Effects of simulated aging on cushion performance measured using standardized laboratory test methods.

Standardized test methods providing wheelchair cushion performance characteristics can aid cushion design and selection. Assessment of the changes in performance that occur with aging provides additional information. Test methods published by the International Organization for Standardization were applied to a cohort of 21 cushions of varying design and construct to assess changes in performance due to simulated aging. Performance tests measured immersion, envelopment, stiffness, impact response, and pressure distribution properties. Means of test outcome metrics pre- and post-aging are presented, and changes in the metrics due to aging are analyzed using linear mixed models. Statistically significant changes were found for outcome measures for each performance test. The minimum aging method simulating 18-24 months use had a significant effect on cushion performance. Changes to loaded contour depth, envelopment, pressure mapping, hysteresis, horizontal stiffness, and 10% force deflection characterization test metrics indicated decreased cushion performance. The simulated aging method resulted in cushion stiffening and reduced immersion, pressure distribution, and stability performance. Together, these changes may increase a user's risk for pressure injuries.

Development of a Wheelchair Repair Registry.

OBJECTIVE: To describe the development of a wheelchair repair registry from large datasets to attain an understanding of wheelchair failures and service repairs. DESIGN: Guidelines for registry development were applied and anchored around Labor-Tracker, a web-based information management system for wheelchair suppliers to manage and track wheelchair repairs. The registry was designed using online analytical processing, allowing for rapid data queries from multiple dimensions that enable complex data analysis and discovery. SETTING: The Wheelchair Repair Registry (WRR) was developed through an industry and academic collaboration whereby repair data were collected in the field, entered into the Labor-Tracker system, deidentified, and then transferred to the registry and made available for analyses. PARTICIPANTS: Wheelchair supplier service technicians reported data from repair services provided to individuals who use power wheelchairs, manual wheelchairs, and scooters. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Wheelchair failure and repair data, including variables related to scheduling, equipment information (eg, manufacturer, model, serial number, purchase date), labor, parts, and reasons for repairs. RESULTS: The WRR was developed to analyze wheelchair repairs and failures from the Labor-Tracker system. Currently, the registry has more than 60,000 repairs conducted on more than 5000 wheelchair devices from 25 manufacturers. The devices include 60% power wheelchairs, 35% manual wheelchairs, and 5% scooters. CONCLUSIONS: The WWR creates opportunities to apply large-data analytical methodologies that will serve to inform quality standards, practice, equipment selection, preventative maintenance routines, product design, and policy.

Preliminary steps of the development of a Minimum Uniform Dataset applicable to the international wheelchair sector.

Assistive products outcomes are needed globally to inform policy, practice, and drive investment. The International Society of Wheelchair Professionals developed a Minimum Uniform Dataset (MUD) for wheelchair services worldwide with the intent to gather data that is comparable globally. The MUD was developed with the participation of members from around the globe and its feasibility piloted at 3 sites. Three versions of the MUD are now available-a short form with 29 data points (available in English, Spanish, and French) and a standard version with 38 data points in English. Future work is to validate and complete the translation cycles followed by promoting the use of the MUD globally so that the data can be leveraged to inform policy, practice and direct investments.

Implementing local cooling to increase skin tolerance to ischemia during normal seating in people with spinal cord injury.

The purpose of this study was to investigate the effectiveness of local cooling in reducing reactive hyperemia after ischemia at the ischial tuberosities for people with spinal cord injury (SCI) during normal seating. The degree of the reactive hyperemic response is indicative of the extent of cellular stress caused by the ischemia. We hypothesized that reactive hyperemic skin blood flow (SBF) responses will be lower when local cooling is implemented by the wheelchair seat cushion. This study used a repeated measures design, and each subject underwent two conditions: normal seating with temperature control 'on' (cooling) and 'off' (non-cooling) for 30 min. Twenty-three participants with traumatic SCI were recruited. SBF and skin temperature were collected before, during and after seating. SBF signals were processed with short-time Fourier analyses to examine the underlying vascular control mechanisms, including the following (corresponding frequency bands): metabolic (0.0095-0.02 Hz), neurogenic (0.02-0.05 Hz), and myogenic (0.05-0.15 Hz) spectral densities. Our results showed that with cooling, skin temperature decreased (range -0.4 ~ -3.1 °C, p = 0.002), and reactive hyperemia parameters (normalized peak SBF and perfusion area) were reduced (p = 0.02, p = 0.033, respectively). In addition, changes in normalized peak SBF (non-cooling - cooling) was moderately correlated with changes in normalized metabolic and neurogenic spectral densities. Our findings suggested that local cooling has a positive effect on reducing the cellular stress caused by ischemia during normal seating. Metabolic and neurogenic SBF control mechanisms may play a minor role. Further exploration of the effect of temperature control on pressure injury prevention is warranted.

Sacral skin blood flow response to alternating pressure operating room overlay.

Pressure injuries resulting from long surgeries may be caused by prolonged ischemia. Operating table surfaces with alternating pressure (AP) features may reduce the risk of ischemia-induced pressure injuries by providing periodic relief of blood flow occlusions. Prior research investigated alternating loading applied with a single isolated rigid indenter and demonstrated increased perfusion. This study quantified effects of an overlay with AP on sacral skin perfusion for individuals lying supine for 60-min while blood flow was monitored. The mean normalized sacral skin blood flow was found to be greater with the AP overlay over an operating table pad compared to the operating pad alone (pad with AP mean SBF = 1.45 ±â€¯1.16, pad without AP mean SBF = 1.03 ±â€¯0.46, p = 0.10). Peak and average interface pressure at the sacrum was significantly lower during the deflation cycle of the AP surface compared to the operating pad alone (P < 0.001), suggesting this periodic reduction resulted in higher mean blood flow. Post-hoc regression analysis showed participant body mass index was a significant predictor of the effectiveness of the AP overlay (p = 0.012). The results suggest risk for pressure injuries due to prolonged ischemia might be mitigated by the addition of an alternating pressure feature on operating table pads for lower BMI patients.

Detection and classification methodology for movements in the bed that supports continuous pressure injury risk assessment and repositioning compliance.

Pressure injuries are costly to the healthcare system and mostly preventable, yet incidence rates remain high. Recommendations for improved care and prevention of pressure injuries from the Joint Commission revolve around continuous monitoring of prevention protocols and prompts for the care team. The E-scale is a bed weight monitoring system with load cells placed under the legs of a bed. This study investigated the feasibility of the E-scale system for detecting and classifying movements in bed which are relevant for pressure injury risk assessment using a threshold-based detection algorithm and a K-nearest neighbor classification approach. The E-scale was able to detect and classify four types of movements (rolls, turns in place, extremity movements and assisted turns) with >94% accuracy. This analysis showed that the E-scale could be used to monitor movements in bed, which could be used to prompt the care team when interventions are needed and support research investigating the effectiveness of care plans.

A Randomized Clinical Trial of Wheeled Mobility for Pressure Injury Prevention and Better Function.

OBJECTIVES: To evaluate the effectiveness of wheelchair assessment and configuration on pressure injury incidence, mobility, and functioning in a wheelchair. DESIGN: Randomized controlled trial with participants individually randomized into intervention and control groups. SETTING: Nursing home. PARTICIPANTS: Nursing home residents aged 60 and older who used wheelchairs and were at risk for pressure injuries (N=258). INTERVENTION: Treatment and evaluation, individually configured wheelchair and skin protection cushion; control and evaluation, facility-provided wheelchair and skin protection cushion. MEASUREMENTS: Pressure injury incidence, Nursing Home Life Space Diameter score, Functioning Every Day in a Wheelchair-Capacity (FEW-C) score, and Wheelchair Skills Test (WST) score. RESULTS: No differences in pressure injuries (p=.77) were found. Pelvic rotation (odds ratio (OR)=0.15, 95% confidence interval (CI)=0.03-0.70, p=.02) and Day 14 WST skill score (OR=0.74, 95% CI=0.60-0.91, p=.004) were significant predictors of pressure injuries. Significant differences were observed between groups in change in FEW-C independence scores between before randomization and endpoint (p=.03) and before randomization and 14 days (p=.04). CONCLUSION: Participants with individually configured wheelchairs improved more in the safe and effective use of their wheelchairs than residents with facility-provided wheelchairs. The outcomes indicated that nursing home residents functioned safely at a higher level in their wheelchairs if their devices were individually configured using a comprehensive wheelchair and seating assessment process. There was no difference in the incidence of pressure injuries between the two groups. TRIAL REGISTRATION: NCT01275313.

An MRI investigation of the effects of user anatomy and wheelchair cushion type on tissue deformation.

AIM OF THE STUDY: Tissue deformation is recognized as an important risk factor for pressure injuries. This study investigated the effects of anatomy and wheelchair cushion type on tissue deformation. MATERIALS AND METHODS: Direct 3-dimensional tissue deformation response was measured for six participants sitting on six different wheelchair cushions using MR imaging. Two participants had a traumatic spinal cord injury (SCI) within one year of the assessment, two sustained traumatic SCI at least 13 years prior, and two were without SCI. Tissue deformation was quantified using the difference in volume of tissue beneath the ischial tuberosity (IT) between unloaded and loaded (sitting) conditions. RESULTS: The participants with SCI tended to have less muscle tissue volume beneath their ITs while sitting compared to participants without SCI. Reductions in muscle and fat volumes in the loaded conditions varied depending on both cushion and participant. Higher interface pressures tended to be associated with lower unloaded tissue thicknesses. CONCLUSION: The study showed no single cushion type tested produced the lowest amount of tissue deformation across all participants. Individual anatomy and cushion type affect deformation response of tissue and related pressure injury risk.

How a diverse research ecosystem has generated new rehabilitation technologies: Review of NIDILRR's Rehabilitation Engineering Research Centers.

Over 50 million United States citizens (1 in 6 people in the US) have a developmental, acquired, or degenerative disability. The average US citizen can expect to live 20% of his or her life with a disability. Rehabilitation technologies play a major role in improving the quality of life for people with a disability, yet widespread and highly challenging needs remain. Within the US, a major effort aimed at the creation and evaluation of rehabilitation technology has been the Rehabilitation Engineering Research Centers (RERCs) sponsored by the National Institute on Disability, Independent Living, and Rehabilitation Research. As envisioned at their conception by a panel of the National Academy of Science in 1970, these centers were intended to take a "total approach to rehabilitation", combining medicine, engineering, and related science, to improve the quality of life of individuals with a disability. Here, we review the scope, achievements, and ongoing projects of an unbiased sample of 19 currently active or recently terminated RERCs. Specifically, for each center, we briefly explain the needs it targets, summarize key historical advances, identify emerging innovations, and consider future directions. Our assessment from this review is that the RERC program indeed involves a multidisciplinary approach, with 36 professional fields involved, although 70% of research and development staff are in engineering fields, 23% in clinical fields, and only 7% in basic science fields; significantly, 11% of the professional staff have a disability related to their research. We observe that the RERC program has substantially diversified the scope of its work since the 1970's, addressing more types of disabilities using more technologies, and, in particular, often now focusing on information technologies. RERC work also now often views users as integrated into an interdependent society through technologies that both people with and without disabilities co-use (such as the internet, wireless communication, and architecture). In addition, RERC research has evolved to view users as able at improving outcomes through learning, exercise, and plasticity (rather than being static), which can be optimally timed. We provide examples of rehabilitation technology innovation produced by the RERCs that illustrate this increasingly diversifying scope and evolving perspective. We conclude by discussing growth opportunities and possible future directions of the RERC program.

Inflammatory Mediators Associated With Pressure Ulcer Development in Individuals With Pneumonia After Traumatic Spinal Cord Injury: A Pilot Study.

OBJECTIVE: To identify the inflammatory mediators around the time of pneumonia onset associated with concurrent or later onset of pressure ulcers (PUs). DESIGN: Retrospective. SETTING: Acute hospitalization and inpatient rehabilitation unit of a university medical center. PARTICIPANTS: Individuals (N=86) with traumatic spinal cord injury (SCI) were included in the initial analyses. Fifteen of the 86 developed pneumonia and had inflammatory mediator data available. Of these 15, 7 developed PUs and 8 did not. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Twenty-three inflammatory mediators in plasma and urine were assayed. The differences in concentrations of plasma and urine inflammatory mediators between the closest time point before and after the diagnosis of pneumonia were calculated. RESULTS: Initial chi-square analysis revealed a significant (P=.02) association between pneumonia and PUs. Individuals with SCI and diagnosed pneumonia had nearly double the risk for developing PUs compared with those with no pneumonia. In individuals with pneumonia, Mann-Whitney U exact tests suggested an association (P<.05) between the formation of a first PU and a slight increase in plasma concentrations of tumor necrosis factor-alpha (TNF-α), and a decrease in urine concentrations of TNF-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin (IL)-15 after onset of pneumonia. CONCLUSIONS: These findings suggest that a relatively small increase in plasma TNF-α, and decreases in urine TNF-α, GM-CSF, and IL-15 from just before to just after the diagnosis of pneumonia could be markers for an increased risk of PUs in individuals with pneumonia after traumatic SCI.

Association between presence of pneumonia and pressure ulcer formation following traumatic spinal cord injury.

OBJECTIVE: To determine if the presence of pneumonia and pressure ulcers are associated in individuals with an acute spinal cord injury during acute care and rehabilitation hospitalizations. DESIGN: Retrospective, secondary analyses of data obtained from the Spinal Cord Injury Model Systems enrolled from 1993 until 2006 Setting: Acute care hospitalization and inpatient rehabilitation facilities Participants: A cohort of individuals hospitalized in acute care (n = 3,098) and inpatient rehabilitation (n = 1,768) was included in the analysis. Frequencies of pressure ulcer formation and episodes of pneumonia were noted in both settings. INTERVENTIONS: Not applicable. OUTCOME MEASURES: Pressure ulcer formation and diagnosis of pneumonia Results: The development of pressure ulcers, including stage I, was 20.3% acute care and 21.1% during in inpatient rehabilitation. Multivariate logistic regression analyses revealed a significant association of pneumonia with occurrence of pressure ulcers (P ≤ 0.001, OR = 2.3 and 2.2 respectively), the American Spinal Injury Association Impairment Scale grades (P < 0.001), and utilization of mechanical ventilation (P < 0.01) in both settings. CONCLUSION: A higher presence of pressure ulcers was found in individuals with pneumonia, after adjusting for injury severity, age, sex, and utilization of mechanical ventilation. Impaired inflammatory response and decreased mobility in individuals with pneumonia may predispose these individuals to develop pressure ulcers. Surveillance and preventive measures for pressure ulcers should be rigorous in individuals with SCI and pneumonia.

Feasibility of freehand ultrasound to measure anatomical features associated with deep tissue injury risk.

Deep tissue injuries (DTI) are severe forms of pressure ulcers that start internally and are difficult to diagnose. Magnetic resonance imaging (MRI) is the currently preferred imaging modality to measure anatomical features associated with DTI, but is not a clinically feasible risk assessment tool. B-mode ultrasound (US) is proposed as a practical, alternative technology suitable for bedside or outpatient clinic use. The goal of this research was to confirm US as an imaging modality for acquiring measurements of anatomical features associated with DTI. Tissue thickness measurements using US were reliable (ICC=.948) and highly correlated with MRI measurements (muscle r=.988, p ≤ .001; adipose r=.894, p ≤ .001; total r=.919; p ≤ .001). US measures of muscle tissue thickness were 5.4mm (34.1%) higher than MRI, adipose tissue thickness measures were 1.6mm (11.9%) lower, and total tissue thickness measures were 3.8mm (12.8%) higher. Given the reliability and ability to identify high-risk anatomies, as well as the cost effectiveness and availability, US measurements show promise for use in future development of a patient-specific, bedside, biomechanical risk assessment tool to guide clinicians in appropriate interventions to prevent DTI.

Predictive validity of the Spinal Cord Injury Pressure Ulcer Scale (SCIPUS) in acute care and inpatient rehabilitation in individuals with traumatic spinal cord injury.

OBJECTIVE: To evaluate the validity of the Spinal Cord Injury Pressure Ulcer Scale (SCIPUS) during acute care and inpatient rehabilitation following spinal cord injury (SCI) by determining critical cutoff points and assessing the ability to predict risk for pressure ulceration (PrU). DESIGN: Retrospective. METHODS: Sensitivity, specificity, and area under the curve (AUC) for the receiver operating characteristic were determined for the scale's ability to predict PrU 2-3 and 5-7 days after administrating the SCIPUS during acute care, and 5-7 and 14-21 days after administrating the SCIPUS during inpatient rehabilitation. RESULTS: During acute hospitalization, SCIPUS's ability to assess risk for PrUs within 2-3 days was determined at cutoff score of 15 with 100% sensitivity and 75% specificity, AUC = 0.85. The scale was unable to assess PrU risk at 5-7 days, AUC < 0.6 at cutoff score of 13. During inpatient rehabilitation, the scale was unable to assess PrU risk at 5-7 and 14-21 days, AUC < 0.6 at cutoff score of 9. CONCLUSIONS: The SCIPUS could predict PrU occurring within 2-3 days following administration during acute, but unable to predict over a longer term within acute or inpatient rehabilitation. Improved PrU risk assessment following SCI may be possible with modification to the SCIPUS.

Early Detection of Pressure Ulcer Development Following Traumatic Spinal Cord Injury Using Inflammatory Mediators.

OBJECTIVE: To identify changes in concentrations of inflammatory mediators in plasma and urine after traumatic spinal cord injury (SCI) and before the occurrence of a first pressure ulcer. DESIGN: Retrospective; secondary analysis of existing data. SETTING: Acute hospitalization and inpatient rehabilitation sites at a university medical center. PARTICIPANTS: Individuals with a pressure ulcer and plasma samples (n=17) and individuals with a pressure ulcer and urine samples (n=15) were matched by age and plasma/urine sample days to individuals with SCI and no pressure ulcer (N=35). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Plasma and urine samples were assayed in patients with SCI, capturing samples within 4 days after the SCI to a week before the formation of the first pressure ulcer. The Wilcoxon signed-rank test was performed to identify changes in the inflammatory mediators between the 2 time points. RESULTS: An increase in concentration of the chemokine interferon-γ-induced protein of 10kd/CXCL10 in plasma (P<.01) and a decrease in concentration of the cytokine interferon-α in urine (P=.01) were observed before occurrence of a first pressure ulcer (∼4d) compared with matched controls. CONCLUSIONS: Altered levels of inflammatory mediators in plasma and urine may be associated with pressure ulcer development after traumatic SCI. These inflammatory mediators should be explored as possible biomarkers for identifying individuals at risk for pressure ulcer formation.

Relative contributions of interface pressure, shear stress, and temperature on ischemic-induced, skin-reactive hyperemia in healthy volunteers: a repeated measures laboratory study.

Although the primary risk factors for pressure ulcer development - pressure, shear, skin temperature, moisture, and friction - have been identified for decades, the relative contribution of each to this risk remains unclear. To confirm the results of and expand upon earlier research into the relative contributions of interface pressures, shear stress, and skin temperature among 4 healthy volunteers, a study involving 6 additional healthy 40- to 75-year-old volunteers was conducted and results of the 2 studies were pooled. All 3 variables (interface pressures, shear stress, and skin temperature) were systematically and randomly varied. In the prone position, volunteers each underwent 18 test conditions representing different combinations of temperature (28˚ C, 32˚ C, 36˚ C), pressure (8.0 and 13.3 kPa), and shear (0, 6.7, and 14.0 kPa) using a computer-controlled indenter applied to the sacrum for 20 minutes exerting weights of 100 g and 200 g to induce 0.98 N and 1.96 N of shear force, respectively. Each condition was tested twice, resulting in a total of 360 trials. Magnitude of postload reactive hyperemia as an index of ischemia was measured by laser Doppler flowmetry. Fixed effects regression models were used to predict 3 different indices of reactive hyperemic magnitude. Friedman tests were performed to compare the reactive hyperemia among 3 different skin temperatures or shear stresses under the same amount of localized pressure. In all regression models, pressure and temperature were highly significant predictors of the extent of reactive hyperemia (P <0.0001 and P <0.0001, respectively); the contributions of shear stress were not statistically significant (P = 0.149). With higher temperature, reactive hyperemia increased significantly, especially at greater localized pressure and shear stress, and the difference was more profound between 32˚ C and 36˚ C than between 28˚ C and 32˚ C. These results confirm that, in laboratory settings, temperature is an important factor in tissue ischemia. Additional studies examining the relative importance of pressure, shear, and temperature and potential effects of lowering temperature on tissue ischemia in healthy volunteers and patients at risk for pressure ulcer development are warranted. Because deformation at weight-bearing areas often results in blood flow occlusion, actively lowering the temperature may reduce the severity of ischemia and lower pressure ulcer risk. In this study, shear did not appear to contribute to ischemia in the dermal tissues when assessed using laser Doppler; further work is needed to examine its effect on deeper layers, particularly with regard to nonischemic mechanisms.

Effectiveness of local cooling for enhancing tissue ischemia tolerance in people with spinal cord injury.

OBJECTIVE: To investigate the effects of localized cooling and cooling rate on pressure-induced ischemia for people with and without neurological deficits. DESIGN: A 2 × 3 mixed factorial design with two groups: (1) people with spinal cord injury (SCI) and (2) people without neurological deficits (control), and three test conditions: (1) pressure only, (2) pressure with fast cooling (-4°C/min), and (3) pressure with slow cooling (-0.33°C/min). SETTING: University laboratory. PARTICIPANTS: Fourteen controls and 14 individuals with SCI. INTERVENTIONS: Pressure on the sacrum was 0.4 kPa for 5 minutes, then 8 kPa for 20 minutes, and finally 0.4 kPa for 15 minutes. Fast and slow cooling to 25°C applied during 8 kPa of pressure. OUTCOME MEASURES: Reactive hyperemia and its spectral densities in the metabolic, neurogenic, and myogenic frequency ranges. RESULTS: In controls, reactive hyperemia was greater in pressure only as compared with both cooling conditions. No change was noted in all spectral densities in both cooling conditions, and only neurogenic spectral density increased without cooling. In subjects with SCI, no difference was noted in reactive hyperemia among conditions. However, metabolic and myogenic spectral densities increased without cooling and all spectral densities increased with slow cooling. No change was noted in all spectral densities with fast cooling. CONCLUSION: Local cooling reduced the severity of ischemia in controls. This protective effect may be masked in subjects with SCI due to chronic microvascular changes; however, spectral analysis suggested local cooling may reduce metabolic vasodilation. These findings provide evidence towards the development of support surfaces with temperature control for weight-bearing soft tissues.

The relative contributions of interface pressure, shear stress, and temperature on tissue ischemia: a cross-sectional pilot study.

Tissue ischemia is thought to play a major role in the development of pressure ulcers. Pressure, shear, and temperature are acknowledged contributors, but the relative magnitude of each factor is largely unknown. A cross-sectional pilot study was conducted on the sacrums of four healthy volunteers to estimate the relative contributions of each variable by systematically varying and assessing the resulting level of ischemia in the skin tissue. Using a repeated measures design, 21 combinations of temperature (28˚C, 32˚C, and 36˚C); pressure (0 kPa, 8.0 kPa, and 13.3 kPa), corresponding to 0 mm Hg, 60 mm Hg, and 100 mm Hg; and shear stress (0 kPa, 6.7 kPa, and 14.0 kPa), corresponding to 0 mm Hg, 50 mm Hg, and 100 mm Hg (practical testing values), were tested twice, for a total of 168 trials. Using laser Doppler flowmetry, the magnitude of post-load reactive hyperemia was used as an index of ischemia. Fixed Effects and Ranks linear regression models were developed to predict three different indices of reactive hyperemic magnitude with pressure, shear stress, and temperature as the variables. Pressure and temperature were always highly significant predictors of the extent of reactive hyperemia (P <0.0001 for Perfusion Area, peak minus baseline blood flow, and Normalized Peak blood flow), and the contributions of shear stress were insignificant (P = 0.5351 for Perfusion Area, P = 0.6403 for Peak minus Baseline blood flow, and P = 0.8941 for Normalized Peak blood flow). Depending upon the model, comparison of coefficients suggested that an increase of 1.0˚C contributes as much to reactive hyperemia in the skin as 12 mm Hg to 15 mm Hg of interface pressure (coefficient ratios of temperature/pressure are 14.33 for Perfusion Area, 11.77 for Peak minus Baseline, and 12.97 for Normalized Peak, respectively). The findings also indicate that post-load metabolic repayment varied with temperature only at higher pressures, suggesting protective vasodilation was able to keep pace with mild compression. If confirmed in subsequent studies, the results suggest that managing both skin pressure and temperature may reduce the risk of ischemia.

RESNA's position on wheelchairs used as seats in motor vehicles.

This position paper is based on the premise that those who ride seated in wheelchairs are entitled to equivalent occupant safety when they are traveling in motor vehicles. The document summarizes research and best practice for safety and selection of crashworthy wheelchairs with the requisite features required by the WC19 safety standard when it is necessary for individuals to use a wheelchair as a seat in a motor vehicle. Recommendations are based on data from accident and injury databases, prior research and a synopsis of the design, testing, performance and labeling requirements of ANSI and ISO voluntary industry standards for wheelchair transportation safety. This paper is intended for an audience of consumers, rehabilitation and health care professionals, manufacturers of wheelchairs and wheelchair transportation equipment and those who make reimbursement and public policy decisions.

User evaluation of three wheelchair securement systems in large accessible transit vehicles.

Ease of use, comfort, security, and independent use of three types of wheelchair securement systems were evaluated in a large accessible transit vehicle by 20 wheelchair and scooter users. The securement systems included a 4-point tie-down system, a prototype autodocking system, and a prototype rear-facing wheelchair passenger (RF-WP) system. Study participants took a 15-minute city ride and completed a survey. Participants responded positively to the autodocking and RF-WP systems that were quicker and easier to use and allowed more independent use than the 4-point tie-down system (p < 0.001). There was concern regarding the RF-WP system that rear-facing travel made it more difficult to see upcoming stops and was less comfortable than a forward-facing ride and that the system may damage wheelchair wheels during use. The majority of participants preferred using an autodocking system because it allowed secure and independent forward-facing travel. Participants found it undesirable, however, that a wheelchair-mounted docking adaptor was needed to use the autodocking system. Study results indicate a need for improved securement systems for forward-facing use that do not require a wheelchair adaptation and can be easily and independently used by wheelchair and scooter users.

Interface shear and pressure characteristics of wheelchair seat cushions.

Pressure ulcer incidence rates have remained constant despite advances in support surface technology. Interface shear stress is recognized as a risk factor for pressure ulcer development and is the focus of many shear reduction technologies incorporated into wheelchair cushions; however, shear reduction has not been quantified in the literature. We evaluated 21 commercial wheelchair seat cushions using a new methodology developed to quantify interface shear stress, interface pressure, and horizontal stiffness. Interface shear stress increased significantly with applied horizontal indenter displacement, while no significant difference was found for interface pressure. Material of construction resulted in significant differences in interface shear stress, interface pressure, and horizontal stiffness. This study shows that the existing International Organization for Standardization (ISO) 16840-2 horizontal stiffness measure provides similar information to the new horizontal stiffness measure. The lack of a relationship between interface shear stress and the overall horizontal stiffness measure, however, suggests that a pressure and shear force sensor should be used with the ISO 16840-2 horizontal stiffness measure to fully quantify a cushion's ability to reduce interface shear stress at the patient's bony prominences.