Abstracts – BMT 2019 – Frankfurt am Main, September 25–26 • DOI 10.1515/bmt-2019-6020 Biomed. Eng.-Biomed. Tech. 2019; 64(s2): S94–S97 • © by Walter de Gruyter • Berlin • Boston S94
Design of an Auscultation System for Phonoangiography of the Carotid Artery
Thomas Sühn, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, [email protected] Arathi Sreenivas, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, ara- [email protected] Naghmeh Mahmoodian, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, [email protected] Iván Maldonado, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, [email protected] Axel Boese, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, axel.bo- [email protected] Alfredo Illanes, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, alfredo.il- [email protected] Michael Bloxton, Bloxton Investment Group, LLC., San Diego, United States, [email protected] Michael Friebe, INKA, Institute of Medical Technology, Otto-von-Guericke University, Magdeburg, Germany, Mi- [email protected]
Cerebrovascular diseases such as stenosis, atherosclerosis or distention of the carotid artery are accountable for about 1 million death per year across Europe. Diagnostic tools like ultrasound imaging, angiography or magnetic resonance based imaging require specific hardware and highly depend on the experience of the examining clinician. In contrast ausculta- tion with a stethoscope can be used to screen for and subjectively quantify bruits – audible vascular sounds associated with turbulent blood flow in the arteries. Dynamical changes in the flow due to pathological narrowing of the vessel can indicate the need for additional diagnostic investigations. A reliable auscultation setup is prerequisite to ensure high signal quality, adequate processing and the objective evaluation of a still subjectively assessed audible signal. We propose a computer assisted auscultation device for the characterisation of carotid bruits to facilitate the objective assessment, screening and monitoring of long-term changes in the vessel condition. Acoustic signals are acquired using two integrated audio sensors in combination with a particular mechanical setup to ensure a reliable interface to the skin. Data are trans- ferred to a mini computer for real-time visualisation and evaluation of sensor position and signal quality before recording starts. Main goal of this work are design considerations regarding the mechanical interface of the proposed system to the skin. An experimental setup was used to compare the signal quality and morphology of different setups to a commercially available digital stethoscope as reference system. A combined system with two different interface configurations is pro- posed. Current limitations of the system and potential improvements are discussed. Abstracts – BMT 2019 – Frankfurt am Main, September 25–26 • DOI 10.1515/bmt-2019-6020 Biomed. Eng.-Biomed. Tech. 2019; 64(s2): S94–S97 • © by Walter de Gruyter • Berlin • Boston S95
Investigation of a non-invasive venous blood flow measurement device using thermal mass measurement principles
Simon Dangelmaier, Institut für Medizingerätetechnik (IMT), Universität Stuttgart, Stuttgart, Germany, [email protected] Jens Anders, Institut für intelligente Sensorik (IIS), Universität Stuttgart, Stuttgart, Germany, [email protected] Peter P. Pott, Institut für Medizingerätetechnik (IMT), Universität Stuttgart, Stuttgart, Germany, [email protected] Kent W. Stewart, Institut für Medizingerätetechnik (IMT), Universität Stuttgart, Stuttgart, Germany, [email protected]
Venous blood circulation can be restricted due to various conditions such as thrombosis and blood clots. However, cur- rent non-invasive methods for determining venous blood flow are limited to be either very inaccurate (capillary nail re- fill test) or expensive venous Doppler ultrasound, reducing the accessibility to quality diagnostic tools. This paper in- vestigates using a new alternative method of thermal mass flow principles to determine venous blood flow.
A simplified finite element (FE) model and simulation are created to determine the operating behaviour and expected response of a thermal mass flow meter with venous blood flow under the skin. An initial prototype of a thermal mass venous blood flow meter is designed using a Peltier-element and thermistor. Initial tests were done on ten subjects iden- tifying the presence of blood flow, testing the devices basic functionality and performance.
Simulations showed small differences in temperature for a change in flow rate (0.005 K /(cm/s)), and as a result, the dif- ference between no and typical venous blood flow (10 cm/s) was 0.05 K. In addition, the potential variation in absolute heat transfer due to different vein sizes proved to be a significant factor. The initial prototype proved to be functional, heating the skin to 42°C and detecting rises in temperature downstream when blood flow was released of +1.0 ± 0.6 K (after 60 s), compared to when blood was not flowing.
The simplified FEM model of venous blood flow proves the thermal mass blood flow device is feasible. However, vari- ations in temperature due to intra-patient variability in physiology showed that measurements need to be made patient- specific. An initial prototype proved to be able to detect the presence of blood flow in all subjects. However, more work is required to be able to determine blood flow rate.
Abstracts – BMT 2019 – Frankfurt am Main, September 25–26 • DOI 10.1515/bmt-2019-6020 Biomed. Eng.-Biomed. Tech. 2019; 64(s2): S94–S97 • © by Walter de Gruyter • Berlin • Boston S96
A novel device to measure respiration induced changes of circumferences
Bernhard Laufer, Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany, [email protected] Sabine Krueger-Ziolek, Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Ger- many, [email protected] Paul David Docherty, Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand, [email protected] Fabian Hoeflinger, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany, fabian.hoe- [email protected] Leonhard Reindl, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany, [email protected] Knut Moeller, Institute of Technical Medicine (ITeM), Furtwangen University, Villingen-Schwenningen, Germany, [email protected]
Anthropometric circumference measurements of the human body can be done with various measurement systems of dif- ferent complexity. Very complex systems, such as computer tomography or optoelectronic plethysmography can be uti- lized to measure circumferences or even very simple systems like the measuring tape can be used. But each of these systems show disadvantages in the measurement of respiration induced changes of the human upper body. Either the costs, the restriction to a specified measurement area or the handling of the system are all important drawbacks. Thus, in this feasibility study we introduce a novel, non-invasive and wearable approach to measure changes in circum- ferences of thorax or abdomen. Based on small optical encoders a measurement system (a belt) was developed, which is able to measure changes in circumferences. To evaluate this measuring belt, a subject did various thoracical breaths with the goal to breathe dissimilar tidal volumes. Dissimilar tidal volumes generate different thoracical circumferences, which were measured by the belt and simultaneously, by an optoelectronic plethysmograph as a reference. The results of the belt were in high conformity with the reference system. A coefficient of determination (adjusted R2 = 0.99) and a mean squared error of 0.23 mm showed in an impressive manner that the belt is capable to measure changes in circumferences in high accuracy. Thus, a couple of respiratory parameters, such as the respiratory rate can be obtained, based on the circumferential changes of the thorax. This system could be used for surveillance tasks or to analyse respiratory parame- ters during sports.
Abstracts – BMT 2019 – Frankfurt am Main, September 25–26 • DOI 10.1515/bmt-2019-6020 Biomed. Eng.-Biomed. Tech. 2019; 64(s2): S94–S97 • © by Walter de Gruyter • Berlin • Boston S97
Intelligent Assistant System for the Automatic Assessment of Fall Processes in Sports Climbing for Injury Prevention based on Inertial Sensor Data
Michael Munz, University of Applied Sciences, Institute of Medical Engineering and Mechatronics, Ulm, Germany, [email protected] Thomas Engleder, University of Applied Sciences, Institute of Medical Engineering and Mechatronics, Ulm, Germany, [email protected]
Sports climbing is a very popular leisure activity for all generations. For ambitious climbers, falling is a normal part of the sport. Belaying prevents the climber from falling on the floor or on obstacles. Nevertheless, injuries of legs, arms, the back or other parts of the body are common when hitting the wall. These injuries can be prevented by training both the climber and the belayer. Frequent mistakes are, besides others: jumping too far away from the wall (climber), belay- ing by shortening the rope or moving away from the wall, resulting in a hard impact into the rope. This impulse leads to an acceleration of the climber towards the wall, increasing the impact energy. In order to prevent such injuries, it is important that falling and belaying, like the dynamic belaying technique, are being trained. But as actions happen at a very high speed, an objective feedback is hard to provide. This work presents a com- pletely new approach. We developed a sensor based system which provides an automatic assessment of the whole pro- cess. Inertial measurement units (IMUs) are placed on the climber’s hip and both legs as well as on the belayers hip. The sensor data is automatically segmented into separate phases of the fall (initiation, impact to rope, breaking phase, impact to wall) and several quality features of both climber and belayer are extracted. Those features comprise move- ment of the belayer, strength of the impact into the rope, jump strength and direction of the climber. Additionally, the whole three-dimensional trajectory is provided for review. These features can be used for an objective feedback to the athletes or coach. To the best of the authors’ knowledge, this is the very first system that is able to perform such an as- sessment in sports climbing to prevent injuries.