Patients who are immobile endure prolonged bodyweight‐related compressive, tensional and shear loads at their body‐support contact areas that over time may lead to the onset of pressure ulcers (PUs). Approximately, one‐third of the common sacral PUs are severe and classified as category 3 or 4. If a PU has occurred, off‐loading is the basic, commonly accepted clinical intervention; however, in many situations, complete off‐loading of sacral PUs is not possible. Minimising the exposure of wounds and their surroundings to elevated mechanical loads is crucial for healing. Accordingly, in the present study, we aimed to investigate the biomechanical effects of the structural and mechanical properties of different treatment dressings on stresses in soft tissues surrounding a non‐offloaded sacral PU in a supine patient. Using a novel three‐dimensional anatomically realistic finite element modelling framework, we have compared performances of three dressing designs: (a) The Mepilex Border Sacrum (MBS) multilayer anisotropic silicone foam dressing (Mölnlycke Health Care), (b) an isotropic stiff dressing, and (c) an isotropic flexible dressing. Using our newly developed protective efficacy index (PEI) and aggravation index (AI) for assessing prophylactic and treatment dressings, we identified the anisotropic stiffness feature of the MBS dressing as a key design element.

No abstract

The sacral region is the most common site for pressure injuries (PIs) associated with lying in bed, and such sacral PIs often commence as deep tissue injuries (DTIs) that later present as open wounds. In complex patients, diabetes is common. Because, among other factors, diabetes affects connective tissue stiffness properties, making these tissues less able to dissipate mechanical loads through physiological deformations, diabetes is an additional biomechanical risk factor for PIs and DTIs. A preventive measure with established successful clinical outcomes is the use of sacral prophylactic dressings. The objective of this study has been to expand our previous work regarding the modes of action and biomechanical efficacy of prophylactic dressings in protecting the soft tissues adjacent to the sacrum by specifically examining the role of a directional stiffness preference (anisotropy) of the dressing while further accounting for diabetic tissue conditions. Multiple three-dimensional anatomically detailed finite element (FE) model variants representing diabetic tissue conditions were used, and tissue loading state data were compared with healthy tissue simulations. We specifically compared soft tissue exposures to elevated internal shear stresses and strain energy densities (SED) near the sacrum during supine weight bearing on a standard (foam) hospital mattress without a dressing, with a prophylactic dressing lacking directional stiffness preferences and with an anisotropic dressing. Our results have clearly shown that an anisotropic dressing design reduces the peak tissue stresses and exposure to sustained tissue deformations in both healthy and diabetic cases. The present study provides additional important insights regarding the optimal structural and material design of prophylactic dressings, which in turn, informs clinicians and decision makers regarding beneficial features.

Pressure ulcers (PUs) are one of the most prevalent adverse events in acute and chronic care. The root aetiological cause of PUs is sustained cell and tissue deformations, which triggers a synergistic tissue damage cascade that accelerates over relatively short time periods. Changes in skin microclimate conditions are known to indirectly contribute to PU‐risk levels or to exacerbation of existing wounds. It is therefore surprising that information concerning heat accumulation under dressings is poor. Here, we aimed to investigate the effects of dressings on the microclimate of weight‐bearing buttocks skin in 1‐hour supine lying sessions. Using a novel and originally developed experimental‐computational approach, we compared the combined influence of the mechanical and thermal properties of a polymeric membrane dressing (PolyMem, Ferris Mfg. Corp., Fort Worth, TX) on skin microclimate under and near the dressings with those of a standard placebo foam dressing. We specifically identified the thermal conductivity properties of dressings as being highly important in the context of protective dressing performances, given its association with potential heat accumulation under dressings. Accordingly, this article highlights, for the first time in the literature, the relevance of thermal properties of a dressing in effectively mitigating the risk of developing PUs or aggravating an injury, and offers a systematic, methodological bioengineering process for assessing the thermal performances of dressings.

The sequence of events described here demonstrates the difficulty in diagnosis and management of TB in this age group. Transmission of TB in NICU and PICUs is unusual but can occur, and calls for a systematic approach to investigation of the exposed infants, family members and health care providers.