Review of interface pressure measurement to establish a protocol for their use in the assessment of patient support surfaces

Is skin pressure in load carriage over-evaluated?

Skin pressure is a biomechanical measure widely used in the assessment of load carriage systems. However, because of the complicated contour of human body, the stiffness of the pressure sensor array, and the large range of measurable pressures, there is much variability in previously reported results. In this paper, a simple mechanical model for load carriage was proposed, and the skin pressures beneath the shoulder and hip straps were predicted from the strap forces based on Laplace's law. The proposed model was used to analyze data from literature with an aim to check the reliability of existing pressure measurements. The static and dynamic pressures at five locations on eight subjects wearing a backpack with a 10 kg load, while standing and walking on a treadmill, were measured respectively using pressure sensors of the air pack type. The combination of literature data analysis and experimental testing proved that the existing measurement method of interface pressure in load carriage systems often leads to over-estimation and this might misguide the pressure criteria set for load carriage system usage and design. The proposed model will be useful for quick prediction of the interface pressure in load carriage systems.

Relationship between ultrasonographically low-echoic lesions under the skin, wheelchair sitting time, and interface pressure on ischial region in individuals with chronic spinal cord injury

Objective: To determine the relationship between physical findings, wheelchair sitting time, and interface pressure on ischial region in subjects with spinal cord injury (SCI).Design: Cross-sectional study.Setting: Rehabilitation center in Japan.Participants: Manual wheelchair users with chronic SCI (n = 45).Interventions: Pressure ulcers (PU) were diagnosed by inspection, palpation, and ultrasonography. Self-reports were obtained on wheelchair sitting time and pressure mapping was recorded while the subject was seated on the wheelchair.Outcome measures: Subjects were divided into those with ultrasonographically low-echoic lesions (PU-positive group, n = 11) and no such lesions (PU-negative group, n = 34). Outcome measures included wheelchair sitting time and interface pressure at bilateral ischial regions.Results: Using ultrasonography, 13 low-echoic lesions were identified in 11 subjects of the PU-positive group. The pressure duration was longer and interface pressure was significantly higher in subjects of the PU-positive group compared with those of the PU-negative group (P < 0.05 and P < 0.001, respectively).Conclusions: This is the first study to evaluate the interrelationship between physical findings, sitting time, and ultrasonographically measured interface pressure on ischial region area in subjects with spinal cord injury. To prevent pressure ulcers, we recommend avoidance of prolonged wheelchair sitting and measures that can reduce the interface pressure. These variables should be carefully tailored to the needs of the individual subjects with SCI.

A narrative review on pressure ulcer (PU) studies relevant to medical imaging

Pressure ulcers (PUs) are defined as localised injuries to the skin and/or underlying tissue as a result of pressure or pressure together with shear. PUs present significant health implications to patients; costing billions to manage and/or treat. The burden of PU prevention in hospitals must be the concern of all healthcare professionals, including radiographers. The purpose of this narrative review article was to identify and critically evaluate relevant literature and research conducted into pressure ulcers (PUs) relevant to medical imaging. It is expected that this review article will increase the level of awareness about PUs amongst radiographers and help to develop appropriate interventions to minimise the risk of PUs. A literature search was conducted in PubMed/Medline, Scopus, CINAHL, and Google Scholar to retrieve relevant articles. Also, books, professional body guidelines, magazines, grey and unpublished literatures were also searched. The search was limited to English Language articles. Only five articles were retrieved and reviewed. There are limited studies on PUs relevant to medical imaging. Available studies provide some evidence that radiographic procedures and settings subject patients attending for radiographic procedures to the risk of PUs. Further studies are needed into PU risk assessment, minimisation and management in medical imaging to help raise awareness and address the problem of the potential for PU development.

Biotechnologies toward Mitigating, Curing, and Ultimately Preventing Edema through Compression Therapy

For a century-old problem, edema and its treatment have gone remarkably unnoticed by the biomedical community. Given the prevalence of lymphedema and its debilitating repercussions, there is an acute need for both efficacy-based measures and clinical standards to guide compression garment design and therapeutic application. This review outlines the current state of the art in compression treatment and suggests an integrated biomedical engineering approach going forward. Characterizing the pressure gradient profiles of commercial compression sleeves is necessary to better understand the role of compression treatment in the mitigation of swelling. Integration of pressure sensor technologies with advanced materials design and manufacture provides a critical path not only to elucidate the mechanisms of but also to improve on current compression-based therapies and associated therapeutic devices.

Techniques for Interface Stress Measurements within Prosthetic Sockets of Transtibial Amputees: A Review of the Past 50 Years of Research

The distribution of interface stresses between the residual limb and prosthetic socket of a transtibial amputee has been considered as a direct indicator of the socket quality fit and comfort. Therefore, researchers have been very interested in quantifying these interface stresses in order to evaluate the extent of any potential damage caused by the socket to the residual limb tissues. During the past 50 years a variety of measurement techniques have been employed in an effort to identify sites of excessive stresses which may lead to skin breakdown, compare stress distributions in various socket designs, and evaluate interface cushioning and suspension systems, among others. The outcomes of such measurement techniques have contributed to improving the design and fitting of transtibial sockets. This article aims to review the operating principles, advantages, and disadvantages of conventional and emerging techniques used for interface stress measurements inside transtibial sockets. It also reviews and discusses the evolution of different socket concepts and interface stress investigations conducted in the past five decades, providing valuable insights into the latest trends in socket designs and the crucial considerations for effective stress measurement tools that lead to a functional prosthetic socket.

Measurement of Lower Leg Compression In Vivo: Recommendations for the Performance of Measurements of Interface Pressure and Stiffness

BACKGROUND

Interface pressure and stiffness characterizing the elastic properties of the material are the parameters determining the dosage of compression treatment and should therefore be measured in future clinical trials.

OBJECTIVE

To provide some recommendations regarding the use of suitable methods for this indication.

METHOD

This article was formulated based on the results of an international consensus meeting between a group of medical experts and representatives from the industry held in January 2005 in Vienna, Austria.

RESULTS

Proposals are made concerning methods for measuring the interface pressure and for assessing the stiffness of a compression device in an individual patient.

CONCLUSIONS

In vivo measurement of interface pressure is encouraged when clinical and experimental outcomes of compression treatment are to be evaluated.

Auflagedruckmessung in der Dekubitusbehandlung

BACKGROUND

Pressure relief is an important factor to determine the quality of anti-decubitus devices. Many studies have been carried out to measure the interface pressure, but because the results differed markedly, we made a study to assess the measurement devices.

METHODS

The systems FSA, a device for internal use in the Lück company, the X-Sensor and an invasive subcutaneous pressure measurement over the os-sacrum (COACH: piezoelectric probe, MIPM) were tested on 20 healthy volunteers (average age 27 years, average BMI 21.8).

RESULTS

The values of interface measurement showed obvious deviations from subcutaneous pressure in two cases (FSA +1.8%, Lück -33%, X-Sensor +65%) and some results showed extreme variations (FSA +18 mmHg, Lück -21 mmHg, X-Sensor +27 mmHg).

CONCLUSIONS

The interface pressure measurement (with a few volunteers) is not suitable for a correct assessment of anti-decubitus devices. Furthermore, the use of this method is not necessary to monitor pressure relief in intensive care patients. These systems can, however be useful in the training of nursing staff.

The role of education, technique and equipment in pressure area care

This paper aims to reflect on the successful management of pressure ulcer equipment within a district general hospital. Insight is given into what is considered an effective, efficient and economic use of static and dynamic mattress, underpinned by a fundamental education package into pressure ulcer management and prevention techniques.

Evaluation of pressure ulcer prevention devices: a critical review of the literature

There is a wide range of pressure ulcer prevention devices, but little guidance on clinical and cost-effectiveness. This paper reviews the literature and demonstrates that approaches to evaluation are clinically and experimentally flawed.

Impact of Sitting Time on Seat-Interface Pressure and on Pressure Mapping With Multiple Sclerosis Patients

OBJECTIVE

To examine changes in seat-interface pressure with multiple sclerosis (MS) patients.

DESIGN

Case series.

SETTING

Multiple Sclerosis Society's Resource Centre and community.

PARTICIPANTS

Convenience sample of 15 MS wheelchair users and 12 MS non-wheelchair users.

INTERVENTION

Interface pressure was measured for 8 minutes using the Force Sensing Array pressure mapping system.

MAIN OUTCOME MEASURES

Number of activated sensors, standard deviation, average and maximum pressures.

RESULTS

With the wheelchair users, significant decreases were found in the standard deviation and average and maximum pressures during 0 to 2 minutes of sitting ( P <.01). Average pressure was the only parameter to show a significant decrease in the non-wheelchair users ( P <.01) during 0 to 2 minutes. Significant increases were found in all output parameters during 2 to 4 minutes with both groups ( P <.05). Non-wheelchair users showed no significant changes in the output parameters after 4 minutes, but wheelchair users showed significant continued increases in the output parameters from 4 to 8 minutes ( P <.05).

CONCLUSIONS

Because no significant changes in interface pressure occurred after 4 minutes of sitting with the non-wheelchair users, 4 minutes may be a reasonable sitting time before interface pressure is recorded with this group. Significant changes in interface pressure continued up to 8 minutes with the wheelchair users, therefore 8 minutes or beyond may be a reasonable sitting time before recording with this group.

Measuring interface pressure: validity and reliability problems

Health service providers rely on pressure-relieving and pressure-reducing products to prevent pressure ulcers. This review critically examines interface pressure measurements, most commonly used to evaluate patient support surfaces.

What can we learn from interface pressure measurements?

Interface pressure measurements are imprecise and subject to many variables. When selecting pressure support systems, it is best to take these into account along with other important factors.