Soft silicone multi-layer dressings are commonly used for pressure ulcer (pressure injury) prevention, yet their effectiveness varies based on design, construct, and material properties. This study evaluated the protective efficacy of a new multi-layer dressing, ALLEVYN COMPLETE CARE (ACC, Smith & Nephew Limited), which incorporates an advanced structure facilitating the dissipation of shear forces through internal layer-on-layer frictional sliding within the dressing. Using a combination of experimental frictional energy absorber effectiveness (FEAE) testing and computational finite element modelling, we quantified the capacity of this dressing to mitigate strain and stress concentrations in the soft tissues of the supported posterior heel. The dressing demonstrated considerable frictional sliding between its adjacent layers, resulting in FEAE = 93% under simulated, clinically relevant usage conditions. This was associated with the dissipation of shear forces and alleviation of strain/stress concentrations in the skin and underlying soft tissues below the dressing. The dressing completely eliminated the stress and strain peaks at the top quartiles of the strain/stress domain (with reference to a no-dressing case). This work provided valuable insights into advanced testing methods and beneficial design principles for pressure ulcer prevention dressings. Earlier investigations concluded that a previous-generation ALLEVYN LIFE dressing achieved high levels of FEAE and thus provided protection. Our findings here establish that the next-generation dressing, ACC, demonstrates even greater protective capacity.
The classification of wound care products as form-stable dressings remains challenging due to the lack of objective and quantitative, material-science-based criteria. This study introduces a rheological testing framework to determine form stability of wound dressing materials. Using dynamic, oscillatory shear rheology, we evaluated the viscoelastic properties and responses of two tube-dispensed model dressings and compared them to those of honey, a high-viscosity liquid used in wound ointments. Measurements of the material storage modulus, loss modulus and phase angle demonstrated that both model dressings exhibit predominantly solid-like responses, confirming their classification as form-stable wound dressings despite being applied from a tube. The notably low phase angles of these dressings indicate structural integrity, which is essential for the mechanical protection of wounds; honey exhibited a liquid response and a high phase angle, without structural integrity. The reported laboratory method and findings support the implementation of rheological classification as a standardised, objective and quantitative approach for wound care product categorisation, independent of the packaging or application mode. Importantly, this study establishes a foundation for a material-science-driven classification framework, with implications for informed clinical decision-making and reimbursement policies.
Negative pressure wound therapy is used often in the management of surgical incisions, chronic wounds and subacute lesions, and there are numerous publications discussing its clinical application and outcomes. However, whilst clinical use and associated literature have expanded since these systems became commercially available in the 90s, important research and discussion around the mode of action have waned, leading to a deficit in the understanding of how this important therapy influences healing. Further, much research and many publications are predominantly reflective, discussing early theorem, some of which have been proven incorrect, or at least not fully resolved leading to misunderstandings as to how the therapy works, thus potentially denying the clinician the opportunity to optimise use towards improved clinical and economic outcomes. In this narrative review, we discuss established beliefs and challenges to same where appropriate and introduce important new research that addresses the manner in which mechanical strain energy (i.e., deformations) is transferred to tissue and how this influences biological response and healing. In addition, we assess and discuss the effect of different negative pressure dressing formats, how they influence the mode of action and how this understanding can lead to more efficient and effective use and clinical economic outcomes.
Pressure ulcers including heel ulcers remain a global healthcare concern. This study comprehensively evaluates the biomechanical effectiveness of the market-popular ALLEVYN® LIFE multilayer dressing in preventing heel ulcers. It focuses on the contribution of the frictional sliding occurring between the non-bonded, fully independent layers of this dressing type when the dressing is protecting the body from friction and shear. The layer-on-layer sliding phenomenon, which this dressing design enables, named here the frictional energy absorber effectiveness (FEAE), absorbs approximately 30%–45% of the mechanical energy resulting from the foot weight, friction and shear acting to distort soft tissues in a supine position, thereby reducing the risk of heel ulcers. Introducing the novel theoretical FEAE formulation, new laboratory methods to quantify the FEAE and a review of relevant clinical studies, this research underlines the importance of the FEAE in protecting the heels of at-risk patients. The work builds on a decade of research published by our group in analysing and evaluating dressing designs for pressure ulcer prevention and will be useful for clinicians, manufacturers, regulators and reimbursing bodies in assessing the effectiveness of dressings indicated or considered for prophylactic use.
We investigated the inflammatory (IL-1 alpha) and thermal (infrared thermography) reactions of healthy sacral skin to sustained, irritating mechanical loading. We further acquired digital photographs of the irritated skin (at the visible light domain) to assess whether infrared imaging is advantageous. For clinical context, the skin status was monitored under a polymeric membrane dressing known to modulate the inflammatory skin response. The IL-1 alpha and infrared thermography measurements were consistent in representing the skin status after 40 min of continuous irritation. Infrared thermography overpowered conventional digital photography as a contactless optical method for image processing inputs, by revealing skin irritation trends that were undetectable through digital photography in the visual light, not even with the aid of advanced image processing. The polymeric membrane dressings were shown to offer prophylactic benefits over simple polyurethane foam in the aspects of inflammation reduction and microclimate management. We also concluded that infrared thermography is a feasible method for monitoring the skin health status and the risk for pressure ulcers, as it avoids the complexity of biological marker studies and empowers visual skin assessments or digital photography of skin, both of which were shown to be insufficient for detecting the inflammatory skin status.
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.