System for providing continual drainage in negative pressure wound therapy

<u>BACKGROUND</u>

1.

Technical Field

0001The present disclosure relates generally to treating a wound with negative or reduced pressure. In particular, the disclosure relates to a system for providing continual drainage of fluids from a wound site to a collection canister.

2.

Background of Related Art

0002Various techniques to promote healing of a wound involve providing suction to the wound. For example, a vacuum source may serve to carry wound exudates away from the wound, which may otherwise harbor bacteria that inhibit the body's natural healing process. One particular technique for promoting the body's natural healing process may be described as negative pressure wound therapy (NPWT). This technique involves the application of a reduced pressure, e.g. subatmospheric, to a localized reservoir over a wound. Subatmospheric pressure has been found to assist in closing the wound by promoting blood flow to the area, thereby stimulating the formation of granulation tissue and the migration of healthy tissue over the wound. This technique has proven effective for chronic or non-healing wounds, but has also been used for other purposes such as post-operative wound care.

0003<patcit id="pcit0001" dnum="EP1919533A"><text>EP1919533</text></patcit> discloses a suctioning system, method and kit.

0004The general NPWT protocol provides for covering the wound with a flexible cover layer such as a polymeric film, for example, to establish a vacuum reservoir over the wound where a reduced pressure may be applied by individual or cyclic evacuation procedures. wound where a reduced pressure may be applied by individual or cyclic evacuation procedures. To allow the reduced pressure to be maintained over time, the cover layer may include an adhesive periphery that forms a substantially fluid tight seal with the healthy skin surrounding the wound.

0005Although some procedures may employ a micro-pump contained within the vacuum reservoir, most NPWT treatments apply a reduced pressure using an external vacuum source. Fluid communication must therefore be established between the reservoir and the vacuum source. To this end, a fluid port is coupled to the cover layer to provide an interface for an exudate conduit extending from the external vacuum source. Fluid being drained from the reservoir through the exudate conduit tends to stagnate with slow fluid buildup. This stagnation results in interrupted and/or incomplete fluid drainage. Accordingly, it would be beneficial to have a negative pressure wound therapy system that included a controlled or fixed "leak" to provide for continuous and/or complete fluid drainage.

<u>SUMMARY</u>

0006A system for subatmospheric pressure therapy in connection with healing a wound is provided. The system includes a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system further includes an exudate conduit in fluid communication with the wound dressing and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum source and a vent conduit in fluid communication with the collection canister and the wound dressing for introducing air into the reservoir to facilitate flow of exudate through the exudate conduit.

0007The vent conduit may define an internal dimension less than a corresponding internal dimension of the exudate conduit. The exudate conduit and the vent conduit may include independent tube segments, or instead may include integral tube segments. A filter may be in fluid communication with the vent conduit. The filter includes a hydrophobic material. The filter may instead or additionally include a bacterial filter.

0008Also provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system further includes an exudate conduit in fluid communication with the wound dressing and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum source and a vent mounted to the wound dressing, the vent being selectively movable between a closed position and an open position, the vent permitting ingress of air within the reservoir when in the open position.

0009The vent may include a flap mounted to the wound dressing cover, the flap being movable between the closed position and the open position. The flap may be releasably securable in the closed position with an adhesive. A filter membrane may be mounted adjacent the flap. The filter membrane may include a hydrophobic material. The filter membrane may instead or additionally include a bacterial filter.

0010Additionally, provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system further includes an exudate conduit in fluid communication with the wound dressing and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum source and a filtered air vent mounted to the wound dressing cover, the filtered air vent adapted to permit ingress of air within the reservoir to facilitate flow of exudate through the exudate conduit.

0011Additionally, provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system also includes a wound port operatively connected to the wound dressing in fluid communication with the reservoir. The wound port includes a vacuum port and at least one tube piercing through the wound port into the reservoir, the tube being operable to allow ambient air into the reservoir. The system further includes an exudate conduit in fluid communication with the wound port and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum.

0012Additionally, provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system also includes a wound port operatively connected to the wound dressing in fluid communication with the reservoir. The wound port includes a vacuum port and a plurality of holes arranged circumferentially around the wound port, the plurality of holes being operable to allow ambient air into the reservoir. The system further includes an exudate conduit in fluid communication with the wound port and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum.

0013Additionally, provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system also includes a wound port operatively connected to the wound dressing in fluid communication with the reservoir. The wound port includes a vacuum port and an orifice being operable to allow ambient air into the reservoir. The system further includes an exudate conduit in fluid communication with the wound port and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum.

0014Additionally, provided is a system for subatmospheric pressure therapy in connection with healing a wound including a wound dressing cover dimensioned for positioning relative to a wound bed of a subject to establish a reservoir over the wound bed in which subatmospheric pressure may be maintained, a subatmospheric pressure mechanism including, a housing, a vacuum source disposed in the housing, and a collection canister in fluid communication with the vacuum source. The system also includes a wound port operatively connected to the wound dressing in fluid communication with the reservoir. The system further includes an exudate conduit in fluid communication with the wound port and the collection canister for collecting exudate removed from the reservoir and deposited in the collection canister under influence of the vacuum. The exudate conduit has a first conduit for providing a pathway for the exudate between the reservoir and the collection canister and a second conduit in fluid communication with ambient atmosphere and the wound dressing for introducing air into the reservoir to facilitate flow of exudate through the exudate conduit.

<u>BRIEF DESCRIPTION OF THE DRAWINGS</u>

0015The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure. <ul id="ul0001" list-style="none"><li><figref idref="f0001">FIG. <b>1</b></figref> depicts an embodiment of a NPWT system in accordance with the present disclosure;</li><li><figref idref="f0002">FIG. <b>2</b></figref> depicts an embodiment of an NPWT treatment apparatus including a vent conduit;</li><li><figref idref="f0003">FIG. <b>3</b>A</figref> is a partial cross sectional view of the conduits of the NPWT treatment apparatus of <figref idref="f0001">FIGS. <b>1</b></figref> and <figref idref="f0002"><b>2</b></figref> connected in an alternate configuration;</li><li><figref idref="f0003">FIG. <b>3</b>B</figref> is a partial cross sectional view of an alternative embodiment of the fluid port of <figref idref="f0001">FIGS. <b>1</b></figref> and <figref idref="f0002"><b>2</b></figref>;</li><li><figref idref="f0004">FIG. <b>4</b></figref> is a cross sectional view of an alternative embodiment of the wound dressing in accordance with the present disclosure;</li><li><figref idref="f0005">FIGS. <b>5</b>A and <b>5</b>B</figref> depict alternative embodiments of the wound dressing in accordance with the present disclosure;</li><li><figref idref="f0006">FIGS. <b>6</b>A and <b>6</b>B</figref> depict alternative embodiments of the wound dressing in accordance with the present disclosure;</li><li><figref idref="f0007">FIGS. <b>7</b>A and <b>7</b>B</figref> depict alternative embodiments of the wound dressing in accordance with the present disclosure;</li><li><figref idref="f0008">FIGS. <b>8</b>A and <b>8</b>B</figref> depict alternative embodiments of the wound dressing in accordance with the present disclosure;</li><li><figref idref="f0009">FIG. <b>9</b></figref> depicts an alternative embodiment of the wound port in accordance with the present disclosure;</li><li><figref idref="f0009">FIGS. <b>10</b>A and <b>10</b>B</figref> depict alternative embodiments of the wound port in accordance with the present disclosure; and</li><li><figref idref="f0010 f0011">FIGS. <b>11</b>A-<b>11</b>D</figref> depict alternative embodiments of the wound port in accordance with the present disclosure.</li></ul>

<u>DETAILED DESCRIPTION OF EMBODIMENTS</u>

0016Various embodiments of the present disclosure provide negative pressure wound therapy systems (or apparatus) including a collection canister having a chamber to collect wound fluids. Embodiments of the presently disclosed negative pressure wound therapy systems are generally suitable for use in applying negative pressure to a wound to facilitate healing of the wound in accordance with various treatment modalities. Embodiments of the presently disclosed negative pressure wound therapy systems are entirely portable and may be worn or carried by the user such that the user may be completely ambulatory during the therapy period. Embodiments of the presently disclosed negative pressure wound therapy apparatus and components thereof may be entirely reusable or may be entirely disposable after a predetermined period of use or may be individually disposable whereby some of the components are reused for a subsequent therapy application.

0017Hereinafter, embodiments of the presently disclosed negative pressure wound therapy systems and embodiments of the presently disclosed sensors for use in negative pressure wound therapy systems will be described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures. As used herein, "wound exudate", or, simply, "exudate", generally refers to any fluid output from a wound, e.g., blood, serum, and/or pus, etc. As used herein, "fluid" generally refers to a liquid, a gas or both.

0018Referring to <figref idref="f0001">FIG. <b>1</b></figref>, a NPWT apparatus according to an embodiment of the present disclosure is depicted generally as <b>10</b> for use on a wound bed <b>"w"</b> surrounded by healthy skin <b>"s"</b>. Negative pressure wound therapy apparatus <b>10</b> includes a wound dressing <b>12</b> positioned relative to the wound bed <b>"w"</b> to define a vacuum chamber <b>14</b> about the wound bed <b>"w"</b> to maintain negative pressure at the wound area. Wound dressing <b>12</b> includes a contact layer <b>18</b>, a wound filler <b>20</b> and a wound cover <b>24.</b>

0019Contact layer <b>18</b> is intended for placement within the wound bed <b>"w"</b> and may be relatively non-supportive or flexible to substantially conform to the topography of the wound bed <b>"w".</b> A variety of materials may be used for the contact layer <b>18.</b> Contact layer <b>18</b> selection may depend on various factors such as the patient's condition, the condition of the periwound skin, the amount of exudate and/or the condition of the wound bed <b>"w".</b> Contact layer <b>18</b> may be formed from perforated film material. The porous characteristic of the contact layer <b>18</b> permits exudate to pass from the wound bed <b>"w"</b> through the contact layer <b>18</b>. Passage of wound exudate through the contact layer <b>18</b> may be substantially unidirectional such that exudate does not tend to flow back into the wound bed <b>"w".</b> Unidirectional flow may be encouraged by directional apertures, e.g., apertures positioned at peaks of undulations or cone-shaped formations protruding from the contact layer <b>18.</b> Unidirectional flow may also be encouraged by laminating the contact layer <b>18</b> with materials having absorption properties differing from those of the contact layer <b>18</b>, or by selection of materials that promote directional flow. A non-adherent material may be selected for forming the contact layer <b>18</b> such that the contact layer <b>18</b> does not tend to cling to the wound bed <b>"w"</b> or surrounding tissue when it is removed. One example of a material that may be suitable for use as a contact layer <b>18</b> is commercially available under the trademark XEROFLOW® offered by Tyco Healthcare Group LP (d/b/a Covidien). Another example of a material that may be suitable for use as the contact layer <b>18</b> is the commercially available CURITY® non-adherent dressing offered by Tyco Healthcare Group LP (d/b/a Covidien).

0020Wound filler 20 is positioned in the wound bed <b>"w"</b> over the contact layer <b>18</b> and is intended to transfer wound exudate. Wound filler <b>20</b> is conformable to assume the shape of any wound bed "w" and may be packed up to any level, e.g., up to the level of healthy skin <b>"s"</b> or to overfill the wound such that wound filler <b>20</b> protrudes over healthy skin <b>"s".</b> Wound filler <b>20</b> may be treated with agents such as polyhexamethylene biguanide (PHMB) to decrease the incidence of infection and/or other medicaments to promote wound healing. A variety of materials may be used for the wound filler <b>20</b>. An example of a material that may be suitable for use as the wound filler <b>20</b> is the antimicrobial dressing commercially available under the trademark KERLIX™ AMD™ offered by Tyco Healthcare Group LP (d/b/a Covidien).

0021Cover layer <b>24</b> may be formed of a flexible membrane, e.g., a polymeric or elastomeric film, which may include a biocompatible adhesive on at least a portion of the cover layer <b>24</b>, e.g., at the periphery <b>26</b> of the cover layer <b>24</b>. Alternately, the cover layer <b>24</b> may be a substantially rigid member. Cover layer <b>24</b> may be positioned over the wound bed <b>"w"</b> such that a substantially continuous band of a biocompatible adhesive at the periphery <b>26</b> of the cover layer <b>24</b> forms a substantially fluid-tight seal with the surrounding skin <b>"s"</b>. An example of a material that may be suitable for use as the cover layer <b>24</b> is commercially available under the trademark CURAFORM ISLAND^® offered by Tyco Healthcare Group LP (d/b/a Covidien).

0022Cover layer <b>24</b> may act as both a microbial barrier and a fluid barrier to prevent contaminants from entering the wound bed <b>"w"</b> and to help maintain the integrity thereof.

0023In one embodiment, the cover layer <b>24</b> is formed from a moisture vapor permeable membrane, e.g., to promote the exchange of oxygen and moisture between the wound bed <b>"w"</b> and the atmosphere. An example of a membrane that may provide a suitable moisture vapor transmission rate (MVTR) is a transparent membrane commercially available under the trade name POLYSKIN® II offered by Tyco Healthcare Group LP (d/b/a Covidien). A transparent membrane may help to permit a visual assessment of wound conditions to be made without requiring removal of the cover layer <b>24.</b>

0024Wound dressing <b>12</b> may include a vacuum port <b>30</b> having a flange <b>34</b> to facilitate connection of the vacuum chamber <b>14</b> to a vacuum system. Vacuum port <b>30</b> may be configured as a rigid or flexible, low-profile component and may be adapted to receive a conduit <b>36</b> in a releasable and fluid-tight manner. An adhesive on at least a portion of the underside of the flange <b>34</b> may be used to provide a mechanism for affixing the vacuum port 30 to the cover layer <b>24</b>. The relative positions, size and/or shape of the vacuum port <b>30</b> and the flange <b>34</b> may be varied from an embodiment depicted in <figref idref="f0001">FIG. <b>1</b></figref>. For example, the flange <b>34</b> may be positioned within the vacuum chamber <b>14</b> such that an adhesive on at least a portion of an upper side surface of the flange <b>34</b> affixes the vacuum port <b>30</b> to the cover layer <b>24</b>. A hollow interior portion of the vacuum port <b>30</b> provides fluid communication between the conduit <b>36</b> and the vacuum chamber <b>14</b>. Conduit <b>36</b> extends from the vacuum port <b>30</b> to provide fluid communication between the vacuum chamber <b>14</b> and the vacuum source <b>40</b>. Alternately, the vacuum port <b>30</b> may not be included in the dressing <b>12</b> if other provisions are made for providing fluid communication with the conduit <b>36</b>.

0025Any suitable conduit may be used for the conduit <b>36</b>, including conduit fabricated from flexible elastomeric or polymeric materials. In the negative pressure wound therapy apparatus <b>10</b> illustrated in <figref idref="f0001">FIG. <b>1</b></figref>, the conduit <b>36</b> includes a first conduit section <b>36</b>A, a second conduit section <b>36</b>B, a third conduit section <b>36</b>C and a fourth conduit section <b>36</b>D. The first conduit section <b>36</b>A extends from the vacuum port <b>30</b> and is coupled via a fluid line coupling <b>100</b> to the second conduit section <b>36</b>B<b>,</b> which extends to the collection canister <b>38</b>. The third conduit section <b>36</b>C extends from the collection canister <b>38</b> and is coupled via another fluid line coupling <b>100</b> to the fourth conduit section <b>36</b>D, which extends to the vacuum source <b>40</b>. The shape, size and/or number of conduit sections of the conduit <b>36</b> may be varied from the first, second, third and fourth conduit sections <b>36</b>A, <b>36</b>B, <b>36</b>C and <b>36</b>D depicted in <figref idref="f0001">FIG. <b>1</b></figref>.

0026The first, second, third and fourth conduit sections <b>36</b>A, <b>36</b>B, <b>36</b>C and <b>36</b>D of the conduit <b>36</b> may be connected to components of the apparatus <b>10</b> by conventional air-tight means, such as, for example, friction fit, bayonet coupling, or barbed connectors. The connections may be made permanent. Alternately, a quick-disconnect or other releasable connection means may be used to provide some adjustment flexibility to the apparatus <b>10</b>.

0027Collection canister <b>38</b> may be formed of any type of container that is suitable for containing wound fluids. For example, a semi-rigid plastic bottle may be used for the collection canister <b>38</b>. A flexible polymeric pouch or other hollow container body may be used for the collection canister <b>38</b>. Collection canister <b>38</b> may contain an absorbent material to consolidate or contain the wound fluids or debris. For example, super absorbent polymers (SAP), silica gel, sodium polyacrylate, potassium polyacrylamide or related compounds may be provided within collection canister <b>38</b>. At least a portion of canister <b>38</b> may be transparent or semi-transparent, e.g., to permit a visual assessment of the wound exudate to assist in evaluating the color, quality and/or quantity of exudate. A transparent or semi-transparent portion of the collection canister <b>38</b> may permit a visual assessment to assist in determining the remaining capacity or open volume of the canister and/or may assist in determining whether to replace the collection canister <b>38</b>.

0028The collection canister <b>38</b> is in fluid communication with the wound dressing <b>12</b> via the first and second conduit sections <b>36</b>A, <b>36</b>B. The third and fourth conduit sections <b>36</b>C, <b>36</b>D connect the collection canister <b>38</b> to the vacuum source <b>40</b> that generates or otherwise provides a negative pressure to the collection canister <b>38</b>. Vacuum source <b>40</b> may include a peristaltic pump, a diaphragmatic pump or other suitable mechanism. Vacuum source <b>40</b> may be a miniature pump or micropump that may be biocompatible and adapted to maintain or draw adequate and therapeutic vacuum levels. The vacuum level of subatmospheric pressure achieved may be in the range of about <b>20</b> mmHg to about <b>500</b> mmHg. In embodiments, the vacuum level may be about <b>75</b> mmHg to about <b>125</b> mmHg, or about <b>40</b> mmHg to about <b>80</b> mmHg. One example of a peristaltic pump that may be used as the vacuum source <b>40</b> is the commercially available Kangaroo PET Eternal Feeding Pump offered by Tyco Healthcare Group LP (d/b/a Covidien). Vacuum source <b>40</b> may be actuated by an actuator (not shown) which may be any means known by those skilled in the art, including, for example, alternating current (AC) motors, direct current (DC) motors, voice coil actuators, solenoids, and the like. The actuator may be incorporated within the vacuum source <b>40</b>.

0029In embodiments, the negative pressure wound therapy apparatus <b>10</b> includes one or more fluid line couplings <b>100</b> that allow for selectable coupling and decoupling of conduit sections. For example, a fluid line coupling <b>100</b> may be used to maintain fluid communication between the first and second conduit sections <b>36</b>A, <b>36</b>B when engaged, and may interrupt fluid flow between the first and second conduit sections 36A, 36B when disengaged. Thus, fluid line coupling <b>100</b> may facilitate the connection, disconnection or maintenance of components of the negative pressure wound therapy apparatus <b>10</b>, including the replacement of the collection canister <b>38.</b> Additional or alternate placement of one or more fluid line couplings <b>100</b> at any location in line with the conduit <b>36</b> may facilitate other procedures. For example, the placement of a fluid line coupling <b>100</b> between the third and fourth conduit sections <b>36</b>C, <b>36</b>D, as depicted in <figref idref="f0001">FIG. <b>1</b></figref>, may facilitate servicing of the vacuum source <b>40</b>.

0030Referring to <figref idref="f0002">FIG. <b>2</b></figref>, an NPWT apparatus similar to the NPWT apparatus of <figref idref="f0001">FIG. <b>1</b></figref> is depicted generally as <b>10</b> for use on a wound <b>"w"</b> surrounded by healthy skin "s." The NPWT apparatus <b>10</b> of <figref idref="f0002">FIG. <b>2</b></figref> includes a vent conduit <b>37</b> that extends from between contact layer <b>18</b> and cover layer <b>22</b> of wound dressing <b>12</b> to collection canister <b>38.</b> Vent conduit <b>37</b> may be integral formed with wound dressing <b>12.</b> Alternatively, vent conduit <b>37</b> may be inserted between contact layer <b>18</b> and cover layer <b>22</b> by a clinician during application of the wound dressing <b>12</b>, or may have been previously inserted therebetween prior to application. Vent conduit <b>37</b> may be releasably connected to the collection canister <b>38</b> by conventional air-tight means such as friction fit, bayonet coupling, or barbed connectors.

0031Vent conduit 37 is configured to provide a low flow of air from the reservoir <b>14</b> to the collection canister <b>38.</b> Vent conduit <b>37</b> includes a smaller diameter than exudate conduit <b>36</b> and may be formed of any suitable conduit including those fabricated from flexible elastomeric or polymeric materials. An air filter <b>39</b> positioned along the air flow path filters the air flowing from collection canister <b>38</b> to remove any impurities, including bacteria and other infectious material. Filter <b>39</b> may include a hydrophobic material to prevent wetting.

0032In operation, wound dressing <b>12</b> is placed adjacent a wound <b>"w"</b> with the vent conduit <b>37</b> extending from between the contact layer <b>18</b> and the cover layer <b>22.</b> If the vent conduit <b>37</b> is not integral formed with the wound dressing <b>12</b>, the clinician may be required to position the vent conduit <b>37</b> between the layers during application of the wound dressing <b>12</b>. Vacuum source <b>50</b> is then activated to produce a sub-atmospheric pressure in the reservoir <b>14</b> of the wound dressing <b>12</b>. Fluid from the reservoir <b>14</b> is drawn through aperture <b>24</b> in cover layer <b>22</b>, into fluid port <b>30</b> and along exudate conduit <b>36</b> to be deposited in collection canister <b>40</b>. As fluid and other exudates are drawn through exudate conduit <b>36</b>, filtered air is received within the reservoir <b>14</b> of the wound dressing <b>12</b> through the vent conduit <b>37</b>. The low flow filtered air flowing from the collection canister <b>38</b> through the vent conduit <b>37</b>, in combination with the high flow drainage occurring through exudate conduit <b>36</b>, creates a sump action between the reservoir <b>14</b> and the collection canister <b>40.</b> This sump action ensures continuous flow through exudate conduit <b>36,</b> thereby preventing fluid stagnation and its complications. Because of capillary action, fluid from reservoir <b>14</b> only flows through the larger diameter exudate conduit <b>36.</b>

0033With reference now to <figref idref="f0003">FIG. <b>3A</b></figref>, in an alternative embodiment of the present disclosure, a wound dressing <b>112</b> is substantially similar to wound dressing <b>12</b> described hereinabove, and will only be described as relates to the differences therebetween. Wound dressing <b>112</b> includes a cover layer <b>122</b> having a first or fluid aperture <b>124</b> and a second or vent aperture <b>125</b>. A fluid port <b>130</b> is in fluid communication with fluid aperture <b>124</b> and is configured for operable engagement with exudate conduit <b>136</b>. A vent port <b>131</b> is in fluid communication with vent aperture <b>125</b> and is configured for operable engagement with vent conduit <b>137</b>. Fluid and vent ports <b>130</b>, <b>131</b> may be affixed to cover layer <b>122</b> in any suitable manner. Each of fluid and vent port <b>130</b>, <b>131</b> are in fluid communication with collection canister <b>38</b> (<figref idref="f0001">FIGS. <b>1</b></figref> and <figref idref="f0002"><b>2</b></figref>).

0034Wound dressing <b>112</b> operates in substantially the same manner as wound dressing <b>12</b>. When connected to collection canister <b>40</b> and the vacuum source <b>50</b> is activated, the sub-atmospheric pressure produced by the vacuum source <b>50</b> creates a suction that draws fluid from the reservoir <b>114</b>. Vent conduit <b>137</b> provides the reservoir <b>114</b> with a low flow of filtered air to ensure continuous fluid flow through the exudate conduit <b>136</b>.

0035Turning now to <figref idref="f0003">FIG. <b>3B</b></figref>, in another embodiment, wound dressing <b>212</b> is substantially similar to the wound dressings <b>12</b>, <b>112</b> described hereinabove. Wound dressing <b>212</b> includes a cover layer <b>222</b> having a first and second aperture <b>224</b>, <b>225.</b> Positioned adjacent first and second apertures <b>224</b>, <b>225</b> is a fluid/vent port <b>230.</b> Port <b>230</b> is configured to fluidly communicate first aperture <b>224</b> of wound dressing <b>212</b> with collection canister <b>38</b> (<figref idref="f0001">FIGS. <b>1</b></figref> and <figref idref="f0002"><b>2</b></figref>) via exudate conduit <b>236</b>. Port <b>230</b> is further configured to fluidly communicate second aperture <b>225</b> of wound dressing <b>212</b> with collection canister <b>40</b> via vent conduit <b>237</b>. As discussed above, the difference in size between exudate conduit <b>236</b> and vent conduit <b>237</b> results in capillary action that causes fluid to flow only through the larger exudate conduit <b>36</b>.

0036With reference now to <figref idref="f0004">FIG. <b>4</b></figref>, in yet another embodiment, a wound dressing <b>312</b> similar to those described above including a vent assembly <b>340</b> formed in a cover layer <b>322.</b> Vent assembly <b>340</b> includes a filter member <b>342</b> and a flap or cover member <b>344.</b> Filter member <b>342</b> may be integrally formed with, or otherwise affixed to, the cover layer <b>322.</b> In one embodiment, filter member <b>342</b> is secured to the cover layer <b>322</b> with an adhesive. Filter member <b>342</b> is configured to provide reservoir <b>314</b> of wound dressing <b>312</b> with filtered air. To prevent wetting, the filter member <b>342</b> may be hydrophobic. Filter member <b>342</b> may be sized depending on the desired flow therethrough. A larger filter member <b>342</b> would provide a greater amount of airflow; however, if the filter member <b>342</b> is too large, it may reduce the effectiveness of the NWPT.

0037Flap <b>344</b> may be integrally formed with cover layer <b>322.</b> Alternatively, flap <b>344</b> may be releasably secured over filter member <b>342.</b> Flap <b>344</b> may be attached to or separable from cover member <b>322.</b> Flap <b>344</b> may be configured to selectively partially or completely uncover filter member <b>342.</b> In this manner, a clinician may affect the flow of air into the reservoir <b>314.</b> Although shown including flap <b>344</b>, it is envisioned that wound dressing <b>312</b> may be provided with filter member <b>342</b> exposed.

0038In use, wound dressing <b>312</b> is applied to a wound <b>"w"</b> in a conventional manner. Activation of the vacuum source <b>40</b> (<figref idref="f0001">FIGS. <b>1</b></figref> and <figref idref="f0002"><b>2</b></figref><b>)</b> initiates drainage from reservoir <b>314</b> of wound dressing <b>312.</b> At any time prior to or during the drainage process, flap <b>344</b> may be partially or complete pulled back to expose filter member <b>342</b>. As described above, the more of filter member <b>342</b> that is exposed, the greater the possible airflow into reservoir <b>14</b>. The airflow provided to reservoir <b>14</b> through filter member <b>342</b> acts in a manner similar to the sump action described above. In this manner, vent assembly <b>340</b> permits continuous fluid flow through exudate conduit <b>336</b>, thereby preventing fluid stagnation and its complications.

0039With reference to <figref idref="f0005">FIGS. <b>5A</b> and 5B</figref>, in yet another embodiment, a wound port <b>500</b> is shown. Wound port <b>500</b> is suitable for use with the above described wound dressings. Wound port <b>500</b> has a plastic cover <b>510</b> which includes a vacuum port <b>512</b>. In addition to the vacuum port <b>512</b>, the plastic cover <b>510</b> has tube <b>520</b>. Tube <b>520</b> may be made of a small-bore stainless steel or rigid plastic. Tube <b>520</b> is used to provide a controlled or fixed leak by admitting air into the wound dressing. Tube <b>520</b> can be arranged to allow the insertion of tube <b>520</b> into the wound port <b>500</b> so that depth adjustment and placement within the wound packing material is possible as indicated by the arrows in <figref idref="f0005">FIGS. <b>5A</b> and <b>5B</b></figref>. As such, air can be injected into the wound packing material to direct movement of excess exudate toward the vacuum port and out of the wound. Tube <b>520</b> may have a valve (not shown) to adjust the flow rate of air into the wound bed. The valve may be a small needle valve that can be attached to the tube <b>520</b> to allow for infinite adjustment of air flow into the wound dressing.

0040The end of tube <b>520</b> that may be exposed to ambient atmosphere or to a source of air may include a filter 5<b>22</b>. Filter <b>522</b> may be a q-tip like air filter to prevent clogging of the tube and also prevent dirt and other contaminants from entering the wound site. Alternatively, filter <b>522</b> may include a charcoal filter to prevent odor, a hydrophobic filter, or any sintered or porous material. The tip of tube <b>520</b> that is inserted into the wound packing material may be equipped with a puncturing tip <b>524</b> to allow for easier insertion into the wound packing material.

0041With reference to <figref idref="f0006">FIGS. <b>6A</b> and <b>6</b>B</figref>, in yet another embodiment, a wound port 600 is shown. As shown in <figref idref="f0006">FIG. <b>6A</b></figref>, wound port <b>600</b> has tube <b>610</b> in separate locations around a circumference of the wound port <b>600</b>. Each tube may include a punctured tip or a filter as described above. As shown in <figref idref="f0006">FIG. <b>6B</b></figref>, the distance "a" between tube <b>610</b> and tube <b>612</b> may be one distance and the distance "b" between tube <b>610</b> and <b>614</b> may be a distance different the distance "a". On the other hand, the difference between each tube may be similar as in the distance "c" between tube <b>620</b> and <b>622</b> and tube <b>620</b> and <b>624</b>. Although <figref idref="f0006">FIGS. <b>6A</b> and <b>6B</b></figref> show a specific number of tubes, any number of tubes may be arranged outside a circumference of the wound port <b>600</b>.

0042With reference to <figref idref="f0007">FIGS. <b>7</b>A and <b>7</b>B</figref>, in yet another embodiment, a wound port <b>700</b> is shown having a tube <b>710</b> which is similar to the tubes described above. Tube <b>710</b> may be slightly larger in diameter to allow for fluids to enter the wound site. The fluids may include a solution to flush the wound such as saline or it may be an anesthetic to anesthetize the wound area. Tube <b>710</b> may be fitted with valve <b>712</b> to open and close the pathway into the wound site. Additionally, the end of tube <b>710</b> may be fitted wit a luer connector <b>714</b> to create a fluid tight connection with additional tubing, syringes, or any other conduits. Alternatively, instead of a valve, a plug (not shown) could be used to close the luer connector. With reference to <figref idref="f0007">FIG. <b>7</b>B</figref>, a hypodermic needle <b>716</b> may be inserted into tube <b>710</b>. Hypodermic needle <b>716</b> could be used to deliver a solution to a specific area of the wound or it could be used to obtain a sample of blood, exudate or tissue from the wound site.

0043With reference to <figref idref="f0008">FIGS. <b>8</b>A and <b>8</b>B</figref>, in yet another embodiment, a wound port <b>800</b> is shown. Instead of using tubes as described above to allow a controlled or fixed leak, a number of small holes arranged in a circumference around the wound port <b>800</b> may be provided. The holes may take the form of a simple puncture <b>810</b> of a given size as shown in <figref idref="f0008">FIG. <b>8</b>A</figref>. Alternatively, the holes <b>822</b> may be formed in a plate <b>820</b> that is radio frequency (RF) welded to the wound port <b>800</b>.

0044With reference to <figref idref="f0009">FIG. <b>9</b></figref>, in yet another embodiment, a cross section of wound port <b>900</b> is shown. Wound port <b>900</b> is operatively connected to wound dressing <b>910</b> and includes a flange <b>912</b>. Flange <b>912</b> may have a circular or any polygonal shape. A body <b>914</b> is connected to the flange <b>912</b> which is fluidly connected to conduit <b>916</b>. Conduit <b>916</b> leads directly or indirectly to the collection canister. Body <b>914</b> has as small orifice <b>920</b> used to provide a controlled leak into the wound site. The diameter of the orifice <b>920</b> and the pressure difference between the outside of the wound port <b>900</b> and the inside of the wound port <b>90</b> create a controllable air leak into the wound port <b>900</b> via the orifice. The small orifice <b>920</b> can be created in various ways. The orifice <b>920</b> can be integral to the port design, such as a molded in feature. It can be created via post molding micro-piercing into the port using a needle or syringe. Alternatively, assembly or insertion of a small tube that allows for communication of air from outside the wound port <b>900</b> to inside the wound port <b>900</b> can be used to create the orifice <b>920</b>.

0045With reference to <figref idref="f0009">FIGS. <b>10</b>A and <b>10</b>B</figref>, in yet another embodiment, a wound port <b>1000</b> is shown. Wound port <b>1000</b> is operatively connected to wound dressing <b>1010</b> and includes a flange <b>1012</b>. Flange <b>1012</b> may have a circular or any polygonal shape. A body <b>1014</b> is connected to the flange <b>1012</b> which is fluidly connected to conduit <b>1016</b>. Conduit <b>1016</b> leads directly or indirectly to the collection canister. Conduit <b>1016</b> includes a main lumen <b>1110</b> used to provide a pathway for exudate between the wound <b>"w"</b> and the collection canister. A secondary lumen or vent lumen is provided in conduit <b>1016</b> to provide a controlled leak to the wound site. Exudate enters lumen <b>1110</b> at area <b>1114</b> and air exits lumen <b>1112</b> at area <b>1116</b>. Secondary lumen <b>1112</b> is exposed to the ambient environment or to a source of air to provide a controlled leak in the wound port <b>1000.</b> Although <figref idref="f0009">FIG. <b>10</b>B</figref> depicts lumens <b>1110</b> and <b>1112</b> in a single conduit <b>1016</b>, lumens <b>1110</b> and <b>1112</b> can be provided as separate conduits.

0046With reference to <figref idref="f0010">FIG. <b>11</b>A</figref>, in yet another embodiment, a wound dressing <b>1200</b> is shown having a wound port <b>1210</b>. Wound dressing <b>1200</b> and wound port <b>1210</b> are similar to wound dressing <b>12</b>, <b>112</b>, and <b>212</b> and wound port <b>1210</b> are similar to wound port <b>30</b>, <b>130</b> and <b>230</b> described hereinabove. A vent conduit <b>1220</b> may be inserted into the top of wound port <b>1210</b> to provide a source of filtered air into the wound dressing <b>1200</b> through the vent conduit <b>1220</b>. Vent conduit <b>1220</b> may be a stainless steel needle having a lumen extending through the needle. The end of vent conduit <b>1220</b> has filter <b>1225</b> to filter the air from the ambient atmosphere. The low flow filtered air flowing from the ambient atmosphere through the vent conduit <b>1220</b>, in combination with the high flow drainage occurring through an exudate conduit, creates a sump action between the wound and a collection canister. This sump action ensures continuous flow through exudate conduit <b>36</b>, thereby preventing fluid stagnation and its complications. As discussed above, the difference in size between exudate conduit and vent conduit <b>1220</b> results in capillary action that causes fluid to flow only through the larger exudate conduit. <figref idref="f0010 f0011">FIGS <b>11</b>B-<b>11</b>D</figref> depict a wound port <b>1210</b> similar to the wound port in <figref idref="f0010">FIG. <b>11</b>A</figref>. In <figref idref="f0010 f0011">FIGS <b>11</b>B-<b>11</b>D</figref>, the vent conduit <b>1220</b> is placed on the side of the wound port <b>1210</b> rather than the top of the wound port <b>1210</b> as shown in <figref idref="f0010">FIG. 11A</figref>. <figref idref="f0011">FIG <b>11</b>D</figref> depicts the end of vent conduit <b>1220</b> being located in the wound port <b>1210</b> above an exudate orifice <b>1230</b>.

0047Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims. For example, the individual fluid and vent conduits may be substituted for by a conduit having a dual lumen. To ensure the capillary action, one lumen must be larger than the other; however, the lumens may be coaxial or parallel.