Wound dressings

1. A dressing for covering a wound of a patient, comprising:

a sheet member adapted to be adhered to the patient's skin in use to provide an airtight seal around the wound, wherein the sheet member is adapted to be spaced apart from the skin in the region of the wound to define in use a space above the wound, and

a plurality of mutually spaced-apart flutter valves permitting one-way air, blood and/or other fluid flow communication from the space above the wound to the exterior of the dressing,

wherein the sheet member is a multilayer sheet member comprising a first layer nearest the patient's skin in use and at least one additional layer overlying at least a portion of the first layer on the major face thereof directed away from the patient's skin in use, and

wherein the first layer is skin-adhesive on the major face that is directed towards the patient's skin in use, and an aperture is provided in the first layer, so that the first layer can surround the wound, but not adhere to it, when the first layer is positioned on the patient's skin to surround the wound and adheres to the patient's skin around the wound to provide an airtight seal to the skin around the wound.

2. The dressing according to claim 1 , wherein the dressing, including the flutter valves, is formed from one or more sheet materials which are of sufficient flexibility that the whole dressing is skin-conformable and the sheet material has substantially no rigid parts.

3. The dressing according to claim 1 , wherein the at least one additional layer comprises a film layer which overlies the wound encircling aperture above the major face of the first layer of the sheet member that is directed away from the skin in use, and extends radially outwardly to overlie a portion of the first layer of the sheet member around the aperture,

wherein the film layer is sealed to the first layer of the sheet member and is provided with a plurality of holes defining the mouths of the plurality of flutter valves of the dressing, and

wherein the flutter valves permit one-way air, blood and/or other fluid flow communication from the space above the wound to the exterior of the dressing.

4. The dressing according to claim 1 , wherein the dressing has two or three flutter valves.

5. The dressing according to claim 1 , wherein the dressing has four flutter valves.

6. The dressing according to claim 1 , wherein the dressing has five flutter valves.

7. The dressing according to claim 1 , wherein the sheet member includes skin-adhesive coating comprising one or more gels, hydrocolloids, pressure-sensitive adhesives or any combination thereof.

8. The dressing according to claim 7 , wherein the skin-adhesive coating comprises a hydrogel.

9. The dressing according to claim 8 , wherein the hydrogel comprises a hydrated polymer formed by polymerisation of one or more monomers selected from olefinically unsaturated aliphatic or aromatic vinyl sulphonic acids, vinyl sulphobetaines, acrylic and methacrylic sulphonic acid esters, 2-hydroxy-3-acryloxy propyl sulphonic acid, 2-hydroxy-3-methacryloxy propyl sulphonic acid and 2-acrylamido-2-methyl-propanesulphonic acid and salts thereof.

10. A dressing for covering a wound of a patient, comprising:

a sheet member adapted to be adhered to the patient's skin in use to provide an airtight seal around the wound, wherein the sheet member is adapted to be spaced apart from the skin in the region of the wound to define in use a space above the wound,

a plurality of mutually spaced-apart flutter valves permitting one-way air, blood and/or other fluid flow communication from the space above the wound to the exterior of the dressing, and

a spacer device which comprises:

one or more outwardly extending projections which in use extend in the region of the flutter valves of the dressing and serve to space external objects away from the dressing to prevent the flutter valves from being pressed closed by the external objects, and

apertures being present through the projection(s) and/or between projections so that air, blood and other fluid can pass from a space above the flutter valves to the external atmosphere when the spacer is in place on the dressing, when an external object is laid over the dressing and spacer.

11. A dressing for covering a wound of a patient, comprising:

a sheet member adapted to be adhered to the patient's skin in use to provide an airtight seal around the wound,

one or more mutually spaced-apart flutter valves permitting one-way air, blood and/or other fluid flow communication from a space above the wound to the exterior of the dressing,

wherein the dressing has a threshold valve-opening overpressure of less than about 2.2 cm H 2 O, and

a spacer device which comprises:

one or more outwardly extending projections which in use extend in the region of the flutter valves of the dressing and serve to space external objects away from the dressing to prevent the flutter valves from being pressed closed by the external objects, and

apertures being present through the projection(s) and/or between projections so that air, blood and other fluid can pass from a space above the flutter valves to the external atmosphere when the spacer is in place on the dressing, when an external object is laid over the dressing and spacer.

12. The dressing according to claim 11 , wherein the dressing has two, three, four or five valves.

13. The dressing according to claim 11 , wherein the sheet member includes skin-adhesive coating comprising a hydrated polymer formed by polymerisation of one or more monomer selected from olefinically unsaturated aliphatic or aromatic vinyl sulphonic acids, vinyl sulphobetaines, acrylic and methacrylic sulphonic acid esters, 2-hydroxy-3-acryloxy propyl sulphonic acid, 2-hydroxy-3-methacryloxy propyl sulphonic acid, 2-acrylamido-2-methyl-propanesulphonic acid and salts thereof.

14. A dressing for covering a wound of a patient suffering from a penetrating chest wound, comprising:

a sheet member adapted to be adhered to the patient's skin in use to provide an airtight seal around a space defined by the dressing over the wound,

at least one mutually spaced-apart flutter valve permitting one-way air, blood and/or other fluid flow communication from the space above the wound to the exterior of the dressing,

wherein the sheet member is adapted to be adhered to the patient's skin in use by being provided with a skin-adhesive coating comprising a hydrated polymer formed by polymerisation of one or more monomer selected from olefinically unsaturated aliphatic or aromatic vinyl sulphonic acids, vinyl sulphobetaines, acrylic and methacrylic sulphonic acid esters, 2-hydroxy-3-acryloxy propyl sulphonic acid, 2-hydroxy-3-methacryloxy propyl sulphonic acid, 2-acrylamido-2-methyl-propanesulphonic acid and salts thereof, and

a spacer device which comprises:

one or more outwardly extending projections which in use extend in the region of the flutter valves of the dressing and serve to space external objects away from the dressing to prevent the flutter valves from being pressed closed by the external objects, and

apertures being present through the projection(s) and/or between projections so that air, blood and other fluid can pass from a space above the flutter valves to the external atmosphere when the spacer is in place on the dressing, when an external object is laid over the dressing and spacer.

15. The dressing according to claim 14 , wherein the dressing has two, three, four or five valves.