The influence zone: a critical performance measure for negative pressure wound therapy systems

Revisiting negative pressure wound therapy from a mechanobiological perspective supported by clinical and pathological data

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.

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.

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.