Stephen Sprigle

Pressure-related deep tissue injury under intact skin and the current pressure ulcer staging systems.

OBJECTIVETo identify how current pressure ulcer staging systems and experts describe pressure-related deep tissue injury under intact skin in the published research literature. DESIGNA systematic review of published English-language literature as of November 2002 with the words decubitus or pressure ulcer(s) in the title. Additional relevant articles were identified by National Pressure Ulcer Advisory Panel members and were included in the analysis. An expert commentary was developed by iterative review by the National Pressure Ulcer Advisory Panel members. MAIN OUTCOME MEASURESManuscripts were reviewed for staging systems cited or described, definitions of Stage I pressure ulcers, and descriptions or definitions of pressure-related deep tissue injury under intact skin. MAIN RESULTSNinety-four relevant articles were identified. Seventy-three articles (78%) described a staging system, and 55 of 73 (75%) cited the staging definitions from Shea, the National Pressure Ulcer Advisory Panel, or the Agency for Health Care Policy and Research. The National Pressure Ulcer Advisory Panels staging definitions were the most frequently cited overall. Twenty-three articles (25%) included some discussion that could be interpreted as relevant to the topic of pressure-related deep tissue injury under intact skin; however, no consistency in definitions of Stage I pressure ulcers or terminology for pressure-related deep tissue injury under intact skin was found. CONCLUSIONSSeveral pressure ulcer staging systems are frequently cited, but none define pressure-related deep tissue injury under intact skin. The National Pressure Ulcer Advisory Panel recommends using the terms “pressure-related deep tissue injury under intact skin” or “deep tissue injury under intact skin” for describing these lesions and encourages investigators to establish the epidemiology and natural history of these lesions.

Assessing Evidence Supporting Redistribution of Pressure for Pressure Ulcer Prevention: A Review

The formation and underlying causes of pressure ulcers (PUs) are quite complex, with multiple influencing factors. However, by definition pressure ulcers cannot form without loading, or pressure, on tissue. Clinical interventions typically target the magnitude and/or duration of loading. Pressure magnitude is managed by the selection of support surfaces and postural supports as well as body posture on supporting surfaces. Duration is addressed via turning and weight shifting frequency as well as with the use of dynamic surfaces that actively redistribute pressure on the body surfaces. This article shows that preventative interventions must be targeted to both magnitude and duration and addresses the rationale behind several common clinical interventions--some with more scientific evidence than others.

Reduction of sitting pressures with custom contoured cushions.

Previous research indicated that matching a cushion to the shape of the buttocks results in less tissue distortion and lower interface pressures. A system was developed to measure body contours and fabricate a cushion to match the measured contour. This project fabricated contoured foam cushions for 11 persons with spinal cord lesions (C5-L3). Mean pressures were compared on two flat and two contoured foams with different degrees of stiffness. Deflection characteristics on flat foam were compared to deflection on contoured foam in order to analyze loading differences. Material studies were determined by examining the load-deflection curves for flat foams of 1-, 2-, and 3-inch thicknesses. It was found that sitting on contoured foam resulted in a lower pressure distribution than sitting on flat foam (p less than 0.05), and sitting on a soft foam (ILD = 45) resulted in a lower pressure distribution than sitting on a stiffer foam (ILD = 55) (p less than 0.05). Results of the deflection measurements and compression tests were used to explain the loading differences at the seat interface of flat and contoured cushions. Loaded contoured foam demonstrated increased enveloping of the buttocks, decreased foam compression, and a more uniform pressure distribution. These attributes are typical of a safer sitting surface and may indicate less tissue distortion.

Reliability of bench tests of interface pressure.

Determination of an appropriate wheelchair cushion to optimize loading on buttock tissue is crucial to pressure ulcer prevention. Standardized test methods aim to simplify selection by helping clinicians and users identify a class or category of cushions that will meet the important medical need of adequate pressure distribution. The objective of this project was to determine the test-retest reliability of interface pressure measurements taken using bench tests as opposed to human subject tests. Ten wheelchair cushions were tested following the methods for interface pressure measurement as defined in a draft International Organization for Standardization document. Dispersion index, contact area, percent force in the ischial regions, peak pressure index, and seating pressure index–standard deviation are reliable measures. Average pressure is reliable but not very volatile between cushions. The data also indicate that peak pressure, seating pressure index–skew (SPI-sk), and the other five percent force regions are not reliable. Certain bench interface pressure variables were found to have adequate intralaboratory repeatability. Interlaboratory reliability must also be tested. If a bench interface pressure test is used to indicate cushion performance, its validity should also be studied. Research is underway to relate interface pressure variables to clinical measurements of wheelchair users. Once validity is shown, standardized test results can then be used by clinicians to simplify and improve the wheelchair cushion selection process.

Clinical skin temperature measurement to predict incipient pressure ulcers.

OBJECTIVE To evaluate temperature differences between areas of erythema and surrounding healthy tissue to determine whether clinical temperature measurement of sites at risk for pressure ulcer development could be used to indicate tissue damage. To validate the temperature portion of the National Pressure Ulcer Advisory Panels new Stage I pressure ulcer definition. DESIGN Repeated measures design. SETTING Acute rehabilitation hospital. SUBJECTS 65 outpatients and inpatients presenting with pressure-induced erythema at areas at risk for pressure ulcer development. The subjects were primarily non-ambulatory and exhibited a range of skin pigmentation and disabilities, including spinal injury, multiple sclerosis, and lower-limb amputations. MAIN RESULTS The temperature and appearance of 80 pairs of erythematic and control sites were documented. Sites were considered to have equal temperatures if the difference was within plus or minus 1.0 degree F. Fifteen percent (n = 12) of the erythematic sites were the same temperature as the surrounding tissue, 23% (n = 18) of the erythematic sites were cooler than the control sites, and 63% (n = 50) were warmer. CONCLUSION Both increased and decreased temperature differences can be used to indicate reactive hyperemia or a Stage I pressure ulcer, but a tissue integrity problem may still exist despite the absence of a temperature difference.

Validation of an accelerometer-based method to measure the use of manual wheelchairs

The goal of this project was to develop and validate a methodology for measuring manual wheelchair movement. The ability to study wheelchair movement is necessary across a number of clinical and research topics in rehabilitation, including the outcomes of rehabilitation interventions, the long-term effects of wheelchair propulsion on shoulder health, and improved wheelchair prescription and design. This study used a wheel-mounted accelerometer to continuously measure distance wheeled, and to continuously determine if the wheelchair is moving. Validation of the system and algorithm was tested across typical mobility-related activities of daily living, which included short slow movements with frequent starts, stops, and turns, and straight, steady state propulsion. Accuracy was found to be greater than 90% across wheelchair and wheel types (spoke and mag), propulsion techniques (manual and foot), speeds, and everyday mobility-related activities of daily living. Although a number of approaches for wheelchair monitoring are currently present in the literature, many are limited in the data they provide. The methodology presented in this paper can be applied to a variety of commercially available products that record bi-axial accelerations, and used to answer many research questions in wheeled mobility.

Load Redistribution in Variable Position Wheelchairs in People With Spinal Cord Injury

Abstract Background/Objective: Tilt and recline variable position seating systems are most commonly used for pressure relief to decrease potential for skin breakdown. This study provides quantitative information on the magnitudes of loading on the seat and back during phases of tilt, recline, and standing. The objective of this study was to show that the amount of force reduction at the seat would differ across these 3 methods within their respective clinical ranges. Participants: Six able-bodied (AB) subjects (2 men, 4 women) with a median age of 25 years, and 10 subjects (8 men, 2 women) with spinal cord injury (SCI) with a median age of 35.5 years. Methods: Subjects sat on a power wheelchair with Tekscan pressure mats placed underneath a foam backrest and cushion. Data were collected at 5 positions for each method. Order of position and method tested were randomized. Linear regressions were used to calculate the relationships of normalized seat and backrest forces to seat and backrest angles for each chair configuration. Results: Normalized seat loads had strong linear relationships with the angles of change in tilt, recline, and standing for both groups. Maximum decreases in seat load occurred at full standing and full recline in the SCI subjects and in full standing in the AB subjects. Loads linearly increased on the back during tilt and recline and linearly decreased during standing for both groups. Conclusions: Standing and recline offered similar seat load reductions at their respective terminal positions. Standing also reduced loading on the backrest. Recognizing that each method had clinical benefits and drawbacks, the results of this study indicate that tilt, recline, and standing systems should be considered as a means of weight shifting for wheelchair users.

Effect of model design, cushion construction, and interface pressure mats on interface pressure and immersion

Measuring interface pressure (IP) is one way to characterize cushion performance in the clinic and laboratory. This study explored how the presence of four commercially available IP mats affected IP on and immersion of two buttocks models. We loaded seven cushions with each buttocks model and captured pressure data using FSA sensors (Vista Medical Ltd; Winnipeg, Manitoba, Canada). Analysis was performed to compare pressure magnitude and immersion. Overall, both pressure magnitude and immersion changed after mat introduction. A significant interaction existed between cushion and mat condition and cushion and model for all variables. Introducing an IP mat to the model-cushion interface alters the loading on the cushion. The mats bridged the contours of the model, causing a change in IP at the locations studied. Although immersion was statistically different between mat conditions, the magnitude of the difference was less than 1 mm once we accounted for the thickness of the mats. The significance of the cushion-mat interaction indicates that the mat effect differed across cushion design. Clinical and research users of pressure mats should consider the effect of mat presence, the effect of model design, and mat and buttocks interactions with cushions for successful use.

Development and testing of a pelvic goniometer designed to measure pelvic tilt and hip flexion

OBJECTIVE To determine the reliability and validity of a pelvic goniometer designed to measure the pelvic tilt and hip flexion during seated posture. BACKGROUND Assessment of the seated posture requires measurement of the pelvis and hip. Determining accurate pelvic tilt and hip flexion angles during sitting is often difficult using standard techniques. A pelvic goniometer has been designed to measure pelvic tilt and hip flexion angle of persons in a seated posture. METHODS VALIDATION of the pelvic goniometer was done radiographically. Ten male volunteers sat in three postures--erect, forward or anterior tilt, and posterior tilt. Pelvic tilt and hip angle were recorded using radiographs and the pelvic goniometer. Reliability of pelvic and conventional goniometers was done using seated nondisabled subjects with physical therapists performing measurements. RESULTS VALIDATION the average differences and correlation between the pelvic goniometer and radiographic measures were as follows--pelvic tilt: -4.9 degrees, 0.93; hip angle 1.2 degrees, 0.81. Reliability: average range of hip angle across three measures was about 3 degrees for both goniometers. CONCLUSIONS The data indicate that the pelvic goniometer has utility in measuring pelvic tilt and hip angle, especially within the seated posture. Because it measures both pelvic tilt and hip angle, the pelvic goniometer has an advantage over conventional goniometers that only measure the latter. RELEVANCE A valid and reliable tool that measures pelvic tilt and hip angle of persons in a seated posture is needed for clinical research and practice. Its applications include wheelchair seating evaluations and ergonomic assessments of seated workers.

The Participation and Activity Measurement System: An example application among people who use wheeled mobility devices

Purpose. To present the Participation and Activity Measurement System (PAMS), a system designed to examine activity and participation among people who use wheeled mobility devices. Methods. Description of PAMS’ components and an example of its application among people who use tilt-in-space wheelchairs. Results. PAMS combines objective and subjective descriptions of mobility-based activities within a persons home and community. By applying technologies such as wheel revolution counters, seat occupancy sensors and global positioning systems, PAMS captures diverse metrics of wheelchair use including destinations, wheeled distance, duration of occupancy and the use of specialised features such as tilt. These metrics also provide the basis for a prompted recall interview designed to elicit contextual data about wheelchair use within a persons home and community. A recent study among people who use tilt-in-space wheelchairs demonstrates the components and application of PAMS. Conclusions. The combination of objective and subjective data afforded by the application of PAMS reflects a complex relationship between wheelchair use and the role of mobility as people go about their daily home and community activities. PAMS can be adapted to a variety of research questions and may be used as an alternative or supplement to self-report assessments of activity and participation.