Patent Document

BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The invention is generally directed to a therapeutic device and method for the promotion of wound healing. More particularly, the present invention relates to a method and device for providing intermittent negative pressure wound healing. 
         [0003]    2. Related Art 
         [0004]    Negative pressure wound therapy (NPWT), also known as vacuum drainage or closed-suction drainage, is known. A vacuum source is connected to a semi-occluded or occluded therapeutic member, such as a compressible wound dressing. Various porous dressings comprising gauze, felts, foams, beads and/or fibers can be used in conjunction with an occlusive semi-permeable cover and a controlled vacuum source. In addition to negative pressure, there exist pump devices configured to supply positive pressure to another therapeutic member, such as an inflatable cuff for various medical therapies. 
         [0005]    In addition to using negative pressure wound therapy, many devices employ concomitant wound irrigation. For example, a known wound healing apparatus includes a porous dressing made of polyurethane foam placed adjacent a wound and covered by a semi-permeable and flexible plastic sheet. The dressing further includes fluid supply and fluid drainage connections in communication with the cavity formed by the cover, foam and skin. The fluid supply is connected to a fluid source that can include an aqueous topical anesthetic or antibiotic solution, isotonic saline, or other medicaments for use in providing therapy to the wound. The fluid drainage can be connected to a vacuum source where fluid can be removed from the cavity and subatmospheric pressures can be maintained inside the cavity. The wound irrigation apparatus, although able to provide efficacious therapy, is somewhat cumbersome, difficult to use without trained professional medical personnel, and generally impractical outside the clinical setting. Such a device does not address various factors concerning patients outside clinical settings. 
         [0006]    Some devices use vacuum sealing of wound dressings consisting of polyvinyl alcohol foam cut to size and stapled to the margins of the wound. Such dressings are covered by a semi-permeable membrane while suction and fluid connections are provided by small plastic tubes which are introduced into the foam generally through the patient&#39;s skin. Currently, such devices alternate in time between vacuum drainage and the introduction of aqueous medicaments to the wound site, but do not do both simultaneously. Also, current devices in the market place provide therapy using vacuum to apply negative pressure for a period of time (a “pressure application” mode) and then release vacuum and negative pressure (a so-called “relaxation” mode). While the prior devices have proven to be useful therapy, there remains a need to improve on the devices and methods of applying negative pressure wound therapy. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object to improve wound healing. 
         [0008]    It is another object to improve devices for use in treating wounds. 
         [0009]    It is an object to improve methods for treating wounds. 
         [0010]    It is yet another object to improve wound therapy by treating with novel intermittent negative pressure routines. 
         [0011]    It is yet another object to provide a therapeutic device for treating wounds which is equipped for predetermined therapy parameters of time and pressure. 
         [0012]    One embodiment of the invention is directed to a method for providing intermittent negative pressure wound healing which includes the steps of (a) applying a negative pressure compressible therapeutic dressing about a wound (b) compressing the therapeutic dressing using negative pressure to subject the wound and the therapeutic dressing to a first predetermined pressure which is low enough to provide therapy to the wound and high enough to maintain a seal between the dressing and the wound; and (c) decompressing the therapeutic dressing to a second sub-atmospheric pressure above the first predetermined pressure sufficient to maintain the dressing in a generally sealed contact with the wound while relaxing compression about the wound. The step (b) can be further characterized to be compressing to a sub-atmospheric pressure between about a range of −50 mmHg to −500 mmHg. The step (c) can be further characterized to be decompressing to about a range of −10 mmHg and −40 mmHg. The method can include the step (d) of repeating steps (b) and (c) for a predetermined period. Step (b) can be performed for a first predetermined time and step (c) can be performed for a second predetermined time wherein the first predetermined time and the second predetermined time may or may not be the same. Another variation is in the step (d) of repeating step (b) and decompressing the therapeutic dressing to a third sub-atmospheric pressure above the first predetermined pressure sufficient to maintain the dressing in a generally sealed contact with the wound wherein the third sub-atmospheric pressure is not equal to the second sub-atmospheric pressure. 
         [0013]    A therapeutic device for providing intermittent negative pressure wound healing includes fluid moving means for one of raising, compressing, or transferring fluid, a compressible therapeutic member operably connected to the fluid moving means and actuated thereby, the compressible therapeutic member operably disposably used on a patient in a manner to deliver therapy to the patient as a function of actuation of the fluid moving means; and control means operably associated with the fluid moving means for controlling application of a negative pressure to the compressible therapeutic member about a wound in a manner to compress the compressible therapeutic member using negative pressure to subject the wound and the compressible therapeutic member to a first predetermined pressure which is low enough to provide therapy to the wound and high enough to maintain a seal between the compressible therapeutic member and the wound and decompressing the compressible therapeutic member to a second sub-atmospheric pressure above the first predetermined pressure sufficient to maintain the compressible therapeutic member in generally sealed contact with the wound while relaxing compression about the wound, and a power source to supply power to the fluid moving means and control means. 
         [0014]    Control means can also preferably control operation of the device in a manner to restrict use of the fluid moving means by the patient in accordance with a predetermined treatment plan or duration and render the pump inoperable thereafter. The power source can be a chargeable power source. 
         [0015]    More particularly, a wound irrigation system can use a fluid moving means, such as a diaphragm or piston-type pump, to raise, compress and transfer fluid in an electromechanical vacuum apparatus that includes a control means, such as a microprocessor-based device, having stored thereon software configured to control the electromechanical vacuum apparatus, and including one of a timer, means for remote control of the system, and means to restrict the operation of the apparatus to a predetermined treatment plan or duration. 
         [0016]    A first vacuum pump can be electrically associated with the microcontroller and capable of generating a vacuum. An optional second vacuum pump is electrically associated with the microcontroller and is capable of maintaining a predetermined vacuum level. A first electronic vacuum-pressure sensor can be operably associated with the vacuum pump(s) and the microcontroller for monitoring vacuum level. 
         [0017]    A fluid-tight wound exudate collection canister can be provided and can include an integrated barrier, such as a float valve, porous polymer filter or hydrophobic filter, to prevent contents from escaping the canister. Single-lumen tubing can be associated with the canister and vacuum pump(s) for communicating vacuum pressure therefrom. A second electronic vacuum-pressure sensor can be operably associated with the canister and the microcontroller for monitoring canister vacuum. 
         [0018]    A dressing includes a porous material and semi-permeable flexible cover. Single-lumen tubing is associated with the dressing and the canister to communicate vacuum pressure therefrom. An irrigation vessel can be provided to contain a fluid to be used in irrigating the wound. Single-lumen tubing is associated with the irrigation vessel and the dressing to communicate fluid thereto. 
         [0019]    The electromechanical vacuum apparatus housing may incorporate a compartment that can hold the irrigation vessel. The electromechanical vacuum apparatus can preferably include a device for regulating the quantity of fluid flowing from said irrigation vessel to said dressing. This device can comprise a mechanical, electrical or pneumatically actuated valve or clamp. 
         [0020]    The electromechanical vacuum apparatus may include commercially available storage batteries enabling portable operation thereof. Alternative power sources include rechargeable or reprocessable batteries which are removably connected to a housing, which contains the fluid moving means and control means, both of which require power in a waterproof environment. Other alternative power sources are solar energy, a manually operated generator in combination with a storage device such as a supercapacitor, a pneumatic accumulator or an ac power source. 
         [0021]    An embodiment of the invention includes a method for improving the generation and control of a therapeutic vacuum. In this embodiment, a multi-modal algorithm monitors pressure signals from a first electronic vacuum-pressure sensor associated with a vacuum pump and capable of measuring the output pressure from the pump. The algorithm further monitors pressure signals from a second electronic vacuum-pressure sensor associated with a collection canister and capable of measuring the subatmospheric pressure inside the canister. The second electronic vacuum-pressure sensor may also be associated with the wound dressing and capable of measuring the subatmospheric pressure inside the dressing. The canister is connected to the vacuum pump by a single-lumen tube that communicates subatmospheric pressure therefrom. The canister is connected to a suitable dressing by a single-lumen tube that communicates subatmospheric pressure thereto. 
         [0022]    At the start of therapy, both the first and second electronic vacuum-pressure sensors indicate the system is equilibrated at atmospheric pressure. A first-mode control algorithm is employed to rapidly remove the air in the canister and dressing, and thus create a vacuum. The first-mode implemented by the control algorithm is subsequently referred to herein as the “draw down” mode. Once the subatmospheric pressure in the canister and dressing have reached a preset threshold as indicated by the first and second electronic vacuum-pressure sensors respectively, the algorithm employs a second-mode that maintains the desired level of subatmospheric pressure in both the canister and the dressing for the duration of the therapy. The second-mode implemented by the control algorithm is subsequently referred to herein as the “maintenance” mode. A third-mode control algorithm can preferably be employed to release vacuum rapidly in the canister and dressing to a predetermined sub-atmospheric pressure which is sufficient to maintain a seal between the therapeutic dressing and the wound which is subsequently referred to herein as the “seal down-without compression” mode. Once seal down-without compression mode is held for a predetermined time, the algorithm can employ the second-mode that maintains the desired level of subatmospheric pressure in both the canister and the dressing for the duration of the therapy. The algorithm can vary the time and pressure for each mode as a function of patient condition and sensed conditions. 
         [0023]    The second-mode control algorithm can also be configured to operate the vacuum pump at a reduced speed thus minimizing unwanted mechanical noise. In an alternative embodiment, a second vacuum pump can be used for the maintenance mode, which has a reduced capacity, is smaller, and produces significantly lower levels of unwanted mechanical noise. The second-mode control algorithm is configured to permit the maintenance of vacuum in the presence of small leaks, which invariably occur at the various system interfaces and connection points. The method can be performed by, for example, a microprocessor-based device. 
         [0024]    The control means (microcontroller or microprocessor) can be provided with a timer for restricting the use as a function of a predetermined time. Alternatively, an identification member can be provided with the device such that the control means restricts use as a function of the identification member. The control means may include a Radio Frequency Identification Chip (RFID) chip available under the trademark Omni-ID™ The control means can further be operably associated with a remote control for restricting the use of the device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a schematic illustrating the device of the invention. 
           [0026]      FIG. 1A  depicts part of the invention on a wound. 
           [0027]      FIG. 2  illustrates a graph showing a prior art negative pressure therapy application. 
           [0028]      FIG. 3  illustrates a graph showing negative pressure therapy application according to one embodiment of the invention. 
           [0029]      FIG. 4  illustrates a graph showing negative pressure therapy application according to another embodiment of the invention. 
           [0030]      FIG. 5  illustrates a graph showing negative pressure therapy application according to yet another embodiment of the invention. 
           [0031]      FIG. 6  illustrates a graph showing negative pressure therapy application according to yet another embodiment of the invention. 
           [0032]      FIG. 7  illustrates a graph showing negative pressure therapy application according to yet another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    As illustrated in  FIG. 1 , a therapeutic device of the instant invention is generally designated by the numeral  10 . The therapeutic device  10  can preferably include a housing  12  which provides an improved therapeutic device with multiple uses and portability. The housing  12  can preferably be formed in a waterproof manner to protect components therein. In this regard, housing  12  can have a watertight sealed access panel  13  through which components can be accessed. 
         [0034]    The device  10  can include a processor  14 , which can be a microcontroller having an embedded microprocessor, Random Access Memory (RAM) and Flash Memory (FM). FM can preferably contain the programming instructions for a control algorithm. FM can preferably be non-volatile and retains its programming when the power is terminated. RAM can be utilized by the control algorithm for storing variables such as pressure measurements, alarm counts and the like, which the control algorithm uses while generating and maintaining the vacuum. 
         [0035]    The embodiments illustrated in  FIGS. 3-7  show various therapeutic regimens of the instant invention. An embodiment of the invention includes a method for improving the generation and control of a therapeutic vacuum. In this embodiment, a multi-modal algorithm monitors pressure signals from a first electronic vacuum-pressure sensor associated with vacuum pumps  18 / 20  and is capable of measuring the output pressure from the pump  18 / 20 . The algorithm further monitors pressure signals from a second electronic vacuum-pressure sensor  42  associated with a collection canister  22  and capable of measuring the subatmospheric pressure inside the canister  22 . The canister  22  is connected to the vacuum pump  18 / 20  by single-lumen tube  24  that communicates subatmospheric pressure therefrom. The canister  22  is connected to dressing  11  by single-lumen tube  44  that communicates subatmospheric pressure thereto. 
         [0036]    At the start of therapy, both the first and second electronic vacuum-pressure sensors  34 ,  42  indicate the device  10  is equilibrated at atmospheric pressure. A first-mode control algorithm is employed to rapidly remove the air in the canister  22  and dressing  11 , and thus create a vacuum. The first-mode implemented by the control algorithm is subsequently referred to herein as the “draw down” mode from 0 mm Hg at t 1 . Once the subatmospheric pressure in the canister  22  and dressing  11  have reached a preset threshold as indicated by the first and second electronic vacuum-pressure sensors  34 ,  42  respectively, the algorithm employs a second-mode that maintains the desired level of subatmospheric pressure in both the canister  22  and the dressing  11  for the duration of the therapy. The second-mode implemented by the control algorithm is subsequently referred to herein as the “maintenance” mode t 2 . A third-mode control algorithm can preferably be employed to release vacuum rapidly in the canister  22  and dressing  11  to a predetermined sub-atmospheric pressure which is sufficient to maintain a seal between the therapeutic dressing  11  and the wound W which is subsequently referred to herein as the “seal down-without compression” mode t 3 . Once seal down-without compression mode is held for a predetermined time, the algorithm can optionally employ the second-mode that maintains the desired level of subatmospheric pressure in both the canister  22  and the dressing  11  for the duration of the therapy. The algorithm can vary the time and pressure for each mode as a function of patient condition and sensed conditions. 
         [0037]    The second-mode control algorithm can also be configured to operate the vacuum pump  18  at a reduced speed thus minimizing unwanted mechanical noise. In an alternative embodiment, second vacuum pump  20  can be used for the maintenance mode, which has a reduced capacity, is smaller, and produces significantly lower levels of unwanted mechanical noise. The second-mode control algorithm is configured to permit the maintenance of vacuum in the presence of small leaks, which invariably occur at the various system interfaces and connection points. The method can be performed by, for example, microcontroller  14 . 
         [0038]      FIG. 3  depicts the method of operation wherein the time periods for maintenance mode and seal down without compression are generally the same and pressures for each subsequent maintenance mode remain the same and pressures for each subsequent seal down without compression mode remain the same.  FIG. 4  depicts the method of operation wherein the time periods for maintenance mode and seal down without compression vary and pressures for each subsequent maintenance mode remain generally the same and pressures for each subsequent seal down without compression mode remain generally the same.  FIG. 5  depicts the method of operation wherein the time periods for maintenance mode and seal down without compression remain generally the same and pressures for each subsequent maintenance mode remain generally the same and pressures for each subsequent seal down without compression mode remain vary.  FIG. 6  depicts the method of operation wherein the time periods for maintenance mode and seal down without compression remain generally the same and pressures for each subsequent maintenance mode vary and pressures for each subsequent seal down without compression mode remain generally the same.  FIG. 7  depicts the method of operation wherein the time periods for maintenance mode and seal down without compression vary and pressures for each subsequent maintenance mode vary and pressures for each subsequent seal down without compression mode vary. Other permutations may be employed with and controlled by the microcontroller  14  as a function of one or more sensed conditions in the dressing  11 , canister  22  or patient. A membrane keypad and a light emitting diode LED or liquid crystal display (LCD)  16  can be electrically associated with processor  14  through communication link, such as a cable. Keypad switches provide power control and are used to preset the desired pressure/vacuum levels. Light emitting diodes  17 ,  19  can be provided to indicate alarm conditions associated with canister fluid level, leaks of pressure in the dressing and canister, and power remaining in the power source. 
         [0039]    Microcontroller  14  is electrically associated with, and controls the operation of, a first vacuum pump  18  and an optional second vacuum pump  20  through electrical connections. First vacuum pump  18  and optional second vacuum pump  20  can be one of many types including, for example, the pumps sold under the trademarks Hargraves® and Thomas®. Vacuum pumps  18  and  20  can use, for example, a reciprocating diaphragm or piston to create vacuum and can be typically powered by a direct current (DC) motor that can also optionally use a brushless commutator for increased reliability and longevity. Vacuum pumps  18  and  20  can be pneumatically associated with an exudate collection canister  22  through a single-lumen tube  24 . 
         [0040]    In one embodiment, canister  22  has a volume which does not exceed 1000 ml. This can prevent accidental exsanguination of a patient in the event hemostasis has not yet been achieved at the wound site. Canister  22  can be of a custom design or one available off-the-shelf and sold under the trademark DeRoyal®. 
         [0041]    In addition, a fluid barrier  26 , which can be a back flow valve or filter, is associated with canister  22  and is configured to prevent fluids collected in canister  22  from escaping into tubing  24  and fouling the vacuum return path. Barrier  26  can be of a mechanical float design or may have one or more membranes of hydrophobic material such as those available under the trademark GoreTex™. Barrier  26  can also be fabricated from a porous polymer such as that which is available under the trademark MicroPore™ A secondary barrier  28  using a hydrophobic membrane or valve is inserted in-line with pneumatic tubing  24  to prevent fluid ingress into the system in the event barrier  26  fails to operate as intended. Pneumatic tubing  24  can connect to first vacuum pump  18  and optional second vacuum pump  20  through “T” connectors. 
         [0042]    An identification member  30 , such as radio frequency identification (RFID) tag, can be physically associated with the canister  22  and an RFID sensor  32  operably associated with the microcontroller  14  such that the microcontroller  14  can restrict use of the device  10  to a predetermined canister  22 . Thus, if a canister  22  does not have a predetermined RFID chip, the device  10  will not operate. Another embodiment envisions software resident on microcontroller  14  which restricts the use of the device  10  to a predetermined time period such as 90 days for example. In this way, the patient using the device  10  may use the device  10  for a prescribed time period and then the device  10  automatically times out per a particular therapeutic plan for that patient. This also enables a reminder of the time and date for the next dressing change or physician appointment. It is also contemplated that the microcontroller  14  be operably provided with a remote control  15  and communication link, such as a transceiver, wherein the device  10  can be shut down remotely when a particular therapeutic plan for that patient has ended. Likewise, remote control  15  can be utilized to provide additional time after the therapeutic device times out. 
         [0043]    Vacuum-pressure sensor  34  is pneumatically associated with first vacuum pump  18  and optional vacuum pump  20  and electrically associated with microcontroller  14 . Pressure sensor  34  provides a vacuum-pressure signal to the microprocessor enabling a control algorithm to monitor vacuum pressure at the outlet of the vacuum pumps  18  and  20 . 
         [0044]    An acoustic muffler can be provided and pneumatically associated with the exhaust ports of vacuum pumps  18  and  20  and configured to reduce exhaust noise produced by the pumps during operation. In normal operation of device  10 , first vacuum pump  18  can be used to generate the initial or “draw-down” vacuum while optional second vacuum pump  20  can be used to maintain a desired vacuum within the system compensating for any leaks or pressure fluctuations. Vacuum pump  20  can be smaller and quieter than vacuum pump  18  providing a means to maintain desired pressure without disturbing the patient. It is contemplated by the instant invention that pumps  18  and  20  can also be employed to create a positive pressure for purposes of applying pressure to an inflatable member  35 , such as a cuff, through tubing  36 . A switch  37  can be operatively disposed on housing  12  in operable connection with microcontroller  14  to enable selection of positive and negative pressure from pumps  18 / 20 . 
         [0045]    One or more battery (ies)  38  can preferably be provided to permit portable operation of the device  10 . Battery  38  can be Lithium Ion (LiIon), Nickel-Metal-Hydride (NiMH), Nickel-Cadmium, (NiCd) or their equivalent, and can be electrically associated with microcontroller  14  through electrical connections. Battery  38  can be of a rechargeable type which is preferably removably disposed in connection with the housing  12  and can be replaced with a secondary battery  38  when needed. A recharger  40  is provided to keep one battery  38  charged at all times. Additionally, it is contemplated that the device  10  can be equipped to be powered or charged by recharger  40  or by circuits related with microcontroller  14  if such source of power is available. When an external source of power is not available and the device  10  is to operate in a portable mode, battery  38  supplies power to the device  10 . The battery  38  can be rechargeable or reprocessable and can preferably be removably stored in a waterproof manner within housing  12  which also likewise contains the pumps  18 ,  20  and microcontroller  14 . 
         [0046]    A second pressure sensor  42  is pneumatically associated with canister  22  through a sensor port  43 . Pressure sensor  42  can be electrically associated with microcontroller  14  and provides a vacuum-pressure signal to microprocessor enabling control algorithm to monitor vacuum pressure inside canister  22  and dressing  11 . A “T” connector can be connected to port  43 , to pressure sensor  42  and a vacuum-pressure relief solenoid  46  configured to relieve pressure in the canister  22  and dressing  11  in the event of an alarm condition, or if power is turned off. Solenoid  46 , can be, for example, one available under the trademark Parker Hannifin® or Pneutronics®; Solenoid  46  is electrically associated with, and controlled by, microprocessor of microcontroller  14 . Solenoid  46  can be configured to vent vacuum pressure to atmosphere when an electrical coil associated therewith is de-energized as would be the case if the power is turned off. An orifice restrictor  48  may optionally be provided in-line with solenoid  46  and pneumatic tube  44  to regulate the rate at which vacuum is relieved to atmospheric pressure when solenoid  46  is de-energized. Orifice restrictor  48  is, for example, available under the trademark AirLogic®. 
         [0047]    A wound dressing  11  can preferably include a sterile porous substrate  50 , which can be a polyurethane foam, polyvinyl alcohol foam, gauze, felt or other suitable material, a semi-permeable adhesive cover  52  such as that sold under the trademark DeRoyal® or Avery Denison®, an inlet port  56  and a suction port  54 . Substrate  50  is configured to distribute vacuum pressure evenly throughout the entire wound bed and has mechanical properties suitable for promoting the formation of granular tissue and approximating the wound margins. 
         [0048]    In addition, when vacuum is applied to dressing  11 , substrate  50  creates micro- and macro-strain at the cellular level of the wound stimulating the production of various growth factors and other cytokines, and promoting cell proliferation. Dressing  11  is fluidically associated with canister  22  through single-lumen tube  44 . The vacuum pressure in a cavity formed by substrate  50  of dressing  11  is largely the same as the vacuum pressure inside canister  22  minus the weight of any standing fluid inside tubing  44 . 
         [0049]    A fluid vessel  60 , which can be a standard TV bag, contains medicinal fluids such as aqueous topical antibiotics, analgesics, physiologic bleaches, or isotonic saline. Fluid vessel  60  is removably connected to dressing  11  though port  56  and single-lumen tube  62 . 
         [0050]    An optional flow control device  64  can be placed in-line with tubing  62  to permit accurate regulation of the fluid flow from vessel  60  to dressing  11 . In normal operation, continuous wound site irrigation is provided as treatment fluids move from vessel  60  through dressing  11  and into collection canister  22 . This continuous irrigation keeps the wound clean and helps to manage infection. In addition, effluent produced at the wound site and collected by substrate  50  will be removed to canister  22  when the system is under vacuum. 
         [0051]    The device  10  is particularly well suited for providing therapeutic wound irrigation and vacuum drainage and provides for a self-contained plastic housing configured to be worn around the waist or carried in a pouch over the shoulder for patients who are ambulatory, and hung from the footboard or headboard of a bed for patients who are non-ambulatory. Membrane keypad and display  16  is provided to enable the adjustment of therapeutic parameters and to turn the unit on and off. 
         [0052]    Depressing the power button on membrane switch  16  will turn the power to device  10  on/off. While it is contemplated that the membrane switch  16  be equipped with keys to adjust therapeutic pressure up and down, the microcontroller  14  can preferably be equipped to control the pressure in accordance with sensed pressure and condition to maintain pressure in an operable range between −70 mmHg and −150 mmHg with a working range of between 0 and −500 mmHg, for example. Although these pressure settings are provided by way of example, they are not intended to be limiting because other pressures can be utilized for wound-type specific applications. The membrane  16  can also be equipped with LED  17  to indicate a leak alarm and/or LED  19  indicates a full-canister alarm. When either alarm condition is detected, these LEDs will light in conjunction with an audible chime which is also included in the device  10 . 
         [0053]    Housing  12  can incorporate a compartment configured in such a way as to receive and store a standard IV bag  60  or can be externally coupled to thereto. IV bag  60  may contain an aqueous topical wound treatment fluid that is utilized by the device  60  to provide continuous irrigation. A belt clip can be provided for attaching to a patient&#39;s belt and an optional waist strap or shoulder strap is provided for patients who do not or cannot wear belts. 
         [0054]    Canister  22  is provided for exudate collection and can preferably be configured as currently known in the field with a vacuum-sealing means and associated fluid barrier  26 , vacuum sensor port  43  and associated protective hydrophobic filter, contact-clear translucent body, clear graduated measurement window, locking means and tubing connection means. Collection canister  22  typically has a volume less than 1000 ml to prevent accidental exsanguination of a patient if hemostasis is not achieved in the wound. Fluid barriers  26  can be, for example, those sold under the trademark MicroPore® or GoreTex® and ensure the contents of canister  22  do not inadvertently ingress into pumps  18 ,  20  of housing  12  and subsequently cause contamination thereof. 
         [0055]    Vacuum pressure sensor  42  enables microcontroller  14  to measure the pressure within the canister  22  as a proxy for the therapeutic vacuum pressure under the dressing  11 . Optionally, tubing  62  can be multilumen tubing providing one conduit for the irrigation fluid to travel to dressing  11  and another conduit for the vacuum drainage. Thus, IV bag  60 , tubing  62 , dressing  11  and canister  22  provide a closed fluid pathway. In this embodiment, canister  22  would be single-use disposable and may be filled with a solidifying agent  23  to enable the contents to solidify prior to disposal. Solidifying agents are available, for example, under the trademark DeRoyal® and Isolyzer®. The solidifying agents prevent fluid from sloshing around inside the canister particularly when the patent is mobile, such as would be the case if the patient were travelling in a motor vehicle. In addition, solidifying agents are available with antimicrobials that can destroy pathogens and help prevent aerosolization of bacteria. 
         [0056]    At the termination of optional multilumen tubing  62 , there can be provided a self-adhesive dressing connector  57  for attaching the tubing to drape  52  with substantially air-tight seal. Dressing connector  57  can have an annular pressure-sensitive adhesive ring with a release liner that is removed prior to application. Port  56  can be formed as a port cut in drape  52  and dressing connector  57  would be positioned in alignment with said port. This enables irrigation fluid to both enter and leave the dressing through a single port. In an alternative embodiment, tube  62  can bifurcate at the terminus and connect to two dressing connectors  57  which allow the irrigation port to be physically separated from the vacuum drainage port thus forcing irrigation fluid to flow though the entire length of the dressing if it is so desired. Similarly, port  54  and connector  55  can be provided to connect optional multilumen tubing  44  to dressing  11 . In this arrangement, the second lumen may be used to directly measure the pressure in dressing  11 . 
         [0057]    Fluid vessel  60  can be of the type which includes a self-sealing needle port situated on the superior aspect of the vessel  60  and a regulated drip port situated on the inferior aspect of the vessel. The needle port permits the introduction of a hypodermic needle for the administration of aqueous topical wound treatment fluids. These aqueous topical fluids can include a topical anesthetic such as Lidocaine, antibiotics such as Bacitracin or Sulfamide-Acetate; physiologic bleach such as Chlorpactin or Dakins solution; and antiseptics such as Lavasept or Octenisept. Regulated drip port permits fluid within vessel  60  to egress slowly and continuously into porous substrate  50  whereupon the therapeutic benefits can be imparted to the wound site. Single-lumen drainage tube  44  provides enough vacuum to keep the dressing  11  at sub-atmospheric pressure and to remove fluids, which include the irrigation fluid and wound exudate. With this modification, the need for an external fluid vessel and associated tubing and connectors can be eliminated making the dressing more user friendly for patient and clinician alike. 
         [0058]    In typical clinical use of this alternate embodiment, dressing  11  is applied to the wound site by first cutting porous substrate  50  to fit the margins of the wound. Next, semi-permeable drape  52  is attached and sealed over the dressing and periwound. A hole approximately ⅜″ diameter can be made in drape  52  central to porous substrate  50 . Fluid vessel  60  is attached by adhesive annular ring  57  with port  56  aligned with the hole previously cut in drape  52 . Once the fluid vessel  60  is hermitically sealed to the drape  52 , a properly prepared hypodermic needle is inserted in self-sealing needle port and fluid vessel  60  subsequently filled with the desired aqueous topical wound treatment solution. 
         [0059]    For the majority of applications, the technique for providing therapeutic wound irrigation and vacuum drainage is illustrated. The single lumen drainage tube  44  is provided for the application of vacuum and removal of fluids from the wound site. Fluid vessel  60  can be situated outside and superior to semi-permeable substrate  50 . An annular adhesive ring  57  is provided on port  56  for attachment of single-lumen irrigation tubing  62  to drape  52 . Similarly, a needle port permits the introduction of a hypodermic needle for the administration of aqueous topical wound treatment fluids as described above, for example, a caregiver may want to add a topical antibiotic to a bag of isotonic saline. Adjustable drip port  64  permits fluid within vessel  60  to egress slowly and continuously into porous substrate  50  through hole  56  in drape  52  whereupon the therapeutic benefits can be imparted to the wound site. Single-lumen drainage tube  44  provides enough vacuum to keep the dressing  11  at sub-atmospheric pressure and to remove fluids which include the irrigation fluid and wound exudate. 
         [0060]    Because of the potential chemical interactions between the various materials used in the construction of dressing  11 , attention must be paid to the types of aqueous topical wound fluids used to ensure compatibility. The above described embodiments are set forth by way of example and are not limiting. It will be readily apparent that obvious modifications, derivations and variations can be made to the embodiments. For example, the vacuum pumps described having either a diaphragm or piston-type could also be one of a syringe based system, bellows, or even an oscillating linear pump. Accordingly, the claims appended hereto should be read in their full scope including any such modifications, derivations and variations.

Technology Category: a