CA2158930A1

CA2158930A1 - Topical hyperbaric device

Info

Publication number: CA2158930A1
Application number: CA002158930A
Authority: CA
Inventors: Evelyna Dyson Cantwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-03-23
Filing date: 1994-03-17
Publication date: 1994-09-29
Also published as: EP0690734A1; NZ262475A; AU6216594A; GB9305996D0; WO1994021323A1

Abstract

The invention provides a topical hyperbaric device (1.20) for wound healing adapted to retain a charge of of therapeutic gas over a treatment period comprising a gas diffusion resistant flexible and/or resilient sheet material (3.31) including an adhesive face adapted to affix to the skin, said adhesive face surrounding a treatment area (16.30), at least one release layer (4.23) disposed over said adhesive face, and a conduit (5.25) for the supply of the therapeutic gas to the treatment area; wherein either the sheet material is formed of a generally planar sheet (3) and the adhesive layer is disposed upon the peripheral underside portion of the sheet, said release layer (4) at least overlaying said adhesive face, or the sheet material (20) is in the form of an inflatable bag, and in that the adhesive layer is disposed upon the peripheral underside portion at least of the portion of the bag adjacent to the treatrnent area (30), the edge portion (24) further supporting an external pressure ring adjacent the treatment area independent of the adhesive layer, which ring allows pressure to be exerted toward the interface between the skin (28) and the adhesive layer (22) in use.

Description

WOg4/2~ PCT/GB94/00542 ~8930 "

TOPICAL HYPERBARIC DEVICE

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

Hyperbaric apparatus for the treatment of open wounds and lesions by application thereto of a therapeutic gas such as oxygen, with or without pharmacologically acceptable additives, is generally known, for example from US-A-5154697 and US-A-4801291. Specifically it has been discovered that the treatment of open lesions and wounds in a hyperbaric chamber with oxygen promotes granulation, raises capillary blood oxygen levels, and elevates the Redox potential thereby suppressing bacterial growth.

In the above-identified prior art, a collapsible topical hyperbaric apparatus is revealed comprising a shell defining a substantially closed internal chamber arrangeable between an expanded and a collapsed configuration, said shell having an opening therethrough communicating with said internal chamber, a ring within said internal chamber secured to said shell about said opening, said internal ring about said opening being capable of conforming to a shaped surface of the patient's body and adhering thereto, gas-introducing means for introducing a therapeutic gas into the internal chamber for expanding said shell from a collapsed to an expanded configuration and pressure relief means to control flow rate thereby to therapeutically treat a portion of the patient's body.

~0 These arrangements were provided with strap means for securing the hyperbaric apparatus to the body so that the adhesive means retained a hermetic seal during the treatment period. Generally the means for securing the W094/2~ PCT/GB94/00542 21589~ 2 hyperbaric apparatus to the body is a strap or band, or other means of compressing the device onto the body.

As stated in the prior art a good seal between the skin adjacent the wound and the adhesivè layer is important otherwise the oxygen or other therapeutic gas will tend to leak from the device.

Previously, especially in the prior art, it was thought necessary to provide for a through flow of therapeutic gas such as oxygen in order to achieve good therapeutic results. However, for reasons which are described below, this arrangement is now not only superfluous but counter-productive, since it tends to induce oxygen toxaemia caused by excessive exposure to hyperbaric oxygen, where oxygen is the therapeutic gas. Thus in the prior art devices a certain level of leakage was in fact permissible especially when the hyperbaric device was adhered to the skin without a strap or band to hold the same down. In practice in order to utilise the through flow device some means of circulating the oxygen is required and this means that the device is only utilisable in a hospital environment.

Good adherence of the device to the skin is also a function of the adhesive used. However, another important factor lies in the design of the chambers. If reference is made to Figure 3 of US-A-5154697 and Figure 4 of US-A-4801291 it will be seen that once the hyperbaric device has been inflated with therapeutic gas, it is no longer possible to apply direct pressure to the sealing area.
Thus, once the device has been positioned and inflated, further attempts to perfect sealing can only be effected by applying overall pressure to the inflated device rather than by specific point loading on a desired portion of the adhesive band.

W094/2~ PCT/GB94/00542 21~8930 This situation becomes more important when lower volumes of therapeutic gas are available i.e. when no significant through flow of gas is envisaged after application, or when only a limited quantity of therapeutic gas is available.

One object of the present invention, therefore, is to provide an arrangement allowing said adhesive layer to be resealed during use without affecting the inflated sheet material adversely.

Morphologically the most beneficial effects of hyperbaric gas treatment, and particularly hyperbaric oxygen treatment, is the stimulation of endothelial cell proliferation and generation of new blood capillaries. New blood capillaries can in fact be seen by with naked eye during successful treatment as early as two days after the commencement thereof. These new capillaries are stimulated in mild hypoxia and in practice at pressures of up to 1.03 to 1.04 atmospheres for a predetermined period. Above and below this range of values the wound is not beneficially effected. ~xygen toxicity is a condition resultant from excess oxygen exposure and results in distortion of the Krebs cycle which directly or indirectly leads to degeneration of the endothelial cells and destruction of newly formed capillaries stimulated by the hyperbaric therapy.

Another aspect of the present invention is to be found in the requirement that whereas the wound area in the skin is exposed to therapeutic gas, unaffected areas are covered ~ preferably by the adhesive layer. This allows the therapeutic gas to act directly on the wound area while also allowing the adhesive to overlay a maximum area of undamaged adjacent skin.

W094/2~ PCT/GB94/00542 21~89~ 4 Another object, therefore, is to provide a topical hyperbaric device which can be readily adapted to locate precisely over an irregularly shaped wound so that (a) the adhesion of the device to the skin is not unnecessarily impaired or reduced so that excess leakage of therapeutic gas is avoided.

It has recently become apparent that for neo-vascularization and wound healing, oxygen pressures of about 1.03-1.04 atmospheres are required rather than the 2-3 atmospheres previously used. Also, because of the problems associated with excess oxygen exposure, it is usual to treat patients 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. Even so, some toxicity effects may be observed after eight weeks of such a regimen.

It follows that hyperbaric oxygen therapy requires a delicate balance between enough therapeutic gas to cause revasculisation etc., and avoiding excess therapeutic gas exposure. It is therefore both unnecessary and unwise 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.

For these reasons a single charge of therapeutic gas such as oxygen is usually enough for therapeutic purposes so long as the adhesive skin adhesion is leak-proof. I a preferred arrangement means are provided to purge the applied device of ambient air.

It is also an object of this invention to provide a hyperbaric chamber which can be readily self-applied in the home if appropriate. To this end it is, in practice, necessary to provide an economic system which is readily 94/2l323 I~CI`~ 94/0~542 - ~15893~

applied by those who are essentially unskilled. This requires both an economic, readily self-applied chamber ;and a source of pressurised therapeutic gas such as oxygen in a readily hand-portable form. In practice, once a topical hyperbaric device has been removed the adhesive properties thereof are usually too poor for the device to be reaffixed. Thus it is usual to replace it with a new device.
~ u9, t~e .ir)velltiol~ furtllel- o~ject ;rl t~le ~r~vlsioll lo of al) assemb.ly Or ~ topical llyp~rb~ric ~vi.c~ wit~ a llan~-por-table source o~ t)lerapeutic ~as sucll a~ oxygell, w~lic assem~Jy allow~ tlle topical llyperb~ric devi.ce to be char~ed Wit~l ~ des.ired pressilre (e.g. 1.~ atmos) witllout necessarily requ;ring the use of a pressure gauge. Of course, a pressure gauge call be a~plied ~o a hal~-portable gas cylillder and arrange~ suc~l tl~at 1.4 atmosplleres can be readily read Or~ from a desired value.

_ _ US-A-4224941 provides a topical hyperbaric device comprising a gas diffusion resistant flexible and/or resilient sheet material including an adhesive layer adapted to affix to the skin, said adhesive layer surrounding a treatment area, at least one release sheet disposed over the adhesive layer and a conduit for the supply of a therapeutic gas to the treatment area, the sheet material being formed of a generally planar sheet.

The present invention is characterized in that the adhesive layer is disposed upon the intended skin contact portion of the sheet, said release layer at least overlaying said adhesive face, and in that the hyperbaric device is adapted to retain a single charge of therapeutic gas over a treatment period.

The sheet material may be formed with a blister to ~v AMENDED SHE~T
IPEA/EP

Z15893~

accommodate a predetermined volume of therapeutic gas without stressing the interface in use between the skin and the adhesive layer.

5 Said US-A-42Z4941 provides the features given above, and additionally discloses that the sheet material is in the form of a inflatable bag, and that the adhesive layer is disposed about the peripheral underside portion at least of the portion of the bag adjacent the treatment area.
A second aspect of the invention is characterised in that said skin contact portion of the adhesive layer further, supports an external pressure ring about the treatment area adjacent the adhesive layer and independent of the sheet material, which ring allows pressure to be exerted towards the interface between the skin and the adhesive layer in use, and in that the hyperbaric device is adapted to retain a single charge of therapeutical gas over a treatment period.

In a third aspect of the invention there is provided an assembly of a topical hyperbaric device comprising a gas diffusion resistant flexible and/or resilient sheet material including an adhesive face adapted to affix the sheet material to the s~in, said adhesive face surrounding the treatment area, at least one release layer disposed over said adhesive face, a conduit for the supply of therapeutic gas to the treatment area, and a readily hand-portable canister of therapeutic gas for operative inter-connection with said conduit.
A final aspect of the present invention is characterised in that the release layer extends over a major proportion of the treatment area prior to use, and wherein the wound shape is sized- from the release layer or a gauging layer attached thereto prior to use, whereby the device adheres to the skin adjacent the wound so that the device adheres over as large an area of skin as possible.
AMENDED SHEET
IPEA/~P

2~8931~
- 6 ~

The sheet material may optionally be formed into a bag with an opening defined by the adhesive means in the form of a ring S for disposition about the treatment area. A moist dressing material may be disposed on a portion of AMENDED SHEE~T
IP~ P

W094/2~ ~ 16 8 9 3 ~ PCT/GB94/00542 the internal face of the bag which is opposed to the opening so that the dressing overlays the treatment area only in the substantial absence of hyperbaric pressure.

The adhesive means may be formed of a flexible/resilient sheet coated on both surfaces with an adhesive, for example a thin hydrocolloid having a thickness of 0.2 mm to 0.65 mm and preferably about 0.45 mm. The release sheet may be a silicone coated release paper for removal prior to adhesion to the skin.

In a preferred form of the invention the adhesive is double-sided and has the release sheet secured to one surface thereof. To the other surface is secured the inner edges of the flexible/resilient bag so as to secure a firm seal between the flexible/resilient material and the adhesive layer. Most preferably the bag is secured to the adhesive means adjacent the intended aperture to the treatment area, but is not secured over the whole outer area of the adhesive means. The adhesive means preferably extends therefore outwardly of its point of adherence with the bag, said adhesive means over this portion being covered by a second annulus so that the area around the aperture can be secured to the skin without direct contact therewith.

The present invention also seeks to improve upon prior art devices and to provide an economic alternative to the foregoing, by providing a topical hyperbaric device formed from a single operative sheet of flexible and/or resilient plastics material provided with adhesive to at least a - portion of one face thereof. Accordingly in this aspect, the hyperbaric device in accordance with the present invention has the general conformation of a traditional bandage or wound dressing but is provided with means for the supply of a therapeutic gas to a treatment area.

W094/2~ PCT/GB94/00542 215~93~ 8 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 which has hitherto not been generally available with the devices of the prior art.

The gas diffusion resistant flexible and/or resilient material is preferably a transparent plastics material such as polyalkylene or PVC sheet with an adhesive face over part or all thereof. Other materials utilised in the art for adhering bandages for wound dressings etc. are generally suitable for this. For example, they may comprise a thin hydrocolloid adhesive having a thickness of 0.20-0.60 mm (preferably 0.45 mm) backed by a 50 polyalkylene film, such as polyethylene.

The adhesive may extend over all of the operative face of the sheet material, in which case a dressing material may be adhered to the portion of the adhesive face which forms the intended treatment area. The dressing may be a traditional multi-layer woven material or a pharmacologically acceptable foam material for example.
Either may be impregnated with a pharmacologically active material, for example an antiseptic, an antibiotic, or an anti-inflammatory preparation, and/or may be absorbent.
The dressing may be moistened with sterile water or saline solution. Alternatively the dressing may be a medicated alginate dressing as known in the art. Very often the dressing is not necessary.

The release layer is an essentially non-adhesive layer which forms a weak bond with the adhesive disposed on the sheet material. 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 5kin about the wound. This arrangement allows the device to be 3~ 2 15 8 9~ 0 PCT/GB94/00542 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 rucks.

The flexible and/or resilient sheet material is preferably transparent and may be planar, or may be formed by non-elastic stretching or thermo-forming with a pocket over the treatment area to retain a dressing therein, or merely to provide a greater area for the containment of therapeutic gas. In such an arrangement where the dressing is not present, the adhesive does not extend over the treatment area.

The conduit for the supply of therapeutic gas is connected between the treatment area of the device and a canister of the therapeutic gas. It is sealed into the treatment area in a gas tight fashion, optionally by the use of an adhesive filler such as a clear silicone filler.

In a preferred form of the invention the conduit is comprised of a length of a flexible transparent pharmacologically acceptable plastics tubing, for example Trygon (Registered Trade Mark), R-3603. In such an arrangement an aperture is formed in the sheet 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 sheet material by means of a secondary layer of an adhesive sheet material disposed over the conduit and adjacent portions of the exterior face of the sheet material to secure the conduit. In order to ensure a fluid-tight seal it may be necessary to coat the exterior of the conduit with a secondary adhesive layer such as a silicone adhesive.

One of the reasons that hyperbaric therapeutic gas devices have been restricted in use is that the cylinders of WO 94/2L~23 PCT/GB94/005n 21~89~ 10 therapeutic gas tend to be heavy and require man-handling to the bedside. Alternatively sophisticated conduiting is re~uired in a hospital to deliver the therapeutic gas to the bedside. This has necessitated the utilisation of a hospital bed for hyperbaric treatment.

The devices of the present invention are suitable for use in out-patient departments because the applicants also provide a readily hand-portable therapeutic gas cylinder for utilisation with the hyperbaric device of the present invention.

The hyperbaric gas is usually oxygen, but may be other gases, for example an inert gas such as nitrogen, and may comprise other additives if therapeutically indicated.

The hand-portable canisters in accordance with the present invention may be a one-shot canister with an outlet adapted for interconnection with the conduit and means being provided to release pressurized therapeutic gas in the one-shot canister at least to the conduit. There is sufficient gas in the one-shot canistér to fill the treatment area once. The conduit may then be tied to prevent gas seepage, or the device may be provided with a one way valve or clamp to the same end.

Further, the canister or other device may be provided with means to supply the therapeutic gas to a treatment area at a predetermined pressure value, for example 1.03- 1.04 atmospheres. This may be effected by including a pressure responsive layer in the device which changes colour with changes in pressure.

In a preferred form of the invention the sheet material is provided with a closeable vent, the vent may comprise at least one aperture and preferably a plurality of small apertures formed, for example, by laser drilling, and WO94/213~ 21~ ~ 9 3 ~ PCT/GB94/00542 _ overlaid to the desired extend with a gas diffusion vent layer, whereby temporarily pealing back the vent layer allows gas to escape from the device.

This arrangement allows ambient air from the affixed device to be vented to the exterior prior to use and for limited purging of the device with the therapeutic gas before the gas pressure is increased to operational values. With the correct selection of adhesives for the vent layer it can be arranged that the vent layer will separate from the sheet material in use if the interior pressure of therapeutic gas exceeds a preset value. This provides a means for protection against inadvertent over-pressurisation and hence the formation of leakage path between the skin and the overlaying adhesive layer as will be formed by excessive internal pressures, may be avoided.

Alternatively the therapeutic gas canister may be of the multi-shot type, in which case a pressure actuated valve on said canister may be utilised to control the therapeutic gas supply and preferably its pressure via the conduit to the treatment area. Alternatively the vent arrangement alluded to above may be used. Again, means may be provided to prevent seepage cf the gas via the conduit in use when the canister is removed. This may, as previously stated, be effected by means of clamps, tying or by means of the use of one way valves within the device.

The devices according to the invention may be provided with a moisture indicator within the device; such a moisture indicator being secured within the device or attached to the dressing so that it changes colour as it dries. This enables the dressing, where used, to be replaced or re-moistened as necessary. The devices of this invention are useful in the treatment of conditions such as leg ulcers, wounds, post-operative WOg4/2~ PCT/GB94/00542 215~93 12 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 and scalds, necrotizingfaciitis, pyoderma gangreneosum, refractory ulcers and diabetic foot ulcers.

Of these pyodermic gangreneosum responds dramatically to hyperbaric therapy.

The devices according to the invention may be configured in any convenient size, for example from about 1 cm in diameter or diagonal, to body sized 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.

One aspect of the present invention is also directed to devices in accord with the present invention incorporating a secondary gas cushion. Such a gas cushion is adapted to protect the device when the same has been applied to an area such as an elbow, knee or heel against inadvertent knocks.

According, therefore, to a further feature of the invention there is provided a secondary gas diffusion resistant layer overlaying the primary gas diffusion resistant layer, said secondary layer being formed of a flexible and\or resilient sheet material secured about said primary layer by an adhesive facing, said secondary layer being provided with a secondary conduit for supply of a gas, optionally a therapeutic gas, after or simultaneously with, the supply of the therapeutic gas to the treatment area.

The device may comprise means, for example an LCD chip or a pressure-activated strip material which changes colour ~V094/21323 2 1 5 8 ~ 3 0 I'~I(,r`94/~0~42 -1~
or form on an illcrease in pressure; tl~ereby to iJl~icate a ~aximum fill con~ition, or to indicate t~at furtller therapeutic gas is re~uired.

The invention wil] now be describe~, by way of illustration only, witll reference to tlle accompanying drawings whereill:
Fiqure 1 shows a vertical cross-section througll a device of the invention from a first direction, Fiqure 2 sllows a vertical cross-section tllrougl~ a device of tlle illventior~ Lrom a second directioll, Fiqure 3 sllows a vertical cross-sectioll tllrough a device according to ~igure 1 i.n situ over ~ lesion, Fiqure 4 shows a vertical cross-section tllrougll a device in accordance wittl ~igures 1 and 2, b~lt incorporating a one-way valve, Fiqure 5 shows a diagrammatic side view from above oE a rectallgular device according to ~igure 1.
Fiqure 5~ shows a cross-section tl~rougt~ the vent yortior of Figure 5, Fiqure 6 shows a vertical cross-section througll anotller device according to the invention;
Fiqure 7 shows a vertical cross-section througl~ the devices o~ Figure 6 inflated over a lesion, and Fiqure ~ sl~ows a plan view from below o~ tlle device as shown in Figure 6 prior to removal of tlle release slleet.

With reference to Figures 1 to 5 of t~le accompanyillg drawings a topical hyperbaric device (1) is provide~ Wittl a flexible plastics transparent sheet material in tlle general form of a rectangle or square having a dimensio 3~ of 100 mm. 'I'lle slleet material (3) is formed over tl~e entirety of its lower surface wittl an ad~lesive layer (3A), whereas the upper layer is essentially non-ad~lesive.
Cenrally disposed Otl l;lle Utlder6~de C)~ tlle 611eet mateL ial (3) is an optional dressing (11) formed of a foamed material moistened by sterile water and\or Witll a AMEND D SHEE~T
IPEA/EP

~94t2132~ 2 1 5 8 9 3 JC~ 00542 p~)armacologica]ly acceptable alginate.

Io t)~e ullderside of t11e edges of t1~e 6~1eet materi.al (3) is applied ~ primary relea~e ~a~er (~) wl~ic1 is secure~ to the adhesive undersidé (3A) of the sheet material (3) and generally conform~ to t~le exterior ~erip~lery t~1ereo~.
11owever in tlle arra1lyeme1lt as s11ow1~ ln Figure I tlle edge portions of tlie primary release layer (~) do 1-ot adllere to t~le edge portiorls o~ t~le ulldersi~e Or tt1e .slleet material (3) but are left free. ~ secol~clary relea~e ]aye~ (l(l) is secure~l ~o eacl) ~ara]l.el edge of ~he ~l1eet ma~erial (3).

With reEerel)ce par~;cula~ly to ~igl1re ~ it wil.L ~e noted t~at t~1e dres~ir~g (l~) is pierce-l t~y ~l1e en~1 oE a col1duit (5) Wil;.C~I extellds ~etweel~ the valve (6) Or calli.ster (2) to the treatment area (16). Tile conduit (5) i.s ~ecured to tl1e exterior face o~ tlle slleet material (3) by mealls of an overla~ (7) preEerably formed of t~)e same material as tlle s~eet material (3) with an ad~lesive un~erside t~1ereon.

r~le overlay (7) secures tl1e condui.t (5) to tlle exterior face Or t~le sl1eet material (3) i11 a fluid tigllt ~as~1ion.
In order to reinEorce the fluid tigtlt efFect an ad~lesive silicone filler may be applied to tlle exterior of ~le conduit prior to adllesion of t11e overlay (7) to ensure tl)at tlle col)duit is truly secured an(l tilat no gas seepage can occur.

In an alternative form of the invention tl1e arrangeme1lt of Figure 2 is repeated but tlle dressing (ll) wl1eJl present is cut away over a portion so tl1at a one way valve (14) may be inserted to prevent seepage of tile oxygen in the reverse sense witllir) the conduit (5). The one way valve ~l4) may be a flexible sheet secured to tile under adllesive face oE the slleet material (3) but provi~ecl Witll an opening w11ich is securely closed by means of gaseous back pressure.

AMENDED SHEET
IP~ P

WO94/213~ 21~ ~ 9 3 U PCT/GB94/00542 ._ .

A general arrangement of the device is shown in Figure 5 which shows the device connected diagrammatically to a hand-portable therapeutic gas cylinder wherein the valve (6) has yet to be operated such that the hyperbaric device (1) lies flat upon a flat surface.

With reference particularly to Figure 3 the hyperbaric device in accordance with the present invention is shown in diagrammatic form in situ upon the skin. Initially hair is removed from about the wound site so that the adhesive face of the sheet material (3) can firmly adhere to the skin in a fluid-tight fashion. The device, as shown in Figure 1, is then presented to the wound (13) in the skin (12) and positioned generally thereover. It will be appreciated that, as shown in Figure 1, the transparent sheet (3) and the release layers (4, 10) result in an arrangement where it is not possible to be sure that the device is correctly orientated. For this reason a gap (15) is left in the device between the peripheral edge of the dressing (11) and the inner edge of the release layer (4).
Since this gap (15) is transparent it is possible to ensure that the device is correctly orientated. With the device held in position from one end, one of the release layers (10) may be removed and the edge of the release layer (4) folded back so that an adhesive edge of the sheet material (3) may then be correctly orientated upon the skin. When this has been pressed into firm adherence, the release layer (4) and the remaining release layer (10) are stripped away such that the sheet material (3) adhesively overlays undamaged skin without rucks, creases or gas releasing discontinuities.

With the device tl) located over the lesion (13) on the skin (12) the conduit (5) is connected to the valve (6) of the canister (2). The valve (6) is actuated to allow sterile oxygen to pass into the treatment space (16) whereby the dressing is raised from the lesion (13). With WO94/21323 2 i ~ ~ 9 3 ~ 94/00542 lG
a or1e-s11ot canis~er (2) t~lere is alw~ys t1~e pos~ibility t~lat ~)e oxyge~ providecl will exceed tlle volume of tlle treatment ~pace (16) w.ithout raisi1lg this are~ t~ too 11i.gl a pressure. For tll;.s reasorl ar1 operational vel1t: (P) may be ir1corporated as s11ow11 in Fi~ures 5 al1d 5~. Ver1t (8) comprises a plurality of laser drilled apert~1re~ (8~) throug11 the slleet material (3) a1ld an aclhes.ive resea].able ver1t layer (aB) w11ic11 can be ma1-ually li.fted ar~d replaced.
l`his allows tlle ~evice to be ~uryed of ambie1lt air after lo fi~.illq alld l~l-iol- to fi11~ r~ g ~ith ~xygell W11ere a o1-e-s1~ot cal1i~ter (2) ;~ uti.lised it m~r com~rise a valve w11ic11 is operated by ma11ual. pre~sure ~ 1 llellce it i.s possible to i11f1.ate tlle treatme11t ~pace (~ ) to tlle required degree al1d to top up as required for a sirlgle ~se o~ tlle device. ~ mult.i-s~1ot cal1i.ster car1 also br~ used for more t~1an devi.ce and is similarly c~esigned It is sometimes desirable that the dressing slloul~ be moist and s~1ould be provided Wit~1 suitable ~herapeutic adjuncts ~or t11e treatment of tlle lesion concerlled.
ZO ~lternatively, a desired level o~ moisture may be incorporated in tlle therapeutic gas.

Tl~e pressure ring is provided wit11 a generally central aperture and a plurality of concentric marki ngs to assist wound prori]ing. ln use tlle wound sllape is cut from tl1e çombined pressure ring and release layer, tl1e orientation o~ tlle device cllecked on the patient, al~d t~lell t~le release layer is removed and the adhesive race o~ tlle pressure ring adheres to the s~in as would tl1e adhesive layer in AMFNDE~ SHE~T
IP~ ~P

, g4/2132~ 2 1 ~ 8 ~ 3 0 I~{~ 94~00s42 -1.7 the earlier descri~ed embodiment.

'I'urnillg now to Figures 6 to 8 o~ t~le accompanyillg drawings, tilere is provided a secoll~ form of llyperbaric device provided optionally wit~ an illterllal dressillg. ~litl particular referellce to t~-e topical ~lyperbaric device (2~) there is provided a flexible P~C slleet l~avir~g a qenerally rectilinear col-~iguration as SI~OWIl i-l~ Figul-e ~. 'Ille ~'C
sheet is essentially ~lexible alt~ou~h it ~la~ a degree of resil;el~ce an~l ;r~ tllis case i~ a ~00 grade caclmium an~
lead-free di.-decyl pllt~lalate plasticized calelldered PVC of ~ type generally u~ed for uri~le bags. 'llle ~vC 6lleet (21) enclose~ a ilyper~ric ~pace (30) but is, in it~ pre-u~e conditiotl, qerler~lly flat a~d e-)c.lo~e~ witllill a sterile package.

Tl-e PVC sheet materi.al (21) may optionally be formed internally witll a generally square dressing (~7) whicll is of the alginate type and retains a desired amoullt of sterile water. The central lower portion of the sheet material (21) is formed with an aperture (31) which is opened on removal of the release layer (23). The lower ~aces of the PVC
sheet material are pressed into contact with a double-sided adhe~ive layer (22) to which they are firmly secured. The outboard edqes of the double-sided adhesive layer (22) are also covered with a release layer (23) so that the outer portions of the double-sided adhesive layer (22) do not adhere to the outer lower edges of the sheet material (21).
release sheet (23) overlays t~le double-sided adhesive layer, said release s1~eet being a silicone-coated release paper in accordance witl~ the knowll prior art. 'I`lle double-sided adhesive layer (22) has an adllesive of a tllickness of about 0.6 mm overlaying a central polyalkylene or PVC
film.

Wit~l particular reference to Figure 8, t~le release slleet AMENDED SHEE~T
IPEA/EP

-~94121323 Z1~ g9~ ~ rc r /c~ns4/nos~2 ln (23) w~iC~1 over.1.ay~ t~1e double-sided adl1esive 1ayer (22) is also provide~ Witl1 a target gri.d (33) printed t~lereuE~on .

Similar to t~1e arrar~gement as StlOW~ .igures ~ ~rd 4 Figures 5 and 6 are provided witl~ a conduit (~5) to admit hyperbaric oxygen. 6aid conduit is secured to tllo outer upper face o tl1e material (21) ~y means Or a ColldU.it overlay (26) careful]y secured as previously described before.

In use tl~e release layer (~3) wlli~ sllou]d be tr~n~arent and/or at 1.~a~t tt-~r~luce1lt is tem~?orarily wit1draw1~ from t~le devi~e (Z()) a11d p1ace~ over t11~ wo~11lc1 or l l~e le~ioll.
lhe release layer (23) is provi~e~ as S~10W11 i11 ~iyure 8 with a tar~et grid and from t1~is grid it ca-l bo readily seen w~lere tlle lesion is relative to the aperture (31).
parame~ic can ti~en draw an outli11e of t1~e wou~d 011 the release s~leet relating its centre to tlle centre of t~le grid (33) w~lereupo1l t~1e release s~1eet (23) is ot~ce more laid upon the double-sided release layer (22). ~i.t11 tl~is 2~ ligl1tly adllered t1~eret:o the paramedic may t1~en cut round the wound site so tl1at tl~e aperture formed in t~le device (20) corresponds to tl)e edges of tlle wound or lesion to w11ic11 it is to be applied. 111e remaining portions of t1~e release slleet are t11e1l removed and the device located over tl~e wound or lesion. 1`his is assisted because t~1e PVC
material (21) is transparent so tllat tlle wound can be accur~ately ~ligned wit}1 the aperture formed ror it.
External pressure portions (24) are then pressed firmly into contact with the skin (28) about the lesion so that the formed aperture (32) is retained about the wound.

11yperbaric oxygen is the1l introduced via conduit (25) from a-hand por~able oxygen cylinder ~2) 60 t~lat tll~ ~evice formed tlle shape somewhat as s1~own ill Figurè 6. Care must be taken not to overinflate tl1e device since tl1i6 may put AMENDED SHEE~T
IPEA/EP

~094/21323 2 1 ~ 8 9 ~ 9 ~ 94/00542 an undue strain 011 tl1e adl)esive bol-d between tlle ski~ 8) and tl1e device (2()). I{owever witll tlle l-al-d portable device it is possible to top up tlle hyperbari 5 ~ressure as necessary to a value usual~y Or about 1.03 to l.O4 atmosp1~eres.

Devices in accorclance wit11 tl~e present invel-ltioll may be applied sucl1 as to recluce hypoxia but`avoid oxygen toxaemia. Iypical regimens or 20 minutes twice a day, to ~
to 6 )lour treatments for ~ days o~ a week allow wounds and other lesions to cure quickly.

It will be ap~)rec;~ted tl~at ~ecall~e tlle tllera~eutic gas canisters are l~and-portable and because tlle devices in accorclance wit1~ tl~e present inverltioll are essentially disposable tlle assemblies in accordance witll tle present inventiorl may be utilised 011 an out-patient basis and even applied and utilised by motivated patients on some occasions wit1~out professiol~al medical intervention.
Accordingly tlle arrangements of tlle present invelltioll are cl1eap enougll and easy enougl- to use to bring l~yperbaric treatment more widely illtO use.

The invention provides, tllerefore a topical llyperbaric device and an assembly of a topica1 1~yyerbarlc clevice wit~
a readily 1~and-portable canister of tl~erapeutic gas suc1 as oxygen .

AMEND~D SHEET
IP!E~A/EP

Claims

CLAIMS:

1. A topical hyperbaric device (1.20) comprising a gas diffusion resistant flexible and/or resilient sheet material (3.31) including an adhesive layer (3A) adapted to affix to the skin (12) said adhesive layer (3A) surrounding a treatment area (16.30), at least one release layer (4.23) disposed over said adhesive layer and a conduit (5.25) for the supply of therapeutic gas to the treatment area; the sheet material being formed of a generally planar sheet;
characterised in that the adhesive layer is disposed upon the intended skin contact portion of the sheet, said release layer at least overlaying said adhesive layer, and in that the hyperbaric device is adapted to retain a single charge of therapeutic gas over a treatment period.

2. A device according to Claim 1 wherein the sheet material is formed with a blister to accommodate a predetermined volume of therapeutic gas without stressing the interface in use between the skin (12) and the adhesive layer.

3. A topical hyperbaric device comprising a gas diffusion resistant flexible and/or resilient sheet material (31) including an adhesive layer (3A.22) adapted to affix to the skin (12) said adhesive layer surrounding a treatment area (32), at last one release layer (23) disposed over said adhesive layer, and a conduit (25) for the supply of therapeutic gas to the treatment area; the sheet material being in the form of an inflatable bag (20) and the adhesive layer (3A.22) being disposed about the intended skin contact portion at least of the portion of the bag adjacent to the treatment area;
characterised in that said skin contact portion of the adhesive layer (22) further supports an external pressure ring (24) adjacent the treatment area and independent of the sheet material; which ring (24) allows pressure to be exerted toward the interface between the skin and the adhesive layer in use, and in that the hyperbaric device is adapted to retain a single charge of therapeutic gas over a treatment period.

4. A device according to claim 3 wherein the adhesive layer (22) is formed on a double-sided web, said release layer (23) adhering to a first side of the web, and said pressure ring (24) adhering to the second side.

5. A device according to any preceding Claim wherein the release layer (23) extends over a major proportion of the treatment area prior to use, and wherein a wound shape is excised from the release layer or a gauging layer attached thereto prior to use, whereby the device adheres to the skin (28) adjacent the wound without exposing more than a predetermined amount of undamaged skin to hyperbaric treatment.

6. A device according to any preceding Claim wherein the flexible and/or resilient material is a transparent plastics material, and the adhesive layer (22) is disposed over part or all thereof.

7. A device according to any preceding Claim wherein the adhesive layer is a hydrocolloid adhesive having a thickness of 0.2 to 0.6 mm backed by a 25µ to 75µ polyalkylene film.

8. A device according to Claims 1 or 2 wherein a dressing material (11) is disposed within the device and adapted in use to contact the treatment area (13), and wherein said adhesive layer extends over the whole operative face of the sheet material (3) in part to secure the dressing material to the adhesive layer thereon.

9. A device according to any preceding Claim wherein the release layer is a weakly adhesive layer forming a weak bond with the adhesive layer disposed in the sheet material.

10. A device according to any preceding Claim wherein the release layer (4.10) is formed of two or three layers in a partially overlapped configuration, whereby removal of one such layer (4) allows a portion of the adhesive face to be exposed for contact with the skin about the wound.

11. A device according to either of Claims 1 or 2 wherein the sheet material is transparent and either planar, or formed by non-elastic stretching or thermo-forming with a pocket over the intended treatment area.

12. A device according to any preceding Claim incorporating a secondary inflatable cushion adapted to protect the device when the same has been applied to an area likely to be subject to inadvertent pressures.

13. A device according to any preceding Claim further comprising a vent means (8) wherein at least one aperture (8A) is formed in the sheet material and wherein a resealable adhesive layer is applied thereover to reversibly obturate the said at least one aperture to allow purging of the in situ device.

14. An assembly of a device according to any preceding claim and a canister (2) for therapeutic gas therefor, wherein the conduit (5) for the supply of the therapeutic gas is connectable between the treatment area of the device and said canister.

15. An assembly according to Claim 13 wherein a remote end (6) of the conduit (5) is interlocked with a readily hand-portable canister of a therapeutic gas.

16. An assembly of a device with a pressurized canister of therapeutic gas according to any preceding Claim, wherein the therapeutic gas is medical grade oxygen.

17. A device or assembly according to Claim 15 wherein the canister or the hyperbaric device is provided with means for pressure controlled supply of gas to the treatment areas.