Cold plasma jet arm: Immediately after removal of the dressing, the wound will be cleaned with a physiological saline solution soaked swab. If > 30% fibrin coating or dry necrosis remaines after cleaning, debridement is required before treatment. The treatment scheme of the cold plasma jet will be applied in the following manner, quantity and frequency: Cold plasma is always applicated for 30 seconds/ cm^2 wound size. Wounds will be treated three times in the first week, twice in the second week and once per week in the following observation period. In case of locally infected ulcers, treatment will be performed 1x per day during the first week and afterwards in the same manner as in non-infected ulcers. After application of cold plasma, the wound will be covered with Adaptic perforated gauze and a non-active dressing. Dressing change will be performed after treatment and at least every 2nd day, on weekends every 3rd day; in the case of locally infected wounds, dressings will be changed daily. The application of cold plasma will be performed always by the examiner. Dressing changes beyond visits can also be performed by the general practitioner, a nursing service or by the participant him- or herself.~Best Practice treatment arm: Immediately after dressing removal, the wound will be cleaned with a physiological saline solution soaked swab. In case of locally infected wounds, an antiseptic will be used instead of the physiological saline solution. Subsequently, a wound phase-adapted primary dressing will be applied according to the experience of the practitioner and, if necessary, the wound will be covered with a secondary dressing according to the experience of the practitioner as well. In case of locally infected wounds, silver dressings can be applied. The dressing will be changed at least every 2nd day and on weekends every 3rd day; in case of locally infected wounds, dressings will be changed daily. Dressing changes beyond visits can also be performed by the general practitioner, a nursing service, or by the participant him- or herself.~In case of a venous leg ulcer, a modern compression system will be applied for compression in both study arms.
Within the treatment of chronic wounds the main objective is to analyze the wound healing properties with cold plasma (cold plasma jet kINPen® Med) compared to wound phase-adapted best practice wound dressings. Especially, close attention is paid to the development of the different phases of the chronic wounds until healing during the study.