WO2007088348A2

WO2007088348A2 - Wound dressing

Info

Publication number: WO2007088348A2
Application number: PCT/GB2007/000317
Authority: WO
Inventors: Andrea Moretti; Richard Nagle
Original assignee: Wound Solutions Limited
Priority date: 2006-01-31
Filing date: 2007-01-31
Publication date: 2007-08-09
Also published as: GB0601928D0; WO2007088348A3; GB2434544A

Abstract

A wound dressing for covering a wound and an area of skin surrounding the wound comprising an electrically non-conductive base dressing and at least one electrode provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin wherein a cavity is provided in the base dressing to disperse pressure from the wound when pressure is applied to the wound dressing.

Description

Field of the Invention

The present invention generally relates to an apparatus and method for treating a wound. In particular, the invention relates to methods and apparatus for treating a wound by applying electrical signals to the skin of a human or animal.

Background of the invention

Chronic wounds such as diabetic foot or leg ulcers (DFU) which do not heal, represent a serious problem to sufferers and healthcare providers. The medical condition diabetes can cause damage to the nerve and vascular supply in the feet and legs. Such damage to the nerve supply or peripheral neuropathy leads to reduced or no sensation in the feet and lower legs. Consequently, sufferers may be unaware of injury caused to the feet by, for example ill-fitting footwear, an object in their shoes or walking on a piece of glass, stone or a drawing pin. Continued walking on the injured foot leads to further damage and minor lesions may develop into more serious wounds such as foot ulcers. Diabetic foot and leg ulcers occur at pressure points and are generally small but deep. Damage to the vascular supply or peripheral vascular disease results in the cut-off of the normal arterial supply by blockage of small vessels and delays healing of wounds or ulcers. Infection can then lead to the breakdown of tissue and spread to other parts of the foot or leg. Diabetic foot or leg ulcers are expensive to treat and in severe cases can lead to limb amputation. Early detection and appropriate treatment are very important in the management of the disease and can lead to the prevention of amputations.

Conventional treatment of diabetic foot or leg ulcers consists of dressing the wound with a suitable compound and then placing a dressing over the wound followed by the application of what is known as an "off-loading boot" or cast to reduce pressure applied to the wound. Sufferers are required to wear the off-loading boot when putting weight on the foot. Studies have shown that the process of healing, growth and regeneration in living tissue is brought about by the flow of endogenous electrical current. It has been suggested that the application of external microcurrents to injured tissue can assist the body's natural healing process by augmenting the flow of current through the injured tissue. The application of electrical signals to injured tissue as a form of therapy is known as electrotherapy and has been described in various publications.

Effective electrotherapy requires the use of suitable electrodes or pads for administering electrical signals to the skin. For treatment to be successful, electrodes must be effectively electrically coupled to the skin. Accomplishing such an effective coupling is not evident when applying electrodes to uneven skin surface and curved body parts. Any such electrode device must therefore be sufficiently flexible to accommodate the curvaceous nature of the human body and to accommodate relative movement of patients skin during therapy. Precise placement of electrodes on the body is another important requirement influencing the outcome of treatment.

Various electrodes for application of electrical signals to the skin have been proposed.

US5450845 describes a medical electrode system which includes a flexible electrically conductive patch disposed on an electrically non-conductive backing material. The basic electro-conducting and electrical distribution portion of the electrode is washable and reusable. A separate disposable, adhesive, electrical conductive pad is used to couple this portion to the skin. One embodiment of the invention described uses a plurality of electrodes and a system for insuring proper placement of the electrode set on the body part,

US6788979 describes an electrical stimulation compress kit which allows for precise repeatable positioning of stimulation pads onto a body part. The device includes a flexible member for contacting a body part and hook/loop members for tightly supporting the flexible member against the body part.

US 4982742 relates to a bandage capable of generating and applying microcurrent excursions across a soft tissue wound. The apparatus includes a bandage containing circuitry for generating the microcurrents, and a first and second electrode means coupled to the circuitry. A housing holds the first and second electrode means apart and adjacent to the selected area of tissue when the apparatus is placed over the selected area of tissue.

The above systems suffer from the disadvantages that they are not adapted to the treatment of diabetic foot or leg ulcers.

Summary of the invention

Accordingly, it is an object of the invention to provide a device which overcomes the drawbacks of the prior art.

The present invention provides a wound dressing for and a method of treating a wound.

One aspect of the invention provides a wound dressing for covering a wound and an area of skin surrounding the wound, comprising an electrically non-conductive base dressing, at least one electrode provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin, wherein a cavity is provided in the base dressing to disperse pressure from the wound when pressure is applied to the wound dressing.

Such an arrangement is extremely beneficial since the wound dressing protects the wound and off loads any pressure applied to the wound thereby helping the wound heal while the patient is receiving electrotherapy treatment through the electrodes. In an embodiment of the invention the electrode arrangement comprises an electrically non-conductive sealing arrangement for sealing the or each electrode to prevent ingress of moisture to the or each electrode.

The sealing arrangement prevents any blood, sweat, urine or exuded material from the wound reaching the electrodes and causing a short circuit between any electrodes placed around the wound. Such a short circuit would be very detrimental to treatment as it would deviate wound healing current away from the regenerative tissue under the wound.

Moreover, the waterproof sealing arrangement may also allow the patient to bathe or shower without having to remove the electrode dressing. This is especially advantageous for long term treatments where otherwise the wound dressing would have to be removed and disposed of and a new one applied each time the patient bathed or had a shower. Such an arrangement leads to both practical and economic benefits.

Another aspect of the invention provides a wound dressing for covering a wound and an area of skin surrounding the wound, comprising an electrically non-conductive base dressing, at least two electrodes provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin, at least two connectors connected to a respective electrode for providing electrical signals to the respective electrode, and an ion releasing compound for releasing ions into an area of treatment when electrical current is applied between the said at least two electrodes.

A further aspect of the invention provides a method of treating a wound comprising placing at least two electrodes in contact with the skin in a region peripheral to the wound, and and applying electrical current between electrodes of the at least two electrodes; wherein the electrodes are provided with a compound capable of releasing wound healing ions when an electrical current flows through said compound.

This method is particularly beneficial because, as the electrons pass from an anode to a cathode of an electrode pair, ions contained in the compound flow in a direction away from the anode and are deposited along the lines of current flow in the wound through a process known as iontophoresis. Depending on the ions used, the ions help fight against infection, and promote healing of the wound and stimulation of new tissue growth. The patient is therefore able to receive two types of treatment tailored to the treatment of wounds simultaneously.

Furthermore, by placing the electrodes on the undamaged skin on either side of the ulcer, current passing from one electrode to another will pass under the wound, through the regenerative tissue. Furthermore discomfort to the patient is minimised and since there is no direct contact between the electrode and the wound, the risk of infection is minimised while at the same time, application of the treatment to the patient by care providers is practical.

Another aspect of the invention provides an wound dressing for covering a wound and an area of skin surrounding the wound comprising an electrically non-conductive base dressing, at least one electrode provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin, at least one connector connected to a respective electrode for providing electrical signals to the respective electrode wherein the at least one connector is made from electrically conductive yarn.

Such an arrangement is extremely advantageous in the case of diabetic patients receiving electrotherapy. The skin of these patients is extremely fragile and vulnerable to the formation of wounds and ulcers when pressed against hard objects. Since the cable feeding signals to the electrodes must be rooted from an electrical generator to the foot and in many cases the patient may be wearing a conventional off-loading device such as a boot, the boot presses the cable against the skin of the leg of the cable. These may lead to the skin being broken and sores developing. The fabric cable helps to prevent this occurring since it does not result in localised pressure against the leg or foot of the patient.

In another embodiment of the invention the at least one electrode is made from electrically conductive fabric. The fabric electrodes placed on the delicate skin surrounding the ulcer during treatment help to prevent further damage to the skin.

In an embodiment of the invention at least two electrodes on the skin may be placed in the skin around an ulcer, an offloading device may be placed over the area of treatment, and electrical current maybe applied between electrodes of the at least two electrodes.

The method is particularly beneficial in that it allows two treatments tailored to the treatment of diabetic foot or leg ulcers to be carried out together. The patient therefore receives the beneficial effects of both treatments. In an embodiment of the invention, the method further includes the step of placing, in the region of the wound, a compound capable of releasing wound healing ions when an electrical current flows through said compound.

Beneficially the patient is then able to receive three types of treatment tailored to the treatment of diabetic foot or leg ulcers simultaneously.

In a further embodiment of the invention, the method of treating a diabetic foot or leg ulcer further includes placing, three or more electrodes on the skin around the wound.

This method is advantageous in that electrical current can be applied to take different paths through the regenerative tissue under the ulcer simultaneously or in sequence resulting in an increased efficiency of ulcer healing.

Any aspect of the invention can be used in conjunction with another aspect of the invention.

Brief Description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:-

Figure IA is a cross sectional view of a wound dressing according to a first embodiment of the invention;

Figure IB is a schematic diagram of a wound dressing according to the first embodiment of the invention;

Figure 2 is a cross sectional view of a wound dressing according to a second embodiment of the invention; Figure 3A is a cross sectional view of a wound dressing according to a third embodiment of the invention;

Figure 3B is a schematic diagram of a wound dressing according to the third embodiment of the invention;

Figure 4A is a Gross sectional view of a wound dressing according to a fourth embodiment of the invention;

Figure 4B is a cross sectional view of a wound dressing according to a further embodiment of the invention;

Figure 5 A is a schematic diagram of a wound dressing according to a fifth embodiment of the invention;

Figure 5B is a schematic diagram of a wound dressing according to a sixth embodiment of the invention;

Figure 6 is a schematic diagram of a wound dressing according to .a seventh embodiment of the invention;

Figure 7A is a schematic diagram of a wound dressing according to an eighth embodiment of the invention;

Figure 7B is a partial cross sectional diagram of one of the electrodes of Figure 7 A.

Figure 8 is a schematic diagram of an area of treatment showing the wound dressing of Figure 6 disposed in the area of a diabetic foot ulcer;

Figure 9A is a schematic diagram of a device for generating electrical current according to an embodiment of the invention; Figure 9B is a schematic diagram of a device for generating electrical current according to an alternative embodiment of the invention;

Figure 10 is a schematic diagram of an wound dressing according to an ninth embodiment of the invention; and

Figure 1 IA is a perspective view of an area of treatment illustrating a method of treating a diabetic foot ulcer according to an embodiment of the invention; and

Figure 1 IB is a perspective view of an area of treatment illustrating a method of treating a diabetic foot ulcer according to another embodiment of the invention.

Detailed description of the drawings

With reference to Figures IA and IB, a wound dressing according to a first embodiment of the invention comprises layer of gauze 20 having a first surface 21 and a second surface 22 opposed to the first surface, two electrodes 42 and 44 disposed on the first surface 21 of the gauze, for applying electrical signals to the skin 80 of a patient when placed on the skin and two electrical connectors 62 and 64 for supplying electrical signals to the electrodes 42 and 44, respectively, when connected to a suitable electrical generator. Electrically conductive gel layers 52 and 54 are provided on a surface of the electrodes 42 and 44, respectively, for releasably coupling the electrodes to the skin 80 of the patient while providing an electrically conductive path between the electrodes and the skin. A layer of electrically insulating, waterproof adhesive material 32a and 34a is disposed on the first surface of the gauze 20 to adhere the electrodes 42 and 44, respectively to the gauze 20 and to prevent the ingress of moisture from the gauze 20 to the electrodes. A strip of waterproof electrically non-conductive gel 32b, 34b is placed around the sides of the electrodes 42 and 44 preventing the ingress of moisture such as blood, sweat, urine or other matter exuded from the wound to the electrodes 42 and 44 and to the connectors 62 and 64 at the connections to the respective electrodes Adhesive gel 35 is disposed on the outermost edges of the first surface 21 of the gauze 20 for releasably adhering the wound dressing 10 to the skin 80. During use, the wound dressing 10 is positioned on the skin 80 in such a way that the electrodes 42 and 44 are positioned on the skin at each side of an ulcer 90 to be treated.

By placing the electrodes on the undamaged skin on either side of the ulcer, current passing from one electrode to another will pass under the wound, through the regenerative tissue helping it to grow and replace the damaged tissue. Furthermore since there is no direct contact between the electrode and the wound, discomfort to the patient is kept to a minimum, the risk of infection is minimised and application of the wound dressing to the patient by care providers is more practical.

The waterproof sealing arrangement around the electrodes prevents any exuded matter from the wound reaching the electrodes and creating a short circuit between the electrodes which would divert current away from the regenerative tissue under the wound. The sealing arrangement may also prevent external moisture from reaching the electrode and thereby allow the patient to bathe or shower without having to remove the electrode dressing. This is especially advantageous for long term treatments where otherwise the electrode dressing wound have to be removed and disposed of and a new one applied each time the patient bathed or had a shower.

In alternative embodiments, of the invention the layer of gauze may be covered by an external waterproof layer.

The electrodes 42 and 44 can be connected to an electrical generator circuit (not shown) via connectors 62 and 64, respectively. Electrical signals generated by the electrical generator pass through the connectors 62 and 64 to electrodes 42 and 44, respectively. From the electrodes 42 and 44 pressed against the skin of the patient, the electrical signals are administered to the skin of the patient around the wound. Such an arrangement promotes wound healing by passing electrical current between the electrodes through regenerative tissues under the wound.

The wound dressing 10 may be provided with a peel back protective layer which is provided on a first, surface of the dressing, covering the exposed surface of the electrodes and the sealing and adhesive gels. When the wound dressing is being prepared for use the peel back layer can be removed before placing the wound dressing over the region of the wound.

Figure 2 is a cross sectional view of a wound dressing 100 according to a second embodiment of the invention. The wound dressing comprises a foam pad 120 having a first surface 121 and a second surface 122 opposed to the first surface, two electrodes 142 and 144 disposed on the first surface 121 of the pad, for applying electrical signals to the skin of a patient when placed on the skin and two electrical connectors 162 and 164 for supplying electrical signals to the electrodes 142 and 144, respectively, when connected to a suitable electrical generator. Electrically conductive gel layers 152 and 154 are provided on a surface of the electrodes 142 and 144, respectively, for releasably coupling the electrodes to the skin 180 of the patient while providing an electrically conductive path between the electrodes and the skin. A layer of electrically insulating, waterproof adhesive material 132a and 134a is disposed on the first surface of the pad 120 to adhere the electrodes 142 and 144, respectively to the pad 120 and to prevent the ingress of moisture from the pad 120 to the electrodes. A strip of waterproof electrically non-conductive gel 132b, 134b is placed around the sides of the electrodes 142 and 144 preventing the ingress of moisture such as water, sweat, urine or blood to the electrodes 142 and 144 and the connectors 162 and 164 at the connections to the respective electrodes A strip of adhesive material 135 is disposed on the outermost edges of the first surface 121 of the pad 120 for releasably adhering the wound dressing 120 to the skin. A cavity 125 is provided in the foam pad and extends from the first surface 121 of the foam pad towards the second surface 122. The wound dressing 100 is positioned on the skin 180 in such a way that the electrodes 142 and 144 are positioned on the skin at each side of an ulcer 190 to be treated, and the cavity 125 is positioned over the ulcer.

The foam pad can protect the wound while the cavity in the pad can disperse any pressure applied externally to the pad away from the ulcer thereby helping the wound heal. Although in this embodiment adhesive electrically conductive gel is disposed on the electrode to increase conductivity between the electrodes and the sldn of the patient, in alternative embodiments of the invention a flexible adhesive strip of electrically conductive material may be applied to the electrodes to electrically couple the electrodes to the skin.

With reference to Figures 3A and 3B, a wound dressing according to a third embodiment of the invention comprises a waterproof pad 220 having a first surface 221 and a second surface 222 opposed to the first surface, a flexible substrate 210 disposed on the .first surface 221 of the waterproof pad 220, electrically non-conductive adhesive gel 230, two electrodes 242 and 244 disposed on a first surface 211 of the substrate, for applying electrical signals to the skin of a patient when placed on the skin, and electrically conductive gel layers 252 and 254 disposed on a surface of the electrodes 242 and 244, respectively, for releasably coupling the electrodes to the skin 280 of the patient while providing an electrically conductive path between the electrodes and the skin. An electrical cable 260 is provided for supplying electrical signals to the electrodes. The adhesive gel 230 is waterproof and is disposed around the edges of the first surface 221 of the pad 220 in the form of a strip and around the electrical cable releasably adhering the wound dressing to the skin and also preventing ingress of moisture to the electrodes 242 and 244 and to the connection between the cable and the electrodes 242 and 244. A strip of waterproof electrically non-conductive gel 232, 234 is disposed around the internal sides of each electrode 242 and 244, respectively, preventing the ingress of any matter exuded from the wound to the electrodes. During treatment of a patient with an ulcer or wound, the electrode dressing 200 is positioned on the skin 280 such that the electrodes 242 and 244 are positioned on the undamaged skin at each side of an ulcer 290 to be treated.

With reference to Figure 4A an wound dressing according to a fourth embodiment of the invention comprises a waterproof pad 320 having a first surface 321 and a second surface 322 opposed to the first surface, a flexible substrate 310 disposed on the first surface 321 of the pad 320, electrically non-conductive adhesive gel 330, two electrodes 342 and 344 disposed on a first surface 311 of the substrate 310 for applying electrical signals to the skin of a patient when placed on the skin, and electrically conductive gel layers 352 and 354 disposed on a surface of the electrodes 342 and 344, respectively, for releasably coupling the electrodes to the skin 380 of the patient while providing an electrically conductive path between the electrodes and the skin. One cable 360 is provided for supplying electrical signals to the electrodes. The electrically non- conductive adhesive gel 330 is waterproof and is disposed around the edges of the first surface 321 of the pad 320 in the form of a strip and around the cable 360 releasably adhering the dressing 300 to the skin and preventing ingress of moisture to the electrodes 342 and 344 and to the connection between the cable 360 and the electrodes 342 and 344. A strip of waterproof electrically non-conductive gel 332, 334 is disposed around the internal sides of each electrode 342 and 344, respectively, preventing the ingress of any matter exuded from the wound to the electrodes.

The gels 352 and 354 comprise silver chloride as an antibacterial wound healing agent. The presence of silver ions in the gel means that when electrical current is applied between the two electrodes 342 and 344, as the current passes from the anode to the cathode, silver ions flow from the anode and are deposited along the lines of current flow in the wound through a process known as iontophoresis. The silver ions help fight against infection, and promote healing, of the wound and stimulation of new tissue growth.

Although in this embodiment silver chloride acts as a healing agent, in further embodiments of the invention other silver compounds, zinc compounds and the like may be used to provide an iontophoresis effect. In even further embodiments the pad may be impregnated with iodine for healing purposes.

With reference to Figure 4B, a wound dressing according to a further embodiment of the invention comprises a waterproof pad 920 having a first surface 921 and a second surface 922 opposed to the first surface, a flexible substrate 910 disposed on the first surface 921 of the waterproof pad 920, electrically non-conductive adhesive gel 930, two electrodes 942 and 944 disposed on a first surface 911 of the substrate, for applying electrical signals to the skin of a patient when placed on the skin, and electrically conductive gel layers 952 and 954 disposed on a surface of the electrodes 942 and 944, respectively, for releasably coupling the electrodes to the skin 980 of the patient while providing an electrically conductive path between the electrodes and the skin. An electrical generator is 975 is provided on the second surface 912 of the substrate and is electrically connected to electrodes 942 and 944 to provide electrodes 942 and 944 with electrical signals. The generator is sealed against ingress of moisture by waterproof pad 920.

With reference to Figure 5A a wound dressing 400 according to a fifth embodiment of the invention includes a wound dressing similar to that of the first embodiment and further includes a layer of wound healing cream 450 disposed on the first surface 21 of the gauze 20 between the two electrodes. The wound healing cream helps to heal the wound in combination with electrotherapy treatment which can be provided through the electrodes.

With reference to Figure 5B, a wound dressing 800 according to a sixth embodiment of the invention includes a wound dressing similar to that of the first embodiment and further comprising an additional electrode 850 for positioning over the area of a diabetic foot ulcer 890. The additional electrode 850 is made of silver and placed over a gauze pad 851 soaked in an ionic silver solution which is placed over and in contact with the ulcer 890. Direct current in a range of 50-100 microamps is applied to the additional electrode and both of electrodes 842 and 844 are used as return electrodes. In this way current flows from the additional electrode 850 through the wound to electrodes 842 and 844 depositing silver ions in the ulcer by iontophoresis. The silver ions help fight against infection, and promote healing of the ulcer and stimulation of new tissue growth. The additional electrode 850 being made of silver can continue to provide silver ions to the gauze pad when the original silver ionic solution is depleted. The direct current may be applied to the additional electrode 850 for several hours a day between sessions of electrotherapy treatment carried out using electrodes 842 and 844.

It will be appreciated that in alternative embodiments a standard medical electrode may be used to deliver the silver ions to the treatment zone. In further embodiments the additional electrode may be provided with a layer of silver gel or a standard silver dressing known in the art. Alternatively a silver wire or mesh may be used as the electrode and the source of the silver ions. In further embodiments the electrode may be provided with a layer of zinc compound and arranged such that zinc is delivered to the periphery of the wound

It will be appreciated that any conventional medical wound dressing may be used as the base dressing of the wound dressing in the above described embodiments.

Although in the previous embodiments the wound dressing is provided with two electrodes, it will be appreciated that in alternative embodiments of the invention, the wound dressing can be provided with three or more electrodes. Furthermore, the electrode dressing may be provided with one electrode only.

With reference to Figure 6, a wound dressing 500 according to a seventh embodiment of the invention includes four electrodes 542, 544, 546 and 548 disposed on a first surface of a common annular shaped pad 520 and arranged around a central circular region 570. Each electrode is electrically isolated from another electrode. Connectors 562, 564, 566 and 568 provide electrical signals to the electrodes 542, 544, 546 and 548, respectively, when connected to an electrical generator. An annulus of waterproof electrically nonconducting gel 535 is disposed around the edges of the central circular region 570 on the first surface of the pad 520 and an annulus of waterproof non-conducting gel 530 is also disposed around the outermost edges of the pad to prevent the ingress of moisture to any exposed electrically conductive components of the electrical arrangement. The gels 530 and 535 contain adhesive material and adhere the wound dressing 500 to the skin. Electrically conductive gel (not shown) is applied to the exposed surface of the electrodes 542, 544, 546 and 548 to provide good electrical conductivity between the electrodes and the skin. The pad 520 is provided with a cavity located above the central region 570 to provide offloading of pressure from the ulcer.

During treatment the wound dressing in placed in the area of the ulcer such that the electrodes surround the ulcer and the central region 570 and off loading cavity is positioned over the ulcer. The size of electrode dressing and appropriate central region size can be selected according to the size of the ulcer being treated. This arrangement has the advantage that electrical current can be applied between different electrodes of the arrangement, thereby flowing through different current paths under the wound, sequentially or simultaneously. In addition since the electrodes are provided on a common pad, as well as being practical, the relative position between the electrodes will not change during treatment since the electrodes are fixed on the pad.

Although in this embodiment the dressing is provided with four electrodes, it may be appreciated that any number of electrodes may be provided on the surface to provide finer angular steps of electrodes around an ulcer and resulting in more complex current profile patterns across the area of treatment if required. Alternatively, the dressing may be provided with two electrodes.

Although in this embodiment electrically non-conductive sealing gel is placed around the edges of the aperture 570 and the outermost edges of the pad, in alternative embodiments the sealing gel may be placed around each electrode provided on the pad.

In alternative embodiments, perforations defining an annulus may be provided in the central region of the pad allowing a portion of the pad to be removed to form an aperture.

It will be appreciated that although the pad in this embodiment is annular shaped, in alternative embodiments the pad may have different shapes

With reference to Figure 7A, a wound dressing 600 according to a eighth embodiment of the invention includes six electrodes 642, 643 644, 645 646 and 648 disposed on a first surface of a common rectangular shaped pad 620 and arranged around a central region 670. Each electrode is electrically isolated from another electrode. Connectors 662, 663, 664, 665, 666 and 668 provide electrical signals to the electrodes 642, 643, 644, 645, 646 and 648, respectively, when connected to an electrical generator. A strip of electrically non-conducting gel 635 is disposed around the edges of the central region 670 and around the outermost edges of the pad, on the first surface of the pad 620, to prevent the ingress of moisture to any exposed electrically conductive components of the electrical arrangement. Figure 7B is a partial cross sectional diagram of one of the electrodes 644 of Figure 7A. The electrode 644 is provided on a first surface of the pad 620. A layer of ion releasing compound 694 is disposed on the surface of the electrode 644 and a layer of electrically conductive adhesive gel 654 for adhering the electrode 644 to the skin of the patient and providing an electrical conductive path from the electrode to the skin is disposed on the layer of ion releasing compound 694. A similar configuration of layers is used on all the electrodes of Figure 7A. When electrical current is applied between electrodes, electrical current passes through the layer of ion releasing compound and silver or other ions are released from the ion releasing compound and driven into the wound through an iontophoresis process.

Figure 8 is a schematic view of an area of treatment in which a wound dressing according to the seventh embodiment of the invention is placed over a diabetic foot ulcer located on the sole of a foot of a patient. The electrode dressing is positioned such that the electrodes surround the ulcer and the cavity is positioned over the ulcer. During treatment the exposed surfaces of the electrodes are arranged to face the skin of the patient. The outer edge of pad 520 provided with adhesive material 530 is pressed against the skin to seal the wound dressing to the skin and prevent the ingress of moisture to any exposed conductive components. Connectors 562, 564, 566 and 568 are connected between a single multiwire cable connected to an electrical generator circuit 2800 and electrodes 542, 544, 546 and 548 respectively. Electrical current can therefore be applied between different electrodes, thereby passing through different paths under the ulcer. For example, electrical current may be applied to pass from electrode 544 to electrode 548 and from electrode 542 to electrode 546. Furthermore, the direction of the current flow may be reversed so that current flows from electrode 548 to electrode 544, or from electrode 546 to electrode 542. The electrical current may be applied to pass between pairs of electrodes simultaneously or in sequence. In addition the electrical current may be applied to flow from one electrode to two or three other electrodes, simultaneously or sequentially. It will be appreciated that it is possible to apply the current to flow between many combinations of different electrodes. Current may be applied to flow between different electrodes simultaneously or in a sequence depending on the treatment required. Furthermore, the electrical generator 2000 may be programmed to provide a pre-deterrnined sequence of current profiles through different paths across the treatment area within the aperture of the electrode dressing.

A schematic diagram of an electrical generator circuit according to an embodiment of the invention is shown in Figure 9A. The electrical generator circuit 1000 comprises a battery 1002, a power control processor 1004, a voltage multiplier 1006, a programmable current source 1008, a waveform processor 1010, a polarity switch 1012, a user interface 1020, electrode ports 1014 and 1015. The device 1000 can be connected to electrodes of wound dressings through electrode ports 1014 and 1015.

Power control processor 1004 can activate the generation of current waveforms through user interface 1020 or automatically at predetermined times. Battery 1002 is a lithium coin cell type and runs the power control processor 1004 in low power mode. When current is required, power is supplied to the voltage multiplier 1006.

In this embodiment voltage multiplier 1006 is a dc-dc converter and multiplies the input voltage using a charge pump circuit. The charge pump circuit is power limited thereby providing a "fail-safe" operation. The voltage multiplier 1006 supplies a pumped voltage to the waveform processor 1010 and the programmable current source 1008.

Waveform processor 1010 controls the programmable current source 1008 and controls the polarity switch 1012. The programmable current source 1008 includes a feedback loop with the waveform processor 1010. Waveform processor 1010 monitors the output voltage between electrodes connected to electrode ports 1014 and 1015.

Programmable current source 1008 receives control signals from the waveform processor 1010 and converts them into an appropriate output current waveform.

Polarity switch 1012 receives a control signal from the waveform processor 1010 and a current signal from- programmable current source 1008. The polarity switch 1012 supplies the generated current waveform to electrode ports 1014 and 1015. In this embodiment polarity switch 1012 is a double pole change over switch utilising solid state analogue switches to switch polarity of the outputs. The direction of the current waveform applied between electrode ports 1014 and 1015 can thereby be switched.

The electrical generator circuit 1000 can be programmed to generate current waveforms with different parameters and can control the frequency and duration of application of current waveforms. This allows treatment of ulcers to be tailored to individual patients needs. Furthermore, the battery allows electrical signals to be generated for over 35 hours. The system is therefore suitable for long term treatments.

A further embodiment of a device for generating electrical waveforms is shown in Figure 9B. hi this embodiment the device 2000 comprises a polarity and connection sequence switch 2012, a waveform and sequence processor 2010, a voltage multiplier 2006, a programmable current source 2008, a power control processor 2004, a battery 2002 and a plurality of electrode ports 2014, 2015 2016 and 2017. The device 2000 can be connected to wound dressings through electrode ports 2014, 2015, 2016 and 2017.

Power control processor 2004 operates in a similar fashion to power control processor 1004 of the previous embodiment.

The waveform and sequence processor 2010 controls the programmable current source 2008 and the polarity and connection sequence switch 2012. Programmable current source 2008 receives control signals from the waveform processor 2010 and converts them into an appropriate output current waveform.

Polarity and connection switch 2012 receives a control signal from the waveform and sequence processor 2010 and a current waveform signal from programmable current source 2008. The polarity and connector switch supplies the current waveform to a pair of appropriate electrode ports 2014 and 2015, 2014 and 2016, 2014 and 2017, or 2015 and 2016 etc., based on the control signals received from the waveform and sequence processor 2010. The current waveforms may be applied between pairs of electrode ports simultaneously or sequentially. The current waveforms may also be applied to flow from two ports to one port or from one port to two ports simultaneously. The polarity and connection switch 2012 uses solid state analogue switches to switch the polarity of the current waveform and connect different combinations of electrode ports to the programmable current source. This arrangement allows the direction of the current to be switched and different combinations of electrode ports to be used.

Although in this embodiment the generator has only four electrode ports, any number of ports may be used.

With reference to Figure 10, a wound dressing 700 according to an ninth embodiment of the invention comprises two electrodes 742 and 744 formed from carbon fibre woven cable and provided on a soft fabric pad 720, and electrical leads 762 and 764 for supplying electrical signals to the electrodes 742 and 744, respectively, when connected to a suitable generator. The two electrode leads 762 and 764 are also made of carbon fibre woven cable. Electrically conductive gel is spread on the exposed surface of the electrodes 742 and 744 to electrically couple and releasably adhere the electrodes to the skin of a patient during treatment. Strips of electrically insulating gel 732 and 734 are placed around the electrodes 742 and 744 respectively to prevent the ingress of moisture to the electrodes and the connectors at the connection to the electrodes. The outer edges of the pad 720 contain adhesive material 730 for adhering the wound dressing to the skin.

It will be appreciated that the electrodes and the electrode leads may be made of any flexible conductor or yarn. For example the electrode lead may be made up of a conductive filament intertwined in soft material.

Such an arrangement is extremely advantageous for diabetic patients receiving electrotherapy. The skin of these patients is extremely fragile and vulnerable to the formation of wounds and ulcers when pressed against hard objects. Since the cable feeding signals to the electrodes must be rooted to the foot and in many cases the patient may be wearing a conventional off-loading boot, the boot presses the cable against the skin of the leg of the cable. These may lead to the skin being broken and sores developing. The fabric cable helps to prevent this occurring since it does not result in localised pressure against the leg of the patient. Similarly the fabric electrodes placed on the delicate skin surrounding the ulcer during treatment help to prevent further damage to the skin.

Accordingly, the method of the invention is particularly suited for use in conjunction with conventional methods of treatment of diabetic foot or leg ulcers. The electrode dressing is placed on the leg or the foot in the region of the diabetic ulcer with the electrodes arranged at each side of the ulcer. The leg is then fitted with an off-loading boot as shown in Figure 11a. Electrode leads 762 and 764 protrude from the off-loading boot for connection to an electrical generator. In this embodiment of the invention a conventional off-loading boot 780 is used. The off-loading boot off loads the pressure from the area of the ulcer helping it to help. Since the cables are made of soft fabric they do not press hard against the patients leg risking the formation of new ulcers and wounds. In addition, since the electrode cables protrude from the boot they are easily accessible for connection to the electrotherapy device and there is no need to remove and refit the boot before and after the electrotherapy treatment. Since there is no need to remove the off loading boot each time treatment is administered this is practical for both the patient receiving treatment and the carer administering the treatment. Furthermore, the electrotherapy treatment works in combination with the off loading treatment providing the benefits of the two treatments simultaneously.

In alternative embodiments the off-loading boot is provided with a pocket for holding the electrical generator providing the electrical signals to the electrodes. The pocket may be located on the exterior of the boot or inside the boot so that the wires do not need to protrude out from the boot as illustrated in Figure 1 Ib.

Alternatively the patient may be fitted with a moulded cast for off loading the pressure from the ulcer. In this case the electrode dressing is placed around the ulcer before the cast is applied. The cast is then applied as normal over the electrode system, with the electrical generator strapped to the outside of the cast and with connection to the electrode cables made after threading the electrode cable under or through the cast. In the above embodiment, the wound dressing 700 may be further provided with an ion releasing agent such as silver chloride which can release wound healing ions in the wound when electrical current is applied between the electrodes. Such an arrangement has the advantage that the patient can receive the beneficial effects of three types of wound healing treatment simultaneously.

Although the treatment of a diabetic foot or leg ulcer has been illustrated in the above example, it will be appreciated that the different types of wound dressing and methods may be applied to other types of wounds.

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular the different features from different embodiments maybe interchanged, where appropriate, and many other types of electrodes not specifically disclosed herein are also suitable.

Claims

CLAIMS:

1. A wound dressing for covering a wound and an area of skin surrounding the wound comprising : an electrically non-conductive base dressing; and at least one electrode provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin; wherein a cavity is provided in the base dressing to disperse pressure from the wound when pressure is applied to the wound dressing.

2. A wound dressing according to claim 1 further comprising an electrically non- conductive sealing arrangement for sealing the or each electrode to prevent ingress of moisture to the or each electrode.

3. A wound dressing according to claim 1 or 2, comprising at least two electrodes wherein the electrodes are arranged around the cavity.

4. A wound dressing according to any preceding claim, wherein the wound dressing is provided with a wound healing agent.

5. A wound dressing according to any preceding claim, wherein the sealing arrangement comprises adhesive material for adhering the wound dressing to the skin.

6. A wound dressing according to any preceding claim, wherein electrically conductive material is provided on a surface of the or each electrode to come into contact with the skin to provide an electrically conductive path to the skin.

7. A wound dressing according to claim 6, wherein the electrically conductive material comprises adhesive material for releasably adhering the or each electrode to the skin.

8. A wound dressing according to any preceding claim, wherein the wound dressing has a part annular shape.

9. A wound dressing according to any preceding claim, wherein the wound dressing has an annular shape.

10. A wound dressing according to any preceding claim, further comprising an electrical generator circuit on the second surface of the base dressing for applying current to at least one electrode.

11. A wound dressing according to claim 10, wherein the sealing arrangement is for preventing ingress of moisture to the electrical generator.

12. A wound dressing according to claim 10 or 11, comprising at least three electrodes, wherein the electrical generator circuit is adapted to switch current to flow between different electrodes of the at least three electrodes.

13. A wound dressing according to claim 12, wherein the electrical generator circuit is adapted to switch the direction of the current between electrodes.

14. A wound dressing according to any of claims 1 to 9 comprising at least one connector connected to a respective electrode for providing electrical signals to the respective electrode

15. A wound dressing according to claim 14 wherein the sealing arrangement is for preventing ingress of moisture to the or each connector at the connection to the respective electrode.

16. An apparatus for treating a wound comprising the wound dressing of claim 14 or 15 and an electrical generator circuit for applying current to at least one electrode via the respective at least one connector.

17. A method of using a wound dressing according to any preceding claim, wherein the wound dressing is arranged over the area of a wound such that the cavity is positioned over the wound and the said or each electrodes are arranged on the skin around the wound.

18. A wound dressing for covering a wound and an area of skin surrounding the wound comprising : an electrically non-conductive base dressing; at least two electrodes provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin ; at least two connectors connected to a respective electrode for providing electrical signals to the respective electrode ; and an ion releasing compound for releasing ions into an area of treatment when electrical current is applied between the said at least two electrodes.

19. A wound dressing according to claim 18, wherein electrically conductive material is provided on a surface of the at least two electrodes to come into contact with the skin to provide an electrically conductive path to the skin.

20. A wound dressing according to claim 19, wherein the said ion releasing compound is provided in the electrically conductive material.

21. A wound dressing according to any of claims 18 to 20, wherein the compound is a compound capable of releasing silver ions.

22. A wound dressing according to any of claims 18 to 21, further comprising an electrically non-conductive sealing arrangement for sealing at least one electrode to prevent ingress of moisture to the at least one electrode and to a respective connector at the connection to the respective electrode.

23. A wound dressing according to any of claims 18 to 22, wherein the wound dressing further comprises adhesive material for releasably adhering the wound dressing to the skin.

24. A wound dressing according to any of claims 18 to 23, wherein a cavity is provided in the base dressing to disperse pressure from the wound when pressure is applied to the wound dressing.

25. An apparatus for treating a wound comprising the wound dressing of claims 18 to 24 and an electrical generator circuit for applying current to at least one electrode via the respective at least one connector.

26. A wound dressing according to claim 25, comprising at least three electrodes and three connectors, wherein the electrical generator circuit is adapted to switch current to flow between different electrodes of the at least three electrodes.

27. A wound dressing according to claim 25 or 26, wherein the electrical generator circuit is adapted to switch the direction of the current between electrodes.

28. A wound dressing according to any of claims 18 to 27, wherein the wound dressing has a part annular shape.

29. A wound dressing according to any of claims 18 to 28, wherein the wound dressing has an annular shape.

30. A method of using a wound dressing according to any of claims 18 to 29, wherein the wound dressing is arranged over the area of a wound such that the wound is covered and the said or each electrodes are arranged on the skin around the wound.

31. A method of using a wound dressing according to any of claims 24 to 30 wherein the cavity is positioned over the wound.

32. A method of treating a wound comprising : placing at least two electrodes in contact with the skin in a region peripheral to the wound; and applying electrical current between electrodes of the at least two electrodes; wherein at least one of the electrodes are provided with a compound capable of releasing wound healing ions when an electrical current flows through said compound.

33. A method according to claim 32 wherein a wound dressing is placed over the wound.

34. A method according to claim 33, wherein the wound dressing is provided with a cavity and the cavity is placed over the wound to disperse pressure from the wound when pressure is applied to the wound dressing.

35. A method according to claim 32 or 33 wherein an off loading device is placed over the wound.

36. A method according to any of claims 32 to 35, further comprising switching the direction of the current flow between electrodes of the at least two electrodes to cause current to change direction across the wound.

37. A method according to any of claims 32 to 36, wherein at least three electrodes are placed in contact with skin in a region peripheral to the wound.

38. A method according to claim 37, wherein the current is switched at periodic intervals to flow between different electrodes of the at least three electrodes.

39. A method according to claim 37 or 38, wherein the current is switched to flow between different electrodes of the at least three electrodes in a pre-determined cycle.

40. A method according to claim 38 or 39, wherein the cycle is repeated.

41. A method- according to any one of claims 37 to 40, wherein a predetermined current waveform is applied across different electrodes of said at least three electrodes.

42. A method according to any of claims 32 to 41 wherein a further electrode provided with an ion releasing wound healing agent is placed over the wound and a direct electrical current is applied to the further electrode to flow from the further electrode to the one or more of the said or each electrodes

43. A wound dressing for covering a wound and an area of skin surrounding the wound comprising : an electrically non-conductive base dressing; at least one electrode provided on a first surface of the base dressing for applying electrical signals to the skin when placed on the skin; and at least one connector connected to a respective electrode for providing electrical signals to the respective electrode ; wherein the connector is made from electrically conductive yarn.

44. A wound dressing according to claim 43, wherein the connector is made from woven carbon fibre.

45. A wound dressing according to claim 43 or 44, wherein the at least one electrode is made from electrically conductive yarn.

46. A wound dressing according to any of claims 43 to 45, further comprising a compound for releasing ions into an area of treatment when electrical current is applied between the said at least two electrodes.

47. A wound dressing according to any of claims 43 to 46, wherein electrically conductive material is provided on the at least one electrode to provide an electrically conductive path to the skin.

48. A wound dressing according to any of claims 43 to 47 further comprising a compound for releasing ions into an area of treatment when electrical current is applied between the said at least two electrodes.

49. A wound dressing according to claim 48, wherein the said compound is provided in the electrically conductive material.

50. A wound dressing according to claim 48 or 49, wherein the compound is a compound capable of releasing silver ions.

51. A wound dressing according any of claims 43 to 50 , wherein the base dressing is provided with a cavity to disperse pressure from the wound when pressure is applied to the wound dressing.

52. A wound dressing according to any of claims 43 to 51, further comprising an electrically non-conductive sealing arrangement connected to the supporting pad for sealing at least one electrode to prevent ingress of moisture to at least one electrode and to at least one connector at the connection to the respective electrode.

53. A wound dressing according to claim 52, wherein the sealing arrangement comprises adhesive material for adhering the base dressing and the skin.

54. An apparatus for treating a wound comprising the wound dressing of any of claims 43 to 53 and an electrical generator circuit for applying current to at least one electrode via the respective at least one connector.

55. A wound dressing according to claim 54, comprising at least three electrodes and three connectors, wherein the electrical generator circuit is adapted to switch current to flow between different electrodes of the at least three electrodes.

56. A wound dressing according to claim 54 or 55, wherein the electrical generator circuit is adapted to switch the direction of the current between electrodes.

57. A wound dressing according to any of claims 43 to 56, wherein the base dressing has a part annular shape.

58. A wound dressing according to any of claims 43 to 57, wherein the base dressing has an annular shape.

59. A method of treating a wound comprising placing a first electrode provided with an ion releasing wound healing agent is placed over the wound; placing at least one further electrode on the skin around the wound; applying direct current to the first electrode such that ions are released by the first electrode and pass through the wound towards the second electrode.

60. A method of treating a wound according to claim 59 wherein the direct current in a range of from 50 to 100 microamperes.

61. A method of treating a wound according to claim 59 or 60 wherein a plurality of electrodes are placed on the skin around the wound such that current flows from the first electrode to the plurality of electrodes.

62. An electrode arrangement comprising a first electrode provided with an ion releasing wound healing agent for releasing ions when electrical current is applied; a second electrode for applying electrical signals to the skin of an animal the electrode arrangement being such that, in use, when the first electrode is placed on a wound, the second electrode is placed on the skin around the wound and direct current is applied to the first electrode, current flows from the first electrode to the second electrode depositing ions in the wound.