**1. Introduction**

The evolution of knowledge about the biology of wound healing makes it possible to predict the sequence and prognosis of the events that occur in this complex process. However, there are wounds in which healing can be either prolonged over time or not fully achieved [1, 2].

Therefore, The keys to providing adequate and efficient treatment involve identifying, as soon as possible, the combination of either internal or external factors that contribute to the complexity of the wound and affect the healing process, and to detect at an early stage when it is likely that a wound would be slow or difficult to heal.

The actions undertaken should be aimed at reducing the aspects that lead to complexity, including factors related to the patient, the wound, relationships with healthcare personnel, and available resources. Only by assessing and understanding the interaction between these factors and their effect on healing will it be possible to develop efficient and appropriate strategies for improving results. Similarly, certain characteristics of the wound, such as its anatomical location, time duration, size, depth, and the state of the wound bed, are correlated with adequate healing [3–5].

The presence of necrotic tissue, crusts, slough, or foreign bodies in the wound bed, which are all obstacles for wound assessment, can lead to a delay in healing, and they can also be a focus of infection. Therefore, it is important to provide frequent, extensive, and efficient debridement until healthy tissue is found [6]. There are other situations that can have an influence and cause healing to fail, such as ischemia. Poor perfusion deprives tissue of an efficient oxygen and metabolic exchange, and causes an increase in vascular permeability, leukocyte retention, synthesis and the liberation of oxygen free radicals and proteolytic enzymes [7]. Inflammation in chronic wounds brings about a prolongation in healing time, resulting in an exacerbated inflammatory reaction, which in turn causes the hyperproduction of pro-inflammatory cytokines and proteolytic enzymes. This activity is combined with a decrease in the secretion of metalloproteinase tissue inhibitors, and it intensifies as the wound bed pH alters. As a consequence, we find that in the wound bed there is a sustained inflammation with matrix degradation, a limited bioavailability of growth factors and intense fibroblast aging, all of which reduce tissue repair, cell proliferation, and angiogenesis [8, 9].

In the same way, chronic wounds are characterized by the presence of one or more bacterial strains, with antibiotic-resistant microorganisms, and the presence of biofilms within which the bacteria are protected against the action of the silver-based antimicrobials [10–13].

The initial response to treatment is indicative of the viability of the tissue and its capacity to heal. When a patient's wound does not heal in the planned period of time using conventional treatment, it is essential to reassess the patient and modify the therapeutic guidelines [14, 15].

Thus, tissue wound healing usually follows a predictable sequence, although in some cases, it is prolonged over time or it is never achieved. The wound healing process is the result of a complex interaction between the patient and wound factors, the treatment adopted, and the skills and knowledge of healthcare professionals. Only by carrying out a detailed initial assessment and repeated treatment assessment will it be possible to identify the factors that contribute to the complexity of the wound and to assess its potential state. The challenge for professionals is to utilize the most efficient therapeutic strategies at the right time and in the most cost-effective way, in order to reduce the complex nature of wounds, to treat the symptoms, and whenever possible, to achieve wound healing.
