Expert opinion article.
Section 1. The DNA of Wound Hygiene
In the first consensus document published in 2020, the panel suggested that healthcare professionals (HCPs) involved in wound care practice move away from the term “chronic wounds” and instead begin using “difficult-to-heal wounds.” This call for a change in terminology is driven by two factors: recognizing that any wound, regardless of its type or etiology, can be difficult to heal; and rethinking these wounds through language that reflects the idea that barriers to healing can be overcome. Therefore, the panel reiterates that “difficult-to-heal” will be the terminology and wound type referred to in this document.
Hard-to-heal wounds: the value of waiting
It is now estimated that 2–6% of the global population live with wounds, and this figure is expected to increase as the population aged 65 and older — those most affected by difficult-to-heal wounds — grows, adding an additional 50+ million people by 2050. The cost of caring for people living with wounds extends up to 60 billion USD per year in the United States alone, and accounts for 2–4% (and rising) of healthcare expenditures across Europe. Additional concerns include high rates of antibiotic use contributing to antibiotic resistance; disproportionate use of nursing time; and the negative impact on people’s quality of life, including pain, restricted mobility, and psychological effects associated with living with wounds.
Section 2. Development of the concept of wound hygiene
A hard-to-heal wound remains difficult to treat until it is fully healed. This does not mean that the wounds are impossible to heal; rather, it refers to conditions that make healing more challenging. Healing is always possible and can result in wound regression, and in some cases, even full recovery. Therefore, it is crucial for healthcare professionals (HCPs) to monitor the progression of wound healing, implement strategies to accelerate it, and ensure closure is achieved. In particular, biofilm poses a serious threat to wound healing due to its rapid formation and reformation. As a result, a wound that shows exudate, slough, and an increase in size by the third day can already be classified as difficult-to-heal.¹ The concept of Wound Hygiene is based on the understanding that all difficult-to-heal wounds contain some level of biofilm, and Wound Hygiene represents an effective anti-biofilm approach that should be applied at every dressing change, at every stage of tissue development, until the wound is completely healed.
Wound healing and wound hygiene
All wounds (especially those that are hard-to-heal) will benefit from Wound Hygiene. Since biofilm is likely to be present at every stage of the healing process, Wound Hygiene should be initiated at the first presentation and then continued at every dressing change until full healing occurs. When visually assessing wound progression and healing, the type and color of tissue are often considered. There is a generally accepted “healing trajectory” consisting of four tissue types: necrotic or slough tissue, granulation tissue, and epithelializing tissue. However, this progression is rarely a linear process. In fact, many hard-to-heal wounds become “stalled” in an uncharacterized tissue type (although they may appear similar to granulating wounds) and struggle to transition to the next stage. This is often associated with the presence of biofilm; therefore, applying Wound Hygiene is particularly important for wounds with such characteristics. To address this issue, the panel suggests adding a fifth tissue type by distinguishing between unhealthy granulation tissue and healthy granulation tissue. Dead tissue usually results from a lack of blood supply to the tissues (ischemia) and can also occur due to infection in the wound bed. It typically appears black or brown in color, with either a hard/dry/leathery or soft/moist texture, and may be firmly or loosely attached to the wound bed. It should be differentiated from hematoma, dry scabs, or serous crusts. This tissue may also be referred to as “devitalized.”
Why biofilm is a major obstacle
It is currently known that biofilm is present in 78% of hard-to-heal wounds, although it is invisible to the naked eye (often <100 μm in size), can reform within 24 hours, and contributes to chronicity. Delayed healing, where biofilm is assumed to be present, is therefore a significant contributing factor in every wound. Although biofilm is primarily located on the wound surface, it can also accumulate in deeper tissues, distributed both between and within wound layers. Furthermore, any open wound may be colonized by opportunistic pathogens without discrimination between “healthy” and “unhealthy” appearing tissues. Studies have shown that biofilm can be present in granulation tissue, even when a wound appears to be progressing towards healing. In addition, hard-to-heal wounds can regress, and therefore should always be treated as difficult-to-heal until closure is achieved. This practice is also applied in the United Kingdom in the classification of pressure ulcers (PUs), where reverse staging is avoided—for example, during healing, a Stage 4 PU is not documented as Stage 3, 2, or 1, but rather as a “healing Stage 4 PU.” This is because biofilm can rapidly reform in any tissue, leading to regression of wound healing progress. As such, Wound Hygiene should be applied as early as possible, at every stage, until complete healing occurs. However, biofilm is not the only challenge in wound healing. Patient-related factors, including medical and psychosocial conditions, may also contribute to the persistence of biofilm (see Box 1). The panel suggests that biofilm may be the factor that pushes a wound into a hard-to-heal state, creating a cycle that must be broken through appropriate patient management, addressing underlying conditions, and implementing Wound Hygiene to combat biofilm.