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  • 1.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Aspects of Electrical Bioimpedance Spectrum Estimation2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Electrical bioimpedance spectroscopy (EBIS) has been used to assess the status or composition of various types of tissue, and examples of EBIS include body composition analysis (BCA) and tissue characterisation for skin cancer detection. EBIS is a non-invasive method that has the potential to provide a large amount of information for diagnosis or monitoring purposes, such as the monitoring of pulmonary oedema, i.e., fluid accumulation in the lungs. However, in many cases, systems based on EBIS have not become generally accepted in clinical practice. Possible reasons behind the low acceptance of EBIS could involve inaccurate models; artefacts, such as those from movements; measurement errors; and estimation errors. Previous thoracic EBIS measurements aimed at pulmonary oedema have shown some uncertainties in their results, making it difficult to produce trustworthy monitoring methods. The current research hypothesis was that these uncertainties mostly originate from estimation errors. In particular, time-varying behaviours of the thorax, e.g., respiratory and cardiac activity, can cause estimation errors, which make it tricky to detect the slowly varying behaviour of this system, i.e., pulmonary oedema.

    The aim of this thesis is to investigate potential sources of estimation error in transthoracic impedance spectroscopy (TIS) for pulmonary oedema detection and to propose methods to prevent or compensate for these errors.   This work is mainly focused on two aspects of impedance spectrum estimation: first, the problems associated with the delay between estimations of spectrum samples in the frequency-sweep technique and second, the influence of undersampling (a result of impedance estimation times) when estimating an EBIS spectrum. The delay between frequency sweeps can produce huge errors when analysing EBIS spectra, but its effect decreases with averaging or low-pass filtering, which is a common and simple method for monitoring the time-invariant behaviour of a system. The results show the importance of the undersampling effect as the main estimation error that can cause uncertainty in TIS measurements.  The best time for dealing with this error is during the design process, when the system can be designed to avoid this error or with the possibility to compensate for the error during analysis. A case study of monitoring pulmonary oedema is used to assess the effect of these two estimation errors. However, the results can be generalised to any case for identifying the slowly varying behaviour of physiological systems that also display higher frequency variations.  Finally, some suggestions for designing an EBIS measurement system and analysis methods to avoid or compensate for these estimation errors are discussed.

  • 2.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Towards Heart Rate Variability Tools in P-Health: Pervasive, Preventive, Predictive and Personalized2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Hjärtfrekvensvariabilitet (HRV) har senaste tiden rönt en hel del uppmärksamhet och flera teknikerför analys av HRV i tids- resp. frekvensområdet samt medels icke-linjära metoder har utvecklats.Det har visats att HRV kan användas för att övervaka det autonoma nervsystemet (ANS) blandannat för att upptäcka särskilt vagala störningar inom ANS. Minskad HRV förknippas med flerasjukdomar såsom diabetes, reumatoid artrit, depression, kronisk hjärtsjukdom och har ävenföreslagits som prediktor för dålig prognos och plötslig hjärtdöd. HRV är dock ännu inte allmäntaccepterat som ett kliniskt verktyg utan används främst inom forskning. Framsteg inomneuroimmunitetsområdet med ökad förståelse för sambandet mellan nerv- och immunsystem, haröppnat en nytt potentiell område för HRV-applikationer. Ett exempel är när systemiskinflammationoch autoimmun sjukdom primärt orsakas av låg vagal aktivitet, vilket kan upptäckas ochprognostiseras via minskad HRV. Denna avhandling är resultatet av flera tekniska utvecklingsstegoch explorativ forskning där HRV tillämpas i syfte att utveckla ett prognostiskt diagnostiskt verktygmed förebyggande potential. Huvudsyften har varit: 1) att utveckla ett prisvärt verktyg för eneffektiv och enkel analys av HRV 2) att studera sambandet mellan HRV och pro-inflammatoriskamarkörer och därigenom potentiellt återspegla graden av aktivitet i den kolinergaantiinflammatoriska effektorvägen 3) att utveckla datorprogramvara för ett biologisktåterkopplingssystem där individen med egen träning ökar sin vagala aktivitet vilket sedanåterspeglas i en ökad HRV. I denna sammanläggningsavhandling finns utförlig beskrivning av varjeingående studies metod och resultat artikar I-VI. I ramberättelsen presenteras en kortsammanfattning av metoder och resultat, grupperade efter ämne och sammanhang.Sammanfattningsvis visar resultaten att de utvecklade verktygen adekvat registrerar och analyserarHRV korrekt enkelt , samt att HRV kan påverkas av spel-träning. HRV i framtaget koncept harpotential att användas som ett skarpt prognostiskt verktyg, inte bara för traditionell vård med fokuspå sjukdom, utan också inom friskvård. Framtagna verktyg möjliggör tidig upptäckt av minskadHRV, snabb intervention och prevention. Spelifiering med seriöst spelande utgör en potentiellplattform som motiverar en träningsrutin och som genom återkoppling kan öka HRV och därmedvälmåendet.

  • 3.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Berndtsson, Andreas
    Abtahi, Shirin
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Development and preliminary evaluation of an Android based heart rate variability biofeedback system2014Ingår i: Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE, IEEE conference proceedings, 2014, s. 3382-3385Konferensbidrag (Refereegranskat)
    Abstract [en]

    The reduced Heart Rate Variability (HRV) is believed to be associated with several diseases such as congestive heart failure, diabetes and chronic kidney diseases (CKD). In these cases, HRV biofeedback may be a potential intervention method to increase HRV which in turn is beneficial to these patients. In this work, a real-time Android biofeedback application based on a Bluetooth enabled ECG and thoracic electrical bioimpedance (respiration) measurement device has been developed. The system performance and usability have been evaluated in a brief study with eight healthy volunteers. The result demonstrates real-time performance of system and positive effects of biofeedback training session by increased HRV and reduced heart rate. Further development of the application and training protocol is ongoing to investigate duration of training session to find an optimum length and interval of biofeedback sessions to use in potential interventions.

  • 4. Abtahi, Farhad
    et al.
    Forsman, Mikael
    Diaz-Olivazrez, Jose A.
    KTH, Skolan för teknik och hälsa (STH).
    Yang, Liyun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH).
    Eklund, Jörgen
    KTH, Skolan för teknik och hälsa (STH).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH).
    Seoane, Fernando
    Teriö, Heikki
    Mediavilla Martinez, Cesar
    Aso, Santiago
    Tiemann, Christian
    Big Data & Wearable Sensors Ensuring Safety and Health @Work2017Ingår i: GLOBAL HEALTH 2017, The Sixth International Conference on Global Health Challenges, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    —Work-related injuries and disorders constitute a major burden and cost for employers, society in general and workers in particular. We@Work is a project that aims to develop an integrated solution for promoting and supporting a safe and healthy working life by combining wearable technologies, Big Data analytics, ergonomics, and information and communication technologies. The We@Work solution aims to support the worker and employer to ensure a healthy working life through pervasive monitoring for early warnings, prompt detection of capacity-loss and accurate risk assessments at workplace as well as self-management of a healthy working life. A multiservice platform will allow unobtrusive data collection at workplaces. Big Data analytics will provide real-time information useful to prevent work injuries and support healthy working life

  • 5.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Patientsäkerhet (Stängd 20130701).
    Gyllensten, Illapha Cuba
    KTH, Skolan för teknik och hälsa (STH).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Software tool for analysis of breathing-related errors in transthoracic electrical bioimpedance spectroscopy measurements2012Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 407, nr 1, s. 012028-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied in a range of different applications and mainly using the frequency sweep-technique. Traditionally the tissue under study is considered to be timeinvariant and dynamic changes of tissue activity are ignored and instead treated as a noise source. This assumption has not been adequately tested and could have a negative impact and limit the accuracy for impedance monitoring systems. In order to successfully use frequency-sweeping EBIS for monitoring time-variant systems, it is paramount to study the effect of frequency-sweep delay on Cole Model-based analysis. In this work, we present a software tool that can be used to simulate the influence of respiration activity in frequency-sweep EBIS measurements of the human thorax and analyse the effects of the different error sources. Preliminary results indicate that the deviation on the EBIS measurement might be significant at any frequency, and especially in the impedance plane. Therefore the impact on Cole-model analysis might be different depending on method applied for Cole parameter estimation.

  • 6.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institutet, Sweden.
    Hilderman, Marie
    Bruchfeld, Annette
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Borås, Sweden.
    Janerot-Sjöberg, Birgitta
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik. Karolinska Institutet, Sweden.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institutet, Sweden.
    Pro-inflammatory Blood Markers and Heart Rate Variability in Apnoea as a Reflection of Basal Vagal ToneManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Pro-inflammatory cytokines play a crucial role in inflammatory response, which istightly regulated by the nervous system to avoid the damage caused by inflammation. There isevidence for a cholinergic anti-inflammatory pathway that includes afferent and efferent vagalnerves that sense the inflammation and stimulate the anti-inflammatory response. Non-functionalanti-inflammatory response might lead to excessive and chronic inflammation e.g., rheumatoidarthritis (RA), inflammatory bowel disease (IBD), and poor outcome. Heart rate variability(HRV) has been proposed as a potential tool to monitor the level of anti-inflammatory activitythrough the monitoring of vagal activity. In this paper, the association of pro-inflammatorymarkers with HRV indices is evaluated. We used a database called “Heart Biomarker Evaluationin Apnea Treatment (HeartBEAT)” that consists of 6±2 hours of Electrocardiogram (ECG)recordings during nocturnal sleep from 318 patients at baseline and 301of them at 3 monthsfollow-up. HRV indices are calculated from ECG recordings of 5-360 minutes. The results showa statistically significant correlation between heart rate (HR) and pro-inflammatory cytokines,independent of duration of ECG analysis. HRV indices e.g., standard deviation of all RRintervals (SDNN) show an inverse relation to the pro-inflammatory cytokines. Longer ECGrecordings show a higher potential to reflect the level of anti-inflammatory response. In light oftheories for the cholinergic anti-inflammatory pathway, a combination of HR and HRV as areflection of basal vagal activity might be a potential prognostic tool for interventional guidance.

  • 7.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Ji, Guangchao
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rodby, Kristian
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    A knitted garment using intarsia technique for Heart Rate Variability biofeedback: Evaluation of initial prototype2015Ingår i: Engineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE, IEEE , 2015, Vol. 2015, s. 3121-3124Konferensbidrag (Refereegranskat)
    Abstract [en]

    Heart rate variability (HRV) biofeedback is a method based on paced breathing at specific rate called resonance frequency by giving online feedbacks from user respiration and its effect on HRV. Since the HRV is also influence by different factors like stress and emotions, stress related to an unfamiliar measurement device, cables and skin electrodes may cover the underling effect of such kind of intervention. Wearable systems are usually considered as intuitive solutions which are more familiar to the end-user and can help to improve usability and hence reducing the stress. In this work, a prototype of a knitted garment using intarsia technique is developed and evaluated. Results show the satisfactory level of quality for Electrocardiogram and thoracic electrical bioimpedance i.e. for respiration monitoring as a part of HRV biofeedback system. Using intarsia technique and conductive yarn for making the connection instead of cables will reduce the complexity of fabrication in textile production and hence reduce the final costs in a final commercial product. Further development of garment and Android application is ongoing and usability and efficiency of final prototype will be evaluated in detail.

  • 8.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Ji, Guangchao
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Konferensbidrag (Övrigt vetenskapligt)
  • 9.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Aslamy, Benjamin
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Boujabir, Imaneh
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    An Affordable ECG and Respiration Monitoring System Based on Raspberry PI and ADAS1000: First Step towards Homecare Applications2015Ingår i: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden, Springer, 2015, s. 5-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Homecare is a potential solution for problems associated with an aging population. This may involve several physiological measurements, and hence a flexible but affordable measurement device is needed. In this work, we have designed an ADAS1000-based four-lead electrocardiogram (ECG) and respiration monitoring system. It has been implemented using Raspberry PI as a platform for homecare applications. ADuM chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 and IEC 60950 for patient safety. The result proved the potential of Raspberry PI for the design of a compact, affordable, and medically safe measurement device. Further work involves developing a more flexible software for collecting measurements from different devices (measuring, e.g., blood pressure, weight, impedance spectroscopy, blood glucose) through Bluetooth or user input and integrating them into a cloud-based homecare system.

  • 10.
    Abtahi, Farhad
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Karolinska Inst, Inst Environm Med, S-17165 Stockholm, Sweden..
    Lu, Ke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Diaz-Olivares, Jose A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Forsman, Mikael
    Karolinska Inst, Inst Environm Med, S-17165 Stockholm, Sweden..
    Seoane, Fernando
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Halsovagen 7, S-14157 Stockholm, Sweden.;Univ Boras, Swedish Sch Text, Allegatan 1, S-50190 Boras, Sweden.;Karolinska Univ Hosp, Dept Biomed Engn, S-17176 Solna, Sweden..
    Lindecrantz, Kaj
    Karolinska Inst, Inst Environm Med, S-17165 Stockholm, Sweden.;Univ Boras, Sci Pk,Allegatan 1, S-50190 Boras, Sweden..
    Wearable Sensors Enabling Personalized Occupational Healthcare2018Ingår i: INTELLIGENT ENVIRONMENTS 2018 / [ed] Chatzigiannakis, I Tobe, Y Novais, P Amft, O, IOS PRESS , 2018, s. 371-376Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents needs and potentials for wearable sensors in occupational healthcare. In addition, it presents ongoing European and Swedish projects for developing personalized, and pervasive wearable systems for assessing risks of developing musculoskeletal disorders and cardiovascular diseases at work. Occupational healthcare should benefit in preventing diseases and disorders by providing the right feedback at the right time to the right person. Collected data from workers can provide evidence supporting the ergonomic and industrial tasks of redesigning the working environment to reduce the risks.

  • 11.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Dizon, M
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Johansson, M
    KTH-School of Technology and Health.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Evaluating Atrial Fibrillation Detection Algorithm based on Heart Rate Variability analysis2015Ingår i: Medicinteknikdagarna, Uppsala: Svensk förening för medicinsk teknik och fysik , 2015Konferensbidrag (Refereegranskat)
  • 12.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Dizon, M
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Johansson, M
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Evaluation of Atrial Fibrillation Detection by using Heart Rate Variability analysis2015Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Guangchao, Li
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås.
    A Knitted Garment using Intarsia Technique for Heart Rate Variability Biofeedback: Evaluation of Initial Prototype.2015Konferensbidrag (Övrigt vetenskapligt)
  • 14.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Electrical bioimpedance spectroscopy in time-variant systems: Is undersampling always a problem?2014Ingår i: Journal of Electrical Bioimpedance, ISSN 1891-5469, Vol. 5, nr 1, s. 28-33Artikel i tidskrift (Refereegranskat)
    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.

  • 15.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Löfgren, Nils
    Elimination of ECG Artefacts in Foetal EEG Using Ensemble Average Subtraction and Wavelet Denoising Methods: A Simulation2014Ingår i: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, s. 551-554Konferensbidrag (Refereegranskat)
    Abstract [en]

    Biological signals recorded from surface electrodes contain interference from other signals which are not desired and should be considered as noise. Heart activity is especially present in EEG and EMG recordings as a noise. In this work, two ECG elimination methods are implemented; ensemble average subtraction (EAS) and wavelet denoising methods. Comparison of these methods has been done by use of simulated signals achieved by adding ECG to neonates EEG. The result shows successful elimination of ECG artifacts by using both methods. In general EAS method which remove estimate of all ECG components from signal is more trustable but it is also harder for implementation due to sensitivity to noise. It is also concluded that EAS behaves like a high-pass filter while wavelet denoising method acts as low-pass filter and hence the choice of one method depends on application.

  • 16.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Snäll, Jonatan
    KTH, Skolan för teknik och hälsa (STH).
    Aslamy, Benjamin
    KTH, Skolan för teknik och hälsa (STH).
    Abtahi, Shirin
    KTH, Skolan för teknik och hälsa (STH).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Boras, Sweden.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institute, Sweden.
    Biosignal PI, an Affordable Open-Source ECG and Respiration Measurement System2014Ingår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, nr 1, s. 93-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioimedical pilot projects e.g., telemedicine, homecare, animal and human trials usually involve several physiological measurements. Technical development of these projects is time consuming and in particular costly. A versatile but affordable biosignal measurement platform can help to reduce time and risk while keeping the focus on the important goal and making an efficient use of resources. In this work, an affordable and open source platform for development of physiological signals is proposed. As a first step an 8–12 leads electrocardiogram (ECG) and respiration monitoring system is developed. Chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 for patient safety. The result shows the potential of this platform as a base for prototyping compact, affordable, and medically safe measurement systems. Further work involves both hardware and software development to develop modules. These modules may require development of front-ends for other biosignals or just collect data wirelessly from different devices e.g., blood pressure, weight, bioimpedance spectrum, blood glucose, e.g., through Bluetooth. All design and development documents, files and source codes will be available for non-commercial use through project website, BiosignalPI.org.

  • 17.
    Cuba-Gyllensten, Illapha
    et al.
    KTH, Skolan för teknik och hälsa (STH). Philips Research Europe, High Tech. Campus 34, 5656AE, Eindhoven, Netherlands; ACTLab., Signal Processing Systems, TU Eindhoven, 5600MB Eindhoven, Netherlands.
    Abtahi, Farhad
    Philips Research Europe, High Tech. Campus 34, 5656AE, Eindhoven, Netherlands.
    Bonomi, Alberto G.
    KTH, Skolan för teknik och hälsa (STH).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Borås, Sweden.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institute, Sweden.
    Amft, O.
    ACTLab., Signal Processing Systems, TU Eindhoven, 5600MB Eindhoven, Netherlands.
    Removing respiratory artefacts from transthoracic bioimpedance spectroscopy measurements2013Ingår i: XV International Conference on Electrical Bio-Impedance (ICEBI) & XIV Conference on Electrical Impedance Tomography (EIT), Institute of Physics Publishing (IOPP), 2013, Vol. 434, nr 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Transthoracic impedance spectroscopy (TIS) measurements from wearable textile electrodes provide a tool to remotely and non-invasively monitor patient health. However, breathing and cardiac processes inevitably affect TIS measurements, since they are sensitive to changes in geometry and air or fluid volumes in the thorax. This study aimed at investigating the effect of respiration on Cole parameters extracted from TIS measurements and developing a method to suppress artifacts. TIS data were collected from 10 participants at 16 frequencies (range: 10 kHz - 1 MHz) using a textile electrode system (Philips Technologie Gmbh). Simultaneously, breathing volumes and frequency were logged using an electronic spirometer augmented with data from a breathing belt. The effect of respiration on TIS measurements was studied at paced (10 and 16 bpm) deep and shallow breathing. These measurements were repeated for each subject in three different postures (lying down, reclining and sitting). Cole parameter estimation was improved by assessing the tidal expiration point thus removing breathing artifacts. This leads to lower intra-subject variability between sessions and a need for less measurements points to accurately assess the spectra. Future work should explore algorithmic artifacts compensation models using breathing and posture or patient contextual information to improve ambulatory transthoracic impedance measurements.

  • 18. Garcia-Molina, G.
    et al.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lagares-Lemos, M.
    Automated NREM sleep staging using the Electro-oculogram: A pilot study2012Ingår i: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, s. 2255-2258Konferensbidrag (Refereegranskat)
    Abstract [en]

    Automatic sleep staging from convenient and unobtrusive sensors has received considerable attention lately because this can enable a large range of potential applications in the clinical and consumer fields. In this paper the focus is on achieving non-REM (NREM) sleep staging from ocular electrodes. From these signals, specific patterns related to sleep such as slow eye movements, K-complexes, eye blinks, and spectral features are estimated. Although such patterns are characteristic of the Electroencephalogram, they can also be visible to a lesser extent on signals from ocular electrodes. Automatic sleep staging was implemented using two approaches: i) based on a state-machine and ii) using a neural network. The first one relied on the recommendations of the American Academy of Sleep Medicine, and the second one used a multilayer perceptron which was trained on manually sleep-staged data. Results were obtained on the data of five volunteers who participated in a nap experiment. Manual sleep staging of this data, performed by an expert, was used as reference. Five stages were considered, namely wake with eyes open, wake with eyes closed, and sleep stages N1, N2, and N3. The results were characterized in terms of confusion matrices from which the Cohen's κ coefficients were estimated. The values of κ for both the state-machine and neural-network based automatic sleep staging approaches were 0.79 and 0.59 respectively. Thus, the state-machine based approach shows a very good agreement with manual staging of sleep-data.

  • 19. Gyllencreutz, Erika
    et al.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Nordström, Lennart
    Lindqvist, Pelle
    Holzmann, Malin
    Characteristics of variable decelerations and prediction of fetal acidemia2017Ingår i: American Journal of Obstetrics and Gynecology, ISSN 0002-9378, E-ISSN 1097-6868, Vol. 216, nr 1, s. S507-S507Artikel i tidskrift (Övrigt vetenskapligt)
  • 20.
    Gyllencreutz, Erika
    et al.
    Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden.;Ostersund Hosp, Dept Obstet & Gynecol, S-83183 Region Jamtland Harjedal, Ostersund, Sweden..
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH). Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden..
    Lindqvist, Pelle G.
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden.;Karolinska Univ Hosp, Pregnancy & Delivery Care, Stockholm, Sweden..
    Nordström, Lennart
    Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden.;Karolinska Univ Hosp, Pregnancy & Delivery Care, Stockholm, Sweden..
    Holzmann, Malin
    Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden.;Karolinska Univ Hosp, Pregnancy & Delivery Care, Stockholm, Sweden..
    Abtahi, Farhad
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden.;Karolinska Univ Hosp Huddinge, Dept Clin Physiol, Stockholm, Sweden..
    Validation of a computerized algorithm to quantify fetal heart rate deceleration area2018Ingår i: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, Vol. 97, nr 9, s. 1137-1147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    IntroductionReliability in visual cardiotocography interpretation is unsatisfying, which has led to the development of computerized cardiotocography. Computerized analysis is well established for antenatal fetal surveillance but has yet not performed sufficiently during labor. We aimed to investigate the capacity of a new computerized algorithm compared with visual assessment in identifying intrapartum fetal heart rate baseline and decelerations. Material and methodsIn all, 312 intrapartum cardiotocography tracings with variable decelerations were analyzed by the computerized algorithm and visually examined by two observers, blinded to each other and the computer analysis. The width, depth and area of each deceleration was measured. Four cases (>100 variable decelerations) were subjected to in-depth detailed analysis. The outcome measures were bias in seconds (width), beats per minute (depth), and beats (area) between computer and observers using Bland-Altman analysis. Interobserver reliability was determined by calculating intraclass correlation and Spearman rank analysis. ResultsThe analysis (312 cases) showed excellent intraclass correlation (0.89-0.95) and very strong Spearman correlation (0.82-0.91). The detailed analysis of >100 decelerations in four cases revealed low bias between the computer and the two observers; width 1.4 and 1.4 seconds, depth 5.1 and 0.7 beats per minute, and area 0.1 and -1.7 beats. This was comparable to the bias between the two observers: 0.3 seconds (width), 4.4 beats per minute (depth) and 1.7 beats (area). The intraclass correlation was excellent (0.90-.98). ConclusionA novel computerized algorithm for intrapartum cardiotocography analysis is as accurate as gold standard visual assessment, with high correlation and low bias.

  • 21.
    Hafid, Abdelakram
    et al.
    Univ Sci & Technol Houari Boumediene, Lab Instrumentat, Algiers 16111, Algeria.;Univ Boras, Dept Text Technol, S-50332 Boras, Sweden..
    Benouar, Sara
    Univ Sci & Technol Houari Boumediene, Lab Instrumentat, Algiers 16111, Algeria.;Univ Boras, Dept Text Technol, S-50332 Boras, Sweden..
    Kedir-talha, Malika
    Univ Sci & Technol Houari Boumediene, Lab Instrumentat, Algiers 16111, Algeria..
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH). Karolinska Inst, Inst Environm Med, SE-17177 Stockholm, Sweden.;Karolinska Univ Hosp, Dept Clin Physiol, S-14186 Huddinge, Sweden..
    Attari, Mokhtar
    Univ Sci & Technol Houari Boumediene, Lab Instrumentat, Algiers 16111, Algeria..
    Seoane, Fernando
    Univ Boras, Swedish Sch Text, S-50190 Boras, Sweden.;Karolinska Inst, Dept Clin Sci Intervent & Technol, S-14186 Stockholm, Sweden.;Karolinska Univ Hosp, Dept Biomed Engn, S-14186 Stockholm, Sweden..
    Full Impedance Cardiography Measurement Device Using Raspberry PI3 and System-on-Chip Biomedical Instrumentation Solutions2018Ingår i: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 22, nr 6, s. 1883-1894Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Impedance cardiography (ICG) is a noninvasive method for monitoring cardiac dynamics using electrical bioimpedance (EBI) measurements. Since its appearance more than 40 years ago, ICG has been used for assessing hemodynamic parameters. This paper presents a measurement system based on two System on Chip (SoC) solutions and Raspberry PI, implementing both a full three-lead ECG recorder and an impedance cardiographer, for educational and research development purposes. Raspberry PI is a platform supporting Do-I t-Yourself project and education applications across the world. The development is part of Biosignal PI, an open hardware platform focusing in quick prototyping of physiological measurement instrumentation. The SoC used for sensing cardiac biopotential is the ADAS1000, and for the EBI measurement is the AD5933. The recordings were wirelessly transmitted through Bluetooth to a PC, where the waveforms were displayed, and hemodynamic parameters such as heart rate, stroke volume, ejection time and cardiac output were extracted from the ICG and ECG recordings. These results show how Raspberry PI can be used for quick prototyping using relatively widely available and affordable components, for supporting developers in research and engineering education. The design and development documents will be available on www.BiosignalPl.com, for open access under a Non Commercial-Share A like 4.0 International License.

  • 22. Hilderman, Marie
    et al.
    Qureshi, Abdul R
    Al-Abed, Yousef
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    Anderstam, Björn
    Bruchfeld, Annette
    Cholinergic anti-inflammatory pathway activity in dialysis patients: a role for neuroimmunomodulation?2015Ingår i: Clinical Kidney Journal, ISSN 2048-8505, E-ISSN 2048-8513, Vol. 8, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: The cholinergic anti-inflammatory pathway (CAP) modulates inflammatory responses through the vagus nerve and the α-7-nicotinic acetylcholine receptor (α7nAChR) on macrophages and immune cells. Sympathetic/parasympathetic imbalance and chronic inflammation are both linked to poor outcome in dialysis patients. The aim of this study was to investigate CAP activity in these patients.

    METHODS: Twenty dialysis patients, 12 hemodialysis (HD) and 8 peritoneal dialysis (PD) patients (12 male, 8 female; age range 47-83 years) and 8 controls (5 male, 3 female; age range 31-52 years) were analyzed for C-reactive protein (CRP), tumor necrosis factor (TNF), interleukin-1b (IL-1b), IL-6 and IL-10 at baseline. The cytokines were then assessed after whole blood stimulation ex vivo with lipopolysaccharide (LPS) (10 and 100 ng/mL) and again in the presence of 45 and 90 μmol/L GTS-21, a cholinergic α7nAChR agonist.

    RESULTS: CRP, TNF, IL-1 and IL-6 were significantly higher, whereas IL-10 was significantly lower at baseline in patients compared with controls. After LPS stimulation, TNF increased significantly more in patients than in controls but decreased to similar levels in both groups after addition of GTS-21. IL-6 attenuation was comparable with TNF and the IL-1b pattern was similar but remained significantly higher in patients. Interestingly, IL-10 increased after GTS-21 in a dose-dependent manner, but only in patients. Results in HD and PD patients did not differ.

    CONCLUSIONS: The response of immune cells after LPS exposure and cholinergic stimulation suggests a functional CAP in dialysis patients. It may thus be possible to target the α7nAChR control of cytokine release as an anti-inflammatory strategy and thereby improve outcome in these patients.

  • 23. Hilderman, Marie
    et al.
    Qureshi, Abdul Rashid
    Abtahi, Farhad
    Witt, Nils
    Jägren, Christina
    Olbers, Joakim
    Delle, Martin
    Lindecrantz, Kaj
    Bruchfeld, Annette
    The cholinergic anti-inflammatory pathway in resistant hypertension treated with renal denervation2019Ingår i: Molecular medicine (Cambridge, Mass. Print), ISSN 1076-1551, E-ISSN 1528-3658, Vol. 25, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Renal denervation (RDN) reduces sympathetic tone and may alter the sympathetic-parasympathetic balance. The autonomic nervous system is partly a regulator of innate immunity via the cholinergic anti-inflammatory pathway (CAP) which inhibits inflammation via the vagus nerve. Placental Growth Factor (PlGF) influences a neuro-immunological pathway in the spleen which may contribute to hypertension. The aim of this study was to investigate if modulation of renal sympathetic nerve activity affects CAP in terms of cytokine release as well as levels of PlGF.

  • 24.
    Karbalaie, Abdolamir
    et al.
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap.
    Abtahi, Farhad
    Fatemi, A.
    Etehadtavakol, M.
    Emrani, Z.
    Erlandsson, Björn-Erik
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap.
    Elliptical broken line method for calculating capillary density in nailfold capillaroscopy: Proposal and evaluation2017Ingår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 113, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nailfold capillaroscopy is a practical method for identifying and obtaining morphological changes in capillaries which might reveal relevant information about diseases and health. Capillaroscopy is harmless, and seems simple and repeatable. However, there is lack of established guidelines and instructions for acquisition as well as the interpretation of the obtained images; which might lead to various ambiguities. In addition, assessment and interpretation of the acquired images are very subjective. In an attempt to overcome some of these problems, in this study a new modified technique for assessment of nailfold capillary density is introduced. The new method is named elliptic broken line (EBL) which is an extension of the two previously known methods by defining clear criteria for finding the apex of capillaries in different scenarios by using a fitted elliptic. A graphical user interface (GUI) is developed for pre-processing, manual assessment of capillary apexes and automatic correction of selected apexes based on 90° rule. Intra- and inter-observer reliability of EBL and corrected EBL is evaluated in this study. Four independent observers familiar with capillaroscopy performed the assessment for 200 nailfold videocapillaroscopy images, form healthy subject and systemic lupus erythematosus patients, in two different sessions. The results show elevation from moderate (ICC = 0.691) and good (ICC = 0.753) agreements to good (ICC = 0.750) and good (ICC = 0.801) for intra- and inter-observer reliability after automatic correction of EBL. This clearly shows the potential of this method to improve the reliability and repeatability of assessment which motivates us for further development of automatic tool for EBL method.

  • 25.
    Karbalaie, Abdolamir
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    Etehadtavakol, Mahnaz
    Isfahan University of Medical Sciences, Isfahan, Iran.
    Abtahi, Farhad
    Fatemi, Alimohammad
    Rheumatology Section, Department of Internal Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
    Emrani, Zahra
    Medical Image and Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
    Erlandsson, Björn-Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Image Enhancement Effect on Inter and Intra-observer Reliability of Nailfold Capillary Assessment2018Ingår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Nailfold capillaroscopy (NC) is a diagnostic imaging technique that is used to assess the blood capillary network in the nailfold area. NC is routinely used for patients with microcirculation problems, such as systemic sclerosis and other connective tissue diseases.  Experts commonly use subjective evaluation as a reference point in images of nailfold video capillaroscopy, so it is important to reduce the inherent ambiguities in human judgment and diagnosis. Image quality is an important factor that affects measurement error and assessment time of NC images.

    Objective: In this study, a new image enhancement technique was introduced and evaluated subjectively.

    Methods: In total, 475 nailfold video capillaroscopy images from 18 healthy subjects and 41 systemic lupus erythematosus patients were used. The images were randomly divided into two sets, one each with 275 and 200. Eight independent observers who were familiar with the capillaroscopy technique participated in this study. The set of 275 images was evaluated by three observers with the forced–choice pairwise comparison method. Elliptic broken line (EBL) was used to count the number of capillaries. The intra- and inter-observer reliability of the original and enhanced images was evaluated on 200 images by five observers.

    Result: Except for eight images, all observers preferred the enhanced images in the visual quality comparison method. The intra-class correlation coefficient (ICC) of intra- and inter-observer reliability increased from 0.76-0.84 to 0.82-0.89, respectively, when using the enhancement method.

    Conclusion: By improving the image quality, more capillary details will be visible, and an observer can document more details that may not be visible in the original image and can do so more efficiently.

  • 26.
    Karbalaie, Abdolamir
    et al.
    KTH, Skolan för teknik och hälsa (STH).
    Fatemi, Alimohammad
    Department of Rheumatology, Alzahra Hospital, Isfahan University of Medical Sciences.
    Etehadtavakol, Mahnaz
    Medical Image and Signal Processing Research Center, Isfahan University of Medical Sciences.
    Abtahi, Farhad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik. Department of Clinical Science, Intervention and Technology, Karolinska Institute (KI).
    Emrani, Zahra
    Medical Image and Signal Processing Research Center, Isfahan University of Medical Sciences.
    Erlandsson, Björn-Erik
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    Counting Capillaries in Nailfold Capillaroscopy:State of the Art and a Proposed Method2016Ingår i: 2016 IEEE EMBS CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES (IECBES), IEEE, 2016, , s. 5s. 170-174Konferensbidrag (Refereegranskat)
    Abstract [en]

    Capillaries play a crucial role in the microcirculatory system by exchanging metabolic substrates and waste products between blood and various tissues. The behavior of capillaries is affiliated with the number of capillaries per unit volume of tissue. Among the various noninvasive techniques available for analyzing skin microcirculation, nailfold capillaroscopyis considered to be a simple and easy-to-perform technique that allows a direct in-vivo visualization of the capillary network.Capillary density is one of the most important parameters in the studies involving capillaroscopy images. Capillary density in most of studies is defined as the number of capillaries in a one-millimeter span of the distal row in each finger or toe. This definition is silent about counting or excluding the number of the capillary with different shapes. However, there is no single standard for counting the number of capillaries in a span of one millimeter. In this paper, a novel method is proposed for determining the nailfold capillary density. This method is a modified combination of two existing techniques: the direct observation and the 90◦ method.Compared to the two existing approaches, the proposed method is more straightforward and easy to use for cases in which the capillaries have different shapes and sizes. Through different examples, we have shown how this method can be used to select the apex point of the capillary and subsequently count the number of capillaries with several papillae.

  • 27.
    Lind, Carl Mikael
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet.
    Yang, Liyun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet.
    Abtahi, Farhad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet.
    Hanson, Lars
    School of Engineering Science, University of Skövde; Global Industrial Development, Scania CV, Södertälje.
    Lindecrantz, Kaj
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet; Faculty of Textiles, University of Borås, Borås, Sweden.
    Lu, Ke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH). Unit of Occupational medicine, Karolinska Institutet.
    Forsman, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet.
    Eklund, Jörgen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Unit of Occupational medicine, Karolinska Institutet.
    Reducing postural load in order picking through a smart workwear system using real-time vibrotactile feedbackManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Vibrotactile feedback training may be one possible method for interventions that target at learning better work technique and improving postures in manual handling. The aim of this study was to evaluate the effect of real-time vibrotactile feedback using a smart workwear system for work postures intervention in industrial order picking. Fifteen workers at an industrial manufacturing plant performed order-picking tasks, in which the vibrotactile feedback was used for postural training at work. The trunk and upper arm postures were recorded by the system. Questionnaires and semi-structured interviews were conducted about the users’ experience of the system. The results showed reduced time in adverse postures for the trunk and upper arms when the workers received feedback, and for trunk postures also after feedback withdrawal. The workers perceived the system as usable, comfortable and supportive for learning.

  • 28.
    Lu, Ke
    et al.
    KTH, Skolan för teknik och hälsa (STH).
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH).
    Nordström, Lennart
    Lindqvist, Pelle
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH).
    Software tool for fetal heart rate signal analysis2015Konferensbidrag (Refereegranskat)
  • 29.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Boras, Sweden.
    Abtahi, Shirin
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institute, Sweden.
    Ellegard, L.
    Johannsson, G.
    Bosaeus, I.
    Ward, L C
    Slightly superior performance of bioimpedance spectroscopy over single frequency regression equations for assessment of total body water2015Ingår i: Engineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE, IEEE conference proceedings, 2015, s. 3707-3710Konferensbidrag (Refereegranskat)
    Abstract [en]

    Electrical bioimpedance has been used for several decades to assess body fluid distribution and body composition by using single frequency and bioimpedance spectroscopic (BIS) techniques. It remains uncertain whether BIS methods have better performance compare to single frequency regression equations. In this work the performance of two BIS methods and four different 50 kHz single frequency prediction equations was studied in a data set of wrist-to-ankle tetrapolar BIS measurements (5-1000 kHz) together with reference values of total body water obtained by tritium dilution in 92 patients. Data were compared using regression techniques and BlandAltman plots. The results of this study showed that all methods produced similarly high correlation and concordance coefficients, indicating good accuracy as a method. Limits of agreement analysis indicated that the population level performance of Sun’s prediction equations was very similar to the performance of both BIS methods. However, BIS methods in practice have slightly better predictive performance than the single-frequency equations as judged by higher correlation and the limits of agreement from the Bland-Altman analysis. In any case, the authors believe that an accurate evaluation of performance of the methods cannot be done as long as the evaluation is done using Bland-Altman analysis, the commonly accepted technique for this kind of performance comparisons.

  • 30.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Univ Boras, Fac Care Sci Work Life & Social Welfare, Sweden.
    Abtahi, Shirin
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Inst, Dept Clin Sci Intervent & Technol, Sweden.
    Ellegård, Lars
    Johannsson, Gudmundur
    Bosaeus, Ingvar
    Ward, Leigh C
    Mean Expected Error in Prediction of Total Body Water: A True Accuracy Comparison between Bioimpedance Spectroscopy and Single Frequency Regression Equations2015Ingår i: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, artikel-id 656323Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For several decades electrical bioimpedance (EBI) has been used to assess body fluid distribution and body composition. Despite the development of several different approaches for assessing total body water (TBW), it remains uncertain whether bioimpedance spectroscopic (BIS) approaches are more accurate than single frequency regression equations. The main objective of this study was to answer this question by calculating the expected accuracy of a single measurement for different EBI methods. The results of this study showed that all methods produced similarly high correlation and concordance coefficients, indicating good accuracy as a method. Even the limits of agreement produced from the Bland-Altman analysis indicated that the performance of single frequency, Sun’s prediction equations, at population level was close to the performance of both BIS methods; however, when comparing the Mean Absolute Percentage Error value between the single frequency prediction equations and the BIS methods, a significant difference was obtained, indicating slightly better accuracy for the BIS methods. Despite the higher accuracy of BIS methods over 50 kHz prediction equations at both population and individual level, the magnitude of the improvement was small. Such slight improvement in accuracy of BIS methods is suggested insufficient to warrant their clinical use where the most accurate predictions of TBW are required, for example, when assessing over-fluidic status on dialysis. To reach expected errors below 4-5%, novel and individualized approaches must be developed to improve the accuracy of bioimpedance-based methods for the advent of innovative personalized health monitoring applications.

  • 31.
    Seoane, Fernando
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Soroudi, Azadeh
    Högskolan i Borås, Sverige.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Lu, Ke
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Skrifvars, Mikael
    Högskolan i Borås, Sverige.
    Printed Electronics Enabling a Textile-friendly Interconnection between Wearable Measurement Instrumentation & Sensorized Garments2016Konferensbidrag (Refereegranskat)
  • 32. Seoane, Fernando
    et al.
    Soroudi, Azadeh
    Lu, Ke
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Abtahi, Farhad
    Nilsson, David
    Nilsson, Marie
    Skrifvars, Mikael
    Textile-Friendly Interconnection between WearableMeasurement Instrumentation and SensorizedGarments – Initial Performance Evaluation forElectrocardiogram RecordingsManuskript (preprint) (Övrigt vetenskapligt)
  • 33.
    Vega-Barbas, Mario
    et al.
    Karolinska Inst, Inst Environm Med, Solnavagen 1, S-17177 Solna, Sweden.
    Diaz-Olivares, Jose A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Lu, Ke
    Karolinska Inst, Inst Environm Med, Solnavagen 1, S-17177 Solna, Sweden..
    Forsman, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Karolinska Inst, Inst Environm Med, Solnavagen 1, S-17177 Solna, Sweden.
    Seoane, Fernando
    Karolinska Inst, Dept Clin Sci Intervent & Technol, Halsovagen 7, S-14157 Huddinge, Sweden.;Univ Boras, Swedish Sch Text, Allegatan 1, S-50190 Boras, Sweden.;Karolinska Univ Hosp, Dept & T Biomed Engn, S-17176 Solna, Sweden..
    Abtahi, Farhad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi. Karolinska Inst, Inst Environm Med, Solnavagen 1, S-17177 Solna, Sweden.
    P-Ergonomics Platform: Toward Precise, Pervasive, and Personalized Ergonomics using Wearable Sensors and Edge Computing2019Ingår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 19, nr 5, artikel-id 1225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Preventive healthcare has attracted much attention recently. Improving people's lifestyles and promoting a healthy diet and wellbeing are important, but the importance of work-related diseases should not be undermined. Musculoskeletal disorders (MSDs) are among the most common work-related health problems. Ergonomists already assess MSD risk factors and suggest changes in workplaces. However, existing methods are mainly based on visual observations, which have a relatively low reliability and cover only part of the workday. These suggestions concern the overall workplace and the organization of work, but rarely includes individuals' work techniques. In this work, we propose a precise and pervasive ergonomic platform for continuous risk assessment. The system collects data from wearable sensors, which are synchronized and processed by a mobile computing layer, from which exposure statistics and risk assessments may be drawn, and finally, are stored at the server layer for further analyses at both individual and group levels. The platform also enables continuous feedback to the worker to support behavioral changes. The deployed cloud platform in Amazon Web Services instances showed sufficient system flexibility to affordably fulfill requirements of small to medium enterprises, while it is expandable for larger corporations. The system usability scale of 76.6 indicates an acceptable grade of usability.

  • 34. Wollmann, Thomas
    et al.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Eghdam, Abouzar
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Haag, Martin
    Koch, Sabine
    User-Centred Design and Usability Evaluation of a Heart Rate Variability Biofeedback Game2016Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 4, s. 5531-5539Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background and objective: Reduced heart rate variability (HRV) is an indicatorof a malfunctioning autonomic nervous system. Resonant frequencybreathing is a potential non-invasive means of intervention for improvingthe balance of the autonomic nervous system and increasing HRV. However,such breathing exercises are regarded as boring and monotonous tasks.The use of gaming elements (gamification) or a full gaming experience is awell-recognised method for achieving higher motivation and engagement invarious tasks. However, there is limited documented knowledge on how todesign a game for breathing exercises. In particular, the influence of additionalinteractive elements on the main course of training has not yet beenexplored. In this study, we evaluated the satisfaction levels achieved usingdifferent game elements and how disruptive they were to the main task, i.e.,paced breathing training.

    Methods: An Android flight game was developed with three game modes thatdiffer in the degrees of multitasking they require. Design, development and evaluation were conducted using a user-centred approach, including contextanalysis, the design of game principle mock-ups, the selection of game principlesthrough a survey, the design of the game mechanics and GUI mock-up,icon testing and the performance of a summative study through user questionnairesand interviews. A summative evaluation of the developed gamewas performed with 11 healthy participants (ages 40-67) in a controlled setting.Results: The results confirm the potential of video games for motivatingplayers to engage in HRV biofeedback training. The highest training performanceon the first try was achieved through pure visualisation rather thanin a multitasking mode. Players had higher motivation to play the morechallenging game and were more interested in long-term engagement.Conclusion: A framework for gamified HRV biofeedback research is presented.It has been shown that multitasking has considerable influence onHRV biofeedback and should be used with an adaptive challenge level.

  • 35.
    Yang, Liyun
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Abtahi, Farhad
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Eklund, Jörgen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Hanson, Lars
    School of Engineering Science, University of Skövde.
    Lindecrantz, Kaj
    KTH.
    Forsman, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Carl, Lind
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Smart workwear system with real-time vibrotactile feedback for improving postural behaviour in industry2019Ingår i: From research to evidence based sustainable interventions and practices: Book of Abstracts, Bologna, Italy, 2019, s. 160-Konferensbidrag (Refereegranskat)
  • 36.
    Yang, Liyun
    et al.
    KTH, Skolan för teknik och hälsa (STH).
    Lu, Ke
    Abtahi, Farhad
    Lindecrantz, Kaj
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Seoane, Fernando
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Forsman, Mikael
    Institute of Environmental Medicine, Karolinska Institutet.
    Eklund, Jörgen
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    A pilot study of using smart clothes for physicalworkload assessment2017Ingår i: JOY AT WORK, Lund, Sweden, 2017, s. 169-170Konferensbidrag (Refereegranskat)
1 - 36 av 36
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