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 effect of Ringer's solution within a dressing to elicit pain relief.

Clinical studies suggest that dressings containing Ringer's solution, such as the TenderWet and HydroClean families, provide relief from wound pain. This report reviews the available evidence and possible mechanisms for the relief of wound pain by these dressings. The ability of dressings containing Ringer's solution to provide pain relief is likely to be through providing a moist environment that is favourable for wound healing; furthermore, the dressing augments the protective barrier function by having additional fluid under the dressing, which covers exposed nerve endings and protects against friction damage. Ringer's solution will have a dilution effect and an influence on the pH of exudate. Diluting cytokines within the exudate would be expected to decrease inflammation in chronic wounds and reduce the influence of caustic components such as matrix metalloproteases (MMPs). Altering the pH of the wound bed could inactivate proteins and glycoproteins implicated in the pain response such as MMPs and sodium and calcium channels. The moist environment may also be better at recruiting leukocytes that release natural painkillers at areas of injury. These mechanisms are likely to act in combination to explain why dressings containing Ringer's solution can have analgesic effects.

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.

Wound healing and hyper-hydration: a counterintuitive model.

Winter's seminal work in the 1960s relating to providing an optimal level of moisture to aid wound healing (granulation and re-epithelialisation) has been the single most effective advance in wound care over many decades. As such the development of advanced wound dressings that manage the fluidic wound environment have provided significant benefits in terms of healing to both patient and clinician. Although moist wound healing provides the guiding management principle, confusion may arise between what is deemed to be an adequate level of tissue hydration and the risk of developing maceration. In addition, the counter-intuitive model 'hyper-hydration' of tissue appears to frustrate the moist wound healing approach and advocate a course of intervention whereby tissue is hydrated beyond what is a normally acceptable therapeutic level. This paper discusses tissue hydration, the cause and effect of maceration and distinguishes these from hyper-hydration of tissue. The rationale is to provide the clinician with a knowledge base that allows optimisation of treatment and outcomes and explains the reasoning behind wound healing using hyper-hydration. Declaration of interest: K. Cutting is a Clinical Research Consultant to the medical device and biotechnology industry. M. Rippon is Visiting Clinical Research Fellow, University of Huddersfield and K. Ousey provides consultancy for a range of companies through the University of Huddersfield including consultancy services for Paul Hartmann Ltd on HydroTherapy products.

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.

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.

Ultrasound assessment of skin and wound tissue: comparison with histology.

BACKGROUND/AIMS: Ultrasound is a valuable technique in dermatological assessment as it is non-invasive. This is particularly attractive for monitoring and evaluating wound healing. However, there is a limited literature on the use of ultrasound in monitoring wound healing. METHODS: In this study, the structures of skin (human and porcine) and healing wounds (porcine) were visualised using ultrasound (20 MHz) and compared with histology from the same site. Measurements of various features were undertaken using both ultrasound and histometric techniques and the results from each compared. Hydroxyproline levels were also measured and correlated with ultrasound measurement of granulation tissue. RESULTS: The echogenic characteristics of tissues are described. There was excellent correlation (r=0.96, P > 0.0001) between the ultrasound measurements and histology for porcine and human cadaver measurements. Ultrasound and histology measurements of acute porcine wounds also correlated well (r=0.96,P<0.0001). Comparison of hydroxyproline analysis with ultrasound measurements of fibrous granulation tissue (r=0.82,P > 0.001) indicates that ultrasound may be used to visualise accumulation of this tissue in wounds. CONCLUSIONS: Ultrasonography has been shown to be a useful, reliable, quantifiable technique for the assessment of wound healing.

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.