1,721,103 research outputs found
The physiological response of skin tissues to alternating support pressures in able-bodied subjects
No full textProlonged mechanical loading can lead to breakdown of skin and underlying tissues which can, in turn, develop into a pressure ulcer. The benefits of pressure relief and/or redistribution to minimise risk have been well documented and these strategies can be provided by employing support mattresses in which internal air pressures can be alternated to minimise the risk of pressure ulcers in patients during prolonged periods of bed-rest. The paper describes the performance of a prototype alternating pressure air mattress (APAM), in terms of its ability to maintain skin viability in a group of healthy volunteers lying in a supine position. In particular, the mattress includes a sacral section supported with alternating low pressure (ALP), with values adjusted to subject morphology, using an in-built pressure sensor. The mattress was supported at four different head of bed (HOB) angles ranging from 0 to 60°. Internal mattress pressures and transcutaneous gas (TcPO2/TcPCO2) tensions at the sacrum and a control site, the scapula, were monitored. Interface pressures were also measured. The sensor was found to be sensitive to the BMI values of the 12 healthy volunteers. In the majority of test conditions the internal support produced sacral TcPO2 values, which either remained similar to those at the scapula or fluctuated at levels providing adequate viability. However in a few cases, associated with a raised HOB angle (?45°), there was compromise to the skin viability at the sacrum, as reflected in depressed TcPO2 levels associated with an elevation of TcPCO2 levels above the normal range. In all cases, interface pressures at the sacrum rarely exceeded 60mmHg. Although such studies need to be extended to involve bed-bound individuals, the results offer the potential for the development of intelligent APAM systems, whose characteristics can be adjusted to an individual morphology. Such preventive strategies to maintain skin viability at loaded sites will be designed for subjects deemed to be at high risk of developing pressure ulcers
Dataset: Respiratory Mask Goodness of Fit Evaluation
No full textRespiratory Mask Goodness of Fit Evaluation using AmpScan 3D image registration software.
Dataset supports: J.W.R Verberne, P.R. Worsley, D.L. Bader. A 3D registration methodology to evaluate the goodness of fit at the individual-respiratory mask interface, Computer Methods in Biomechanics and Biomedical Engineering, http://dx.doi.org/10.1080/10255842.2020.1849156</span
Biomechanical analysis of structural deformation in living cells
Full text linkMost tissues are subject to some form of physiological mechanical loading which results in deformation of the cells triggering intracellular mechanotransduction pathways. This response to loading is generally essential for the health of the tissue, although more pronounced deformation may result in cell and tissue damage. In order to determine the biological response of cells to loading it is necessary to understand how cells and intracellular structures deform. This paper reviews the various loading systems that have been adopted for studying cell deformation both in situ within tissue explants and in isolated cell culture systems. In particular it describes loading systems which facilitate visualisation and subsequent quantification of cell deformation. The review also describes the associated microscopy and image analysis techniques. The review focuses on deformation of chondrocytes with additional information on a variety of other cell types including neurons, red blood cells, epithelial cells and skin and muscle cell
Reliability testing of vasti activity measurements in taped and untaped patellofemoral conditions during single leg squatting in healthy subjects: A pilot study
No full textINTRODUCTION: Measuring vasti muscles activity may provide reliable evidence for patellar taping to correct probable malalignment in subjects with patellofemoral pain syndrome (PFPS). The aim of present study was to examine the reliability of vasti activity measurements in different patellofemoral conditions during squatting in healthy subjects.METHODS: Using an electromyography (EMG) unit, the ratio amplitudes and onsets of VMO and VL muscles of twelve healthy subjects were assessed during single leg squatting. Data was collected from surface electrodes placed over the muscle bellies of the VMO and VL. This procedure was performed on the right knees, before (BT), during (WT) and shortly after patellar taping (SAT).RESULTS: While the CV (coefficient of variation), ICC (intra class correlation coefficient), LSD (least significant difference) and SEM (standard error of measurement) values revealed the high reliability of the VMO/VL amplitude measurements during single leg squatting (p < 0.05), the related values demonstrated poor to moderate reliability of VMO-VL onset measurements during the similar activity (p > 0.05).CONCLUSION: Reliability tests conducted during the current study showed that, while the relative amplitude of vasti could be used as highly reliable parameter, the muscle onsets of vasti had poor to moderate reliability
An evaluation of fluid immersion therapy for the prevention of pressure ulcers
No full textBackground: Individuals with impaired mobility can spend prolonged periods on support surfaces, increasing their risk of developing pressure ulcers. Manufacturers have developed mattresses to maximise contact area. The present study evaluated both the biomechanical and physiological responses to lying postures on a Fluid Immersion Simulation mattress.Methods: Seventeen healthy participants were recruited to evaluate the mattress during three prescribed settings of immersion (high, medium and low). Parameters reflecting biomechanical and physiological responses, and the microclimate were monitored during three postures (supine, lateral and high-sitting) over a 90 minute test session. Transcutaneous oxygen and carbon dioxide gas responses were categorised according to three criteria and data were compared between each condition.Findings: Results indicated that interface pressures remained consistent, with peak sacral values ranging from 21 to 27 mm Hg across all immersion settings and postures. The majority of participants (82%) exhibited minimal changes in gas tensions at the sacrum during all test conditions. By contrast, three participants exhibited decreased oxygen with increased carbon dioxide tensions for all three immersion settings. Supine and high sitting sacral microclimate values ranged between 30.1–30.6 °C and 42.3–44.5% for temperature and relative humidity respectively. During lateral tilt there was a reduction of 1.7–2.5 °C and 3.3–5.3% in these values. The majority of participants reported high comfort scores, although a few experienced bottoming out during the high-sitting posture at the high immersion setting.Interpretation: Fluid Immersion Simulation provides an intelligent approach to increase the support area. Further research is required to provide evidence based guidance on the use of personalised support surfaces
Mechanical loading modulates intracellular calcium signaling in human mesenchymal stem cells
No full textMesenchymal stem cells (MSCs) are a promising cell source for tissue-engineered connective tissue repair strategies. Additionally, increasing evidence confirms the role of the mechanical environment in maintaining tissue homeostasis, with calcium signaling implicated as a mediator in mechanotransduction pathways. Spontaneous intracellular calcium signaling was observed in a subset of MSCs embedded within 4% alginate hydrogel constructs, measured by a Ca2+ indicator fluo-4 in conjunction with confocal laser-scanning microscopy. By the use of pair-wise analysis, it was shown that distinct populations of MSCs up-regulated and down-regulated the frequency of calcium transients with the application of a 20% static uniaxial compressive strain of 20 min duration, delivered after a 20 min unstrained period. Calcium transients in control specimens were monitored throughout two unstrained 20 min periods. These values were statistically significant (p<0.05) by ?2 test of independence. This dual-response indicator highlights the heterogeneous nature of MSC populations, which may have important implications for their successful use in cell therapies. (Journal of Applied Biomaterials &Biomechanics 2008; 6: 9-15
Bioengineering considerations in the prevention of medical device-related pressure ulcers
No full textBackgroundIn recent years, it has become increasingly apparent that medical device-related pressure ulcers represent a significant burden to both patients and healthcare providers. Medical devices can cause damage in a variety of patients from neonates to community based adults. To date, devices have typically incorporated generic designs with stiff polymer materials, which impinge on vulnerable soft tissues. As a result, medical devices that interact with the skin and underlying soft tissues can cause significant deformations due to high interface pressures caused by strapping or body weight.MethodsThis review provides a detailed analysis of the latest bioengineering tools to assess device related skin and soft tissue damage and future perspectives on the prevention of these chronic wounds. This includes measurement at the device-skin interface, imaging deformed tissues, and the early detection of damage through biochemical and biophysical marker detection. In addition, we assess the potential of computational modelling to provide a means for device design optimisation and material selection.InterpretationFuture collaboration between academics, industrialists and clinicians should provide the basis to improve medical device design and prevent the formation of these potentially life altering wounds. Ensuring clinicians report devices that cause pressure ulcers to regulatory agencies will provide the opportunity to identify and improve devices, which are not fit for purpose
Dataset supporting a PhD Thesis "Long-term monitoring of persons with spinal cord injury (sci): implication for pressure ulcer development"
No full textDataset supporting a PhD Thesis "Long-term monitoring of persons with spinal cord injury (sci): implication for pressure ulcer development".
The data includes patient ID, ASIA score, level of spinal cord injury, predicted time and frequency of bed and chair movements, observed time and frequency of bed and chair movements.
Two timepoints are described, separated by tabs.
1. Inpatient rehabilitation (timepoint 1)
2. Community monitoring after hospital discharge (timepoint 2).
Licence:
CC-BY license
Related projects/Funders:
Salisbury NHS Foundation Trust, Engineering and Physical Sciences Research Council.
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Investigating the influence of intermittent and continuous mechanical loading on skin through non-invasive sampling of IL-1α
No full textPressure ulcers (PUs) are a major burden to both patients, carers and the healthcare system. It is therefore important to identify patients at risk and detect pressure ulcers at an early stage of their development. The pro-inflammatory cytokine IL-1α is a promising indicator of tissue damage. The aim of this study was to compare the temporal skin response, by means of IL-1α expression, to different loading regimens and to investigate the presence of individual variability. The sacrum of eleven healthy volunteers was subjected to two different loading protocols. After a baseline measurement, the left and right side of the sacrum were subjected to continuous and intermittent loading regimen, respectively, at a pressure of 100 mmHg. Data was collected every 20 min, allowing for a total experimental time of 140 min. Sebum, collected at ambient conditions using Sebutape, was analyzed for the pro-inflammatory cytokine IL-1α. Most robust results were obtained using a baseline normalization approach on individual data. The IL-1α level significantly changed upon load application and removal (p<0.05) for both loading regimens. Highest IL-1α ratio increase, 3.7-fold, was observed for 1 h continuous loading. During the refractory periods for both loading regimen the IL-1α levels were still found to be up-regulated compared to baseline (p<0.05). The IL-1α level increased significantly for the two initial loading periods (p<0.05), but stabilized during the final loading period for both loading regimens. Large individual variability in IL-1α ratio was observed in the responses, with median values of 1.91 (range 1.49–3.08), and 2.52 (range 1.96–4.29), for intermittent and continuous loading, respectively, although the differences were not statistically significant. Cluster analysis revealed the presence of two distinct sub-populations, with either a low or high response to the applied loading regimen. The measurement after the first loading period proved to be representative for the subsequent measurements on each site. This study revealed that trends in normalized IL-1α provided an early indicator for tissue status following periods of mechanical loading and refractory unloaded conditions. Additionally, the observed individual variability in the response potentially identifies patients at risk of developing PUs.</p
Evaluating the effects of sedentary behaviour on plantar skin health in people with diabetes
No full textBackground
Diabetes-Related Foot Ulcers (DRFUs) are a common and devastating consequence of Diabetes Mellitus and are associated with high morbidity, mortality, social and economic costs. Whilst peak plantar pressures during gait are implicated cited as a major contributory factor, DRFU occurrence has also been associated with increased periods of sedentary behaviour. The present study was designed aimed to assess the effects of sitting postures on plantar tissue health.
Methods
After a period of acclimatisation, transcutaneous oxygen tensions (TCPO2) and inflammatory cytokines (IL-1α and IL-1RA) were measured at the dorsal and plantar aspects of the forefoot before, during and after a 20-min period of seated-weight-bearing in participants with diabetes (n = 11) and no diabetes (n = 10). Corresponding interface pressures at the plantar site were also measured.
Results
During weight-bearing, participants with diabetes showed increases in tissue ischaemia which were linearly correlated proportional to plantar pressures (Pearson's r = 0.81; p < 0.05). Within the healthy group, no such correlation was evident (p > 0.05). There were also significant increases in post seated weight-bearing values for ratio for IL-1α and IL-1RA, normalised to total protein, post seated weight-bearing in participants with diabetes compared to healthy controls.
Conclusion
This study shows that prolonged sitting may be detrimental to plantar skin health. It highlights the need to further examine the effects of prolonged sitting in individuals, who may have a reduced tolerance to loading in the plantar skin and soft tissues
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