**2. How should chronic and complex soft‐tissue wounds be managed?**

### **2.1. Management and treatment strategies**

**1. Introduction**

416 Wound Healing - New insights into Ancient Challenges

with adequate healing [3–5].

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

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

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

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

it is likely that a wound would be slow or difficult to heal.

which reduce tissue repair, cell proliferation, and angiogenesis [8, 9].

Chronic and complex soft-tissue wounds usually involve difficult healing, which means that they require an appropriate management-treatment strategy using a comprehensive and dynamic approach, applying new therapies to confront this old problem: wound healing [16]. In order to carry out this comprehensive approach, we should take into account the complex nature of the wound and its healing, its relationship with psychosocial factors and delays in wound healing, together with the economic cost for the patient, family, community, and the healthcare system. The steps to follow in order to achieve this approach should take into account the complete assessment of the patient, the control of causal factors, general healthcare, and the preparation of the wound bed.

### **2.2. Preparation of the wound bed**

The preparation of the wound bed is an essential and dynamic process that provides an appropriate framework for a structured approach to wound management. This notion stresses a comprehensive and systematic approach with the aim of assessing and eliminating barriers to the normal wound healing process. It develops the appropriate treatment strategies to be directed at the patient in general and for treating the underlying condition causing the wound. Its objective is to create an optimum healing setting, a well-vascularized wound, with a stable and balanced bed in terms of exudate production, aimed at reducing scar healing time and facilitating the efficiency of other therapeutic measures. The wound bed should be prepared in each phase of the wound healing process following an agreed-upon procedure.

The "Tissue, Inflammation-infection, Moisture, Edge" (T.I.M.E.) scheme, proposed by the European Wound Management Association (EWMA), is based on the research of the International Wound Bed Preparation Advisory Board (IWBPAB), which established an algorithm through the development of the acronym T.I.M.E., whose objective is to describe the characteristics of chronic wounds during wound bed preparation. Following on from this, the concept was updated by placing emphasis on the treatment of the cause of the wound and general patient factors during treatment, before dealing with local wound factors. This algorithm consists of four components that cover the different physiopathological alterations present in chronic wounds: the management and conditioning of non-viable tissue, the monitoring of inflammation and infection, the disequilibrium of moisture due to excess exudate, and the stimulation and progression of the wound edges. So we can see that the T.I.M.E. framework involves the overall strategies that can be applied to the management of different kinds of wound with the aim of maximizing the ability to heal wounds [16–18] (**Figure 1**).

**Figure 1.** Complex and traumatic soft‐tissue wound. Management and treatment of wound bed.

Wound treatment is initiated with a hydrodynamic washing using 0.9% saline solution at room temperature, with a 1–4 kg/cm effective washing pressure, without any damage being caused (a 20‐ml syringe, with a 0.9‐mm‐diameter catheter), and the surrounding area is washed with a soapy antiseptic solution consisting of chlorhexidine digluconate.

For the monitoring of the non‐viable tissues (necrotic tissue, crust, slough, and foreign bodies), episodic or continuous debridement is carried out until healthy tissue is found. It can be surgical, using tangential hydrodissection (Versajet™Plus, Smith & Nephew, London, United Kingdom); enzymatic, applying exogenous enzymes locally (collagenase, fibrolysine, trypsin, or chymotrypsin); chemical (cadexomer iodine); autolytic (due to the conjunction of three factors: hydration of the bed, fibrinolysis and the action of the endogenous enzymes on the devitalized tissue); or osmotic (hyperosmotic solutions). On occasions, an instillation therapy can also be used (VeraFlo™, KCI, Acelity LPI, San Antonio, TX) either in deep wounds with a viscous exudate or in uncontrolled infections on prosthetic materials, in order to eliminate the biofilm, reduce the pain, and reactivate healing. A noninvasive treatment option, for the debridement of chronic wounds, is low‐frequency guided ultrasound [3].

In the management of the bacterial load (a contaminated or colonized lesion, with critical or infected colonization), foci of local and/or systemic infection have to be removed, which is why it is necessary to clean and debride the wound; take a wound culture; monitor the wound proteases; and use topical antimicrobials (silver, cadexomer iodine), systemic antibiotics according to the antibiogram data, anti‐inflammatory drugs, and protease inhibitors if required.

It is important to monitor the exudate and achieve the equilibrium in the moisture, given that a dry wound makes it difficult for cell migration and exudate encourages infection and macerates the perilesional skin area. We should be aware that scarring is faster with wounds in an optimally moist environment in which the physiological and atmospheric conditions of the wound bed are maintained, thus fostering basal keratinocyte migration. A moist environ‐ ment also prevents cell desiccation, encourages cell migration, promotes angiogenesis, stimulates collagen synthesis, and facilitates intercellular communication. A moist wound environment preserves a slightly acid pH and a low oxygen tension on the surface of the wound [18–20].

Thus, the edges of the wound do not advance because there are keratinocytes that do not migrate, senescent cells, and alterations in the extracellular matrix secondary to the disequili‐ brium in protease activity.

### **2.3. Clinical protocols**

involves the overall strategies that can be applied to the management of different kinds of

wound with the aim of maximizing the ability to heal wounds [16–18] (**Figure 1**).

418 Wound Healing - New insights into Ancient Challenges

**Figure 1.** Complex and traumatic soft‐tissue wound. Management and treatment of wound bed.

a soapy antiseptic solution consisting of chlorhexidine digluconate.

debridement of chronic wounds, is low‐frequency guided ultrasound [3].

required.

Wound treatment is initiated with a hydrodynamic washing using 0.9% saline solution at room temperature, with a 1–4 kg/cm effective washing pressure, without any damage being caused (a 20‐ml syringe, with a 0.9‐mm‐diameter catheter), and the surrounding area is washed with

For the monitoring of the non‐viable tissues (necrotic tissue, crust, slough, and foreign bodies), episodic or continuous debridement is carried out until healthy tissue is found. It can be surgical, using tangential hydrodissection (Versajet™Plus, Smith & Nephew, London, United Kingdom); enzymatic, applying exogenous enzymes locally (collagenase, fibrolysine, trypsin, or chymotrypsin); chemical (cadexomer iodine); autolytic (due to the conjunction of three factors: hydration of the bed, fibrinolysis and the action of the endogenous enzymes on the devitalized tissue); or osmotic (hyperosmotic solutions). On occasions, an instillation therapy can also be used (VeraFlo™, KCI, Acelity LPI, San Antonio, TX) either in deep wounds with a viscous exudate or in uncontrolled infections on prosthetic materials, in order to eliminate the biofilm, reduce the pain, and reactivate healing. A noninvasive treatment option, for the

In the management of the bacterial load (a contaminated or colonized lesion, with critical or infected colonization), foci of local and/or systemic infection have to be removed, which is why it is necessary to clean and debride the wound; take a wound culture; monitor the wound proteases; and use topical antimicrobials (silver, cadexomer iodine), systemic antibiotics according to the antibiogram data, anti‐inflammatory drugs, and protease inhibitors if

It is important to monitor the exudate and achieve the equilibrium in the moisture, given that a dry wound makes it difficult for cell migration and exudate encourages infection and macerates the perilesional skin area. We should be aware that scarring is faster with wounds The preparation of the wound bed requires specific management protocols, which can be grouped into three sections following the T.I.M.E. procedure:



**Table 1.** Preparing the wound bed: management protocol (T/M).


**Table 2.** Preparing the wound bed: management protocol (I/M).


**Table 3.** Preparing the wound bed: management protocol (E/M).

After finalizing the preparation of the wound bed, the wound remains open ready for its closure by secondary intention with granulation tissue and the re‐establishment of the epidermis. At this point, the surgeon comes across two new problems: how to granulate the wound, and afterwards, how to epithelialize it.

#### **2.4. Wound granulation using negative topical pressure therapy**

For the granulation, we use a noninvasive topical negative pressure wound therapy (NPWT) (**Figure 2**), using aspirated drainage to eliminate the secretions, facilitate the closure and prevent complications. Its scientific fundamentals and physiopathology are based on the application of mechanical stress on the tissues, by creating a negative pressure on the surface of the wound [21]. The effect of the macrotension on the tissues is carried out using a sponge dressing (polyurethane‐polyvinyl alcohol), with open pores, that contract under the negative pressure, bringing the edges closer together [22], eliminating the exudate, the non‐viable tissue, and the soluble wound healing inhibitors (cytokines and matrix metalloproteinases) [23]. Other effects are a reduction in the edema, an increase in neutrophils and monocytes on the bacterial load and an improvement in local perfusion [24]. The effect of microtension, at the cell level, triggers cell stretching, which increases fibroblasts, the formation and division of new cells and the rapid growth of granulation tissue [25], the migration of fibroblasts to the area of the wound (displacing new cells to its surface), the formation of new blood vessels [26], and the formation of granulation tissue through mitosis stimulation. In this way, moist healing of the wound helps wound debridement (**Figure 3**).

The NPWT is contraindicated when either the wound has not been well explored, it has necrotic tissue with eschar or it has weakened blood vessels due to irradiation or suture. Also, NPWT is contraindicated in case of intestinal anastomosis, exposed nerves, the presence of tumors or untreated osteomyelitis. Equally, it is not advisable for either enterocutaneous or enteroatmo‐ spheric fistulas. Finally, active bleeding wounds and/or patients treated with anticoagulants are not suitable for NPWT treatment.

The Use of Amniotic Membrane in the Management of Complex Chronic Wounds http://dx.doi.org/10.5772/64491 421

**Figure 2.** Complex and traumatic soft‐tissue wound. Treatment with TNP therapy.

**Protocol 3: (E/M = Edges and moisture)**

**‐Wounds in the granulation phase**

‐Type of wound ‐Granulation tissue

‐Moist dressing ‐Hydrocellular with acrylic

**‐Dressing every 72 h**

**‐Epithelialization of edges and moisture monitoring**

420 Wound Healing - New insights into Ancient Challenges

‐Low or moderate exudate

adhesive or silicone adhesive

**Table 3.** Preparing the wound bed: management protocol (E/M).

wound, and afterwards, how to epithelialize it.

of the wound helps wound debridement (**Figure 3**).

are not suitable for NPWT treatment.

**2.4. Wound granulation using negative topical pressure therapy**

‐Granulation ‐Collagen with silver protease modulator matrix or ‐Powder collagen

‐Granulation tissue ‐High exudate

After finalizing the preparation of the wound bed, the wound remains open ready for its closure by secondary intention with granulation tissue and the re‐establishment of the epidermis. At this point, the surgeon comes across two new problems: how to granulate the

For the granulation, we use a noninvasive topical negative pressure wound therapy (NPWT) (**Figure 2**), using aspirated drainage to eliminate the secretions, facilitate the closure and prevent complications. Its scientific fundamentals and physiopathology are based on the application of mechanical stress on the tissues, by creating a negative pressure on the surface of the wound [21]. The effect of the macrotension on the tissues is carried out using a sponge dressing (polyurethane‐polyvinyl alcohol), with open pores, that contract under the negative pressure, bringing the edges closer together [22], eliminating the exudate, the non‐viable tissue, and the soluble wound healing inhibitors (cytokines and matrix metalloproteinases) [23]. Other effects are a reduction in the edema, an increase in neutrophils and monocytes on the bacterial load and an improvement in local perfusion [24]. The effect of microtension, at the cell level, triggers cell stretching, which increases fibroblasts, the formation and division of new cells and the rapid growth of granulation tissue [25], the migration of fibroblasts to the area of the wound (displacing new cells to its surface), the formation of new blood vessels [26], and the formation of granulation tissue through mitosis stimulation. In this way, moist healing

The NPWT is contraindicated when either the wound has not been well explored, it has necrotic tissue with eschar or it has weakened blood vessels due to irradiation or suture. Also, NPWT is contraindicated in case of intestinal anastomosis, exposed nerves, the presence of tumors or untreated osteomyelitis. Equally, it is not advisable for either enterocutaneous or enteroatmo‐ spheric fistulas. Finally, active bleeding wounds and/or patients treated with anticoagulants

‐Hydrocellular with acrylic adhesive or silicone adhesive

‐Collagen with silver protease modulator matrix or ‐Powder collagen + alginate

**Figure 3.** Complex and traumatic soft‐tissue wound. Completed granulation after TNP therapy.

### **2.5. Epithelialization of the chronic and complex soft‐tissue wounds**

A large variety of wound coverings and procedures have become available over the past two decades, including several types of synthetic dressings and allo‐skin or auto‐skin substitutes, although their cost is too high for routine clinical practice [27, 28]. New technologies involving growth factors and bioengineered tissues are relatively new and have produced relatively good results; however, they are quite expensive.

### **2.6. Amniotic membrane and wound healing**

Amniotic membrane (AM), the innermost layer of the placenta, has a fetal origin and can easily be separated from the placenta by blunt dissection. AM, due to its special structure, biological properties and immunological characteristics, is a tissue of particular interest as a biological dressing. AM exhibits low immunogenicity and well‐documented reepithelialization effects. Moreover, AM shows anti‐inflammatory, antifibrotic, antimicrobial, analgesic and nontumori‐ genic properties. This diversity of its effects is related to its capacity to synthesize and release biologically active molecules including cytokines and signaling factors such as tumor necrosis factor (TNF)‐α, transforming growth factor (TGF)‐α, TGF‐β, basic fibroblast growth factor (b‐ FGF), epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatic growth factor (HGF), interleukin‐4 (IL‐4), IL‐6, IL‐8, natural inhibitors of metalloproteases, β‐defensins, and prostaglandins among others [29–31]. Moreover, AM is a biomaterial that can be easily obtained, processed, and transported. On the other hand, AM may function as a substrate where cells can easily proliferate and differentiate [32]. When compared to skin transplanta‐ tion, AM treatment offers considerable advantages. Its application does not produce rejection because it has low immunogenicity and does not induce uncontrolled proliferation [33]. All these effects are related to its capacity for the production and release of biologically active substances (see above).

AM has been applied in medicine for more than 100 years. In 1910, Davis [34] reported a comprehensive review of 550 cases of skin transplantation to various types of burns and wounds using natural AM obtained from labor and delivery at the Johns Hopkins University. In 1913, Sabella [35] and Stern [36] separately reported on the use of preserved AM in skin grafting for burns and ulcers. Since then, there have been several reports of the uses of AM in the treatment of wounds of different etiologies and other applications: first, in the reconstruc‐ tive surgery of different tissues and organs including the mouth, tongue, nasal mucosa, larynx, eardrum, vestibule, bladder, urethra, vagina, and tendons [37–43]; second, as a peritoneum substitute in reconstruction procedures of pelvic exenteration surgery; third, in adherence prevention in the abdomen and pelvic surgery; and finally, as a covering of onphaloceles and the like [34–37, 44].

In ophthalmology, the use of AM was reported for the first time in 1940 by De Rötth, who used fresh fetal membranes, namely amnion and chorion, at the ocular surface as a biological dressing in the management of conjunctival alterations [45]. Later, Sorsby et al. [46] used preserved AM as a temporary coating in the treatment of acute caustic ocular lesions. Even though the results were favorable, its use was abandoned for almost four decades. In 1995, with the reconstitution assays of rabbit corneas with limbic disorder using human preserved AM, by Kim and Tseng [47], there was a renewed widespread interest in the use of AM in ophthalmology. Several publications appeared related to the efficacy of the AM in various ocular surface conditions and in diseases like epidermolysis bullosa [44, 48, 49]. Nowadays, AM is a resource widely used in ophthalmology [49–51] and to a lesser degree in the treatment of wounds, burns lesions, and chronic ulcers of the legs [48, 52–54] and in other surgical and nonsurgical procedures [38–43, 55–59].
