The aetiology of medical device-related pressure ulcers and how to prevent them

2021 ◽  
Vol 30 (15) ◽  
pp. S24-S30
Author(s):  
Amit Gefen
Keyword(s):  
Medical Device ◽  
Soft Tissues ◽  
Pressure Ulcers ◽  
Positive Airway Pressure ◽  
Cell Damage ◽  
Facial Skin ◽  
Vicious Cycle ◽  
Ischaemic Damage ◽  
Clinical Scenarios ◽  
Tissue Deformations

This article provides an introduction to the aetiology of medical device-related pressure ulcers (MDRPUs), describes the vicious cycle that leads to these injuries and highlights bioengineering methodologies and findings that connect the aetiology to the clinical practice of preventing MDRPUs. Specifically, the vicious cycle of MDRPUs is triggered by the sustained tissue deformations induced by a skin-contacting device. The primary, deformation-inflicted cell damage leads to a secondary inflammatory-oedema-related damage and then to tertiary ischaemic damage. Each of these three factors contributes to cumulative cell death and tissue damage under and near the applied device. The damage therefore develops in an escalated manner, as a result of the added contributions of the above three factors. This phenomenon is exemplified through two common clinical scenarios. First, through the use of continuous positive airway pressure (CPAP) masks, which are being applied extensively in the current COVID-19 pandemic, and, second, through the use of doughnut-shaped head positioners, which are applied to surgical patients and sometimes to bedridden individuals who receive intensive care in a supine position. These two medical devices cause intense, localised mechanical loads in the facial skin and underlying tissues (CPAP mask) and at the occipital scalp (doughnut-shaped positioner), where the soft tissues cannot swell in response to the inflammatory oedema as, in both cases, the tissues are sandwiched between the device and the skull. Accordingly, the two device types result in characteristic MDRPUs that are avoidable through appropriate prophylactic interventions, that is, preventive dressings under the CPAP mask and replacement of the doughnut device by a soft, shape-conforming support aid to alleviate and disperse the localised soft tissue deformations. Hence, understanding the aetiology of MDRPUs targets and focuses effective clinical interventions.

scholarly journals Lateral pressure equalisation as a principle for designing support surfaces to prevent deep tissue pressure ulcers

2019 ◽  
Author(s):  
Colin J. Boyle ◽  
Diagarajen Carpanen ◽  
Thanyani Pandelani ◽  
Claire A. Higgins ◽  
Marc A. Masen ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Pressure Ulcers ◽  
Lateral Pressure ◽  
Element Model ◽  
Von Mises Stress ◽  
Deep Tissue ◽  
Tissue Pressure ◽  
Support Surfaces ◽  
Von Mises ◽  
Tissue Deformations

AbstractWhen immobile or neuropathic patients are supported by beds or chairs, their soft tissues undergo deformations that can cause pressure ulcers. Current support surfaces that redistribute under-body pressures at vulnerable body sites have not succeeded in reducing pressure ulcer prevalence. Here we show that adding a supporting lateral pressure can counter-act the deformations induced by under-body pressure, and that this ‘pressure equalisation’ approach is a more effective way to reduce ulcer-inducing deformations than current approaches based on redistributing under-body pressure.A finite element model of the seated pelvis predicts that applying a lateral pressure to the soft tissue reduces peak von Mises stress in the deep tissue by a factor of 2.4 relative to a standard cushion — a greater effect than that achieved by using a more conformable cushion. The ratio of peak lateral pressure to peak under-body pressure was shown to regulate deep tissue stress better than under-body pressure alone. By optimising the magnitude and position of lateral pressure, tissue deformations can be reduced to that induced when suspended in a fluid.Our results explain the lack of efficacy in current support surfaces, and suggest a new approach to designing and evaluating support surfaces: ensuring sufficient lateral pressure is applied to counter-act under-body pressure.

The study for constant force characteristic of C-shaped superelastic SMA

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1253-1259
Author(s):  
Minghui Wang ◽  
Hongliu Yu
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Medical Device ◽  
Soft Tissues ◽  
Computational Simulation ◽  
Force Characteristic ◽  
Constant Force ◽  
Curve Shape ◽  
Artificial Sphincter ◽  
Round Bar

Clamping devices with constant force or pressure are desired in medical device, such as hemostatic forceps and the artificial sphincter, to prevent soft tissues from injures due to overloading. It is easily obtained by stretching an SMA wire. However, studies with SMA bending round bar have seldom been reported before. This paper studied constant force characteristic of C-shaped round bar with shape memory alloys. Optimization designs of the components were carried out with computational simulation. Numerical results show that the phenomenon of constant force strongly depends on contour curve shape and geometric dimensions of the C-shaped round bar of SMA component.

An Investigation Into the Upper Arm Deformation Under Inflatable Cuff

2008 ◽  
Author(s):  
H. Lan ◽  
A. M. Al-Jumaily ◽  
A. Lowe
Keyword(s):  
Finite Element ◽  
Soft Tissues ◽  
Element Model ◽  
Upper Arm ◽  
Inflatable Cuff ◽  
Proposed Model ◽  
Materials Used ◽  
Tissue Deformations ◽  
Visible Human ◽  
Collapse Process

The human upper arm is simulated using a nonlinear geometrical and physical model. To create a more realistic simulation, the geometry of the model is based on the visible human body dataset. The model consists of four parts, humerus, brachial artery, muscle, and other soft tissues. All the materials used in this model are assumed to be incompressible and hyperelastic. The unique properties of each material are specified and described. Incorporating all of these facts, a finite element model is developed using the commercial programme ABAQUS®. The upper arm tissues’ deformations and artery collapse process under compression are simulated in this model. The proposed model has the potential to simulate the tissue deformations under inflatable cuffs exposed to arm movements.

A FAST COMPUTATION METHOD FOR SOFT TISSUE DEFORMATIONS SIMULATION BASED ON SELF-SELECTION ALGORITHM FOR EMBEDDED OPERATING AREA

2017 ◽  
Vol 17 (07) ◽  
pp. 1740016
Author(s):  
MONAN WANG ◽  
ZHIYONG MAO ◽  
XIANJUN AN
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Nonlinear Problems ◽  
Rectus Femoris ◽  
Computation Method ◽  
Biomechanical Models ◽  
Simulation Based ◽  
Material Nonlinear ◽  
Tissue Deformations ◽  
Tissue Models

This study used biomechanical models of soft tissues based on combined exponential and polynomial models. Finite element methods were used to solve material nonlinear and geometrically nonlinear problems of soft tissue models. This involved assigning a screening coefficient in the model-accelerated computing process to filter the units involved in the calculation. The screening coefficient controlled both the accuracy of the results of simulation and the computing speed through setting up a subset of finite elements. The fast computer method based on the screening coefficient was applied to the rectus femoris simulation.

scholarly journals Incidence and risk factors for medical device‐related pressure ulcers: The first report in this regard in Iran

2019 ◽  
Vol 17 (2) ◽  
pp. 436-442 ◽  
Author(s):  
Farnoosh Rashvand ◽  
Lida Shamekhi ◽  
Hossein Rafiei ◽  
Mohammad Nosrataghaei
Keyword(s):  
Risk Factors ◽  
Medical Device ◽  
Pressure Ulcers ◽  
First Report

scholarly journals HUS and atypical HUS

Blood ◽  
2017 ◽  
Vol 129 (21) ◽  
pp. 2847-2856 ◽  
Author(s):  
T. Sakari Jokiranta
Keyword(s):  
Shiga Toxin ◽  
Complement Activation ◽  
Cell Damage ◽  
Gastrointestinal Infection ◽  
Vicious Cycle ◽  
Intravascular Hemolysis ◽  
Endothelial Cell Damage ◽  
Atypical Hus ◽  
Uremic Syndrome ◽  
The Common

Abstract Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis, thrombocytopenia, and acute kidney failure. HUS is usually categorized as typical, caused by Shiga toxin–producing Escherichia coli (STEC) infection, as atypical HUS (aHUS), usually caused by uncontrolled complement activation, or as secondary HUS with a coexisting disease. In recent years, a general understanding of the pathogenetic mechanisms driving HUS has increased. Typical HUS (ie, STEC-HUS) follows a gastrointestinal infection with STEC, whereas aHUS is associated primarily with mutations or autoantibodies leading to dysregulated complement activation. Among the 30% to 50% of patients with HUS who have no detectable complement defect, some have either impaired diacylglycerol kinase ε (DGKε) activity, cobalamin C deficiency, or plasminogen deficiency. Some have secondary HUS with a coexisting disease or trigger such as autoimmunity, transplantation, cancer, infection, certain cytotoxic drugs, or pregnancy. The common pathogenetic features in STEC-HUS, aHUS, and secondary HUS are simultaneous damage to endothelial cells, intravascular hemolysis, and activation of platelets leading to a procoagulative state, formation of microthrombi, and tissue damage. In this review, the differences and similarities in the pathogenesis of STEC-HUS, aHUS, and secondary HUS are discussed. Common for the pathogenesis seems to be the vicious cycle of complement activation, endothelial cell damage, platelet activation, and thrombosis. This process can be stopped by therapeutic complement inhibition in most patients with aHUS, but usually not those with a DGKε mutation, and some patients with STEC-HUS or secondary HUS. Therefore, understanding the pathogenesis of the different forms of HUS may prove helpful in clinical practice.

Axial Strain Measurements in Skeletal Muscle at Various Strain Rates

1995 ◽  
Vol 117 (3) ◽  
pp. 262-265 ◽  
Author(s):  
T. M. Best ◽  
J. H. McElhaney ◽  
W. E. Garrett ◽  
B. S. Myers
Keyword(s):  
Skeletal Muscle ◽  
Strain Field ◽  
High Speed ◽  
Soft Tissues ◽  
Axial Strain ◽  
Local Strain ◽  
Optical Systems ◽  
Rate Dependent ◽  
Strain Formulation ◽  
Tissue Deformations

A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

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