Change search
Refine search result
1 - 48 of 48
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Abtahi, F
    et al.
    Seoane, F
    University of Borås, School of Engineering.
    Lindecrantz, K
    University of Borås, School of Engineering.
    Electrical bioimpedance spectroscopy in time-variant systems: Is undersampling always a problem?2014In: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 5, no 1, p. 28-33Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied mainly by using the frequency-sweep technique, across a range of many different applications. Traditionally, the tissue under study is considered to be time-invariant and dynamic changes of tissue activity are ignored by treating the changes as a noise source. A new trend in EBIS is simultaneous electrical stimulation with several frequencies, through the application of a multi-sine, rectangular or other waveform. This method can provide measurements fast enough to sample dynamic changes of different tissues, such as cardiac muscle. This high sampling rate comes at a price of reduction in SNR and the increase in complexity of devices. Although the frequency-sweep technique is often inadequate for monitoring the dynamic changes in a variant system, it can be used successfully in applications focused on the time-invariant or slowly-variant part of a system. However, in order to successfully use frequency-sweep EBIS for monitoring time-variant systems, it is paramount to consider the effects of aliasing and especially the folding of higher frequencies, on the desired frequency e.g. DC level. This paper discusses sub-Nyquist sampling of thoracic EBIS measurements and its application in the case of monitoring pulmonary oedema. It is concluded that by considering aliasing, and with proper implementation of smoothing filters, as well as by using random sampling, frequency-sweep EBIS can be used for assessing time-invariant or slowly-variant properties of time-variant biological systems, even in the presence of aliasing. In general, undersampling is not always a problem, but does always require proper consideration.

  • 2. Amer-Wåhlin, I
    et al.
    Kjellmer, I
    Maršál, K
    Olofsson, P
    Rosén, Karl Gustaf
    University of Borås, School of Engineering.
    Swedish randomized controlled trial of cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram revisited: analysis of data according to standard versus modified intention-to-treat principle.2011In: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, ISSN 0001-6349, Vol. 90, no 9, p. 990-996Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To undertake a renewed analysis of data from the previously published Swedish randomized controlled trial on intrapartum fetal monitoring with cardiotocography (CTG-only) vs. CTG plus ST analysis of fetal electrocardiogram (CTG+ST), using current standards of intention-to-treat (ITT) analysis and to compare the results with those of the modified ITT (mITT) and per protocol analyses. METHODS: Renewed extraction of data from the original database including all cases randomized according to primary case allocation (n=5 049). MAIN OUTCOME MEASURE: Metabolic acidosis in umbilical artery at birth (pH <7.05, base deficit in extracellular fluid >12.0 mmol/l) including samples of umbilical vein blood or neonatal blood if umbilical artery blood was missing. RESULTS: The metabolic acidosis rates were 0.66% (17 of 2 565) and 1.33% (33 of 2 484) in the CTG+ST and CTG-only groups, respectively [relative risk (RR) 0.50; 95% confidence interval (CI) 0.28-0.88; p=0.019]. The original mITT gave RR 0.47, 95%CI 0.25-0.86 (p=0.015), mITT with correction for 10 previously misclassified cases RR 0.48, 95%CI 0.24-0.96 (p=0.038) and per protocol analysis RR 0.40, 95%CI 0.20-0.80 (p=0.009). The level of significance of the difference in metabolic acidosis rates between the two groups remained unchanged in all analyses. CONCLUSION: Re-analysis of data according to the ITT principle showed that regardless of the method of analysis, the Swedish randomized controlled trial maintained its ability to demonstrate a significant reduction in metabolic acidosis rate when using CTG+ST analysis for fetal surveillance in labor.

  • 3. Ayres-de-Campos, D.
    et al.
    Ugwumadu, A.
    Banfield, P.
    Lynch, P.
    Amin, P.
    Horwell, D.
    Costa, A.
    Santos, C.
    Bernardes, J.
    Rosen, Karl Gustaf
    University of Borås, School of Engineering.
    A randomised clinical trial of intrapartum fetal monitoring with computer analysis and alerts versus previously available monitoring2010In: BMC Pregnancy and Childbirth, ISSN 1471-2393, E-ISSN 1471-2393, Vol. 10, no 71Article in journal (Refereed)
    Abstract [en]

    Background: Intrapartum fetal hypoxia remains an important cause of death and permanent handicap and in a significant proportion of cases there is evidence of suboptimal care related to fetal surveillance. Cardiotocographic (CTG) monitoring remains the basis of intrapartum surveillance, but its interpretation by healthcare professionals lacks reproducibility and the technology has not been shown to improve clinically important outcomes. The addition of fetal electrocardiogram analysis has increased the potential to avoid adverse outcomes, but CTG interpretation remains its main weakness. A program for computerised analysis of intrapartum fetal signals, incorporating real-time alerts for healthcare professionals, has recently been developed. There is a need to determine whether this technology can result in better perinatal outcomes. Methods/design: This is a multicentre randomised clinical trial. Inclusion criteria are: women aged ≥ 16 years, able to provide written informed consent, singleton pregnancies ≥ 36 weeks, cephalic presentation, no known major fetal malformations, in labour but excluding active second stage, planned for continuous CTG monitoring, and no known contra-indication for vaginal delivery. Eligible women will be randomised using a computer-generated randomisation sequence to one of the two arms: continuous computer analysis of fetal monitoring signals with real-time alerts (intervention arm) or continuous CTG monitoring as previously performed (control arm). Electrocardiographic monitoring and fetal scalp blood sampling will be available in both arms. The primary outcome measure is the incidence of fetal metabolic acidosis (umbilical artery pH < 7.05, BDecf > 12 mmol/L). Secondary outcome measures are: caesarean section and instrumental vaginal delivery rates, use of fetal blood sampling, 5-minute Apgar score < 7, neonatal intensive care unit admission, moderate and severe neonatal encephalopathy with a marker of hypoxia, perinatal death, rate of internal monitoring, tracing quality, and signal loss. Analysis will follow an intention to treat principle. Incidences of primary and secondary outcomes will be compared between groups. Assuming a reduction in metabolic acidosis from 2.8% to 1.8%, using a two-sided test with alpha = 0.05, power = 0.80, and 10% loss to follow-up, 8133 women need to be randomised. Discussion: This study will provide evidence of the impact of intrapartum monitoring with computer analysis and real-time alerts on the incidence of adverse perinatal outcomes, intrapartum interventions and signal quality. (Current controlled trials ISRCTN42314164)

  • 4.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Interactive Textile Structures: Creating Multifunctional Textiles based on Smart Materials2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Textiles of today are materials with applications in almost all our activities. We wear clothes all the time and we are surrounded with textiles in almost all our environments. The integration of multifunctional values in such a common material has become a special area of interest in recent years. Smart Textile represents the next generation of textiles anticipated for use in several fashion, furnishing and technical textile applications. The term smart is used to refer to materials that sense and respond in a pre-defined manner to environmental stimuli. The degree of smartness varies and it is possible to enhance the intelligence further by combining these materials with a controlling unit, for example a microprocessor. As an interdisciplinary area Smart Textile includes design spaces from several areas; the textile design space, the information technology design space and the design space of material science. This thesis addresses how Smart Textiles affect the textile design space; how the introduction of smart materials and information technology affects the creation of future textile products. The aim is to explore the convergence between textiles, smart materials and information technology and to contribute to providing a basis for future research in this area. The research method is based on a series of interlinked experiments designed through the research questions and the research objects. The experiments are separated into two different sections: interactive textile structures and health monitoring. The result is a series of basic methods for how interactive textile structures are created and a general system for health monitoring. Furthermore the result consists of a new design space, advanced textile design. In advanced textile design the focus is set on the relation between the different natures of a textile object: its physical structure and its structure in the context of design and use.

  • 5. Blad, Sofia
    et al.
    Welin, Anna-Karin
    Kjellmer, Ingemar
    Rosén, Karl-Gustaf
    University of Borås, School of Engineering.
    Mallard, Carina
    ECG and heart rate variability changes in preterm and near-term fetal lamb following LPS exposure2008In: Reproductive Sciences, ISSN 1933-7191, E-ISSN 1933-7205, Vol. 15, no 6, p. 572-583Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to evaluate the myocardial response in the preterm and near-term fetal lamb with infection. Chronically instrumented fetal lambs were exposed to lipopolysaccharide (LPS), and the fetal electrocardiogram (FECG) ST waveform was examined using STAN. Fetal heart rate variability (FHRV) was automatically analyzed by adapting a polynomial function to the RR sequence in the FECG. Preterm fetuses exposed to >90 ng/kg LPS died within 8 hours of LPS administration, a response not seen in near-term fetuses. In both surviving and nonsurviving preterm fetuses, cardiovascular responses were characterized by decreased arterial pressure, negative T waves, and tachycardia accompanied by an increase in FHRV. Similar changes were not observed in the near-term fetuses after LPS. The study shows that preterm lambs are more sensitive to LPS in terms of myocardial/cardiovascular response than the more mature fetuses are. High FHRV and negative ST waveform seem to characterize the LPS-induced stress response in preterm fetuses.

  • 6.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    Seoane, Fernando
    University of Borås, School of Engineering.
    Cole Parameter Estimation from the Modulus of the Electrical Bioimpeadance for Assessment of Body Composition. A Full Spectroscopy Approach2011In: Journal of Electrical Bioimpedance, ISSN 1891-5469, E-ISSN 1891-5469, Vol. 2, p. 72-78Article in journal (Refereed)
    Abstract [en]

    Activities around applications of Electrical Bioimpedance Spectroscopy (EBIS) have proliferated in the past decade significantly. Most of these activities have been focused in the analysis of the EBIS measurements, which eventually might enable novel applications. In Body Composition Assessment (BCA), the most common analysis approach currently used in EBIS is based on the Cole function, which most often requires curve fitting. One of the most implemented approaches for obtaining the Cole parameters is performed in the impedance plane through the geometrical properties that the Cole function exhibit in such domain as depressed semi-circle. To fit the measured impedance data to a semi-circle in the impedance plane, obtaining the Cole parameters in an indirect and sequential manner has several drawbacks. Applying a Non-Linear Least Square (NLLS) iterative fitting on the spectroscopy measurement, obtains the Cole parameters considering the frequency information contained in the measurement. In this work, from experimental total right side EBIS measurements, the BCA parameters have been obtained to assess the amount and distribution of whole body fluids. The values for the BCA parameters have been obtained using values for the Cole parameters estimated with both approaches: circular fitting on the impedance plane and NLLS impedance-only fitting. The comparison of the values obtained for the BCA parameters with both methods confirms that the NLLS impedance-only is an effective alternative as Cole parameter estimation method in BCA from EBIS measurements. Using the modulus of the Cole function as the model for the fitting would eliminate the need for performing phase detection in the acquisition process, simplifying the hardware specifications of the measurement instrumentation when implementing a bioimpedance spectrometer.

  • 7. Buendia, Ruben
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Gil-Pita, Roberto
    A Novel Approach for Removing the Hook Effect Artefact from Electrical Bioimpedance Spectroscopy Measurements2009In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2009Conference paper (Refereed)
    Abstract [en]

    Very often in Electrical Bioimpedance (EBI) spectroscopy measurements the presence of stray capacitances creates a measurement artefact commonly known as Hook Effect. Such an artefact creates a hook-alike deviation of the EBI data noticeable when representing the measurement on the impedance plane. Such Hook Effect is noticeable at high frequencies but it also causes a data deviation at lower measurement frequencies. In order to perform any accurate analysis of the EBI spectroscopy data, the influence of the Hook Effect must be removed. An established method to compensate the hook effect is the well known Td compensation, which consist on multiplying the obtained spectrum, Zmeas() by a complex exponential in the form of exp[jTd]. Such a method cannot correct entirely the Hook Effect since the hook-alike deviation occurs a broad frequency range in both magnitude and phase of the measured impedance, and by using a real value for Td. First, a real value only modifies the phase of the measured impedance and second, it can only correct the Hook Effect at a single frequency. In addition, the process to select a value for Td by an iterative process with the aim to obtain the best Cole fitting lacks solid scientific grounds. In this work the Td compensation method is revisited and a modified approach for correcting the Hook Effect that includes a novel method for selecting the correcting values is proposed. The initial validation results confirm that the proposed method entirely corrects the Hook Effect at all frequencies.

  • 8.
    Buendia, Ruben
    et al.
    University of Borås, School of Engineering.
    Seoane Martinéz, Fernando
    University of Borås, School of Engineering.
    Harris, M.
    Caffarel, J.
    Gil, R.
    Hook Effect Correction & Resistance-based Cole Fitting Prior Cole Model-based Analysis: Experimental Validation2010Conference paper (Refereed)
  • 9.
    Ferreira Gonzalez, Javier
    University of Borås, School of Engineering.
    Textile-enabled Bioimpedance Instrumentation for Personalised Health Monitoring Applications2013Licentiate thesis, monograph (Other academic)
    Abstract [en]

    A growing number of factors, including the costs, technological advancements, an ageing population, and medical errors are leading industrialised countries to invest in research on alternative solutions to improving their health care systems and increasing patients’ life quality. Personal Health System (PHS) solutions envision the use of information and communication technologies that enable a paradigm shift from the traditional hospital-centred healthcare delivery model toward a preventive and person-centred approach. PHS offers the means to follow patient health using wearable, portable or implantable systems that offer ubiquitous, unobtrusive bio-data acquisition, allowing remote access to patient status and treatment monitoring.Electrical Bioimpedance (EBI) technology is a non-invasive, quick and relatively affordable technique that can be used for assessing and monitoring different health conditions, e.g., body composition assessments for nutrition. EBI technology combined with state-of-the-art advances in sensor and textile technology are fostering the implementation of wearable bioimpedance monitors that use functional garments for the implementation of personalised healthcare applications.This research studies the development of a portable EBI spectrometer that can use dry textile electrodes for the assessment of body composition for the purposes of clinical uses. The portable bioimpedance monitor has been developed using the latest advances in system-on-chip technology for bioimpedance spectroscopy instrumentation. The obtained portable spectrometer has been validated against commercial spectrometer that performs total body composition assessment using functional textrode garments.The development of a portable Bioimpedance spectrometer using functional garments and dry textile electrodes for body composition assessment has been shown to be a feasible option. The availability of such measurement systems bring closer the real implementation of personalised healthcare systems.

  • 10.
    Ferreira Gonzalez, Javier
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    AD5933-Based Electrical Bioimpedance Spectrometer. Towards Textile-Enabled Applications.2011Conference paper (Refereed)
  • 11.
    Ferreira, Javier
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Ansede, Antonio
    Bragos, Ramon
    AD5933-based Spectrometer for Electrical Bioimpedance Applications2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    To 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 equivalents 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.

  • 12. Flisberg, Anders
    et al.
    Kjellmer, I
    Löfhede, Johan
    University of Borås, School of Engineering.
    Löfgren, N
    Rosa-Zurera, M
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Thordstein, M
    Does indomethacin for closure of patent ductus arteriosus affect cerebral function?2010In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 99, no 10, p. 1493-1497Article in journal (Refereed)
    Abstract [en]

    Objective: To study whether indomethacin used in conventional dose for closure of patent ductus arteriosus affects cerebral function measured by Electroencephalograms (EEG) evaluated by quantitative measures. Study design: Seven premature neonates with haemodynamically significant persistent ductus arteriosus were recruited. EEG were recorded before, during and after an intravenous infusion of 0.2 mg/kg indomethacin over 10 min. The EEG was analysed by two methods with different degrees of complexity for the amount of low-activity periods (LAP, “suppressions”) as an indicator of affection of cerebral function. Results: Neither of the two methods identified any change in the amount of LAPs in the EEG as compared to before the indomethacin infusion. Conclusion: Indomethacin in conventional dose for closure of patent ductus arteriosus does not affect cerebral function as evaluated by quantitative EEG.

  • 13. Gund, Ann
    et al.
    Sjöqvist, Bengt Arne
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Ekman, Inger
    Care@Distance: Disease Mangement för hjärtsviktspatienter i hemmet2007Conference paper (Refereed)
    Abstract [sv]

    Antalet äldre i samhället ökar, och med det kostnaderna p.g.a. kroniska åldersrelaterade sjukdomstillstånd. Ett sådant tillstånd är hjärtsvikt vilket drabbar ca 2 % av västvärldens befolkning. Forskning har visat att IT-baserad hemvård för s.k. Disease Management kan resultera i minskade kostnader så väl som ökad livskvalitet hos patienterna. Inom projektet Care@Distance är avsikten att utforma ett sådant system där tyngden ligger dels på regelbundna dagliga enkla mätningar av fysiologiskt relaterade parametrar såsom vikt och blodtryck, och dels på formulär där patienten svarar på några enkla frågor om det upplevda tillståndet. Syftet är att få med både objektiv och subjektiv information som sedan kan ligga till grund för en förbättrad vård av den enskilde patienten. Systemet utformas främst för att skapa underlag för en bättre långsiktig behandling, terapi och för uppföljning av Treatment Compliance, men även för att hantera akuta situationer genom t.ex. larm till vårdgivaren. Under projektets tid har ett samarbete med DAGA-kliniken på Östra sjukhuset upprättats, genom bl.a. diskussioner om frågeformulärets utformning. Under våren 2007 har även två förstudier genomförts på kliniken, den första med inriktning mot patientdelen av systemet, och den andra mot vårdgivarsidan. Studien visar att patientdelen är lätthanterad ur patientsynpunkt samt att intresse för systemet finns. Även på vårdgivarsidan är resultaten positiva när det gäller design, funktioner och intresse, men utrymme för förbättringar finns. Fortsatta studier i form av ett längre försök i hemmet hos patienter är planerat under sommaren och hösten 2007. Under sommaren kommer även patientdelen att vidareutvecklas med ny programvara. Ett framtida projekt innefattar att utveckla en metod för att utnyttja EBI (Elektrisk Bio-Impedans). Med relativt enkla och robusta mätningar förväntas mycket användbar och relevant information om sjukdomstillståndet kunna erhållas med denna metod, men detta kräver att ny sensorteknik utvecklas för hemmiljön.

  • 14. Kro, G.
    et al.
    Yli, B.
    Rasmussen, S.
    Norèn, H.
    Amer-Wåhlin, I.
    Didrik Saugstad, O.
    Stray-Pedersen, B.
    Rosén, Karl Gustaf
    University of Borås, School of Engineering.
    A new tool for the validation of umbilical cord acid: base data2010In: British Journal of Obstetrics and Gynecology, ISSN 1470-0328, E-ISSN 1471-0528, Vol. 117, no 12, p. 1544-1552Article in journal (Refereed)
    Abstract [en]

    Objective To identify the distribution of carbon dioxide tension (pCO2) relative to pH in validated umbilical cord acid–base data. Design Observational study. Setting European hospital labour wards. Population Data for 36 432 term newborns were obtained from three sources: two trials of fetal monitoring with electrocardiography (ECG; the Swedish randomised controlled trial and the European Union Fetal ECG trial) and data from Mölndal Hospital. Methods From the total study population, cases with missing values or obvious typing errors were excluded. The remaining data were validated based on specified criteria. Percentiles of arterial pCO2 by pH were calculated using multilevel regression modelling. Main outcome measures Umbilical cord pH, pCO2 and base deficit. Results Acid–base values were considered invalid in one out of seven cases. Percentiles for arterial pCO2 corresponding to specified values of arterial pH were developed from the validated data of 26 690 cases. Conclusions Percentiles for arterial pCO2 for a specified arterial pH can be used as a tool to identify cases with erroneously low pCO2 values, and thus avoid an incorrect interpretation of the newborn’s acid–base status.

  • 15.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Care@Distance: Hemövervakning av hjärtsviktpatienter2007Conference paper (Other academic)
  • 16.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Från projekt till klinisk rutin: när blir det så?2007Other (Other academic)
  • 17.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Välrenommerad medicinteknik från Borås2009In: Vetenskap för profession, ISSN 1654-6520, p. 27-35Article in journal (Other academic)
  • 18. Löfgren, Nils A.
    et al.
    Outram, Nicholas
    Thordstein, Magnus
    University of Borås, School of Engineering.
    EEG Entropy Estimation Using a Markov Model of the EEG for Sleep Stage Separation in Human Neonates2007In: Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, Kohala Coast, Hawaii, USA, May 2-5, 2007, IEEE , 2007Conference paper (Refereed)
  • 19. Löfgren, Nils
    et al.
    Thordstein, Magnus
    Löfhede, Johan
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Kjellmer, Ingemar
    Dean, Justin
    Mallard, Carina
    Slowly Altering Electrical Potentials over the Head During Hypoxia and LPS Exposure2007Conference paper (Refereed)
  • 20.
    Löfhede, Johan
    University of Borås, School of Engineering.
    Classification of Burst and Suppression in the Neonatal EEG2007Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The brain requires a continuous supply of oxygen and even a short period of reduced oxygen supply risks severe and lifelong consequences for the affected individual. The delivery is a vulnerable period for a baby who may experience for example hypoxia (lack of oxygen) that can damage the brain. Babies who experience problems are placed in an intensive care unit where their vital signs are monitored, but there is no reliable way to monitor the brain directly. Monitoring the brain would provide valuable information about the processes going on in it and could influence the treatment and help to improve the quality of neonatal care. The scope of this project is to develop methods that eventually can be put together to form a monitoring system for the brain that can function as decision-support for the physician in charge of treating the patient. The specific technical problem that is the topic of this thesis is detection of burst and suppression in the electroencephalogram (EEG) signal. The thesis starts with a brief description of the brain, with a focus on where the EEG originates, what types of activity can be found in this signal and what they mean. The data that have been available for the project are described, followed by the signal processing methods that have been used for preprocessing, and the feature functions that can be used for extracting certain types of characteristics from the data are defined. The next section describes classification methodology and how it can be used for making decisions based on combinations of several features extracted from a signal. The classification methods Fisher’s Linear Discriminant, Neural Networks and Support Vector Machines are described and are finally compared with respect to their ability to discriminate between burst and suppression. An experiment with different combinations of features in the classification has also been carried out. The results show similar results for the three methods but it can be seen that the SVM is the best method with respect to handling multiple features.

  • 21.
    Löfhede, Johan
    University of Borås, School of Engineering.
    The EEG of the neonatal brain: classification of background activity2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The brain requires a continuous supply of oxygen and nutrients, and even a short period of reduced oxygen supply can cause severe and lifelong consequences for the affected individual. The unborn baby is fairly robust, but there are of course limits also for these individuals. The most sensitive and most important organ is the brain. When the brain is deprived of oxygen, a process can start that ultimately may lead to the death of brain cells and irreparable brain damage. This process has two phases; one more or less immediate and one delayed. There is a window of time of up to 24 hours where action can be taken to prevent the delayed secondary damage. One recently clinically available technique is to reduce the metabolism and thereby stop the secondary damage in the brain by cooling the baby. It is important to be able to quickly diagnose hypoxic injuries and to follow the development of the processes in the brain. For this, the electroencephalogram (EEG) is an important tool. The EEG is a voltage signal that originates within the brain and that can be recorded easily and non-invasively at bedside. The signals are, however, highly complex and require special competence to interpret, a competence that typically is not available at the intensive care unit, and particularly not continuously day and night. This thesis addresses the problem of automatic classification of neonatal EEG and proposes methods that would be possible to use in bedside monitoring equipment for neonatal intensive care units. The thesis is a compilation of six papers. The first four deal with the segmentation of pathological signals (burst suppression) from post-asphyctic full term newborn babies. These studies investigate the use of various classification techniques, using both supervised and unsupervised learning. In paper V the scope is widened to include both classification of pathological activity versus activity found in healthy babies as well as application of the segmentation methods on the parts of the EEG signal that are found to be of the pathological type. The use of genetic algorithms for feature selection is also investigated. In paper VI the segmentation methods are applied on signals from pre-term babies to investigate the impact of a certain medication on the brain. The results of this thesis demonstrate ways to improve the monitoring of the brain during intensive care of newborn babies. Hopefully it will someday be implemented in monitoring equipment and help to prevent permanent brain damage in post asphyctic babies.

  • 22.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Degerman, Johan
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparing a Supervised and an Unsupervised Classification Method for Burst Detection in Neonatal EEG2008In: Proceedings of Engineering in Medicine and Biology Society, EMBS 2008. 30th Annual International Conference of the IEEE, 20-24 August, 2008, IEEE , 2008, p. 3836-3839Conference paper (Refereed)
    Abstract [en]

    Hidden Markov Models (HMM) and Support Vector Machines (SVM) using unsupervised and supervised training, respectively, were compared with respect to their ability to correctly classify burst and suppression in neonatal EEG. Each classifier was fed five feature signals extracted from EEG signals from six full term infants who had suffered from perinatal asphyxia. Visual inspection of the EEG by an experienced electroencephalographer was used as the gold standard when training the SVM, and for evaluating the performance of both methods. The results are presented as receiver operating characteristic (ROC) curves and quantified by the area under the curve (AUC). Our study show that the SVM and the HMM exhibit similar performance, despite their fundamental differences.

  • 23.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, A.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classifying Neonatal EEG2007Conference paper (Refereed)
  • 24.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, A.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparison of Three Methods for Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns2007In: Proceedings of the 29th Annual International Conference of the IEEE EMBS, Cité Internationale, Lyon, France, August 23-26, 2007, IEEE , 2007Conference paper (Refereed)
  • 25.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, N.
    Thordstein, M.
    Flisberg, I.
    Kjellmer, I.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns Using a Support Vector Machine2007In: Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, Kohala Coast, Hawaii, USA, May 2-5, 2007, IEEE , 2007Conference paper (Refereed)
  • 26.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classification of burst and suppression in the neonatal electroencephalogram2008In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 5, no 4, p. 402-410Article in journal (Refereed)
    Abstract [en]

    Fisher's linear discriminant (FLD), a feed-forward artificial neural network (ANN) and a support vector machine (SVM) were compared with respect to their ability to distinguish bursts from suppressions in electroencephalograms (EEG) displaying a burst-suppression pattern. Five features extracted from the EEG were used as inputs. The study was based on EEG signals from six full-term infants who had suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as the area under the curve (AUC), derived from receiver operating characteristic (ROC) curves for the three methods. Based on this, the SVM performs slightly better than the others. Testing the three methods with combinations of increasing numbers of the five features shows that the SVM handles the increasing amount of information better than the other methods.

  • 27.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Löfgren, Nils
    Thordstein, Magnus
    Flisberg, Anders
    Kjellmer, Ingmar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Classification of Burst Suppression and Tracé Alternant in Neonatal EEG2008In: Proceedings of Medicinteknikdagarna 2008. Annual conference of Svensk Förening för Medicinsk Teknik och Fysik, Göteborg, Oct., 2008, 2008Conference paper (Refereed)
  • 28.
    Löfhede, Johan
    et al.
    University of Borås, School of Engineering.
    Thordstein, Magnus
    Löfgren, Nils
    Flisberg, Anders
    Rosa-Zurera, Manuel
    Kjellmer, Ingemar
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Automatic classification of background EEG activity in healthy and sick neonates2010In: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 7, no 1Article in journal (Refereed)
    Abstract [en]

    The overall aim of our research is to develop methods for a monitoring system to be used at neonatal intensive care units. When monitoring a baby, a range of different types of background activity needs to be considered. In this work, we have developed a scheme for automatic classification of background EEG activity in newborn babies. EEG from six full-term babies who were displaying a burst suppression pattern while suffering from the after-effects of asphyxia during birth was included along with EEG from 20 full-term healthy newborn babies. The signals from the healthy babies were divided into four behavioural states: active awake, quiet awake, active sleep and quiet sleep. By using a number of features extracted from the EEG together with Fisher’s linear discriminant classifier we have managed to achieve 100% correct classification when separating burst suppression EEG from all four healthy EEG types and 93% true positive classification when separating quiet sleep from the other types. The other three sleep stages could not be classified. When the pathological burst suppression pattern was detected, the analysis was taken one step further and the signal was segmented into burst and suppression, allowing clinically relevant parameters such as suppression length and burst suppression ratio to be calculated. The segmentation of the burst suppression EEG works well, with a probability of error around 4%.

  • 29. Macias, Raul
    et al.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Bragos, Ramon
    Performance of the Load-in-the-Loop Single Op-Amp Voltage Controlled Current Source from the Op-Amp Parameters2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    In recent years, Electrical Bioimpedance (EBI) methods have gained importance. These methods are often based on obtaining impedance spectrum in the range of β-dispersion, i.e. from a few kHz up to some MHz. To measure EBI a constant current is often injected and the voltage across the tissue under study (TUS) is recorded. Due to the performance of the current source influences the performance of the entire system, in terms of frequency range, several designs have been implemented and studied. In this paper the basic structure of a Voltage-Controlled Current Source (VCCS) based on a single Op-Amp in inverter configuration with a floating load, known as load-in-the-loop current source, is revisited and studied deeply. We focus on the dependence of the output impedance with the circuit parameters, i.e. the feedback resistor and the inverter-input resistor, and the Op-Amp main parameters, i.e. open loop gain, CMRR and input impedance. After obtaining the experimental results and comparing to the theoretical and simulated ones, they confirm the design under study can be a good solution for multi-frequency wideband EBI applications because of higher values of the output impedance than 100kΩ at 1MHz are obtained. Furthermore, an enhancement of the basic design, using a current conveyor as a first stage, is proposed, studied and implemented.

  • 30.
    Marquez, Juan Carlos
    University of Borås, School of Engineering.
    On the Feasibility of Using Textile Electrodes for Electrical Bioimpedance Measurements2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The application of textile electrodes has been widely studied for biopotential recordings, especially for monitoring cardiac activity. Commercially available applications, such as the Adistar T-shirt and the Numetrex Cardioshirt, have shown good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for electrical bioimpedance (EBI) spectroscopy measurements in home and personalized health monitoring applications, however solid basic research about the measurement performance of the electrodes must be performed prior to the development of any textile-enabled EBI application. This research work studies the performance of EBI spectroscopy measurements when performed with textile electrodes. An analysis using an electrical circuit equivalent model and experimental data obtained with the Impedimed spectrometer SFB7 was carried out. The experimental study focused on EBI spectroscopy measurements obtained with different types of textile electrodes and in different measurement scenarios. The equivalent model analysis focused on the influence of the electrode polarization impedance Zep on the EBI spectroscopy measurements in the frequency range of 3 kHz to 500 kHz. The analysis of the obtained complex EBI spectra shows that the measurements obtained with textile electrodes produce constant and reliable EBI spectra. The results also indicate the importance of the skin-electrode interface in EBI spectroscopy measurement. Textile technology, if successfully integrated, may enable the performance of EBI spectroscopy measurements in new scenarios, which would allow the generation of novel, wearable, or textile-enabled applications for home and personal health monitoring

  • 31.
    Marquez, Juan Carlos
    et al.
    University of Borås, School of Engineering.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Välimaki, Elina
    University of Borås, Swedish School of Textiles.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Comparison of Dry-textile Electrodes for Electrical Bioimpedance Spectroscopy Measurements.2010In: Journal of Physics: Conference Series, Institute of Physics Publishing Ltd. , 2010Conference paper (Refereed)
    Abstract [en]

    Electrodes have been widely studied for biopotentials recordings, specially for monitoring the cardiac activity. Commercially available applications, such as Adistar T-shirt and Textronics Cardioshirt, have proved a good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for Electrical Bioimpedance Spectroscopy measurements enabling home and personalized health monitoring applications however solid ground research about the measurement performance of the electrodes must be done prior to the development of any textile-enabled EBI application. In this work a comparison of the measurement performance of two different types of dry-textile electrodes and manufacturers has been performed against standardized RedDot 3M Ag/AgCl electrolytic electrodes. 4-Electrode, whole body, Ankle-to-Wrist EBI measurements have been taken with the Impedimed spectrometer SFB7 from healthy subjects in the frequency range of 3kHz to 500kHz. Measurements have been taken with dry electrodes at different times to study the influence of the interaction skin-electrode interface on the EBI measurements. The analysis of the obtained complex EBI spectra shows that the measurements performed with textile electrodes produce constant and reliable EBI spectra. Certain deviation can be observed at higher frequencies and the measurements obtained with Textronics and Ag/AgCl electrodes present a better resemblance. Textile technology, if successfully integrated it, may enable the performance of EBI measurements in new scenarios allowing the rising of novel wearable monitoring applications for home and personal care as well as car safety

  • 32.
    Seoane, Fernando
    University of Borås, School of Engineering.
    Current Source for Multifrequency Broadband Electrial Bioimpedance Spectroscopy Systems. A Novel Approach.2006Conference paper (Refereed)
  • 33.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramon
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Current Source for Wideband Multifrequency Electrical Bioimpedance Measurements2006In: IEEE Transactions on Biomedical Circuits and Systems, ISSN 1932-4545, E-ISSN 1940-9990, p. 5121-5125Article in journal (Other academic)
  • 34.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramon
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Riu, Pere J.
    Current Source Design for Electrical Bioimpedance Spectroscopy2008In: Encyclopaedia of Healthcare Information Systems, Encyclopaedia of Healthcare Information Systems , 2008Chapter in book (Other academic)
  • 35.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Bragós, Ramón
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Current Source for Wideband Electrical Bioimpedance Spectroscopy Based on a Single Operational Amplifier.2006Conference paper (Refereed)
    Abstract [en]

    Traditionally, measurements of electrical bioimpedance for medical diagnostic purposes have used only low frequencies, usually below 100 kHz. The analysis focused only on the resistive part of the impedance; very often at low frequencies the reactive part of the impedance is negligible. Recent studies of the electrical bioimpedance spectrum, both real and imaginary parts, have indicated new potential applications e.g. detection of meningitis, skin cancer assessment and brain cellular edema detection. An important functional unit in a wideband impedance spectrometer is the current source used to inject the current into the tissue under study. A current source must provide an output current virtually constant over the frequency range of interest and independent of the load at the output. Several designs have been proposed over the years but the performance of them all degraded markedly near bellow 1 MHz e.g. Ackmann in 1993, Bragos et al in 1994 and Bertemes-Filho et al in 2000. The development of electronic technology has made available devices that allow us to obtain a current source with large output impedance, larger than 100 k Omega, above I MHz and based in a simple single Op-Amp circuit topology. Simulation results and experimental measurements are compared and the most important parameters of the VCCS are analytically studied and experimentally tested, including the dependency to changes in the circuit elements and the incidence of the Op-Amp parameters on the current source features.

  • 36.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Ferreira, Javier
    José Sanchéz, Juan
    Bragós, Ramon
    An Analog Front-End Enables Electrical Impedance Spectroscopy System On-Chip for Biomedical Applications2008In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 29, no 6Article in journal (Other academic)
    Abstract [en]

    The increasing number of applications of electrical bioimpedance measurement in biomedical application together with the continuous advances in the textile technology applied in the design and development of biopotential electrodes has encouraged several researchers to do the first attempts to develop portable electrical bioimpedance measurement systems and even wearable. The main aim of these systems is mainly home-monitoring. Analog Devices has provided us with the AD5933, a new system-on-chip fully integrated electrical impedance spectrometer which might allow the implementation of minimal size instrumentation for electrical bioimpedance measurements. This system, however, performs a 2-Electrode measurement and thus is not suitable for most of the spectroscopy applications of electrical bioimpedance. In this work we present a relatively simple analog front-end that adapts the AD5933 to a 4-Electrode strategy, allowing its use in biomedical applications. The resulting impedance measurements exhibit a better performance in aspects like load dynamic range and accuracy. These type of minimum-size, AD5933-based bioimpedance measurement systems would lead the researcher to develop and implement light and wearable electrical bioimpedance systems for monitoring applications, a new a huge niche for medical technology development

  • 37.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Ferreira, Javier
    University of Borås, School of Engineering.
    Marquez, Juan Carlos
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Conductive Polymer Films as Textrodes for Biopotential Sensing2011Conference paper (Other academic)
    Abstract [en]

    Introduction: After several years of progresses in textile technology and wearable measurement instrumentation, applications of wearable textile-electronics systems are arising providing a stable background for commercial applications. So far, the available commercial solutions are centered on fitness applications and mostly based in the acquisition of heart rate through Textile Electrodes (Textrodes) based on metallic threads or on conductive rubber compounds. Methods and Materials: In this work a novel material approach is presented to produce Textrodes for acquisition of Electrocardiographic (ECG) signals using a conductive polypropylene (PP1386 from Premix, Finland) polymer material. The polymer was film extruded into thin films, and used as such in the Textrode. Conductive Polymer Films (CPF) have been used to produce Textrodes, and its measurement performance has been compared with the ECG signals obtained with commercial Textrode fabrics and conventional Ag/AgCl electrodes. In order to set up the same measurement conditions, a chest strap tailored to host the testing electrodes has been used. Results: The close resemblance of the ECG acquired with the textile fabric electrodes, the Ag/AgCl electrodes and the PP1386 CPF electrodes suggest that the Polymer Electrodes PP1386 are a feasible alternative to the current textile fabrics that use silver thread as conductive material and also to conductive rubber material. Discussion & Conclusion: The availability of the Conductive Polymer Electrode PP1386 in a film form allows the manufacturing of electrodes by conventional textile processes, like lamination or sewing, therefore facilitating the transition from lab prototyping to industrial manufacturing. Replacing the traditional silver thread as conductive element in the fabrication of Textrodes will definitely reduce the material cost per Textrode. Biocompatibility issues and manufacturability issues must be addressed but the exhibited functional performance is showing encouraging results.

  • 38.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    A Novel Approach for Estimation of Electrical Bioimpedance: Total Least Square.2007Conference paper (Other academic)
  • 39.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Electrial Bioimpedance Cerebral Monitoring2008In: Encyclopaedia of Healthcare Information Systems, Encyclopaedia of Healthcare Information Systems. , 2008Chapter in book (Other academic)
  • 40.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lu, Mai
    Persson, Mikael
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Electrical Bioimpedance Cerebral Monitoring. A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model2007In: Proceedings of the 3rd International IEEE EMBS Conference on Neural Engineering, IEEE , 2007Conference paper (Refereed)
    Abstract [en]

    There have been several studies of the application of electrical bioimpedance technology for brain monitoring in the past years. They have targeted a variety of events and injuries e.g. epilepsy or stroke. The current density distribution and the voltage lead field associated with an impedance measurement setup is of critical importance for the proper analysis of any dynamics in the impedance measurement or for an accurate reconstruction of an EIT image, specially a dynamic type. In this work for the first time, the current density distribution is calculated in a human head with anatomical accuracy and resolution down to 1 mm, containing up to 24 tissues and considering the frequency dependency of the conductivity of each tissue. The obtained current densities and the subsequent sensitivity maps are analyzed with a special focus on the dependency of the electrode arrangement and also the measurement frequency. The obtained results provide us with interesting and relevant information to consider in the design of any tool for electrical bioimpedance cerebral monitoring.

  • 41.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Lu, Mai
    Persson, Mikael
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    The Role of the Cerebrospinal Fluid in the Distribution of Electrical Current within the Brain and its Implications for Electrical Bioimpedance Cerebral Monitoring.2007Conference paper (Refereed)
  • 42.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Mohino-Herranz, Inmaculada
    Ferreira González, Javier
    University of Borås, School of Engineering.
    Alvarez, Lorena
    Buendia, Ruben
    Ayllón, David
    Cosme, Llerena
    Gil-Pita, Roberto
    Wearable Biomedical Measurement Systems for Assessment of Mental Stress of Combatants in Real Time2014In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 4, p. 7120-7141Article in journal (Refereed)
    Abstract [en]

    The Spanish Ministry of Defense, through its Future Combatant program, has sought to develop technology aids with the aim of extending combatants' operational capabilities. Within this framework the ATREC project funded by the “Coincidente” program aims at analyzing diverse biometrics to assess by real time monitoring the stress levels of combatants. This project combines multidisciplinary disciplines and fields, including wearable instrumentation, textile technology, signal processing, pattern recognition and psychological analysis of the obtained information. In this work the ATREC project is described, including the different execution phases, the wearable biomedical measurement systems, the experimental setup, the biomedical signal analysis and speech processing performed. The preliminary results obtained from the data analysis collected during the first phase of the project are presented, indicating the good classification performance exhibited when using features obtained from electrocardiographic recordings and electrical bioimpedance measurements from the thorax. These results suggest that cardiac and respiration activity offer better biomarkers for assessment of stress than speech, galvanic skin response or skin temperature when recorded with wearable biomedical measurement systems.

  • 43.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Rempfler, Markus
    Marquez, Juan Carlos
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Textile-enabled Instrumentation for Impedance Cardiographic Signals2011Conference paper (Other academic)
    Abstract [en]

    Research efforts in the areas of Electrical Bioimpedance (EBI) and textile materials with conductive properties have contributed to the proliferation of research projects aiming to test the feasibility of implementing Textile-enabled instrumentation for performing EBI measurements. Most of the work done has been focused on the electrical characterization of the Textrodes (textile electrodes) and on spectroscopy applications of EBI like early detection of Cardiogenic Pulmonary Edema. In this work, a garment composed of two belts containing Textrodes made of conductive Velcro, loops-type, has been manufactured. Both, the abdomen and the neck belts, have four Textrodes connected through a conductive fabric Technik Tex P-130+ Shieldex fabric in pairs. This way, a tetrapolar EBI measurement between the neck and the chest is performed, implementing a typical band electrode arrangement [1] approach with the two belts. Using a custom-made device Respimon that measures the electrical cardiac activity with a 1-lead ECG and a tetrapolar EBI measurement at 50kHz of a portion of the body, and the Textrode garment, the ICG and ECG signals have been recorded and compared with the recordings obtained with Ag/AgCl electrodes placed in the same positions. The resemblance of the ICG and ECG signals obtained with both the Ag/AgCl electrodes and the Textrode garment confirms the feasibility of using Textrodes to perform measurements of cardiac impedance. There are several useful hemodynamic parameters that can be extracted from the ICG signal in combination with the ECG signal. The availability of a Textrode garment, easy to wear and that produces reliable ICG measurements, would contribute to present ICG monitoring as feasible technology for implementing personalized healthcare monitoring systems, especially for e-health applications of heart failure patients management.

  • 44.
    Seoane, Fernando
    et al.
    University of Borås, School of Engineering.
    Valero, M.A.
    García-Perez, A.
    Gallar, P.
    Implementation of an Open Telenephrology Platform to Support Home Monitoring2008Conference paper (Refereed)
  • 45. Thordstein, Magnus
    et al.
    Flisberg, Anders
    Inganäs, L.
    Mourtzis, A.
    Karlsson, L.
    Rex, K.
    Löfhede, Johan
    University of Borås, School of Engineering.
    Löfgren, Nils
    Förbättrad användning av aEEG för övervakning av centralnervös funktion hos nyfödda barn. En prospektiv, populationsbaserad studie.2008In: Proceedings of Medicinteknikdagarna 2008, 2008Conference paper (Refereed)
  • 46. Thordstein, Magnus
    et al.
    Kjellmer, Ingemar
    Löfgren, Nils
    Löfhede, Johan
    University of Borås, School of Engineering.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Dean, Justin
    Mallard, Carina
    Effects of inflammation on cerebral electric activity in fetal sheep2008Conference paper (Other academic)
    Abstract [en]

    OBJECTIVE Intrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2. Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain. METHODS Fetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.). RESULTS Exposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG. CONCLUSIONS These recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.

  • 47. Wiklund, Urban
    et al.
    Karlsson, Marcus
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Eriksson, Siw
    University of Borås, Swedish School of Textiles.
    Guo, Li
    University of Borås, Swedish School of Textiles.
    Bäcklund, Tomas
    Sandsjö, Leif
    University of Borås, School of Engineering.
    Rytm och formanalys av EKG från textila sensorer2010Conference paper (Other academic)
  • 48. Wiklund, Urban
    et al.
    Karlsson, Marcus
    Östlund, Nils
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Lindecrantz, Kaj
    University of Borås, School of Engineering.
    Karlsson, Stefan
    Sandsjö, Leif
    University of Borås, School of Engineering.
    Adaptive spatio-temporal filtering of disturbed ECGs: a multi-channel approach to heartbeat detection in smart clothing2007In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 45, no 6Article in journal (Refereed)
1 - 48 of 48
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf