How Should Clinical Wound Care and Management Translate to Effective Engineering Standard Testing Requirements from Foam Dressings? Mapping the Existing Gaps and Needs

Alternating Current Electrospinning of Polycaprolactone/Chitosan Nanofibers for Wound Healing Applications

Traditional wound dressings have not been able to satisfy the needs of the regenerative medicine biomedical area. With the aim of improving tissue regeneration, nanofiber-based wound dressings fabricated by electrospinning (ES) processes have emerged as a powerful approach. Nowadays, nanofiber-based bioactive dressings are mainly developed with a combination of natural and synthetic polymers, such as polycaprolactone (PCL) and chitosan (CHI). Accordingly, herein, PCL/CHI nanofibers have been developed with varying PCL:CHI weight ratios (9:1, 8:2 and 7:3) or CHI viscosities (20, 100 and 600 mPa·s) using a novel alternating current ES (ACES) process. Such nanofibers were thoroughly characterized by determining physicochemical and nanomechanical properties, along with wettability, absorption capacity and hydrolytic plus enzymatic stability. Furthermore, PCL/CHI nanofiber biological safety was validated in terms of cytocompatibility and hemocompatibility (hemolysis < 2%), in addition to a notable antibacterial performance (bacterial reductions of 99.90% for S. aureus and 99.91% for P. aeruginosa). Lastly, the enhanced wound healing activity of PCL/CHI nanofibers was confirmed thanks to their ability to remarkably promote cell proliferation, which make them ideal candidates for long-term applications such as wound dressings.

The importance of the simulated wound fluid composition and properties in the determination of the fluid handling performance of wound dressings

Effective fluid handling by wound dressings is crucial in the management of exuding wounds through maintaining a clean, moist environment, facilitating healing by removing excess exudate and promoting tissue regeneration. In this context, the availability of reliable and clinically relevant standardised testing methods for wound dressings are critical for informed decision making by clinicians, healthcare administrators, regulatory/reimbursement bodies and product developers. The widely used standard EN 13726 specifies the use of Solution A, an aqueous protein-free salt solution, for determining fluid-handling capacity (FHC). However, a simulated wound fluid (SWF) with a more complex composition, resembling the protein, salt, and buffer concentrations found in real-world clinical exudate, would provide a more clinically relevant dressing performance assessment. This study compared selected physicochemical parameters of Solution A, an alternative, novel simulated wound fluid (SWF A), and a benchmark reference serum-containing solution (SCS) simulating chronic wound exudate. Additionally, FHC values for eight advanced bordered and non-bordered foam dressings were determined for all three test fluids, following EN 13726. Our findings demonstrate a close resemblance between SWF A and SCS. This study highlights the critical importance of selecting a physiochemically appropriate test fluid for accurate FHC testing resulting in clinically meaningful evaluation of dressing performance.

Strategies in surface engineering for the regulation of microclimates in skin-medical product interactions

There is a growing number of personal healthcare devices that are in prolonged contact with the skin. The functionality of these products is linked to the interface formed by the contact between the medical apparatus and the skin. The interface can be characterised by its topology, compliance, and moisture and thermal regulating capabilities. Many devices are, however, described to have suboptimal and occlusive contacts, resulting in physiological unfavourable microclimates at the interface. The resulting poor management of moisture and temperature can impact the functionality and utility of the device and, in severe cases, lead to physical harm to the user. Being able to control the microclimate is therefore expected to limit medical-device related injuries and prevent associated skin complications. Surface engineering can modify and potentially enhance the regulation of the microclimate factors surrounding the interface between a product's surface and the skin. This review provides an overview of potential engineering solutions considering the needs for, and influences on, regulation of temperature and moisture by considering the skin-medical device interface as a system. These findings serve as a platform for the anticipated progress in the role of surface engineering for skin-device microclimate regulation.

Fluid handling by foam wound dressings: From engineering theory to advanced laboratory performance evaluations

This article describes the contemporary bioengineering theory and practice of evaluating the fluid handling performance of foam-based dressings, with focus on the important and clinically relevant engineering structure-function relationships and on advanced laboratory testing methods for pre-clinical quantitative assessments of this common type of wound dressings. The effects of key wound dressing material-related and treatment-related physical factors on the absorbency and overall fluid handling of foam-based dressings are thoroughly and quantitively analysed. Discussions include exudate viscosity and temperature, action of mechanical forces and the dressing microstructure and associated interactions. Based on this comprehensive review, we propose a newly developed testing method, experimental metrics and clinical benchmarks that are clinically relevant and can set the standard for robust fluid handling performance evaluations. The purpose of this evaluative framework is to translate the physical characteristics and performance determinants of a foam dressing into achievable best clinical outcomes. These guiding principles are key to distinguishing desirable properties of a dressing that contribute to optimal performance in clinical settings.

Research Roundup

Aysha Mendes provides a synopsis and brief review of a selection of recently published research articles that are of interest to community nurses, highlighting key points to keep you up to date; a full reference is provided for those who wish to read the research in more detail.

A robotic venous leg ulcer system reveals the benefits of negative pressure wound therapy in effective fluid handling

We applied a market-leading, single-use negative pressure wound therapy device to a robotic venous leg ulcer system and compared its fluid handling performance with that of standard of care, superabsorbent and foam dressings and compression therapy. For each tested product, we determined a metrics of retained, residual, evaporated and (potential) leaked fluid shares, for three exudate flow regimes representing different possible clinically relevant scenarios. The single-use negative pressure wound therapy system under investigation emerged as the leading treatment option in the aspects of adequate fluid handling and consistent delivery of therapeutic-level wound-bed pressures. The superabsorbent dressing performed reasonably in fluid handling (resulting in some pooling but no leakage), however, it quickly caused excessive wound-bed pressures due to swelling, after less than a day of simulated use. The foam dressing exhibited the poorest fluid handling performance, that is, pooling in the wound-bed as well as occasional leakage, indicating potential inflammation and peri-wound skin maceration risks under real-world clinical use conditions. These laboratory findings highlight the importance of advanced robotic technology as contemporary means to simulate patient and wound behaviours and inform selection of wound care technologies and products, in ways that are impossible to achieve if relying solely on clinical trials and experience.

The development of a core outcome set for clinical effectiveness studies of bordered foam dressings in the treatment of complex wounds

AIM

The aim of this project was to develop a core outcome set (COS) for clinical effectiveness studies of bordered foam dressings in the treatment of complex wounds.

METHODS

The research project followed the Core Outcome Measures in Effectiveness Trials (COMET) initiative and consisted of two phases. The first phase prepared the background and process, while the second phase had three steps: outcome list generation via systematic review and qualitative study, Delphi consensus study, and consensus meeting. The study has been registered in the Core Outcome Measures in Effectiveness Trials database.

RESULTS

The systematic review resulted in 82 outcomes and 20 additional outcomes were obtained during the interviews. After refinement, 111 panellists from 23 countries rated a list of 51 outcomes. In the following consensus meeting, six outcomes were prioritized to be included in the core outcome set. After the consensus meeting, a patient-reported outcome was added to the core outcome set.

CONCLUSION

The COS for evaluating the effectiveness of bordered foam dressings in treating complex wounds includes 7 outcomes: "ability to stay in place", "leakage", "pain", "dressing related periwound skin changes", "change in wound size over time", and "overall satisfaction". These identified outcomes are correlated with contemporary bioengineering testing and evaluation methods for dressing performance, which underpins the need for a close multidisciplinary collaboration to advance the field of wound dressings. The outcome 'overall satisfaction' reflects the impact of complex wounds and their treatment on a patient's daily life. The use of these outcomes is recommended to improve data synthesis and promote evidence-based practice. Future developments in COS development involve creating measurement instruments and relevant endpoints for these outcomes.

Differences in prophylactic performance across wound dressing types used to protect from device-related pressure ulcers caused by a continuous positive airway pressure mask

Prolonged use of continuous positive airway pressure masks, as often required for non-invasive ventilation, involves a risk for facial tissue breakdown due to the sustained deformations caused by tightening of the stiff mask surfaces to the head and the moist environment. The risk of developing mask-related facial injuries can be reduced through suitable cushioning materials placed at the skin-mask interfaces to spread the localised contact forces and disperse the surface and internal tissue stresses. Using an integrated experimental-computational approach, we compared the biomechanical protective performance of three popular foam-based wound dressings to that of a market-lead hydrocolloid dressing when applied to protect the facial skin under a mask. We measured the compressive stiffness properties of the four commercial dressing types in dry and moist conditions, and then fed those to an anatomically realistic finite element model of an adult male head, with an applied simulated mask. Through this process, we calculated the protective efficacy index of each dressing type, indicating the relative contribution of the specified dressing to alleviating facial soft tissue loads with respect to the no-dressing case. The foam-based dressings generally performed substantially better than the hydrocolloid, but foam dressings were also demonstrated to vary by their protective performance.

Mechanical and contact characteristics of foam materials within wound dressings: Theoretical and practical considerations in treatment

In the treatment of acute and chronic wounds, the clinical performance of a given foam-based dressing, and, ultimately, the wound healing and cost of care outcomes are strongly influenced by the mechanical performance of the foam material/s within that dressing. Most aspects of the mechanical performance of foam materials, for example, their stiffness, frictional properties, conformability, swelling characteristics and durability, and the overall mechanical protection provided by a foam-based dressing to a wound strongly depend on the microstructure of the foam components, particularly on their microtopography, density and porosity. This article, therefore, provides, for the first time, a comprehensive, self-inclusive compilation of clinically relevant theoretical and practical considerations, based on published analytical and experimental research as well as clinical experience related to the mechanical performance of foams in foam-based wound dressings. The current bioengineering information is useful for establishing understanding of the importance of mechanical properties of foams in foam-based dressings among clinicians and researchers in industry and academia, and other potential stakeholders in the wound care field, for example, regulators and buyers. This information is also particularly important for the development of standardised test methods for the evaluation of foam-based wound dressings and resulting standard mechanical performance metrics for these dressings.

Fluid handling performance of wound dressings tested in a robotic venous leg ulcer system under compression therapy

We designed, developed, built, and utilised a robotic system of a leg with two venous leg ulcers for testing the fluid handling performance of three wound dressing types. The results showed that a foam-based dressing technology is inferior in fluid handling performance when applied to an exuding venous leg ulcer, such that the dressing needs to manage the exudate in a vertical configuration with respect to the ground, that is, so that gravity pulls the exudate to concentrate in a small region at the bottom of the dressing. Moreover, wound dressings containing superabsorbent polymers do not necessarily function equally in fluid handling for venous leg ulcer scenarios, as the extreme requirements from the dressing (to manage the viscous fluid of a vertical and typically highly-exuding wound) appear to distinguish between optimal and suboptimal product performances despite that the tested products contain a superabsorbent, theoretically lumping them together to belong to a so-called 'superabsorbent dressing category'. In other words, it is a false premise to categorise products from different manufacturers into families based on material contents, and then assume that their laboratory or clinical performance is equal, so that from this point they can be judged solely on the basis of price.