Patent Description:
From <CIT> a wound covering assembly is known which includes a wound covering membrane and a removable layer. The wound covering membrane can allow liquid or air to pass through the wound covering membrane from a wound site covered by the wound covering membrane to ambient and vice versa. The removable layer covers a portion of the wound covering membrane and is removable from the wound covering membrane when the wound covering membrane is affixed to skin around the wound site. The removable layer is configured and connected with the wound covering membrane such that air and liquid are inhibited from passing through the wound covering membrane and the removable layer when the wound covering membrane is affixed to skin surrounding the wound site and the removable layer is connected with the wound covering membrane. The wound covering assembly can be used with a pump assembly to provide negative pressure to the wound site.

From <CIT> controlled pressure device for a tissue treatment is known which includes a reactor housing element, a reactor, and a cosmetic liquid or cream. The reactor housing element is configured to at least partially define an at least substantially air-tight enclosed volume around a tissue site when fixed in space in relation to the tissue site. The reactor is positioned in the enclosed volume and is configured to react with a selected gas found in air. The reactor consumes the selected gas within the enclosed volume. The cosmetic liquid or cream is also located in the enclosed volume.

Negative pressure therapy is a therapeutic treatment that utilizes negative pressure for skin treatments and restorative purposes. Negative pressure is a term used to describe a pressure that is below normal atmospheric pressure. Negative pressure therapy is utilized for several sites on the skin, such as a wound or an incision. Furthermore, negative pressure therapy is useful to manage wounds with complex healing concerns. Additionally, negative pressure therapy could also be used for cosmetic purposes like removing wrinkles.

Generally, negative pressure therapy is achieved by maintaining a reduced pressure beneath a dressing on a dressing site. A vacuum generation source, such as a pump, applies reduced pressure to the inside of the dressing on the dressing site. However, when a vacuum source that operates using a chemical reaction is first activated, a desirable negative pressure may not be obtained for the first few minutes of the operation of the vacuum source. As a result, if the dressing is not properly sealed at the beginning of the negative pressure therapy, an indication that the dressing is not sealed may not be noticeable for a few minutes. Furthermore, when a reduced pressure is finally obtained, the negative pressure may be susceptible to decreasing below a target pressure range for the negative pressure therapy (e.g., too much vacuum is applied on the skin). When the negative pressure decreases below the target pressure range, the dressing may be uncomfortable for the patient.

In view of the foregoing, the present invention relates to a negative pressure assembly with all features of claim <NUM>. A negative pressure assembly of the present invention includes a drape, a sealing element, a reactor, and a mechanical pump assembly. The drape covers a dressing site on a patient and when sealed against the skin upon application of a vacuum is capable of maintaining a negative pressure underneath the drape. When applied to the skin, the sealing element cooperates with the drape to define an enclosed volume covered by the drape and surrounded by the sealing element. The reactor is configured to react with and consume a selected gas found in air, and is located with respect to the drape and the sealing element to be in fluid communication with the enclosed volume when the drape is covering the dressing site. The mechanical pump assembly is fluidly connectable to the enclosed volume and has a pump chamber in fluid communication with the enclosed volume to draw air from the enclosed volume into the pump chamber.

The negative pressure assembly described above may further include a dressing including the drape and an absorbent material. Additionally, the reactor may be disposed in the dressing. Furthermore, a relief valve may be disposed on the dressing. The relief valve is in fluid communication with the enclosed volume and ambient. When a pressure differential between ambient and the enclosed volume is outside a predetermined pressure range, the relief valve allows gas from ambient to enter the enclosed volume.

The mechanical pump assembly can be connected to the dressing, and the pump chamber of the mechanical pump assembly is in fluid communication with the enclosed volume. The mechanical pump assembly can be connected to the dressing via a valve, a fitting, or a hose. The valve may be configured to allow gas to exit through the valve and into the pump chamber of the mechanical pump assembly while also preventing ambient air from entering into the enclosed volume through the valve. Alternatively, the valve may be a bidirectional valve configured to allow gas to exit through the valve when ambient pressure is below that of the enclosed volume and to allow gas from ambient to enter the enclosed volume through the valve when the pressure differential between ambient and the enclosed volume is outside a predetermined pressure range. Furthermore, the mechanical pump assembly may include a manually-actuated actuator and a biasing mechanism operatively connected with a movable pump element. When the manually-actuated actuator is actuated, the biasing mechanism moves the movable pump element. In result, air is drawn into the mechanical pump assembly. The biasing mechanism can be a spring, and the movable pump element can be a piston.

The negative pressure assembly described above may further include a chemical pump assembly including a chemical pump housing having a chamber. In this embodiment, the reactor is positioned in the chamber of the chemical pump housing instead of the dressing. Furthermore, the chemical pump assembly may include a diaphragm which moves toward the chamber to indicate when the chamber is under negative pressure. Additionally, the relief valve may alternatively be disposed on the chemical pump assembly instead of the dressing or may remain on the dressing.

The chemical pump housing may be connected to the dressing via a valve, a fitting, or a hose. Furthermore, the chemical pump assembly may be connected to a second dressing covering a second dressing site via a second valve, a second fitting, or the hose. The hose may be Y-shaped to connect the chemical pump assembly to the dressing and the second dressing at the same time. When the chemical pump housing is connected to the dressing, the chamber of the chemical pump assembly is in fluid communication with the enclosed volume. The hose may be retractable into the chemical pump assembly. Alternatively, the hose can be wound around a wrap element disposed on the chemical pump assembly. Also, when the chemical pump assembly is connected with the dressing via a fitting, the mechanical pump assembly may also be connected with the dressing via the fitting when the chemical pump assembly is not connected to the dressing via the fitting. Alternatively, the chemical pump assembly and the mechanical pump assembly may be connected to the dressing via separate valves, fittings, and/or hoses.

The negative pressure assembly may further include a dressing including the drape, the sealing element, and an absorbent material. The mechanical pump assembly is connectable to the dressing through the valve so that the pump chamber is in fluid communication with the enclosed volume. The negative pressure assembly may also include a reactor located with respect to the drape and the sealing element so that the reactor is in fluid communication with the enclosed volume when the drape is covering the dressing site. The reactor reacts with a selected gas found in air and consumes the selected gas. In one embodiment, the reactor is disposed in the dressing. In another embodiment, the negative pressure assembly further includes a chemical pump assembly having a chemical pump. housing in which the reactor is disposed in the chemical pump housing.

Furthermore, a relief valve may be disposed on the dressing. The relief valve is in fluid communication with the enclosed volume and ambient. The relief valve allows gas from ambient to enter the enclosed volume through the relief valve when a pressure differential between ambient and the enclosed volume is outside a predetermined pressure range. Alternatively, the valve may be a bidirectional valve that allows gas to exit through the valve when ambient pressure is below that of the enclosed volume and allows gas from ambient to enter the enclosed volume through the valve when the pressure differential between ambient and the enclosed volume is outside a predetermined pressure range. The predetermined pressure range may be between <NUM> and <NUM> mmHg below atmospheric pressure.

Additionally, the mechanical pump assembly may include a manually-actuated actuator and a biasing mechanism operatively connected with a movable pump element. The actuation of the manually-actuated actuator results in the biasing mechanism moving the movable pump element. In result, air is drawn into the mechanical pump assembly. The biasing mechanism may be a spring, and the movable pump element may be a piston. A hose may also be retractable into the mechanical pump assembly. Alternatively, the hose may be wound around a wrap element on the mechanical pump assembly. The mechanical pump assembly may further be connected to a second dressing covering a second dressing site via a valve, a fitting, or a hose.

<FIG> depicts a negative pressure kit <NUM> useful for negative pressure therapy. Negative pressure described herein is pressure below atmospheric pressure. The negative pressure kit <NUM> includes a tray kit <NUM> and a negative pressure assembly. In the embodiment depicted in <FIG>, the negative pressure assembly includes at least one dressing <NUM>, a chemical pump assembly <NUM>, and a mechanical pump assembly <NUM>.

The tray kit <NUM> comprises a top cover <NUM> and a bottom cover <NUM>. At least one recess <NUM> may be provided on the bottom cover <NUM> for storing the at least one dressing <NUM>, the chemical pump assembly <NUM>, and the mechanical pump assembly <NUM>. Spacer walls <NUM> can be added to maintain space between the top cover <NUM> and bottom cover <NUM> when the tray kit <NUM> is closed. The spacer walls <NUM> can at least partially surround the perimeter of the at least one recess <NUM>. The bottom cover <NUM> may further include securing elements for securing the components in the at least one recess <NUM>. Also, the tray kit <NUM> may comprise a closing element for keeping the top cover <NUM> and bottom cover <NUM> closed, and may further include locking attachments for locking the tray kit <NUM> when the tray kit <NUM> is closed.

With reference to <FIG>, the dressing <NUM> is placed over a dressing site <NUM> on a patient's skins. The dressing site <NUM> can be, but is not limited to, a wound, an incision, or skin where there is no wound or incision. In the illustrated embodiment, the dressing <NUM> includes a drape <NUM>, a wicking or absorbent element <NUM> and a fitting <NUM>. The dressing <NUM> can include further components, such as a sealing element <NUM>, and can be similar construction to the dressings described in <CIT> and/or <CIT>. The drape <NUM> can be made from a flexible material and can be made from a thin, flexible elastomeric film. Examples of such materials include polyurethane or polyethylene films. The drape <NUM> can include at least one opening <NUM> (see <FIG>), which can cooperate with the fitting <NUM>. The drape <NUM> in the illustrated embodiment is a thin film capable of maintaining a negative pressure underneath the drape <NUM> when sealed against the skin upon application of a vacuum when the opening <NUM> is not in communication with ambient.

The drape <NUM> further comprises a drape top <NUM> and a drape edge <NUM>. The drape top <NUM> and the drape edge <NUM> can be made from one continuous piece or multiple pieces fused together. The drape edge <NUM> is placed around the dressing site <NUM>, and the drape top <NUM> covers the dressing site <NUM>. The drape <NUM> can be made in a variety of shapes and sizes to cover a variety of dressing sites <NUM>. The opening <NUM> extends through the drape top <NUM>.

With continued reference to <FIG>, the sealing element <NUM> cooperates with the drape <NUM> and the skin S to create an enclosed volume <NUM> defined between the drape <NUM> and the dressing site <NUM> and surrounded by the sealing element <NUM>. The sealing element <NUM> can be separate from the dressing <NUM> or a component of the dressing <NUM>. The sealing element <NUM> functions like a gasket, as the sealing element <NUM> prevents fluid (including air) from escaping between the drape <NUM> and the skin S. When properly sealed, air or select gases found in air can selectively exit the dressing <NUM> through the at least one opening <NUM> and fitting <NUM>. Thus, the sealing element <NUM> helps maintain negative pressure within the dressing <NUM>. The sealing element <NUM> can be made from a material such as silicone or a hydrogel material.

The dressing <NUM> may further include a wound contact layer <NUM>. The drape top <NUM> covers the wound contact layer <NUM> and/or the wicking or absorbent element <NUM>. The wound contact layer <NUM> can be made of an elastomeric material, such as a polymeric material that has rubber-like properties. Furthermore, the wound contact layer <NUM> can be an elastomeric material that is a thin, flexible elastomeric film. Some examples of such materials include a silver coated nylon, a perforated silicone mesh, or other materials that will not stick to the patient's tissue. The wound contact layer <NUM> contacts the dressing site <NUM>. The wound contact layer <NUM> can include at least one opening to cooperate with the wicking element <NUM> to retain exudate traveling from the dressing site <NUM> into the enclosed volume <NUM>. The sealing element <NUM> can also be disposed on the side of the wound contact layer <NUM> that contacts the dressing site <NUM> (or the wicking element <NUM> if the wound contact layer <NUM> is not included).

A drape release liner (not shown) is disposed on the bottom surface of the drape edge <NUM>. The drape release liner is removed before the dressing <NUM> is applied to the dressing site <NUM>. When the drape release liner is removed, an adhesive <NUM> on the bottom surface of the drape edge <NUM> is exposed. As the dressing <NUM> is placed on the patient, the adhesive <NUM>, which can be an acrylic-based adhesive that is distinct from the sealing element <NUM>, secures the drape edge <NUM> to the patient's skin S around the dressing site <NUM>. Thus, contact is maintained between the drape edge <NUM> and the skin S.

The wicking or absorbing element <NUM> is made from an absorbent material that is capable of absorbing exudate from the dressing site <NUM>. The wicking element <NUM> can be made from super absorbent polymers, absorbent beads, foams, or natural absorbents. Also, the wicking element <NUM> can provide appropriate voids for gases found in air so that reduced pressure can be maintained. For example, the wicking element <NUM> can be made from a relatively more rigid foam as compared to the drape <NUM> so that gas voids are maintained while absorbing exudate from the wound. The wicking element <NUM> could also be made from the superabsorbent polymers described above that expand and form gas voids, for example between adjacent beads, to provide aforementioned volume control. The wicking element <NUM> can also be a hydroactive wound pad available under the trademark Vilmed®, which chemically absorbs exudate and precludes the exudate from passing through the wicking element toward the vacuum source unlike a sponge.

The dressing <NUM> can also include an air permeable liquid impervious membrane <NUM> covering the opening <NUM> in the drape top <NUM>. In an embodiment, the air permeable liquid impervious membrane <NUM> is disposed on the bottom surface of the drape top <NUM>. Air is allowed to travel through the air permeable liquid impervious membrane <NUM>, whereas liquid is prevented from traveling through the air permeable liquid impervious membrane <NUM>. Therefore, exudate is not able to flow through the air permeable liquid impervious membrane <NUM>. In another embodiment, the air permeable liquid impervious membrane <NUM> is disposed on the top surface of the drape top <NUM>. Furthermore, <FIG> depicts a chemical pump <NUM> in the form of a reactor disposed in the dressing <NUM> beneath the drape <NUM>. The chemical pump <NUM> can be located elsewhere, which will be described in more detail below.

<FIG> depicts the dressing <NUM> connected with the mechanical pump assembly <NUM> via a hose <NUM> (schematically depicted). When the mechanical pump assembly <NUM> is connected to the dressing <NUM>, the mechanical pump assembly <NUM> is in fluid communication with the enclosed volume <NUM> via the fitting <NUM> in a manner described in more detail below. Actuation of the mechanical pump assembly <NUM> draws air from the enclosed volume <NUM> through the opening <NUM>, fitting <NUM>, and hose <NUM> into the mechanical pump assembly <NUM>. As such, the sealing of the dressing <NUM> against the skin S can be checked in that the drape <NUM> would be drawn toward the skin S. The hose <NUM> can then be removed from the fitting <NUM>, which would allow air into the enclosed volume <NUM> resulting in the enclosed volume <NUM> returning towards atmospheric pressure.

<FIG> depicts the dressing <NUM> and the chemical pump assembly <NUM>. The chemical pump assembly <NUM> includes a chemical pump housing <NUM>, a chemical pump <NUM> (shown in phantom in <FIG>) positioned in a chamber <NUM> (see <FIG>), and a lower opening <NUM> disposed on the bottom of the chemical pump housing <NUM> and in fluid communication with the chamber <NUM>. When connected with the fitting <NUM>, the chamber <NUM> in the chemical pump housing <NUM> is in fluid communication with the enclosed volume <NUM> via the lower opening <NUM>, the at least one opening <NUM>, and the fitting <NUM> on the drape <NUM>. The chemical pump assembly <NUM> applies reduced pressure on the inside of the dressing <NUM> in a manner that will be described in more detail below.

The chemical pump <NUM> in the chemical pump assembly <NUM> is a reactor configured to react with a selected gas found in air. The chemical pump <NUM> is located with respect to the drape <NUM> and sealing element <NUM> so that the chemical pump <NUM> can be in fluid communication with the enclosed volume <NUM>. The chemical pump <NUM> consumes the selected gas from the enclosed volume <NUM>, thereby removing the gas and reducing the gas pressure. Examples of reactors that can be used in the chemical pump assembly <NUM> are described in <CIT> and <CIT>. In the case of a therapeutic negative pressure system, utilized for wound care, the range of reported operating pressures, relative to standard atmospheric pressure of <NUM> mmHg, are -<NUM> mmHg to -<NUM> mmHg (absolute pressure of <NUM> to <NUM> mmHg). When the pressure is less than <NUM> mmHg, the at least one dressing <NUM> can become uncomfortable for the patient. When the pressure is above <NUM> mmHg, the negative pressure therapy may not be as effective compared to pressures below <NUM> mmHg. However, smaller target pressure ranges within the <NUM> to <NUM> mmHg may be desired. Thus, the reactor <NUM> can be configured to maintain a reduced pressure range within a predetermined target pressure range.

The chemical pump assembly <NUM> is configured to maintain a predefined chamber volume, as the chemical pump <NUM> consumes the selected gas from the enclosed volume <NUM>. The size of the reactor <NUM> is dependent on the volume of the chamber <NUM>, the hose <NUM> and the enclosed volume <NUM>, among other factors. In another embodiment, the reactor <NUM> can be disposed in the dressing <NUM> instead of the chemical pump assembly <NUM>, as depicted in <FIG>. As a result, the chemical pump assembly <NUM> may be eliminated in the method of applying negative pressure within the dressing <NUM>.

In the illustrated embodiment of <FIG>, an upper opening <NUM>, in which a first valve <NUM> is disposed, is provided on the top of the chemical pump housing <NUM>. Additionally, the upper opening <NUM> and first valve <NUM> can be disposed on a side of the chemical pump housing <NUM> and elsewhere on the chemical pump housing <NUM>. In another embodiment, a valve that operates similarly to the first valve <NUM> can be disposed on the dressing <NUM>. The first valve <NUM> is configured to work with the mechanical pump assembly <NUM>. In the first operating state, the first valve <NUM> allows air to exit the chamber <NUM> through the first valve <NUM> when the mechanical pump assembly <NUM> is inserted into the first valve <NUM>. In the second operating state, the first valve <NUM> precludes ambient air from entering the chamber <NUM> through the upper opening <NUM> and first valve <NUM> when the mechanical pump assembly <NUM> is not inserted into the first valve <NUM>. Examples of such valves include, but are not limited to, a spring-biased check valve and a valve comprising flaps. <FIG> depicts the first valve <NUM> having flaps <NUM>. The flaps <NUM> on the first valve <NUM> are closed before the mechanical pump assembly <NUM> is introduced into the upper opening <NUM>. No gas is allowed to escape through the upper opening <NUM> and the first valve <NUM> unless the mechanical pump assembly <NUM> is introduced. The flaps <NUM> on the first valve <NUM> return to the closed position by their resilient forces, as the mechanical pump assembly <NUM> is removed.

In the illustrated embodiment, a sealing member <NUM> is disposed on the bottom of the chemical pump housing <NUM>. Also, the sealing member <NUM> can be disposed on a side of the chemical pump housing <NUM> and elsewhere on the chemical pump housing <NUM>. In the illustrated embodiment, the sealing member <NUM> is positioned in the lower opening <NUM> and configured to work with the fitting <NUM>. The sealing member <NUM> allows air to enter the chamber <NUM> through the lower opening <NUM> when the chemical pump assembly <NUM> is pressed onto and fitted with the fitting <NUM>. The sealing member <NUM> prevents ambient air from entering the chamber <NUM> when the chemical pump assembly <NUM> is not fitted onto the fitting <NUM>. <FIG> depicts the sealing member <NUM> having flaps <NUM>. The flaps <NUM> on the sealing member <NUM> are closed before the chemical pump assembly <NUM> is fit onto the fitting <NUM>. No gas is allowed to enter through the sealing member <NUM> unless the flaps <NUM> are moved from their initial closed position. Alternatively, the sealing member <NUM> can be foil or another member capable of being punctured when pressed against the fitting <NUM>.

With reference to <FIG>, a negative pressure indicator, which in the illustrated embodiment is a diaphragm <NUM>, may be disposed on the chemical pump housing <NUM> to provide an indication to the user that the system is under negative pressure. Referring to <FIG>, the diaphragm <NUM> can be dome shaped protruding out of the chemical pump housing <NUM> when the pressure in the chamber <NUM> is at or above a predetermined pressure, which can be atmospheric pressure. The diaphragm <NUM> can be made from an elastic material. As the pressure in the chemical pump assembly <NUM> or dressing <NUM> decreases below the target pressure range, the diaphragm <NUM> is drawn into the chemical pump housing <NUM>. As the diaphragm <NUM> is drawn towards the inside of the chemical pump housing <NUM>, the diaphragm <NUM> is inverted. When the diaphragm <NUM> is inverted, this provides an indication to the user that the system is under negative pressure. Alternatively, the indicator can be disposed on the dressing <NUM>.

<FIG> and <FIG> schematically depict the mechanical pump assembly <NUM>. In the illustrated embodiment, the mechanical pump assembly <NUM> is a single action vacuum source used to create negative pressure in the enclosed volume <NUM> of the dressing <NUM>. When the chemical pump assembly <NUM> is initially installed on the dressing <NUM> (see <FIG>), negative pressure in the enclosed volume <NUM> of the dressing <NUM> is not created until the chemical pump assembly <NUM> is in full operation, i.e., until the reactor <NUM> scavenges the selected gas found in air from the chamber <NUM> and the enclosed volume <NUM>. Therefore, the mechanical pump assembly <NUM> can also assist in the negative pressure maintenance of the dressing <NUM>. Furthermore, the mechanical pump assembly <NUM> can assist in drawing the dressing <NUM> towards the dressing site <NUM>.

In one embodiment, the mechanical pump assembly <NUM> may include a manually-actuated actuator and a biasing mechanism operatively connected with a movable pump element. The actuation of the manually-actuated actuator results in the biasing mechanism moving the movable pump element so as to draw air into the mechanical pump assembly. In result, negative pressure is created in the enclosed volume <NUM>. Thus, the mechanical pump assembly <NUM> can be a pneumatic piston cylinder. With reference to <FIG>, the mechanical pump assembly <NUM> comprises a mechanical pump housing <NUM>, and a pump chamber having a first chamber <NUM> and a second chamber <NUM>. An actuator <NUM> may be disposed on the side of the mechanical pump housing <NUM>. The actuator <NUM> can be manually operated and used to activate the operation of the mechanical pump assembly <NUM>. Examples of such actuators include, but are not limited to, a button, a switch, or a trigger.

An internal wall <NUM> may be used to separate the first chamber <NUM> from the second chamber <NUM>. The internal wall <NUM> includes a rod opening <NUM> for accepting a piston rod <NUM>. A seal <NUM> encircles the internal wall <NUM> to prevent any gas from passing between the first chamber <NUM> and the second chamber <NUM> around the internal wall <NUM>. Alternatively, the internal wall <NUM> can be integrally formed with the mechanical pump housing <NUM>. Furthermore, a second seal <NUM> in the rod opening <NUM> can enclose the piston rod <NUM> so that gas is prevented from passing between the first chamber <NUM> and the second chamber <NUM> through the rod opening <NUM> without restricting the movement of the piston rod <NUM>.

The mechanical pump housing <NUM> includes a tip <NUM> disposed at the bottom. The tip <NUM> includes a tip opening <NUM> in fluid communication with the first chamber <NUM>. Furthermore, the mechanical pump assembly <NUM> can also be in fluid communication with the opening <NUM> on the drape <NUM> via the hose <NUM> that can connect with the tip <NUM> or via the tip connecting directly with the fitting <NUM>. The hose <NUM> can be any length, thus a long hose <NUM> can be utilized. Therefore, the mechanical pump assembly <NUM> can be operated on the dressing <NUM> before the chemical pump assembly <NUM> is installed on the dressing <NUM>. This can help seal the dressing <NUM> at the dressing site <NUM>. In result, the mechanical pump assembly <NUM> can directly apply reduced pressure to the dressing <NUM>.

In the illustrated embodiment, the biasing mechanism is a spring <NUM>, and the movable element is a piston <NUM>. The spring <NUM> and the piston <NUM> are disposed in the first chamber <NUM>. Before the mechanical pump assembly <NUM> is activated, a majority of the piston rod <NUM> is also located in the first chamber <NUM>. Also, a head <NUM> disposed on the top of the piston rod <NUM> is disposed in the second chamber <NUM>. When the mechanical pump assembly <NUM> is introduced to the first valve <NUM> (<FIG>) of the chemical pump assembly <NUM> or connected with the fitting <NUM> by the hose <NUM> (<FIG>), the actuator <NUM> is used to activate the operation of the mechanical pump assembly <NUM>. As the mechanical pump assembly <NUM> is activated, a connector <NUM> (see <FIG>) between the actuator <NUM> and the piston rod <NUM> releases the piston rod <NUM>, and air enters first chamber <NUM> of the mechanical pump housing <NUM> through the tip opening <NUM>. The connector <NUM> can reengage the piston rod <NUM>. Thus, the mechanical pump assembly <NUM> may be reusable. As depicted in <FIG>, the spring <NUM> biases the piston <NUM> toward the internal wall <NUM>, which draws air into the first chamber <NUM>. The piston rod <NUM> moves into the second chamber <NUM>, and the head <NUM> moves towards the top surface of the mechanical pump housing <NUM>. As a result, the negative pressure of the dressing <NUM> is created.

The negative pressure assembly can be susceptible to reaching a negative pressure below the target pressure range, e.g. too much vacuum or negative pressure may be achieved in the enclosed volume <NUM>. In order to maintain the target pressure range, as shown in <FIG>, a relief valve <NUM> may be disposed on the chemical pump housing <NUM> to release pressure as needed. Alternatively, a relief valve similar in operation to the relief valve <NUM> can be disposed on the drape <NUM> of the dressing <NUM>. The relief valve <NUM> can be any valve that can manually or automatically release pressure as needed. <FIG> depicts one embodiment in which the relief valve <NUM> is disposed on the chemical pump assembly <NUM>. It is to be understood that the relief valve <NUM> functions similarly in an embodiment in which the relief valve <NUM> is disposed on the dressing <NUM>. Referring to <FIG>, the relief valve <NUM> comprises a flexible cap <NUM> protruding into the chemical pump housing <NUM> connected with a post <NUM>. The flexible cap <NUM> normally covers an opening <NUM>. The flexible cap <NUM> can be made from an elastic material. As a pressure differential between ambient and the dressing <NUM> or ambient and the chamber <NUM> in the chemical pump assembly <NUM> moves outside of a predetermined pressure range, which can be set for example between <NUM> mmHg and <NUM> mmHg, the flexible perimeter <NUM> of the flexible cap <NUM> is drawn into the chemical pump housing <NUM> or the drape <NUM>. As the flexible perimeter <NUM> of the flexible cap <NUM> is drawn toward the inside of the chemical pump housing <NUM> or the dressing <NUM>, a space is created around the perimeter of the flexible cap <NUM> so that air can pass through the opening <NUM>. When the opening <NUM> is not covered by the flexible cap <NUM>, air from the ambient enters the chemical pump assemble <NUM> or the dressing <NUM> until the internal pressure reaches the pressure at which the perimeter <NUM> of the flexible cap <NUM> relaxes onto the inner surface of the chemical pump housing <NUM> to reseal and close the opening <NUM>. The chemical pump assembly <NUM> and/or the dressing <NUM> are then subject to the amount of negative pressure at which the relief valve <NUM> reseals, which can be different than the pressure differential at which the opening <NUM> is opened while still being within the therapeutic range, e.g., between <NUM> mmHg and <NUM> mmHg.

In another embodiment, a bidirectional valve <NUM> is disposed on the chemical pump housing <NUM> instead of the first valve <NUM> and the release valve <NUM>, as depicted in <FIG>. Alternatively, the bidirectional valve <NUM> can be disposed on the at least one dressing <NUM>. In yet another embodiment, the bidirectional valve <NUM> may be similar construction to the valve described in <CIT>. The chemical pump assembly <NUM> may be in fluid communication with the enclosed volume <NUM> through the bidirectional valve <NUM>. Additionally, the mechanical pump assembly <NUM> may also be in fluid communication with the enclosed volume <NUM> through the bidirectional valve <NUM>. As depicted in <FIG>, the hose <NUM> can be attached to the mechanical pump assembly <NUM> and inserted into the bidirectional valve <NUM>. In result, the mechanical pump assembly <NUM> is in fluid communication with the enclosed volume <NUM>.

The bidirectional valve <NUM> may include three operating states. In the first operating state, gas is allowed to exit the chamber <NUM> and/or the enclosed volume <NUM> through the bidirectional valve <NUM> when the external pressure is below that of the enclosed volume <NUM> and/or the chamber <NUM>. In the second operating state, the bidirectional valve <NUM> precludes gas from entering or exiting the enclosed volume <NUM> and/or the chamber <NUM> through the bidirectional valve <NUM> when the pressure of the chamber <NUM> and/or the enclosed volume <NUM> is between the first predetermined threshold and a second predetermined threshold. In the third operating state, the bidirectional valve <NUM> allows gas from ambient to enter the enclosed volume <NUM> and/or the chamber <NUM> through the bidirectional valve <NUM> when the pressure in the enclosed volume <NUM> and/or the chamber <NUM> is below the predetermined threshold. In one embodiment, the predetermined threshold is <NUM> mmHg or 200mmHg below atmospheric. In yet another embodiment, the bidirectional valve <NUM> may include springs that automatically actuate the bidirectional valve <NUM> when a pressure differential is at the first or second predetermined threshold.

In still another embodiment, the mechanical pump assembly <NUM> is connected to multiple dressings. Furthermore, the mechanical pump assembly <NUM> can be connected to the multiple dressings at the same time. For example, the mechanical pump assembly <NUM> can be connected to a second dressing <NUM>. The hose <NUM> can include a Y-shaped fitting <NUM> to connect the mechanical pump assembly <NUM> to the dressing <NUM> and the second dressing <NUM> at the same time. Furthermore, the chemical pump assembly <NUM> can also be connected to multiple dressings and can be connected to the multiple dressings at the same time. As depicted in <FIG>, the hose <NUM> can include the Y-shaped fitting <NUM> to simultaneously connect the chemical pump assembly <NUM> to the dressing <NUM> and the second dressing <NUM>.

A method for achieving negative pressure therapy with the negative pressure kit <NUM> will be described hereinafter. First, at least one dressing <NUM> is removed from the tray kit <NUM>, and the drape release liner is removed to expose the adhesive <NUM> on the bottom surface of the drape edge <NUM>. The drape edge <NUM> is placed on skin S around at least one dressing site <NUM> and is secured to the skin S by the adhesive <NUM>.

With reference to <FIG>, the drape <NUM> is secured over the dressing site <NUM>, and the second valve <NUM> on the chemical pump assembly <NUM> is introduced to the fitting <NUM> on the drape <NUM>. The second valve <NUM> is placed over the fitting <NUM>, and the flaps <NUM> are opened. When the flaps <NUM> are open, the chemical pump assembly <NUM> is in fluid communication with the dressing <NUM>. The reactor <NUM> begins to consume the selected gas from the enclosed volume <NUM> but is not complete at this time.

Afterwards, the mechanical pump assembly <NUM> is inserted into the first valve <NUM> disposed on the chemical pump assembly <NUM> to open the flaps <NUM>, as depicted in <FIG>. As the flaps <NUM> are opened, the mechanical pump assembly <NUM> is in fluid communication with the chamber <NUM> in the chemical pump assembly <NUM>. Alternatively, the mechanical pump assembly <NUM> is inserted into the bidirectional valve <NUM>. Also, the mechanical pump assembly <NUM> is in fluid communication with the enclosed volume <NUM> via the chemical pump assembly <NUM>. When the mechanical pump assembly <NUM> is in fluid communication with the chemical pump assembly <NUM>, the actuator <NUM> is used to activate the operation of the mechanical pump assembly <NUM>, as depicted in <FIG>. Then, the spring <NUM> pushes the piston <NUM> towards the internal wall <NUM>. As the piston <NUM> moves, air enters the first chamber <NUM> of the mechanical pump assembly <NUM>, and the dressing <NUM> is drawn toward the skin S. The mechanical pump assembly <NUM> is then removed, and the flaps <NUM> of the first valve <NUM> are closed by their resilient forces, as depicted in <FIG>. In the embodiment with the bidirectional valve <NUM>, the bidirectional valve <NUM> moves to the second operating state, as the mechanical pump assembly <NUM> is removed from the bidirectional valve <NUM>. The reactor <NUM> in the chemical pump assembly <NUM> can continue to apply or maintain reduced pressure to the dressing <NUM>. In result, the pressure in the dressing <NUM> is reduced to a negative pressure, and the negative pressure indicator <NUM> signals when the negative pressure has been achieved. At any time the reduced pressure decreases below a target pressure range, the relief valve <NUM> or the bidirectional valve <NUM> releases pressure as needed to restore the reduced pressure to a predetermined pressure differential. In another embodiment, the mechanical pump assembly <NUM> can be inserted prior to the chemical pump assembly <NUM>. First, the at least one dressing <NUM> is placed and secured over the at least one dressing site <NUM>. Then, the mechanical pump assembly <NUM> is connected to the fitting <NUM> on the dressing <NUM> by the hose <NUM>. Alternatively, the first valve <NUM> or bidirectional valve <NUM> is disposed on the dressing <NUM> instead of the chemical pump assembly <NUM> to provide direct fluid communication between the dressing <NUM> and the mechanical pump assembly <NUM>. As a result, the mechanical pump assembly <NUM> is in fluid communication with the enclosed volume <NUM>. The first valve <NUM> or bidirectional valve <NUM> may further replace the fitting <NUM>. In these alternate embodiments, the mechanical pump assembly <NUM> is inserted into the first valve <NUM> or the bidirectional valve <NUM> on the dressing <NUM>.

After the mechanical pump assembly <NUM> is connected to the dressing <NUM>, the mechanical pump assembly <NUM> is activated with the actuator. In result, the piston <NUM> moves toward the internal wall <NUM>, and air enters the first chamber <NUM> of the mechanical pump assembly <NUM>. The mechanical pump assembly <NUM> is removed and replaced by the chemical pump assembly <NUM>. The reactor <NUM> in the chemical pump assembly <NUM> begins reacting with a selected gas found in air to maintain the negative pressure of the dressing. When the negative pressure in the enclosed volume <NUM> is achieved, the indicator on the dressing <NUM> and/or the chemical pump assembly <NUM> signals when the dressing <NUM> reaches a negative pressure. As needed, the relief valve <NUM> or the bidirectional valve <NUM> releases pressure when the reduced pressure decreases below a target pressure range.

In still another embodiment, the chemical pump assembly <NUM> and the mechanical pump assembly <NUM> are both connected to the at least one dressing <NUM>. In this embodiment, a first valve, fitting, or hose and a second valve, fitting or hose are disposed on the dressing <NUM>. The chemical pump assembly <NUM> is connected to the dressing via the first valve, fitting, or hose. The mechanical pump assembly <NUM> is connected for the second valve, fitting, or hose. For example, the chemical pump assembly <NUM> is connected to the dressing <NUM> via the fitting <NUM> disposed on the dressing <NUM>, while the mechanical pump assembly <NUM> is connected to the dressing <NUM> via the hose <NUM> and a second fitting <NUM> disposed on the dressing <NUM>, as depicted in <FIG>. Also, in particular when the dressing <NUM> that includes at least one relief valve similar to the relief valve <NUM> described above, the chemical pump assembly <NUM> could be replaced with an electro-mechanical pump similar to those now used with known negative pressure wound therapy devices. Different than known negative pressure wound therapy devices, however, the relief valve(s) on the dressing <NUM> can open and close (as described above) to maintain the enclosed volume underneath the dressing within the therapeutic range. Also, in lieu of the relief valves, the dressing <NUM> could include a bidirectional valve similar to the bidirectional valve <NUM> that could cooperate with the mechanical pump assembly <NUM> while an electro-mechanical pump similar to those now used with known negative pressure wound therapy devices could connect with the fitting <NUM> shown in <FIG>.

Furthermore, at least one attachment can be disposed on the mechanical pump assembly <NUM> or the chemical pump assembly <NUM> for storing the hose <NUM>. An example of such an attachment is, but is not limited to, a wrap element. With reference to <FIG>, the chemical pump assembly <NUM> may include a wrap element <NUM> disposed on the chemical pump housing <NUM> around which the hose <NUM> can be wound. Alternatively, the wrap element <NUM> can be disposed on the mechanical pump housing <NUM>. The hose <NUM> can be coiled around the at least one attachment so that the hose <NUM> is secured during storage and transportation. In another embodiment, the hose <NUM> can retract into the chemical pump assembly <NUM>. In yet another embodiment, the hose <NUM> can retract into the mechanical pump assembly <NUM>. Alternatively, the tray kit <NUM> can include an additional recess for storing the hose <NUM>.

Claim 1:
A negative pressure assembly (<NUM>) comprising:
a drape (<NUM>) for covering a dressing site (<NUM>) on a patient and capable of maintaining a negative pressure underneath the drape (<NUM>) when sealed against skin (S) upon application of a vacuum;
a sealing element (<NUM>) that when applied to the skin (S) cooperates with the drape (<NUM>) to define an enclosed volume (<NUM>) covered by the drape (<NUM>) and surrounded by the sealing element (<NUM>);
a reactor (<NUM>) located with respect to the drape (<NUM>) and the sealing element (<NUM>) so as to be in fluid communication with the enclosed volume (<NUM>) when the drape (<NUM>) is covering the dressing site (<NUM>), the reactor (<NUM>) being configured to react with a selected gas found in air so as to consume the selected gas; and
a mechanical pump assembly (<NUM>) including a pump chamber fluidly connectable to the enclosed volume (<NUM>), and configured to draw air from the enclosed volume (<NUM>) into the pump chamber when fluidly connected with the enclosed volume (<NUM>).