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... more
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 pre- and post-aging are presented and changes in test outcome metrics due to aging were 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.
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The purpose of this project was to design and develop a novel wheelchair with a unique combination of features. This wheelchair design was intended to address a market need for a wheelchair capable of folding compactly for stowage (e.g.,... more
The purpose of this project was to design and develop a novel wheelchair with a unique combination of features. This wheelchair design was intended to address a market need for a wheelchair capable of folding compactly for stowage (e.g., overhead compartments during commercial air travel), accessing narrow passageways and other areas requiring a compact profile and footprint, and providing a high degree of maneuverability. Our intent was to design an “Enhanced Access Wheelchair” to achieve these capabilities without sacrificing the performance characteristics essential for everyday use (Figure 24). We also attempted to determine the feasibility of incorporating fiber reinforced material technology. TASK: MM-1 STRUCTURAL IMPROVEMENTS TO MANUAL WHEELCHAIRS
Abstract Ultrasound and magnetic resonance imaging (MRI) are well-established medical imaging technologies. Researchers have had much success using these technologies to improve our understanding of pressure injury etiology, but their use... more
Abstract Ultrasound and magnetic resonance imaging (MRI) are well-established medical imaging technologies. Researchers have had much success using these technologies to improve our understanding of pressure injury etiology, but their use in clinical practice for pressure injury risk assessment and monitoring has not been established. The process for interpreting the images is a critical step toward clinical implementation, and much of the recent work described in this chapter is aimed at developing these processes. This chapter is a review of the progress made toward using ultrasound and MRI technologies to achieve a better understanding of pressure injury risk factors and toward the clinical use of these technologies to assess wounds at an early stage in their development. Other work reviewed describes the advancement toward clinical implementation of these technologies to track wound progression.
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ABSTRACT COVID‐19 has infected millions of patients and impacted healthcare workers worldwide. Personal Protective Equipment (PPE) is a key component of protecting frontline clinicians against infection. The benefits of PPE far outweigh... more
ABSTRACT COVID‐19 has infected millions of patients and impacted healthcare workers worldwide. Personal Protective Equipment (PPE) is a key component of protecting frontline clinicians against infection. The benefits of PPE far outweigh the risks, nonetheless, many clinicians are exhibiting skin injury caused by PPE worn incorrectly. These skin injuries, ranging from lesions to open wounds are concerning because they increase the susceptibility of viral infection and transmission to other individuals. Early into the COVID‐19 pandemic (April 2020), the U.S. National Pressure Injury Advisory Panel (NPIAP) developed a series of position statements to improve wear‐ability of PPE and protect healthcare professionals and their patients as safe from harm as possible under the circumstances. The NPIAP positions, which were formed by conducting a systematic review of what was known at the time, include: (1) Prepare skin before and after wearing PPE with skin sealants, barrier creams and moisturizers; (2) Frequent PPE offloading to relieve pressure and shear applied to skin; (3) treat visible skin injuries immediately caused by PPE to minimize future infection; (4) non‐porous dressings may provide additional skin protection, but lack evidence; (5) health systems should take care to educate clinicians about placement and personal hygiene related to handling PPE. Throughout all of these practices, handwashing remains a top priority to handle PPE. These NPIAP positions provided early guidance to reduce the risk of skin injury caused by PPE based on available research regarding PPE injuries, a cautious application of evidence‐based recommendations on prevention of device related pressure injuries in patients and the expert opinion of the NPIAP Board of Directors. Clinicians who adhere to these recommendations reduce the prospects of skin damage and long‐term effects (e.g. scarring). These simple steps to minimize the risk of skin injury and reduce the risk of coronavirus infection from PPE can help.
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The α7 neuronal nicotinic acetylcholine receptors (α7nAChRs) are essential for anti-inflammatory responses. The human-specific CHRFAM7A gene and its 2bp deletion polymorphism (Δ2bp variant) encodes a structurally-deficient α7nAChRs that... more
The α7 neuronal nicotinic acetylcholine receptors (α7nAChRs) are essential for anti-inflammatory responses. The human-specific CHRFAM7A gene and its 2bp deletion polymorphism (Δ2bp variant) encodes a structurally-deficient α7nAChRs that may impact the anti-inflammatory function. We studied 45 spinal cord injury (SCI) patients for up to six weeks post SCI to investigate the role of the Δ2bp variant on multiple circulating inflammatory mediators and two outcome measures (neuropathic pain and risk of pressure ulcers). The patient’s SCI were classified as either severe or mild. Missing values were imputed. Overall genetic effect was conducted with independent sample t-test and corrected with false discovery rate (FDR). Univariate analysis and regression analysis were applied to evaluate the Δ2bp effects on temporal variation of inflammatory mediators post SCI and their interaction with outcome measures. In severe SCI, the Δ2bp carriers showed higher levels of circulating inflammatory me...
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Abstract Ultrasound and magnetic resonance imaging (MRI) are well-established medical imaging technologies. Researchers have had much success using these technologies to improve our understanding of pressure injury etiology, but their use... more
Abstract Ultrasound and magnetic resonance imaging (MRI) are well-established medical imaging technologies. Researchers have had much success using these technologies to improve our understanding of pressure injury etiology, but their use in clinical practice for pressure injury risk assessment and monitoring has not been established. The process for interpreting the images is a critical step toward clinical implementation, and much of the recent work described in this chapter is aimed at developing these processes. This chapter is a review of the progress made toward using ultrasound and MRI technologies to achieve a better understanding of pressure injury risk factors and toward the clinical use of these technologies to assess wounds at an early stage in their development. Other work reviewed describes the advancement toward clinical implementation of these technologies to track wound progression.
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ABSTRACT COVID‐19 has infected millions of patients and impacted healthcare workers worldwide. Personal Protective Equipment (PPE) is a key component of protecting frontline clinicians against infection. The benefits of PPE far outweigh... more
ABSTRACT COVID‐19 has infected millions of patients and impacted healthcare workers worldwide. Personal Protective Equipment (PPE) is a key component of protecting frontline clinicians against infection. The benefits of PPE far outweigh the risks, nonetheless, many clinicians are exhibiting skin injury caused by PPE worn incorrectly. These skin injuries, ranging from lesions to open wounds are concerning because they increase the susceptibility of viral infection and transmission to other individuals. Early into the COVID‐19 pandemic (April 2020), the U.S. National Pressure Injury Advisory Panel (NPIAP) developed a series of position statements to improve wear‐ability of PPE and protect healthcare professionals and their patients as safe from harm as possible under the circumstances. The NPIAP positions, which were formed by conducting a systematic review of what was known at the time, include: (1) Prepare skin before and after wearing PPE with skin sealants, barrier creams and moisturizers; (2) Frequent PPE offloading to relieve pressure and shear applied to skin; (3) treat visible skin injuries immediately caused by PPE to minimize future infection; (4) non‐porous dressings may provide additional skin protection, but lack evidence; (5) health systems should take care to educate clinicians about placement and personal hygiene related to handling PPE. Throughout all of these practices, handwashing remains a top priority to handle PPE. These NPIAP positions provided early guidance to reduce the risk of skin injury caused by PPE based on available research regarding PPE injuries, a cautious application of evidence‐based recommendations on prevention of device related pressure injuries in patients and the expert opinion of the NPIAP Board of Directors. Clinicians who adhere to these recommendations reduce the prospects of skin damage and long‐term effects (e.g. scarring). These simple steps to minimize the risk of skin injury and reduce the risk of coronavirus infection from PPE can help.
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Assessing the accessibility using 3D Virtual Reality and telecommunication technology has influenced home adaptation to improve accessibility in homes for individuals with disabilities, especially with Spinal Cord Injury. To provide... more
Assessing the accessibility using 3D Virtual Reality and telecommunication technology has influenced home adaptation to improve accessibility in homes for individuals with disabilities, especially with Spinal Cord Injury. To provide clients with quantitative ideas on home adaptation with levels of accessibility, we propose a tentative method of measuring accessibility in home. There are a number of assessment protocols to assist
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To systematically collect information on active research grants to characterize pressure ulcer research funding in the United States and to identify potential targets for future research and funding initiatives. DESIGN A descriptive... more
To systematically collect information on active research grants to characterize pressure ulcer research funding in the United States and to identify potential targets for future research and funding initiatives. DESIGN A descriptive study. The investigators identified 32 grants, representing 16,444,117 US dollars in research funding. The majority of this funding came from federal sources, including the National Institutes of Health (90%), the Department of Veterans Affairs (7%), the National Institute on Disability and Rehabilitation Research (2%), and the Agency for Healthcare Research and Quality (1%). One quarter of pressure ulcer research grants related to quality improvement. Additional topic areas included risk factors or risk assessment tools (19%), adjunctive therapy (16%), mobilization (13%), and pressure management in foot care for patients with diabetes mellitus (9%). Further grants were in the areas of incidence, assessing tissue damage or healing, support surfaces, dressings and topical agents, nutrition, economic evaluation, and pain. The investment in pressure ulcer research is minute compared with pressure ulcer treatment expenditures. Policy makers are urged to encourage increased federal and foundation funding for research concerning pressure ulcers. Researchers are also encouraged to develop well-designed proposals to obtain available research funding. Additional research is needed in the areas of pressure ulcer incidence and prevalence, support surface design and use, pain, operative treatment, economic impact, and education strategies for caregivers and patients.
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Research Interests: Nursing, Nonlinear dynamics, Medicine, Linear models, Elasticity, and 15 moreHumans, Ultrasonography, Female, Male, Fibrosis, Clinical Sciences, Aged, Middle Aged, Adult, Leg, Predictive value of tests, Case Control Studies, Biomechanical Phenomena, Severity of Illness Index, and Mechanical Property
The purpose of this project was to design and develop a novel wheelchair with a unique combination of features. This wheelchair design was intended to address a market need for a wheelchair capable of folding compactly for stowage (e.g.,... more
The purpose of this project was to design and develop a novel wheelchair with a unique combination of features. This wheelchair design was intended to address a market need for a wheelchair capable of folding compactly for stowage (e.g., overhead compartments during commercial air travel), accessing narrow passageways and other areas requiring a compact profile and footprint, and providing a high degree of maneuverability. Our intent was to design an “Enhanced Access Wheelchair” to achieve these capabilities without sacrificing the performance characteristics essential for everyday use (Figure 24). We also attempted to determine the feasibility of incorporating fiber reinforced material technology. TASK: MM-1 STRUCTURAL IMPROVEMENTS TO MANUAL WHEELCHAIRS
Research Interests:
Research Interests: Nursing, Nonlinear dynamics, Medicine, Linear models, Elasticity, and 15 moreHumans, Ultrasonography, Female, Male, Fibrosis, Clinical Sciences, Aged, Middle Aged, Adult, Leg, Predictive value of tests, Case Control Studies, Biomechanical Phenomena, Severity of Illness Index, and Mechanical Property
To determine if the use of pressure-reducing wheelchair cushions for elderly nursing home resident wheelchair users who are at high risk for developing sitting-acquired pressure ulcers would result in a lower incidence rate of pressure... more
To determine if the use of pressure-reducing wheelchair cushions for elderly nursing home resident wheelchair users who are at high risk for developing sitting-acquired pressure ulcers would result in a lower incidence rate of pressure ulcers, a greater number of days until ulceration, and lower peak interface pressures compared with the use of convoluted foam cushions over a 12-month period. To determine the feasibility of conducting a subsequent full-scale definitive trial to evaluate the use of pressure-reducing seat cushions for elderly nursing home resident wheelchair users. Randomized control trial 2200-bed skilled nursing facilities (1 suburban and 1 urban academic medical center) 32 male and female at-risk nursing home residents who were wheelchair users > or = 65 years of age. Participants had Braden Scale scores < or = 18, Braden Activity and Mobilitysubscale scores < or = 5, no sitting surface pressure ulcers, and a daily wheelchair sitting tolerance of more than 6 hours. All met criteria for using the ETAC Twin wheelchair. Seating evaluation with pressure-mapping and subsequent seating prescription. Subjects were assigned to either a foam (n=17) or pressure-reducing cushion (n=15) group and weekly assessments of skin and pressure ulcer risk were made. Incidence of pressure ulcers, days to ulceration, and peak interface pressure. At a 95% confidence interval, a 2-tailed analysis showed no differences between the FOAM and pressure-reducing cushion groups for pressure ulcer incidence, total days to pressure ulcer, or initial peak interface pressure. Pressure-reducing cushions were more effective in preventing sitting-acquired (ischial) pressure ulcers (P<.005). Higher interface pressures were associated with a higher incidence of pressure ulcers (P<.001). A definitive randomized control multicenter cushion trial is feasible with a sample size of 50 to 100 per study group. In the definitive trial, the definition of sitting-acquired pressure ulcers should be limited to lesions occurring over the ischial tuberosities.
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To determine if the use of pressure-reducing wheelchair cushions for elderly nursing home resident wheelchair users who are at high risk for developing sitting-acquired pressure ulcers would result in a lower incidence rate of pressure... more
To determine if the use of pressure-reducing wheelchair cushions for elderly nursing home resident wheelchair users who are at high risk for developing sitting-acquired pressure ulcers would result in a lower incidence rate of pressure ulcers, a greater number of days until ulceration, and lower peak interface pressures compared with the use of convoluted foam cushions over a 12-month period. To determine the feasibility of conducting a subsequent full-scale definitive trial to evaluate the use of pressure-reducing seat cushions for elderly nursing home resident wheelchair users. Randomized control trial 2200-bed skilled nursing facilities (1 suburban and 1 urban academic medical center) 32 male and female at-risk nursing home residents who were wheelchair users > or = 65 years of age. Participants had Braden Scale scores < or = 18, Braden Activity and Mobilitysubscale scores < or = 5, no sitting surface pressure ulcers, and a daily wheelchair sitting tolerance of more than 6 hours. All met criteria for using the ETAC Twin wheelchair. Seating evaluation with pressure-mapping and subsequent seating prescription. Subjects were assigned to either a foam (n=17) or pressure-reducing cushion (n=15) group and weekly assessments of skin and pressure ulcer risk were made. Incidence of pressure ulcers, days to ulceration, and peak interface pressure. At a 95% confidence interval, a 2-tailed analysis showed no differences between the FOAM and pressure-reducing cushion groups for pressure ulcer incidence, total days to pressure ulcer, or initial peak interface pressure. Pressure-reducing cushions were more effective in preventing sitting-acquired (ischial) pressure ulcers (P<.005). Higher interface pressures were associated with a higher incidence of pressure ulcers (P<.001). A definitive randomized control multicenter cushion trial is feasible with a sample size of 50 to 100 per study group. In the definitive trial, the definition of sitting-acquired pressure ulcers should be limited to lesions occurring over the ischial tuberosities.
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There is a high incidence of pressure ulcers (PrUs) during long hours of surgery. Interface pressure and temperature are considered risk factors for PrU development. The objective of this study was to determine a methodology to measure... more
There is a high incidence of pressure ulcers (PrUs) during long hours of surgery. Interface pressure and temperature are considered risk factors for PrU development. The objective of this study was to determine a methodology to measure interface pressure and temperature during long hours of surgery consistently. Five patients undergoing liver transplants were recruited from the University of Pittsburgh Medical Center. Interface pressure and temperature were measured with pressure mapping and temperature mapping for the duration of the surgery. After the surgery, an 8-hour skin check over 48 hours was performed. Pressure mapping and temperature mapping are appropriate to quantify interface pressure and temperature during surgery. This study shows that measuring interface pressure and temperature using pressure and temperature mats is feasible. Further studies are necessary in order to validate the methodology in other types of surgery.
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The purpose of this Special Communication is to summarize guidelines and recommendations stemming from an expert panel convened by the National Institutes of Health, National Center for Medical Rehabilitation Research (NCMRR) for a... more
The purpose of this Special Communication is to summarize guidelines and recommendations stemming from an expert panel convened by the National Institutes of Health, National Center for Medical Rehabilitation Research (NCMRR) for a workshop entitled The Future of Medical Rehabilitation Clinical Trials, held September 29-30, 2016, at the NCMRR offices in Bethesda, Maryland. The ultimate goal of both the workshop and this summary is to offer guidance on clinical trials design and operations to the medical rehabilitation research community, with the intent of maximizing the effect of future trials.
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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... more
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 unbias...
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To identify the inflammatory mediators around the time of pneumonia onset associated with concurrent or later onset of pressure ulcers. Retrospective SETTING: Acute hospitalization and inpatient rehabilitation unit of a university medical... more
To identify the inflammatory mediators around the time of pneumonia onset associated with concurrent or later onset of pressure ulcers. Retrospective SETTING: Acute hospitalization and inpatient rehabilitation unit of a university medical center. NA. Eighty-six individuals with traumatic SCI were included in the initial analyses. Fifteen of the 86 developed pneumonia and had inflammatory mediator data available. Of these 15, seven developed pressure ulcers and eight did not develop pressure ulcers. Twenty-three inflammatory mediators in plasma and urine were assayed using Luminex. The differences in concentrations of plasma and urine inflammatory mediators between the closest time point before and after the diagnosis of pneumonia were calculated. Initial Chi-Square analysis revealed a significant (p=0.02) association between pneumonia and pressure ulcers. Individuals with SCI diagnosed with pneumonia had nearly double the risk for developing pressure ulcers compared to those with no pneumonia. In individuals with pneumonia, Mann Whitney U exact tests suggested an association (p<0.05) between the formation of a first pressure ulcer and a slight increase in plasma concentrations of tumor necrosis factor-alpha (TNF-α), and decrease in urine concentrations of TNF-α, and granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin (IL)-15 following onset of pneumonia. 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 pressure ulcers in individuals with pneumonia post traumatic SCI.
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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... more
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). Retrospective. 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. 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. 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.
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Regardless of the field, agenda-setting processes are integral to establishing research and development priorities. Beginning in 1998, the National Institute on Disability and Rehabilitation Research mandated that each newly funded... more
Regardless of the field, agenda-setting processes are integral to establishing research and development priorities. Beginning in 1998, the National Institute on Disability and Rehabilitation Research mandated that each newly funded Rehabilitation Engineering and Research Center (RERC) hold a state-of-the-science consensus forum during the third year of its 5-year funding cycle. NIDRR's aim in formalizing this agenda-setting process was to facilitate the formulation of future research and development priorities for each respective RERC. In February 2001, the RERC on Wheeled Mobility, University of Pittsburgh, conducted one of the first such forums. The scope encompassed both current scientific knowledge and clinical issues. In preparation, expert interviews were carried out to establish the focus for the forum. Because a stakeholder forum on wheelchair technology had recently been held, opinion favored wheelchair seating as the focus and included the following core areas: seating for use in wheelchair transportation, seated postural control, seating discomfort, and tissue integrity management. The aim of this report is to present a summary of the workshop outcomes, describe the process, and increase awareness of this agenda-setting process in order to enhance future participation in a process that critically influences the field of wheeled mobility.
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A focus group comprised of persons who use power wheelchairs and professionals working in the field were asked to participate in a brainstorming session to determine priorities for the development and application of power mobility input... more
A focus group comprised of persons who use power wheelchairs and professionals working in the field were asked to participate in a brainstorming session to determine priorities for the development and application of power mobility input devices and control concepts. The group consensus was that durability and reliability are the most important criteria. Essentially, the expectation is that a power wheelchair must work everyday in the way a person needs it and wants it. At the same time, there is a desire to enhance and advance the features of input devices and control systems. Many would say these changes constitute designing "smarter" power wheelchairs, such as systems that can independently detect obstacles and can provide users with more feedback. This paper presents the rationale behind forming this focus group and details of the results of a brainstorming session where ideas were generated and prioritized. The five most important issues as determined by the group are discussed in depth.
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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. Retrospective, secondary analyses of data obtained from... more
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. 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. Not applicable. 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 Ame...
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... more
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.
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Research Interests: Assistive Technology, IP, Activities of Daily Living, Mobility, Prospective studies, and 15 moreHumans, Videoconferencing, Female, Male, Orthopedics, CAT, Wheelchairs, Clinical Sciences, Middle Aged, Public health systems and services research, Wheel, Chi Square Distribution, Mobility limitation, Disability Evaluation, and Engineering Research Center
Research Interests: Research Design, Multiple sclerosis, Imaging, Cerebral Palsy, Probability, and 15 moreMobility, Paraplegia, Humans, Image Reconstruction, Female, Male, Confidence intervals, Clinical Sciences, Sensitivity and Specificity, Congruence, Remote Access, Environment, Disabled Person, Disabled Persons, and False Positive
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The design of a system to facilitate investigations of the loading of the human body on a seat surface and the ongoing evaluation of a prototype system are presented. Knowledge and understanding of the effect of support surface shape on... more
The design of a system to facilitate investigations of the loading of the human body on a seat surface and the ongoing evaluation of a prototype system are presented. Knowledge and understanding of the effect of support surface shape on load distribution at the body and seat interface are vital components of an automated seat contour design and fabrication system.
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ABSTRACT Many powered wheelchair users have difficulty manoeuvring in confined spaces. Common tasks such as traversing through doorways, turning around in halls or travelling on a straight path are complicated by an inability to... more
ABSTRACT Many powered wheelchair users have difficulty manoeuvring in confined spaces. Common tasks such as traversing through doorways, turning around in halls or travelling on a straight path are complicated by an inability to accurately and reliably control the wheelchair with a joystick or other common input device, or by a sensory impairment that prevents the user from receiving feedback from the environment. An active joystick with force feedback to indicate obstacles in the environment has been developed. Two force feedback schemes designed to assist a powered wheelchair user have been developed and implemented using the active joystick. The development of the joystick and associated control algorithms are described.