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Technical Guide APPLIED MANAGEMENT AND USING THE WOUND CONTINUUM IN PRACTICE

David Gray, Richard White, Pam Cooper, Andrew Kingsley

Assessing a patient with a wound involves accurate assessment of both the wound and the patient’s health status. The Applied Wound Management framework utilises three different continuums, each relating to a key wound parameter, the Wound Healing Continuum, the Wound Continuum and the Wound Continuum.

The Applied Wound Management The AWM system aids this type proceed effectively without (AWM) framework utilises of decision-making, reducing the a moist wound environment three different continuums, risk of poor practice and litigation. (Parnham, 2002). each relating to a key wound parameter: Using the Wound Healing Yellow and fibrous wound 8 Wound Healing Continuum Continuum to assess tissue that adheres to the wound bed (WHC): is represented by the Wound tissue types and cannot be removed on tissues in the wound and is a If left to heal by secondary irrigation is known as slough colour-based continuum. intention, the tissues in a (Tong, 1999). This adherent, 8 Wound Infection Continuum wound (within the wound bed fibrous material is derived from (WIC): is subdivided into and margins) indicate the the , and named stages representing relevant present, (Tong, 1999). In combination with varying host responses to reflect the state of healing and, wound exudate, it serves as an bioburden, each identified by consequently, the success of the ideal environment for bacterial clinical cues. management approach. Thus, growth and, consequently, 8 Wound Exudate Continuum a black wound (as opposed to infection (Davies, 2004). It also (WEC): is represented by black skin changes in melanoma, impairs healing by restricting volume and consistency or frostbite) indicates re-epithelialisation (Kubo et al, parameters, and each can be the presence of eschar or 2001). The clinical objective of graded according to a ‘matrix’ (Bale, 1997). Wound managing a sloughy wound is continuum. eschar is full-thickness, dry, to debride (Tong, 1999; devitalised (dead) tissue that has Hampton, 2005). This practical application to arisen through prolonged local everyday wound care enables ischaemia. In relation to pressure The red, moist tissue in a wound the practitioner to approach ulcers, eschar might arise after is a combination of new logically a sudden large vessel occlusion vessel growth (), and and systematically. Increased caused by shearing a matrix of (connective workloads across the NHS (Witkowski and Parish, 1982). tissue or dermal cells), known as require decision-making to be Unless removed, the eschar will . This is usually systematic, clear and coherent. delay healing, as healing cannot indicative of a healing wound and

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which disrupt the proteins that bind the dead tissue to the body (Schultz et al, 2003). The process can be enhanced by the application of wound management products which promote a moist BLACK BLACK/YELLOW YELLOW YELLOW/RED RED RED/PINK PINK environment. These products can 6 5 4 3 2 1 0 be divided into two categories: Figure 1. The Wound Healing Continuum. those that donate moisture to is often accompanied by signs Society [ETRS], 2003). The types of the dead tissue, and those that of re-epithelialisation (epidermal treatment available can be divided absorb excess moisture produced regrowth) (Gray et al, 2003). It is into three separate categories: by the body. Both are designed important to remember that not all 8 Active to facilitate the autolytic red are healthy; they may 8 Autolytic (moisture donation). debridement process. be critically colonised and non- 8 Autolytic (moisture absorption). healing/static, or show evidence of Clinical use of debridement haemolytic bacteria (if a dull brick- Active debridement techniques red colour) (Dowsett et al, 2004). 8 Surgical debridement: this Treatments from more than one involves removing the dead group may be required to achieve The approach taken in the tissue from the wound bed. full debridement of the wound. Wound Healing Continuum is to It is usually carried out under The heel presented incorporate intermediate colour surgical conditions and results in Figure 2 shows necrotic tissue combinations between the four in a wound bed. which has been rehydrated using key colours (Figure 1). To use this It removes dead tissue and an autolytic (moisture-donating) system to the optimum clinical results in an inflammatory treatment. This results in necrotic benefit, it is first important to response from the wound, thus eschar lifting at the wound margins identify the colour that is furthest stimulating healing (Bale, 1997) and separating from the slough to the left of the continuum. 8 Sharp debridement: this below. The necrotic tissue is For example, if the wound technique involves debulking the categorised as ‘black’ on the contains yellow slough and wound of slough and necrotic Wound Healing Continuum. red granulation tissue, it would tissue. This process requires be defined as a ‘yellow/red the use of surgical instruments, In Figure 3, the wound has been wound’. A key objective of the such as a specialist wound subjected to sharp debridement consequent wound management debridement pack and the necrotic tissue removed to plan would be to remove the 8 Larval therapy: the larvae liquefy leave the slough below exposed. yellow tissue and promote the the dead tissue and, where The wound is now categorised growth of red granulation tissue the treatment is successful, as a ‘yellow’ wound on the (Gray et al, 2005). can result in rapid debridement Wound Healing Continuum. No (Thomas et al, 1998). bleeding or pain has been caused. Identifying and obtaining Following sharp debridement, the treatment objectives Autolytic debridement patient is treated with a moisture- Debridement Autolytic debridement is the donating product (eg. hydrogel) to Where the wound exhibits removal of devitalised tissue from continue the process of autolytic dead tissue, eg. black, black/ the wound by means of the body’s debridement. yellow, yellow, or yellow/red, a own enzymes operating in a key treatment aim should be the moist environment. Where tissue The wound in Figure 4 is producing debridement of the devitalised can be kept moist it will naturally high levels of moisture which need tissue, unless contraindicated degrade and deslough from the to be absorbed. The wound bed by the patient’s overall physical underlying healthy structures. This is covered with slough which condition or process, such process is facilitated by enzymes requires debriding. The wound as PVD (European Tissue Repair (matrix ) is categorised as a ‘yellow/red’

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categorised as ‘red’ or ‘red/ pink’, the main objective is the promotion of granulation tissue and then epithelialisation. Granulation (red) and epithelial (pink) tissue are the final two stages of the Wound Healing Continuum.

Active treatment Topical negative pressure therapy (VAC® – vacuum assisted closure) Figure 2. Black wound. is used in the management of large granulating wounds, particularly cavity wounds. A foam pad is placed into the wound, which is then sealed and negative pressure applied via a vacuum pump. This facilitates the promotion of granulation tissue as well as removing excess exudate (Moore, 2005).

Moisture donation Figure 3. Black/yellow wound post sharp debridement. The fragile nature of granulation tissue means that it has to be kept moist to prevent desiccation and delayed tissue growth. Products such as hydrocolloids, hydrogels and honey, can all deliver moisture to the wound bed, thus supporting granulation. Hydrocolloids, sheet hydrogels and sheet honey dressings can also provide an element of moisture absorption (Cooper, et al, 2003), but this is not their main function which is that of moisture donation.

Moisture absorption An excess of moisture on the wound bed can lead to Figure 4. Yellow/red wound. maceration of the wound margins and delayed healing (Cameron and Powell, 1992). Alginates, cadexomer iodine, wound on the Wound Healing stage of the Healing Continuum — products, foams and Hydrofiber®) Continuum. By utilising an autolytic ‘red’ (Figure 5). absorb exudate, providing (moisture-absorption) treatment, the ideal environment for the the wound is successfully debrided Granulation and epithelialisation promotion of granulation tissue and has moved on to the next Where a wound has been and epithelialisation of the wound.

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Promotion of granulation and epithelial tissue in clinical practice In Figure 6, the patient has presented with an to the knee. The wound is categorised as ‘red’ on the Wound Healing Continuum. Depending on the outcome of the assessment, the correct product selection will lead to a ‘pink’ wound as seen in Figure 7.

Using the Wound Infection Continuum to assess bioburden While all chronic wounds left to heal by secondary intention will contain bacteria throughout, it is the delicate balance between the host (immune) response and the Figure 5. Red wound. pathogen that must be managed if infection is to be avoided (Casadevall and Pirofski, 2000). The mere presence of colonising bacteria in a is usually of no clinical significance, as this level of bioburden does not impair healing (Leaper, 1994).

From a clinical management perspective, it is the recognition of the state of the wound — with respect to the infection status — that is the challenge. The key to good wound management is to avoid infection. It is important to Figure 6. Red wound. recognise the subtle signs and symptoms that precede infection, and to intervene accordingly. These factors are included in the evolving ‘Wound Infection Continuum’ and the related treatment guidelines.

The concept for building a bridge between microbiological theory and clinical practice is called the Wound Infection Continuum. This continuum seeks, in a highly simplified form, to align the states of colonisation, critical colonisation, local infection and Figure 7. Pink wound. spreading infection, with the Technical Guide probable bacterial bioburden and states of microbiological and The presence of a spreading host response, thereby enabling immunological activity. infection associated with an open the practitioner to interpret what wound is a systemic disease, is happening. In particular, it Each successive stage from which requires a systemic is possible using the Wound left to right on the Continuum response. As such, the choice Infection Continuum to guide the (Figure 8), involves an increase in of will have little impact appropriate use of the plethora of the quantity of microbes, a new on the spreading infection. A new therapies that pathogen arrival, an increase in systemic response, in the form are now available. This makes for the quantity of virulent organisms, of antibiotics, is likely to be the good ‘prescribing’ in terms of both or an increase in the virulence treatment of choice. clinical- and cost-effectiveness. (Wilson et al, 2002) of the collective species mixture through bacterial Localised infection: remove infection Infection, critical colonisation synergy (Bowler et al, 2001). The from surrounding tissue and reduce and colonisation situation may shift in favour of the wound bioburden The normal microbiological state microorganisms if the host immune Some authors suggest that a of a healing wound is that of response is impaired or suddenly localised infection can be treated colonisation, which represents a reduced (Heinzelmann et al, 2002). using topical alone, stable state where growth and In addition, shift may result from the without recourse to antibiotics death of organisms is balanced or presence of potentiating factors, (European Pressure Ulcer Advisory below the immune system’s healing such as the introduction of foreign Panel [EPUAP], 1999). Others, disruption threshold (Heinzelmann bodies that reduce the necessary however, recommend the use of et al, 2002). inoculum needed to produce topical antimicrobials with oral a worsening microbiological antibiotics (Kingsley, 2005). Where This classification has been used environment. the practitioner is satisfied that the to provide guidance on the route patient’s overall condition does not of administration for systemic Identifying and obtaining suggest a high risk of the infection antibiotics. Schultz et al (2003) treatment objectives developing into a spreading describe four levels of microbial The Wound Infection infection, it would seem reasonable interaction: Continuum is a useful adjunct to adopt a topical antimicrobial- 8 Contamination to the identification of treatment only approach. However, the 8 Colonisation objectives (Gray et al, 2005). At practitioner should remain alert to 8 Critical colonisation different stages of the Continuum, the possibility of an exacerbation 8 Infection. there is likely to be the need for a of the infection, and be prepared different treatment objective. to alter the treatment as required. Edwards and Harding (2004) In addition, it would be valuable include two further levels: Spreading infection: remove blood to set a period of time from the stream infection and reduce wound outset in which a reduction of 8 Spreading invasive infection and surrounding tissue bioburden signs and symptoms of infection 8 Septicaemia.

Dow et al (1999) and Schultz et al (2003) utilise, with other factors, a ring of cellulitis of < 2cm to suggest antibiotic treatment via oral route, with extensive cellulitis (by absence of further definition presumed to be > 2cm) requiring intravenous therapy. SPREASING INFECTION LOCAL INFECTION CRITICAL COLONISED COLONISED The stages in the Wound Infection 3 2 1 0 Continuum identify different Figure 8. The Wound Infection Continuum.

136 Wound Essentials • Volume 5 • 2010 Technical Guide would be expected to start (eg. < 7 bacteria as they pass into the effect the removal of dead tissue days or perhaps by the return of dressing (passive). and the formation of new tissue. swab culture results), as it would be inappropriate to allow pain to Using the Wound Exudate Assessing exudate continue unnecessarily or for the Continuum to aid wound Traditionally, exudate has been wound bed to deteriorate. assessment described in terms of its perceived Wound healing occurs in four volume, eg. as light/low, moderate, Critical colonisation: reduce overlapping phases: haemostasis; or heavy (Watret, 1997). This form wound bioburden ; granulation/ of assessment is subjective and In critically colonised wounds, the epithelialisation; and tissue difficult to quantify in the absence level of bacteria must be reduced remodelling (Davidson, 1992). of significant investigation, such for healing to occur. The topical Upon injury, as the weighing of dressings pre- application of an antimicrobial is occurs with the aim of reducing and post-use (Thomas, 1997). probably the most effective way blood loss. Haemostasis is Vowden and Vowden (2003, 2004) in which to reduce the critically achieved by the formation of a clot, suggest that exudate volume colonised wound bioburden to which seals the wound. Following should not be viewed in isolation, levels that allow the wound to heal haemostasis the inflammatory but in conjunction with viscosity. (Cooper, 2004). process begins, during which The authors suggest that wound wound exudate is produced by the exudate volume and viscosity be Colonised: maintain wound tissues surrounding the wound. assessed by: bioburden Normal serous exudate is essential 8 Considering the exudate that is Wounds that are identified as to the healing of the wound (Field retained within the dressing colonised do not require any and Kerstein, 1994). However, 8 Noting the number of dressing form of topical antimicrobial as wound exudate is not always changes required in forty-eight the wound bioburden is in a ‘normal’ in terms of volume and/ hours healthy state. Only where there or consistency; it can present 8 Visual inspection of the wound. are concerns regarding the significant management challenges patient’s immune response, or and be a sign of underlying The Wound Exudate Continuum overall medical condition, should problems relating to the wound (Figure 9) is offered as an aid to topical antimicrobials be used bioburden (Cutting, 2004; Vowden quantifying the volume and viscosity prophylactically, for example, and Vowden, 2003, 2004). of wound exudate. The gradings wounds with a history of recurrent for both of these features are ‘high’, infection, including some diabetic Where a wound is healing without ‘medium’ and ‘low’, and allow foot ulceration and wounds complication, exudate can be wound exudate to be categorised on lymphoedematous limbs. considered a normal feature. It by a numerical score. For example, The indiscriminate prophylactic is produced when blood vessels a wound with exudate of low use of antimicrobials is to be dilate, post-haemostasis, as part volume and of medium viscosity discouraged. of the inflammatory process. would be in the low/medium Endothelial cells swell and so open category and would score 4 (placing Wound products used to attain gaps in the vessel wall, permitting it in the low exudate [green] portion treatment objectives extravasation of serous fluid. The of the continuum). Any score in Topical antimicrobial dressings vary presence of this fluid in the tissues the green zone should be seen as in their presentation and action in surrounding the wound contributes advantageous to wound healing. the wound. The wound treatments to localised pain, heat, and If the wound exudate score is 6, available are categorised into two swelling; symptoms associated then this places the wound in the distinct groups: active and passive. with inflammation. amber zone. Wounds that are These terms describe the mode of assessed as being in the amber the respective dressings, as some Wound exudate has a key role to zone require careful consideration, dressings donate antimicrobial play in the moist wound healing as this category could either properties into the wound (active), process as it provides not only indicate an improvement or and others seek to act upon the moisture, but also factors, which deterioration in the wound’s

Wound Essentials • Volume 5 • 2010 137 Technical Guide condition. For example, if the When these objectives are added have an antimicrobial function previous recording had been in the to the objectives identified using when combined with ; namely, green zone, the practitioner should the Wound Healing and Wound silver alginate and Hydrofiber® plus seek to identify why the wound has Infection Continuums, a clear silver. The dressing has moved (deteriorated) into the amber picture of the overall treatment no antimicrobial function, but has zone. A change in score to red objectives is achieved. a large capacity to absorb fluid from amber, ie. a deterioration, may and wick it away from the wound be because of an alteration in the Once an assessment has been bed. All of these primary dressings wound bioburden, indicating critical carried out and a colour zone require a secondary dressing to colonisation or the development identified using the Wound Exudate cover them. of an infection. However, if the Continuum, it is possible to identify previous score had been in the which product may be suitable. Primary/secondary dressings red zone, an amber score would The dressings in these categories indicate an improvement in the Product functions can be applied as primary condition of the wound. Any Device/dressings dressings (which do not require a score in the red zone should be In this category there are two secondary dressing), such as the investigated urgently as this may different products. First, VAC® hydrocolloids, hydrogel sheets or indicate local or spreading infection, (topical negative pressure), which film dressings. particularly if the previous score had works by applying negative not been in this zone. pressure to a wound bed and Foam dressings can act as a thus removing the exudate via a primary dressing, but are also Identifying and obtaining tube to a canister. frequently used as secondary treatment objectives dressings, absorbing exudate Any wound assessed as having This product can function across which has passed through the both high viscosity and high volume the spectrum of exudate zones. A primary dressing. of wound exudate, would score a Wound Manager™ (ConvaTec) is full 10 points and be regarded as a device similar in construction to Some products in these categories causing serious concern. It is likely a colostomy bag, which acts as contain antimicrobial agents, and that such a wound may indicate a a reservoir where there are large there are products which can also spreading infection, sinus or fistula amounts of exudate. Generally, donate moisture to the wound bed formation, or some other cause the Wound Manager™ has a as required. WE for concern. Regardless of the short-term application in acute zone, the assessment points to situations such as dehisced the treatment objectives will fall into abdominal wounds. one of three categories: A complete version of this article 1. Absorb moisture. Primary dressings can be read in the book Essential 2. Maintain current moisture These dressings are applied directly Wound Management, which is balance. to the wound bed and absorb available atwww.woundsuk.com 3. Donate moisture. exudate. Two classes of dressings Bale S (1997) A guide to wound VISCOSITY debridement. J Wound Care 6: 179–82 VOLUME HIGHT 5 MEDIUM 3 LOW 1 Bowler P, Duerden B, Armstrong HIGH 5 D (2001) Wound microbiology and associated approaches MEDIUM 3 to wound management. Clin Microbiol Rev 14(2): 244–69 LOW 1 Cameron J, Powell S (1992) Contact dermatitis: its Figure 9. The Wound Exudate Continuum.

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