Patent Publication Number: US-2012035560-A1

Title: Wound treatment system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/936,048, which was the National Stage of International Application No. PCT/US2009/039156, filed on Apr. 1, 2009, which claims the benefit of U.S. Provisional Patent Application No. 61/041,301, filed on Apr. 1, 2008, the entire disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is generally directed to a system for treating wounds and, more specifically, to a system for treating wounds by applying a vacuum to the wound site. 
     Wound treatment systems that treat a wound using a vacuum or negative pressure are known. Examples of such systems are disclosed in U.S. Pat. Nos. 4,382,441, 4,392,858, 4,655,754, 4,826,494, 4,969,880, 5,100,396, 5,261,893, 5,527,293, 5,636,643, 5,645,081, 6,071,267, 6,117,111, 6,135,116, 6,142,982, 6,174,306, 6,345,623, 6,398,767, 6,520,982, 6,553,998, 6,814,079, 7,198,046, and 7,216,651. These systems utilize either a manual pump, or a portable vacuum pump to draw air and fluid from the wound site. Such portable pumps can be expensive and take up valuable space in the hospital recovery rooms. 
     A related commonly-assigned published U.S. Patent Application Publication No. US 2009/0043268 A1 discloses a wound treatment system that may use an existing vacuum system of a hospital or healthcare facility, either remote or central. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a system is provided for the treatment of wounds by applying a negative pressure to a wound site. The system comprises a suction regulator and a wound dressing. The suction regulator comprises a vacuum regulator for supplying a negative pressure to the wound site, and a control circuit coupled to the vacuum regulator for generating control signals for controlling the vacuum regulator to selectively supply the negative pressure to the wound site. The wound dressing is provided at the wound site and coupled to the vacuum regulator. The wound dressing comprises a wound dressing pad for placing over the wound, and a wound drape provided over the wound dressing pad and the wound site for securing the wound dressing pad and sealing the wound site for application of the negative pressure. The system further comprises a pressure verification mechanism in communication with the wound site for providing visual verification that the negative pressure applied to the wound site has reached a predetermined pressure level. 
     According to another aspect of the present invention, a system is provided for the treatment of wounds by applying a negative pressure to a wound site. The system comprises a wound dressing and a suction regulator. The suction regulator comprises a vacuum regulator for supplying a negative pressure to the wound site, and a control circuit coupled to the vacuum regulator for generating control signals for controlling the vacuum regulator to selectively supply the negative pressure to the wound site. The wound dressing is provided at the wound site and coupled to the vacuum regulator. The wound dressing comprises a wound dressing pad for placing over the wound, and a wound drape provided over the wound dressing pad and the wound site for securing the wound dressing pad and sealing the wound site for application of the negative pressure. The system further comprises a venting mechanism for allowing oxygen to vent to the wound site when the negative pressure is not supplied to the wound site. 
     According to another aspect of the present invention, a system is provided for the treatment of wounds by applying a negative pressure to a wound site. The system comprises a wound dressing and a suction regulator. The suction regulator comprises: a vacuum regulator for supplying a negative pressure to the wound site, a flow sensor for sensing a flow rate from the wound site, and a control circuit coupled to the flow sensor and to the vacuum regulator for generating control signals for controlling the vacuum regulator, the control circuit generating an alarm signal if the flow rate sensed by the flow sensor exceeds a threshold. The wound dressing is provided at the wound site and coupled to the vacuum regulator. The wound dressing comprises a wound dressing pad for placing over the wound, and a wound drape provided over the wound dressing pad and the wound site for securing the wound dressing pad and sealing the wound site for application of the negative pressure. 
     According to another aspect of the present invention, a system is provided for the treatment of wounds by applying a negative pressure to a wound site. The system comprises a wound dressing and a suction regulator. The suction regulator comprises a vacuum regulator for supplying a negative pressure to the wound site, and a control circuit coupled to the vacuum regulator for generating control signals for controlling the vacuum regulator to selectively supply the negative pressure to the wound site. The wound dressing provided at the wound site and coupled to the vacuum regulator. The wound dressing comprises a wound dressing pad for placing over the wound, and a wound drape provided over the wound dressing pad and the wound site for securing the wound dressing pad and sealing the wound site for application of the negative pressure. The wound dressing pad comprises a support material at least partially covered with silicone. 
     According to another aspect of the present invention, a wound dressing pad is provided for use in a system for the treatment of wounds by applying a negative pressure to a wound site. The wound dressing pad comprises a support material at least partially covered with silicone for application to a wound at the wound site. 
     These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1A  is a perspective view of a portion of a wound treatment system according to one embodiment of the present invention; 
         FIG. 1B  is a perspective view of a portion of a wound treatment system according to another embodiment of the present invention; 
         FIG. 2  is a fluid flow and electrical circuit diagram in block form of a wound treatment system according to the present invention; 
         FIG. 3  is an electrical circuit diagram in block form of a suction regulator according to the present invention; 
         FIG. 4  is a perspective view of a wound dressing portion that may be used in the inventive wound treatment system; 
         FIG. 5  is a cross-sectional view of the wound dressing portion shown in  FIG. 4  taken along line  2 - 2 ; 
         FIG. 6  is a top view of the wound dressing portion shown in  FIG. 4 ; 
         FIG. 7  is a cut-away perspective view of a portion of the bottom surface of a drape of the wound dressing portion shown in  FIGS. 4 and 6 ; 
         FIG. 8  is a plan view of the bottom surface of an attachment pad that may be used in the inventive wound treatment system; 
         FIG. 9  is a side view of the attachment pad shown in  FIG. 8 ; 
         FIG. 10  is a side view of the attachment pad shown in  FIG. 8  shown when in use in the inventive wound treatment system; 
         FIG. 11  is a perspective view of a wound dressing portion configured for attachment to a patient&#39;s leg; 
         FIG. 12A  is a cross-sectional view of an example of a wound dressing pad that may be used in the inventive wound treatment system; and 
         FIG. 12B  is a cross-sectional view of another example of a wound dressing pad that may be used in the inventive wound treatment system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” “top,” “bottom,” and derivatives thereof shall relate to the invention as shown in the drawings. However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices illustrated in the attached drawings and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions, proportions, and other physical characteristics relating to the embodiment disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     As shown in  FIGS. 1A and 1B , a system is provided for treatment of wounds that includes an electronically controlled suction regulator  20 . According to a first variation shown in  FIG. 1A , the regulator  20  includes an internal vacuum pump. According to a second variation shown in  FIG. 1B , the regulator  20  that connects to an external vacuum source  40 . Such an external vacuum source may include the built-in central vacuum system of a healthcare facility, central vacuum pump remotely located from the suction regulator, or a separate portable vacuum pump. Such a connection may be via an appropriately configured coupler  25  and a supply hose  26 . This system may be used for numerous health provider procedures and devices. As described further below, this system may have special safety features built in to protect the patient. The term “built-in” vacuum system is intended to refer to vacuum systems that are plumbed into the building structure of a healthcare facility and is not intended to cover a vacuum pump mounted to a wall or other structure of the patient&#39;s room. “Healthcare facility” is intended to include hospitals, outpatient treatment facilities, doctors&#39; offices, nursing homes, and any other facility in which healthcare services are provided. 
     As shown in  FIGS. 1A ,  1 B, and  2 , the system  10  may include electronically controlled suction regulator  20  as a single unit having a housing  22  with integrated regulation of the vacuum and a containment apparatus  80   a  that will contain solids and liquids, but let gaseous materials pass to the atmosphere. The purpose is to provide a safe method of providing either constant or intermittent/modulated vacuum to a physician or health provider for use on a patient or connection to a device that may or may not be used on a patient. This device is electronically controlled and will perform various functions including the ability to lock-out users from changing settings to alarming functions for safety and efficacy. 
     As shown in  FIG. 2 , system  10  may further include a disposable wound dressing  200  for application to a wound site  250  of a patient. As discussed further below, dressing  200  effectively seals the wound site so that a negative pressure may be maintained at the wound site. 
     As shown in  FIG. 2 , electronically controlled suction regulator  20  may comprise any one or more of the following: a vacuum regulator  30  that is either a vacuum pump or is otherwise connected to either the vacuum system  40  of the healthcare facility or an external portable vacuum pump; a valve or valve type system  50  (such as an electronically controlled three-way solenoid valve or a pneumatic valve) connected to vacuum regulator  30 ; a control circuit  60  powered by electrical current for controlling various components of the regulator and for generating control signals for controlling valve  50  so that the source of vacuum supplied to a patient or device for predetermined periods of time is able to deliver constant or intermittent vacuum; a flow sensor  70 , such as a pressure transducer, connected to control circuit  60  for monitoring the negative pressure applied to a patient or device; a canister/basin  80   a  for collecting fluids drained from the patient&#39;s wound; an optional second canister/basin  80   b  for collecting additional fluids drained from the patient&#39;s wound; and an optional transmitter or transceiver  90  for transmitting information to a healthcare facility database  100  via an optional receiver or transmitter  110 . 
     The source of vacuum may have a vacuum between 0 and 600 mmHg, and may be either vacuum pump internal to housing  22  or an external vacuum system  40  built into a healthcare facility, such as a distributed hospital vacuum system. The vacuum from system  40  may be regulated by vacuum regulator  30  operating under control of control circuit  60  and may be selectively applied continuously or intermittently or may be interrupted by valve  50 . The application of negative pressure to the wound site  250  can be actuated at predetermined time intervals or in response to wound site conditions such as an accumulation of fluid under the wound dressing  200 . During an intermittent vacuum mode the apparatus may vent to the ambient atmosphere or supply low pressure oxygen to the wound during vacuum off time. 
     As shown in  FIG. 3 , control circuit  60  may comprise a programmable digital processor  120  and a liquid crystal display or similar technology display panel  130  connected to the other electronic circuitry. Control circuit  60  may further include an end user interface  140  such as a touch pad with one or more switches, connected to processor  120 . Processor  120  may be programmable to turn the electronics on and off at prescribed times. In addition, end user interface may be configured to allow an end user to select various settings that may be employed to adjust the characteristics (i.e., timing cycle, intermittent mode, continuous mode, pressure, etc.) of the suction produced at the output of suction regulator  20 . In addition, The electronically controlled suction regulator may provide the ability to lock out negative pressure settings so that the patients cannot change settings by the healthcare providers. 
     Suction regulator  20  may further comprise a rechargeable battery  160  and a main power switch coupled in series with the control circuit  60  so as to selectively power the portable device. Regulator  20  may also include a pair of terminals for connection to a 12 VDC input for charging the battery. Control circuit  60  may include an AC to DC converter and regulating circuitry that may be connected to these terminals such that regulated DC power is supplied to the electronic circuitry and the battery  160 . 
     Canister/basin  80   a  may have an adjustable proximity switch connected to processor  120  for generating an audible using a noise emitter  150  and/or a visual alarm using an LED or LCD  130  to indicate that the contents have reached a particular level. Canister/basin  80   a  may be used with a ‘gel pack’ and or a porous filter. Preferably, canister/basin  80   a  includes he fluid level sensor disclosed in U.S. patent application Ser. No. 12/262,474, entitled “FLUID LEVEL SENSOR FOR A CONTAINER OF A NEGATIVE PRESSURE WOUND TREATMENT SYSTEM,” filed on Oct. 31, 2008 by Albert A. Schenk III et al., the entire disclosure of which is incorporated herein by reference. 
     Housing  22  and canister  80   a  may be made from polymers for light weight and impact resistance. Further, canister/basin  80   a  may be replaceable and thus disposable and may contain about 250-1500 ml. Canister/basin  80   a  may be removable and may be sealed with a gasket, o-ring, or similar sealing apparatus. Canister/basin  80   a  may be frosted to obstruct portions of view but is clear in specific areas  180  to view contents and compare to a scale such as but not limited to ml. Canister/basin  80   a  may be a portion less than a ¾ circle but more than a ¼ circle and may be keyed to fit the unit  20  with an integral incorporated into basis conduit/hose with a press fit cradle. 
     Electronically controlled suction regulator  20  may thus comprise a safe regulation system with integrated (basin/canister/reservoir) and device for preventing liquids from leaving the (basin/canister/reservoir) thus containing possible contaminates. Further, the electronically controlled suction regulator may comprise integrated electronics that will regulate between 0 and 600 mmHg and provide ability to modulate/intermittent between negative pressure and atmospheric pressure. The electronically controlled suction regulator may have a mechanical method for determining fluid level in canister  80   a  and the ability to stop the vacuum. 
     Although the application described herein of suction regulator  20  is that of negative pressure wound treatment (NPWT), suction regulator  20  may be used in a variety of applications. The electronically controlled suction regulator is well-suited for use in healthcare facilities as a general safe method of filtering and regulating reduced pressure for procedures such as but not limited to: nasopharyngeal, tracheal, surgical, gastrointestinal, pleural, wound drainage, etc. The features that make suction regulator  20  uniquely suited for NPWT is its ability to: (1) allow end user adjustment of the output suction characteristics (i.e., timing cycle, intermittent mode, continuous mode, pressure, etc.), (2) generate an alarm if fluid in a canister reaches a particular level, and (3) generate an alarm if the flow rate from the wound is too high (above a threshold level), which indicates a leak. 
     The electronically controlled suction regulator  20  may be hung on a wall using preexisting brackets or may be placed on a bed using a clamp or pole, or be free standing with and without an optional base and an IV pole. 
     A filter/fluid trap that is permeable by gas only and not permeable by solids or liquids may be interposed between the vacuum source and the canister/basin to prevent solids or liquids from being introduced into the regulator system, the conduits, or the vacuum source. The filter may be a porous polymer that impedes solids and liquids from passing but allows gaseous materials to pass. The filter may be a polymer or other natural substance. The filter may be single or plural but may cover all conduits exiting reservoir/canister. An outlet conduit for fluid may be connected between an outlet port of the canister and the vacuum source, and the filter may be disposed in the canister substantially at the interface between the outlet port and the outlet conduit. 
     A first pressure detector may be provided that is adapted to detect a pressure drop indicative of the filter being substantially covered/blocked by water or solids. 
     The suction regulator may further comprise an optional negative pressure detector disposed in the inlet conduit that may compare the measured pressure with a preset level to determine if the negative pressure/vacuum is at or above the preset pressure level. This system will work with a single conduit/tube and can aid in prevention of blockage without need for separate detection systems. 
     The suction regulator electronics may be configured to time stamp the proximity switches position by operator. As explained further below, such time stamps and switch positions may be supplied to the healthcare facility&#39;s records database. 
     The electronics logic may be configured to protect patients by alarming if too much fluid is contained in the canister in a pre-entered time frame. 
     According to one embodiment of the present invention, the regulator system  10  is used for applying a negative pressure to a wound. This may be accomplished by connecting the outlet conduit of the suction regulator  20  to the patient interface portion  200  of the systems disclosed in U.S. Pat. Nos. 4,382,441, 4,392,858, 4,655,754, 4,826,494, 4,969,880, 5,100,396, 5,261,893, 5,527,293, 5,636,643, 5,645,081, 6,071,267, 6,117,111, 6,135,116, 6,142,982, 6,174,306, 6,345,623, 6,398,767, 6,520,982, 6,553,998, 6,814,079, 7,198,046, and 7,216,651, the entire disclosures of which are incorporated herein by reference. 
       FIGS. 4-12B  relate to disposable wound dressings  200  that may be used in the inventive system. The disposable wound dressings shown in  FIGS. 4-12B  are described below.  FIGS. 4-7  show an example of one wound treatment system to which the various improvements may be implemented separately or in various combinations.  FIG. 4  is a perspective view of a disposable wound dressing  200 . Disposable wound dressing  200  includes wound drape  222  that includes an interior portion  224  surrounded by a perimeter  226 . Drape  222  further includes a skin contact surface  228  with an adhesive coating  230 . The drape may be made of membrane permeable, semi-permeable or non-permeable materials that are commercially available, an example being material referred to as TAGODERM®, which is available from the 3M (Minnesota Mining and Manufacturing) Company of St. Paul, Minn. A protective backing  223  is placed over the adhesive coating  230  on the skin contact surface  228  until drape  222  is ready for application. 
     Wound drape  222  may comprise a pair of panels  219  with inner, upturned edges  220  which can be adhesively joined together to form a seam  221  which extends transversely across drape  222  and projects generally upwardly therefrom. The panels  219  can be secured together at the seam  221  by the adhesive coating  230  to form the seam  221 . Alternatively, drape  222  may be made of a single panel as described further below. 
     The vacuum conduit may include a tube or sheath  234  that includes a proximate end  36  located under drape  222  and a distal or free end  238 . The tube  234  can be inserted through the seam  21  which forms an opening  232  between the panel edge strips  220  at approximately the center of the drape  222 . If a single panel  219  is used such that no seam is present, a hole may be formed in the drape  222  for passage of the tube or for placement of an attachment pad or coupler (discussed below). A relatively short length of the tube  234  adjacent to its proximate end  236  is shown under the drape  222  in  FIG. 5 , but greater lengths of the tube  234  could be placed under the drape  222 . As shown in  FIG. 7 , the tube proximate end  36  is open, and adjacent to the proximate end  236  one or more openings are formed. The tube opening(s)  239  may project downwardly, i.e. away from the skin contact surface  228 . The short length of the tube  234 , which is located under drape  222 , can be releasably secured to the skin contact surface  228  by the adhesive coating  230 , preferably with the tube opening  239  facing downwardly. The tube  234  may have a length that is sufficient to extend to the vacuum source  242  or to the containment apparatus  241 . Alternatively, a second tube may be attached to the free end  238  of the tube  234 . 
     The tube  234  can comprise, for example, a flexible, plastic tube of the type that is commonly used as a percutaneous sheath for intravenous treatments. At its distal end  238 , the tube  234  may be adapted for: (1) closure with a variety of suitable closure devices; (2) connection to various active and passive fluid collection devices for draining and evacuating fluid from the wound site; and (3) connection to various fluid source devices for actively and passively introducing fluid to the wound site. 
       FIG. 5  shows the tube distal end  238  fluidically communicating with a suction regulator  20  for actively draining fluid from the wound site. 
     The disposable wound dressing  200  may further include a wound dressing pad  225  between the wound site  250  and drape  222 . The wound dressing pad  225  can comprise a variety of materials with varying properties such as: (1) absorbency; (2) wicking or capillary action; and (3) surface contact action. The wound dressing  225  is primarily located in a chamber  246  formed between the wound  250  and the drape  222 . 
     In wound treatment systems such as the one described above, the wound dressing pad  225  is sized and shaped to fit in and over the wound to be treated, and thus the wound dressing is in direct contact with the wound. In prior systems, a gauze or foam is used as the wound dressing pad so as to allow air to flow around the wound. The air flow is caused by the application of a vacuum. Because the vacuum also tends to draw fluids from the wound and through the wound dressing pad, the wound tissue can grow into the wound dressing pad or otherwise stick to the wound dressing pad. This causes problems in that the wound does not heal properly and can also reopen when the wound dressing is removed or changed. In addition, the removal of a wound dressing pad that is stuck to the wound, can be particularly uncomfortable for the patient. 
     Wound dressing pad  25  may be siliconized to allow tissue on and around the wound to form without growing into or onto the wound dressing pad or from otherwise sticking to the wound tissue. The wound dressing pad may include a support material such as a natural fiber, polymer, foam (such as a granufoam-urethane base or whitefoam-PVA base), or other filler/support material. An example of a foam is a granufoam available from Kinetic Concepts, Inc. (KCI) of San Antonio, Tex. The filler/support material could be “siliconized.” This can occur by at least partially covering the support material with silicone which can be accomplished by applying silicone to at least the surface of the filler/support material that directly contacts the wound, by impregnating the filler/support material with silicone, or by using a filler/support material that already integrally includes silicone or its equivalent. By using silicone or an equivalent, the wound can properly heal without the wound tissue growing into or sticking to the wound dressing pad. One commercially available material that may be used as the wound dressing is THERAGAUZE®, which is available from Soluble Solutions, LLC of Newport News, Va. The formulation of THERAGAUZE® is believed to be disclosed in U.S. Pat. No. 6,592,860, the entire disclosure of which is incorporated herein by reference. Alternatively, one may use foam that is seared to close cells on the foam surface adjacent the wound, or use a dual-density foam (two styles of foam together for different end effects) as shown in  FIGS. 12A and 12B . Specifically, the dual density foam pad  225  includes a larger cell foam layer  225   a  and a smaller cell foam layer  225   b  that contacts the wound. As shown in  FIG. 12B , the foam pad  225  may further include an optional coating  225   c  of a material such as silicone. 
     The silicone/seared foam may or may not be perforated or slit to allow vacuum, ambient or a positive pressure to pass through, and to allow liquids to pass. Whether to perforate or slit the silicone will depend upon the particular application and the nature of the filler/support material and how the silicone is provided. 
     The siliconized wound, seared, dual-density dressing pads  225  may be coated with a medicated or non-medicated solution such as polypropylene, glycol and saline, silver, an anti-bacterial solution or the like, that may promote healing and/or reduce adhesion of tissue and fluids. 
     Alternatively, wound dressing pad  225  is made of a bio-absorbable material such that wound tissue growth into pad  225  because a positive condition rather than a negative condition as the pad may simply be left in place into the patient&#39;s body absorbs the pad. 
     The wound drape  222  may be any conventional drape material known to be used for vacuum-assisted wound treatment. The material may be a semi-permeable or impermeable flexible covering that may or may not have a valve/relief to the outside atmosphere. The wound drape may have one or more apertures for allowing a tube, attachment pad, or other coupler to be inserted for connection of the vacuum conduit and application of the vacuum to the wound. The application of the vacuum may be regulated and varied during a course of treatment. In addition, the vacuum may be intermittently applied. 
     The system may use a tube that has a plurality of apertures through its sidewalls at the end of the tube that extends into and under the wound drape. The end of the tube may lie between the drape and the wound dressing or it may extend into the wound dressing. 
     An attachment pad/coupler has been developed that includes pressure verification mechanism that may be a mechanical device to provide a visual acknowledgement of vacuum at a predetermined pressure level at or near the wound site. In general, an attachment pad/coupler  300  such as that shown in  FIGS. 8-11 , comprises a flange portion  330  having a tapered edge  331 , and a profile which may be of any desired shape. On the face of the flange  330  that intended for contact with the wound dressing pad  225  are one or more projections  332 . The purpose of these projections is to provide one or more fluid channels  333  facilitating the flow of fluids form any point of the flange to a central aperture  334 , from which it is intended to apply suction. The attachment pad  300  includes a connector  335 , located above the aperture  334 , having a tubular end  336  adapted for receiving and connecting to the vacuum conduit. The tubular and may have an outwardly tapered portion to facilitate feeding a tube into the connector. The upper surface  337  of the attachment pad  300  has a substantially smooth surface with the exception of at least one bubble or dome  340  (described further below). Linear attachment may be used in lieu of the attachment pad/coupler. 
     In use, the connector portion  335  is sized so that it extends through the aperture  325  in the wound drape  222  shown in  FIGS. 9 and 10 , with the adhesive surface around the aperture bonded to the smooth surface  337  of the flange  330 . The flange  330  of the attachment pad  300  may be circular as shown in  FIG. 11 . Alternatively, the flange may be any other shape. 
       FIGS. 10 and 11  show the attachment pad  300  attached to a wound site  250  of a patient  370 . The attachment pad  300  is pressed into firm contact with wound dressing pad  225 , which is itself pressed into contact with a wound area  250 . The attachment pad  300  and wound dressing pad  225  are pressed into contact with the wound area by a wound drape  222 . The adhesive surface  330  of drape  222  is bonded to the patient&#39;s skin outside the periphery of the wound dressing pad  225  and attachment pad  300 . It is also bonded to upper surface  337  of the attachment pad  300 . Aperture  325  is formed in the drape  222  to permit the connector portion  335  to extend upwardly through the drape. 
     As mentioned above, attachment pad  300  has at least one convex bubble or dome  340  formed in one of its surfaces, that is sucked inward increasing vacuum pressure at our near the wound site  250 . The size, thickness, and material used for the bubble or dome could be used to calculate an approximate vacuum recognition that would be changeable in the mold itself. The attachment pad  300  could include multiple bubbles that each indicating different vacuum levels such as 50, 100, and 150 mm Hg. 
     An attachment pad such as those disclosed in U.S. Pat. Nos. 6,345,623, 6,553,998, and 6,814,079 may also be used with the inventive system. In addition, a TRACKPAD™ available from KCI may also be employed. 
     As noted above, the wound treatment system  10  may include two canisters  80   a  and  80   b  ( FIG. 2 ). Existing systems use a single canister that has an alarm that is triggered when the canister becomes full. When the canister becomes full, the vacuum system is stopped until the healthcare professional overseeing the treatment of the patient, can get to the room, remove and empty the canister, return the canister, and restart the system. All of this takes time and interrupts the procedure. By using two canisters, a first canister can be used in the normal course, and when the alarm is generated, a signal is sent to an electronically controlled valve that diverts the flow of fluid from the first canister  80   a  to the second canister  80   b  to thereby allow uninterrupted use. When the alarm is generated indicating the first canister  80   a  is full, the healthcare professional overseeing the treatment of the patient, can empty the first canister as was done previously, except that the system can keep operating with the fluid flowing to the second canister  80   b . Upon returning the empty first canister  80   a , the system can either automatically return the flow of fluid to the first canister  80   a  or continue the flow of fluid to the second canister  80   b  until such time that it becomes full—at which time the valve may be reactuated to divert the flow to first canister  80   a.    
     The level of fluid in the canisters  80   a ,  80   b  may be monitored using a continuity sensor that includes two electrically conductive terminals spaced apart at the upper internal region of the canisters such that current flows from one terminal to the other only when the fluid level reaches the terminals thereby causing an alarm. 
     Flow sensor  70  may be used to monitor the pressure of the vacuum and determines if a predetermined start up pressure lasts for a certain time. This feature (also known as “wound close technology”) allows one to monitor the progression of the wound to closure. This can be displayed on display screen  130  and would work as an initial start cycle function that can be done at a new wound site, change of dressing, or as a special cycle that will work when the wound site is at ambient/atmospheric pressure. 
     A venting mechanism may be provided at the attachment pad, in the suction regulator or elsewhere that allows oxygen from ambient air to be vented to the wound at 1 or 2 psi whenever the vacuum is in an off interval of an intermittent cycle or the vacuum is removed. Alternately, an oxygen source may be provided to supply oxygen during such off periods. The venting mechanism may comprise valve  50 , which can be selectively controlled to alternatingly connect either vacuum regulator  30  or ambient air (or an oxygen source) to the wound dressing. 
     The system may also be configured to a high flow (leak detection) alarm that is activated when the flow of air from the wound site is above a threshold. 
     Referring back to  FIG. 2 , optional transmitter/transceiver  90  may be provided to transmit information to a receiver/transceiver  110  that receives the information and provides it to an automated records database  100  of the healthcare facility. The information may include any one or more of the following: the times at which negative pressure was applied to the wound, the pressure applied, the intermittence cycles, the times at which the settings were changed along with the new settings, leak detection alarm times, full canister alarms times, and readings from flow sensor  70  which allows one to monitor the progression of the wound to closure. Transmitter/transceiver  90  may be coupled wirelessly or by wired connection such as USB. The database  100  may be a database such as a Cerner records database. 
     Each of the above-noted features may be implemented separately from the other features, or in combination with one or more of the other features. 
     The above description is considered that of the preferred embodiments only. Modification of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents.