Designing pressure garments capable of exerting specific pressures on limbs

Pressure garments have been used prophylactically and to treat hypertrophic scars, resulting from serious burns, since the early 1970s. They are custom-made from elastic fabrics by commercial producers and hospital staff. However, no clear scientifically established method has ever been published for their design and manufacture. Previous work [2] identified the most commonly used fabrics and construction methods for the production of pressure garments by hospital staff in UK burn units. These methods were evaluated by measuring pressures delivered to both cylinder models and to human limbs using I-scan pressure sensors. A new calibration method was developed for the I-scan system to enable measurement of low interface pressures to an accuracy of +/-2.5 mmHg. The effects of cylinder/limb circumference and pressure garment design on the pressures exerted were established. These measurements confirm the limitations of current pressure garment construction methods used in UK hospitals. A new method for designing pressure garments that will exert specific known pressures is proposed and evaluated for human thighs. Evaluation of the proposed design method is ongoing for other body parts.     

Pressure garment design tool to monitor exerted pressures

Pressure garments are used in the treatment of hypertrophic scarring following serious burns. The use of pressure garments is believed to hasten the maturation process, reduce pruritus associated with immature hypertrophic scars and prevent the formation of contractures over flexor joints. Pressure garments are normally made to measure for individual patients from elastic fabrics and are worn continuously for up to 2 years or until scar maturation. There are 2 methods of constructing pressure garments. The most common method, called the Reduction Factor method, involves reducing the patient's circumferential measurements by a certain percentage. The second method uses the Laplace Law to calculate the dimensions of pressure garments based on the circumferential measurements of the patient and the tension profile of the fabric. The Laplace Law method is complicated to utilise manually and no design tool is currently available to aid this process. This paper presents the development and suggested use of 2 new pressure garment design tools that will aid pressure garment design using the Reduction Factor and Laplace Law methods. Both tools calculate the pressure garment dimensions and the mean pressure that will be exerted around the body at each measurement point. Monitoring the pressures exerted by pressure garments and noting the clinical outcome would enable clinicians to build an understanding of the implications of particular pressures on scar outcome, maturation times and patient compliance rates. Once the optimum pressure for particular treatments is known, the Laplace Law method described in this paper can be used to deliver those average pressures to all patients. This paper also presents the results of a small scale audit of measurements taken for the fabrication of pressure garments in two UK hospitals. This audit highlights the wide range of pressures that are exerted using the Reduction Factor method and that manual pattern ‘smoothing’ can dramatically change the actual Reduction Factors used.     

Reproducibility of repeated measurements with the Kikuhime pressure sensor under pressure garments in burn scar treatment

This study investigated the reproducibility of repeated measurements with the Kikuhime pressure sensor under two different types of pressure garments used in the treatment and prevention of scars after burns. Also efficiency of garments was assessed in clinical circumstances by assessing pressure loss and residual pressure after 1 month. Intra- and inter-observer reproducibility and repeated measurements with 1-month time lapse were examined on 55 sites in 26 subjects by means of intra-class correlation coefficients and standard error of measurements. Results showed good to excellent ICC and low SEMs in the two conditions. There was a significant difference in pressure after 1 month between elastic tricot and weft knit garments, although evolution of pressure loss after 1 month was similar. Concerning different locations, there was a significant difference in pressure loss after 1 month between gloves and sleeves with the largest pressure loss for sleeves. Considering these results we concluded that the Kikuhime pressure sensor provides valid and reliable information and can be used in comparative clinical trials to evaluate pressure garments used in burn scar treatment. Secondly, elastic tricot garments in our study tended to have higher clinical pressures but both types of garments had similar pressure loss over time.     

Comparison between the portable pressure measuring device and PicoPress® for garment pressure measurement on hypertrophic burn scar during compression therapy

PurposeThe current standard treatment for hypertrophic scars following burn injury is pressure garment therapy. The experimenters developed the novel portable pressure measuring device using silicon piezoresistive sensors. As PicoPress® is the most accurate (i.e., lowest variation and error) manometric sensor for pressure measurement, we sought to compare and examine the accuracy of the novel device regarding in vitro pressure measurements at the hypertrophic scar–pressure garment interface.MethodsThe novel device was designed to operate in non-corrosive media, such as air. The device can use up to six pressure sensing points and was developed to adjust the number of pressure sensors according to the size of the scar. Pressure measurements were acquired through a readout circuit consisting of an analog-to-digital converter, a microprocessor, and a Bluetooth transmission module for wireless data transmission to an external device. All signals were converted into mean pressure expressed in millimeters of mercury (mmHg). The mean pressure values measured by the sensors were compared to those obtained from PicoPress®. 55 garment pressures recordings were obtained from the sensors over this study conducted in 2018–February 2020. We then analyzed the test–retest reliability using the intraclass correlation coefficients (ICC). PicoPress® was also employed in the same pressure garments for obtaining similar measurements. A two way random effects model ICC with 95% confidence intervals was used to compare the mean pressure values obtained from the silicon piezoresistive sensors to the PicoPress® measurements.ResultsThe test–retest reliability of the pressure sensors was close to the acceptable level for clinical use regarding stationary interface pressure measurement (ICC = 0.99, 95% CI 0.990−0.997). The mean pressure obtained from the silicon piezoresistive pressure sensors showed an accordance with the measurements from PicoPress® (ICC = 0.97, 95% CI 0.947−0.985).ConclusionThe novel device may present a viable alternative to PicoPress® for garment pressure measurements. In addition, the novel device improves adaptability to the hypertrophic scar shape and size. Complementary characteristics such as wireless transmission to an external device may allow burn patients to continuously wear the device for real-time measurements during pressure garment therapy, thus improving existing devices including PicoPress®.     

Pressure therapy in the treatment of post-burn hypertrophic scar—A critical look into its usefulness and fallacies by pressure monitoring

Pressure therapy is generally accepted as the best non-invasive means of preventing and controlling hypertrophic scarring after burn injury. Most studies in the past have failed to correlate clinical response with magnitude of the garment-scar interface pressure.This study looked critically at our usual techniques of pressure therapy using pressure ‘sensors’ manufactured locally and based on electro-pneumatic principles. Many pitfalls, such as large variations of pressure at different geometric sites on the body, elastic deterioration in garments, problems of garment manufacture, and the unfavourable properties of the Lycra garments, were observed. Recommendations on pressure treatment were made based on our experiences, to improve the present technique of pressure therapy. These included the standardization of measurement techniques and garment tailoring, the regular checking of pressure at the garment-scar interface using pressure transducers, the appropriate garment adjustments, a strict regimen for garment wearing, and the intelligent use of pressure-padding and reinforcement. Areas of further research are also discussed.     

Re‐evaluation of Pre‐pump Arterial Pressure to Avoid Inadequate Dialysis and Hemolysis: Importance of Prepump Arterial Pressure Monitoring in Hemodialysis Patients

Prepump arterial pressure (PreAP) is monitored to avoid generating excessive negative pressure. The National Kidney Foundation K/DOQI clinical practice guidelines for vascular access recommend that PreAP should not fall below ?250 mm Hg because excessive negative PreAP can lead to a decrease in the delivery of blood flow, inadequate dialysis, and hemolysis. Nonetheless, these recommendations are consistently disregarded in clinical practice and pressure sensors are often removed from the dialysis circuit. Thus far, delivered blood flow has been reported to decrease at values more negative than ?150 mm Hg of PreAP. These values have been analyzed by an ultrasonic flowmeter and not directly measured. Furthermore, no known group has evaluated whether PreAP‐induced hemolysis occurs at a particular threshold. Therefore, the aim of this study was to clarify the importance of PreAP in the prediction of inadequate dialysis and hemolysis. By using different diameter needles, human blood samples from healthy volunteers were circulated in a closed dialysis circuit. The relationship between PreAP and delivered blood flow or PreAP and hemolysis was investigated. We also investigated the optimal value for PreAP using several empirical monitoring methods, such as a pressure pillow. Our investigation indicated that PreAP is a critical factor in the determination of delivered blood flow and hemolysis, both of which occured at pressure values more negative than ?150 mm Hg. With the exception of direct pressure monitoring, commonly used monitoring methods for PreAP were determined to be ineffective. We propose that the use of a vacuum monitor would permit regular measurement of PreAP.     

Pressure garments for use in the treatment of hypertrophic scars--a review of the problems associated with their use

Pressure garments have been the mainstay of hypertrophic scar treatment since the 1970s. However, there are many problems associated with their use. This is the first in a series of papers on pressure garments that will review the literature published to date on the origins of pressure garments for hypertrophic scar treatment and the problems associated with current pressure garment use.     

Pressure by design: How to improve the consistency of pressure garments in the clinical environment and implement a simple method for gathering evidence to establish efficacy

Pressure garments are used to treat scars after major trauma including burns. However, the ideal pressure for treatment is not known. Pressures exerted are not routinely measured and garments exert a wide range of pressures. Therefore, current treatment and its efficacy are variable.Pressure Garment Design Tools were introduced in 2012 but their application in hospitals has not been reported. A Garment Dimension and Pressure Calculator was used to audit pressures delivered by 8 pressure garments made for children using the hospital department’s standard reduction factor. The tool was easy to use and showed that pressures exerted by standard garments ranged from 15 to 54 mmHg with highest pressures exerted on wrists.Results of our pilot study indicated that the Garment Dimension and Pressure Calculator was slightly quicker to use than our normal manual process for calculating garment dimensions and enabled easy auditing of past treatment. The Pressure Garment Design Tool was easy to use and calculated garments that exerted the mean target pressures of 15 mmHg and 25 mmHg, improving consistency.Pressures exerted by garments were difficult and time consuming to measure with the Picopress sensor. Pressure was not distributed evenly around the limbs and measurements were inaccurate on the smallest limbs.     

System for intraoperative evaluation of soft-tissue-generated forces during total hip arthroplasty by measurement of the pressure distribution in artificial joints.

A system for evaluating the soft-tissue-generated forces at the hip joint was developed. The system enabled measurement of contact pressure distribution at hip joint surfaces, as well as evaluation of the artificial hip joint condition during total hip arthroplasty (THA). First, a pressure sensor module that forms part of the artificial joint was constructed. Eight small pressure sensors were installed in the spherical head component of the ball-and-socket joint. Next, software for recording and visualizing the detected pressures at 1-millisecond intervals was developed. The pressure distribution was displayed in real time via 3D computer graphics on a monitor. The system enabled intuitive recognition of the direction of soft-tissue-generated forces and pressure distribution in three dimensions. Accuracy tests were conducted using a high-accuracy 6-degree-of-freedom positioning device and digital force gauge. The error between the applied loads and measured forces was 3.42 +/- 3.26 N (mean +/- standard deviation) for each coordinate in 10 trials involving load application from 10 different directions. Next, a clinical evaluation was conducted during THA. The relative positions of the cup and stem component were measured using a surgical navigation system simultaneously with the pressure measurement. The system allowed real-time acquisition of information regarding the artificial hip joint, as well as comparison of the differences in the hip condition when several types of neck were used. Further improvements to the calibration method should enable more accurate measurements. We believe this system will be a useful tool for selecting an appropriate implant that fits a patient's hip joint or for estimating the risk of complications following surgery.     

Compression Garments and Exercise: No Influence of Pressure Applied

Compression garments on the lower limbs are increasingly popular among athletes who wish to improve performance, reduce exercise-induced discomfort, and reduce the risk of injury. However, the beneficial effects of compression garments have not been clearly established. We performed a review of the literature for prospective, randomized, controlled studies, using quantified lower limb compression in order to (1) describe the beneficial effects that have been identified with compression garments, and in which conditions; and (2) investigate whether there is a relation between the pressure applied and the reported effects. The pressure delivered were measured either in laboratory conditions on garments identical to those used in the studies, or derived from publication data. Twenty three original articles were selected for inclusion in this review. The effects of wearing compression garments during exercise are controversial, as most studies failed to demonstrate a beneficial effect on immediate or performance recovery, or on delayed onset of muscle soreness. There was a trend towards a beneficial effect of compression garments worn during recovery, with performance recovery found to be improved in the five studies in which this was investigated, and delayed-onset muscle soreness was reportedly reduced in three of these five studies. There is no apparent relation between the effects of compression garments worn during or after exercise and the pressures applied, since beneficial effects were obtained with both low and high pressures. Wearing compression garments during recovery from exercise seems to be beneficial for performance recovery and delayed-onset muscle soreness, but the factors explaining this efficacy remain to be elucidated.

Key points

• We observed no relationship between the effects of compression and the pressures applied.
• The pressure applied at the level of the lower limb by compression garments destined for use by athletes varies widely between products.
• There are conflict results regarding the effects of wearing compression garments during exercise.
• There is a trend towards a beneficial effect of compression garments worn during recovery.

Key words: Compression garment, venous return, exercise, muscle soreness, recovery, performance     

A novel technique to determine pressure in pressure garments for hypertrophic burn scars and comfort properties

Current recommendations state that pressure garments should be worn for up to 2 years for hypertrophic burn scars. Thermo-physiological properties of pressure garments were assessed by the thermo-physiological tests and a comparison of the fabric with a sportwool which is a single-jersey knitted fabric was performed. In this novel technique, it was aimed to determine the exact pressure of pressure garments on the applied body part. For the theoretical part of this study, the Laplace equation was used with an optimum pressure of 20 mmHg and a relationship between change in length versus circumference was calculated. To determine the change in length a ruler was prepared for each predetermined circumference value using this relationship. Grid printed fabric samples were prepared with an interval of 2 cm in width direction to be used for the calculation of mean pressure on a Mannequin Leg. The resultant mean pressure calculated experimentally on Mannequin Leg as 24 mmHg was compared to the optimum pressure of 20 mmHg. It was observed that the two values were not statistically significantly different.     

Pressure therapy for scars: Myth or reality? A systematic review

BackgroundHypertrophic scarring is a deviate occurrence after wound closure and is a common burn sequela. The mainstay of scar treatment consists of a trifold approach: hydration, UV-protection and the use of pressure garments with or without extra paddings or inlays to provide additional pressure. Pressure therapy has been reported to induce a state of hypoxia and to reduce the expression pattern of transforming growth factor-β1 (TGF-β1), therefore limiting the activity of fibroblasts. However, pressure therapy is said to be largely based on empirical evidence and a lot of controversy concerning the effectiveness still prevails. Many variables influencing its effectivity, such as adherence to treatment, wear time, wash frequency, number of available pressure garment sets and amount of pressure remain only partially understood. This systematic review aims to give a complete and comprehensive overview of the currently available clinical evidence of pressure therapy.MethodsA systematic search for articles concerning the use of pressure therapy in the treatment and prevention of scars was performed in 3 different databases (Pubmed, Embase, and Cochrane library) according to the PRISMA statement. Only case series, case-control studies, cohort studies, and RCTs were included. The qualitative assessment was done by 2 separate reviewers with the appropriate quality assessment tools.ResultsThe search yielded 1458 articles. After deduplication and removal of ineligible records, 1280 records were screened on title and abstract. Full text screening was done for 23 articles and ultimately 17 articles were included. Comparisons between pressure or no pressure, low vs high pressure, short vs long duration and early vs late start of treatment were investigated.ConclusionThere is sufficient evidence that indicates the value of prophylactic and curative use of pressure therapy for scar management. The evidence suggests that pressure therapy is capable of improving scar color, thickness, pain, and scar quality in general. Evidence also recommends commencing pressure therapy prior to 2 months after injury, and using a minimal pressure of 20–25 mmHg. To be effective, treatment duration should be at least 12 months and even preferably up to 18–24 months. These findings were in line with the best evidence statement by Sharp et al. (2016).     

Adherence to pressure garment therapy in adult burn patients

Pressure garment therapy (PGT) is a generally accepted procedure to prevent hypertrophic scarring after severe burns. Wearing pressure garments is uncomfortable and challenging for the patient and, consequently adherence is low. In order to improve adherence, precise knowledge about the advantages and disadvantages of PGT is necessary. In this study we investigated specific aspects which inhibit or reinforce the application of PGT on the patients’ part. Twenty-one patients participated in a semi-structured interview concerning their experiences with PGT. The complaints most frequently mentioned were ‘physical and functional limitations’ caused by the garments, ‘additional effort’ created by the need to care for garments and ‘perceived deficiencies’ of the treatment. At the same time, most of the patients reported coping strategies used to persevere with the therapy. Coping can be categorised into ‘behavioural’ and ‘cognitive coping strategies’. Besides the ‘expectation of success’, ‘emotional’ as well as ‘practical support’ and experiencing ‘good outcome’ were motivating factors for the patients. Based on the analyses of limitations and resources, recommendations for future interventions enhancing adherence are outlined.     

Measurement of bone blood flow using the hydrogen washout Technique—Part I: Quantitative evaluation of tissue perfusion in the laboratory rat

The measurement of blood flow in bone is of interest in both clinical and experimental settings. Such determinations would ideally provide accurate, quantitative, and reproducible data with relatively simple and safe technology, even in the small bones of experimental animals. Methods that provide absolute or quantitative measurements include positron emission tomography, “isotope fractioning” using radioactive or fluorescent‐labeled microspheres, and measurement of the rate of washout of diffusible tracers delivered either by injection or inhalation. In this article, we describe in detail a modification of the original Whiteside hydrogen washout technique, using modern hydrogen sensors, a micromanipulator for probe placement, and custom software that greatly simplifies blood flow determination and is effective in the small bones of experimental animals. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:741–745, 2008     

Measuring pressure under burns pressure garments using the Oxford Pressure Monitor

Pressure garments are used extensively in the treatment of hypertrophic scarring following burn injuries. The Oxford Pressure Monitor was used to measure garment-scar interface pressure (mmHg) using a number of fabric types over various body parts. The results indicate a wide range of pressure values between different garments and body parts with the greatest pressures found over the dorsum of hands and feet. The problems of achieving 'optimal pressure' over hypertrophic scarring are discussed with emphasis on the need for more accurate measuring equipment.     

Development and psychometric characteristics of the SCI-QOL Pressure Ulcers scale and short form

ObjectiveTo develop a self-reported measure of the subjective impact of pressure ulcers on health-related quality of life (HRQOL) in individuals with spinal cord injury (SCI) as part of the SCI quality of life (SCI-QOL) measurement system.DesignGrounded-theory based qualitative item development methods, large-scale item calibration testing, confirmatory factor analysis (CFA), and item response theory-based psychometric analysis.SettingFive SCI Model System centers and one Department of Veterans Affairs medical center in the United States.ParticipantsAdults with traumatic SCI.Results189 individuals with traumatic SCI who experienced a pressure ulcer within the past 7 days completed 30 items related to pressure ulcers. CFA confirmed a unidimensional pool of items. IRT analyses were conducted. A constrained Graded Response Model with a constant slope parameter was used to estimate item thresholds for the 12 retained items.ConclusionsThe 12-item SCI-QOL Pressure Ulcers scale is unique in that it is specifically targeted to individuals with spinal cord injury and at every stage of development has included input from individuals with SCI. Furthermore, use of CFA and IRT methods provide flexibility and precision of measurement. The scale may be administered in its entirety or as a 7-item “short form” and is available for both research and clinical practice.     

Validation of the Pliance X System in measuring interface pressure generated by pressure garment

Introduction

Pressure monitoring is crucial for effective pressure therapy. Precise and reliable interface pressure measurement system, however, remains unavailable in current practice.

Methodology

This is a validation study on the application of a recently developed device, the Pliance X System, for static interface pressure measurement. Sensor properties were evaluated through series of laboratory tests in the first phase of the study. Phase II was a clinical study using the Pliance X system to differentiate the loading generated on the patients’ scars through additional inserts and pressure garment.

Results

Results showed high test–retest and inter-rater reliability (ICC ≥ 0.995) with good linearity (adjusted R-square = 0.997) by measuring standard weights. The maximum deviation between the measurement generated by the sensor and the sphygmomanometer cuff was ±1.451 mmHg. Results in the clinical trial revealed its discriminant ability in distinguishing different levels of pressure loading on patients with scars (p < 0.01).

Conclusion

The commercially available pressure measurement system was found to be a reliable tool for measurement of low interface pressure under static condition.     

Effect of different pressure magnitudes on hypertrophic scar in a Chinese population

Introduction

This study aimed to investigate the effect of different pressure magnitudes on treatment outcomes of hypertrophic scars, and determine pressure loss over time.

Methods

A randomized clinical trial was adopted. 53 hypertrophic scar samples from 17 Chinese participants were recruited and randomly assigned into a high pressure group (20–25 mmHg) and low pressure group (10–15 mmHg) for a five-month intervention program. The scars were assessed objectively before intervention and monthly after intervention for thickness, color (redness, yellowness and lightness) and scar pliability. Pressure magnitude at each assessment was also measured. Two-way repeated ANOVA was used to compare for differences between groups.

Results

The results showed that both levels of pressure produced reduction in scar thickness and redness, but the improvement in the high pressure group was statistically better than that of the counterpart (both p < 0.05). Monthly pressure measurement revealed that pressure loss in the high pressure group was more severe. However, no major changes in other color parameters and pliability were observed for both the groups.

Conclusion

High pressure was demonstrated to be more effective for scar management, but it was also more prone to higher pressure loss. Pressure therapy integrated with regular monitoring of the interface pressure is suggested to improve its therapeutic efficacy.     

Survey of national and local practice of compression therapy timing for burn patients in the United States

ObjectiveCompression therapy (CT) has been an important, but debated, treatment for burn scars. To better understand one source of variation in observed outcomes after CT, an evaluation of CT timing of application is needed.Materials and MethodsFollowing IRB approval, 126 burn centers were contacted to complete a 17-question survey regarding the center’s practice pattern for compression garment therapy. Locally, study subjects were identified between March 1, 2014 and December 31, 2015 and medical records examined for timing of garment ordering, delivery and fitting.ResultsThe majority believed that compression therapy is beneficial. Most centers reported using custom-fit and pre-fabricated garments, and a goal time of application between 2–4 weeks (42%) and 4–6 weeks (36%). After the garments are ordered, 61% of centers estimate that it takes 2–4 weeks for them to arrive. No significant differences in practices were found among centers treating pediatric patients only, adults only or both. Locally, the mean number of weeks between the date of original injury and garment order placement was 9.1 weeks with an additional 8.7 weeks between the date of order and date of delivery.ConclusionsThe current study identified that although the national reporting of time to garment application is estimated to be between 2–6 weeks at the majority of burn centers including our own, we found our center to be well in excess of 17 weeks. The findings offer an opportunity for local improvement, and raise the possibility of similar incongruity between goals and practice at other centers.     

【特刊综述】睾酮和雌二醇检测方法面临的挑战和取得的进展

在患者护理、公共卫生、科学研究过程中类固醇激素的检测方法需要正确而精准,因为这些检测的标准可以保证所有的临床机构和研究机构的结果具有可比性。本文陈述了目前有关检验结果易变的主要问题以及最近美国疾病预防控制中心（CDc）针对提升检验效果所做的工作。目前,睾酮和雌二醇的检测方法还无法达到高度的正确性和精准性。虽然类固醇激素检测方法已经有了长足的进步,但是实验室内部和实验室之间的检测差异仍然未能得到相应的改善。检测标准和特异性的差异被认为是测量精度变异性的来源。最终认为,类固醇激素检测的不准确性似乎是由综合因素造成的,其中不一致的检验标准和缺乏特异性被认为是产生结果变异的两个主要因素。目前,同一批次内的化验结果也变异较大,特别是在样本浓度低的情况下。2007至2011年间的质谱分析法和CDC参考方法之间的平均绝对偏差下降了50％,由此可以看出CDC激素标准化测试程序正在提高临床化验的准确性。这种测试程序可以为CDC参考方法提供追朔源头的途径,从而减少产生测量结果变异的因素。