## 4 Discussion  
Wound dressings fulfill various functions. On the one hand, they form a barrier function. and thus prevent microbial colonization of wounds. On the other hand, they should absorb wound secretions and create a sufficiently moist wound-healing environment, so that the skin is able to re-epithelialize well [18]. Depending on the type of wound dressing, these functions are emphasized to a greater or lesser extent. The range of wound dressings available on the world market is large and confusing [3]. There are different wound dressings for different indications. Even within the respective categories, there are differences of opinion among experts. Some argue that wound dressings should only be selected and used after careful scientific testing. Others believe that experience-based clinical expertise justifies the selection of the correct dressing for the particular wound [19]. In addition, both financial factors and physical availability play a role in the choice of dressing. Individual research areas exist for each wound-dressing category (e.g., dressings, burn plasters, scar plasters, skin substitutes). A very comprehensive paper examined 13 reviews or meta-analyses on the topic of wound dressings. SAWDS (standard advanced wound dressings) were examined: films, foams, gels, hydrocolloid dressings and hydrofibers. Typical areas of application frequently represented in the literature were venous ulcers, pressure ulcers, chronic wounds, surgical wounds and diabetic foot syndromes. It was shown that SAWDS and gauze produced similar results for venous ulcers. Hydrocolloid dressings also showed a better healing process for pressure ulcers and chronic wounds SAWDS. However, it was not possible to make a clear statement about which wound dressing achieves the best results [20]. The data situation is complex and multi-layered. It is not the aim of the present study to assess indications or qualities of individual wound dressings. The aim is to establish a trend in the direction of changes in skin properties under wound dressings. Only intact skin from healthy individuals was examined. The moisture content of the skin largely determines its physiological condition. Maintaining water homeostasis is crucial for the skin's ability to function [21]. The prerequisite for a healthy moisture balance is an intact stratum corneum, which is maintained by various types of connections (e.g., tight junctions) and the presence of lipids such as ceramides. These elements are influenced by various factors including environment, age, diet, circadian rhythm and ultraviolet radiation, all of which ultimately impact skin hydration [22]. The presence of aquaporins, transmembrane proteins that promote water transport, also plays an important role in the skin's water balance. They influence the regulation of body temperature, skin hydration and skin-healing processes [23]. Assessing the moisture status of a subject's skin is therefore extremely important on the one hand, but on the other hand it is complex and not easy to interpret. Measuring skin hydration also has clinical implications. For example, the wound-healing process in diabetic foot syndrome can be positively influenced by sufficiently high skin-moisture levels. Feet with sufficient skin moisture had to be amputated significantly less frequently [24]. Transepidermal water loss (TEWL) can be defined as the \"continuous invisible loss of water through the human skin\" [25]. This value provides important information about the barrier function of the skin. More than 30 years ago, it was already assumed that the TEWL value changes depending on the skin's state of health, in such a way that it is possible to distinguish physiological from pathological skin conditions [26]. Skin diseases such as psoriasis vulgaris or atopic dermatitis often lead to increased TEWL values. The measurement of the TEWL value, therefore, also plays a role in clinical applications for estimating the course of certain diseases [27].