WO2011162862A1

WO2011162862A1 - Wound dressing

Info

Publication number: WO2011162862A1
Application number: PCT/US2011/032296
Authority: WO
Inventors: Tinh Nguyen-Demary; Mingliang Lawrence Tsai
Original assignee: Convatec Technologies Inc.
Priority date: 2010-06-23
Filing date: 2011-04-13
Publication date: 2011-12-29

Abstract

A wound dressing is provided with a built-in manually manipulatable device for generating topical negative pressure within the dressing. The dressing comprises: a wound interface region, a seal, and a resiliently recoverable device. The resiliently recoverable device is carried by or in the wound dressing, for generating a negative pressure within at least a portion of the wound dressing as the resiliently recoverable device recovers resiliently from a deformed state. The negative pressure is optionally applied to the wound interface region. The seal obstructs entry of air and thereby preserves the negative pressure. The resiliently recoverable device may be manipulated manually, e.g. by compressing manually, to reprime the dressing for generating negative pressure.

Description

WOUND DRESSING

Field of the Invention

The present invention relates to a wound dressing, in particular a dressing using topical negative pressure for managing wound exudate.

Background to the Invention

Wound exudate can be described as the liquid produced from chronic wounds, fistula or acute wounds once haemostasis has been achieved. For centuries, the production of exudate was regarded as an inevitable consequence of the formation of many types of wound. In more recent times it has been recognized that exudate contains a complex mixture of bioactive molecules that have both positive and negative effects on the healing process. Management of exudate at the wound site is an important part of modern wound care.

Because excessive exudate can cause maceration of peri-wound skin, which in turn can lead to infection, considerable attention has been given to the development of wound dressings that prevent the accumulation of large volumes of exudate fluid within a wound, and prevent the fluid from spreading over the surrounding healthy tissue. One known method of modern exudate management is by means of a topical negative pressure (TNP). TNP is the application of sub-atmospheric pressure (i.e. negative pressure with respect to atmosphere) to draw exudates away from the wound site.

A disadvantage of current TNP devices is that their nature of device design restricts their use to hospital, or for patients who are bedbound. Current devices utilize a special wound dressing that is coupled by a suction conduit to a separate suction source and exudate collection receptacle. The suction source is electrically powered, and typically includes an electric pump to generate negative pressure. The electrical power has to be supplied either from a main source or from a battery. The suction source and exudate collection receptacle are mounted on the patient's bed, or carried by a suitable equipment stand. The devices are, by their nature, relatively complex, bulky, heavy and expensive compared to traditional passive, non- TNP wound dressings. The wearer's mobility and ability to perform everyday activities are severely restricted.

It would be desirable to address one or more of the above disadvantages.

Summary of the Invention

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

Broadly speaking, one aspect of the invention provides a wound dressing comprising: a wound interface region, a seal, and a resiliently recoverable device. The wound interface region is permeable or open to wound exudate to allow exudate to enter the dressing. The seal creates a substantially airtight seal between the dressing and skin around the wound interface region. The resiliently recoverable device is carried by or in the wound dressing, for generating a negative pressure within at least a portion of the wound dressing as the resiliently recoverable device recovers resiliently from a deformed state. The negative pressure is optionally applied to the wound interface region. The seal obstructs entry of air and thereby preserves the negative pressure.

Broadly speaking, another aspect of the invention provides a wound dressing comprising a wound interface region, a seal, a cover layer, and a manually manipulatable device. The wound interface region is permeable or open to wound exudate to allow exudate to enter the dressing. The seal creates a substantially airtight seal between the dressing and skin around the wound interface region. The manually manipulatable device is disposed between the seal and the cover layer for generating in response to, or recovering from, manual manipulation, a negative pressure at the wound interface region. The seal obstructs entry of air and thereby preserves the negative pressure. Features, objects and advantages of the invention include any one or a combination of any two or more, of: a TNP wound dressing that generates TNP at the wound dressing without coupling to an external suction source; a TNP dressing that avoids a need for an electrical power supply; a TNP wound dressing that can be worn by a mobile patient and/or used in environments other than hospitals and bedside care; a TNP wound dressing that permits the wearer to perform his or her usual daily activities while wearing the dressing; a TNP wound dressing that is lightweight; a TNP wound dressing that is compact; a TNP wound dressing that is inexpensive to manufacture; a TNP wound dressing useable easily by members of the public; a TNP dressing with a manually manipulatable device forming part of the wound dressing that a wearer or caregiver can use to regenerate TNP should the negative pressure begin to subside.

Additional features, objects and advantages of the invention will become apparent from the following description and claims. Protection may be claimed for any novel idea described herein and/or illustrated in the drawings, whether or not emphasis has been placed thereon.

Brief Description of the Drawings

Fig. 1 is a schematic cross-section through a TNP wound dressing of a first embodiment of the invention;

Fig. 2 is a schematic cross-section through a TNP wound dressing of a second embodiment of the invention.

Fig. 3 is a schematic partial cross-section illustrating the process of priming the resiliently recoverable device.

Fig. 4 is a schematic partial cross-section illustrating the process of suction generation by the resiliently recoverable device.

Fig. 5 is a schematic top view illustrating a third embodiment of TNP wound dressing with a modified layout;

Fig. 6 is a schematic cross-section through a portion of the wound dressing of Fig. 5 (other side corresponds). Detailed Description of the Invention

Figs. 1 and 2 illustrate similar first and second embodiments of a wound dressing 10 using topical negative pressure (TNP) to manage wound exudate from a wound site 12. In contrast to the aforementioned prior TNP wound dressings, embodiments of the present invention create the negative pressure within the wound dressing itself, thereby avoiding many of the disadvantages associated with having to use a separate, external suction source. As explained in further detail, the embodiments illustrate use of a resiliently recoverable device to generate negative pressure. Additionally or alternatively, the embodiments illustrate use of a manually manipulatable device forming part of the wound dressing to generate negative pressure. In the illustrated embodiments the manually manipulatable device and the resiliently recoverable device are the same item 20.

The wound dressing 10 comprises a wound interface region 14 for contacting the wound site 12, and a seal 16 for creating a substantially airtight seal between the wound dressing 10 and periwound skin 18 circumscribing or surrounding the wound site 12. As explained in more detail, in use, the wound dressing 10 generates topical negative pressure, which is used to draw exudate into the dressing. The term "substantially airtight" for the seal 16 as used herein means sufficiently airtight to isolate the negative pressure at the wound interface region 14, from surrounding atmospheric pressure, to enable the negative pressure to be maintained efficiently. The term "substantially airtight" for the seal 16 as used herein means an air flow leakage rate no greater than 0.1 cc/min at about 0.36 psi (10" water head), or preferably no greater than 0.01 cc/min, or preferably no greater than 0.001 cc/min at about 0.36 psi. In the illustrated embodiments, the seal 16 is implemented by, or comprises, a skin compatible adhesive. The adhesive may be pressure-sensitive. A suitable adhesive may be selected from one or more of the following types: hydrocolloid adhesive; polyurethane adhesive; acrylic adhesive; silicone adhesive; hydrogels; gels. The seal 16 may be of closed-loop form extending around the wound interface region 14, or the seal 16 may comprise a layer that extends across the wound interface region 14, the layer being apertured or perforated to define the wound interface region 14 therein. The wound dressing 10 further comprises a resiliently recoverable device (also referred to as a manually manipulatable device) 20 for generating negative pressure within at least a portion of the wound dressing 10 as the resiliently recoverable device 20 recovers resiliently from a deformed shape or state. A first compartment 22 of the dressing varies in volume depending on the degree of deformation of the resiliently recoverable device 20. The resiliently recoverable device 20 is configured to urge the first compartment 22 to expand progressively in volume as the resiliently recoverable device 20 recovers its shape progressively from a deformed state. The urging pressure exerted by the resiliently recoverable device 20 depends at least partly on the spring constant of the resiliently recoverable device 20. The increase in volume of the first compartment 22 causes a decrease in the air pressure within the first compartment 22, thereby generating negative pressure compared to surrounding atmospheric pressure. Since there is little or no leakage through the seal 16 if proper application procedures are followed, equilibrium is established when the degree of negative pressure (e.g., the difference between the reduce pressure and surrounding atmospheric pressure) balances the urging pressure exerted by the resiliently recoverable member 20. Such an equilibrium pressure is maintained inside of wound dressing 10, including the first compartment 22 and/or the second compartment 34.

In use, the wound interface region 14 of the wound dressing 10 is exposed to the negative pressure generated within the first compartment 22, to apply TNP to the wound site. The TNP is believed to be advantageous in drawing wound excess exudate into the wound dressing, thereby avoiding problems of excess exudate macerating periwound skin. TNP is also believed to reduce infection rates and increase localized blood flow within the wound site 12. The magnitude of the negative pressure can be designed to be no greater than a desired maximum according to the particular design of the wound dressing. For example, the negative pressure may be designed to be less than about 150mm Hg, or preferably no greater than about 125mm Hg, or more preferably no greater than about 75mm Hg.

The use of a resiliently recoverable device enables the negative pressure to be generated within the wound dressing, instead of being supplied for a separate source external to the wound dressing. The resiliently recoverable device can also avoid the need for an electrical supply to power an electric pump; it can also be significantly lighter than an electrical pump. It is also believed to be the first practical implementation of generation of TNP within the wound dressing. The wearer is not limited to a hospital nor is bedbound, and may perform most if not all of his or her usual daily activities with mobility unimpaired by wearing the wound dressing 10.

The resiliently recoverable device 20 may be preset in the deformed state during manufacture of the wound dressing 10, and released upon application of the wound dressing to a wound site 12. However, a particularly preferred feature of the illustrated embodiments described later is that the resiliently recoverable device 20 be manually manipulatable to its deformed state by a user (e.g., a patient or a caregiver) to prime the wound dressing ready for TNP use. Even more preferably, the manual manipulation may be repeated as often as desired while worn, enabling the user to reprime the wound dressing for prolonged generation of TNP should the negative pressure begin to subside. Optionally, the first compartment 22 can be reopenable from the second compartment 34 such that the user or healthcare professionals can gain access to the replaceable exudate dressing 28. Such a feature provides advantages of wound inspection and dressing replacement in case of users with heavier wound exudates. A reopenable coupling may be provided, for example, between the first and second compartments, or as part of the second compartment. The reopenable coupling can be an adhesive coupling, or a mechanical (e.g. interference fit) coupling, or a magnetic coupling.

The resiliently recoverable device 20 may be compressible or expandable. In the illustrated embodiments, the resiliently recoverable device 20 expands progressively from a resiliently compressed state. The resiliently recoverable device 20 is arranged inside the first compartment 22 to urge expansion of the first compartment 22 as the resiliently recoverable device 20 expands. Disposing the resiliently recoverable device 20 within the first compartment 22 efficiently utilizes available space, and avoids having to otherwise couple the resiliently recoverable device 20 externally of the compartment 22. The resiliently recoverable device 20 may optionally be attached to a wall or interior surface of the first compartment 22, or the resiliently recoverable device 20 may be captive but loose within the first compartment 22. In an alternative form, the resiliently recoverable device 20 could be configured to contract from a resiliently expanded state; the resiliently recoverable device 20 may then be arranged outside the first compartment 22 and coupled to the first compartment 22 to urge expansion of the first compartment 22 as the resiliently recoverable device 20 contracts.

The resiliently recoverable device 20 may take any of a number of different forms. The resiliently recoverable device 20 may comprise a resiliently deformable member 24, for example, a resiliently deformable (e.g., compressible) foam member, or a resiliently deformable spring. A foam member is preferred, because the foam may be generally soft and compliant, enabling the wound dressing 10 to conform to the skin topology, and be comfortable to wear. Example foam materials include polyester polyurethane, polyether polyurethane, foam rubber, PE, PP, EVA, etc. The resiliently deformable member 24 may optionally be contained within a flexible, liquid- impermeable housing (not shown) to prevent exudate from entering the resiliently deformable member 24. The housing may be gas permeable.

The wound dressing 10 further comprises at least one exudate handling material 28, for managing wound exudate within the wound dressing. The exudate handling material 28 may be a single layer (e.g., as in Fig. 1 ), or it may comprises plural distinct layers 28a, 28b (Fig. 1 ) or 28a, 28b and 28c (Fig. 2). Layers may optionally be separated by a perforated sheet 30 (Fig. 2) if separation is desired.

For example, the exudate handling material 28 may include an absorber 28a for absorbing and storing exudate. Example absorbers include any one, or a combination of any two or more, selected from: hydrofiber dressing (explained in more detail below); gauze; hydrophobic or hydrophilic foam; sponge; superabsorbent(s); hydrocolloid(s); hydrogel(s). The absorber 28a may have a wicking characteristic for wicking exudates away from the wound interface region 14, for example, wicking upwardly and/or laterally.

Additionally or alternatively, the exudate handling material 28 may include a distinct wicking material or layer 28b for wicking exudates away from the wound interface region 14, for example, wicking upwardly and/or laterally. If a wicking layer 28b is used in combination with absorber 28a, the wicking layer 28b is preferably the closer to the wound interface region 14. The material of the wicking layer may be hydrophobic. Example materials for the wicking layer 28b include polyester fleece or a blend of cellulose and polyester fiber.

Additionally or alternatively, the exudate handling material 28 may include a primary dressing layer 28c. The primary dressing layer 28c comprises a gel, or interacts with exudate to form a gel, to maintain a partially moist environment in the vicinity of the wound site 12, while allowing excess exudate to be drawn away into the wound dressing. Example materials for the primary dressing layer 28c include one or more silicone gels, and/or hydrofibers. An example hydrofiber is sodium carboxymethylcellulose (NaCMC), for example, available from ConvaTec under the trade name "Aquacel™". Optionally, the primary dressing layer 28c may include an antimicrobial agent. For example, the hydrofiber may include silver ions as an antimicrobial agent, and such a hydrofiber is available from ConvaTec under the trade name "Aquacel Ag™". If used in combination with other layers 28a and/or 28b, the primary dressing layer 28c is preferably the closest at or to the wound interface region 14.

If desired, the wound interface region 14 of the dressing 10 may comprise a perforated contact sheet or layer 32 for contacting the wound site 12. However, the perforated contact sheet 32 may be omitted especially if the primary dressing layer 28c is used.

The absorption material 28 is disposed to communicate directly or indirectly with the wound interface region 14. The absorption material 28 may optionally be arranged within the same first compartment 22 that generates negative pressure. However, in the illustrated embodiments, it is preferred that the absorption material 28 be arranged within a second compartment 34 that communicates directly or indirectly with the wound interface region 14, and with the first compartment 22. The second compartment 34 is, for example, arranged physically between the first compartment 22 and the wound interface region 14. The provision of the second compartment 34 enables the exudate handling function and negative pressure generating function to be separated. Use of distinct compartments 22 and 34 also facilitates the possibility of a user manually manipulating the resiliently recoverable device 20 to prime the dressing 10 for TNP and/or reprime the resiliently recoverable device 20 to prolong application of TNP should the negative pressure begin to subside. Optionally, the first compartment 22 can be reopenable from the second compartment 34, or the second compartment itself can be reopenable, such that the user or healthcare professionals can gain access to the replaceable exudate dressing 28.

In the illustrated embodiments, the user manipulates the resiliently recoverable device 20 by squeezing the device 20 and/or the first compartment 22. Referring to Figs 3 and 4, squeezing may be done by pressing on the resiliently recoverable device 20 before (or after) the wound dressing 10 has been applied to the wound site 12. Squeezing the first compartment 22 compresses its volume, pressurizing the mass of air within the first compartment 22. At least one valve 40 automatically controls airflows to vent positive pressure within the first compartment 22 to atmosphere during the compression, and/or to apply suction (negative pressure) from the first compartment 22 to the second compartment 34 as the resiliently recoverable device 20 recovers its shape. Valve 40 is a pressure relief valve coupled to the first compartment 22. Valve 40 is responsive to pressure differential between the first compartment 22 and external atmosphere, and opens to vent pressure from the first compartment 22 when greater than atmospheric pressure. Valve 40 closes when the pressure within the first compartment 22 is negative compared to atmosphere, thereby defining a closed volume within the dressing 10 subjected to negative pressure as the recoverable member 20 recovers.

Valve 42 is a suction valve coupling the first and second compartments 22 and 34. The suction valve is responsive to pressure differential between the first and second compartments 22 and 34, and opens to permit application of negative pressure from the first compartment 22 to the second compartment 34. Valve 42 closes when the pressure within the first compartment 22 is greater than in the second compartment 34. Valve 42 is optional, but highly preferred. Valve 42 is not essential to the generation of negative pressure within a closed volume, but is preferred in order to avoid air being driven temporarily into the second compartment 34 instead of venting outside the wound dressing 10. Valve 42 can also avoid application of positive pressure to the wound site 12 and the exudate handling material 28. Positive air pressure within the first compartment 22 therefore vents through the valve 40 without being applied to the wound site 12.

If desired, a pressure gauge or other pressure state indicator may be provided for indicating the level of negative pressure within the wound dressing 10.

Optionally, a negative pressure relief feature (not shown) may be provided coupled to either the first compartment 22 or the second compartment 34. The negative pressure relief feature would act as a safety feature by opening should the magnitude of the negative pressure exceed a desired threshold safe for TNP, venting the negative pressure atmosphere. The negative pressure relief feature could either be implemented as a discrete valve, or it may be frangible portion of the wound dressing 10.

The wound dressing 10 may further comprise a flexible housing 36 enclosing, or at least partly defining the first and second compartments 22 and 34. The flexible housing may be made of non-permeable material as the wound cover layer. The flexible housing may contain the exudates within the wound dressing 10. The flexible housing 38 may be of flexible plastics film, flexible polyurethane foam, polyurethane foam, polyurethane foam laminated with a film, or low durometer polyethylene foam.

In the first and second embodiments, the first and second compartments 22 and 34 may generally overlie each other. The resiliently recoverable device 20 may be of about the same size as the dimensions of the wound dressing 10, such that the resiliently recoverable device overlies all of the wound interface region 14.

In a further alternative embodiment illustrated in Figs. 5 and 6, the resiliently recoverable device 20 is arranged so that at least the majority of the resiliently recoverable device 20 does not overlie the wound interface region 14. Optionally, at least the majority of the resiliently recoverable device 20 overlies the seal 16. In the illustrated form, substantially none of the resiliently recoverable device 20 overlies the wound interface region 14, although there may be some partial overlap according to the desired design. Such an arrangement avoids or reduces application of pressure on to a wound site 12 when a user squeezes the resiliently recoverable device 20. The resiliently recoverable device 20 may optionally be shaped with a closed loop (or ring) form extending around a central aperture 50, in which the volume of the exudate handling material 28 is received. For example, the resiliently recoverable device may have a ring form with a geometry to suit the shape of wound dressing 10. In the illustrated form, the wound dressing 10 has a rectangular form, and the resiliently recoverable device 20 is of rectangular ring form. The central aperture is also rectangular, to match a similar shape of wound interface region 14 and wound exudate handling material 28. The compartments 22 and 34 have shapes to match, and are separated laterally from each other. Only a single pressure-relief valve 40 and suction valve 42 are shown, but it will be appreciated that plural valves of one or both types may be implanted as desired.

Additionally or alternatively, the first compartment 22 can be a stand- alone unit in the proximity to wound dressing 10 through a communication channel between the first compartment 22 and the second compartment 34. In this case, the first compartment does not overlap a majority of the footprint of wound dressing 10, although the first compartment can be still fastened to a portion of skin through a skin adhesive. Such a design could provide additional feature in the ease of use to generate the negative pressure with a resiliently recoverable device.

Although the preferred embodiments illustrate only a single resiliently recoverable device 20 and respective compartment 22, it will be appreciated that plural resiliently recoverable devices 20 and respective compartments 22 may be provided, each having a respective pressure relief valve (or valves) 40 and coupled to the second compartment 34 via a respective suction valve (or valves) 42.

The present invention, particularly as illustrated in the preferred embodiments, can enable a wound dressing to be provided avoiding many of the disadvantages of the prior art. In particular, the invention can provide a TNP wound dressing having one or more of the following advantages:

(i) generation of TNP at the wound dressing without coupling to an external suction source;

(ii) avoiding a need for an electrical power supply; (iii) the dressing can be worn by a mobile patient and/or used in environments other than hospitals and bedside care;

(iii) the dressing permits the wearer to perform his or her usual daily activities while wearing the dressing;

(iv) lightweight;

(v) compact;

(iv) inexpensive to manufacture;

(v) intuitive and easy to use by members of the public.

The foregoing description is illustrative of preferred forms of the invention and does not limit the scope of the invention. Many modifications, improvements and equivalents may be used without departing from the principles of the invention as claimed.

Claims

1 . A wound dressing comprising:

a wound interface region;

a seal for forming a substantially airtight seal between the wound dressing and skin in a region surrounding a wound; and

a resiliently recoverable device carried by or in the wound dressing, for generating a negative pressure within at least a portion of the wound dressing as the resiliently recoverable device recovers resiliently from a deformed state.

2. The wound dressing of claim 1 , wherein the resiliently recoverable device is resiliently deformable to the deformed state in response to application of manual deforming force in order to prime the wound dressing for generation of negative pressure.

3. The wound dressing of claim 1 , further comprising a first compartment containing the resiliently recoverable device, and a second compartment for receiving wound exudate, the second compartment communicating directly or indirectly with the wound interface region.

4. The wound dressing of claim 3, wherein the first compartment is expandable in volume as the resiliently recoverable device recovers from the deformed state.

6. The wound dressing of claim 3, further comprising a suction valve coupling the first and second compartments, the suction valve being responsive to pressure differential between the first and second compartments, and opening to permit application of negative pressure from the first compartment to the second compartment.

7. The wound dressing of claim 3, wherein the resiliently recoverable device is resiliently deformable to the deformed state in response to application of manual deforming force in order to prime the wound dressing for generation of negative pressure, and the first compartment is collapsible in volume as the resiliently recoverable device is deformed.

8. The wound dressing of claim 7, further comprising a pressure relief valve coupled to the first compartment, the pressure relief valve being responsive to pressure differential between the first compartment and external atmosphere, and opening to vent pressure from the first compartment when the pressure inside of the first compartment is greater than atmospheric pressure.

9. The wound dressing of claim 3, further comprising a reopenable coupling for at least one of the first compartment and the second compartment. 10. The wound dressing of claim 9, wherein the reopenable coupling is selected from: an adhesive coupling; a mechanical coupling; a magnetic coupling.

1 1 . The wound dressing of claim 9, wherein the reopenable coupling permits the exudate dressing to be changed.

12. The wound dressing of claim 3, wherein the first compartment and the second compartment are connected by a narrow channel to allow for pressure communication.

13. The wound dressing of claim 1 , further comprising absorbing material for absorbing wound exudate.

14. The wound dressing of claim 1 , further comprising wicking material for wicking excess exudate away from the wound interface region.

15. The wound dressing of claim 1 , further comprising gel or gel-forming material providing a primary dressing layer for exudate.

16. The wound dressing of claim 1 , wherein the resiliently recoverable device is configured to recover by expanding from a resiliently compressed state. 17. The wound dressing of claim 1 , wherein the resiliently recoverable device comprises a resiliently recoverable member.

18. The wound dressing of claim 13, wherein the resiliently recoverable member comprises open cell foam.

19. The wound dressing of claim 1 , wherein the resiliently recoverable device at least partly overlaps the wound interface region.

20. The wound dressing of claim 1 , wherein at least a majority of the footprint of the resiliently recoverable device does not overlap the wound interface region.

21 . The wound dressing of claim 1 , wherein the seal comprises skin compatible adhesive for bonding to skin around the wound.

22. A wound dressing comprising:

a wound interface region;

a seal for forming a substantially airtight seal between the wound dressing and skin in a region surrounding a wound;

a cover layer;

a manually manipulatable device disposed between the seal and the cover layer for generating in response to, or recovering from, manual manipulation, a negative pressure at the wound interface region. 23. The wound dressing of claim 22, wherein the manually manipulatable device is manipulated by compressing or squeezing the manually manipulatable device.

24. The wound dressing of claim 22, wherein the manually manipulatable device comprises a resiliently recoverable device that recovers resiliently following deformation by manipulation. 25. The wound dressing of claim 24, wherein the resiliently recoverable device generates a restoring force in response to deformation, the restoring force urging expansion of a first compartment, for generating a drop in air pressure within the first compartment. 26. The wound dressing of claim 25, further comprising a pressure relief valve coupled to the first compartment, the pressure relief valve being responsive to pressure differential between the first compartment and external atmosphere, and opening to vent pressure from the first compartment when greater than atmospheric pressure.

27. The wound dressing of claim 26, further comprising a second compartment containing exudate handling material and communicating directly or indirectly with the wound interface region, the second compartment being coupled to the first compartment for application of negative pressure from the first compartment to the second compartment.

28. The wound dressing of claim 27, further comprising a suction valve coupling the first and second compartments, the suction valve being responsive to pressure differential between the first and second compartments, and opening to permit application of negative pressure from the first compartment to the second compartment.

29. The wound dressing of claim 27, further comprising a pressure relief valve coupled to the first compartment, the pressure relief valve being responsive to pressure differential between the first compartment and external atmosphere, and opening to vent pressure from the first compartment when the pressure inside of the first compartment is greater than atmospheric pressure.

30. The wound dressing of claim 22, wherein at least a majority of the manually manipulatable device is disposed so as not to overlie the wound interface region. 31 . A portable negative pressure generation unit for a wound dressing, comprising:

a resiliently recoverable device for generating a negative pressure as the resiliently recoverable device recovers resiliently from a deformed state; and

a negative pressure communication interface for communicating the negative pressure to the wound dressing.

32. The portable negative pressure generation unit of claim 31 , further comprising a skin compatible adhesive for mounting the unit to a wearer's skin.

33. The negative pressure generation unit of claim 31 , further comprising a coupling for coupling the unit to a wound dressing such that the unit is carried by the wound dressing.

34. An assembly comprising:

a wound dressing;

a negative pressure generation unit coupled to the wound dressing for applying negative pressure thereto;

skin-compatible adhesive enabling the assembly to be mounted to a wearer's skin, whereby the wound dressing and negative pressure generation unit are carried by a wearer.