Protocols in wound healing: Evidence-based or mere rituals?

Abstract

Any wound care protocol, whether acute or chronic, begins with the recommendation for wound cleansing, which is considered as a cornerstone of the treatment. In addition, some papers have been published comparing different products (tap water, saline, soap, antimicrobials) and cleansing techniques (different irrigation pressures).¹ However, what is the available evidence that all wounds need cleansing?² Moreover, could not a ritual swabbing or scrubbing be detrimental to the neoformed tissue?³ These same questions could be asked with debridement, which is also often included as a mandatory step in every dressing change. In fact, in the case of venous ulcers, except in certain recalcitrant sloughy wounds,⁴ it is not clear that debridement, in a general way, accelerates healing. In other words, just because we get a venous leg ulcer with less sloughy tissue at each dressing does not mean that we will accelerate healing, as it was shown with larval therapy.⁵ In addition, sharp debridement will have no benefit in cases of white atrophy and will produce pain, and in pyoderma gangrenosum or arteriolosclerotic ulcers, it may worsen the wound. In addition, a recent pilot study shows that, contrary to the traditional belief that slough is a devitalised tissue that delays healing, there are functional proteins in this tissue that can promote healing.⁶

The frequency of dressing changes is another aspect that has not been studied, but in many cases, it is done ritually two to three times a week, or even daily. Thanks to the impossibility of making wound dressing changes during the covid pandemic, some of us realized that not touching the wound for 1, 2, 3 or even 4 weeks was not only not harmful to venous leg ulcers, but even allowed their complete epithelialization.

We cannot make protocols that include chronic wounds in general, because wounds that are progressing well should be managed differently.⁷

On the one hand, each dressing is an opportunity to promote, with cleansing and debridement, the removal of whatever is hindering healing (excess exudate with pro-inflammatory cytokines, non-viable tissue, bacterial load), which is essential in dirty or infected wounds and in cases of resistant biofilm. On the other hand, any manipulation of the wound bed will have an impact on the cells and growth factors that are promoting wound closure, and may induce inflammation² that, in those wounds with a good progression, could impede wound healing. Wound exudate, especially in acute wounds and wounds that are having a good evolution, is a source of cells and growth factors that promote healing. Additionally interactions between commensal microbiota and the multiple cell types involved in cutaneous wound healing have been shown to regulate the immune response and promote barrier restoration.⁸ Consequently, in acute non-complicated wounds and those chronic wounds that present a good evolution, it would be wise not to interfere with the created microenvironment that is favouring healing. It is going to be extremely relevant according to new research focusing on cells and proteins whose presence in the exudate would be able to define and differentiate it as “toxic” or “physiological”.^{7, 9} As wounds with a “toxic” wound fluid should probably be better cleansed and debrided, those with a “physiological” wound fluid should not. This reflection leaves open the question of what would be the most appropriate debridement, and ultimately, all these questions should be better investigated in randomized controlled trials.

For this maximum spacing of dressing changes, optimal treatment of the cause of the wound is essential, in the case of venous ulceration, with compression therapy, endovenous ablation or surgery, exercise and leg elevation during rest. In fact, it is this aetiological treatment that will reduce exudate, not the dressing selected.¹⁰ However, in the last decades, professionals have focused a lot on the importance of moist wound healing dressings since Winter's famous, but little read article,¹¹ which included only 12 acute wounds on the back of two pigs. The results of this letter to the editor highlight that in the first 3 days, the epithelialization rate was twice higher in the wounds covered with polyurethane film in comparison with those wounds left open air, but, surprisingly, from day 7, there is no difference between both groups.

Since then, despite the generalization of the concept of moist wound healing following the higher rate of initial epithelialization in Winter's study, little evidence has been generated in chronic wounds.¹² Most clinical trials with dressings have been conducted on acute wounds (mainly graft donor site) and without significant differences between them, perhaps because these wounds will close in less than 3 weeks without needing any specific care. But the choice of alginate fibres allowed the dressing to be left in place without touching until complete epithelialization.^{13, 14}

The authors think that rather than talking about a “moist” environment, one should talk about an “optimal” environment, including scabs. We agree with Nelson¹⁵: “Since we have used scabs as a wound cover for thousands of years, we should try to improve their performance, rather than ignore the benefits of this very effective dressing”. Along these lines of simulating wound scabs would be the use of fibres (such as alginate fibres), which generate matrices that can remain in the wound for weeks, promoting underlying epithelialization, both in acute and chronic wounds, spacing out dressing changes. Additionally, it would make sense to add zinc oxide, which has already been shown to benefit wound healing in an old but well-designed study with leg ulcers.¹⁶

Zinc oxide has anti- inflammatory and antibacterial properties, promotes re-epithelialization and,¹⁷ consequently, has been shown to be beneficial in different inflammatory skin disorders.¹⁸ Zinc oxide is a combination routinely used by some of the authors, spacing dressings as much as possible and without cleansing or debridement of wounds that do not need it, with good results, even in hard-to-heal wounds treated with punch grafting.¹⁹

In addition to being beneficial for the wound, avoiding the pain and trauma involved in each dressing change is also an eco-responsible strategy. But the benefits of this strategy, so far, are only based on observation. Clinical trials are needed to break rituals and to be able to establish protocols with a real benefit for the wound and the person and more sustainable for the planet. And not to forget the benefit for healthcare professionals, especially nurses. Currently, there are multiple obstacles in the application of nursing care due to gaps in wound healing studies, variability in wound training, different care settings (primary care, specialized care) and the overwhelming number of dressing types. Undoubtedly, there is a need for rational simplification of wound care.²⁰

The authors declare no conflicts of interest.