Title

Wound Treatment Apparatus

Field of the Invention The present invention relates to devices for wound treatment, in particular, devices employing negative pressure for treatment of wounds.

Background to the Invention

Healing of open wounds such as ulcers, pressure sores, infected wounds and burns can be troublesome and protracted, particularly where the wound is large or infected. In particular, in the case of decubitus ulcers or pressure sores, poor blood flow in the area of the wound can increase the healing time required. In many cases, this type of wound simply does not heal, resulting in a chronic ulcerated condition.

To stimulate fibroblastic proliferation, harmful fluids such as urine and exudates need to be removed from the wound bed. Once this is achieved, formation of granulation tissue may be encouraged by negative pressure as long as the tissue is supported. Negative pressure is thought to increase blood flow in and around the wound, thereby promoting healing, and may also pull the edges of the wound together, thereby encouraging formation of granulation tissue. Open cell foam may be used in conjunction with negative pressure to provide both tissue support, to prevent distention and promote healing, and porosity, which is vital for achieving fluid drainage away from the wound.

One device for applying this type of pressure to a wound has been proposed in European Patent No. 0 620 720. This patent describes an apparatus comprising vacuum means for applying a negative pressure between about 1.01 and 100.3 kPa to an area of skin including and surrounding the wound. The apparatus also comprises a seal which contacts the skin surrounding the wound to maintain the negative pressure, and an open- cell polymer foam screen within the seal. The open cell foam is for preventing overgrowth of tissue at the wound.

Another such device is described in European Patent No. 0 688 189. This patent describes an appliance for administering a reduced pressure treatment to a wound. The

appliance comprises an impermeable flexible sheet for covering and enclosing the wound and for maintaining reduced pressure at the site of the wound. The appliance also comprises a vacuum system and a vacuum pump for producing a reduced pressure. The vacuum system includes a filter for preventing the pump from venting micro - organisms aspirated from the wound.

It is desirable to provide an improved wound treatment device for applying a reduced or negative pressure to a wound. Irrigation is a method of wound cleaning, in which wound debris is mechanically removed from the wound site by pressurised fluid. The removal of this debris facilitates wound healing. Furthermore, wound irrigation ensures that the wound site is moist, thereby encouraging growth of tissue.

Summary of the Invention

The present invention relates to a wound treatment device, comprising irrigation means for application of an irrigation fluid to the wound and suction means for removal of the irrigation fluid from the wound area.

An advantage of the present invention is that the wound is kept moist and free of debris by means of irrigation, thereby promoting healing of the wound. Optimum moisture levels at the wound site may be achieved by irrigating and draining the wound alternately or simultaneously, such that fresh irrigation fluid is continually supplied to the wound and then removed by suction. Furthermore, exudate produced by the wound is also removed by the suction means. A further advantage is that the suction means has the effect of applying negative pressure to the wound, thereby increasing blood flow at the wound site and further promoting healing of the wound.

The irrigation means may include pressure means, and a cannula in fluid communication with the pressure means, wherein one end of the cannula is for positioning at the wound, and wherein the pressure means is operable to deliver pressurised irrigation fluid to the wound through the cannula.

The pressure means may comprise a syringe. The syringe may be a powered syringe. Alternatively, the pressure means may comprise a pump to pressurise the irrigation fluid.

The irrigation fluid may be applied to the wound at high pressure, for example, between about 55 kPa and about 83 kPa. Alternatively, the irrigation fluid may be applied to the wound at low pressure, for example, below about 55 kPa.

The irrigation means may comprise means for metering the irrigation fluid. This ensures that an optimum level of irrigation is achieved. The irrigation fluid may be applied to the wound drop by drop. Suitably, the irrigation fluid is a saline solution. Alternatively, the irrigation fluid may comprise liquid nitric oxide.

The suction means may comprise a vacuum means for application of a partial vacuum to the wound. The partial vacuum applied to the wound may be approximately 750 Pa. The partial vacuum provided by the suction means draws the irrigation fluid away from the wound. The suction means may be arranged to apply an intermittent vacuum or suction to the wound. Optimum results may be achieved when suction is applied to the wound at 4.5 minute intervals.

The suction means may further comprise conduit means and a drainage container to collect irrigation fluid drawn from the wound area. The suction means may be arranged to apply suction to the drainage container. The suction applied to the drainage container may be transmitted through the conduit means to the suction head, to apply suction to the wound.

The suction means may comprise a suction head releasably positionable at the wound. The suction head may be shaped to enclose the wound such that suction is maintained on the wound area. A sealing engagement between the suction head and the skin surrounding the wound also helps to retain the suction head in position on the wound area.

In one embodiment, the suction head comprises a porous member on a skin-engaging surface thereof. The porous member may be between about 0.5 cm and about 1 cm thick. Preferably, the porous member comprises an absorbent open-cell porous tissue. Advantageously, the porous member comprises open-cell polymer foam.

The porous member serves a number of purposes in the device. First, it absorbs excess irrigation fluid from the wound and wicks it away from the wound site. The porous nature of the member allows fluid to pass through it under the suction provided. Additionally, the porous member serves to support the tissue at the wound and the surrounding area and prevents overgrowth of tissue at the wound.

Brief Description of the Drawings

Figure 1 is a schematic representation of a wound treatment device according to an embodiment of the present invention; and Figure 2 is a cross sectional view of the suction head of the wound treatment device of Figure 1.

Detailed Description of the Drawings

With reference to Figures 1 and 2, there is illustrated a wound treatment device 1, shown in use on a wound 2. The device comprises a main body portion 18 and a suction head 12. The device includes irrigation means 3 for application of an irrigation fluid to the wound. The device also comprises suction means 4 for removal of the irrigation fluid from the wound area.

The irrigation means comprises a pump 5, a metering device 8 and a cannula 6. The cannula is in fluid communication with the pump 5 and the metering device 8. As shown in the drawing, one end 7 of the cannula is for positioning at the wound 2. The pump 5 is operable to deliver pressurised irrigation fluid to the wound 2 through the cannula 6. The amount of fluid applied to the wound is metered by the metering device 8. The device may be arranged to ensure that an optimum level of irrigation is achieved. For example, the metering device 8 may be set to apply the irrigation fluid to the wound drop by drop. Alternatively, the metering device may be arranged to apply

the irrigation fluid to the wound continuously. In another embodiment, the metering device may be arranged to deliver the fluid to the wound in intermittent bursts.

The suction means 4 comprises a suction head 12 releasably positionable at the wound. The suction head 12 is shaped to enclose the wound 2 such that suction is maintained on the wound area. The suction head 12 comprises an absorbent open-cell porous tissue 13, for example of open-cell polymer foam, on a skin-engaging surface thereof.

The suction means 4 further comprises a length of flexible tubing 14 and a drainage container 15 to collect irrigation fluid drawn from the wound area. One end 16 of the flexible tubing 14 is arranged within the suction head 12 adjacent the wound. The other end 17 is in fluid communication with the drainage container 15.

The suction means 4 further comprises a mains operated suction pump 9 for application of a partial vacuum of about 750 Pa to the wound and a filter 10 to prevent microorganisms drawn from the wound being released into the surrounding atmosphere. The device also includes control electronics 11 to control operation of the device 1. The pump 9 is arranged to apply a partial vacuum to the drainage container 15.

In use, the suction head 12 is arranged in tissue supporting contact with the wound area such that the absorbent tissue 13 is interposed between the innermost contact surface of the suction head 12 and the wound site 2. The suction head is held in place by virtue of its shape and the partial vacuum applied to its internal surface. The end 7 of the cannula 6 is arranged within the absorbent tissue 13 such that irrigation fluid is dispensed within the suction head, through the foam onto the wound site.

The suction means is operable to create a partial vacuum within the drainage container 15. The suction applied to the container 15 is transmitted through the tubing 14 to the suction head 12, thereby drawing the dispensed irrigation fluid away from the wound site. The rate of delivery of the irrigation fluid and the vacuum applied are selected to ensure that the wound is maintained in a moist condition for optimum healing. The fluid removed from the wound passes through the flexible tubing 14 and is retained in

the drainage container 15. The drainage container may be emptied at regular intervals, for example, by the patient or by nursing staff.

The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.