achieve a desired flow gradient.  
         [0082]    Medications and other substances can be applied to the transfer element materials to alter the flow characteristics thereof. Systemic agents  731  can be administered to the patient  726 .  
         [0083]    Fluid  722  can be introduced into the wound site  724  from the inputs  714  and its flow pathways can be controlled by the gradient source  716 . For example, sponge materials with different flow characteristics can be configured to direct fluid (either gas or liquid) in predetermined flow patterns through the transfer element  720 . Effluent  728  from the patient  726  is withdrawn from the wound site  724  and evacuated to a collection receptacle  730 .  
         [0084]    XII. Wound Therapy and Tissue Management Methodology  
         [0085]    [0085]FIG. 17 shows a flowchart for a wound therapy and tissue management methodology embodying the president mentioned. From Start  804 , the method proceeds to Diagnose Patient Condition  806 . Based on the diagnosis, a treatment protocols selected. The protocol includes an identification of gradients to be controlled by the methodology. For example, protocols involving vacuum-assisted wound drainage will generally include a negative pressure gradient. Additional possible gradients are discussed above. It will be appreciated that virtually unlimited combinations of gradients can be formed in the system  702 . Moreover, the timing of the gradient control can be varied as needed to achieve desired treatment results. For example, collagen production and reepithelialization can be promoted by hyperbaric oxygen treatment procedures, such as alternating elevated and reduced oxygen concentrations. Suction/compressive pressures can also be alternated to stimulate tissue growth.  
         [0086]    Gradient sources are provided at  810  and can comprise vacuum/suction, fluids, medications, oxygen and various other matter and energy. Gradients can also be formed utilizing energy sources, such as thermal, mechanical force, etc. First and second transfer characteristics are selected at  812 ,  814  respectively. A transfer element(s) is provided at  816  and includes the transfer characteristics selected at  812 ,  814 . The patient is prepared at  818 . Patient preparations can include any suitable medical procedures, such as debriding the wound, etc.  
         [0087]    The transfer element is applied at  820  and draped at  822 . The transfer element is connected to a gradient source at  824  and the gradient is applied at  826 . Fluid is transferred through the first transfer element zone at  828  and through the second transfer element zone at  830 . It will be appreciated that such transfer zones can be adapted for directing the fluid along certain pathways to achieve desired results, such as evacuation of exudates. The fluid is differentiated (e.g., liquids, gases or liquids and gases are separated) at  832 .  
         [0088]    The operating parameters are monitored at  834  and the gradient source(s) are adjusted accordingly add  836 . Thereafter a “Continue?” decision box  838  is reached. If affirmative, the method returns to Apply Gradient  826  and operation continues with the adjusted gradient parameters. A negative decision at  838  leads to a termination of the procedure (i.e., “End”) at  840 .  
         [0089]    XIV. Osmolar Gradient Wound Therapy and Tissue Management System  902  and Methodology  
         [0090]    FIGS.  18 - 21  show a wound therapy and tissue management system  902  and methodology utilizing a controlled osmolar gradient. A patient  904  includes capillaries  906  which provide fluid, such as serum and blood, to a wound  908 . Such fluid passes to the transfer element  910 . An air sump control  914  communicates with the transfer element  910  through an air sump conduit  912 . A discharge control  918  communicates with the transfer element  910  through a discharge conduit  916 . The controls  914 ,  918  are interactively controlled by a controller  922 , which is adapted to receive control input signals. Such input signals can comprise, for example, preprogrammed inputs, feedback signals (FIG. 15), etc. The input signals can originate at sensors associated with the system  902  and with the patient  904 . Such inputs can effectively control the osmotic gradient to achieve desired fluid, solvent and solute (e.g., toxin) transfers. For example, the primary external substance input can comprise relatively dry ambient air. Air movement through the system  902  tends to collect moisture for discharge as water vapor.  
         [0091]    The system  902  is covered by a drape  920 , which can comprise various semi-permeable and impervious materials as required by fluid flow considerations and various applications. For example, an impervious drape  920  tends to block air from the system  902  and permit entry of same only through the air sump control  914 .  
         [0092]    [0092]FIG. 19 shows a hyperosmolar or air-sump system. Phase 1 represents a steady-state or increasing-toxin A condition and a concomitant increasing movement of toxin A back into the patient. In phase 2 a hyperosmolar solution or air sump is introduced. This gradient draws fluid from the capillaries to replace the fluid moved out of the wound into the transfer element carrying toxin A with it and decreasing movement of toxin A into the patient. Alternatively or in addition, warmed irrigating fluid can be introduced into the transfer element in phase 2. The advantages of warming the transfer element and wound site in this manner include vasodilation, increase in cell motility and an increase in phagocytosis. For example, irrigating fluid warmed to approximately 40 degrees centigrade has been shown to remove the inhibitory effect of chronic wound fluid on cell culture motility and proliferation.  
         [0093]    In phase 3, ongoing administration of this gradient continues these fluxes as water vapor is removed and dry air is sumped. Phase 4 results in a new steady-state condition with lower levels of toxin A in the wound (and the patient) and increased fluid and toxin A in the transfer element that is continuously evacuated.  
         [0094]    [0094]FIG. 20 shows an iso-osmolar or isotonic flush or rinse methodology. In phase 1 there is a steady-state (or increasing toxin A level) condition with fluid (liquids) moving out from the wound to the transfer element being replaced by serum exudate from the capillary. Evaporative loss from the transfer element is kept to a minimum by application of a drape material.  
         [0095]    In phase 2, an iso-osmolar rinse is introduced increasing the fluid content of the transfer element and decreasing the concentration of toxin A enabling a diffusion of toxin A from the wound into the transfer element. In phase 3, as this fluid is withdrawn, it also removes toxin A, enabling a continued diffusion of toxin A out of the wound. In phase 4, the resulting condition is fluid equilibrium and decreased concentration of toxin A in the wound. As this situation reverts to phase 1, the flush or rinse is repeated at intervals.  
         [0096]    [0096]FIG. 21 shows a hypo-osmolar or heavy drape system. In phase 1 steady-state conditions generally exist with some evaporative loss of fluid (water vapor). In phase 2, small amounts of hypo-osmolar fluid are introduced, or a cover/drape is placed over the transfer element with a heavy drape completely blocking evaporative loss, thus adding “free water” to the system. This reverses the outward flow of fluid from the wound.  
         [0097]    In phase 3 this increased fluid in the wound allows the total amount of toxin A to also accumulate in the wound. In phase 4 this increase of fluid and toxin A in the wound without any egress produces movement of fluid (edema) and toxins (cellulitis) back into the patient and into the lymphatics.  
         [0098]    Conclusion  
         [0099]    It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.  
         [0100]    Furthermore, it should be appreciated that continuations, divisionals, and continuations-in-part applications depending from this specification may be pending at the time this patent issues, the claims of which may encompass embodiments and applications that are broader than the claims appended herein. Accordingly, embodiments or elements disclosed in the specification but not literally claimed in the appended claims, if any, should not be presumed to be dedicated to the public.