IMPROVEMENTS RELATING TO APPARATUS NEGATIVE PRESSURE WOUND THERAPY

Abstract

An apparatus (1) for negative pressure wound therapy comprises a source of reduced pressure (10) and first (22a) and second (26a) chambers, the first chamber being in fluid communication with the source of reduced pressure such that a negative pressure may be generated in the first chamber, the negative pressure being prevented from exceeding a predetermined value by way of a pressure release means (30), and the second chamber comprising means (28) for establishing a fluid connection with a wound. A valve (24) between the first and second chambers permits the negative pressure in the second chamber to increase in response to an increase in the negative pressure in the first chamber and prevents the negative pressure in the second chamber from dropping in response to a drop in the negative pressure in the first chamber.

Claims

1. An apparatus for negative pressure wound therapy comprising: a source of reduced pressure; a first chamber in fluid communication with the source of reduced pressure such that the source of reduced pressure is operable to generate a negative pressure in the first chamber; a pressure release means that prevents the negative pressure in the first chamber from exceeding a predetermined negative pressure value; a second chamber comprising means for establishing fluid communication between the second chamber and a wound; a valve located between the first chamber and the second chamber, the valve permitting the negative pressure in the second chamber to increase in response to an increase in the negative pressure in the first chamber, and preventing the negative pressure in the second chamber from dropping in response to a drop in the negative pressure in the first chamber.

2. The apparatus of claim 1, wherein the predetermined negative pressure value is 120 mmHg or higher.

3. The apparatus of claim 1 further comprising a means for detecting the negative pressure that is applied to the wound.

4. The apparatus of claim 3, wherein the means for detecting the negative pressure that is applied to the wound is in fluid communication with the second chamber.

5. The apparatus of claim 3, wherein the means for detecting the negative pressure that is applied to the wound is operably coupled to the source of reduced pressure such that the source of reduced pressure is deactivated in response to the negative pressure that is applied to the wound reaching a desired level and/or the source of reduced pressure is activated in response to the negative pressure that is applied to the wound dropping below a desired level.

6. The apparatus of claim 5, wherein the desired level of negative pressure that is applied to the wound is between 75 and 125 mmHg, 80 and 120 mmHg, 90 and 110 mmHg, or about 100 mmHg.

7. The apparatus of claim 3, wherein the means for detecting the negative pressure that is applied to the wound is an electronic pressure sensor such as a piezoresistive electronic pressure sensor.

8. The apparatus of claim 1, wherein the source of reduced pressure is a vacuum pump.

9. The apparatus of claim 1, wherein the source of reduced pressure has a maximum dimension of less than 100 mm, less than 80 mm, less than 60 mm or less than 40 mm.

10. The apparatus of claim 1, wherein the source of reduced pressure occupies a volume of less than 10 cm.sup.3, less than 8 cm.sup.4, less than 6 cm.sup.3 or less than 4 cm.sup.3.

11. The apparatus of claim 1, wherein the maximum power consumption of the source of reduced pressure is less than 5 W, less than 3 W or less than 2 W.

12. The apparatus of claim 1, wherein the first and second chambers are defined by housings.

13. The apparatus of claim 12, wherein the housing of the first chamber and the housing of the second chamber are structurally the same.

14. The apparatus of claim 12, wherein the housings comprise a relatively soft material in at least the regions in which they engage the other components of the apparatus.

15. The apparatus of claim 14, wherein the relatively soft material is a thermoplastic elastomer such as thermoplastic polyurethane or styrene-butadiene rubber.

16. The apparatus of claim 1, wherein the volume of each of the first chamber and the second chamber is less than 5 cm.sup.3, less than 3 cm.sup.3, or less than 1 cm.sup.3.

17. The apparatus of claim 1, wherein the valve located between the first chamber and the second chamber is a one-way valve.

18. The apparatus of claim 17, wherein the valve located between the first chamber and the second chamber is a diaphragm valve.

19. The apparatus of claim 1, wherein the pressure release means operates by permitting the entry of gas into the first chamber.

20. The apparatus of claim 19, wherein the pressure release means communicates between the first chamber and a source of gas.

21. The apparatus of claim 19, wherein the pressure release means is a flow restrictor.

22. The apparatus of claim 21, wherein the pressure release means is a precision orifice.

23. The apparatus of claim 1, wherein the means for establishing fluid communication between the second chamber and a wound comprises a Luer lock or another conventional medical connector.

24. A system for negative pressure wound therapy comprising: an apparatus for negative pressure wound therapy according to claim 1; and, a wound dressing for negative pressure wound therapy in fluid communication with the second chamber of the apparatus.

25. A kit for negative pressure wound therapy comprising: an apparatus for negative pressure wound therapy according to claim 1; and, a plurality of wound dressings for negative pressure wound therapy adapted for the establishment of fluid communication with the second chamber of the apparatus.

26. A method of negative pressure wound therapy comprising: applying a wound dressing for negative pressure wound therapy to a wound; establishing fluid communication between the wound dressing and the second chamber of the apparatus according to claim 1; and, activating the apparatus.

27. The system of claim 24, wherein the wound dressing comprises a wound contact layer of soft silicone gel.

28. The system of claim 27, wherein the layer of soft silicone gel includes gaps or perforations.

29. The system of claim 24, wherein the wound dressing comprises a superabsorbent material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The invention will now be described in greater detail, by way of illustration only, with reference to the accompany drawings, in which

[0046] FIG. 1 is a perspective view of an exemplary embodiment of an apparatus for negative pressure wound therapy according to this invention.

[0047] FIG. 2 is an exploded perspective view of the apparatus for negative pressure wound therapy of FIG. 1.

[0048] FIG. 3 is an additional exploded perspective view of the apparatus for negative pressure wound therapy of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0049] FIGS. 1 to 3 depict an exemplary embodiment of an apparatus for negative pressure wound therapy according to this invention, which is generally designated 1. The apparatus 1 comprises a source of reduced pressure in the form of a vacuum pump 10, a connector assembly 20, and a printed circuit board (PCB) 40. The PCB 40 comprises a pair of projections 42 to which the vacuum pump 10 is soldered in order to secure the vacuum pump 10 to the PCB 40. The connector assembly 20 engages with the vacuum pump 10 via a vacuum port 12 located on the vacuum pump 10.

[0050] The connector assembly 20 comprises a first tubular connector 22, a one-way valve 24, a second tubular connector 26 and a port 28. The first tubular connector 22 comprises a housing that defines a first chamber 22a, and which is formed of a primary tube 22b having an opening at each end that communicates between the first chamber 22a and the exterior of the connector 22, and a side tube 22c that branches from the primary tube 22b and has an opening at its free end that communicates between the first chamber 22a and the exterior of the connector 22. The second tubular connector 26 is of identical construction to the first tubular connector 22 and comprises a housing that defines a second chamber 26a, and which is formed of a primary tube 26b and a side tube 26c.

[0051] The first tubular connector 22 engages with the vacuum port 12 via the opening at the end of its primary tube 22b that is proximal to the vacuum pump 10, and engages with the one-way valve 24 via the opening at the end of its primary tube 22b that is distal to the vacuum pump 10. The second tubular connector 26 engages with the one-way valve 24 via the opening at the end of its primary tube 26b that is proximal to the vacuum pump 10, and engages with the port 28 via the opening at the end of its primary 26b tube that is distal to the vacuum pump 10.

[0052] The one-way valve 24 is and permits the passage of gas from the second chamber 26a into the first chamber 22a, but prevents the passage of gas from the first chamber 22a into the second chamber 26a, The port 28 is a conventional Luer lock that is capable of forming a substantially air-tight connection with a medical tube for establishing fluid communication with a wound site.

[0053] The first tubular connector 22 further comprises a pressure release valve 30 in the form of a precision orifice that is located in the opening in the free end of its side tube 22c. The pressure release valve 30 permits the entry of gas into the first chamber 22a from the surroundings in order to prevent the level by which the pressure in the first chamber 22a is reduced relative to the pressure in the surroundings (ie the “negative pressure” in the first chamber 22a) from exceeding a predetermined negative pressure value of 120 mmHg.

[0054] The second tubular connector 26 further engages with a pressure sensor 32 via the opening in the free end of its side tube 26c. The pressure sensor 32 is embedded in the PCB 40 and detects the level by which the pressure in the second chamber 26a is reduced relative to the pressure in the surroundings (ie the “negative pressure” in the second chamber 26a). The pressure sensor 32 is operably coupled to the vacuum pump 10 via the PCB 40 such that the vacuum pump 10 is deactivated when the negative pressure in the second chamber 26a reaches the desired negative pressure value.

[0055] The apparatus 1 further comprises an integral power source (not shown) for the vacuum pump 10 in the form of a battery pack and is contained within in a housing (not shown).

[0056] The tubular connectors 22,26 are formed from injection moulded thermoplastic elastomer, which is relatively soft compared with the material of the components with which they engage, namely the vacuum port 12, one-way valve 24, the port 28, the pressure release valve 30 and the pressure sensor 32. Accordingly, the tubular connectors 22,26 deform slightly in the regions that engage with the other components, ensuring good surface contact and hence a substantially air-tight connection between the components without the need for precision assembly.

[0057] In use, an occlusive dressing is applied over a wound that is to be treated. The occlusive dressing is traversed by a tube that is attached to the port 28 using a standard luer lock mechanism in order to form a substantially air-tight connection between the apparatus 1 and the wound. The vacuum pump 10 is then activated, which extracts gas from the first chamber 22a via the vacuum port 12 and the opening at the end of its primary tube 22b that is proximal to the vacuum pump 10, thus generating a negative pressure in the first chamber 22a. The pressure release valve 30 permits the entry of gas into the first chamber 22a from the surroundings, and thus prevents the negative pressure in the first chamber 22a from exceeding 120 mmHg, which is generally regarded to be the maximum negative pressure that can be safely applied to a wound.

[0058] The generation of a negative pressure in the first chamber 22a creates a pressure differential between the first chamber 22a and the second chamber 26a, resulting in the passage of gas through the one-way valve 24 from the second chamber 26a into the first chamber 22a and hence the generation of a negative pressure in the second chamber 26a. As the pressure release valve 30 prevents the negative pressure in the first chamber 22a from exceeding 120 mmHg, the negative pressure in the second chamber 26a also cannot exceed 120 mmHg. The pressure sensor 32 detects the negative pressure in the second chamber 26a and deactivates the vacuum pump 10 when the negative pressure in the second chamber 26a reaches a predetermined value. The negative pressure in the second chamber 26a at which the vacuum pump 10 is deactivated may be set electronically and may range from 80-120 mmHg.

[0059] Following deactivation of the vacuum pump 10, the negative pressure in the first chamber 22a may drop as a result of the entry of gas into the first chamber 22a through the pressure release valve 30 or the body of the vacuum pump 10. The one-way valve 24 prevents the passage of gas from the first chamber 22a into the second chamber 26a, and hence prevents the negative pressure in second chamber 26a from dropping in response to any drop in the negative pressure in the first chamber 22a.

[0060] As the second chamber 26a is in direct fluid communication with the wound via the port 28, the negative pressure in the second chamber 26a is the same as that applied to the wound. Accordingly, the negative pressure in the second chamber 26a may fluctuate due to movement of the patient or direct pressure applied to the wound, and in particular may drop as a result of the occlusive dressing not forming a complete seal around the wound.

[0061] The pressure sensor 32 detects the negative pressure in the second chamber 26a and causes activation of the vacuum pump 10 when the negative pressure in the second chamber 26a drops below a predetermined value. The negative pressure in the second chamber 26a at which the vacuum pump 10 is activated may be set electronically and may range from 80-120 mmHg and must be lower than the negative pressure at which the vacuum pump 10 is deactivated. The vacuum pump 10 continues to operate until the negative pressure in the second chamber 26a reaches the predetermined value at which the vacuum pump 10 is deactivated. The apparatus thus maintains the negative pressure that is applied to a wound at a substantially constant level for as long as is required.