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Biomedical subjects

M Ferguson-Pell

Publications and source records attributed to M Ferguson-Pell.

11 recordsLinked to original sources
PubMed2003

Evaluation of mattresses using interface pressure mapping.

OBJECTIVE: To compare the ranking of mattresses using several different performance indices, calculated from interface pressure-mapping data. METHOD: Five mattresses were compared using interface pressure-mapping on 10 healthy volunteers. Mattresses were ranked in order, on the basis of several different specified performance indices. RESULTS: Different performance indices ranked the mattresses in different orders. CONCLUSION: Elaborate performance indices should be used with care, since it is possible to construct a 'tailor-made' performance index to make any chosen mattress rank as the best. Care should be taken to ensure that a performance index is validated, preferably by some demonstrated link to clinical outcomes.

Aged↗
PubMed2000

Evaluation of a sensor for low interface pressure applications.

An ultra-thin, small sensor has recently been developed, "FlexiForce" (Tekscan, Boston, MA, USA), which may be effective for the measurement of low interface pressure between the skin, support surfaces and pressure garments. To evaluate the suitability of the sensor for these applications, drift, repeatability, linearity, hysteresis and curvature effects were tested under laboratory conditions. The drift was 1.7-2.5%/logarithmic time, the repeatability was 2.3-6.6% and the linearity was 1.9-9.9% in the range of forces of 10-50 g applied. The hysteresis was 5.4% on average. The output offset of the sensor increased with decreasing radius of curvature for radii less than 32 mm compared with a flat surface when no pressure was applied. The sensitivity to pressure decreased with curvature for radii less than 32 mm. It was found that the sensor had acceptable drift, repeatability, linearity and hysteresis. However, a significant curvature effect was observed indicating that the sensor is suitable for direct measurement on surfaces with the radii greater than 32 mm under static conditions.

Bandages↗
PubMed1995

An empirical technique to compensate for melanin when monitoring skin microcirculation using reflectance spectrophotometry.

Errors can occur in measuring blood content and oxygenation in subjects with significant skin pigmentation using reflectance spectrophotometry. The melanin in the epidermis not only reduces the amount of back-scattered light, but also has a characteristic absorption spectrum that varies between individuals. Skin color is primarily influenced by the concentration of melanin, blood content and oxygenation in the superficial microvasculature. A three-step process was developed empirically to accommodate the effect of melanin in the absorption spectrum of skin. A melanin index was developed and applied for each individual tested. Spectral components attributable specifically to melanin were subtracted from the measured spectrum, and its amplitude was normalized. This technique was tested with 26 able-bodied subjects with different levels of skin pigmentation. The melanin-compensated spectra from pigmented and caucasian skin were indistinguishable and no correlation was found between calculated values for indices of blood content and oxygenation, and melanin index.

Algorithms↗
PubMed1994

Assessment of skin blood content and oxygenation in spinal cord injured subjects during reactive hyperemia.

This study was undertaken to determine whether the reactive hyperemia response following ischemia in spinal cord injured (SCI) individuals is different from that which occurs in able-bodied (AB) individuals. The reactive hyperemia response was produced by applying a pressure of 150 mmHg for 300 s, 600 s, and 900 s to the skin over the greater trochanter in 10 SCI and 10 AB subjects using a computer-controlled pneumatic indentation system. The changes in blood content and oxygenation in the superficial vessels of the skin, associated with indentation, were monitored using reflectance spectrophotometry. A brief pressure of 80 mmHg, to simulate finger pressing (blanching), was applied to the same site to detect changes in reflow behavior during the hyperemic period. The results indicate that the reactive hyperemia response in SCI group was not substantially different from AB group although the reflow rate after load release was slower in the SCI group compared with the AB group.

Adult↗
PubMed1994

A skin indentation system using a pneumatic bellows.

A pneumatic indentation system using a copper bellows has been developed for physiological studies where a controlled uniaxial compressive force is required to be applied to the surface of the skin. Such a system is useful for studies where the physiological response of the tissues is to be monitored following a known loading history. The indentation system is driven by a vacuum/compression pneumatic pump through solenoid valves under closed-loop computer control. A load cell placed between the indentor and bellows monitors the applied force providing a feedback signal to the computer. The signal from the computer activates the valves supplying air pressure to the bellows, and the applied force is controlled using a digital closed-loop protocol. This system can be used to provide a controlled loading sequence to the skin without utilizing gravitational forces, which allows the subject to keep a more natural position during the experiment.

Equipment Design↗
PubMed1993

Prototype development and comparative evaluation of wheelchair pressure mapping system.

Wheelchair pressure mapping devices used in the prescription of seat cushions and postural supports have been limited in durability, data presentation, and/or clinical efficiency. This project sought to establish the ideal specifications for clinically useful pressure mapping systems, and to use these specifications to influence the design of an innovative wheelchair pressure mapping system (Tekscan "Seat"). Technology, previously developed for measurement of forces of dental occlusion and of the foot during gait, was applied to wheelchair seat mapping. Tests were designed to compare the performance of three pressure mapping systems: the Tekscan system, the FSA system, and the Talley TPM3. Bench tests were done to measure reproducibility, hysteresis, and creep of each of the pressure mapping systems. A contoured loader gauge was developed to test for the influence of hammocking. Tests were also performed using spinal cord-injured subjects to demonstrate the relative performance of the pressure mapping systems in a clinical setting. A focus group session was conducted with seating specialists to review the strengths and weakness of the systems for routine clinical use. The TPM3 was found to be the most accurate, stable, and reproducible but limited in ease of use, speed, and data presentation. FSA was rated well in clinical application and data management but demonstrated a pronounced hysteresis (+/-19%) and creep (4%). The Tekscan system also showed substantial hysteresis (+/-20%) and creep (19%) but was preferred by clinicians for its real-time display capabilities, resolution, and display options. Some trends in system performance on varied support surfaces were identified and can be a valuable guide to interpretation of measurements and prescription decision making in the clinic. Problems identified with the accuracy and stability of the Tekscan and FSA systems may be amenable to resolution with software correction and changes in fabrication. With these improvements all three systems show the potential to be useful clinical tools.

Consumer Behavior↗
PubMed1988

Biochemical changes in sweat following prolonged ischemia.

Much emphasis has been placed on the measurement of physical parameters at the body support interface in order to detect and moderate conditions which could result in pressure damage to soft tissues. Major difficulties are encountered both in the design of instrumentation and interpretation of the data collected. Metabolic processes in sweat glands that control sweat secretion have been shown to be sensitive to applied pressure, producing sweating rate suppression and changes in sweat NaCl concentration. In this study, we have demonstrated the feasibility of measuring lactate concentration in sweat collected locally using an electrochemical stimulation technique (iontophoresis of pilocarpine nitrate). Elevated levels of sweat lactate concentration during local tissue indentation were detected in a group of able-bodied subjects. Upon removal of the indentor, however, levels of sweat lactate returned to normal.

Adult↗
PubMed1986

Development of a modular wheelchair cushion for spinal cord injured persons.

This paper discusses a modular wheelchair cushion system intended for patients at moderate or low risk for developing pressure sores. With the use of components with different mechanical and physical properties the modular cushion produces improved performance compared with cushions comprising the individual components alone. In addition to achieving clinically acceptable interface pressures, this approach to wheelchair cushion prescription helps to accommodate individual preferences associated with stability, temperature dissipation, and resiliency. Mechanical tests were performed to demonstrate the underlying principles of the modular cushion. Tests with able-bodied subjects identified specific cushion configurations for different weight groups, offering alternative material configurations that may be selected at the discretion of the therapist or patient.

Body Weight↗
PubMed1983

Q-switched Ruby laser treatment of black tattoos.

The use of a Q-switched pulsed Ruby laser was studied in removing tattoos. The results were very satisfactory, but there are several major disadvantages which at present would probably preclude the use of this therapy on a routine basis.

Dermatologic Surgical Procedures↗
PubMed1980

Seating the disabled.

Explore the source record for details and available documents.

Persons with Disabilities↗