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An EIMG-EMG measurement system
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Journal of Biomechanics 2006, Vol. 39 (Suppl 1)
6741 We, 12:00-12:15 (P33) Estimation of heart muscle contractility by means of ICG a n d E C G J. Wtorek, A. Bujnowski, A. Maczynski. Biomedical Engineering Department,
Gdansk University of Technology, Gdansk, Poland Introduction: Heart muscle contractility can be used as a measure of heart muscle state. There are different approaches to measure contractility of a certain chamber, e.g. left ventricle. The most accepted is based on simultaneous measurement of pressure and volume of an examined chamber, mainly left ventricle. However, it requires an invasive measurements. The alternative approach based on simultaneous measurement of thoracic electrical impedance (ICG) and electrocardiogram (ECG) is considered. A similar index to Heather one has been proposed. The aim of the proposed index is to minimize an influence of other organs (e.g. aorta) and chambers of the heart, excluding the measured one, on results. Method: The measurement system consisting of ICG (tetrapolar technique) and ECG measurements modules has been developed. It enables simultaneous measurements and storing ICG and ECG waveforms in the format allowing their further processing, e.g. using Matlab. A few electrode configurations for impedance measurements based on thorax anatomy and sensitivity theorem have been chosen. A normalized contractility ratio, similar to Heather index, utilizing a selected parameters of processed ICG and referenced to ECG has been calculated for each electrode configuration. Results: It has been found that the proposed contractility ratio, similar the Heather one, strongly depends on electrode localization on the thorax in reference to placement of the heart. The value of Heather changed more than 20% for different electrode configuration. The variability of the Heather index has been calculated and found to be different for each electrode configuration. Moreover, it is differently influenced by the same physiological manoeuvres. Conclusions: It follows from our study that the impedance waveform, thus the value of its minimal time derivative, is influenced by electrode configuration and localization. It suggests that the electrode configuration proposed by Kubicek is inadequate for estimation heart contractility. It is due to contribution, however with different weight, all conductivity changes having its Iocalisation in the part of thorax limited by current ejecting electrodes. 6738
We, 12:15-12:30 (P33) measurement system J. Wtorek, A. Bujnowski, A. MaczySski. Biomedical Engineering Department,
An EIMG - EMG
Gdansk University of Technology, Gdansk, Poland Introduction: Electrical impedance measurements can be useful in the evaluation of muscle injury evoked by disease. It reflects, depending on frequency range, the properties and the internal structure of examined object. Objectives: To evaluate the potential applicability of multi-frequency electrical impedance myography (EIMG) and electromyography (EMG) in the assessment of both neurogenic and myopathic disease. Construction: A measurement system consisting of electromyography and multi-frequency impedance measurements modules has been developed. EMG module consists of two measurement channels. The impedance module, also consisting of two channels, enables measurement of the basal and contraction dependent impedance change components. The bioelectrical impedance measures, resistance and reactance, can be used to estimate total body water and, by extension, lean tissue and fat mass. Results: Impedance plots versus frequency over the 10 Hz to 100 kHz range have been recorded for the healthy and for the patients. The healthy leg showed qualitatively the same characteristic, the strong variation of impedance versus frequency. In contrast, the curves for the affected leg showed minimal changes in resistance and reactance over the 10 Hz to 100 kHz range. Conclusion: The developed system appears to be a very useful tool in evaluation of examined muscle diseases and disorders. Our findings indicate that the simultaneous recording of EIMG and EMG allow an noninvasive identification of muscle abnormalities. Future studies: We are examining a more differentiated group of patients. Examination involves recording both EIMG and EMG. A software being developed will enable to calculate EIMG or/and EMG based parameters for a more strictly basis, e.g. taking into account a spatial properties of measurement techniques due to reference results to a volume sampled during the study.
Oral Presentations
Workshop
The Finite Element Method in Biomedical Engineering, Biomechanics and Related Fields 7900 Sa, 10:00-10:30 (P3) Finite element analysis of the bone remodelling process considering bone condensing around osseointegrated dental implants M. Flach 1, P. Streckbein2 . 1University of Applied Sciences Koblenz, Germany, 2Deutsche Gesellschaft fEtr Implantologie im Zahn-Mund-Kieferbereich, Limburg, Germany Osseointegrated dental implants frequently show marginal bone resorption after the first few months of function. Reaching the implant stability the bone resorption will be stable at a level of two to four millimetres. The bone resorption can be explained by the high mechanical stresses in the marginal bone around the implant. To understand the bone remodelling process the stresses in the cortical and cancellous bone are calculated by finite element analysis. The bone remodelling process, driven by mechanical stimuli, is simulated using the soft kill method until implant stability is reached. The result of the calculated bone remodelling is given by the distribution of Young's modulus of the bone around the implant. The stresses at the marginal bone around the implant can be reduced by bone condensing. The stress distribution in the bone caused by "standard implants" without bone condensing and implants with bone condensing will be shown. The influence of bone condensing to the bone remodelling process and the distribution of Young's modulus of the bone after implant stability will be discussed. Partners: IGZ eG Implantologische Genossenschaft fur Zahn~rzte, Diez; Dr. Dr. Roland Streckbein, Pastpr~sident der DGI (Deutsche Gesellschaft fur Implantologie im Zahn-Mund-Kieferbereich), Limburg; Dr. Philipp Streckbein, Klinik fLir Mund-Kiefer-Gesichtschirurgie; Universit~t Giel~en (Direktor Prof. Dr. Dr. Peter Howald); Bego Implant Systems GmbH&Co. KG, Bremen. 7897 Sa, 10:30-11:00 (P3) Finite element simulations of skeletal muscle behaviour under tetanic a n d non-tetanic conditions M. BSI & S. Reese. Institute of Solid Mechanics, TU-Braunschweig, Germany The structure of a skeletal muscle can be considered as a complex hierarchical organisation in which thousands of muscle fibres are arranged within a connective tissue network. The single muscle fibres consist of many forceproducing cells, known as sarcomeres. However, these sarcomeres are a part of motor units and take care for the contraction of the whole muscle. The material behaviour of muscles is non-linear. Muscles can have large deformations in space, changing significantly their shape, so that the geometrical non-linearities must also be taken into account. The most authors use the finite element method to solve such materially and geometrically non-linear problems. In the present approach the finite element method is used too, where the material behaviour of the muscle is split into a so-called active and a passive part. To describe the passive part special unit cells consisting of one tetrahedral element and six truss elements have been derived. Additionally to these unit cells other truss elements are attached representing bundles of muscle fibres and therefore the active part of the material behaviour. To simulate a complex muscle structure, the muscle is discretised by the before described element ensembles. Depending on the discretisation it is possible to simulate the material behaviour of skeletal muscles (oriented fibres) as well as soft tissue behaviour (non-oriented fibres). 7899 Sa, 11:00-11:30 (P3) Different forms of material damping in a model of the middle e a r M. Bornitz 1, T. Zahnert 1, H.-J. Hardtke2. Technische Universit~t Dresden, 2Dept. of Medicine, Clinic of Oterhinolaryngology, 3Dept. of Solid State Mechanics, Dresden, Germany A FE model of the middle has been developed in order to get a better insight into the function of the middle ear and to perform simulations of different reconstruction techniques and middle ear prostheses. The aim is to find optimal prostheses and surgical techniques for the different kinds of middle ear reconstruction. For middle ear prostheses coupled to the malleus handle the complex vibration pattern of the tympanic membrane is essential for the energy transfer to the stapes footplate (and thus to the inner ear). Common simplifications in material
Journal of Biomechanics 2006, Vol. 39 (Suppl 1)
6741 We, 12:00-12:15 (P33) Estimation of heart muscle contractility by means of ICG a n d E C G J. Wtorek, A. Bujnowski, A. Maczynski. Biomedical Engineering Department,
Gdansk University of Technology, Gdansk, Poland Introduction: Heart muscle contractility can be used as a measure of heart muscle state. There are different approaches to measure contractility of a certain chamber, e.g. left ventricle. The most accepted is based on simultaneous measurement of pressure and volume of an examined chamber, mainly left ventricle. However, it requires an invasive measurements. The alternative approach based on simultaneous measurement of thoracic electrical impedance (ICG) and electrocardiogram (ECG) is considered. A similar index to Heather one has been proposed. The aim of the proposed index is to minimize an influence of other organs (e.g. aorta) and chambers of the heart, excluding the measured one, on results. Method: The measurement system consisting of ICG (tetrapolar technique) and ECG measurements modules has been developed. It enables simultaneous measurements and storing ICG and ECG waveforms in the format allowing their further processing, e.g. using Matlab. A few electrode configurations for impedance measurements based on thorax anatomy and sensitivity theorem have been chosen. A normalized contractility ratio, similar to Heather index, utilizing a selected parameters of processed ICG and referenced to ECG has been calculated for each electrode configuration. Results: It has been found that the proposed contractility ratio, similar the Heather one, strongly depends on electrode localization on the thorax in reference to placement of the heart. The value of Heather changed more than 20% for different electrode configuration. The variability of the Heather index has been calculated and found to be different for each electrode configuration. Moreover, it is differently influenced by the same physiological manoeuvres. Conclusions: It follows from our study that the impedance waveform, thus the value of its minimal time derivative, is influenced by electrode configuration and localization. It suggests that the electrode configuration proposed by Kubicek is inadequate for estimation heart contractility. It is due to contribution, however with different weight, all conductivity changes having its Iocalisation in the part of thorax limited by current ejecting electrodes. 6738
We, 12:15-12:30 (P33) measurement system J. Wtorek, A. Bujnowski, A. MaczySski. Biomedical Engineering Department,
An EIMG - EMG
Gdansk University of Technology, Gdansk, Poland Introduction: Electrical impedance measurements can be useful in the evaluation of muscle injury evoked by disease. It reflects, depending on frequency range, the properties and the internal structure of examined object. Objectives: To evaluate the potential applicability of multi-frequency electrical impedance myography (EIMG) and electromyography (EMG) in the assessment of both neurogenic and myopathic disease. Construction: A measurement system consisting of electromyography and multi-frequency impedance measurements modules has been developed. EMG module consists of two measurement channels. The impedance module, also consisting of two channels, enables measurement of the basal and contraction dependent impedance change components. The bioelectrical impedance measures, resistance and reactance, can be used to estimate total body water and, by extension, lean tissue and fat mass. Results: Impedance plots versus frequency over the 10 Hz to 100 kHz range have been recorded for the healthy and for the patients. The healthy leg showed qualitatively the same characteristic, the strong variation of impedance versus frequency. In contrast, the curves for the affected leg showed minimal changes in resistance and reactance over the 10 Hz to 100 kHz range. Conclusion: The developed system appears to be a very useful tool in evaluation of examined muscle diseases and disorders. Our findings indicate that the simultaneous recording of EIMG and EMG allow an noninvasive identification of muscle abnormalities. Future studies: We are examining a more differentiated group of patients. Examination involves recording both EIMG and EMG. A software being developed will enable to calculate EIMG or/and EMG based parameters for a more strictly basis, e.g. taking into account a spatial properties of measurement techniques due to reference results to a volume sampled during the study.
Oral Presentations
Workshop
The Finite Element Method in Biomedical Engineering, Biomechanics and Related Fields 7900 Sa, 10:00-10:30 (P3) Finite element analysis of the bone remodelling process considering bone condensing around osseointegrated dental implants M. Flach 1, P. Streckbein2 . 1University of Applied Sciences Koblenz, Germany, 2Deutsche Gesellschaft fEtr Implantologie im Zahn-Mund-Kieferbereich, Limburg, Germany Osseointegrated dental implants frequently show marginal bone resorption after the first few months of function. Reaching the implant stability the bone resorption will be stable at a level of two to four millimetres. The bone resorption can be explained by the high mechanical stresses in the marginal bone around the implant. To understand the bone remodelling process the stresses in the cortical and cancellous bone are calculated by finite element analysis. The bone remodelling process, driven by mechanical stimuli, is simulated using the soft kill method until implant stability is reached. The result of the calculated bone remodelling is given by the distribution of Young's modulus of the bone around the implant. The stresses at the marginal bone around the implant can be reduced by bone condensing. The stress distribution in the bone caused by "standard implants" without bone condensing and implants with bone condensing will be shown. The influence of bone condensing to the bone remodelling process and the distribution of Young's modulus of the bone after implant stability will be discussed. Partners: IGZ eG Implantologische Genossenschaft fur Zahn~rzte, Diez; Dr. Dr. Roland Streckbein, Pastpr~sident der DGI (Deutsche Gesellschaft fur Implantologie im Zahn-Mund-Kieferbereich), Limburg; Dr. Philipp Streckbein, Klinik fLir Mund-Kiefer-Gesichtschirurgie; Universit~t Giel~en (Direktor Prof. Dr. Dr. Peter Howald); Bego Implant Systems GmbH&Co. KG, Bremen. 7897 Sa, 10:30-11:00 (P3) Finite element simulations of skeletal muscle behaviour under tetanic a n d non-tetanic conditions M. BSI & S. Reese. Institute of Solid Mechanics, TU-Braunschweig, Germany The structure of a skeletal muscle can be considered as a complex hierarchical organisation in which thousands of muscle fibres are arranged within a connective tissue network. The single muscle fibres consist of many forceproducing cells, known as sarcomeres. However, these sarcomeres are a part of motor units and take care for the contraction of the whole muscle. The material behaviour of muscles is non-linear. Muscles can have large deformations in space, changing significantly their shape, so that the geometrical non-linearities must also be taken into account. The most authors use the finite element method to solve such materially and geometrically non-linear problems. In the present approach the finite element method is used too, where the material behaviour of the muscle is split into a so-called active and a passive part. To describe the passive part special unit cells consisting of one tetrahedral element and six truss elements have been derived. Additionally to these unit cells other truss elements are attached representing bundles of muscle fibres and therefore the active part of the material behaviour. To simulate a complex muscle structure, the muscle is discretised by the before described element ensembles. Depending on the discretisation it is possible to simulate the material behaviour of skeletal muscles (oriented fibres) as well as soft tissue behaviour (non-oriented fibres). 7899 Sa, 11:00-11:30 (P3) Different forms of material damping in a model of the middle e a r M. Bornitz 1, T. Zahnert 1, H.-J. Hardtke2. Technische Universit~t Dresden, 2Dept. of Medicine, Clinic of Oterhinolaryngology, 3Dept. of Solid State Mechanics, Dresden, Germany A FE model of the middle has been developed in order to get a better insight into the function of the middle ear and to perform simulations of different reconstruction techniques and middle ear prostheses. The aim is to find optimal prostheses and surgical techniques for the different kinds of middle ear reconstruction. For middle ear prostheses coupled to the malleus handle the complex vibration pattern of the tympanic membrane is essential for the energy transfer to the stapes footplate (and thus to the inner ear). Common simplifications in material