Using high-resolution imaging to study the impact of the Kalogon wheelchair cushion on blood flow in the gluteal area.

AIM OF THE STUDY: This study investigated how the air-bladder offloading mode of the Orbiter by Kalogon wheelchair cushion (Orbiter) affected blood flow in the gluteal region of non-disabled subjects. The hypothesis was that the cushion's offloading mode would improve blood flow, resulting in reduced reactive hyperemia when compared to the static setting, or Loaded Control (LC). Furthermore, the study proposed a technique using a high-resolution image laser speckle contrast system to measure blood flow in the gluteal area. METHODS: Two procedures were carried out, one with the participant sitting on a cushion in LC, and the second, the cushion was set to offloading mode. Blood flow was measured through data imaging after each procedure. Three trials were performed, starting and ending in different cushion bladders. Customized algorithms were used to select regions of interest on the images for calculations. The Wilcoxon Signed-Rank Test was conducted to compare the offloads and loaded control values of each region of interest. Results were considered significant at α = 0.05. RESULTS: Ten healthy, non-disabled adults participated in the study, seven females and three males. There were no significant differences among the participants. However, results showed that seven subjects tended to decrease reactive hyperemia in the offload sequence of trial when the last two bladders offloaded were the sacrum followed by the right ischial tuberosity. CONCLUSIONS: The high-resolution imager showed that the Orbiter Offloads helped reduce reactive hyperemia in seven subjects, potentially improving blood flow. More research is necessary to comprehend the mechanisms of these effects fully.

Use of a Shear Reduction Surface for Prehospital Transport: A Randomized Crossover Study.

OBJECTIVE: To compare the effectiveness of an antishear mattress overlay (ASMO) with a standard ambulance stretcher surface in reducing pressure and shear and increasing patient comfort. METHODS: In this randomized, crossover design, adults in three body mass index categories served as their own controls. Pressure/shear sensors were applied to the sacrum, ischial tuberosity, and heel. The stretcher was placed in sequential 0°, 15°, and 30° head-of-bed elevations with and without an ASMO. The ambulance traveled a closed course, achieving 30 mph, with five stops at each head-of-bed elevation. Participants rated discomfort after each series of five runs. RESULTS: Thirty individuals participated. Each participant had 30 runs (15 with an ASMO, 15 without), for a total of 900 trial runs. The peak-to-peak shear difference between support surfaces was -0.03 N, indicating that after adjustment for elevation, sensor location, and body mass index, peak shear levels at baseline (starting pause) were 0.03 N lower for the ASMO than for the standard surface ( P = .02). The peak-to-peak pressure difference between surfaces was -0.16 mm Hg, indicating that prerun peak-to-peak pressure was 0.16 mm Hg lower with the ASMO versus standard surface ( P = .002). The heel received the most pressure and shear. Discomfort score distributions differed between surfaces at 0° ( P = .004) and 30° ( P = .01); the overall score across all elevations was significantly higher with the standard surface than with the ASMO ( P = .046). CONCLUSIONS: The ASMO reduced shear, pressure, and discomfort. During transport, the ambulance team should provide additional heel offloading.

The Role of Shear Stress and Shear Strain in Pressure Injury Development.

ABSTRACT: Although other patient safety indicators have seen a decline, pressure injury (PI) incidence has continued to rise. In this article, the authors discuss the role of shear stress and shear strain in PI development and describe how accurate assessment and management can reduce PI risk. They provide explanations of shear stress, shear strain, friction, and tissue deformation to support a better clinical understanding of how damaging these forces are for soft tissue. Clinicians must carefully assess each patient's risk factors regarding shear forces within the contexts of activity and mobility. The authors also provide a toolbox of mitigation strategies, including support surface selection, selection of materials that contact the individual, management of immobility using positioning techniques, and the use of safe patient handling techniques. With a clear understanding of how shear forces affect PI risk and mitigation strategies, clinicians will more accurately assess PI risk and improve PI prevention care plans, ultimately reducing PI incidence to become more aligned with other patient safety indicators.

Healthcare-Associated Infections and the Hospital Bed.

OBJECTIVE: Bedframes are a potential source of bacterial contamination, fomites, and healthcare-associated infections for patients with active skin wounds and other underlying conditions. Bedframes also differ in their design, materials, texture, and ease of disassembly for cleaning. In this study, the authors evaluated five hospital bedframes in terms of retained soil and ease of cleaning as rated by volunteers. METHODS: Hospital mattresses were placed on five different bedframes and soiled with mock bodily fluids containing Geobacillus stearothermophilus endospores as an indicator organism for contamination. In a second set of experiments, volunteers evaluated the bedframes for ease of cleaning; fewer than 30% of the volunteers had experience cleaning in hospitals or had previously received infection-control training. Questionnaires evaluated subjective measures such as ease of cleaning and texture. RESULTS: Researchers observed a strong correlation between the initial amount of soil retained, the most probable number calculations of endospore counts, and the number of washes to reach extinction (no detectable endospores). Although volunteers' rankings for ease of cleaning were independent of the amount of soil retained, their rankings correlated with the actual washes to reach undetectable limits and bedframe materials that were perceived as harder to clean. CONCLUSIONS: This study demonstrates the importance of both bedframe design and user cleaning experience in reducing bedframes as a source of healthcare-associated infections.

Comparing the Energy-Stretch Properties of Two Compression Bandage Systems in a Laboratory-Based Test under Controlled Conditions.

OBJECTIVE: To compare the characteristics of two commercially available compression systems, a dual-compression bandage system (DCS) and a traditional two-layer bandage (TLB), using a laboratory bench test. METHODS: The compression systems were evaluated in a computer-controlled tensile test to generate force-deflection curves for each sample. The compressive work and the theoretical pressure applied to the limb by the respective compression bandages were calculated at the maximum stretch and a stretch instructed by the manufacturers. The manufacturer of the DCS provides reference points on how much the bandage should be stretched to provide the desired pressure, and the TLB stretch was calculated from the product's datasheet. RESULTS: The combined results of layers 1 and 2 for the DCS showed greater load and work than the TLB at both the maximum and recommended stretch. The recommended stretch for DCS and TLB was less than 50% of the deflection up to the breaking point. CONCLUSIONS: The high work provided by the two layers of the DCS suggests a wider range of performance than the TLB when applied to the lower limb, especially after the limb volume is initially reduced by compression. Moreover, using the tensile test and the guide of the reference points on layers 1 and 2 from DCS, the calculated pressure achieved the expected values stated by the manufacturer. Human studies should be conducted to determine whether the reference points provided by DCS are beneficial for obtaining repeatable values.

The sorptivity and durability of gelling fibre dressings tested in a simulated sacral pressure ulcer system.

Wound-dressing performances are affected by exudate viscosity, resistance to flow because of gravity, and bodyweight loads, the level of which is related to the body position. Here, we focussed on two dressing properties: (a) Sorptivity-the ability of dressings to transfer exudate away from the wound bed by capillary action-and (b) Durability-the capacity of dressings to maintain their integrity over time and during their removal. Both properties are critically important for avoiding further tissue damage but require the development of new laboratory tests for their measurement. A computer-controlled phantom of an exuding sacral pressure ulcer has therefore been developed and used to compare the performances of Exufiber (Mölnlycke Health Care) vs an alternative market-leading dressing. Sorptivity was determined using weight tests, and durability was measured through tensile tests of the used dressings. For a supine configuration, the Exufiber dressing demonstrated ~three times higher sorptivity and better durability, withstanding ~five times greater strain energy than the other product before failure occurred. This work paves the way for quantitative, standardised testing of dressings in all aspects of exudate management. The reported tests are further suitable for testing dressing combinations or how dressings interact with negative pressure wound therapy.

Keeping Patients Under the Damage Threshold for Pressure Injury: Addressing Microclimate Through Allostasis.

BACKGROUND: Pressure injuries (PI) are an ongoing problem in health care. Current interventions, both from clinicians and support surface technologies, do not sufficiently address PI prevention. PROBLEM: Patient microclimate is a contributing risk factor for PI, one which can be more adequately addressed. However, the acceptable range for microclimate is unknown, in part because the body adapts to changing conditions. APPROACH: Two key concepts in allostasis are finite resources and responding to intrinsic and extrinsic demands. These concepts have not previously been applied to PI treatment or interventions. Addressing microclimate, when coupled with an increasing awareness of the cumulative effect of individual patient risk factors, can help resolve the risk of PI by lowering the cumulative inputs to keep patients under the threshold for tissue damage. CONCLUSION: This new approach, which places microclimate risk into the broader conceptual framework of allostasis, can produce more effective products and interventions to prevent PI.

Use of a Support Surface Standard to Test the Effects of a Turning and Positioning Device Versus Low-Air-Loss Therapy on Temperature and Humidity.

BACKGROUND: Turning and repositioning devices (TRDs) help to reduce strain on caregivers, but clinicians question their effects on humidity and temperature (microclimate) at the skin surface that may increase risk of pressure ulcers. OBJECTIVE: To pilot the use of a standard test for support surfaces to compare microclimate at the skin surface in three scenarios: (1) on a low-air-loss (LAL) surface, (2) on a representative TRD with a basic underpad (TRDU) placed on a LAL surface, and (3) on a negative control with full occlusion. The results are designed to inform clinical decision-making in using a TRD on a LAL surface and the viability of using this test to study TRDs. DESIGN: Measuring humidity and temperature at the device-surface interface using a heated moisture-exuding bronze thermodynamic human model in a laboratory setting. MAIN OUTCOME MEASURE: Humidity and temperature levels across 3 hours 15 minutes of continuous loading with a 45-second complete unloading to simulate a position change at 3 hours. MAIN RESULTS: Relative humidity on the TRDU was below that on the LAL surface for the first 110 minutes and was markedly lower than the negative control for the remainder of humidity testing. Temperature on the TRDU was well below the negative control and negligibly higher than the surface alone throughout testing. The position change enhanced the effects of the TRDU. CONCLUSIONS: The support surface standard test appears useful in evaluating TRDs. This TRD along with the basic underpad is more comparable to a LAL surface than to full occlusion in managing the microclimate of the skin and pressure ulcer risk.

Results of Laboratory Testing for Immersion, Envelopment, and Horizontal Stiffness on Turn and Position Devices to Manage Pressure Injury.

BACKGROUND: A continuing complication, pressure injuries are due to sustained mechanical loading and tissue deformations, which can then be exacerbated by additional intrinsic and extrinsic risk factors. Although support surfaces are designed to mitigate risk factors for pressure injuries, the presence of a turn and position device (TPD) between the patient and support surface may interfere with how support surfaces affect these risk factors. OBJECTIVE: Report the use of the NPIAP's S3I standard test methods to characterize the performance of a support surface when used in conjunction with three different TPDs. DESIGN: Laboratory testing compared three TPDs for Immersion, Envelopment, and Horizontal Stiffness in each of five surface combinations. MAIN OUTCOME MEASURE: Immersion test measures how far mannequin indenter immerses into surface. Envelopment test measures immersion and pressure distribution with hemispherical-indenter with mounted sensor rings. Horizontal Stiffness test measures the shear modulus of the support surface with epicondyle indenter. MAIN RESULTS: For the specific TPDs tested here, the one with an adjustable integrated air bladder improved rather than compromised both the envelopment and the immersion of the support surface alone. Additionally, this TPD provided potential protection against sliding and the associated frictional shear forces. CONCLUSIONS: This paper describes how TPDs should perform in order to help establish which features are needed in a new medical device of this type. Laboratory testing demonstrates it is possible to improve performance of a support surface by applying a TPD as an add-on, thus relieving tissue deformation exposure through more effective pressure redistribution.

Time of Onset to Changes in Skin Condition During Exposure to Synthetic Urine: A Prospective Study.

PURPOSE: The purpose of this study was to evaluate the impact of incontinence on epithelial-moisture barrier function and the subsequent risk for incontinence-associated dermatitis by exposing healthy volunteers to a premium incontinence pad wet with synthetic urine. DESIGN: Prospective, single-group study. PARTICIPANTS AND SETTING: Thirty women 65 years or older participated in the study. Participants had healthy skin of the buttocks, perineal, and perigenital areas and were not incontinent of urine or stool. The study was conducted at a contracted clinical research facility in Southeastern United States. METHODS: Four hundred milliliters of synthetic urine was distributed across the width of a premium incontinence pad with wicking technology containing a superabsorbent polymer core. Participants laid supine for a total of 4 hours, with the wet pad under the buttocks. Skin assessments were conducted at baseline prior to contact with the wet pad, at 15 minutes, 30 minutes, and 1, 2, and 4 hours after exposure to the synthetic urine. Outcome measures were skin moisture content, cutaneous pH, transepidermal water loss (TEWL), mean coefficient of friction values (static and dynamic), and tolerability evaluations (expert clinical grader-assessed erythema and participant-assessed discomfort). RESULTS: Mean moisture content of the skin increased from 46.19 ± 22.1 to 1845.28 ± 542.7 micro-Siemens (µS) after just 15 minutes of exposure and was significantly increased at all time points compared to baseline (P < .001). Cutaneous pH increased from 5.67 ± 0.5 to 6.25 ± 0.1 after 15 minutes; pH was higher at all time points compared to baseline (P < .001). Passive transfer of water through the stratum corneum (TEWL) showed an increase from 9.02 ± 2.2 g/m/h at baseline to 16.83 ± 5.2 g/m/h at 4 hours (P < .001). There was a significant increase from baseline to 4 hours in mean coefficient of static friction (0.32 ± 0.01 vs 0.47 ± 0.03; P < .00001) as well as mean coefficient of dynamic friction (0.29 ± 0.01 vs 0.42 ± 0.02; P < .00001). There was a significant increase in erythema and an increase in participant-assessed discomfort at all time points (P < .005). CONCLUSIONS: Our findings suggest that impairment of the skin's epithelial-moisture barrier function associated with inflammation and development of incontinence-associated dermatitis begins rapidly after an incontinence event, even with the use of a premium pad with wicking technology. Study findings also suggest that prompt attention to incontinence events is needed to prevent moisture-associated skin damage (incontinence-associated dermatitis) even when absorbent pads are used.

Computer Modeling of Prophylactic Dressings: An Indispensable Guide for Healthcare Professionals.

This article is a review of the work conducted and published to date in employing computer finite element (FE) modeling for efficacy research of prophylactic dressings in the context of preventing pressure injuries. The authors strive to explain why FE modeling is essential in establishing the efficacy of prophylactic dressings, as it is in the development and evaluation of any other preventive intervention. In particular, FE modeling provides insights into the interactions between dressing structures and weight-bearing body tissues (including susceptible anatomical locations such as the sacrum and heels of supine patients). Modeling further facilitates reliable visualization and quantification of the mechanical loads that develop in superficial and deep tissues as a result of body weight or external forces based on known physical principles. The modeling then helps to determine how these tissue loads are mitigated using prophylactic dressings of different designs, structures, and material compositions and rate performances of existing or new products.All of the work published so far on modeling the modes of action of prophylactic dressings has focused on the Mepilex Border dressing (Mölnlycke Health Care AB, Gothenburg, Sweden). Published work has revealed several key design features that are pivotal for obtaining successful clinical outcomes, namely, (1) a multilayered alternating-stiffness structure with embedded anisotropy; (2) a minimal friction coefficient at the external surface of the dressing; and (3) low impact of fluid retention on the mechanical behavior of the dressing. These features, their importance, and the methods of identifying their roles in the modes of action of effective prophylactic dressings are detailed here.Computer models clearly inform the process of engineering prophylactic dressings, but they may also provide guidance in clinical use, contribute to assessing technologies and products, support purchasing, and describe product endurance. As the methods of FE modeling of dressings improve, simulations may soon incorporate the simultaneous complex interactions among tissue distortion, heat transfer in tissue, and prophylactic dressings to inform patient care.

New Clinically Relevant Method to Evaluate the Life Span of Prophylactic Sacral Dressings.

It has been demonstrated that wound dressings provide a protective effect against pressure injuries. However, no method exists to measure either the life or performance of dressings used in prevention; testing dressings in a clinical setting or a research environment has typically been based on measuring its moisture absorption capacity. This article examines the changes that occur in the structural and mechanical properties of a prophylactic dressing based on conditions of use when wound exudate is not present.A clinically relevant method was developed to simulate the loading, friction-inducing shear, and moisture transpiration present in a typical hospitalization where a dressing is applied for prevention. Single-use dressings were tested using this method to evaluate their ability to protect patients from pressure injuries throughout the typical 5 to 7 days of use. Following this aging process, researchers measured the physical, structural, and mechanical changes in prophylactic dressings over time.This innovative method provides guidance for clinicians on dressing use and replacement intervals. For bioengineers, the method generates important empirical data for computer modeling of dressing performance, which can then reveal the consequences of changes in dressing structure and function on sustained tissue loads. It is the authors' hope to generate discussion about the creation of industry-wide standards for testing dressings to improve patient care.

Measuring Tensile Strength to Better Establish Protective Capacity of Sacral Prophylactic Dressings Over 7 Days of Laboratory Aging.

Results from large-scale randomized clinical trials support the application of prophylactic dressings to provide protection from body-weight force-induced deformations known to damage skin and underlying tissues, which often result in pressure injuries (pressure ulcers). This laboratory study using a new method for aging dressings in simulated use followed by tensile testing was conducted to further understand the protective effect of sacral prophylactic dressings (SPDs) in alleviating tissue deformations in the sacral region through the course of typical application. Specifically, four SPDs were exposed to a simulation of the clinical environment incorporating saline solution absorption, mechanical loading, and repetitive sliding-induced shear. After aging, the protective endurance of the SPDs was measured through tensile testing to determine their effectiveness against tissue-damaging forces over time.This study uses the concepts of axial stiffness, protective endurance, and elastic limit to describe more accurately the protective aspects of SPDs under dry and moist conditions and how they interact with the skin and underlying tissues over the life of the dressing. The authors propose two primary features in SPD effectiveness in preventing pressure injuries: high conformability (ie, low flexural stiffness) and protective endurance (the dressing's capacity to maintain biomechanical performance when moist).

Microclimate: A critical review in the context of pressure ulcer prevention.

Pressure ulcers are caused by sustained mechanical loading and deformation of the skin and subcutaneous layers between internal stiff anatomical structures and external surfaces or devices. In addition, the skin microclimate (temperature, humidity and airflow next to the skin surface) is an indirect pressure ulcer risk factor. Temperature and humidity affect the structure and function of the skin increasing or lowering possible damage thresholds for the skin and underlying soft tissues. From a pressure ulcer prevention research perspective, the effects of humidity and temperature next to the skin surface are inextricably linked to concurrent soft tissue deformation. Direct clinical evidence supporting the association between microclimate and pressure ulceration is sparse and of high risk of bias. Currently, it is recommended to keep the skin dry and cool and/or to allow recovery periods between phases of occlusion. The stratum corneum must be prevented from becoming overhydrated or from drying out but exact ranges of an acceptable microclimate are unknown. Therefore, vague terms like 'microclimate management' should be avoided but product and microclimate characteristics should be explicitly stated to allow an informed decision making. Pressure ulcer prevention interventions like repositioning, the use of special support surfaces, cushions, and prophylactic dressings are effective only if they reduce sustained deformations in soft tissues. This mode of action outweighs possible undesirable microclimate properties. As long as uncertainty exists efforts must be taken to use as less occlusive materials as possible. There seems to be individual intrinsic characteristics making patients more vulnerable to microclimate effects.

Hazardous Drug Contamination of Drug Preparation Devices and Staff: A Contamination Study Simulating the Use of Chemotherapy Drugs in a Clinical Setting.

Background: Hazardous drug contamination (HD) in healthcare environments continues, placing healthcare staff at risk of significantly chronic health problems, despite the use of personal protective equipment (PPE) and closed system transfer device systems (CSTDs). Objective: This study's aim was to determine how HD might spread through touch after handling contaminated vials in simulated pharmacy and nursing environments. Methods: UV fluorescent powder Glo Germ (Glo Germ Co., Moab, UT), composed of melamine resin, was used to simulate HD. Following manufacturer's exact usage specifications, five commercially available CSTDs were tested in the simulated pharmaceutical preparation environment under controlled conditions. UV fluorescence was used to detect the test medium powder that simulated HD following each trial. Photographs, using a Nikon D40X (10.2 mp) camera, were taken at selected stages of testing to document the presence of HD. Results: Transfer of the HD testing medium (Glo Germ) to IV sets, pharmacy PPE, and nursing PPE was observed in 4 of 5 CSTDs tested. The only CSTDs that showed no observable contamination was the Allison Medical Safety Enclosed Vial Adapter (SEVA) system (Littleton, CO). Conclusions: Results show residue from HD vials spread as vial was handled in a pharmacy environment in 4 of 5 CSTDs, contaminating pharmacy PPE, ancillary products, and nursing PPE. No HD residue was detected on PPE, ancillary products, or nursing PPE in the pharmacy after using the SEVA system, providing an effective means to contain HD for drug transfer from vial to delivery system.

Off loading wheelchair cushion provides best case reduction in tissue deformation as indicated by MRI.

Off-loading or the Orthotic approach to wheelchair seating has been used successfully to provide seating that optimizes tissue protection at the ischial tuberosities (ITs), sacrum and greater trochanters. Recent publications indicate the significance of preventing tissue compression to reduce ulcer formation. Comparative Magnetic Resonance Imaging (MRI) of individuals seated on two cushion types provides direct evidence of tissue unloading resulting in the reduction in tissue compression. Measurement of tissue compression in MRI images provides the cumulative impact of compression and shear resulting in ultimate tissue thickness documented here. In this study's application of MRI to off-loading cushions (OLC), an alternate form of tissue protection was observed. Instead of incorporating immersion and envelopment, loads were transferred from high-risk areas, such as bony prominences, to lower risk soft tissues. This method shows both shearing and compression of load bearing tissues in seated individuals with the OLC in place. Tissue thickness measurements determined by MRI analysis indicate that the OLC provides greater reduction in tissue deformation than the air cell cushion (ACC). Deformation of tissues loaded by the OLC is not significantly different from the deformations seen with the ACC. This research represents the first reported use of MRI to document the comparative off-loading capabilities of two cushions and the resultant tissue compression and ulceration risk. While MRI analysis may not be incorporated in daily cushion prescription, this paper proposes a methodology in which MRI analysis of tissue deformation on comparative cushions allows the determination of best-case cushion selection for reduction of ischial pressure ulcer (PU) risk.

Orthotic-Style Off-Loading Wheelchair Seat Cushion Reduces Interface Pressure Under Ischial Tuberosities and Sacrococcygeal Regions.

OBJECTIVE: To assess the efficacy of an off-loading wheelchair seat cushion in removing pressure from high-risk ischial tuberosities and the coccyx/sacrum in wheelchair sitting. DESIGN: Repeated-measures design. SETTING: Private research laboratory. PARTICIPANTS: Manual wheelchair users with chronic spinal cord injuries (N=10). INTERVENTIONS: Three configurations of an off-loading wheelchair seat cushion compared with a flotation style (10-cm air inflation) wheelchair seat cushion. MAIN OUTCOME MEASURES: Outcome measures included peak pressure index (PPI), ischial tuberosity peak pressures, and the dispersion index or ratio of pressures under the ischial and sacral regions to the total of all pressures recorded. RESULTS: PPI and ischial tuberosities peak pressure ranged from a low of 39±18 and 68±46mmHg in the fully off-loaded cushion to a high of 97±30 and 106±34mmHg, respectively, for the flotation style cushion (2-way analysis of variance main effect across 4 conditions, P<.001). Dispersion index ranged from a low of 8%±3% in the fully off-loaded cushion to a high of 16%±3% in the flotation style cushion. Pairwise comparisons yielded significance in all cushion-pair analyses (P<.05 after multiple corrections). CONCLUSIONS: The force-removal approach of this orthotic off-loading cushion design effectively reduces a known extrinsic risk factor for pressure ulcers-interface pressure-in the high-risk ischial tuberosity and sacral/coccygeal regions of the buttocks.

Standardizing Support Surface Testing and Reporting: A National Pressure Ulcer Advisory Panel Executive Summary.

In 2001, the National Pressure Ulcer Advisory Panel's Research Committee identified the need to create uniform terminology, test methods, and reporting technical standards for support surfaces. As a result, the S3I Committee was formed and initial meetings of interested stakeholders who included clinicians, researchers, academics, manufacturers, providers, and regulators were held. The group's initial goal was to (1) establish common language to facilitate understanding by developing standardized terminology for describing and discussing support surfaces, (2) establish a suite of standardized tests of performance capable of repeatedly, reliably, and accurately reporting upon characteristics common to all support surfaces that are believed to be related to the extrinsic risk factors associated with skin breakdown, as indicated by the literature to date, and (3) identify and standardize methods to evaluate the effective life of a support surface. The purpose of this article was to summarize the current status of the effort of the Support Surface Standards Initiative (S3I) Committee to identify and standardize methods to evaluate the many characteristic factors that determine the effective life of a support surface.

Applying ISO 16840-2 Standard to differentiate impact force dissipation characteristics of selection of commercial wheelchair cushions.

Results from applying the International Organization for Standardization (ISO) 16840-2 test method for determining the impact damping characteristics of 35 wheelchair cushions plus a high resilience (HR70) polyurethane reference foam sample are reported. The generation of impact forces when a wheelchair user either transfers onto a cushion or the wheelchair encounters rough terrain or bumps down a step can endanger the viability of tissues, especially if these forces occur repeatedly. The results demonstrate significant differences in the impact force dissipation characteristics of different cushion products but do not reliably identify differences in performance that can be attributed to descriptive information about cushion composition alone. Instead, these results demonstrate that the materials, proprietary design, and construction features of wheelchair cushions in combination dictate impact force dissipation properties. The results of a cluster analysis are used to generate a model that can be used to compare the impact damping properties obtained from the ISO 16840-2 test method with those of a range of cushions and the reference cushion. Manufacturers will therefore be able to provide users and clinicians with information about the impact force dissipation properties of the cushions that will enable them to make more informed product choices for achieving improved comfort and to protect skin integrity.

Failure to Reposition After Sliding Down in Bed Increases Pressure at the Sacrum and Heels.

UNLABELLED: The head of the bed (HOB) for a patient is often elevated since it improves comfort and facilitates respiratory functions. However, elevating the HOB essentially causes the patient support surface to turn into a ramp, forcing the patient's body to slide down. As the patient slides down, weight pressing on the pelvis, the coccyx, and the ischial tuberosities increases, resulting in associated increases in interface pressures. METHODS: In an institutional review board-approved study, pressure distribution was measured on volunteers at 4 discrete body positions sliding down in bed on 3 commonly used support surfaces. RESULTS: This study showed the total contact area of the patients decreased as they slid down, resulting in increased pressure, particularly on the sacral area and the heels. The study also confirmed that these pressure increases are persistent and occurred on all of the support surfaces tested. CONCLUSION: These increases in pressure likely contribute to the development of pressure ulcers.