Instruction of compression therapy by means of interface pressure measurement

Pressure-Measuring Devices for Compression Therapy in Venous Leg Ulcers: A Comprehensive Review

OBJECTIVE

To investigate the evolution of pressure-measuring devices used in compression treatment for venous leg ulcers and assess the most practical and effective devices to determine optimal pressure in compression therapy.

DATA SOURCES

Relevant information was retrieved from databases including Google Scholar, PubMed, Wiley Online, and ScienceDirect without publication date restrictions. The keywords included venous leg ulcer, compression therapy, pressure measuring device, pressure sensor, and wireless system.

STUDY SELECTION

Studies included in the review had to be published in English and discuss or compare pressure-measuring devices/sensors for compression therapy, the development of alternative sensors, and the applications of wireless technologies. Veterinary studies, conference proceedings, and unpublished articles were excluded. Applicable studies and articles were critically evaluated and synthesized.

DATA EXTRACTION

After abstract review, 39 studies were identified. During full-text review, study details were collected using a data extraction form and organized into tables. Device attributes, accuracy, price, and limitations were categorized and analyzed.

DATA SYNTHESIS

Studies disagree on the effectiveness and user-friendliness of existing pressure-measuring devices. These devices often impact user comfort and convenience, which are crucial factors in the adoption and use of wearable devices. Potential solutions for pressure-measuring devices with promising technologies were proposed: four feasible alternative sensors are described that could improve comfort and facilitate prolonged use under bandages. Advanced communication technologies may provide more convenience for users and practitioners.

CONCLUSIONS

Conventional pressure-measuring devices used in compression therapy are not designed for the user's comfort and convenience. The use of flexible and stretchy pressure sensors (e-skin) provides good biocompatibility, conformability, and comfort and when integrated with near-field communication technology could address the drawbacks of current pressure-measuring devices.

Thin-Film Flexible Wireless Pressure Sensor for Continuous Pressure Monitoring in Medical Applications

Physiological pressure measurement is one of the most common applications of sensors in healthcare. Particularly, continuous pressure monitoring provides key information for early diagnosis, patient-specific treatment, and preventive healthcare. This paper presents a thin-film flexible wireless pressure sensor for continuous pressure measurement in a wide range of medical applications but mainly focused on interface pressure monitoring during compression therapy to treat venous insufficiency. The sensor is based on a pressure-dependent capacitor (C) and printed inductive coil (L) that form an inductor-capacitor (LC) resonant circuit. A matched reader coil provides an excellent coupling at the fundamental resonance frequency of the sensor. Considering varying requirements of venous ulceration, two versions of the sensor, with different sizes, were finalized after design parameter optimization and fabricated using a cost-effective and simple etching method. A test setup consisting of a glass pressure chamber and a vacuum pump was developed to test and characterize the response of the sensors. Both sensors were tested for a narrow range (0–100 mmHg) and a wide range (0–300 mmHg) to cover most of the physiological pressure measurement applications. Both sensors showed good linearity with high sensitivity in the lower pressure range <100 mmHg, providing a wireless monitoring platform for compression therapy in venous ulceration.

Interface pressure changes under compression bandages during period of wearing

BACKGROUND

The aim of the present study was to investigate the changes in pressure over time under three different compression bandages and compare the temporal patterns of pressure changes among them.

METHODS

The 4-hour changes in interface pressure were investigated in 10 volunteers with no venous disease or leg swelling. In 20 patients with venous ulcers, the change in interface pressure was measured after 4 hours, 1 day, and 7 days of bandage wearing. The three bandages tested were the Smart Sleeve compression system (SSB; Carolon, Rural Hall, NC), Coban 2 (C2; 3M, St Paul, Minn), and Profore Lite (PL; Smith & Nephew, London, United Kingdom). Pressure measurements were performed using the PicoPress transducer (Microlab, Padua, Italy) and the Juzo Pressure Monitor (Juzo, Cuyahoga Falls, Ohio).

RESULTS

In the 10 volunteers, the mean pressure loss during the first 4 hours under the SSB, C2, and PL were 4.5, 3.7, and 6.6 mm Hg, respectively. No significant differences were seen in the pressure loss among the three bandages, whether in the supine (P = .59) or standing (P = .47) position. In the 20 patients with venous ulcers, the pressure had decreased gradually over 7 days under the C2 bandages. For the SSB and PL bandages, however, the interface pressure was relatively stable during the first day but decreased significantly afterward. The mean pressure loss during the 7 days was 4.7, 7.7, and 8.6 mm Hg for the SSB, PL, and C2, respectively (P = .017). Only the SSB maintained a desirable mean pressure >30.0 mm Hg on the seventh day in the patients with venous ulcers.

CONCLUSIONS

The interface pressure had decreased over time under all three studied bandages. However, the temporal pattern of the pressure changes varied among the different bandages. Therefore, monitoring the interface pressure, allowing for adjustment or changes of the bandage at an accurate point, is essential to maintain a desirable interface pressure during compression therapy.

Textile-based compression therapy in managing chronic oedema: Complex interactions

BACKGROUND

Compression is a common therapy for management of chronic disease, including oedema of the lower limb. Modern compression interventions exert pressure on the lower limb through use of one or more materials which exert pressure against the limb over time. Where these materials are textiles, they range from elastic to inelastic, and are produced using knitting, weaving, or other textile technologies which can be manipulated to control performance properties. Thus, understanding of both the materials/textiles and the human body is needed if the most appropriate compression device and treatment strategy is to be used. Neither is independent of the other. This review aims to enhance understanding of critical textile performance properties and how selection of textiles may affect treatment efficacy when managing chronic oedema of the lower limb.

METHOD

Relevant papers for review were identified via PubMed Central® library, and Google Scholar using keywords associated with textile-based treatments of the oedematous lower limb and wider interdisciplinary factors.

RESULTS

Assessment of the disorder, the severity of oedema, and location of fluid accumulation are required to inform treatment of chronic oedema. While the need to understand the patient is well established (e.g. age, sex, body mass index, skin thickness and colour, patient compliance with treatment), information about preferred compression systems and material structures, and inherent properties of these, is generally lacking.

CONCLUSION

Greater detail about materials used (e.g. fabric structure, number and order of layers, fibre content) and patient diagnosis (e.g. underlying cause, severity, location of oedema; patient age and sex; evidence of compliance with treatment; pressure exerted; lower leg shape, size, and properties of the tissue) is needed to facilitate advances in efficacy of compression treatment. Reduced limb swelling with a textile-based treatment occurs simultaneously with changes to the textile itself. Textiles cannot be considered inert.

Thrombosis after sclerotherapy and poorly applied bandaging for venous leg ulcers: case reports

Side-effects occurring in patients treated by multilayer bandaging may be neurological, dermatological or arterial. We report on two cases of venous thrombosis involving outpatients treated for venous leg ulcers (VLU). In the first case, a lack of understanding of multilayer bandages and training on their use by the nursing staff was likely the cause of a superficial vein thrombosis (SVT) in a great saphenous vein tributary. The second case occurred in a patient suffering from an ulcer complicated by oedema. Insufficient education of the patient in alert symptoms for his condition and an inappropriate medical follow-up were the direct causes of a non-severe distal vein thrombosis. We conclude that, as it has been suggested over a number of years, patients being treated with bandage therapy must be rigorously and carefully monitored.

Controlling compression bandaging pressure in leg ulcer research trials: A summary of the literature

Compression bandaging remains the ‘gold standard’ intervention for the treatment of venous leg ulcers. Numerous studies have investigated the effect of a large variety of compression bandaging techniques and materials on venous leg ulcer healing. However, the majority of these studies failed to monitor both actual bandage application pressures and the bandaging competency of participating clinicians. A series of literature searches to explore the methods, practices, recommendations and results of monitoring compression bandaging pressures in leg ulcer research trials were undertaken. This included investigating the reliability and validity of sub-bandage pressure monitors and the degree to which compression bandaging achieves the recommended sub-bandage pressure. The literature revealed inconsistencies regarding the monitoring of sub-bandage pressure and in sub-bandage pressures produced by clinicians. This creates difficulties when comparing study outcomes and attempting to develop evidence-based practice recommendations.

Compression Garments for Medical Therapy and Sports

Compression garments are elastic clothing with an engineered compression gradient that can be worn on limbs, upper, lower, or full body to use for therapy and sports. This article presents an overview and review on the compression garments and concentrates on the design of compression garments with an appropriate pressure for specific applications. It covers the types of compression garments, fibers and yarns, knitted fabric construction, garment design, an evaluation system, and pressure measurement and modeling. The material properties, fabric properties, pressure modeling, and the garment design system presents the prediction, design, and fabrication of the compression garments. Lastly, the research status and directions are discussed.

Comfort and compressional characteristics of padding bandages

BACKGROUND

Padding bandage is an essential component of the multi-layer compression system used for chronic venous management. Padding plays a critical role in managing pressure over bony prominences and ensuring uniform pressure distribution around the limb circumference. Moreover, it helps in the management of heat, moisture and body fluids or exudates during the course of treatment to provide comfort to the patients.

OBJECTIVE

To study the effect of structural and constructional parameters on the compressional (pressure absorption or distribution) and comfort (air, moisture and heat transmission) characteristics of the padding.

METHODS

This research focuses on the examination of polypropylene based nonwoven padding samples. Critical factors, i.e., fiber linear density, needling density and mass per unit area, have been chosen for this study to find their significance on the performance of padding. Simple laboratory based methods have been proposed to examine pressure reduction and comfort characteristics of the padding.

RESULTS

Pressure absorption by the padding decreases with increase in mass per unit area and needling density of the padding. A padding composed of thicker fiber absorbs more pressure compared to padding made from thinner fiber. On examining comfort, it was found that the air and moisture vapor transmission increase with decrease in mass per unit area and needling density but have opposite effects with fiber linear density (p<0.01). The heat transmission decreases with increase in both mass per unit area and fiber linear density but has opposite effect for needling density.

CONCLUSION

Padding composed of thick fiber with low mass per unit area and needling density could be more effective in pressure management and ensuring comfort. These results could be very useful for health practitioners, fabric engineers and manufactures to understand the significance of fibrous materials and their role in compression management, and could be further used as design consideration to optimized padding performance.

Characterization of a pressure measuring system for the evaluation of medical devices

The purpose of this study is to evaluate the possible use of four “FSA” thin and flexible resistive pressure mapping systems, designed by Vista Medical (Winnipeg, Manitoba, Canada), for the measurement of interface pressure exerted by lumbar belts onto the trunk. These sensors were originally designed for the measurement of low pressure applied by medical devices on the skin. Two types of tests were performed: standard metrology tests such as linearity, hysteresis, repeatability, reproducibility and drift, and specific tests for this application such as curvature, surface condition and mapping system superposition. The linear regression coefficient is between 0.86 and 0.98; hysteresis is between 6.29% and 9.41%. Measurements are repeatable. The location, time and operator, measurement surface condition and mapping system superposition have a statistically significant influence on the results. A stable measure is verified over the period defined in the calibration procedure, but unacceptable drift is observed afterward. The measurement stays suitable on a curved surface for an applied pressure above 50 mmHg. To conclude, the sensor has acceptable linearity, hysteresis and repeatability. Calibration must be adapted to avoid drift. Moreover, when comparing different measurements with this sensor, the location, the time, the operator and the measurement surface condition should not change; the mapping system must not be superimposed.

An optical fiber Bragg grating force sensor for monitoring sub-bandage pressure during compression therapy

Graduated compression bandaging of the lower limbs is the primary therapy for venous leg ulcers with its efficacy believed to be predominantly dependent on the amount and the distribution of the compressive pressure applied. There has been on-going demand for an ideal sensor to facilitate in-vivo monitoring of the sub-bandage pressure. Several methods and devices have been reported but each has its limitations, such as bulkiness, low tolerance to movement, susceptible to thermal noise and single point sensing. An optical fiber force sensor is demonstrated, consisting of two arrays of fiber Bragg grating (FBG) entwined in a double helix form and packaged with contact-force sensitivity. This sensor array has inherent temperature immunity and is capable of real-time, distributed sensing of sub-bandage pressure. The calibration results of the sensor array, as well as the validation human trial results, are presented.

Bandage pressure measurement and training: simple interventions to improve efficacy in compression bandaging

Compression bandaging is a major cornerstone in the treatment of chronic venous insufficiency. Its efficacy considerably depends on the applied pressure and it is therefore largely dependent on the individual applying the system. The sub-bandage pressure was measured under three consecutive compression bandages applied by 21 nurses before and after training and the introduction of a pressure monitor (Kikuhime, MediTrade, Denmark). A questionnaire was used to evaluate the self-rating before and after the intervention. Before intervention, a questionnaire showed the confidence of the nurses in reaching sufficient sub-bandage pressure levels. However, 34.9% of all bandages were shown to be insufficient before intervention (< 20 or > or = 60 mmHg) and only 17.5% after intervention, representing a statistically significant improvement through intervention. Of the insufficient bandages, 77.3% were applied by nurses with more than 10 years of working experience. Furthermore, the mean sub-bandage pressure in active standing position, a marker for the working pressure, was improved form 38.7 to 64.3 mmHg after intervention. Continuous awareness and training are necessary to maintain sufficient compression bandaging. The availability of a pressure monitor was helpful to reach this goal. Long work experience and self-rating alone is not sufficient to maintain adequate quality in compression bandaging.

The influence of different sub-bandage pressure values on venous leg ulcers healing when treated with compression therapy

BACKGROUND

Venous leg ulcers (VLU) have a huge social and economic impact. An estimated 1.5% of European adults will suffer a venous ulcer at some point in their lives. Despite the widespread use of bandaging with high pressure in the treatment of this condition, recurrence rates range between 25% to 70%. Numerous studies have suggested that the compression system should provide sub-bandage pressure values in the range from 35 mm Hg to 45 mm Hg in order to achieve the best possible healing results.

METHODS

An open, randomized, prospective, single-center study was performed in order to determine the healing rates of VLU when treated with different compression systems and different sub-bandage pressure values. One hundred thirty-one patients (72 women, 59 men; mean age, 59-years-old) with VLU (ulcer surface >3 cm(2); duration >3 months) were randomized into three groups: group A - 42 patients who were treated using an open-toed, elastic, class III compression device knitted in tubular form (Tubulcus, Laboratoires Innothera, Arcueil, France); group B - 46 patients treated with the multi-component bandaging system comprised of Tubulcus and one elastic bandage (15 cm wide and 5 cm long with 200% stretch, Niva, Novi Sad, Serbia); and group C - forty-three patients treated with the multi-component bandaging system comprised of Tubulcus and two elastic bandages. Pressure measurements were taken with the Kikuhime device (TT MediTrade, Soro, Denmark) at the B1 measuring point in the supine, sitting, and standing positions under the three different compression systems.

RESULTS

The median resting values in the supine and standing positions in examined study groups were as follows: group A - 36.2 mm Hg and 43.9 mm Hg; group B - 53.9 mm Hg and 68.2 mm Hg; group C - 74.0 mm Hg and 87.4 mm Hg. The healing rate during the 26-week treatment period was 25% (13/42) in group A, 67.4% (31/46) in group B, and 74.4% (32/43) in group C. The success of compression treatment in group A was strongly associated with the small ulcer surface (<5 cm(2)) and smaller calf circumference (CC; <38 cm). On the other hand, compliance in group A was good. In groups B and C, compliance was poor in patients with small CC, but the healing rate was high, especially in patients with large ulcers and a large CC (>43 cm).

CONCLUSION

The results obtained in this study indicate that better healing results are achieved with two or multi-component compression systems than with single-component compression systems and that a compression system should be individually determined for each patient according to individual characteristics of the leg and CC. Target sub-bandage pressure value (B1 measuring point in the sitting position) of the compression system needed for the ulcer healing could be determined according to a simple formula, CC + CC/2.

An overview of technologies related to care for venous leg ulcers

Venous leg ulcers remain a major problem in the United States, with spending reaching more than $1 billion annually. Current treatment options for this condition center around the use of compression therapy delivered by bandages, medical-grade stockings, or pneumatic compression devices. While these forms of therapy can produce dramatic improvements, cost and patient compliance remain an issue. In parallel with this need, wearable, wireless health monitoring systems have recently emerged as a low-cost solution for management of chronic health conditions. To this end, researchers at the Center for Robotics and Intelligent Machines (North Carolina State University) and the Carolon Company (Rural Hall, NC) have proposed an integrated sensing and therapeutic compression module. This article will review technologies related to the design of such a device, as well as provide direction for future research.

Intermittent pneumatic compression in immobile patients

The purpose of this study is to stress the value of using intermittent pneumatic compression (IPC) in immobile patients. The use of IPC helps prevent limb oedema and the associated skin changes frequently seen on the legs of the immobile patient. Oedema formation is caused by an increase of fluid extravasation, while skin changes including leg ulcers are mainly because of a deficiency of the venous and lymphatic pumps. Conventional compression stockings and bandages impede leg swelling but are less efficient in supporting the deficient veno-lymphatic pump when patients are unable to move. In this situation, actively compressing the limb using IPC is a very meaningful and effective treatment option. Because of a lack of literature on the specific indication of IPC in immobile patients, experimental studies and randomised controlled trials in similar situations are reviewed. IPC is a very effective although underused treatment modality, especially in immobile, wheelchair-bound patients. By inflation and deflation of the air-filled garments, IPC produces cycles of pressure waves on the leg, thus mimicking the working and resting pressures applied by compression bandages. IPC not only reduces leg swelling but also augments the veno-lymphatic pump, which is essential for the restoration of the damaged microcirculation of the skin.

Variability of pressure provided by sustained compression

Compression therapy is the cornerstone of treatment for patients with venous leg ulcers (VLUs). Although it is generally accepted that the therapeutic outcomes are directly related to the quality of compression therapy, delivering precise and sustained compression therapy is an ongoing challenge for health care professionals. Several factors influence quality of compression therapy: physical structure and elastomeric properties of the compression system, size and shape of the leg, skill and technique of the bandager and physical activity undertaken by the patient. Graduated compression is achieved by applying a bandage at the same tension from ankle to knee, providing the shape of the leg is normal. Many patients with VLUs have distorted legs, challenging the delivery of a desired pressure gradient. Poor bandaging technique can result in little or no benefit or may deliver too high a pressure causing a detrimental effect to the wearer. If the wearer is unable to tolerate the compression, patient concordance and effectiveness are affected. Training has been shown to reduce variability of sub-bandage pressure. Sub-bandage pressure increases during standing and walking. These pressure changes are related to the elastomeric properties of the compression systems. Health care professionals need to understand the properties of the available compression systems and how their application technique must be adjusted.

Classification of compression bandages: practical aspects

BACKGROUND

Compression bandages appear to be simple medical devices. However, there is a lack of agreement over their classification and confusion over the use of important terms such as elastic, inelastic, and stiffness.

OBJECTIVES

The objectives were to propose terms to describe both simple and complex compression bandage systems and to offer classification based on in vivo measurements of subbandage pressure and stiffness.

METHODS

A consensus meeting of experts including members from medical professions and from companies producing compression products discussed a proposal that was sent out beforehand and agreed on by the authors after correction.

RESULTS

Pressure, layers, components, and elastic properties (P-LA-C-E) are the important characteristics of compression bandages. Based on simple in vivo measurements, pressure ranges and elastic properties of different bandage systems can be described. Descriptions of composite bandages should also report the number of layers of bandage material applied to the leg and the components that have been used to create the final bandage system.

CONCLUSION

Future descriptions of compression bandages should include the subbandage pressure range measured in the medial gaiter area, the number of layers, and a specification of the bandage components and of the elastic property (stiffness) of the final bandage.

Measurement of Lower Leg Compression In Vivo: Recommendations for the Performance of Measurements of Interface Pressure and Stiffness

BACKGROUND

Interface pressure and stiffness characterizing the elastic properties of the material are the parameters determining the dosage of compression treatment and should therefore be measured in future clinical trials.

OBJECTIVE

To provide some recommendations regarding the use of suitable methods for this indication.

METHOD

This article was formulated based on the results of an international consensus meeting between a group of medical experts and representatives from the industry held in January 2005 in Vienna, Austria.

RESULTS

Proposals are made concerning methods for measuring the interface pressure and for assessing the stiffness of a compression device in an individual patient.

CONCLUSIONS

In vivo measurement of interface pressure is encouraged when clinical and experimental outcomes of compression treatment are to be evaluated.

Measuring sub-bandage pressure: comparing the use of pressure monitors and pulse oximeters

OBJECTIVE

To test the use of low-cost sub-bandage pressure monitors and pulse oximeters as part of a quality-control measure for graduated compression bandaging in leg ulcer clinics.

METHOD

Twenty-five healthy volunteers (mean age 40 years) providing 50 limbs were bandaged with a four-layer compression bandaging system. The ankle systolic pressure (ASP) was measured using a pulse oximeter (Nellcor NBP-40) before applying the graduated compression bandages. Interface pressure was measured by placing pressure sensors on the skin at three points (2cm above the medial malleolus; the widest part of the calf; and a point midway between them) in the supine and standing positions. The ASP was measured again with the pulse oximeter after the bandage had been applied, and the effect of the bandage on the ASP was recorded. The actual pressure created by the bandage was compared with the required pressure profile.

RESULTS

Interface pressures varied with change of position and movement. With the operator blinded to the pressure monitors while applying the bandages, the target pressure of 35-40mmHg at the ankle was achieved in only 36% of limbs ([mean +/- 95% confidence interval]; 32.3 +/- 1.6mmHg [supine]; 38.4 +/- 2.4mmHg [standing position]). With the help of the pressure monitors, the target pressure was achieved in 78% of the limbs. There was no correlation between the pressure monitors and pulse oximeter pressures, demonstrating that the pulse oximeter is not a useful tool for measuring sub-bandage pressures.

CONCLUSION

The results suggest a tool (interface pressure monitors) that is easy to operate should be available as part of quality assurance for treatment, training of care providers and education.

The Use of Pressure Change on Standing as a Surrogate Measure of the Stiffness of a Compression Bandage

OBJECTIVES

To measure interface pressure and stiffness of short-stretch and long-stretch bandages applied with variable strength. These parameters have a deciding influence on the efficacy of compression therapy in chronic venous disease.

DESIGN

Prospective experimental study.

MATERIALS AND METHODS

Compression bandages constructed of different materials were applied with light, moderate and high pressure. Interface pressure was measured over the medial aspect of leg in 12 healthy individuals. Long-stretch bandages were compared to short-stretch bandages. The difference between standing and supine pressure was used to characterise stiffness.

RESULTS

In the low pressure range the median pressure of the final bandage in the supine position was between 18 and 30 mmHg for the long-stretch and 25-33.5 mmHg for the short-stretch bandages (p<0.01, Mann-Whitney U-test). The median differences between standing and supine pressure were between 2.0 and 8.5 for the long-stretch and 6.0-10.5 mmHg for the short-stretch material. In the group of moderate pressure the median values in the supine position were in a range 33.0-58.0 mmHg, for long-stretch and 39.0-49.5 mmHg for short-stretch bandages, with an increase after standing of 6.0-7.0 mmHg with long-stretch, and 14.0-21.0 mmHg with short-stretch bandages (p<0.01, Mann-Whitney U-test). The median supine pressure values in the high pressure group were between 52.0 and 67.0 mmHg for long-stretch and 59.5-67.0 mmHg for short-stretch material. The median increase during standing ranged between 8.5 and 14.5 mmHg in the elastic group and 23.0-33.0 in the inelastic group (p<0.01, Mann-Whitney U-test).

CONCLUSION

A bandage applied with light pressure corresponds to the moderate pressure category of stockings. The difference between the sub-bandage pressure from supine to standing can be used to characterise the stiffness of a bandage.

How effective is training in compression bandaging techniques?

The aim of this review was to investigate whether formalized compression bandage training is required for nurses to achieve compression bandaging of high quality, that is bandaging which produces sustained graduation from toe to knee. Medline, CINAHL and Embase databases were used in the search. Randomized controlled trials and quasi-experimental trials were included where (at a minimum) nurses experienced in compression bandaging had their skills reviewed before and after training, and then reviewed once more at a later follow-up session. Three studies matched these criteria. In all three, nurses in general did not achieve sustained graduated compression before training, despite being defined as experienced bandagers. There was a substantial improvement in bandaging skills immediately following training. Two trials found that this improvement was sustained for between 2 and 4 weeks. The results of the third study suggested that improvements might not be sustained in the longer term. This review raises issues for further research including the current standard of compression bandaging, by those individuals who consider themselves competent in this skill. In addition, there needs to be argument on how nurses' bandaging skills can be improved and maintained, including the depth of role of feedback. In the meantime, nurses need to be as diligent as possible in maintenance of their compression bandaging skills, and the training they give junior staff. The effectiveness of current training cannot be assessed by short-term improvements and must not be assumed.