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Objective: To develop a robotic phantom system containing multiple simulated wound replicates to determine the synergy in fluid absorbency and retention (sorptivity) performances and the post-simulated-use mechanical durability of silver-containing gelling fiber primary dressings when used with a secondary dressing, as per clinical practice., Methods: Using a robotic system containing six identical wound simulators, the authors tested the sorptivity performances of the Exufiber Ag + (Mölnlycke Health Care, Gothenburg, Sweden) primary dressing (ExAg-polyvinyl alcohol [PVA]) against a market-leading comparator product, when used with a secondary foam dressing. The durability of the primary dressings after simulated use was further investigated through tensile mechanical testing., Results: The ExAg-PVA primary dressing delivered greater fluid amounts for absorbency and retention by the secondary foam dressing, approximately 2- and 1.5-fold more than the comparator dressing pair after 10 and 15 hours, respectively. The ExAg-PVA dressing was also substantially less sensitive to the direction of pulling forces and, accordingly, exhibited post-use mechanical strength that was approximately four and six times greater than that of the other primary dressing (when the latter dressing was tested out-of-alignment with its visible seams) after 10 and 15 hours, respectively., Conclusions: The dynamics of the sorptivity and fluid sharing between primary and secondary dressings and the effect of directional preference of strength of the primary dressings for adequate durability, resulting in safe post-use removals, have been described. The comparative quantification of these capabilities should help clinical and nonclinical decision-makers select dressings that best meet their patient needs., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: A continuing complication, pressure injuries are due to sustained mechanical loading and tissue deformations, which can then be exacerbated by additional intrinsic and extrinsic risk factors. Although support surfaces are designed to mitigate risk factors for pressure injuries, the presence of a turn and position device (TPD) between the patient and support surface may interfere with how support surfaces affect these risk factors., Objective: Report the use of the NPIAP's S3I standard test methods to characterize the performance of a support surface when used in conjunction with three different TPDs., Design: Laboratory testing compared three TPDs for Immersion, Envelopment, and Horizontal Stiffness in each of five surface combinations., Main Outcome Measure: Immersion test measures how far mannequin indenter immerses into surface. Envelopment test measures immersion and pressure distribution with hemispherical-indenter with mounted sensor rings. Horizontal Stiffness test measures the shear modulus of the support surface with epicondyle indenter., Main Results: For the specific TPDs tested here, the one with an adjustable integrated air bladder improved rather than compromised both the envelopment and the immersion of the support surface alone. Additionally, this TPD provided potential protection against sliding and the associated frictional shear forces., Conclusions: This paper describes how TPDs should perform in order to help establish which features are needed in a new medical device of this type. Laboratory testing demonstrates it is possible to improve performance of a support surface by applying a TPD as an add-on, thus relieving tissue deformation exposure through more effective pressure redistribution.

Results from large-scale randomized clinical trials support the application of prophylactic dressings to provide protection from body-weight force-induced deformations known to damage skin and underlying tissues, which often result in pressure injuries (pressure ulcers). This laboratory study using a new method for aging dressings in simulated use followed by tensile testing was conducted to further understand the protective effect of sacral prophylactic dressings (SPDs) in alleviating tissue deformations in the sacral region through the course of typical application. Specifically, four SPDs were exposed to a simulation of the clinical environment incorporating saline solution absorption, mechanical loading, and repetitive sliding-induced shear. After aging, the protective endurance of the SPDs was measured through tensile testing to determine their effectiveness against tissue-damaging forces over time.This study uses the concepts of axial stiffness, protective endurance, and elastic limit to describe more accurately the protective aspects of SPDs under dry and moist conditions and how they interact with the skin and underlying tissues over the life of the dressing. The authors propose two primary features in SPD effectiveness in preventing pressure injuries: high conformability (ie, low flexural stiffness) and protective endurance (the dressing's capacity to maintain biomechanical performance when moist).

It has been demonstrated that wound dressings provide a protective effect against pressure injuries. However, no method exists to measure either the life or performance of dressings used in prevention; testing dressings in a clinical setting or a research environment has typically been based on measuring its moisture absorption capacity. This article examines the changes that occur in the structural and mechanical properties of a prophylactic dressing based on conditions of use when wound exudate is not present.A clinically relevant method was developed to simulate the loading, friction-inducing shear, and moisture transpiration present in a typical hospitalization where a dressing is applied for prevention. Single-use dressings were tested using this method to evaluate their ability to protect patients from pressure injuries throughout the typical 5 to 7 days of use. Following this aging process, researchers measured the physical, structural, and mechanical changes in prophylactic dressings over time.This innovative method provides guidance for clinicians on dressing use and replacement intervals. For bioengineers, the method generates important empirical data for computer modeling of dressing performance, which can then reveal the consequences of changes in dressing structure and function on sustained tissue loads. It is the authors' hope to generate discussion about the creation of industry-wide standards for testing dressings to improve patient care.

This article is a review of the work conducted and published to date in employing computer finite element (FE) modeling for efficacy research of prophylactic dressings in the context of preventing pressure injuries. The authors strive to explain why FE modeling is essential in establishing the efficacy of prophylactic dressings, as it is in the development and evaluation of any other preventive intervention. In particular, FE modeling provides insights into the interactions between dressing structures and weight-bearing body tissues (including susceptible anatomical locations such as the sacrum and heels of supine patients). Modeling further facilitates reliable visualization and quantification of the mechanical loads that develop in superficial and deep tissues as a result of body weight or external forces based on known physical principles. The modeling then helps to determine how these tissue loads are mitigated using prophylactic dressings of different designs, structures, and material compositions and rate performances of existing or new products.All of the work published so far on modeling the modes of action of prophylactic dressings has focused on the Mepilex Border dressing (Mölnlycke Health Care AB, Gothenburg, Sweden). Published work has revealed several key design features that are pivotal for obtaining successful clinical outcomes, namely, (1) a multilayered alternating-stiffness structure with embedded anisotropy; (2) a minimal friction coefficient at the external surface of the dressing; and (3) low impact of fluid retention on the mechanical behavior of the dressing. These features, their importance, and the methods of identifying their roles in the modes of action of effective prophylactic dressings are detailed here.Computer models clearly inform the process of engineering prophylactic dressings, but they may also provide guidance in clinical use, contribute to assessing technologies and products, support purchasing, and describe product endurance. As the methods of FE modeling of dressings improve, simulations may soon incorporate the simultaneous complex interactions among tissue distortion, heat transfer in tissue, and prophylactic dressings to inform patient care.

Objective: To determine changes in internal soft-tissue loads in the buttocks of individuals with a spinal cord injury (SCI), who undergo pathoanatomical changes during the first months and years following the occurrence of the SCI, while sitting on a contoured foam cushion (CFC) that has been fitted close to the time of the injury but has not been replaced in subsequent years., Design: Internal tissue loads in variant buttocks anatomies on a CFC were analyzed by means of finite element computer simulations. The pathoanatomical changes that are characteristic to SCI and were simulated here are: increase in fat tissue mass, intramuscular fat infiltration, muscle atrophy, and combinations of these conditions., Setting: Computational biomechanical modeling., Main Results: Simulating the aforementioned pathoanatomical changes consistently resulted in greater mechanical strain and stress magnitudes and more inhomogeneity in the loading state of muscle and fat tissues, with a more profound effect in fat. The simulations further indicated a clear trend of exacerbation in tissue exposure to loads as the pathoanatomical changes progress chronologically and the CFC is not replaced., Conclusions: A CFC that has been fitted at a time close to the SCI, but has not been replaced in subsequent years, substantially loses its efficacy in protecting patients from developing pressure ulcers and deep tissue injury in particular.