Novel Multimodal Sensing Systems for Wearable Knee Health Assessment

Wearable technologies for healthcare represent a popular research area, as they can provide quantitative metrics during rehabilitation, enable long-term, at-home monitoring of chronic conditions, and facilitate preventative—versus reactive—medical interventions. Moreover, their low cost makes them accessible to broad subject populations and enables more frequent measures of biomarkers. Such technologies are particularly useful for areas of medicine where the diagnostic or evaluation tools are expensive, not readily available, or time consuming. Orthopedics, in particular joint health assessment, is an area where wearable devices may provide clinicians and patients with more readily available quantitative data. The objective of this research is to investigate wearable, multimodal sensing technologies to facilitate joint health and rehabilitation monitoring, ultimately providing a “joint health score” based on evaluation of joint acoustics, electrical bioimpedance, inertial measures, and temperature data. This joint health score may be employed in various applications—including during rehabilitation after an acute injury and management of joint diseases, such as arthritis—providing an actionable metric for physicians based on the underlying physiological changes of the joint itself. This work specifically investigates the hardware for such a system. First, we examined microphones suited for wearable applications (e.g., miniature, inexpensive) that still provide robust measurements in terms of signal quality and consistency for repeated measurements. Second, we implemented a microcontroller-based system to sample high-throughput audio data as well as lower-rate electrical bioimpedance, inertial, and temperature data, which was incorporated into a fully untethered “brace.” Importantly, this work provides the fundamental hardware system for wearable knee joint health assessment.Ph.D

A NOVEL MULTI-MODAL, WEARABLE SENSING SYSTEM TO AUTOMATICALLY QUANTIFY CHANGES IN EXTRAVASCULAR FLUID LEVELS

The buildup of static edematous fluids (swelling) in the tissue is indicative of a serious medical condition that can lead to long-term tissue damage, reduction in mobility and in some cases loss of limb. This swelling can be due to internal factors such as an immunoresponse to injuries or infections, or external factors such as a leakage of infused intravenous medication to the surrounding tissue (i.e., IV infiltration or extravasation). Detecting and tracking changes in a tissue’s extracellular fluid content is crucial in diagnosing the severity of the injury and/or infection, and thereby preventing irreversible tissue damage. However, current methods for quantifying fluid levels in the extravascular space are either (1) manual and subjective, relying heavily on the medical staff’s expertise, or (2) costly and timely, such as X-rays or magnetic resonance imaging (MRI). In this dissertation, I present non-invasive wearable technologies that utilize localized bioimpedance contextualized by the tissue’s kinematics to robustly quantify changes in the biological tissue’s extracellular fluid content. Towards this goal, several robust and miniaturized systems are designed and implemented by researching different integrated circuits, analog front ends, and novel physiology-driven calibration techniques that together increase the system’s accuracy and reduce its size and power consumption. Next, novel methods and algorithms are developed to allow for unobtrusive real-time detection of changes in extracellular fluid content. The systems, methods and algorithms were validated in human subjects studies, animal models and cadaver models for ankle edema tracking, and in human subjects studies and animal tissue for intravenous infiltration detection.Ph.D

Proactive Management of Acute Oedema Following Hand and Minor Burn Injury

Burn injury is a unique trauma. The inflammatory process initiated with burn injury adversely influences all of the Starling equation variables, resulting in increased transvascular fluid filtration, so that oedema as a product of burn injury is more readily formed than in other forms of trauma. Localised wound oedema forms due to minor burn injury, with increasing systemic oedema associated with increased size of burn. It is now recognised that a marked inflammatory and immune response is created with non-severe burn injury, indicating a systemic component with all burns. The effect of oedema formation on the course of the burn healing is well described in the literature, due to its impact on the zone of stasis in the wound and its potential to result in progressive tissue loss or conversion if poorly managed. Burn conversion leads to an increase in the area and depth of the burn wound, necessitating surgical intervention, which increases the risk of scarring. Burn scarring may lead to altered function and poor aesthetic outcomes, which have the potential to adversely affect patient psychological well-being. Despite the influence of oedema on the healing of the burn wound and therefore the scar worn for life, there is little evidence to guide clinicians who aim to proactively manage this oedema, with only two published, controlled trials investigating methods to improve peripheral oedema in burn injury. The aim of the series of studies described in this thesis is to provide a holistic approach to the management of oedema following acute burn injury. To be able to effectively treat oedema, the clinician needs to be able to accurately assess the affected limb and wound for oedema. Oedema management in burn injury is often based on the clinicians’ preference of intervention, without good understanding of the optimal parameters of application or efficacy. Therefore, evidence is required for optimising the management of oedema in the acute burn injured patient. Furthermore, the hand’s unique anatomical structure that produces functional dexterity adds complexity to the assessment and management of oedema formation in the hand. Burn injury to the hand is common, as hands provide interaction with the world, and are generally vulnerable during activities of daily living. In the event of major accidents, the hands are reflexively used to protect the face and body, further predisposing them to significant injury. The ability to accurately measure oedema guides clinicians in their treatment of acute burn wound oedema. Current objective measures of oedema often lack sensitivity, increase pain, introduce a risk of infection from equipment contact with open wounds, or are cumbersome for repeated use in the clinical environment. They are also influenced by the cooperation of the patient, and burn injury often results in significant pain, impaired movement, and may require the use of medications that modify behaviour. As a result, oedema is usually assessed visually or through palpation of the tissue, noting the loss of skin creases or pitting of soft tissue. These assessments are subjective based on the clinician’s experience and do not provide objective measures that can be repeated between testers or between sessions. Demonstrating the effectiveness of proactive oedema management following acute burn injury is therefore dependent on the ability to accurately assess the oedema using a valid, reliable and sensitive objective measure. There is a lack of high-quality prospective studies investigating oedema management techniques in burn injury populations. In a 2011 systematic review, there was only one published randomised control trial, which investigated the use of electrical stimulation in addition to standard interventions for managing hand burn oedema, while a second conference presentation was reported as part of the review. There have been no further published studies in this space, providing clinicians with little guidance as to the optimal parameters to manage oedema in this challenging injury cohort. Measuring oedema in this patient group is similarly challenging. The study series in this thesis addresses the challenge of measuring hand burn oedema and wound healing. Bioimpedance spectroscopy (BIS) is a technology that has demonstrated reliability and validity for measuring whole body and limb oedema in burns patients during fluid resuscitation, and is sufficiently sensitive to measure oedema change with wound healing. Another BIS variable, Phase Angle, is validated to be a measure of cell health, as it measures the flow of current across the cell with respect to the voltage. Increased lag in the current is the result of increased cell mass and cell wall integrity (a healthier cell), resulting in an increased Phase Angle. This has been demonstrated to increase with healing in chronic wound populations, but has not been validated in acute burn injury. The first study in this thesis is a method validation study, investigating the measurement of hand volumes using a novel application of BIS. A technique to measure hand volumes using BIS has been described previously, however the burn injured hand is compromised by wounds. The guidelines for the use of BIS require that electrodes are placed on intact skin. The study compared different electrode configurations on the hand and arm to the previously described configuration in a non-injured population, to determine if different electrode configurations are valid for measuring hand volumes. The key findings of this study were that, when compared to previously described electrode positions on the dorsum of the hand and forearm, alternative electrode combinations on the volar surface of the hand and forearm, and an electrode array on the palm of the hand and the dorsum of the forearm, were both valid for measuring hand oedema volumes in an uninjured population. These outcomes provide novel evidence to guide electrode placements to measure hand volume using BIS where wounds precluded the use of standard electrode arrays. The second study in this series is a validation study, informed by and used the electrode positions assessed in the first study, to determine the validity and reliability of BIS for measuring hand (oedema) volumes in a burn injured population. Repeated hand volume measures were obtained in 100 patients presenting with hand burn injury with BIS, and with water displacement volumetry as a gold standard comparison. The results of this study demonstrated that the electrode positions assessed as valid for measuring hand volumes in an uninjured population in the first study, were valid, reliable and sensitive for measuring oedema in the hand following burn injury, showing high correlation with the gold standard comparator. This technique was used to assess the primary outcome – oedema volume change – in the third study of this series. The following studies in this thesis are intervention research, investigating techniques designed to proactively manage oedema in acute burn injury. The third study described in this thesis is the first randomised controlled trial to investigate different methods of applying compression to the hand to manage acute burn oedema. Compression is a commonly used technique to control oedema, reported to be applied based on clinician preference, which is dependent on the way each clinician was taught. In this study, 100 patients (the largest of its kind to the best of my knowledge), presenting with burn injury involving a portion of the hand were randomised to receive one of three commonly used methods of applying compression, to provide evidence as to which is the most effective at controlling acute burn wound oedema in the hand. In this study, the two most common methods of fabricating a custom compression glove using cohesive bandage were shown to be both equally effective at reducing post burn oedema in the hand, and both were more effective for reducing hand burn oedema than the control condition being an off the shelf compression glove. The patients in this study were also provided education regarding exercise to maintain function and promote oedema reduction, oedema management advice including elevation of the hand above the level of the heart at rest, and ensuring normal use of the hand while respecting the wound environment to minimise the risk of infection. These interventions resulted in significantly greater hand range of movement between test sessions, and a significant improvement in the QuickDASH (Disability of Arm, Shoulder and Hand) patient reported outcome measure. The effect of a low energy, long duration electrical stimulation on the acute burn wound was investigated in study four. Electrical stimulation has been demonstrated to improve the rate of healing of chronic wounds, and aid the reduction of oedema in a number of populations, including patients with hand burn injury when used in addition to standard physiotherapy. The novel application of electrical stimulation in this study utilised a small patient applied stimulation device for more than 20 hours per day for a period of up to 14 days, with the current applied across the wound with electrodes placed either side of the injured tissue on intact skin. This was designed as a within-patient control, randomised trial. Patients with similar size and similar depth burns to multiple limbs participated in this study. Electrical stimulation was applied to one wound, with the contralateral wound serving as the control wound. The outcomes investigated were change in oedema, as measured by the BIS variable R0, measuring the impedance of the extra-cellular fluid; and wound healing, measured by the BIS variable Phase Angle, and compared to clinical photography of the wounds, which were assessed by a consultant burns surgeon to determine wound re-epithelialisation, or healing. Phase Angle and wound impedance were demonstrated to be associated with wound healing. Electrical stimulation applied to a minor burn was shown to increase the rate of oedema reduction in the wound compared to the control wound, and increased Phase Angle at a faster rate than in the control wound, indicating an increase in cell and tissue health. This thesis presents a study series whereby the first two studies validated a new method of measuring hand burn oedema quickly, with minimal imposition on the patient. This method was demonstrated as viable and applicable in acute burn patients, in both research and clinical practice contexts, and informed the ensuing studies in this series. The final two studies presented in this thesis are randomised controlled trials investigating the proactive management of oedema in acute burn injury, and contribute significant new knowledge to the literature, providing guidance to the burn clinician who manages acute oedema to prevent conversion of the burn wound and deterioration in function. When presented with a hand burn injury, the clinician will be able to appropriately manage the ensuing oedema with a custom compression glove fabricated using a cohesive bandage with either of the most common methods therapists are taught. In addition, in minor burn wounds, the use of a small, easy to use, low energy long duration electrical stimulation device as an adjunct to standard burn wound care, will increase oedema reduction and improve the rate of wound healing compared to standard wound care alone

Smart Bioimpedance Spectroscopy Device for Body Composition Estimation

The purpose of this work is to describe a first approach to a smart bioimpedance spectroscopy device for its application to the estimation of body composition. The proposed device is capable of carrying out bioimpedance measurements in multiple configurable frequencies, processing the data to obtain the modulus and the bioimpedance phase in each of the frequencies, and transmitting the processed information wirelessly. Another novelty of this work is a new algorithm for the identification of Cole model parameters, which is the basis of body composition estimation through bioimpedance spectroscopy analysis. Against other proposals, the main advantages of the proposed method are its robustness against parasitic effects by employing an extended version of Cole model with phase delay and three dispersions, its simplicity and low computational load. The results obtained in a validation study with respiratory patients show the accuracy and feasibility of the proposed technology for bioimpedance measurements. The precision and validity of the algorithm was also proven in a validation study with peritoneal dialysis patients. The proposed method was the most accurate compared with other existing algorithms. Moreover, in those cases affected by parasitic effects the proposed algorithm provided better approximations to the bioimpedance values than a reference device.Ministerio de Economía y Competitividad (Instituto de Salud Carlos III) PI15/00306Junta de Andalucía PIN-0394-2017Unión Europea "FRAIL

Hardware design of a portable medical device to measure the quadriceps muscle group after a total knee arthroplasty by EMG, LBIA and clinical score methods

El propòsit d'aquest projecte és el disseny del hardware d'un dispositiu mèdic portàtil per a mesurar senyals d'electromiografia (EMG) i bioimpedància localitzada (LBIA), que s'utilitzarà per avaluar la progressió de dues pròtesis de genoll (Medial-Pivot i Ultra- Congruent) en pacients operats d'una artroplàstia total de genoll per a l'hospital Germans Trias i Pujol de Badalona. Per això, s'ha realitzat un estudi complet sobre els senyals d'EMG i LBIA, per tal de definir les característiques necessàries de l'equip mèdic i poder optimitzar el disseny electrònic. Per l'adquisició de senyals EMG, s'ha dissenyat i simulat un sistema compost per diferents fases, que treballen independentment per adquirir, amplificar, filtrar i adaptar el senyal EMG pel seu futur processament digital. D'altra banda, per obtenir valors de la bioimpedància localitzada dels diferents músculs que conformen el quàdriceps, s'ha dissenyat un sistema compost per dos grans blocs; el primer bloc és l'etapa d'injecció, on es genera i s'injecta un senyal feble de corrent altern a la zona a mesurar, mentre que el segon bloc, és l'etapa d'adquisició de senyals. Aquest últim s'encarrega d'adquirir la diferència de voltatge produïda per la injecció de corrent al múscul (anteriorment mencionat) per després calcular la bioimpedància a partir de la llei d'ohm. Tots els senyals són digitalitzats mitjançant el microcontrolador STM32F407VG, que s'encarregarà de processar i aconseguir les dades claus per determinar quina de les deus pròtesis desenvolupa una millor funció mecànica i una millor adaptació biològica. És important remarcar que tot el disseny, sigui per a EMG o LBIA s'ha dut a terme de manera discreta sense fer servir Front-Ends comercials o integrats complexos més que l'amplificador d'instrumentació o ADC. En addició, el present treball inclou una primera estimació dels costos de producció i fabricació per a una sola unitat, càlculs de consums i funcionament (sorolls, CMRR del sistema i amplada de banda) i una simulació completa d'EMG i LBIA per observar com funciona i es du a terme cada etapa del circuit. Finalment, en tractar-se d'un equip mèdic, també s'ha revisat la normativa aplicable i se n'ha analitzat l'impacte ambiental, s'ha proposat i definit diferents punts per a futurs treballs, com podria ser la validació i testatge de l'equip, càlculs més aproximats de consums i perfilar la bill of materials (BOM) per a grans demandes de components.The purpose of this project is the hardware design of a portable medical device to measure electromyography (EMG) and localized bioimpedance (LBIA) signals, which will be used to evaluate the adaptability and progression of two knee prostheses (medial-pivot and ultra-congruent) in patients undergoing total knee arthroplasty at the Germans Trias i Pujol Hospital in Badalona. For this, the present work undercovers the relevant properties of the EMG and LBIA signals in order to define the characteristics of the medical equipment and thus optimize its electronic design. For the EMG measurements, a system made up of different stages has been designed and simulated. These phases work independently to acquire, amplify, filter, and adapt the EMG signal for its further digital processing. On the other hand, to obtain the bioimpedance values of different quadriceps muscles, a system composed of two large blocks has been designed; the first is the injection block, where a weak alternating current signal is generated and injected into the area to be measured, while the second block is the signal acquisition stage. The purpose of the latter is to acquire the voltage difference produced by the injection of current (mentioned above) and then obtain the bioimpedance from Ohm's law. All the signals are digitized from the STM32F407VG microcontroller, which will be in charge of processing and obtaining the key data to determine which of the two prostheses performs a better mechanical function and biological adaptation. It is important to note that the entire design, whether for EMG or LBIA, has been developed discreetly without using commercial Front-Ends or complex ICs other than the instrumentation amplifier or ADC. In addition, the thesis includes a first estimation of the production and manufacturing costs for a single unit, calculations of consumption and work operation (noise, CMRR of the system and bandwidth) and a complete simulation of EMG and LBIA to observe how it works on each stage for both circuits. Finally, as it is a medical device, the applicable regulations have also been reviewed and its environmental impact has been analysed. Additionally, different points have been proposed and defined for future work, such as the construction of the PCB and its respective validation, improving both the consumption calculations and the list of materials (BOM) for large component demands.El propósito de este proyecto es el diseño del Hardware de un dispositivo médico portátil para mediciones de electromiografía (EMG) y bioimpedancia localizada (LBIA), que se utilizará para estudiar la evolución de la adaptabilidad y funcionamiento de dos prótesis de rodilla (medial-pívot y ultracongruente) en pacientes operados de artroplastia total de rodilla en el Hospital Germans Trias i Pujol de Badalona. Para ello, se ha realizado un estudio exhaustivo sobre las propiedades de las señales de EMG y LBIA con la finalidad de definir las características del equipo médico y de esta forma, optimizar el diseño electrónico del mismo. Para la lectura de mediciones EMG, se ha diseñado y simulado un sistema constituido por distintas etapas, que trabajan independientemente para adquirir, amplificar, filtrar, y adaptarla señal EMG para su posterior procesado digital. Por otro lado, para obtener los valores de bioimpedancia de distintos músculos del cuádriceps, se ha diseñado un sistema compuesto por dos grandes bloques; el primero es el bloque de inyección, donde se genera y se inyecta una señal débil de corriente alterna en la zona a medir, mientras que el segundo bloque es la etapa de adquisición de señales. Esta última tiene como finalidad adquirir la diferencia de voltaje producido por la inyección de corriente (anteriormente mencionada) para después obtener la bioimpedancia a partir de la ley de ohm. Todas las señales son digitalizadas a partir del microcontrolador STM32F407VG, que se encargará de procesar y obtener los datos claves para determinar cuál de las dos prótesis desempeña una mejor función mecánica y adaptación biológica. Es importante remarcar que todo el diseño, ya sea para EMG o LBIA, se ha desarrollado de manera discreta sin usar Front-Ends comerciales o integrados complejos más que el amplificador de instrumentación o ADC. En adición, la tesis incluye una primera estimación de los costes de producción y fabricación para una sola unidad, cálculos de consumos y funcionamiento (ruidos, CMRR del sistema y ancho de banda) y una simulación completa de EMG y LBIA para observar cómo funciona y se desarrolla cada etapa de los distintos circuitos. Finalmente, al tratarse de un equipo médico, también se ha revisado la normativa aplicable y se ha analizado el impacto ambiental del mismo. Por último, se han propuesto y definido distintos puntos para futuros trabajos, como es la construcción de la PCB y su respectiva validación, realizar cálculos más aproximados de consumos y perfilar la lista de materiales (BOM) para grandes demandas de componentes

Sensor Technologies to Manage the Physiological Traits of Chronic Pain: A Review

Non-oncologic chronic pain is a common high-morbidity impairment worldwide and acknowledged as a condition with significant incidence on quality of life. Pain intensity is largely perceived as a subjective experience, what makes challenging its objective measurement. However, the physiological traces of pain make possible its correlation with vital signs, such as heart rate variability, skin conductance, electromyogram, etc., or health performance metrics derived from daily activity monitoring or facial expressions, which can be acquired with diverse sensor technologies and multisensory approaches. As the assessment and management of pain are essential issues for a wide range of clinical disorders and treatments, this paper reviews different sensor-based approaches applied to the objective evaluation of non-oncological chronic pain. The space of available technologies and resources aimed at pain assessment represent a diversified set of alternatives that can be exploited to address the multidimensional nature of pain.Ministerio de Economía y Competitividad (Instituto de Salud Carlos III) PI15/00306Junta de Andalucía PIN-0394-2017Unión Europea "FRAIL

Measuring and Analyzing Joint Acoustic Emissions from the Wrist

Joint acoustic emissions (JAEs) measured from the knee present promise as a method of noninvasive knee health quantification. This work adapts the methods developed for knee JAE measurements to the wrist - another joint commonly afflicted with injuries and degenerative disease. First, JAEs are measured using contact microphones at eight locations around the wrist during prescribed exercises (wrist flexion-extension and rotation) to find reliable and consistent wrist JAE measurement methods. The benchtop measurement setup established for knee JAE measurements is directly incorporated in this study. JAE signal strength is assessed using the signal-to-noise ratio (SNR). Then, nine features that have shown importance in JAE analysis are extracted, and the intraclass correlation coefficient (ICC) (model 3,k), coefficients of variability (CVs), and Jensen-Shannon (JS) divergence are used to assess the interrater repeatability, revealing both exercises produce JAEs and three locations demonstrated high JAE signal strength and repeatability. Second, a wrist wearable system is developed for high quality JAE sensing. Low-profile wide-band analog accelerometers to measure and analyze JAEs from two reliable locations on the wrist are sampled and saved on an SD card using a custom-designed printed circuit board (PCB). Using custom-developed casings, one accelerometer is clipped to the loop of a watchband for placement on the radius and the other is contained in a custom-developed grip for placement against the palm. Proper grip strength is reinforced real-time using LEDs. A flex sensor is secured along the volar side of the wrist for synchronously tracking wrist motion for improved cycle-by-cycle JAE analysis. This wrist wearable JAE sensing system is validated using SNR, ICC, CV, and JS divergence and compared to the benchtop setup. The developed wearable system is critical in moving toward monitoring wrist JAEs for at-home wrist joint health assessment.M.S

New Training Strategies and Evaluation Methods for Improving Health and Physical Performance

The aim of this Special Issue was to propose, on the basis of the evidence that the current literature provides, new training techniques and specific evaluation methods for the different populations practicing physical activity

XXII International Conference on Mechanics in Medicine and Biology - Abstracts Book

This book contain the abstracts presented the XXII ICMMB, held in Bologna in September 2022. The abstracts are divided following the sessions scheduled during the conference

Actas de SABI2020

Los temas salientes incluyen un marcapasos pulmonar que promete complementar y eventualmente sustituir la conocida ventilación mecánica por presión positiva (intubación), el análisis de la marchaespontánea sin costosos equipamientos, las imágenes infrarrojas y la predicción de la salud cardiovascular en temprana edad por medio de la biomecánica arterial