Lisa Macintyre

The study of pressure delivery for hypertrophic scar treatment

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 occupational therapists. However, no clear scientifically established method has ever been published for their manufacture from powernet fabrics. The earlier work identified the most commonly used fabrics and construction methods for the production of pressure garments by occupational therapists in UK burn units. These methods have now been evaluated by measuring the pressures delivered to both cylinder models and to human limbs using I‐scan® pressure sensors. The effect of cylinder/limb circumference and the effects of the fabric and reduction factor used in pressure garment construction on pressures exerted have now been established. These measurements confirm the limitations of current pressure garment construction methods used in UK hospitals. These results were also used to evaluate the Laplace law for the prediction of interface pressures.

The impact of design variables and aftercare regime on the long-term performance of pressure garments.

We sought to establish the impact of pressure garment design variables, moisturizer use, and laundry method on the ability of pressure garments to maintain their pressure delivering potential, indicated here by garment tension, over time and use. Twenty-six sets of three replicate pressure garment sleeves were constructed from four powernet fabrics, using three reduction factors and six sleeve dimensions. These pressure garment sleeves were extended for 23 hours on static cylinder models followed by hand or machine laundry up to 28 times. Some sleeves were additionally exposed to moisturizers during their extension. Garment tension and dimensions were measured before and during the simulated wear and wash period to indicate each garment’s ability to maintain its tension and therefore pressure throughout a period of “use.” The results of the investigation were analyzed in groups where each group contained only 1 variable, thereby allowing the variables with the most significant impact on tension degradation to be identified. The investigation confirmed that all pressure garments lost tension and therefore pressure delivering ability over time and use. It further revealed that pressure garments designed to exert greater pressures degraded faster than those designed to exert lower pressures. Contact between pressure garments and moisturizers accelerated tension degradation, and machine-washing pressure garments tended to prolong their pressure-delivering properties compared with hand-washing them. To maintain the initial pressure delivered by pressure garments, powernet fabrics should be prestressed before being designed/constructed and they should be machine-washed by patients.

New calibration method for I-scan sensors to enable the precise measurement of pressures delivered by 'pressure garments'

Accurate measurement of the pressure delivered by medical compression products is highly desirable both in monitoring treatment and in developing new pressure inducing garments or products. There are several complications in measuring pressure at the garment/body interface and at present no ideal pressure measurement tool exists for this purpose. This paper summarises a thorough evaluation of the accuracy and reproducibility of measurements taken following both of Tekscan Inc.s recommended calibration procedures for I-scan sensors; and presents an improved method for calibrating and using I-scan pressure sensors. The proposed calibration method enables accurate (±2.1 mmHg) measurement of pressures delivered by pressure garments to body parts with a circumference ≥30 cm. This method is too cumbersome for routine clinical use but is very useful, accurate and reproducible for product development or clinical evaluation purposes.

Design, Manufacture and Testing of Capacitive Pressure Sensors for Low-Pressure Measurement Ranges

This article presents the design, manufacture and testing of a capacitive pressure sensor with a high, tunable performance to low compressive loads (<10 kPa) and a resolution of less than 0.5 kPa. Such a performance is required for the monitoring of treatment efficacy delivered by compression garments to treat or prevent medical conditions such as deep vein thrombosis, leg ulcers, varicose veins or hypertrophic scars. Current commercial sensors used in such medical applications have been found to be either impractical, costly or of insufficient resolution. A microstructured elastomer film of a polydimethylsiloxane (PDMS) blend with a tunable Young’s modulus was used as the force-sensing dielectric medium. The resulting 18 mm × 18 mm parallel-plate capacitive pressure sensor was characterised in the range of 0.8 to 6.5 kPa. The microstructuring of the surface morphology of the elastomer film combined with the tuning of the Young’s modulus of the PDMS blend is demonstrated to enhance the sensor performance achieving a 0.25 kPa pressure resolution and a 10 pF capacitive change under 6.5 kPa compressive load. The resulting sensor holds good potential for the targeted medical application.

The Study of Pressure Delivery for Hypertrophic Scar Treatment

Pressure garments made from elastic fabrics are commonly used to treat hypertrophic scars. Occupational Therapists in the UK hospitals do not commonly take into account the potential influence of either fabric properties or the body part circumference on the pressures exerted by pressure garments constructed with standard reduction factors. This investigation sought to establish the relationship between the pressures exerted on cylinder models by pressure garments (made from 4 different powernet fabrics) and the circumference of the cylinder model.

Nanocomposite-Based Microstructured Piezoresistive Pressure Sensors for Low-Pressure Measurement Range

Piezoresistive pressure sensors capable of detecting ranges of low compressive stresses have been successfully fabricated and characterised. The 5.5 × 5 × 1.6 mm3 sensors consist of a planar aluminium top electrode and a microstructured bottom electrode containing a two-by-two array of truncated pyramids with a piezoresistive composite layer sandwiched in-between. The responses of two different piezocomposite materials, a Multiwalled Carbon Nanotube (MWCNT)-elastomer composite and a Quantum Tunneling Composite (QTC), have been characterised as a function of applied pressure and effective contact area. The MWCNT piezoresistive composite-based sensor was able to detect pressures as low as 200 kPa. The QTC-based sensor was capable of detecting pressures as low as 50 kPa depending on the contact area of the bottom electrode. Such sensors could find useful applications requiring the detection of small compressive loads such as those encountered in haptic sensing or robotics.

Impact of Moisture on the Pressure Delivering Potential of Pressure Garments.

Pressure garments are the main method of treatment and prophylaxis for hypertrophic burn scars. The pressure they exert on the scarred skin prevents contractures forming, reduces the itchiness and pruritus associated with active hypertrophic scars, and is believed, by many, to hasten normalization of the scar tissue. The pressure exerted is believed to be critical to treatment success and can be predicted based on laboratory measurement of the fabric’s tension profile. All previous research on the pressures delivered by pressure garments has been undertaken using dry fabrics in either laboratory or clinical conditions. However, many patients have complained of increased perspiration when wearing pressure garments, and many burn victims live and work in hot conditions where high levels of perspiration may be expected. This article investigated the impact of moisture content on fabric tension and thus the pressure exerting ability of pressure garments. Four different fabrics currently used in the construction of pressure garments were evaluated in seven different states of “wetness” from completely dry to completely saturated in water or artificial perspiration. Standard laboratory methods were used to measure the initial tension in fabrics and the tension after 11 cycles of extension. Pressures that would be exerted by these fabrics were calculated using the Laplace law. The results of this study showed that the tension, and therefore pressure delivering ability, of fabrics used in pressure garments was significantly reduced when they were wet but that the amount or type of “wetness” did not have a significant effect on pressure delivering ability.

Anti-embolism stockings, the similarities and differences

Abstract The medical textiles sector is growing annually, estimated to reach

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

2.7 billion by 2018. Predominantly attributed to the growing and ageing population, and consequently there has been a vast increase in venous disorders. Currently 61% of the British population are thought to be at risk of deep vein thrombosis (DVT), of which the majority is avoidable given the correct prophylaxis. Anti-embolism stockings (AES) are used to prevent DVT when hospitalised patients are supine for long periods of time. The market place is competitive, with numerous brands striving to win the local British National Health Service contract. It is a commodity market, with low profit margins but high volumes. The aim of this research was to seek an understanding of the AES on the market, exploring the different construction techniques, knit notations and yarn characteristics in three popular AES brands, with the overall aim of providing a basis of knowledge to improve product development, product efficacy and ultimately save lives.