A multicentre, clinical evaluation of a hydro-responsive wound dressing: the Glasgow experience

OBJECTIVE

Our aim was to assess the effectiveness of hydro-responsive wound dressing (HRWD) in debridement and wound bed preparation of a variety of acute and chronic wounds that presented with devitalised tissue needing removal so that healing may proceed.

METHOD

This was a non-comparative evaluation of acute and chronic wounds that required debridement as part of their normal treatment regimen. Clinicians recorded wound changes including a subjective assessment level of devitalised tissue and wound bed preparation, presence of pain, wound status (e.g., wound size) and periwound skin condition. Data was also collected from clinicians and patients to provide information on clinical performance of the dressing.

RESULTS

We recruited 100 patients with a variety of wound types into the study. Over 90% of the clinicians reported removal of devitalised tissue to enable a healing response in both chronic and acute wounds. Specifically, over the course of the evaluation period, levels of devitalised tissue (necrosis and slough) reduced from 85.5% to 26.3%, and this was accompanied by an increase in wound bed granulation from 12.0% to 33.7%. Correspondingly, there was a 40% reduction in wound area, hence a clinically relevant healing response was seen upon treatment with HRWD. It is also noteworthy that this patient population included a significant proportion of chronic wounds (51.4%) that showed no signs of wound progression within <4 weeks before study inclusion. Of these chronic wounds, 93% demonstrated wound progression upon treatment with HRWD. Despite reported pain levels being low pre- and post-dressing change, overall wound pain improved (reduced) in 48% of patients. Periwound skin condition showed a tendency towards improvement, and the fluid management capabilities of the HRWD was reported as good to excellent in the majority of cases. Wound infections were reduced by at least 60% over the evaluation period. A simple cost-effective analysis demonstrated significant savings using HRWD (£6.33) over current standard practice regimens of a four-step debridement process (£8.05), larval therapy (£306.39) and mechanical pad debridement (£11.46).

CONCLUSION

HRWD was well tolerated and was demonstrated to be an efficient debridement tool providing rapid, effective and pain free debridement in a variety of wound types.

The importance of hydration in wound healing: reinvigorating the clinical perspective

Balancing skin hydration levels is important as any disruption in skin integrity will result in disturbance of the dermal water balance. The discovery that a moist environment actively supports the healing response when compared with a dry environment highlights the importance of water and good hydration levels for optimal healing. The benefits of 'wet' or 'hyper-hydrated' wound healing appear similar to those offered by moist over a dry environment. This suggests that the presence of free water may not be detrimental to healing, but any adverse effects of wound fluid on tissues is more likely related to the biological components contained within chronic wound exudate, for example elevated protease levels. Appropriate dressings applied to wounds must not only be able to absorb the exudate, but also retain this excess fluid together with its protease solutes, while concurrently preventing desiccation. This is particularly important in the case of chronic wounds where peri-wound skin barrier properties are compromised and there is increased permeation across the injured skin. This review discusses the importance of appropriate levels of hydration in skin, with a particular focus on the need for optimal hydration levels for effective healing. Declaration of interest: This paper was supported by Paul Hartmann Ltd. The authors have provided consultative services to Paul Hartmann Ltd.

Adsorption of serum-derived proteins by primary dressings: implications for dressing adhesion to wounds

Using an in vitro immunolocalization technique, an exploratory study was carried out into the serum-derived protein adsorption capacity and the cell adherence of a traditional gauze dressing versus a new gelling fibre gauze dressing. We found that the traditional gauze dressing adsorbed protein more readily than the new dressing. The findings indicate that reduced binding of serum proteins to the surface of the gelling fibre dressing may help reduce the adherence characteristics for this type of dressing, minimising trauma and possibly reducing the acute pain experienced during dressing changes.

Application of an in vitro model to evaluate bioadhesion of fibroblasts and epithelial cells to two different dressings

The cellular component of a healing wound consists of many cell types and the environment in which these cells grow is important to the rate and quality of healing which can be influenced by the type of dressing used. The most commonly used dressings are traditional gauze-type dressings. In many cases these dressings may adhere to the wound surface, and subsequent removal is often traumatic, causing pain and tissue reinjury. Some modern gelling dressings have been developed to overcome this adherence problem. In order to evaluate in more detail cell-dressing interactions, an in vitro model has been developed utilising wound fibroblasts and epithelial cells. Quantitative evaluation of adherence of cells cultured with a traditional gauze or a new gelling dressing has been undertaken using radiolabel and manual counting techniques. Scanning electron microscopy has been used to visualise the cells adherent to dressings allowing evaluation of their adhesion-morphology. The results show differential attachment of cells to viscose and gelling fibres of the dressings; considerably reduced cell adhesion to the gelling fibre was evident, and it was apparent that cells adhered predominantly to the viscose component of the dressing. This model can be used to investigate and compare the adhesion of cells to different dressings and their components.

In vitro model(s) for the percutaneous delivery of active tissue repair agents

There is a need to evaluate the permeability of human ulcerated tissue and periulcer tissue in order to assess the possible treatment of such a localized pathological lesion with a topical therapy. In vitro percutaneous absorption studies were undertaken to evaluate an animal model that may mimic this clinical situation. Porcine skin from three anatomical sites, the ear, abdomen, and dorsum; ischaemic skin (porcine and guinea pig); porcine wounds; and human skin (including periulcer and ulcerated tissue) were investigated, utilizing both whole skin and dermal membranes. Dermal membranes were chosen as representative of ulcerated tissue, as there would be no epidermal barrier present, and the thickness of the dermal membrane was not expected to offer any diffusional resistance to topically applied active agents. A range of chemicals with differing physicochemical properties was investigated using a Franz type diffusion cell. For all tissues a permeability coefficient (kp with units of cm h-1) was measured, along with skin thickness and tissue partition coefficient measurements. Under these experimental conditions and for the range of compounds tested, the results suggest that porcine skin, whole skin, and dermal membranes should be considered as good representative in vitro models for the topical delivery of compounds to human skin and ulcerated tissue, respectively.