Bioimpedance as an indicator in the distribution of interface pressure in vulnerable regions for pressure ulcers: A preliminary study

BackgroundIncreased elevation of the head of the bed is linked to a higher risk for sacral pressure ulcers. A semirecumbent position of at least 30° is recommended for the prevention of ventilator-associated pneumonia in patients treated with mechanical ventilation. Therefore, prevention of pressure ulcers and prevention of pneumonia seem to demand contradictory, possibly incompatible, positioning.ObjectivesTo measure pressure at the interface between sacral skin and the supporting surface in healthy volunteers at different degrees of upright position with different types of mattresses.MethodsAn open, prospective, randomized crossover trial was conducted with 20 healthy volunteers. Interface pressure was measured by using a pressure mapping device with the participant in a supine position at 0, 10°, 30°, and 45° elevation and in the reverse Trendelenburg position at 10° and 30°. Four types of mattresses were examined: 2 different foam mattresses and 2 air suspension beds, 1 of the latter with low-air-loss technology.ResultsPeak sacral interface pressures increased significantly only at 45° of backrest elevation (P < .001). A mattress system with low-air-loss technology significantly reduced peak interface pressures at all angles (P < .001). The reverse Trendelenburg position led to lower peak pressures for all positions (P = .01).ConclusionsBackrest elevation up to 30° might be a compromise between the seemingly incompatible demands of skin integrity and the prevention of ventilator-associated pneumonia. The reverse Trendelenburg position and a mattress system with low-air-loss technology could be additional useful tools to help prevent skin breakdown at the sacrum.

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A Comparative Study of 2-Hour Interface Pressure in Different Angles of Laterally Inclined, Supine, and Fowler’s Position

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18199992 ◽

2021 ◽

Vol 18 (19) ◽

pp. 9992

Author(s):

Soo-Yeon Kim ◽

Yong-Soon Shin

Keyword(s):

Comparative Study ◽

Pressure Difference ◽

Pressure Ulcers ◽

Peak Pressure ◽

Area Ratio ◽

The Other ◽

Pressure Measurements ◽

Interface Pressure ◽

Risk Area ◽

Position Change

Insufficient research exists for position change intervals to eradicate pressure ulcers. We tried to provide evidence for the position change interval by comparing peak pressure, risk area ratio, and the time to reach 30 mmHg and 60 mmHg, and presented this in detail, according to the angle in the three positions. The study conducted RCTs on a total of 64 healthy adults. For two hours, interface pressure measurements were compared with 30° and 90° tilting at the inclined, 0° and 45° head-of-bed (HOB) elevation at the supine, and 30° and 45° HOB elevation at the Fowler’s position. The peak pressure on 30° tilting remained less than 60 mmHg for 2 h, unlike 90° tilting. To reach 60 mmHg took 78.18 min at 30° tilting, within 30 min at the 30° supine, 30° and 45° at the Fowler’s position, and 39.55 min at 0° supine. The pressure difference according to the angles was only significant at 30° and 90° tilting, with no difference in the other groups. To prevent pressure ulcers, position changes are required every 2 h in the 30° tilting position, every 1.5 to 2 h at 0° supine, and at least every 1.5 h for all the other positions.

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Efeito de posturas estáticas e dinâmicas na distribuição da pressão nádega-almofada em um caso de tetraplegia por lesão medular/The effect of statistical and dynamic positions in the distribution of buttock-cushion pressure in a case of tetraplegia

Revista Interinstitucional Brasileira de Terapia Ocupacional - REVISBRATO ◽

10.47222/2526-3544.rbto15997 ◽

2018 ◽

Vol 2 (3) ◽

pp. 555-566

Author(s):

Paulo Vinicius Braga Mendes ◽

Daniel Marinho Cezar Da Cruz

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Contact Area ◽

Pressure Ulcers ◽

Peak Pressure ◽

Interface Pressure ◽

High Profile ◽

Cord Injury ◽

Mean Pressure ◽

Pressure Peak

Introdução: as úlceras por pressão são complicações frequentes em pacientes com lesão medular. Almofadas de ar são apontadas como as mais indicadas para aliviar a pressão de interface e prevenir úlceras. Objetivo: Analisar, em um caso de tetraplegia por lesão medular, o efeito da distribuição da pressão de interface nádega/almofada em posturas estáticas e dinâmicas e verificar se o uso de uma almofada nova interfere na distribuição da pressão. Método: A análise da pressão de interface foi realizada durante duas situações distintas: com o participante sentado em postura estática; e mais uma etapa utilizando a cadeira de rodas para a locomoção. Para a avaliação da pressão de interface foram utilizadas duas almofadas Roho® Quadtro Select High Profileâ„¢: uma em uso pela participante e outra fornecida pelos pesquisadores. Resultados: Foram analisados: pressão média, pico de pressão e área de contato na interface nádega/almofada nas duas etapas de coletas de dados. A almofada fornecida pelo estudo apresentou índices melhores para pressão média, pico de pressão e área de contato. Conclusão: O estudo traz evidências da importância de manter a calibração de almofadas para sujeitos lesados medulares para prevenção de úlceras de pressão. Abstract Introduction: pressure ulcers are frequent complications in patients with spinal cord injury. Air cushions are appointed as the most appropriate to relieve the interface pressure and prevent pressure ulcers. Objective: To analyze the effect of the distribution of the buttock / cushion interface pressure under static and dynamic posture and check the use of a new cushion interferes with the pressure distribution in a case of tetraplegia after spinal cord injury. Method: Analysis of interface pressure was performed for two different situations, with the participant sitting in static and one more step using the wheelchair for locomotion. For the evaluation of interface pressure were used two Roho® Quadtro Select High Profile â„¢ cushions: one used by the participant and another provided by the researchers. Resulted: Was analyzed the mean pressure, peak pressure and the contact area in buttock/cushion in both data collect. The cushion provided by the study presented better indices for mean pressure, peak pressure and contact area. Conclusion: The study provides evidence of the importance of maintaining cushion calibration for spinal cord injured individuals to prevent pressure ulcers.Keywords: Cushion; Spinal Cord Injury; Assistive Technology.

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Relationship Between the Frictional Shear Stresses and the Normal Pressure on the Buttocks While Lying on a Spine Board

Volume 3: Biomedical and Biotechnology Engineering ◽

10.1115/imece2019-11814 ◽

2019 ◽

Author(s):

Vinay Kumar Pallerla ◽

Mohamed Samir Hefzy

Keyword(s):

Finite Element ◽

Pressure Ulcers ◽

Normal Pressure ◽

Element Model ◽

Human Anatomy ◽

Shear Stresses ◽

Interface Pressure ◽

3D Cad ◽

Young’S Moduli ◽

Spine Board

Abstract Cushions have been used on spine boards to reduce the interface pressure acting on the skin and thus prevent the formation of pressure ulcers. Several studies have focused on determining how using different types of cushions can reduce the normal interface pressure on the buttocks while lying on the spine boards. On the other hand, and while it has been agreed upon that the shear stresses contribute to the formation of pressure ulcers, this role has not been understood or quantified. The purpose of this work is to use 3-D finite element modeling to determine the contact frictional shear stresses at the buttocks while an individual is lying on a spine board when cushions of various stiffnesses are used. The Zygote Solid 3D Male Human Anatomy model was used to construct a 3D CAD model of a section of the human body in the pelvic region. Skin, fat, muscles and bones were identified in the model. The Zygote SolidWorks model, the HyperMesh finite element preprocessor, and the ABAQUS software were used to create the finite element model. Bones were considered as an elastic isotropic material whereas skin, fat and muscles were modeled using Hyperelastic Neo-Hookean materials. Results were obtained to find the effects of body weight on the shear stresses while a person is lying flat with his buttocks contacting the spine board. The results indicate that frictional skin shear stresses cannot be ignored since they were found to be, and depending on the cushion material, about 15% to 35% of the maximum normal pressure. We propose, and for the first time, a relationship to estimate the maximum shear stresses at the buttocks in terms of the maximum normal pressure for different Young’s moduli of cushions. These results can also be used as a guide to select cushion material that minimize normal and shear interface stresses.

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Stump-socket interface pressure as an aid to socket design in prostheses for trans-femoral amputees—a preliminary study

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1243/0954411971534287 ◽

1997 ◽

Vol 211 (2) ◽

pp. 167-180 ◽

Cited By ~ 42

Author(s):

V S P Lee ◽

S E Solomonidis ◽

W D Spence

Keyword(s):

Pressure Distribution ◽

Pressure Profile ◽

Load Cell ◽

Maximum Pressure ◽

Interface Pressure ◽

Preliminary Study ◽

Socket Interface ◽

Lateral Walls ◽

Distributed Pressure

A system for measuring the stump-socket interface pressure was designed and built using a strain gauged type load cell. The system was utilized to study the pressure distribution in the quadrilateral and ischial containment type sockets. Two volunteer trans-femoral amputees fitted with both types of socket participated in the experiments. Pressures were measured while the subjects were standing and during walking. The maximum pressure recorded for standing was 34 kPa and for walking 95 kPa. Comparison made between the two sockets indicated that higher pressures were recorded at the proximal brim of the quadrilateral socket whereas the ischial containment socket produces a more evenly distributed pressure profile. The pressure distribution on the medial and lateral walls of both types of sockets were similar but in the anterior and posterior walls, significant differences were noted. The results obtained from this study were compared with those found in published literature and the biomechanics of the two types of socket is discussed.

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Towards the Development of an Alternating Pressure Overlay for the Treatment of Pressure Ulcers Using Miniaturised Air Cells

Proceedings ◽

10.3390/iecat2020-08522 ◽

2020 ◽

Vol 64 (1) ◽

pp. 33

Author(s):

Malindu Ehelagastenna ◽

Ishan Sumanasekara ◽

Hishan Wickramasinghe ◽

Indrajith D. Nissanka ◽

Gayani K. Nandasiri

Keyword(s):

Pressure Ulcers ◽

High Pressures ◽

Integrated Control ◽

Control Unit ◽

Back Pressure ◽

The Body ◽

Support Surface ◽

Interface Pressure ◽

Tissue Pressure ◽

Actuator System

This paper presents a study on design and development of an alternating pressure overlay consists of inflatable mini air bladders, which could be used in relieving and reducing tissue pressure for the treatment of pressure ulcers. Pressure ulcers, which are predominant in the bony prominences of the body, is a skin deformity due to the limitation of blood circulation to the muscle tissues as a result of high pressures applied on the skin for longer duration. This research aims to design miniaturised air bladders which could provide alternating pressure sequences for the treatment of the pressure ulcers. The optimally designed air bladders provide proper envelopment of the patient’s body and create a high resolution of pressure distribution. The optimum geometry and the 3-D deformation profile of the air bladders are analysed using the finite element method. Based on the interface pressure the pressure overlay has been divided into five pressure zones. Furthermore, the real-time interface pressure profile between the body and the overlay is mapped by using the back pressure of mini air bladders. The actuator system includes an integrated control unit that regulates the internal pressures via electropneumatic valves operated based on the back pressure sensor feedback. This actuator system provides the alternating pressure patterns required for inflation and deflation of the mini air bladders controlling the airflow of the support surface, providing proper pressure distributions to heal the ulcers.

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Reduced pressure for fewer pressure ulcers: can real-time feedback of interface pressure optimise repositioning in bed?

International Wound Journal ◽

10.1111/iwj.12374 ◽

2014 ◽

Vol 13 (5) ◽

pp. 774-779 ◽

Cited By ~ 10

Author(s):

Lena Gunningberg ◽

Cheryl Carli

Keyword(s):

Real Time ◽

Pressure Ulcers ◽

Interface Pressure ◽

Reduced Pressure

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The effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements

Prosthetics and Orthotics International ◽

10.1177/0309364613486918 ◽

2013 ◽

Vol 38 (1) ◽

pp. 46-53 ◽

Cited By ~ 10

Author(s):

Lorna H Tasker ◽

Nigel G Shapcott ◽

Alan J Watkins ◽

Paul M Holland

Keyword(s):

Pressure Ulcer ◽

Pressure Ulcers ◽

Three Dimensional ◽

Support Surface ◽

Pressure Measurements ◽

Interface Pressure ◽

Pressure Mapping ◽

Shape Acquisition ◽

Surrogate Measures ◽

Interface Pressures

Background: It is clinically known that shape is important when selecting or designing a wheelchair support surface for the prevention of pressure ulcers (a £2 billion annual cost to the National Health Service, UK); however, the effect of different levels of shape contouring has not been adequately studied. Objectives: To investigate the effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements. Study design: Randomised, repeated trial. Methods: Thirty able-bodied participants sat with restricted movement for 30 min in three sessions to evaluate two cushion shapes against a flat baseline surface. Visual Analog Scaling and pressure mapping were used to measure surrogates for pressure ulcer risk, discomfort and interface pressures, respectively. Results: Linear regression revealed a reduction in discomfort ( p < 0.05) on the custom contoured shapes. Interface pressures measured were also lower ( p < 0.05) on the custom contoured shapes, and a negative Pearson’s correlation ( p < 0.05) indicated an association between smaller hip widths and increased discomfort for the commercially shaped cushion. Conclusions: The results of this study confirm that custom contoured shapes were effective at reducing pressure ulcer surrogate measures in the participants of this study and therefore suggests that the contribution of a cushion’s three-dimensional contours on pressure ulcer risk should be further researched. Clinical relevance The measurement of seat shape, discomfort and interface pressure in surrogate participants can help inform the design of wheelchair seating for individuals who are insensate or otherwise at risk of developing pressure ulcers. This knowledge can now be implemented using modern three-dimensional shape acquisition, analysis and fabrication technologies.

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