Our contemporary understanding of the aetiology of pressure ulcers/pressure injuries.

In 2019, the third and updated edition of the Clinical Practice Guideline (CPG) on Prevention and Treatment of Pressure Ulcers/Injuries has been published. In addition to this most up-to-date evidence-based guidance for clinicians, related topics such as pressure ulcers (PUs)/pressure injuries (PIs) aetiology, classification, and future research needs were considered by the teams of experts. To elaborate on these topics, this is the third paper of a series of the CPG articles, which summarises the latest understanding of the aetiology of PUs/PIs with a special focus on the effects of soft tissue deformation. Sustained deformations of soft tissues cause initial cell death and tissue damage that ultimately may result in the formation of PUs/PIs. High tissue deformations result in cell damage on a microscopic level within just a few minutes, although it may take hours of sustained loading for the damage to become clinically visible. Superficial skin damage seems to be primarily caused by excessive shear strain/stress exposures, deeper PUs/PIs predominantly result from high pressures in combination with shear at the surface over bony prominences, or under stiff medical devices. Therefore, primary PU/PI prevention should aim for minimising deformations by either reducing the peak strain/stress values in tissues or decreasing the exposure time.

A comparison of air-cell and gel surgical table pads and an evaluation of the influence of pressure distribution and other factors on pressure injury prevention.

Guidelines for pressure injury prevention consider the use of pressure-redistributing pads to prevent tissue deformation. However, limited research exists to assess the pressure distribution provided by the operating tables and the effectiveness of pressure-redistributing pads in preventing pressure injuries. In this study, we compared the pressure distribution properties of two surgical table pads and identified parameters influencing pressure injury outcomes after a lengthy surgical procedure. Twenty-seven patients undergoing left ventricular assist device implantation surgery participated in the study. Participants were randomly assigned to use either an air cell-based pad or a gel pad. Interface pressure was recorded during the surgery. We analyzed the effect of surgical table pad type, interface pressure distribution and pressure injury outcomes and analyzed what characteristics of the patients and the interface pressure are most influential for the development of pressure injuries. Comparing the interface pressure parameters between the air-cell group and the gel group, only the peak pressure index x time was significantly different (p < 0.05). We used univariate logistic regression analysis to identify significant predictors for the pressure injury outcome. The support surface was not significant. And, among patient characteristics, only age and BMI were significant (p ≤ 0.05). Among the interface pressure parameters, pressure density maxima, peak pressure index x time, and coefficient of variation were significant for pressure injury outcome (p ≤ 0.05). Peak pressure index, average pressure, and the surgery length were not statistically significant for pressure injury outcomes.

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.

Medical Rehabilitation: Guidelines to Advance the Field With High-Impact Clinical Trials.

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.

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.

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.

Inducible protein-10, a potential driver of neurally controlled interleukin-10 and morbidity in human blunt trauma.

OBJECTIVE: Blunt trauma and traumatic spinal cord injury induce systemic inflammation that contributes to morbidity. Dysregulated neural control of systemic inflammation postinjury is likely exaggerated in patients with traumatic spinal cord injury. We used in silico methods to discern dynamic inflammatory networks that could distinguish systemic inflammation in traumatic spinal cord injury from blunt trauma. DESIGN: Retrospective study. SETTINGS: Tertiary care institution. PATIENTS: Twenty-one severely injured thoracocervical traumatic spinal cord injury patients and matched 21 severely injured blunt trauma patients without spinal cord injury. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Serial blood samples were obtained from days 1 to 14 postinjury. Twenty-four plasma inflammatory mediators were quantified. Statistical significance between the two groups was determined by two-way analysis of variance. Dynamic Bayesian network inference was used to suggest dynamic connectivity and central inflammatory mediators. Circulating interleukin-10 was significantly elevated in thoracocervical traumatic spinal cord injury group versus non-spinal cord injury group, whereas interleukin-1ß, soluble interleukin-2 receptor-α, interleukin-4, interleukin-5, interleukin-7, interleukin-13, interleukin-17, macrophage inflammatory protein 1α and 1ß, granulocyte-macrophage colony-stimulating factor, and interferon-γ were significantly reduced in traumatic spinal cord injury group versus non-spinal cord injury group. Dynamic Bayesian network suggested that post-spinal cord injury interleukin-10 is driven by inducible protein-10, whereas monocyte chemotactic protein-1 was central in non-spinal cord injury dynamic networks. In a separate validation cohorts of 356 patients without spinal cord injury and 85 traumatic spinal cord injury patients, individuals with plasma inducible protein-10 levels more than or equal to 730 pg/mL had significantly prolonged hospital and ICU stay and days on mechanical ventilator versus patients with plasma inducible protein-10 level less than 730 pg/mL. CONCLUSION: This is the first study to compare the dynamic systemic inflammatory responses of traumatic spinal cord injury patients versus patients without spinal cord injury, suggesting a key role for inducible protein-10 in driving systemic interleukin-10 and morbidity and highlighting the potential utility of in silico tools to identify key inflammatory drivers.

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.

Measuring interface pressure and temperature in the operating room.

BACKGROUND: 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. OBJECTIVE: The objective of this study was to determine a methodology to measure interface pressure and temperature during long hours of surgery consistently. SAMPLE: Five patients undergoing liver transplants were recruited from the University of Pittsburgh Medical Center. METHODS AND OUTCOMES: 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. RESULTS: Pressure mapping and temperature mapping are appropriate to quantify interface pressure and temperature during surgery. CONCLUSION: 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.

An exploratory study analyzing demographics and opinions of assistive technology professionals within the complex rehab technology industry.

This exploratory study investigated the demographics of Assistive Technology Professionals (ATPs) regarding their age, education, certifications, ethnicity, gender, veteran status, disability status, method of financial compensation, company type, and category. In addition, it analyzed opinions on the Complex Rehab Technology (CRT) industry regarding education level and licensure. An 18-question survey developed and disseminated by the University of Pittsburgh in collaboration with the National Coalition for Assistive & Rehab Technology (NCART) resulted in 252 responses from current ATPs in the Supplier/Manufacturing industry. The average age of respondents of 51.9 years showed to be above the national average workforce age of 42.2 years. Data were analyzed as a whole and by comparing answers for respondents below and above the average age. 92.4% of the respondents were Caucasian and 79.0% were male showing a need for diversity in the field. Forty-five percent of the younger age group had additional certifications compared to 30% of the older group. 79.8% of all respondents would recommend the ATP profession to someone looking for a career. Findings support the need to increase awareness of the ATP supplier/manufacturing profession to attract younger professionals including those from minority groups. Findings also support the need for additional training for the profession.

Telerehabilitation wheeled mobility and seating assessments compared with in person.

OBJECTIVE: To evaluate the equivalency of wheeled mobility and seating assessments delivered under 2 conditions: in person (IP) at a local clinic and via Telerehabilitation at remotely located clinics. DESIGN: The study used a prospective, multicenter controlled nonrandomized design to investigate wheeled mobility and seating assessments. SETTING: Five wheelchair clinics in Western Pennsylvania. PARTICIPANTS: Participants (N=98) in need of new wheeled mobility and seating were recruited and consented for IP assessments at the Center for Assistive Technology (n=50) and Telerehabilitation (n=48) assessments at remotely located clinics. INTERVENTIONS: The telerehabilitation condition used a custom videoconferencing system to connect a wheeled mobility and seating expert at the University of Pittsburgh's Rehabilitation Engineering Research Center on Telerehabilitation to a remote clinic. MAIN OUTCOME MEASURES: Study findings were based on the level of function the participants showed with their new wheeled mobility and seating devices as measured by using the Functioning Everyday with a Wheelchair (FEW) outcome tool. RESULTS: The results revealed no significant differences between the FEW pretest average or item scores for the 2 conditions or the FEW posttest average or item scores except for the FEW transportation item. The average FEW and FEW item scores reached the established clinically relevant pretest-posttest difference of 1.85, and the change scores were significantly different. The difference between FEW means based on posttest confidence intervals indicated that telerehabilitation was equally effective as IP rehabilitation. CONCLUSIONS: An expert practitioner located at least 125 miles away from each of the remote sites used a secured videoconferencing system to consult from a geographic distance on wheeled mobility and seating evaluations via telerehabilitation. Compared with participants receiving standard IP care, the telerehabilitation treatment condition was equally effective on all but 1 outcome.

VISYTER: versatile and integrated system for telerehabilitation.

The versatile and integrated system for telerehabilitation (VISYTER) is a software platform for developing various telerehabilitation applications. VISYTER has been designed to take into account the environments and requirements of rehabilitation services. The requirements considered in the platform design include minimal equipment beyond what is available in many rehabilitation settings, minimal maintenance, and ease of setup and operation. In addition, the platform has been designed to be able to adjust to different bandwidths, ranging from the very fast new generation of Internet to residential broadband connections. VISYTER is a secure integrated system that combines high-quality videoconferencing with access to electronic health records and other key tools in telerehabilitation such as stimuli presentation, remote multiple camera control, remote control of the display screen, and an eye contact teleprompter. The software platform is suitable for supporting low-volume services to homes, yet scalable to support high-volume enterprise-wide telehealth services. The VISYTER system has been used to develop a number of telerehabilitation applications, including a remote wheelchair prescription, adult autistic assessments, and international physical therapy teleconsultations. An evaluation of VISYTER for delivering a remote wheelchair prescription was conducted on 48 participants. Results of the evaluation indicate a high level of satisfaction from patients with the use of VISYTER. The versatility and cost-effectiveness of the platform has the potential for a wide range of telerehabilitation applications and potentially may lower the technical and economic barriers of telemedicine adoption.

Effects of local cooling on sacral skin perfusion response to pressure: implications for pressure ulcer prevention.

People with spinal cord injuries are at high risk for developing pressure ulcers. Increased skin temperature is one of the extrinsic causative factors for this multi-factorial disease. Previous animal studies revealed that local skin cooling reduced the severity of ulceration, and cooling is widely used in plastic surgery and organ transplants for tissue preservation. The objectives of this pilot study were to develop test protocols and instrumentation and to investigate the effect of local cooling on skin perfusion response to pressure on young healthy human subjects. Reactive hyperemia was quantified in this study to compare the effects of pressure with and without cooling. Reactive hyperemia is a normal physiological response occurring after vessel occlusion. Laser Doppler flowmetry was used to measure skin blood flow. Time-dependent spectral analysis was used to analyze and decompose the blood flow data into frequency ranges associated with specific blood flow control mechanisms. The study used a repeated measures design with two test conditions: 8 kPa of pressure with and without cooling to 25 degrees C. We hypothesized that local cooling would reduce the post-ischemic reactive hyperemic response induced by the rigid indenter. Time series results showed that normalized peak perfusion response was significantly lower with cooling (p=0.019). Time-dependent spectral analysis results suggested that both metabolic and myogenic responses contribute to this protective effect. Findings from our study on humans were consistent with previous animal studies. Additional studies on individuals with spinal cord injury are planned to further evaluate the cooling effect in a high-risk population.

Wavelet-based spectrum analysis of sacral skin blood flow response to alternating pressure.

OBJECTIVES: To provide insight into the physiologic mechanisms associated with alternating pressure, using wavelet analysis of skin blood flow (SBF) oscillations, and to determine whether the application of alternating pressure induces myogenic responses, thereby enhancing SBF as compared with constant loading. DESIGN: Repeated-measures design. SETTING: University research laboratory. PARTICIPANTS: Healthy, young adults (N=10; 5 men, 5 women; mean age +/- standard deviation, 30.0+/-3.1 y). INTERVENTION: Alternating pressure for 20 minutes (four 5-min cycles with either 60 mmHg or 3 mmHg) and constant loading for 20 minutes at 30 mmHg on the skin over the sacrum. MAIN OUTCOME MEASURES: A laser Doppler flowmeter was used to measure sacral SBF response to both alternating pressure and constant loading. Wavelet-based spectrum analysis of SBF oscillations was used to assess underlying physiologic mechanisms including endothelium-related metabolic (.008-.02 Hz), neurogenic (.02-.05 Hz), and myogenic (.05-.15 Hz) controls. RESULTS: Alternating pressure stimulated an increase in sacral SBF of compressed soft tissues as compared with constant loading (P<.01). SBF during the high-pressure phase of 4 alternating pressure cycles showed an increasing trend. An increase in power in metabolic frequency range and a decrease in power in the myogenic frequency range during alternating pressure were observed compared with SBF prior to loading. Power increased in the myogenic frequency range during the low-pressure phase of alternating pressure and decreased during the high-pressure phase. CONCLUSIONS: SBF control mechanisms, as assessed by the characteristic frequencies embedded in SBF oscillations, show different responses to 2 loading pressures with the same average pressure but different patterns. Our study suggests that optimization of operating parameters and configurations of alternating pressure support surfaces to compensate for impaired SBF control mechanisms in pathologic populations may be possible using wavelet analysis of blood flow oscillations.

Effectiveness evaluation of a remote accessibility assessment system for wheelchair users using virtualized reality.

OBJECTIVE: To determine the value of the Remote Accessibility Assessment System (RAAS), a 3-dimensional (3D) image reconstruction technology designed to analyze accessibility of the target built environment in a virtualized reality, in assessing a built environment's accessibility by calculating the congruence level between the RAAS and conventional in-person method. DESIGN: Repeated-measures (within-subject) design. SETTING: A university research laboratory. PARTICIPANTS: Three homes for people who use wheeled mobility devices. INTERVENTION: Home physical environment was divided into several potential problem areas such as entrance, hallway, bathroom, and living room. Each area was identified by several tasks that might be performed in it. All possible tasks in each area within each home were evaluated using 2 methods: RAAS and the conventional in-person assessment. The evaluations were performed by a different home modification specialist for each method. MAIN OUTCOME MEASURES: Conventional in-person assessments were cross-tabulated with assessments from RAAS, with which there are 4 possible assessment combinations. A true positive (checked-checked) occurs when the RAAS method checks the target task as problematic and it is also checked as problematic by the conventional in-person method. True negative (not checked-not checked), false positive (not checked-checked), and false negative (checked-not checked) were also identified as the same way. RESULTS: The proportion of overall agreement was high at 94.1% and the overall sensitivity and specificity was 95.6% and 90.3%, respectively. A significant kappa coefficient of .857 and the 95% confidence interval of the odds ratio of 104.062 to 404.921 were calculated and a high level of overall agreement rate was shown. A high P value (.868) of the McNemar test implied that there was no marginal homogeneity, that is, no tendency to identify the task incorrectly in the positive or negative direction. CONCLUSIONS: This system proved that virtualized reality and 3D reconstruction technology may provide an effective means to investigate the architectural features of a built environment without an expert visiting the site. This system could become an efficient tool for the service provider and can provide expert service to underserved clients that would otherwise be unavailable.

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.

Are all pressure ulcers the result of deep tissue injury? A review of the literature.

Pressure ulcers are a common problem that significantly contributes to morbidity and mortality. To elucidate the confusion surrounding the origin of pressure ulcers, the question of whether pressure ulcers are caused exclusively by deep tissue injury is addressed. A review of the literature relevant to the pathophysiology and pathogenesis of pressure ulcers is presented and focuses on studies that examine the relationship between mechanical stresses and deep and superficial tissue injury. The studies suggest that deep tissue is more susceptible than superficial tissue to injury caused by externally applied pressure; clinically superficial skin injuries induced by pressure tend to be associated with deep tissue damage; and superficial injuries appear to be caused by factors other than pressure. Based on these observations, pressure ulcers are believed to be the result of deep tissue damage, implying that prevention and treatment of superficial lesions need not necessarily conform to pressure ulcer management that makes eliminating pressure the highest priority. Conversely, the treatment of pressure ulcers should account for the likelihood, even if not visually noted, that deep tissue is involved.