1. Field of the Invention
The invention concerns a process and a bandage for treatment of wounds.
2. Description of the Related Art
For treatment of wound infections and wounds which contain dead tissue, for example, for treatment of the diabetic gangrene, fly larvae are employed, in particular larvae of the fly genus Lucilia (bluebottle flies) and in particular Lucilia scricata. The fly larvae (maggots) are employed for a specific amount of time, for example three days, in the wound in need of therapy. It has been shown that the maggots in this time remove necrotic tissue in the wound (biodebridement), eliminate bacterial infections and stimulate healing of the wound.
In the method for treatment with surgical maggots employed until now, after cleansing of the wound the edge or rim of the wound is first covered with an adhesive strip. The maggots are applied to a fine mesh net, which is then inverted and adhered to the adhesive strips, such that the maggots are situated between the net and the wound surface. The net serves as an air-permeable cage, which restrains the maggots in the wound. After the effective time of approximately three days, the net is pulled off and the maggots are removed from the wound.
In this method, various problems can occur. The adhesive bond between the net and the wound edge is not absolutely reliable. If the adhesive edge comes loose, it is not possible to prevent escape of maggots, which can then pupate so that bottle flies develop. The removal of the maggots from the wound after conclusion of the treatment is time-consuming and, in particular for the patients, is not aesthetic. Further, in larger wounds it cannot be guaranteed that the maggots are active in particular there where the strongest therapeutic effect is to be targeted.
The present invention is concerned with a task of providing a process and a bandage for treatment of wounds, which overcome or reduce the above-mentioned disadvantages associated with the known treatment with surgical maggots.
The invention is based upon the recognition that the therapeutic effect of the maggots on the wound is in particular attributable to the secretions secreted by the maggots. These secretions, in particular the digestive secretions, liquefy necrotic tissue so that it can be taken up by the maggots as nutrient. The secreted fluid has a strongly anti-bacterial effect and promotes wound healing.
The fundamental concept of the invention is based on the idea that the maggots are not to be freely released into the wound, but rather a wound overlay or applique is to be to employed, which contains the secretion of fly larvae important for the therapeutic effect. The wound overlay can be strategically placed there where the secretion is desired to have a therapeutic effect. In this manner it can be ensured that even in larger wounds the entire wound surface can come in contact with the secretion in an even manner. Likewise, specific areas of the wound can be targeted for treatment with a higher dose and concentration of the secretion.
The wound overlay can be applied with good contact with the wound surface. For this, one can also employ in certain cases a core or insert, which urges the wound overlay to lie against the wound surface. The good surface contact between the wound overlay and the wound surface ensures that the secretion is effective in the entire area of the wound surface. The wound overlay can, after conclusion of the active period, be removed from the wound in a simple and problem-free manner without leaving residues.
In a preferred embodiment, a pouch of a fine-mesh net-like material, preferably a textile material, containing fly larvae is included in the wound overlay. One or more pouches, which contain the maggots, are introduced into the wound. The maggots contained in the pouch have no chance of escape or to migrate to other wound areas. Thereby, it is not only ensured that the maggots do not escape from the wound, but rather it is in particular also insured, that the maggots exercise their therapeutic effect in that wound area where the pouch is applied. In this way it is possible to produce a targeted enhanced or strengthened therapeutic effect in certain wound areas. Likewise, it can be ensured, by the application of multiple small-area pouches, or by the application of one large surface area pouch which is sub-divided into smaller enclosed chambers, that the maggots were distributed evenly over the entire wound surface and that they do not collect in an undesired manner in certain wound areas, in which for example the therapeutic effect is less necessary. Finally, by the enclosure of the maggots in a pouch, a rapid, simple and reliable removal of the maggots from the wound is possible. Since the patient does not see the maggots contained in the pouch, the aesthetic and psychological problems of treatment with surgical maggots is substantially reduced.
The material, of which the pouches to be produced, is so finely meshed, that the maggots are reliably enclosed in the pouch. The mesh width of the material, that is, its pore size, is so dimensioned, that an unimpeded fluid exchange of the digestive secretions of the maggots and the dissolved and liquefied necrotic tissue is possible. Further, the textile material of the pouch is sufficiently air permeable to ensure the survival of the maggots.
The fly larvae bred in sterile conditions are introduced into the pouch. It is also possible to introduce fly eggs into the pouches, so that the maggots emerge in the pouch. In order to keep the maggots alive until introduction into the wound, it is possible or necessary, for example, to introduce a maggot specific nutrient media together with the maggots, or to impregnate the pouch therewith. Since the maggots only sustain themselves with dead tissue, such a supplementation of nutrient media can also be important in the case that the wound area, in which the pouch is applied, does not sufficiently contain necrotic tissue.
For the practical application of the wound overlay, it can be of advantage to provide large surface area pouches which can, for use, be cut to size to correspond to the wound. For this, the pouch can be subdivided by suitable means, for example by plastic clamps or adhesive material, so that a separation is possible and after the separation, the partial pouch is closed at the line of separation. It can also be of advantage, when a large surface area wound overlay is provided, for example, in sheets, which is subdivided into small closed chambers, each of which respectively contain a few maggots. This wound overlay can, on the basis of the confinement in chambers, be very simply cut to the required shape. The subdivision into chambers ensures that the maggots are maintained evenly distributed over the entire surface area of the wound overlay and evenly dispensed their secretion.
In the place of pouches, in which living maggots are enclosed, it is also possible to employ a wound overlay which contains no living maggots but instead is permeated with the secretion of maggots. For this, maggots are bred in vitro and fed necroticed tissue, so that they form and release secretion. This secretion is then received and stored in a wound overlay. After removal of the maggots, the wound overlay impregnated with secretion can be applied to the wound. Such a wound overlay without living fly larvae is particularly suitable for such applications, in which in particular the anti-bacterial and healing promoting effect of the secretion is desired. However, it is usually also necessary to remove necrotized tissue from the wound, and in this case the wound overlay with enclosed maggots is to be preferred.
Particularly in the case of large and deep wounds, in order to apply the wound overlay to the wound surface with good contact, it is preferable when the bandage supplementally includes a core or enclosure, which is applied upon the wound overlay and secured by an outer wound covering. The wound covering presses the core or insert against the wound overlay, whereby again the wound overlay is brought into good contact with the wound surface. The core or insert is preferably comprised of an open-pore material, in particular a foam plastic. As outer wound covering a plastic foil is preferably employed, which is applied over the wound and adhered to the wound edges. Such a foil as wound covering has the advantage, that the wound is closed off air-tight, whereby the development of the offensive strong odor of necrotic tissue is prevented.
If the insert is comprised of an open-pore foam material, then the insert can take up and store surplus wound secretion. In the application of pouches with living maggots, the open-pore insert also serves as storage area for air and moisture, which is necessary for the survival of the maggots when the wound is closed over with an air-tight foil.
If living maggots are employed, then it is advantageous when the air-tight covering of the wound is combined with a ventilation system. By means of such a ventilation system sufficient air can be introduced under the foil and into the open-pore insert, in order to ensure the survival of the maggots. In order to prevent the escape through the ventilation system of the odors evolved in the wound, the ventilation system is preferably closeable or sealable. When air is being supplied below the air-tight covering, the ventilation system is opened and the flow-through of air is carried out through the open porous insert. The emitted odors can, as desired, be captured by an odor filter. Between the individual ventilation phases, the ventilation system can be closed by an air-tight lid.