Negative pressure device

1. An apparatus for providing negative pressure at a wound site, comprising:

a first negative pressure reservoir comprising a supply of negative pressure at a first negative pressure level;

a conduit in communication with the first negative pressure reservoir and configured to supply the negative pressure in the first negative pressure reservoir to a wound chamber at a wound site;

a first reservoir valve in communication with the conduit and the first negative pressure reservoir, the first reservoir valve configured to regulate and maintain a level of the negative pressure in the wound chamber by:

opening to allow the negative pressure stored at least in the first negative pressure reservoir to be supplied to the wound chamber in response to the pressure in the wound chamber increasing, and

closing in response to the pressure in the wound chamber reaching a desired negative pressure;

wherein the first reservoir valve is configured to open and close in response to a pressure difference between pressure in the wound chamber and pressure in at least the first negative pressure reservoir;

a second negative pressure reservoir in fluid communication with the first negative pressure reservoir; and

a second reservoir valve in fluid communication with the first and second negative pressure reservoirs, the second reservoir valve being configured to control delivery of the negative pressure supplied by the second negative pressure reservoir to the first negative pressure reservoir.

2. The apparatus as claimed in claim 1 , further comprising:

a third negative pressure reservoir in fluid communication with at least one of the first and second negative pressure reservoirs; and

a third reservoir valve in communication with the third negative pressure reservoir and at least one of the first and second negative pressure reservoirs, the third reservoir valve being configured to regulate a level of the negative pressure supplied by the third negative pressure reservoir to at least one of the first and second negative pressure reservoirs.

3. The apparatus as claimed in claim 1 , wherein said first negative pressure reservoir comprises a rigid housing and wherein an internal surface of the housing provides a chamber region.

4. The apparatus as claimed in claim 1 , wherein said first negative pressure reservoir comprises a flexible body containing a porous elastic filler.

5. The apparatus as claimed in claim 4 , wherein the filler comprises a plurality of polystyrene beads.

6. The apparatus as claimed in claim 1 , wherein the first and second negative pressure reservoirs comprise a rigid housing, an internal surface of the housing providing a chamber region.

7. The apparatus as claimed in claim 1 , wherein the second negative pressure reservoir comprises a flexible body containing a porous elastic filler.

8. The apparatus as claimed in claim 7 , wherein the filler comprises a plurality of polystyrene beads.

9. The apparatus as claimed in claim 1 , further comprising a wound filler material configured to be disposed in a cavity region below a sealing drape configured to be disposed over the wound site.

10. The apparatus as claimed in claim 4 , wherein the filler disposed within the first negative pressure reservoir is configured to expand so as to increase the volume in the reservoir when a level of negative pressure in the first negative pressure reservoir diminishes.

11. The apparatus as claimed in claim 1 , further comprising a control valve configured to selectively connect the first negative pressure reservoir to an additional source of negative pressure to increase a level of negative pressure in the first negative pressure reservoir.

12. The apparatus as claimed in claim 1 , further comprising one or more additional negative pressure reservoirs and a control valve configured to selectively connect each of one or more additional negative pressure reservoirs to an additional source of negative pressure.

13. The apparatus as claimed in claim 1 , wherein a pressure in the wound chamber is configured to be maintained at less than 200 mm Hg below atmospheric pressure.

14. The apparatus as claimed in claim 1 , wherein a pressure in the wound chamber is configured to be maintained at less than 125 mm Hg below atmospheric pressure.

15. The apparatus as claimed in claim 1 wherein a pressure in the first negative pressure reservoir is configured to be maintained at greater than 500 mm Hg below atmospheric pressure.

16. The apparatus as claimed in claim 1 , wherein a level of negative pressure in the second negative pressure reservoir is greater than a level of negative pressure in the first negative pressure reservoir.

17. The apparatus as claimed in claim 1 , wherein a volume of the first negative pressure reservoir is greater than a volume of the wound chamber.

18. The apparatus as claimed in claim 17 , wherein the volume of the first negative pressure reservoir is more than three times greater than a volume of the wound chamber.

19. The apparatus as claimed in claim 1 , further comprising:

a porous elastic filler positioned within the first negative pressure reservoir, the porous elastic filler comprising a plurality of beads configured to expand so as to increase the volume in the reservoir when a level of negative pressure in the first negative pressure reservoir diminishes; and

wherein the first negative pressure reservoir is flexible.

20. The apparatus as claimed in claim 19 , wherein the porous elastic filler comprises a plurality of polystyrene beads.

21. A method of providing negative pressure at a wound site, comprising selectively connecting a first negative pressure reservoir to a wound chamber at a wound site via a first reservoir valve to maintain a level of negative pressure in the wound chamber by:

opening the first reservoir valve to allow negative pressure stored at least in the first negative pressure reservoir to be supplied to the wound chamber in response to the pressure in the wound chamber increasing;

closing the first reservoir valve in response to the pressure in the wound chamber reaching a desired negative pressure, wherein the first reservoir valve is configured to open and close in response to a pressure difference between pressure in the wound chamber and pressure in at least the first negative pressure reservoir; and

selectively connecting a second negative pressure reservoir to the first negative pressure reservoir via a second reservoir valve to control delivery of negative pressure from the second negative pressure reservoir to the first negative pressure reservoir.

22. The method as claimed in claim 21 , further comprising selectively connecting a third negative pressure reservoir to at least one of the first and second negative pressure reservoirs via a third pressure reservoir valve.