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.

Medical Device Testing: Methods, Significance, and Clinical Applications.

General Purpose: To present a study conducting objective biomechanical testing of medical devices known to cause medical device-related pressure injuries (MDRPIs) in critically ill adults and comparing those results with clinical outcomes associated with each device.

Target Audience: This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

Learning Objectives/outcomes: After participating in this educational activity, the participant will:1.

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'.

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.

Effective negative pressure wound therapy for open wounds: The importance of consistent pressure delivery.

Two distinct design concepts exist for single-use negative pressure wound therapy systems: Canister-based versus canisterless. The canister-based technology provides intrinsic stable delivery of the intended negative pressure, because exudate is constantly transferred from the wound into a canister, thereby preventing dressing saturation. In contrast, with a canisterless system, where delivery of the negative pressure depends on continuous evaporation of wound fluids from its dressing, loss of the intended wound-bed pressure may occur due to dressing saturation.

Fluid Handling Dynamics and Durability of Silver-Containing Gelling Fiber Dressings Tested in a Robotic Wound System.

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.

The fluid handling performance of the curea P1 multipurpose dressing against superabsorbent and foam dressing technologies.

Using a novel, automated robotic phantom system containing multiple wound simulants, we determined the fluid handling performance of the curea P1 multipurpose dressing vs market-leading comparator superabsorbent and foam-based dressings (FBDs). Specifically, we measured the retained, residual, evaporated, and (potentially occurring) spillover fluid shares for high- vs low-viscosity exudate-simulant test fluids, at 12, 24, and 30 hours postapplication of the dressings. These experiments were conducted for off-loaded ('prone'), non-off-loaded ('supine'), and vertical ('side-lying') simulated body positions.

The potential of a canister-based single-use negative-pressure wound therapy system delivering a greater and continuous absolute pressure level to facilitate better surgical wound care.

Two types of single-use negative-pressure wound therapy systems are currently available to treat surgical wounds: Canister-based and canisterless. This work was aimed to evaluate the performance of a canister-based vs a canisterless system, each with a different negative-pressure setting and technology for fluid management. Continuous delivery of a specified level of negative pressure to the wound bed is hypothesised to be important for promoting surgical wound healing, by achieving continuous reduction of lateral tension in the wound, particularly through decrease of skin stress concentrations around suture insertion sites.

Wear Resistance of Ti-6Al-4V Alloy Ball Heads for Use in Implants.

The effect of thermohydrogen treatment and vacuum ion-plasma nitriding on the determination of the volume and surface structure of ball heads made of Ti-6Al-4V alloy was studied. It was found that the submicrocrystalline structure formed in the head during thermohydrogen treatment makes it possible to achieve hardness values of 39-41 units HRC and a surface roughness of 0.02 μm.

How influential is the stiffness of the foam dressing on soft tissue loads in negative pressure wound therapy?

Negative pressure wound therapy (NPWT) is an established adjunctive modality for treatment of both acute and chronic wounds. However, little is known about the optimal settings and combination of treatment parameters and importantly, how these translate to target tissue strains and stresses that would result the fastest healing and buildup of good-quality tissues. Here we have used a three-dimensional open wound computational (finite element) model that contains viscoelastic skin, adipose and skeletal muscle tissue components for determining the states of tissue strains and stresses in and around the wound when subjected to NPWT with foam dressings of varying stiffnesses.

The mechanobiology theory of the development of medical device-related pressure ulcers revealed through a cell-scale computational modeling framework.

Pressure ulcers are localized sites of tissue damage which form due to the continuous exposure of skin and underlying soft tissues to sustained mechanical loading, by bodyweight forces or because a body site is in prolonged contact with an interfacing object. The latter is the common cause for the specific sub-class of pressure ulcers termed 'medical device-related pressure ulcers', where the injury is known to have been caused by a medical device applied for a diagnostic or therapeutic purpose. Etiological research has established three key contributors to pressure ulcer formation, namely direct cell and tissue deformation, inflammatory edema and ischemic damage which are typically activated sequentially to fuel the injury spiral.

Hydrogen atoms in solid xenon: trapping site structure, distribution, and stability as revealed by EPR studies in monoisotopic and isotopically enriched xenon matrices.

Trapping and decay of hydrogen atoms generated by fast electron irradiation of solid xenon doped with small hydrogen-containing molecules (acetylene, water) were studied by EPR using monoisotopic (136)Xe matrix (I = 0) and highly isotopically enriched (129)Xe matrix (I = 12). It was found that more than 99% of H atoms observed by EPR are initially trapped in the octahedral interstitial trapping sites, whereas initial population of the substitutional trapping sites is very small (less than 1%). The (129)Xe hyperfine coupling tensor parameters for major trapping site were determined from direct measurements in a (136)Xe matrix doped with small amount of (129)Xe: A(0) ((129)Xe) = -92.

Infrared absorption and electron paramagnetic resonance studies of vinyl radical in noble-gas matrices.

Vinyl radicals produced by annealing-induced reaction of mobilized hydrogen atoms with acetylene molecules in solid noble-gas matrices (Ar, Kr, and Xe) were characterized by Fourier transform infrared and electron paramagnetic resonance (EPR) spectroscopies. The hydrogen atoms were generated from acetylene by UV photolysis or fast electron irradiation. Two vibrational modes of the vinyl radical (nu7 and nu5) were assigned in IR absorption studies.

Experimental evidence for the formation of HXeCCH: the first hydrocarbon with an inserted rare-gas atom.

Combined FTIR and EPR studies of acetylene irradiated with fast electrons in a solid xenon matrix provide experimental evidence for the formation of HXeCCH, a novel-type organic molecule with an inserted rare-gas atom. The new species resulting from the reaction of H atoms with CCH radicals in xenon was characterized by an intense IR absorption at 1486.0 cm(-1) corresponding to Xe-H stretching.