GB2409412A

GB2409412A - Hyperbaric wound treatment device

Info

Publication number: GB2409412A
Application number: GB0329661A
Authority: GB
Inventors: Paul Howard Lowing
Original assignee: Johnson and Johnson Medical Ltd
Current assignee: Johnson and Johnson Medical Ltd
Priority date: 2003-12-22
Filing date: 2003-12-22
Publication date: 2005-06-29
Also published as: GB0329661D0

Abstract

The present invention provides a device for administering a hyperbaric treatment to a wound comprising: <SL> <LI>(a) a gas-tight cover (2) for covering the wound and for enclosing a volume of gas at hyperbaric pressure over the wound; <LI>(b) a seal (3) for sealing a peripheral region of said cover to tissue surrounding the wound; <LI>(c) a gas inlet (8) for introducing a gas at hyperbaric pressure into said enclosed volume; <LI>(d) a wound fluid collector (12) for collecting fluid exuded into said enclosed volume by the wound; and <LI>(e) a wound fluid outlet (10) for transferring wound fluid from the wound fluid collector (12) out of the enclosed volume. </SL> Also provided are methods of use of such devices to treat wounds. The cover 2 may be transparent and sealed with adhesive 4. The collector may be a tube 13 having multiple openings 15 and an absorbent material 12 of sponge or foam. Material 12 may hold one or more therapeutic substances. The outlet 10 may be provided with a valve 11 and a gas pressure release valve may be provided (17 fig 4).

Description

24094 1 2

HYPERBARIC TREATMENT DEVICE

FIELD OF INVENTION

The present invention relates to hyperbaric devices for treating wounds and lesions on a patient's body by bringing a therapeutic gas under pressure into contact with the area to be treated.

BACKGROUND OF THE INVENTION

The effect of oxygen tension on wound healing has been extensively studied.

Wound healing is dependent upon several processes including proliferation of fibroblasts, collagen synthesis, angiogenesis and re-epithelialization. These processes are affected by the subcutaneous partial pressure of oxygen (PO2). For example, supplemental oxygen can lead to increased rate of collagen deposition, epithelialization and improved healing of split thickness grafts. Increased subcutaneous PO2 has also been shown to improve bacterial defences.

Many skin sores, ulcers, wounds and burns do not heal properly because there is a severe depletion of oxygen reaching these affected areas due to deterioration of the associated blood microcirculation. Conventionally, many of these skin diseases have been treated by various methods of administration of oxygen gas, either through inhalation of the gas, or by topical treatment with the gas.

It is now known that continuous flow of oxygen is not necessary, and that effective hyperbaric treatment can be obtained by using a single adequate stationary charge of oxygen that is retained in a chamber in contact with the wound for the treatment period. Unlike the continuous flow type devices, these devices do not need to be continuously attached to the gas supply during treatment, enabling mobility of the patient.

Many wounds produce significant amounts of wound fluid exudate. It is known that a moist wound environment promotes wound healing, but pooling of wound fluid should be avoided since it can result in undesirable leakage of the wound fluid and maceration of skin adjacent to the wound.

SUMMARY OF INVENTION

In a first aspect of the present invention, there is provided a device for administering a hyperbaric treatment to a wound, said device comprising: (a) a gas-tight cover for covering the wound and for enclosing a volume of gas at hyperbaric pressure over the wound; (b) a seal for sealing a peripheral region of said cover to tissue surrounding the wound; (c) a gas inlet for introducing a gas at hyperbaric pressure into said enclosed volume (d) a wound fluid collector for collecting fluid exuded into said enclosed volume by the wound; and (e) a wound fluid outlet for transferring wound fluid from the wound fluid collector out of the enclosed volume.

In a second aspect of the present invention, there is provided a wound treatment system comprising a hyperbaric device according to the present invention and a gas source for charging the hyperbaric device.

The present invention affords a localised hyperbaric device which is capable of removing wound exudate from the wound without removal of the device. This has the advantage that the device may be securely affixed to the area requiring treatment and left in place for a treatment period. Cleaning the wound, re- charging with therapeutic gas and/or removal excess exudate do not necessitate removal of the device.

The gas-tight cover is preferably substantially oxygen diffusion resistant, most preferably substantially oxygen impermeable. The cover may be formed from a single sheet or may be a multiple-layered laminate sheet. The cover may be formed from a flexible and/or resilient sheet material. The cover is preferably made of a thin, flexible, conformable, resilient, supple material that can flex or bend to conform to irregular surfaces or contours, such as those of anatomical body parts.

At least the periphery of the cover comprises a seal capable of fixing and sealing the cover to the skin. The seal may be formed integrally with the cover or may be secured thereto. The seal suitably comprises an adhesive material.

Suitably, the cover material may comprise a blistered (e.g. thermoformed) area to accommodate a predetermined volume of gas. Alternatively, the cover material may be formed with a bag or sack portion to accommodate a predetermined volume of gas. Preferably, the blistered region (or bag or sack) is located towards the center of the cover and is surrounded by the annulus, margin or frame of the seal.

The present invention suitably exposes the wound area in the skin to therapeutic gas. This allows the therapeutic gas to act directly on the wound area while also allowing the seal to overlay a maximum area of undamaged adjacent skin.

The device according to the invention may be configured in any convenient size, for example from about 1cm-30cm in diameter or diagonal dependent on the intended treatment. The device may be designed to cover a square, rectangular, ovoid or circular or irregularly shaped treatment area as desired.

The cover can be transparent to permit visualization, or it can be opaque. The cover material or a portion thereof is preferably transparent and may be planar, or may be formed by nonelastic stretching or thermo- forming with a blister, bag or sack over the treatment area. The blister, bag or sack is used to accommodate a volume of therapeutic gas but can also serve to retain a dressing material or fluid reservoir therein. In such an arrangement where the dressing/fluid reservoir is not present, preferably the adhesive does not extend over the treatment area.

The cover is typically made from synthetic polymers and non-woven and woven materials which are capable of being formed into continuous films by casting, extrusion or other known film making processes. The cover preferably comprises any suitable plastic, polymer film, nonwoven material, weave or the like, or combination thereof, known in the art. Suitable examples include polyolefins such as polypropylene, ethylene acrylic acids, ethylene vinyl acetates, polyvinylchlorides, polyether sulfones, polyether ketones, polyether urethanes and polyurethanes.

The cover material preferably comprises a compound, preferably a polymer, more preferably a polymeric layer or film, with low-oxygen permeability, which can be formed into a continuous film of sufficient flexibility for use as a device according to the present invention. Preferably, the cover or a layer incorporated into the cover suitably has an oxygen permeability of less than about 15cm3/cm2/mm/24hrs, preferably less than about 5cm31cm21mml24 furs, preferably less than about 1 cm3/cm2/mm/24hrs. In particular, films of polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, high-density polyethylene and high-density polypropylene are suitable for use as a low-oxygen permeability cover material or as a material forming part of the cover. Alternatively or in addition, the cover material may comprise a flexible metal sheet or foil.

The cover is suitably constructed from or comprises a material having,a high tensile strength to resist breakage.

The term "hyperbaric" refers to a pressure or partial pressure greater than ambient pressure or partial pressure. Generally, the total pressure of the gases inside the wound treatment volume is higher than ambient atmospheric pressure. Suitably it is from about 1% to about 100% higher, preferably from about 2% to about 10% higher, for example from about 3% to about 5% higher. In some embodiments, only the partial pressure of a particular therapeutic gas, e.g. oxygen, is higher than in the ambient atmosphere. The pressure is suitably provided by a therapeutic gas, preferably oxygen. Additionally or alternatively, other gases, for example nitrogen, may be used.

The pressure is suitably supplied by a gas source which is connectable to the gas inlet, thereby providing an increased pressure beneath the cover when in use.

The gas source may be in the form of a pump or a canister of gas.

For neovascularization and wound healing, the gas is preferably substantially pure oxygen gas at pressures of up to 3 atmospheres. Oxygen pressures of about 1.02-1. 10 atmospheres are preferably used, more preferably 1.03-1.04 atmospheres.

Because of problems associated with excess oxygen exposure, patients may be treated for comparatively short periods, for example 20 minutes twice a day to about four hours once a day for up to four days with a three or four day rest period per week. However, longer and/or more frequent treatment periods may be prescribed. Preferably, the device of the present invention may be applied to a wound area and be used to continuously treat a wound until substantial healing of the wound has taken place. This may be for a continuous period of 2-10 days or more.

Hyperbaric oxygen therapy requires a balance between enough therapeutic gas to cause revascularisation etc., and avoiding excess therapeutic gas exposure. It is therefore unnecessary to provide for oxygen through-flow since this not only unnecessarily complicates the device and support surfaces associated with it, but also tends to increase oxygen toxaemia.

A single charge of therapeutic gas such as oxygen is preferred for therapeutic purposes. However, a plurality of gas charges may be used, either to replace the gas beneath the cover, or to supplement it.

The gas inlet preferably comprises a manually operable valve or a pressure activated valve, for example, a one-way valve. The gas supply may be connected to the gas inlet in order to supply the requisite gas pressure to the treatment area beneath the cover. The gas supply may remain connected to the gas inlet, thereby providing substantially constant supply of gas or simply maintaining the gas pressure beneath the cover.

Alternatively, the gas supply may be disconnected from the gas inlet. In this preferred embodiment, the gas pressure beneath the cover is maintained by the operation of the gas inlet valve and the cover seal which forms an air-tight seal with the skin or tissue surrounding the treatment area.

The gas inlet preferably comprises a conduit formed from the same or different material to the cover. The gas inlet may be formed integrally with the cover or may be formed separately and secured to the cover. The gas inlet preferably comprises a proximal and distal end with openings at each end, the ends being capable of being brought into fluid contact with one another. Preferably the valve is provided within the gas inlet conduit which enables fluid contact between the ends of the conduit.

Where the gas inlet is formed separately to the cover, it is preferably sealed into the cover in a gas tight fashion, optionally by the use of an adhesive.

In a preferred embodiment of the invention the conduit is comprised of a length of a flexible transparent pharmacologically acceptable plastics tubing. In such an arrangement an aperture is formed in the cover material in the treatment area, the end of the conduit is passed through said aperture and the conduit is secured to the exterior face of the cover material. A valve may be secured to the distal end of the conduit or within the conduit. Preferably, the valve is adhesively secured to the conduit. Application of the valve may take place before or after installation of the conduit in the cover.

The hyperbaric device of the present invention may be provided with a hand portable gas source, for example, a canister of therapeutic gas such as oxygen, which allows the hyperbaric device to be charged with a desired pressure without necessarily requiring the use of a pressure gauge. A pressure gauge can be applied to a hand-portable gas source and arranged such that a desired gas pressure can be read off from a desired value.

The hand-portable gas source may be a one-shot canister with an outlet adapted for interconnection with the gas inlet and means being provided to release the pressurized therapeutic gas in the one-shot canister at least to the gas inlet.

There is sufficient gas in the one-shot canister to fill the treatment area once. The one-way valve suitably prevents outgress of gas through the gas inlet.

Further, the hand-portable gas source or other device may be provided with means to supply the therapeutic gas to a treatment area at a predetermined pressure value, for example 1-3 atmospheres, preferably about 1.02-1. 10 atmospheres, more preferably 1.03-1.04 atmospheres.

Alternatively the hand-portable gas source may be of the multi-shot type, in which case a manually or pressure actuated valve on said gas source may be utilised to control the therapeutic gas supply and preferably its pressure via the gas inlet to the treatment area. Means may be provided to prevent seepage of the gas via the gas inlet in use when the gas source is removed. This may, as previously stated, be effected by means of the use of one-way valves within the device.

The seal is preferably formed from a medically acceptable adhesive material and may be coated on a surface of the cover or may comprise sheet material forming a surface or part of a surface of the cover. Preferably, the adhesive is in the form of a layer or film which may be applied to a predetermined portion of the cover material. The adhesive layer/coaVfilm is preferably 0.1 mm to 0.65 mm thick and preferably about 0.45 mm thick.

The adhesive material of the seal may be formed from a flexible/resilient sheet coated on both surfaces with an adhesive.

The adhesive coating may be selected from any number of commercially available medical grade adhesives known in the art. The adhesive is suitably dermatologically acceptable and skin adhesive at room temperature as well as at the skin temperature of patients. The adhesive may be prepared from any combination of homopolymers, oligomers or blends thereof to produce a polymeric composition preferably selected from the group consisting of polyacrylates, polyolefins, silicone adhesives, polyvinyl ethers, polyesters, and polyurethanes.

The adhesive properties of medical grade adhesives can be adjusted by the addition of a greater amount of cross-linking additives and/or by utilizing different coating weights and/or viscosities of the adhesive materials.

The adhesive coating may contain other components or reagents for performing specific desired functions, for example, tackifiers, fillers, bactericides, medicaments or other bioactive agents.

A release layer is preferably provided on the seal adhesive prior to use. The release layer may be removed prior to application of the device to the wound area.

The release layer is suitably a non-adhesive layer which forms a weak bond with the adhesive seal.

The release layer may be formed in a two or three layer, partially overlapped configuration, whereby the removal of one such layer allows a portion of the adhesive face to be exposed for contact with the skin about the wound. This arrangement allows the device to be correctly orientated relative to the wound and secured in this orientation while the other release layer or layers are removed so that the device is correctly orientated on the skin without folds or tucks.

The release layer is preferably silicone release paper, and is releasably secured to protect the skin contacting portion of the seal prior to application of the device to a treatment site. Alternatively, the release layer can be made of polyethylene, polypropylene or polyester which is coated with a releasing agent such as silicone or a fluoropolymer. Preferred release layers are silicone coated.

The device of the present invention may be secured in place by the application of strapping or wrapping to the device. The strapping or wrapping material preferably secure the device around a limb or to a portion of the patients body. Any suitable material may be used to strap the device to the patient. This may be used to S improve the seal between the device and the patient.

The wound fluid collector may be an absorbent material capable of absorbing wound exudate. The absorbent material may be attached to a part of the cover sheet and/or it may be attached to the wound fluid outlet. The absorbent material is preferably porous, for example a sponge-like or foam-like material. The absorbent material may be placed in the wound or in a position overlying the wound. The absorbent material is preferably sufficiently porous to permit gas flow through the absorbent material to the wound. In use, the absorbent material is preferably in direct contact, preferably liquid contact with the wound.

The absorbent material is typically provided in the form of a sheet. The area of the absorbent sheet is typically in the range of from 1cm2 to 200cm2, more preferably from 4cm2 to 100cm2. The uncompressed thickness of the layer is typically from about 2mm to about 25mm, for example from about 5mm to about 1 5mm. The free (uncompressed) liquid absorbency measured for physiological saline may be in the range of 5 to 30 g/g at 25 .

The absorbent material may comprise any of the materials conventionally used for absorbing wound fluids, serum or blood in the wound healing art, including gauzes, nonwoven fabrics, superabsorbents, hydrogels and mixtures thereof.

Preferably, the absorbent material comprises a layer of absorbent foam, such as an open celled hydrophilic polyurethane foam prepared in accordance with EP-A- 0541 391, the entire content of which is expressly incorporated herein by reference. In other embodiments, the absorbent layer may comprise a nonwoven fibrous web, for example a carded web of viscose staple fibers. In other embodiments, the absorbent material may comprise or consist essentially of a freeze-dried sponge material, for example a freeze-dried collagen sponge, or a freeze-dried sponge of collagen mixed with alginate (for example the material described in US-A4614794 and available under the Registered Trade Mark FIBRACOL from Johnson & Johnson Medical Limited) , or a freeze-dried sponge of collagen mixed with oxidized cellulose (for example the material described in WO98/00180 and available under the Registered Trade Mark PROMOGRAN from Johnson & Johnson Medical Limited). In these and other embodiments the absorbent material may be bioabsorbable. However, the absorbent material preferably is not soluble in wound fluid.

The absorbent material may be pre-formed or may be formed in situ. For example, a material, preferably an absorbent material may be sprayed or coated or freeze-dried on the wound area or into the cover sheet, thereby forming a sponge or foam-like material which may be in intimate contact with the wound area.

The absorbent material may comprise part of the device of the present invention may comprise 0-10% by weight, suitably 0-5% by weight of one or more therapeutic agent. Any of the following kinds of biologically active substances can be included: medications and disinfectants as well as wound healing enhancers, e.g., a vitamin preparation, blood coagulants for battlefield applications, anti inflammatory drugs, angiogenesis promoters, antiseptic compounds, antibiotic compounds, or a source of oxygen. Among other biologically active substances are astringents, oxidants, proteolytic enzymes, collagen cross-link inhibitors such as natural or synthetic diamines, e.g., cystamine or histidine, putrescine, spermidine, cadaverine, alpha, omega diamino polyethylene or polypropylene oxide and the like, various growth factors, amino acids, macrophage stimulating factors, narcotic analgesics, anesthetics, and the like. All of the above percentages are on a dry weight basis.

The one or more therapeutic agents may be any substance suitable for the treatment of wounds, but does not include the polymer used to form the coating, which may independently promote wound healing. In certain embodiments the therapeutic agents are selected from the group consisting of antiseptics, antibiotics, analgesics, steroids and growth factors. Preferred therapeutic agents are the antimicrobials, in particular antibiotics and antiseptics such as colloidal silver, silver sulfadiazine, povidone iodine, chlorhexidine, and mixtures thereof.

Preferably, the polymeric coating material according to the present invention comprises from about 0.01% to about 20% by weight of the one or more therapeutic substances, more preferably from about 1% to about 5% by weight.

In other embodiments, the wound fluid collector may alternatively or additionally comprise a wound fluid collection manifold. That is to say, a conduit for the wound fluid having a plurality of spaced-apart inlets. For example, the collector could take the form of a perforated tube, which may extend across the wound treatment zone of the device in linear, serpentine or coiled fashion to collect the wound fluid.

In other embodiments the collector could have a dendritic tubular structure to collect wound fluid over an area of the treatment zone. Such manifold structures may for example be used alone, or may be applied to or embedded into the absorbent material as hereinbefore described.

The wound fluid outlet preferably comprises a conduit having proximal and distal ends with openings at each end, the ends being capable of being brought into fluid contact with one another. The proximal opening is normally beneath the cover, i.e. within the treatment area volume created by the seal cover and treatment area, and positioned to receive wound fluid from the collector, for example, by being directly connected to the wound fluid outlet. The proximal opening of the fluid outlet may be formed flush with the side of the cover which faces the wound in use. Alternatively, the proximal opening of the fluid outlet may extend away from the face of the cover which faces the wound in use.

The proximal opening of the fluid outlet is secured to or otherwise in direct contact, preferably liquid contact, with the wound fluid collector. Preferably the fluid outlet is capable of draining liquid (wound exudate) away from the collector and transporting the wound fluid from the collector, via a conduit, to the exterior of the device.

The fluid outlet, preferably the proximal portion of the fluid outlet, may comprise a conduit, preferably a tube. The conduit or tube may comprise a single or preferably a plurality of openings which allow ingress of fluid or connection to the wound fluid collector or to the wound fluid collection manifold. The, or each opening may comprise a filter means to prevent ingress of material which may block the fluid outlet. In one embodiment of the present invention, the conduit or tube may split into a plurality of conduits which act as tributaries to the main conduit that leads to the distal end of the fluid outlet.

In certain embodiments of the invention, the collector is a hydrophilic open-cell foam pad, and the proximal end of the wound fluid outlet is inserted into the pad.

The distal end of the wound fluid outlet is preferably positioned on the opposite face of the cover to the proximal end. The fluid outlet preferably comprises a valve or tap system, for example, a pinch valve. The valve is normally kept closed during the hyperbaric treatment. Opening of the valve or tap enables gas and/or wound exudate to be vented from the device intermittently, the liquid being expelled by the hyperbaric pressure in the treatment volume. Venting may take place either manually or automatically when the gas pressure within the applied device is too great, or where wound exudate has built up to a predetermined maximum level. After venting of the wound fluid, the valve may be closed and the device may be re-charged with gas. Venting and gas re-charge may be carried out a plurality of times.

Alternatively or additionally, a suction device, for example, a suction pump or a syringe, may be connected to the liquid outlet and used to draw fluid from the treatment area. This could be advantageous when the proximal end of the fluid outlet is in direct fluid contact with the fluid reservoir or the wound.

The device according to the present invention optionally further comprises a pressure release valve, which may be integral with or separate to the fluid outlet valve. Thus, it is possible to set the maximum gas pressure of the treatment zone to the desired treatment pressure. Preferably, the pressure release valve is not in direct communication with the means for introducing the gas. The valve may be adapted to automatically release gas from the treatment zone when the maximum pressure is exceeded, which pressure can be pre-set at the desired maximum pressure in the treatment zone. Preferably the valve is manually adjustable so that the desired maximum pressure of the treatment zone can be set accurately at the appropriate gas pressure determined by diagnosis.

The design of the pressure release valve is not critical. Many different types are suitable. For example, a ball valve or a baffle valve are envisaged. The preferred valve bodies are made of any rigid plastic, although metals such as stainless steel can be used.

Having separate pressure release valve and fluid outlet allows the gas pressure within the affixed device to be controlled separately to the removal of liquid, such as wound exudate, from the device.

The devices of the present invention are economical to manufacture and because they utilise comparatively small volumes of therapeutic gas are particularly adapted for out-patient treatment. Readily hand-portable therapeutic gas canisters may be provided for utilization with the hyperbaric device of the present invention.

The devices of this invention are useful in the treatment of conditions such as venous ulcers, diabetic ulcers, decubitis ulcers, chronic and acute wounds, post- operative lesions/wounds, haematomas, burns, skin grafts, sports injuries and frost bite. Specific conditions successfully treatable by the devices in accordance with the present invention include osteomyelitis, burns, scalds, necrotizing faciitis, pyoderma gangreneosum, refractory ulcers and diabetic foot ulcers.

The device of the present invention may also be used to clean the wound.

Removal of the device to clean the wound and/or remove excess exudate does not necessitate removal of the device. A cleaning composition, for example, an aqueous solution optionally comprising a solvent and/or a therapeutic agent as defined above, may be introduced to the device, in situ, through the gas inlet. In particular, an aqueous solution comprising one or more compounds selected from the group consisting of disinfectants, antiseptic compounds and antibiotic compounds is preferred as the wound cleaning composition. The cleaning composition may be left to reside in the device, in situ, for a period of time, or may be forced through the device by the application of pressure to the gas inlet of suction to the fluid outlet. For example, a syringe may be provided which may be used to flush cleaning fluid through the device. Venting of the cleaning composition from the device may take place through the fluid outlet or the pressure release valve, preferably the fluid outlet.

The cleaning of the device is particularly advantageous. The present device makes cleaning possible and relatively easy. The proximity of the fluid outlet to the wound surface facilitates the removal of a substantially portion, preferably substantially all of the cleaning composition from the treatment site. This has not

been possible using the prior art devices.

The device may be recharged with the therapeutic gas, preferably oxygen, after cleaning of the device.

The method of the present invention may also comprise: diagnosing the wound to determine a treatment zone desired maximum gas pressure; selecting a hyperbaric treatment device capable of receiving the therapeutic gas from a gas supply; affixing the device encompassing the wound to make a treatment zone including the wound, within which zone the gas is restricted; and introducing sufficient therapeutic gas into the treatment zone to substantially maintain the gas pressure therein at the desired pressure. This treatment is continued for the prescribed duration and repeated, if necessary, at the prescribed intervals, determined by thediagnosis. Preferably the treatment is a static charge treatment, wherein the gas is retained in the treatment zone for a prolonged period of time so that the gas supply can be disconnected giving patient comfort.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of the topical hyperbaric device of the present invention, reference is made to the drawings in which: Figure 1 is a top view of the preferred hyperbaric device according to a first embodiment of the present invention; Figure 2 is a cross-section of the device of Figure 1 along line A-A.

Figure 3 is a cross-section view of an alternative device according to a second embodiment of the present invention.

Figure 4 is a cross-section view of a device according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1, a preferred hyperbaric treatment device 1 of the present invention comprises an approximately circular sheet of flexible gas impermeable sheet material 2 that is capable of confining gas and retaining it within a volume formed between the sheet and the patient's skin, referred to as the therapeutic gas treatment zone.

The sheet material 2 comprises a peripheral seal 3 which comprises an annular layer of adhesive 4 which forms an air-tight seal with the patient's skin bordering the wound 5 (shown bordered by the hatched line 6). The sheet material is placed approximately circumferentially over the wound. The portion of the sheet within the circumferential seal 3 forms a blistered area for a volume of gas 7 between the sheet 2 and the wound 5. As mentioned above, this volume is referred to as the therapeutic gas treatment zone.

In this device, gas inlet 8 comprises a conduit having a one-way valve 9 that permits addition of gas, but precludes escape thereof. The gas inlet is adapted to connect directly with a gas supply. The gas supply may be fed directly to the gas treatment zone 7, thereby forming a volume of treatment gas, which is in direct contact with the wound area.

A wound fluid outlet 10 is shown. The outlet 10 is a soft medically acceptable plastic tube. The outlet tube 10 is provided with a tap valve 11 in the embodiment shown. However, tap 11 may be replaced by a pinch valve or other valve that can be opened to allow liquid venting from inside the treatment zone. The fluid outlet is adapted to be directly attached to a suction or drain apparatus which facilitates removal of gas and/or wound exudate from the wound area.

A pressure release valve may be incorporated in the outlet 10 but is not shown in this embodiment.

With reference to Figure 2, a cross-section view of Figure 1 is shown along line A- A. The wound is shown substantially filled with an absorbent material 12, in this case, an open cell polyurethane foam material, which readily absorbs wound exudate. The fluid outlet 10 has a tube 13 extending therefrom into the foam layer 12. The tube 13 is used to remove gas and exudate directly from the foam layer 12, thereby facilitating venting from the device through the fluid outlet 10, upon opening of tap 11. The part of the tube in contact with the absorbent foam comprises a plurality of openings 15 which allows ingress of liquid into the tube.

The diameter of the openings is such that ingress of relatively large solid material is prevented.

With reference to Figure 3, an alternative embodiment of the device shown in Figures 1 and 2 is illustrated. In this embodiment, the cover material is formed into a sack 14 rather than a blister. The sack arrangement allows for a larger volume of therapeutic gas to be enclosed within the therapeutic gas treatment zone 7.

With reference to Figure 4, an embodiment of the device according to a third embodiment of the present invention is shown. The device is similar to that shown in Figures 1 and 2. In this embodiment, however, the fluid outlet 10 has a tube 13 extending therefrom into the wound 12. The tube 13 is used to remove gas and exudate directly from the wound, thereby facilitating venting from the device through the fluid outlet 10, upon operation of tap 11. A piece of gauze 16 is provided which allows for liquid contact with the wound but prevents traumatic direct contact therewith.

A pressure release valve 17 is shown. The pressure release valve comprises a ball valve which may be set to a desirable pressure in order to allow for automatic venting of excess gas when the pre-set pressure is reached.

Claims

1. A device for administering a hyperbaric treatment to a wound comprising: (a) a gas-tight cover for covering the wound and for enclosing a volume of gas at hyperbaric pressure over the wound; (b) a seal for sealing a peripheral region of said cover to tissue surrounding the wound; (f) a gas inlet for introducing a gas at hyperbaric pressure into said enclosed volume (9) a wound fluid collector for collecting fluid exuded into said enclosed volume by the wound; and (h) a wound fluid outlet for transferring wound fluid from the wound fluid collector out of the enclosed volume.

2. The device of claim 1 or claim 2, wherein the cover comprises a blistered area to accommodate a predetermined volume of gas.

3. The device of claim 1 or claim 2, wherein the cover comprises a bag or sack portion to accommodate a predetermined volume of gas.

4. The device according to any preceding claim, wherein the cover is substantially transparent.

5. The device according to any preceding claim, wherein the seal comprises a medically acceptable adhesive.

6. The device according to claim 5, wherein the adhesive is protected by a releasable cover sheet.

7. The device according to any preceding claim, wherein the wound fluid collector comprises an absorbent material capable of absorbing wound exudate.

8. The device according to claim 7, wherein the absorbent material comprises a sponge or foam material.

9. The device according to claim 7 or 8, wherein the absorbent material comprises one or more therapeutic substances.

10. The device according to any preceding claim, wherein the wound fluid collector comprises a wound fluid inlet manifold for collecting wound fluid from a plurality of locations.

11. The device according to any preceding claim, wherein the fluid outlet is provided with a valve that can be closed to block the passage of fluid through the outlet.

12. The device according to any preceding claim, further comprising a gas pressure release valve.

13. A wound treatment system comprising: (a) a hyperbaric device according to any of claims 1 to 12; and, (b) a gas source for charging the hyperbaric device.

14. A treatment system according to claim 13, further comprising a suction device capable of operative connection with the fluid outlet.

15. A method of treating a wound comprising the steps of: (a) applying a device according to any of claims 1 to 12 to the wound; (b) introducing a gas at hyperbaric pressure into the volume between the wound and the cover through the gas inlet; and, (c) substantially maintaining said increased pressure until the wound has progressed toward a selected stage of healing.

16. The method according to claim 15, wherein the gas consists essentially of oxygen and the hyperbaric pressures is up to 3 atmospheres absolute, preferably about 1.02-1.10 atmospheres, more preferably about 1. 03-1.04 atmospheres.

17. The method according to claim 15 or 16, wherein the wound fluid outlet is provided with a valve, and the valve is opened intermittently to vent wound fluid from inside the wound treatment volume.