Wounds may occur during many diseases and traumatic injuries, with types varying according to the source of the causal agent. Wound healing is a complex series of interlinked and co-dependent events that consist of haemostasis, coagulation, migration of cells, inflammation, cell proliferation and differentiation, matrix repair, epithelialisation and remodelling of the scar tissue.^9,10 This process involves a balance between growth factors, pro-inflammatory cytokines and their inhibitors; matrix metalloproteinases (MMPs) and their inhibitors.¹⁰ All these elements are responsible to initiate the inflammatory phase that lasts more or less than for4 days (with a peak 5–7 days after initial injury). This is followed by the repair phase with proliferation and migration of fibroblasts, production of collagen and neovascularization. There is a migration of epithelial cells from wound edges and cells niches in hair follicles and sweat glands. This is followed by the contraction of the wound because of the differentiation of fibroblasts into myofibroblasts. This initial scar matrix is then remodelled for the next 6–12 months.¹⁰

In acute wounds (i.e. post-surgery and post-traumatic), the healing process happens in an orderly and timely fashion, while in chronic wounds (i.e. pressure injuries, leg ulcers and diabetic foot ulcers), there is a ‘stop’ in the orderly healing process because of a lack of cell division, increased levels of pro-inflammatory cytokines (resulting in excess inflammation), an imbalance and increase in the levels of MMPs causing degradation of tissue and growth factors and the cells becoming senescent.^10,11 Consequently, the wound becomes ‘stuck’ in the inflammatory and proliferative stages of healing, taking more than 6 weeks to heal.¹²

If no systemic (e.g. nutritional status, anaemia, chronic diseases) or local factors (e.g. presence of a foreign body, haematoma/seroma, infection, wound dehiscence) cause a delay in the wound healing process, a wound is supposed to heal by epithelial regeneration, primary closure or primary intention. However, in the presence of systemic or local factors that delay wound healing, where possible these factors should be addressed by the appropriate intervention, for example, correcting the nutritional status and anaemia, removing the foreign body or treatment of wound infection. Where local factors cannot be ameliorated such as wound dehiscence, wounds may be left to heal by secondary intention or spontaneous healing, followed by delayed closure or tertiary intention.^13,14

A wound is considered healable:

Some wounds are referred to as maintenance wounds when the cause of the wound for some reasons cannot be treated, but the blood supply is adequate. In other words, if other factors can be managed, the wound will probably heal. Maintenance wounds may represent a stage during the treatment, where the wound is stalled in the progression for healing; the physician should then reassess the systemic factors affecting the healing progress. Non-healable or palliative wounds imply that all three factors above are affected, that is, the cause cannot be treated, blood supply is often inadequate and co-factors may inhibit healing.¹⁵ Examples of wounds where palliation or maintenance could be the treatment goal include bedbound patients with very poor nutritional status and are unfit for surgery, patients with advanced human immunodeficiency virus (HIV) disease that has a poor prognosis, patients with metastatic cancer receiving palliative care or advanced cancer wounds. It is important to recognise these factors to decide what has to be changed in the treatment plan and initiate the early involvement of a multidisciplinary team to make a proper assessment of correctable factors that stall the progression to healing.¹⁷ This will prevent unnecessary costs and unnecessary wastage of expensive dressings.

Wound bed preparation is the ‘management of a wound to accelerate endogenous healing or to facilitate the effectiveness of other therapeutic measures’.^18,19 Frameworks or enablers have been proposed with structured approaches to wound management to help clinicians optimise conditions at the wound bed aiming to reach wound healing.¹² The most popular WBP frameworks are the acronyms TIME (tissue, inflammation/infection, moisture, edge) and DIME (debridement, inflammation/infection, moisture, edge).

TIME framework (Figure 1) has four components: Tissue management; control of Infection and Inflammation; Moisture balance and advancement of the epithelial Edge of the wound.^12,15,18,19 An ‘S’ was added later to represent the surrounding skin, currently considered as the peri-wound tissue.²⁰

Tissue may be:

For epithelial cells to migrate across the wound surface, a well-built extracellular matrix is required. Hence the need to identify and address the presence of devitalised tissue usually with some form of debridement. Debridement should be conservative if the blood flow to the wound area is affected.¹² Although surgical debridement is used commonly, other modalities such as chemical debridement, enzymatic debridement and using a water jet can also be utilised for certain wounds.²¹

Wound infection can be characterised as a continuum where the progression of infection in a wound aligns with the phases of infection detected in the wound and with the clinical response of the individual to the wound.²² The stages within this continuum process include^22,23:

Topical antimicrobials (such as silver-based topical antimicrobials) are indicated from the stage of local infection, and systemic antimicrobials when spreading infection is diagnosed.²³ The presence of biofilm, that is, a community of micro-organisms surrounded by an extracellular polymeric matrix, may be detected from the stages of local infection and be associated with an increase in the number and virulence of microbial species. Thus, biofilms present in chronic wounds should be treated with appropriate cleaning agents (see dressings classification further below).^10,22

The formation of an exudate is part of normal wound healing, providing a moist wound environment for the proliferation of cells and assisting with the migration and support for the removal of devitalised tissue (autolysis).¹² When this occurs in excess, it increases the risk for infection, friction damage, maceration of surrounding tissue and an increase in wound size with delayed healing. It is therefore important to note the changes in the exudate consistency (serous, fibrinous, purulent, haemopurulent and haemorrhagic).¹²

For the edges to advance (migration of the epidermal cells from the margins across the wound bed), all other factors from the TIME enabler should be optimised. A non-advancing edge may reflect local infection as with undermining, rolling of the edges and pockets in the wound bed.¹²

The peri-wound tissue is also assessed regarding maceration (reflecting the excess of exudate), skin integrity (erosions, skin-stripping), induration, oedema, erythema/cellulitis/folliculitis, callous, xerosis, atopic eczema and hyperkeratosis and should be addressed in the treatment plan.^12,20

The DIME framework (Figure 2^15,24) incorporates the same principles of TIME, adding concepts regarding healability of wounds and the need to address the cause and other factors related to wound management into the enabler; D stands for debridement (surgical, sharp, autolytic, enzymatic, larval or biological and mechanical), I for inflammation/infection, M for moisture and E for edge.^15,24

The frameworks for WBP are tools to be used within the context of the holistic assessment of the patient. Patients need to understand the treatment plan and be involved with the treatment of the underlying cause of the wound for the wound management to be successful.¹² A holistic approach should include the assessment of the patient’s general health condition, nutritional status, lifestyle habits, current medications as well as the social, economic and psychological factors that may influence wound healing.^11,16

Wounds must be assessed and documented in terms of the type of wound, location in the body, size and shape with measurements of length, width and depth, amount of exudate, presence of odour/devitalised tissue/signs of inflammation or infection, level of pain, duration and any previous treatment done on the wound. Hence the use of measurement tools such as tape measurements, tracing paper or photography is important to document the progression of treatment.^16,25

Once the wound bed is assessed, the choice for the dressing will become an easier task (Figure 3¹³).

The treatment plan can be determined as per the WBP framework and should be reassessed at regular intervals. If after 2 weeks of treatment, there are minimal changes in the measurements of the wound in comparison with the initial measurements (edge effect), or if the wound bed shows changes in the type of tissue, levels of exudate/moisture, subtle or classic signs of local infection, non-advancing edges or new wound breakdown, then one can modify or change the treatment plan accordingly.^12,16,17,25

At any particular time in the assessment of any wound, clinicians should keep in mind that the wound status is an evolving process and adapt their choice of dressings accordingly. There is no single perfect dressing in the market that can be used for all stages of the wound healing process until the complete closure of the wound.

An ideal dressing should have the following characteristics: be easy to apply, safe to be removed without causing skin damage or pain; be cost-effective, stay intact for longer periods, avoid the need for frequent changes; conform to the wound bed/anatomical location, prevent leakage and suit the level of exudate; absorb odour when indicated, control bacterial proliferation and not cause allergic reactions.^20,25,26

Certain dressings are classified in South Africa as non-invasive medical devices and not medication and some of the advanced dressings need to be prescribed by a physician. The South African Health Products Regulatory Authority (SAHPRA) published in 2014 (updated in 2019), the guidelines for the licensing of manufacturers, distributors and wholesalers, with the registration of medical devices both non-invasive and invasive.²⁷ Dressings are classified according to rules and classes depending on what they contain:

The guidelines aim to maintain the safety, quality and performance of those classified as medical devices; the classification may differ from other countries.²⁷

The Wound Healing Association of Southern Africa (WHASA) has published and updated its classification of wound dressings regularly since its conception, because of the addition of new dressings in the South African market.^16,28 Choosing a particular dressing is a daunting task for the clinician who is not trained in wound management, as some products are listed in more than one category within the classification and the list of dressings available is continually expanding. The latest versions of the classification follow the structure of the WBP framework to facilitate the clinician when faced with new products launched in the market (Figure 4^12,24).

When an adequate treatment plan is in place, a healable wound should be 30% (20% – 40%) smaller by week four, to heal by week six.^15,24,26 Some wounds may become stalled or hard to heal and will need reassessment and adaptation to the initial treatment plan. Adjuvant therapies may be needed to advance the edges of the wound, such as biologic agents, negative pressure wound therapy (NPWT), skin substitutes and even closure by skin grafting or flaps. A referral to a multidisciplinary wound care team should be taken into consideration early in the management of wounds that are not progressing to healing.¹⁷