| 1. |
- Buendia, Ruben, 1982, et al.
(författare)
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Estimation of body fluids with bioimpedance spectroscopy: state of the art methods and proposal of novel methods
- 2015
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Ingår i: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 36:10
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Tidskriftsartikel (refereegranskat)abstract
- Determination of body fluids is a useful common practice in determination of disease mechanisms and treatments. Bioimpedance spectroscopy (BIS) methods are non-invasive, inexpensive and rapid alternatives to reference methods such as tracer dilution. However, they are indirect and their robustness and validity are unclear. In this article, state of the art methods are reviewed, their drawbacks identified and new methods are proposed. All methods were tested on a clinical database of patients receiving growth hormone replacement therapy. Results indicated that most BIS methods are similarly accurate (e.g. < 0.5 +/- 3.0% mean percentage difference for total body water) for estimation of body fluids. A new model for calculation is proposed that performs equally well for all fluid compartments (total body water, extra-and intracellular water). It is suggested that the main source of error in extracellular water estimation is due to anisotropy, in total body water estimation to the uncertainty associated with intracellular resistivity and in determination of intracellular water a combination of both.
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| 2. |
- Buendia, Ruben, 1982, et al.
(författare)
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Experimental Validation of a Method for Removing the Capacitive Leakage Artifact from Electrical Bioimpedance Spectroscopy Measurements
- 2010
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Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 21:11, s. 115802-
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Tidskriftsartikel (refereegranskat)abstract
- Often when performing electrical bioimpedance (EBI) spectroscopy measurements, the obtained EBI data present a hook-like deviation, which is most noticeable at high frequencies in the impedance plane. The deviation is due to a capacitive leakage effect caused by the presence of stray capacitances. In addition to the data deviation being remarkably noticeable at high frequencies in the phase and the reactance spectra, the measured EBI is also altered in the resistance and the modulus. If this EBI data deviation is not properly removed, it interferes with subsequent data analysis processes, especially with Cole model-based analyses. In other words, to perform any accurate analysis of the EBI spectroscopy data, the hook deviation mustbe properly removed. Td compensation is a method used to compensate the hook deviation present in EBI data; it consists of multiplying the obtained spectrum, Zmeas(ω), by a complex exponential in the form of exp(–jωTd). Although the method is well known and accepted, Td compensation cannot entirely correct the hook-like deviation; moreover, it lacks solid scientific grounds. In this work, the Td compensation method is revisited, and it is shown that it should not be used to correct the effect of a capacitive leakage; furthermore, a more developed approach for correcting the hook deviation caused by the capacitive leakage is proposed. The method includes a novel correcting expression and a process for selecting the proper values of expressions that are complex and frequency dependent. The correctness of the novel method is validated with the experimental data obtained from measurements from three different EBI applications. The obtained results confirm the sufficiency and feasibility of the correcting method.
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| 3. |
- Buendia, Rubén, et al.
(författare)
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Robustness study of the different immittance spectra and frequency ranges in bioimpedance spectroscopy analysis for assessment of total body composition.
- 2014
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Ingår i: Physiological measurement. - : IOP Publishing. - 1361-6579 .- 0967-3334. ; 35:7, s. 1373-95
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Tidskriftsartikel (refereegranskat)abstract
- The estimation of body fluids is a useful and common practice for assessment of disease status and therapy outcomes. Electrical bioimpedance spectroscopy (EBIS) methods are noninvasive, inexpensive and efficient alternatives for determination of body fluids. One of the main source of errors in EBIS measurements in the estimation of body fluids is capacitive coupling. In this paper an analysis of capacitive coupling in EBIS measurements was performed and the robustness of the different immittance spectra against it tested. On simulations the conductance (G) spectrum presented the smallest overall error, among all immittance spectra, in the estimation of the impedance parameters used to estimate body fluids. Afterwards the frequency range of 10-500kHz showed to be the most robust band of the G spectrum. The accuracy of body fluid estimations from the resulting parameters that utilized G spectrum and parameters provided by the measuring device were tested on EBIS clinical measurements from growth hormone replacement therapy patients against estimations performed with dilution methods. Regarding extracellular fluid, the correlation between each EBIS method and dilution was 0.93 with limits of agreement of 1.06 ± 2.95 l for the device, 1.10 ± 2.94 l for G [10-500kHz] and 1.04 ± 2.94 l for G [5-1000kHz]. Regarding intracellular fluid, the correlation between dilution and the device was 0.91, same as for G [10-500kHz] and 0.92 for G [5-1000kHz]. Limits of agreement were 0.12 ± 4.46 l for the device, 0.09 ± 4.45 for G [10-500kHz] and 0.04 ± 4.58 for G [5-1000kHz]. Such close results between the EBIS methods validate the proposed approach of using G spectrum for initial Cole characterization and posterior clinical estimation of body fluids status.
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| 4. |
- Ferreira, Javier, 1982-, et al.
(författare)
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AD5933-based Spectrometer for Electrical Bioimpedance Applications
- 2010
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596. ; 224:1, s. 012011-
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Konferensbidrag (refereegranskat)abstract
- o build an Electrical Bioimpedance (EBI) spectrometer using the Impedance Measurement System-On-Chip AD5933 together with a 4-Electrode Analog Front End (4E-AFE) has been proven practicable. Such small measurement devices can make possible several new applications of EBI technology, especially when combined with functional textiles, which can enable wearable applications for personal health and home monitoring. After the implementation and functional validation of the 4E-AFE-enabled spectrometer, the next natural step is to validate for which EBI applications the 4E-AFE-enabled system is suitable. To test the applicability of this novel spectrometer on several EBI applications, 2R1C equivalent models have been experimentally obtained and impedance spectroscopy measurements have been performed with the system under study and with the SFB7 EBI spectrometer manufactured by ImpediMed. The 2R1C circuit parameters have been estimated with the BioImp software from the spectra obtained with both EBI spectrometers and the estimated values have been compared with the original values used in each circuit model implementation. The obtained results indicated that the 4E-AFE-enabled system cannot beat the performance of the SFB7 in accuracy but it performs better in preciseness. In any case the overall performance indicates that the 4E-AFE-enabled system can perform spectroscopy measurements in the frequency range from 5 to 100 kHz.
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| 5. |
- Löfhede, Johan, 1978, et al.
(författare)
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Soft Textile Electrodes for EEG Monitoring
- 2010
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Ingår i: [12]10th IEEE International Conference on Information Technology and Applications.
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Konferensbidrag (refereegranskat)
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| 6. |
- Munoz-Gama, Jorge, et al.
(författare)
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Process mining for healthcare : Characteristics and challenges
- 2022
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Ingår i: Journal of Biomedical Informatics. - : Elsevier BV. - 1532-0464 .- 1532-0480. ; 127
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Tidskriftsartikel (refereegranskat)abstract
- Process mining techniques can be used to analyse business processes using the data logged during their execution. These techniques are leveraged in a wide range of domains, including healthcare, where it focuses mainly on the analysis of diagnostic, treatment, and organisational processes. Despite the huge amount of data generated in hospitals by staff and machinery involved in healthcare processes, there is no evidence of a systematic uptake of process mining beyond targeted case studies in a research context. When developing and using process mining in healthcare, distinguishing characteristics of healthcare processes such as their variability and patient-centred focus require targeted attention. Against this background, the Process-Oriented Data Science in Healthcare Alliance has been established to propagate the research and application of techniques targeting the data-driven improvement of healthcare processes. This paper, an initiative of the alliance, presents the distinguishing characteristics of the healthcare domain that need to be considered to successfully use process mining, as well as open challenges that need to be addressed by the community in the future.
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| 7. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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A Novel Approach for Estimation of Electrical Bioimpedance: Total Least Square
- 2007
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Ingår i: International Federation for Medical and Biological Engineering Proceedings. - 1680-0737. ; 17, s. 190-193, s. 190-193
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Konferensbidrag (refereegranskat)abstract
- There are several methods used for AC-impedance estimation in Electrical Bioimpedance measurements. In this paper we propose a novel method for digital estimation of electrical impedance based in the Total Least Square (TLS) technique and we carry out a performance comparison between the proposed method and the typical Digital Sine Correlation (DSC) method. The TLS method has been implemented using the Singular Value Decomposition approach and the performance of both methods have been compared in terms of robustness against noise and size of the data set. The results indicate that the TLS method shows a better performance for impedance estimation than the DSC with reduced set of measurement samples and high SNR levels, while its performance worsen for increasing number of samples and decreasing SNR. The DSC method exhibits a better robustness against noise, especially for increasing the number of data samples. The main observed advantage of the TLS method is that it suffers from less mathematical constrains than the DSC method, and since the noise levels in bioimpedance applications are not expected to be very high we conclude that the TLS method is a good choice as impedance estimator.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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Design-Build Experience-based Program in Biomedical Engineering as a practical example of Science for Professions.
- 2010
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Ingår i: The annual International Conference on Education and New Learning Technologies. - 9788461393862 ; , s. 110-
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Konferensbidrag (refereegranskat)abstract
- The University of Borås, Sweden, has endeavoured to build a repuration as a university that trains professionals who will contribute to the broader society, hence its motto “Science for Professions”. In keeping with thisambition the school of engineering has carried out a series of Design-Building Experiences (DBE) aimed to promote the development of specific engineering skills and attributes. In addition to subject specific attributes DBE aims at developing personal and interpersonal competences such as effective team work and communication. These generic competences have been selected from the CDIO syllabus. A total of three DBE activities have been implemented in aone-year master program in Biomedical Engineering. The learning outcomes that resulted from the implementation of the teaching-learning activity has been evaluated from the point of view of the students, through a questionnaire. The answers from the students suggest that the activity hasreached the intended goal, especially facilitating the development the students’ own personal and professional engineering skills and attributes. The results of this survey also indicate that students were concerned about peer assessment of the activity and its contribution to the final grade of the course. In general the implementation of the DBE was a success and provides us with new knowledge about implementing student centered learning methods in international master programs.
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| 14. |
- Seoane Martinez, Fernando, 1976
(författare)
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Electrical Bioimpedance Cerebral Monitoring: Effects of Hypoxia
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Electrical bioimpedance spectroscopy is one way to study the electrical properties of biological matter. Different applications of electrical bioimpedance measurements have already been used in both research and clinical scenarios i.e. impedance plethysmography, total body water contents, etc. The electrical properties of tissue reflect the electrical characteristics of the constituent elements of the tissue and depend on its structure. Thus study of the electrical properties not only makes it possible to differentiate among tissues but also to determine the tissue condition. During hypoxia/ischemia the cell activates a certain chain of mechanisms of cellular adaptation in response to the insult. A consequence of these response mechanisms is that the biochemical composition of the cellular environment is altered and the cells swell (cellular edema). These alterations affect the electrical properties of tissue and the changes can be observed through measurement of the electrical bioimpedance of the affected tissue. Based on these ideas, this research work studies the effects of hypoxia/ischemia on the brain electrical impedance. The aim is to obtain the fundamental knowledge that may lead to the development of useful clinical tools for cerebral monitoring based on electrical bioimpedance spectroscopy
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| 15. |
- Seoane Martinez, Fernando, 1976
(författare)
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Electrical Bioimpedance Cerebral Monitoring: Fundamental Steps towards Clinical Application
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neurologically related injuries cause a similar number of deaths as cancer, and brain damage is the second commonest cause of death in the world and probably the leading cause of permanent disability. The devastating effects of most cases of brain damage could be avoided if it were detected and medical treatment initiated in time. The passive electrical properties of biological tissue have been investigated for almost a century and electrical bioimpedance studies in neurology have been performed for more than 50 years. Even considering the extensive efforts dedicated to investigating potential applications of electrical bioimpedance for brain monitoring, especially in the last 20 years, and the specifically acute need for such non-invasive and efficient diagnosis support tools, Electrical Bioimpedance technology has not made the expected breakthrough into clinical application yet. In order to reach this stage in the age of evidence-based medicine, the first essential step is to demonstrate the biophysical basis of the method under study. The present research work confirms that the cell swelling accompanying the hypoxic/ischemic injury mechanism modifies the electrical properties of brain tissue, and shows that by measuring the complex electrical bioimpedance it is possible to detect the changes resulting from brain damage. For the development of a successful monitoring method, after the vital biophysical validation it is critical to have available the proper electrical bioimpedance technology and to implement an efficient protocol of use. Electronic instrumentation is needed for broadband spectroscopy measurements of complex electrical bioimpedance; the selection of the electrode setup is crucial to obtain clinically relevant measurements, and the proper biosignal analysis and processing is the core of the diagnosis support system. This work has focused on all these aspects since they are fundamental for providing the solid medico-technological background necessary to enable the clinical usage of Electrical Bioimpedance for cerebral monitoring.
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| 16. |
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| 17. |
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| 18. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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Simple voltage-controlled current source for wideband electrical bioimpedance spectroscopy: circuit dependences and limitations
- 2011
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Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 22:11
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the single Op-Amp with load-in-the-loop topology as a current source is revisited. This circuit topology was already used as a voltage-controlled current source (VCCS) in the 1960s but was left unused when the requirements for higher frequency arose among the applications of electrical bioimpedance (EBI). The aim of the authors is not only limited to show that with the currently available electronic devices it is perfectly viable to use this simple VCCS topology as a working current source for wideband spectroscopy applications of EBI, but also to identify the limitations and the role of each of the circuit components in the most important parameter of a current for wideband applications: the output impedance. The study includes the eventual presence of a stray capacitance and also an original enhancement, driving with current the VCCS. Based on the theoretical analysis and experimental measurements, an accurate model of the output impedance is provided, explaining the role of the main constitutive elements of the circuit in the source's output impedance. Using the topologies presented in this work and the proposed model, any electronic designer can easily implement a simple and efficient current source for wideband EBI spectroscopy applications, e. g. in this study, values above 150 k Omega at 1 MHz have been obtained, which to the knowledge of the authors are the largest values experimentally measured and reported for a current source in EBI at this frequency.
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| 19. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia
- 2005
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Ingår i: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 26:5, s. 849-863
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia/ischaemia is the most common cause of brain damage in neonates. Thousands of newborn children suffer from perinatal asphyxia every year. The cells go through a response mechanism during hypoxia/ischaemia, to maintain the cellular viability and, as a response to the hypoxic/ischaemic insult, the composition and the structure of the cellular environment are altered. The alterations in the ionic concentration of the intra- and extracellular and the consequent cytotoxic oedema, cell swelling, modify the electrical properties of the constituted tissue. The changes produced can be easily measured using electrical impedance instrumentation. In this paper, we report the results from an impedance spectroscopy study on the effects of the hypoxia on the perinatal brain. The transencephalic impedance, both resistance and reactance, was measured in newborn piglets using the four-electrode method in the frequency range from 20 kHz to 750 kHz and the experimental results were compared with numerical results from a simulation of a suspension of cells during cell swelling. The experimental results make clear the frequency dependence of the bioelectrical impedance, confirm that the variation of resistance is more sensitive at low than at high frequencies and show that the reactance changes substantially during hypoxia. The resemblance between the experimental and numerical results proves the validity of modelling tissue as a suspension of cells and confirms the importance of the cellular oedema process in the alterations of the electrical properties of biological tissue. The study of the effects of hypoxia/ischaemia in the bioelectrical properties of tissue may lead to the development of useful clinical tools based on the application of bioelectrical impedance technology.
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| 20. |
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| 21. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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The effect of the scalp and the skull bone in the total impedivity of the neonatal head and its implications in the detection of brain cellular edema
- 2005
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Ingår i: The 3rd European Medical and Biological Engineering Conference EMBEC´05. IFBME European Conference on BME. - Prague : IFMBE. - 1727-1983. ; 11:1
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Konferensbidrag (refereegranskat)abstract
- Hypoxic-ischemic encephalopathy (HIE) affects severely and frequently on newborns and yet not an efficient detection method has been implemented to assist the early initiation of a saving therapy. Invasive measurements of electrical bioimpedance can be used to detect the changes in the electrical properties of brain tissue as a consequence of the hypoxic cellular edema. In the case of non-invasive measurement the skull and the scalp will modified the measurements in a certain way. In this work, using numerical calculations on a four-concentric spheres model, we study the contribution of the scalp and the skull bone to the total equivalent impedivity, complex resistivity, of the neonatal head and its effect on the non-invasive detection of brain cellular edema. The results confirm the importance of the reactive part of the impedivity on the electrical bioimpedance monitoring of hypoxic brain damage.
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| 22. |
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