Associations between body mass index and interface pressure after 3 h loading in healthy adults.

AIM OF THE STUDY: The purpose of this study was to determine the associations between body mass index and interface pressure after 3 h loading in healthy adults and to establish a foundation for the development of interventions tailored to body mass index. MATERIAL AND METHODS: A secondary data analysis based on a clinical trial involving 75 adults was conducted. Data were analyzed using descriptive statistics, repeated measure ANOVA, and ANCOVA. The statistics program IBM SPSS Statistics 27.0 was used for data analysis. RESULTS: Loading caused a significant increase in average pressure in the obesity group compared to the underweight group. There was a significant increase in risk area ratio calculated based on 30 mmHg and 45 mmHg in both obesity and overweight groups compared to the underweight group. On both support surfaces, average pressure, peak pressure, and risk area ratio were higher in the obese group compared to the normal weight group. However, these differences were not statistically significant. CONCLUSION: Given the emphasized risk of pressure injuries, long-term observation of body mass index-specific changes in interface pressure can provide crucial evidence for pressure injury prevention nursing. The results of this study suggest the need to implement pressure injury prevention interventions that consider the pressure characteristics according to BMI.

Prediction of tissue deformation based on mechanical and physiological factors in the prone position during surgery.

AIM: This study aimed to predict tissue deformation based on the pressure applied while lying in the prone position and physiological factors. METHODS: Healthy volunteers were instructed to lie on mattresses of four different hardness levels (50, 87.5, 175, and 262.5 N). The order in which the mattresses were used was randomized per participant. Pressure at the iliac crests was measured using a pressure mapping sensor sheet. Participants were placed in the prone position for 10 min, with pressure data used from the latter 5 min. For the tissue deformation at the iliac crests, our previous study data were used. Multiple regression analysis was used to identify predictive mechanical and physiological factors. RESULTS: The distance between the left and right greater trochanters, maximum interface pressure and age were significant predictors for compression of the skin and soft tissue. Significant predictors of internal soft tissue displacement were the distances between the left and right anterior superior iliac spines and greater trochanters. No factors predicted skin surface displacement. CONCLUSIONS: Our study provided predictive factors that may be measured easily in a clinical setting to reduce the risk of pressure ulcers during surgery in the prone position.

Validation of a Custom Interface Pressure Measurement System to Improve Fitting of Transtibial Prosthetic Check Sockets.

Achievement of fit between the residual limb and prosthetic socket during socket manufacture is a priority for clinicians and is essential for safety. Clinicians have recognised the potential benefits of having a sensor system that can provide objective socket-limb interface pressure measurements during socket fitting, but the cost of existing systems makes current technology prohibitive. This study will report on the characterisation, validation and preliminary clinical implementation of a low cost, portable, wireless sensor system designed for use during socket manufacture. Characterisation and benchtop testing demonstrated acceptable accuracy, behaviour at variable temperature, and dynamic response for use in prosthetic socket applications. Our sensor system was validated with simultaneous measurement by a commercial sensor system in the sockets of three transtibial prosthesis users during a fitting session in the clinic. There were no statistically significant differences between the sensor system and the commercial sensor for a variety of functional activities. The sensor system was found to be valid in this clinical context. Future work should explore how pressure data relates to ratings of fit and comfort, and how objective pressure data might be used to assist in clinical decision making.

Quantification of Comfort for the Development of Binding Parts in a Standing Rehabilitation Robot.

Human-machine interfaces (HMI) refer to the physical interaction between a user and rehabilitation robots. A persisting excessive load leads to soft tissue damage, such as pressure ulcers. Therefore, it is necessary to define a comfortable binding part for a rehabilitation robot with the subject in a standing posture. The purpose of this study was to quantify the comfort at the binding parts of the standing rehabilitation robot. In Experiment 1, cuff pressures of 10-40 kPa were applied to the thigh, shank, and knee of standing subjects, and the interface pressure and pain scale were obtained. In Experiment 2, cuff pressures of 10-20 kPa were applied to the thigh, and the tissue oxygen saturation and the skin temperature were measured. Questionnaire responses regarding comfort during compression were obtained from the subjects using the visual analog scale and the Likert scale. The greatest pain was perceived in the thigh. The musculoskeletal configuration affected the pressure distribution. The interface pressure distribution by the binding part showed higher pressure at the intermuscular septum. Tissue oxygen saturation (StO2) increased to 111.9 ± 6.7% when a cuff pressure of 10 kPa was applied and decreased to 92.2 ± 16.9% for a cuff pressure of 20 kPa. A skin temperature variation greater than 0.2 °C occurred in the compressed leg. These findings would help evaluate and improve the comfort of rehabilitation robots.

Sacral interface pressure can be alleviated by repositioning with a small-angle change using an automated bed in patients with spinal cord injury.

AIM OF THE STUDY: This study aimed to compare interface pressure and total contact area of the sacral region in different positions, including small-angle changes, in patients with spinal cord injury (SCI). Furthermore, we analyzed the clinical factors influencing pressure to identify the pressure injury (PI) high-risk group. MATERIALS AND METHODS: An intervention was conducted for patients with paraplegia (n = 30) with SCI. In the first and second trials, interface pressure and total contact area of the sacral region were recorded from large- and small-angled positions using the automatic repositioning bed, which can change the angle of the back, lateral tilt, and knee. RESULTS: Positions with back raised ≥45° showed significantly higher pressure on the sacrum than most other positions. The pressure and contact area differences were statistically insignificant for combinations of small-angled changes <30°. Additionally, the duration of injury (ß = 0.51, p = 0.010) and neurological level of injury (NLI) (ß = -0.47, p = 0.020) were significant independent predictors of average pressure. Similarly, the duration of injury (ß = 0.64, p = 0.001), the Korean version of the spinal cord independence measure-III (ß = -0.52, p = 0.017), and body mass index (BMI; ß = -0.34, p = 0.041) were significant independent predictors of peak pressure. CONCLUSIONS: For repositioning, combinations of small-angle changes <30° effectively reduce pressure on the sacral region in patients with SCI. Lower BMI, longer duration of injury, lower functioning score, and NLI ≥ T7 are predictors of high sacral pressures, which increase the risk for PI. Therefore, patients with these predictors require strict management.

Effect of mattress bedding layer structure on pressure relief performance and subjective lying comfort.

Mattresses' pressure relief performance and comfort largely affect sleep quality. Mattress filling materials have been proven to affect the interface pressure distribution and comfort, but the effect of mattress structure is unclear. In this paper, the interface pressure distribution and subjective comfort of 10 subjects were assessed in the different bedding layer structures of mattresses, after mattress support performance was tested. The results show that the mattresses with bedding material hardness gradually increasing from the top layer to the bottom layer (BMH-ITTB) structure have a softer surface layer, a better support core layer, and higher fitness. This enables the mattress to achieve a better decompression effect. The low-pressure area (PAI≤0.67kPa) increased, while the high-pressure area (PAI≥2.67kPa and PAI≥4.00kPa), maximum pressure (P95), average pressure (P50), and pressure index (PI) decreased. This also enables the mattress to achieve higher subjective comfort scores.

Relationship between mattress internal air pressure and interface pressure distribution in the lateral position.

Previous research shows that maximum interface pressure increases when the patient is lying in the lateral position. However, it was unclear whether it was better to increase or decrease the internal air pressure to reduce the maximum interface pressure in the lateral position; thus, this study investigated this issue. In this study, we investigated the change in pressure redistribution because of the difference in internal air pressure between the supine and lateral positions on an active air mattress for pressure ulcer prevention management. Each participant's five internal air pressure values served as the independent variables. The interface pressure on the active air mattress was measured for 20 minutes. The sacral left iliac crest and left greater trochanteric interface pressures were measured using a portable pressure-measuring device. When seven of the 10 participants switched from the supine position to the left lateral position, there was a decrease in the maximum interface pressure as the internal air pressure increased. The maximum interface pressure in the greater trochanter in the lateral position was twice that in the sacral region in the supine position. These results show that increasing the internal air pressure in the lateral position might help reduce the maximum interface pressure.

Key Components Related to Pressure Injury Formation: An Initial Investigation Into Pressure Distribution and Blood Perfusion Responses in Wheelchair Users.

Soft tissue around bony prominences in the buttocks and back are high-risk areas prone to the development of pressure injuries. From a clinical perspective, prevention of pressure injuries all together is the ideal situation. Unfortunately, prevalence rates still reach 47% with recurrence rates even higher. The goals of this study were to evaluate the effects of a series of wheelchair movements, some that currently exist in commercial wheelchairs and some new, on interface pressures and perfusion under the buttocks. Twenty-seven chair positions were obtained by varying back recline, seat pan tilt, and articulation of two supports along the back. Although back recline is commonly taught by therapists to be used as a pressure relieving posture, results indicated an increase in pressures under the ischial tuberosities and sacral areas in reclined positions. Articulation of the back supports produced changes in posture moving from an "erect" to "slouched" position. These movements successfully shifted pressures across back regions. Seat pan tilt was effective in shifting pressures off the ischial tuberosity regions. Additionally, in a portion of the participants, seat pan tilt consistently increased perfusion under the ischial tuberosity region. The findings of this research suggest that movements other than back recline should be considered to more effectively alter interface pressures, particularly in high-risk regions like the sacrum and ischial tuberosities.

Comparing the Interface pressure distribution of the full body chest-lumbar cushion made of memory cotton with the traditional chest cushion.

BACKGROUND: Pressure injuries are common complications occurred duration hospitalization, whether the interface pressure distribution in full body memory cotton chest-lumbar cushion was superior than traditional chest cushion remains unclear. PURPOSE: This study aimed to compare the effects that the full body memory cotton chest-lumbar cushion versus traditional chest cushion on interface pressure. METHODS: A total of 66 healthy individuals were recruited. The volunteers were placed in the left lateral position and left armpit and iliac spine pressure and level of comfort were measured. Group differences were assessed using the paired t-test or Wilcoxon test according to data distribution. Additionally, multivariate regression analysis was applied to determine the potential role of sex, age, and body mass index on left armpit and iliac spine pressure and overall comfort. RESULTS: Compared with the traditional chest cushion, we noted that the full body chest-lumbar cushion made of memory cotton was associated with less pressure on the left armpit (38.17 ± 10.39 mmHg vs. 67.93 ± 14.67 mmHg, respectively; P < 0.0001) and iliac spine (43.32 ± 13.70 mmHg vs. 50.77 ± 20.94 mmHg, respectively; P = 0.0004). Moreover, we noted that the overall comfort with the memory cotton chest-lumbar cushion was higher than that with the traditional chest cushion (8.48 ± 1.08 vs. 6.36 ± 1.45, respectively; P < 0.0001). Finally, the multivariate regression analyses found iliac spine pressure could affect by sex (P = 0.0377) and body mass index (P = 0.0380). CONCLUSIONS: The full body chest-lumbar cushion made of memory cotton had beneficial effects on left armpit and iliac spine pressure and on comfort. These findings should be applied to future clinical practice.

Effect of interface pressure and skin surface temperature on pressure injury incidence: a turning schedule pilot study.

OBJECTIVE: This study aimed to evaluate the interface pressure and skin surface temperature in relation to the incidence of pressure injury (PI) using three different turning schedules. METHOD: This was a pilot study with a three-armed randomised clinical trial design. Participants at risk of PI and treated in the high dependency care unit in a regional hospital in Makassar, Indonesia participated in this study. Patients were repositioned at three different turning schedules (two-, three- and four-hourly intervals). Interface pressure measurement and skin surface temperature were measured between 14:00 and 18:00 every three days. The incidence of PI was assessed during the two-week observation period. RESULTS: A total of 44 participants took part in the study. A one-way ANOVA test revealed no difference in interface pressure among the three different turning schedule groups within two weeks of observations: day zero, p=0.56; day four, p=0.95; day seven, p=0.56; day 10, p=0.63; and day 14, p=0.92. Although the average periumbilical temperature and skin surface temperature were not significant (p>0.05), comparison between these observation sites was significant on all observation days (p<0.05). Regarding the incidence of PI, the proportional hazard test for the development of PI in the three groups was considered not different (hazard ratio: 1.46, 95% confidence interval: 0.43-4.87, p=0.54). CONCLUSION: No difference in interface pressure and incidence of PI on the three turning schedules was observed; however, there was a potential increase in skin surface temperature in comparison with periumbilical temperature for all three turning schedules.

Assessing Post-Driving Discomfort and Its Influence on Gait Patterns.

Professional drivers need constant attention during long driving periods and sometimes perform tasks outside the truck. Driving discomfort may justify inattention, but it does not explain post-driving accidents outside the vehicle. This study aims to study the discomfort developed during driving by analysing modified preferred postures, pressure applied at the interface with the seat, and changes in pre- and post-driving gait patterns. Each of the forty-four volunteers drove for two hours in a driving simulator. Based on the walking speed changes between the two gait cycles, three homogeneous study groups were identified. Two groups performed faster speeds, while one reduced it in the post-steering gait. While driving, the pressure at the interface and the area covered over the seat increased throughout the sample. Preferred driving postures differed between groups. No statistical differences were found between the groups in the angles between the segments (flexed and extended). Long-time driving develops local or whole-body discomfort, increasing interface pressure over time. While driving, drivers try to compensate by modifying their posture. After long steering periods, a change in gait patterns can be observed. These behaviours may result from the difficulties imposed on blood circulation by increasing pressure at this interface.

Relationship Between Interface Pressures and Pneumatic Cuff Inflation Pressure at Different Assessment Sites of the Lower Limb to Aid Soft Exoskeleton Design.

OBJECTIVE: The aim was to develop a means of predicting interface pressure from cuff inflation pressure during circumferential compression at the lower limb, in order to inform the design of soft exoskeletons. BACKGROUND: Excessive mechanical loading of tissues can cause discomfort and soft tissue injury. Most ergonomic studies on exoskeletons are of interface pressure, but soft exoskeletons apply circumferential pressures similar to tourniquet cuffs by way of cuff inflation pressure. This study details the relationship between interface and cuff inflation pressures for pneumatic tourniquet cuffs. METHOD: Pneumatic cuffs of different widths were inflated to target pressures on (A) a rigid cylinder, (B) the dominant thigh and calf, and (C) knee of healthy participants standing still. Interface pressures were measured under the cuffs using a pressure-sensing mat. Average interface pressures were then compared to cuff inflation pressures. The influence of cuff width, cuff inflation pressure, and participants' anthropometric data on pressure transmission was assessed. RESULTS: A strong linear relationship between cuff inflation pressures and interface pressures was observed. Interface pressures were generally higher than cuff inflation pressures. The efficiency of pressure transmission to the lower limb depended on assessment site, adipose tissue thickness, cuff size, cuff inflation pressure, and possibly limb circumference. Regression equations were developed to predict interface pressures at the thigh, calf, and knee. CONCLUSION: Interface pressures under pneumatic cuffs are influenced by the cuff size, cuff inflation pressure, and tissue compressibility. Predicted interface pressure from cuff inflation pressure and vice versa can be used to aid the design of soft exoskeletons.

A randomized controlled trial to compare the interface pressures of alternating pressure overlay with gel pad versus gel pad alone during prolonged surgery.

INTRODUCTION: Prolonged surgery is a known risk of pressure ulcer formation. Pressure ulcers affect the quality of life, are a significant cause of morbidity and mortality, and pose a burden on the healthcare system. This study aimed to compare the effectiveness of an alternating pressure (AP) overlay with Gel pad against the Gel pad in reducing interface pressure (IP) during prolonged surgery. METHODS: A total of 180 participants from a tertiary hospital were randomized to AP overlay with Gel pad group (n = 90) and Gel pad group (n = 90). Patients were placed supine on the pressure redistributing surfaces, and IP data under the sacrum and ischial tuberosities were collected at an interval of 30 min from 0 min up to a maximum of 570 min. RESULTS: Based on data from 133 participants, the average IPs during all the deflation cycles of the AP overlay (with Gel pad) were significantly lower than the average continuous IP recorded for Gel pad throughout the measuring period (p < 0.001). Only three patients (2.26% of study participants) - Gel pad group (n = 2; 2.99%) and AP overlay with Gel pad group (n = 1; 1.52%) developed post-operative pressure ulcer (p = 0.5687). CONCLUSIONS: The lower IP during deflation cycles of the AP overlay (with Gel pad) suggests its potential effectiveness in preventing pressure ulcer formation in patients undergoing prolonged surgery. The prevention and reduction of pressure ulcers will have a considerable impact on the improved quality of life and cost savings for the patient. The study findings may facilitate the formulation of policies for preventing pressure ulcer development in the perioperative setting.

Study of Three Interface Pressure Measurement Systems Used in the Treatment of Venous Disease.

The aim of the publication is to report the accuracy, repeatability and the linearity of three commercially available interface pressure measurement systems employed in the treatment of venous disease. The advances in the treatment and management of chronic venous disease by compression therapy have led to considerable research interest in interface pressure measurement systems capable of measuring low-pressure ranges (10-60 mmHg). The application of a graduated pressure profile is key for the treatment of chronic venous disease which is achieved by using compression bandages or stockings; the required pressure profiles are defined in standards (BSI, RAL-GZ, or AFNOR) for different conditions. However, achieving the recommended pressure levels and its accuracy is still deemed to be a challenge. Thus, it is vital to choose a suitable pressure measurement system with high accuracy of interface pressure. The authors investigated the sensing performance of three commercially available different pressure sensors: two pneumatic based (AMI and PicoPress®) and one piezoresistive (FlexiForce®) pressure sensors, with extensive experimental work on their performance in terms of linearity, repeatability, and accuracy. Both pneumatic based pressure measurement systems have shown higher accuracy in comparison to the flexible piezoresistive pressure sensors.

[Innovations in medical compression therapy]. / Innovationen der medizinischen Kompressionstherapie.

For the treatment of phlebological and lymphological diseases as well as constitutional edema diseases, a discussion of innovative concepts of medical compression therapy is essential. It is recommended that medical compression stockings should always be prescribed based on symptoms and with the lowest effective interface pressure to optimize the tolerability of compression therapy. Likewise, medical compression stockings with an integrated care formula, but also the application of additional skincare can improve the quality of life and compliance in patients with chronic venous insufficiency. Optimization of ulcer therapy can be achieved by using two-component compression stocking systems. These consist of an understocking and a firm outer compression stocking, which improve the venous and capillary hemodynamics with good wearing comfort and lead to the healing of venous ulcerations. Multicomponent compression bandages and short stretch bandages are proven in the decongestion phase of edema. Multicomponent bandages ensure a sustained interface pressure for at least 5 days and are ideal for outpatient treatment with less frequent dressing changes. For compression therapy in patients with arterial-venous leg ulcers (ABI [ankle brachial index] >0.5), specially developed "lite" versions of the multicomponent dressings can be used.

Compression therapy in venous diseases: physical assumptions and clinical effects.

Compression therapy (CT) is an established treatment method in chronic venous disease. Despite years of clinical experience, choosing the optimum compression therapy, including grade and pressure distribution, which determine the efficacy of treatment poses a challenge. The paper discusses CT physical assumptions (stiffness, elasticity, static and dynamic stiffness indices), clinical effects and contraindications to CT.

A Wearable Compression Device to Normalise Calf Muscle Pump Function in Chronic Venous Insufficiency for Each Postural Position.

BACKGROUND: For the currently used compression therapy, the applied compression pressure is usually inadequate to exert an effective impact on the veins in different body positions. The aim was to assess the venous ejection fraction achieved by a new compression device which automatically adjusts the interface pressure to body position in an acute experimental setting. METHODS: A new portable, battery driven compression device providing pressure adjusted to allow for body position, and connected to a less or very stiff calf cuff wrap was tested. In patients with superficial venous incompetence, the ejection fraction (EF) of the calf pump was measured by strain gauge plethysmography. Applied in a random sequence, values achieved without compression, with the two cuffs, and with compression stockings exerting 23-32 mmHg, were compared. The applied compression pressures were simultaneously recorded in the supine and standing positions, and during walking. Comfort was assessed by a visual analogue scale (VAS) with 0 corresponding to very low comfort and 10 to very comfortable. RESULTS: In 16 patients with CEAP clinical stage C3-C6, EF without compression was 37%, increasing to 46.9% with stockings, to 64.8% (p < .001) by less stiff and to 75.5% (p < .001) by stiffer wraps. The median interface pressure (supine/standing) was 31/56 mmHg for the less stiff device, 32/68 mmHg for the stiffer device, and 23/26 mmHg for the stockings. The static stiffness index and the walking pressure amplitudes were significantly higher than those generated by the stocking, and the highest values were found with the stiffer wrap material. The device comfort was high both in the supine and standing positions (VAS 8 ± 2). CONCLUSIONS: The tested devices were comfortable at rest and haemodynamically effective during walking by automatically adjusting compression pressures to body position. They are significantly more effective than elastic stockings in improving EF. The system is able to overcome the problems of fast pressure loss by continuously re-adjusting the compression pressure.

Biomechanical analysis of different dynamic sitting techniques: an exploratory study.

Prolonged static sitting in wheelchairs increases the risk of pressure ulcers. This exploratory study proposed three dynamic sitting techniques in order to reduce the risk of developing pressure ulcer during wheelchair sitting, namely lumbar prominent dynamic sitting, femur upward dynamic sitting, and lumbar prominent with femur upward dynamic sitting. The purpose of this study was to analyze the biomechanical effects of these three techniques on interface pressure. 15 able-bodied people were recruited as subjects to compare the aforementioned sitting techniques in a random order. All parameters, including dynamic contact area, dynamic average pressure, and dynamic peak pressure on backrest and seat were measured and compared. In result, when compared with lumbar prominent dynamic sitting, femur upward dynamic sitting and lumbar prominent with femur upward dynamic sitting appeared to yield significantly lower dynamic average and peak pressure on the back part of seat, and significantly higher dynamic average and peak pressure on the front part of seat. This study can serve as a reference point for clinical physicians or wheelchair users to identify a suitable dynamic sitting technique.

Evaluation of Force Sensing Resistors for the Measurement of Interface Pressures in Lower Limb Prosthetics.

Understanding the pressure distributions at the limb-socket interface is essential to the design and evaluation of prosthetic components for lower limb prosthesis users. Force sensing resistors (FSRs) are employed in prosthetics research to measure pressure at this interface due to their low cost, thin profile, and ease of use. While FSRs are known to be sensitive to many sources of error, few studies have systematically quantified these errors using test conditions relevant to lower limb prosthetics. The purpose of this study was to evaluate FSR accuracy for the measurement of lower limb prosthetics interface pressures. Two FSR models (Flexiforce A201 and Interlink 402) were subjected to a series of prosthetic-relevant tests. These tests included: (1) static compression, (2) cyclic compression, and (3) a combined static and cyclic compression protocol mimicking a variable activity (walk-sit-stand) procedure. Flexiforce sensors outperformed Interlink sensors and were then subjected to two additional tests: (4) static curvature and (5) static shear stress. Results demonstrated that FSRs experienced significant errors in all five tests. We concluded that: (1) if used carefully, FSRs can provide an estimate of prosthetic interface pressure, but these measurements should be interpreted within the expected range of possible measurement error given the setup; (2) FSRs should be calibrated in a setup that closely matches how they will be used for taking measurements; and (3) both Flexiforce and Interlink sensors can be used to estimate interface pressures; however, in most cases Flexiforce sensors are likely to provide more accurate measurements.

Interface pressures with compression systems: relevance to clinical practice.

Interface pressures with compression depend on many factors relating to the science of measurement and intrinsic, patient-related factors, including limb size and tissue texture. While it is important for manufacturers of compression devices to measure pressures, it may not always be relevant to clinical practice where application methods and oedematous limbs may affect final pressures. Accurate performance of any compression system relies on the use of the right technology for the right condition and patient lifestyle. Correct application following training and in accordance with instructions for use may be adapted according to individual patient comfort and needs, including mobility, tissue texture and the stage of management. In order to provide treatment regimens that are safe, effective and well tolerated by patients, as well as being easy to apply and demonstrate sound economic practice, science needs to meet clinical practice. Patient reporting is an important for successful treatment, matching clinical effectiveness with patient acceptance during reassessment and monitoring.