TECHNICAL FIELD

The invention relates to an electrode arrangement for an antiseptic dielectric barrier discharge plasma treatment of a wound area on a skin surface, comprising a planar electrode and a dielectric embodied as a planar material, wherein the planar electrode is fastened to the dielectric in such a way that a layer of the dielectric shields the electrode from the skin surface.

BACKGROUND

It is known that the skin of the human or animal body can be treated by cold plasma in order to generate different effects. A substantial effect lies in the antiseptic effect of the ionized gas that forms the plasma. The antiseptic effect can, in particular, promote wound healing since the wound healing can be impeded by germs, in particular streptococci. Moreover, it appears to be possible to treat skin infections using a plasma (Heinlin et al.: “Plasmamedizin: Anwendungsmoglichkeiten in der Dermatologie” [Plasma medicine: Application options in dermatology] in JDDG 12-2010 (volume 8) pages 968-977).

Very different arrangements have been disclosed for generating plasma for treating the skin surface.

A commonly applied embodiment provides for the generation of a so-called plasma jet, in which the plasma is generated within a rod-shaped housing. The housing forms an applicator tip, from which the ionized gas emerges as a plasma beam and is projected onto the skin. The instrument can be held and guided like a ballpoint pen in order to successively expose the skin surface to be treated to the ion beam which tends to be incident in a punctiform manner.

Moreover, DE 10 2007 030 915 A1 has disclosed the practice of forming hollow fibers from a dielectric substance, which hollow fibers are provided in the interior thereof with a metallically conducting coating such that the hollow fiber forms a dielectric with an internal shielded electrode which, together with the surface of a conducting body, for example the skin surface, serving as a counter electrode, may form a plasma field. Here, provision is also made for forming a web using the hollow fibers which can be placed in a planar manner on an irregular surface, in particular the skin surface of the human body. The advantage of an electrode arrangement that can be adapted to the irregular topology of the skin surface for performing a plasma treatment is generated hereby.

WO 2011/076193 A1 has furthermore disclosed a flexible planar electrode arrangement of the type set forth at the outset. Here, the dielectric is formed by a flexible planar material which shields a planar flexible electrode from the surface to be treated when the dielectric lies on the surface to be treated. On the side pointing toward the surface to be treated, the dielectric is provided with a structure for forming air guiding regions in which the plasma is generated during the treatment, i.e. directly on the skin surface. In the process, the planar electrode can be embedded in the dielectric and only protrudes from the dielectric with an electrical high-voltage connector. Shielding in relation to the skin surface is realized by this embedding. Therefore, the embedding can be substantially on one side, but also on all sides.

For the purposes of fastening exoprostheses, i.e. prostheses which replace an amputated body part, it is conventional to form a prosthesis shank which engages over the remaining amputation stump of the amputated body part and which is fastened there, for example with the aid of negative pressure. This type of fastening of prostheses leads to problems if there is a change in the soft tissue structure in the amputation stump. Therefore, the process of performing an osseointegration, i.e. of fastening the exoprosthesis to the bone of the amputation stump, has been proposed. To this end, an adapter, on which the prosthesis can be fastened, must be introduced through the skin into the bone and fastened there. Since the adapter is to be implanted for an unlimited time and must protrude through the skin to the outside, it is important that no germs enter into the interior of the body through the separation point between adapter and skin or soft tissue. Therefore, the assumption is made that the adapter should have a surface which hinders the settlement of germs thereon and for example consists of polished titanium. In the process, it is necessary to disinfect the employed adapter and the region of the skin around the adapter regularly in order thus to prevent the emergence of infections by germs.

For the purposes of stabilizing the adapter in the soft tissue, the practice of inserting the adapter into the amputation stump in such a way that a planar soft tissue anchor surrounds the adapter and forms a large porous perforated surface, through which soft tissue can penetrate, such that the adapter comprising the soft tissue anchor thereof grows into the soft tissue has furthermore been proposed.

Tests have also already been carried out as to whether the growing-in of the adapter, possibly with a soft tissue anchor, can be accelerated and improved using a bioactive coating, for example with hydroxylapatite. In the long-term, such a coating may be helpful, but it does not prevent the problems resulting from possible infections.

Similar problems also exist in the case of other transcutaneous devices, such as e.g. permanent catheters, permanent infusion cannulas etc.

SUMMARY

The present invention is therefore based on the object of simplifying the use of transcutaneous devices in order to highlight an option for simple and permanent disinfection of the skin and tissue region surrounding the transcutaneous device fastened to the body.

According to the invention, this object is achieved by an electrode arrangement of the type set forth at the outset by virtue of the electrode arrangement including a ring-shaped contact surface that is formed by the dielectric and being provided for fastening to a skin penetration piece bringing about skin penetration with a longitudinal axis such that the electrode arrangement surrounds the skin penetration piece and the contact surface is at an angle >20° in relation to the longitudinal axis.

Here, the dielectric can be provided on the side thereof facing the skin surface with a structure for forming air guiding regions when the dielectric lies on the skin surface by way of the structure. Here, the structure is preferably formed by protruding lugs or studs, the surfaces of which form the contact surface.

The dielectric—and hence the planar electrode—may consist of a rigid dielectric material, for example a ceramic. However, for the purposes of contacting the skin surface, it may be advantageous to embody the planar electrode in a flexible manner by virtue of both the electrode itself and the dielectric consisting of a flexible material. The dielectric is preferably a flexible polymer or elastomer.

In order to achieve the stated object, a device of the type set forth at the outside is further, according to the invention, characterized in that a ring-shaped, planar electrode arrangement including a contact surface that is at an angle to the longitudinal axis is fastenable to the skin penetration piece, which electrode arrangement includes the planar electrode and a planar dielectric shielding the planar electrode from the skin surface and is embodied for generating a dielectric barrier discharge plasma between the dielectric and the skin surface as counter electrode.

Therefore, by using the present invention, it is possible to combine a plasma electrode with the transcutaneous adapter in order thereby to be able to generate a suitable plasma field by means of which the skin penetration region and the surroundings thereof on the skin surface can be disinfected in a reliable manner. Here, it is also possible to prevent the emergence of a damaging biofilm on the adapter, even in the skin penetration region. As a result, it is possible to dispense with the previous, possibly damaging use of chemicals, the addition of silver ions, etc. After insertion of the adapter, the plasma electrode device also brings about improved wound healing for the operation wound. The exudate usually emerging after the insertion of the adapter is both reduced and made germ-free by the plasma treatment, and so improved wound healing is made possible by a regular plasma treatment. Here, the electrode arrangement can be permanently connected to the adapter or, in a preferred embodiment, be connectable to the adapter in an easily detachable manner in order thus to be able to be placed onto the adapter for the plasma treatment.

The electrode arrangement surrounds the adapter in a ring-shaped manner. Here, the ring shape need not extend through 360°, but can extend over a partial circle, for example a three-quarter circle or a semicircle in order to simplify the subsequent attachment. The ring-shaped preferably extends over a circumferential angle between π and 2π.

The device according to the invention, which includes an adapter for fastening an exoprosthesis, may include all features which were previously found to be expedient for such devices and which have been explained above, for example a polished surface which hinders germs settling thereon, a surface formed with a bioactive coating, a soft tissue anchor, which can likewise be provided with a bioactive coating, etc.

The device according to the invention can also be one of the aforementioned other transcutaneous devices and, by means of the plasma electrode, prevent the ingress of external germs into the body interior or accelerate wound healing. Accordingly, the electrode arrangement according to the invention may also be used in conjunction with transcutaneous cannulas and external fixators. The device for establishing a transcutaneous connection can therefore also comprise a cannula or an external fixator.

An electric control of the electrode arrangement according to the invention or of the device according to the invention can be attached directly on the electrode arrangement. However, it is also possible to provide the control device on e.g. the exoprosthesis itself and, for example, connect said control device to the electrode arrangement by means of plug-in connection when the electrode arrangement is required, by way of example is plugged onto the adapter for use. Here, the mechanical connection between the electrode arrangement and the adapter can be brought about by means of a suitable fastening device. It is particularly advantageous for the electric device to have a flexible embodiment and for the adapter to be provided with a pressure element for pressing the flexible electrode device in the direction of the proximal end of the adapter such that the contact surface of the electric device is pressed against the skin surface. The electrode control can also be embodied in such a way that it brings about a gas supply to the skin surface such that the plasma is primarily not formed by the surrounding air but by the supplied gas. In this manner, the plasma treatment can be accompanied by a supporting therapeutic treatment by means of the supplied gas.

Furthermore, it is possible to embody the plasma as low-pressure plasma if a negative pressure space is formed with the skin surface by means of a bell arrangement. The dielectric barrier discharge plasma is then generable in the negative pressure space under negative pressure. To this end, the bell arrangement can consist of a molded plastic, which is so stable that it maintains the bell shape, even in the case of applied negative pressure. The free edge of the bell arrangement may be sealed with respect to the skin surface by means of a sealing ring.

In a particularly preferred arrangement, the bell arrangement is formed by the dielectric on which the electrode is fastened. The electrode is preferably embedded into the dielectric. Here, the dielectric forming the bell arrangement both has the function of providing the dielectric barrier for the plasma discharge and of forming the negative pressure space with the skin surface.

