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Publications (10 of 17) Show all publications
Yang, L., Lu, K., Forsman, M., Lindecrantz, K., Seoane, F., Ekblom, Ö. & Eklund, J. (2019). Evaluation of physiological workload assessment methods using heart rate and accelerometry for a smart wearable system. Ergonomics
Open this publication in new window or tab >>Evaluation of physiological workload assessment methods using heart rate and accelerometry for a smart wearable system
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2019 (English)In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847Article in journal (Other academic) Accepted
Abstract [en]

Work metabolism (WM) can be accurately estimated by oxygen consumption (VO2), which is commonly assessed by heart rate (HR) in field studies. However, the VO2–HR relationship is influenced by individual capacity and activity characteristics. The purpose of this study was to evaluate three models for estimating WM compared with indirect calorimetry, during simulated work activities. The techniques were: the HR-Flex model; HR branched model, combining HR with hip-worn accelerometers (ACC); and HR + arm-leg ACC model, combining HR with wrist- and thigh-worn ACC. Twelve participants performed five simulated work activities and three submaximal tests. The HR + arm-leg ACC model had the overall best performance with limits of agreement (LoA) of −3.94 and 2.00 mL/min/kg, while the HR-Flex model had −5.01 and 5.36 mL/min/kg and the branched model, −6.71 and 1.52 mL/min/kg. In conclusion, the HR + arm-leg ACC model should, when feasible, be preferred in wearable systems for WM estimation.

Keywords
Heart rate; work metabolism; motion sensing; wearable sensors; risk assessment; estimation models
National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-239148 (URN)10.1080/00140139.2019.1566579 (DOI)000468779800007 ()2-s2.0-85062366366 (Scopus ID)
Funder
AFA Insurance, 150039
Note

QC 20190218

Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2019-06-11Bibliographically approved
Lu, K., Yang, L., Abtahi, F., Lindecrantz, K., Rödby, K. & Seoane, F. (2019). Wearable cardiorespiratory monitoring system for unobtrusive free-living energy expenditure tracking. In: IFMBE Proceedings: . Paper presented at World Congress on Medical Physics and Biomedical Engineering, WC 2018, 3 June 2018 through 8 June 2018 (pp. 433-437). Springer (1)
Open this publication in new window or tab >>Wearable cardiorespiratory monitoring system for unobtrusive free-living energy expenditure tracking
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2019 (English)In: IFMBE Proceedings, Springer, 2019, no 1, p. 433-437Conference paper, Published paper (Refereed)
Abstract [en]

In this work, we want to introduce combined heart rate and respiration monitoring for more accurate energy expenditure tracking on free-living subjects. We have developed a wearable cardiorespiratory monitoring system with unobtrusive heart rate measurement and ventilation estimation function for this purpose. The system is based on a garment with integrated textile electrodes for one-lead electrocardiogram and impedance pneumography measurements. A pilot experiment has been performed to prove the concept and to evaluate the characteristics of heart rate and ventilation estimated by our system in relation to energy expenditure. In the experiment, ventilation shows a better linearity in relation to the energy expenditure at the low intensity region than heart rate. Based on these characteristics, a model combining heart rate and ventilation for energy expenditure estimation is proposed which shows a significantly lower estimation error than the heart rate only model.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Energy expenditure, Impedance pneumography, Wearable devices, Biomedical engineering, Patient monitoring, Wearable technology, Energy expenditure estimation, Estimation function, Heart rate measurements, Respiration monitoring, Textile electrodes, Heart
National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-236338 (URN)10.1007/978-981-10-9035-6_80 (DOI)000450908300080 ()2-s2.0-85048260818 (Scopus ID)
Conference
World Congress on Medical Physics and Biomedical Engineering, WC 2018, 3 June 2018 through 8 June 2018
Funder
VINNOVA
Note

QC 20181109

Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2018-12-11Bibliographically approved
Lu, K., Holzmann, M., Abtahi, F., Lindecrantz, K., Lindqvist, P. G. & Nordström, L. (2018). Fetal heart rate short term variation during labor in relation to scalp blood lactate concentration. Acta Obstetricia et Gynecologica Scandinavica, 97(10), 1274-1280
Open this publication in new window or tab >>Fetal heart rate short term variation during labor in relation to scalp blood lactate concentration
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2018 (English)In: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, Vol. 97, no 10, p. 1274-1280Article in journal (Refereed) Published
Abstract [en]

IntroductionFetal heart rate short term variation (STV) decreases with severe chronic hypoxia in the antenatal period. However, only limited research has been done on STV during labor. We have tested a novel algorithm for a valid baseline estimation and calculated STV. To explore the value of STV during labor, we compared STV with fetal scalp blood (FBS) lactate concentration, an early marker in the hypoxic process. Material and methodsSoftware was developed which estimates baseline frequency using a novel algorithm and thereby calculates STV according to Dawes and Redman in up to four 30-minute blocks prior to each FBS. Cardiotocography traces from 1070 women in labor who had had FBS performed on 2134 occasions were analyzed. ResultsIn acidemic cases (lactate >4.8mmol/L; Lactate Pro), median STV 30minutes prior to FBS was 7.10milliseconds compared with 6.09milliseconds in the preacidemic (4.2-4.8mmol/L) and 5.23milliseconds in the normal (<4.2mmol/L) groups (P<.05). There was a positive correlation between lactate and STV (rho=0.16-0.24; P<.05). Median lactate concentration in cases with STV <3.0milliseconds (n=160) was 2.3mmol/L. When 2 FBS were performed within 60minutes the change rate of lactate correlated to STV (rho=0.33; P<.001). Cases with increasing lactate concentration had a median STV of 5.29milliseconds vs 4.41milliseconds in those with decreasing lactate (P<.001). ConclusionsIn the early stages of intrapartum hypoxia, STV increases, contrary to findings regarding chronic hypoxia in the antenatal period. The increase in the adrenergic surge is a likely explanation.

Place, publisher, year, edition, pages
Wiley, 2018
Keywords
computer analysis, fetal heart rate monitoring, fetal scalp blood sampling, hypoxia, intrapartum, lactate, short-term variation
National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:kth:diva-235432 (URN)10.1111/aogs.13390 (DOI)000444070900017 ()29799630 (PubMedID)2-s2.0-85052990496 (Scopus ID)
Note

QC 20180927

Available from: 2018-09-27 Created: 2018-09-27 Last updated: 2018-10-22Bibliographically approved
Lu, K., Holzmann, M., Abtahi, F., Lindecrantz, K., Lindqvist, P. & Nordström, L. (2018). Fetal heart rate short term variation (STV) during labour in relation to early stages of hypoxia: An observational study. British Journal of Obstetrics and Gynecology, 125, 55-55
Open this publication in new window or tab >>Fetal heart rate short term variation (STV) during labour in relation to early stages of hypoxia: An observational study
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2018 (English)In: British Journal of Obstetrics and Gynecology, ISSN 1470-0328, E-ISSN 1471-0528, Vol. 125, p. 55-55Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:kth:diva-227233 (URN)000430280500136 ()
Note

QC 20180514

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Lu, K., Yang, L., Seoane, F., Abtahi, F., Forsman, M. & Lindecrantz, K. (2018). Fusion of heart rate, respiration and motion measurements from a wearable sensor system to enhance energy expenditure estimation. Sensors, 18(9), Article ID 3092.
Open this publication in new window or tab >>Fusion of heart rate, respiration and motion measurements from a wearable sensor system to enhance energy expenditure estimation
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 9, article id 3092Article in journal (Refereed) Published
Abstract [en]

This paper presents a new method that integrates heart rate, respiration, and motion information obtained from a wearable sensor system to estimate energy expenditure. The system measures electrocardiography, impedance pneumography, and acceleration from upper and lower limbs. A multilayer perceptron neural network model was developed, evaluated, and compared to two existing methods, with data from 11 subjects (mean age, 27 years, range, 21–65 years) who performed a 3-h protocol including submaximal tests, simulated work tasks, and periods of rest. Oxygen uptake was measured with an indirect calorimeter as a reference, with a time resolution of 15 s. When compared to the reference, the new model showed a lower mean absolute error (MAE = 1.65 mL/kg/min, R2 = 0.92) than the two existing methods, i.e., the flex-HR method (MAE = 2.83 mL/kg/min, R2 = 0.75), which uses only heart rate, and arm-leg HR+M method (MAE = 2.12 mL/kg/min, R2 = 0.86), which uses heart rate and motion information. As indicated, this new model may, in combination with a wearable system, be useful in occupational and general health applications. 

Place, publisher, year, edition, pages
MDPI AG, 2018
Keywords
Accelerometer, Energy expenditure, Impedance pneumography, Neural network, Wearable device, Accelerometers, Heart, Neural networks, Energy expenditure estimation, Mean absolute error, Motion measurements, Multi-layer perceptron neural networks, Wearable devices, Wearable sensor systems, Wearable sensors
National Category
Health Sciences
Identifiers
urn:nbn:se:kth:diva-236691 (URN)10.3390/s18093092 (DOI)000446940600351 ()30223429 (PubMedID)2-s2.0-85053711948 (Scopus ID)
Note

Export Date: 22 October 2018; Article; Correspondence Address: Ke, L.; School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Hälsovägen 11C, Sweden; email: kelu@kth.se; Funding details: 18454; Funding details: Dnr 150039; Funding text: Funding: This work was supported by AFA Insurance under Grant Dnr 150039, EIT Health under project no. 18454 “Wellbeing, Health and Safety @ Work”, and CSC Scholarship Council. QC 20181112

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-20Bibliographically approved
Yang, L., Lu, K., Diaz-Olivares, J. A., Seoane, F., Lindecrantz, K., Forsman, M., . . . Eklund, J. A. E. (2018). Towards Smart Work Clothing for Automatic Risk Assessment of Physical Workload. IEEE Access, 6, 40059-40072
Open this publication in new window or tab >>Towards Smart Work Clothing for Automatic Risk Assessment of Physical Workload
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2018 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 40059-40072Article in journal (Refereed) Published
Abstract [en]

Work-related musculoskeletal and cardiovascular disorders are still prevalent in today's working population. Nowadays, risk assessments are usually performed via self-reports or observations, which have relatively low reliability. Technology developments in textile electrodes (textrodes), inertial measurement units, and the communication and processing capabilities of smart phones/tablets provide wearable solutions that enable continuous measurements of physiological and musculoskeletal loads at work with sufficient reliability and resource efficiency. In this paper, a wearable system integrating textrodes, motion sensors, and real-time data processing through a mobile application was developed as a demonstrator of risk assessment related to different types and levels of workload and activities. The system was demonstrated in eight subjects from four occupations with various workload intensities, during which the heart rate and leg motion data were collected and analyzed with real-time risk assessment and feedback. The system showed good functionality and usability as a risk assessment tool. The results contribute to designing and developing future wearable systems and bring new solutions for the prevention of work-related disorders.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Energy expenditure, sitting, standing, occupational health, preventive healthcare, wearable sensors, sensorized garments
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:kth:diva-233434 (URN)10.1109/ACCESS.2018.2855719 (DOI)000441214800001 ()2-s2.0-85050003765 (Scopus ID)
Note

QC 20180821

Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-11-20Bibliographically approved
Gyllencreutz, E., Lu, K., Lindecrantz, K., Lindqvist, P., Nordström, L., Holzmann, M. & Abtahi, F. (2018). Validation of a computerised algorithm to quantify fetal heart rate deceleration area: An observational study. British Journal of Obstetrics and Gynecology, 125, 54-54
Open this publication in new window or tab >>Validation of a computerised algorithm to quantify fetal heart rate deceleration area: An observational study
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2018 (English)In: British Journal of Obstetrics and Gynecology, ISSN 1470-0328, E-ISSN 1471-0528, Vol. 125, p. 54-54Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-227232 (URN)000430280500135 ()
Note

QC 20180514

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Gyllencreutz, E., Lu, K., Lindecrantz, K., Lindqvist, P. G., Nordström, L., Holzmann, M. & Abtahi, F. (2018). Validation of a computerized algorithm to quantify fetal heart rate deceleration area. Acta Obstetricia et Gynecologica Scandinavica, 97(9), 1137-1147
Open this publication in new window or tab >>Validation of a computerized algorithm to quantify fetal heart rate deceleration area
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2018 (English)In: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, Vol. 97, no 9, p. 1137-1147Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
Cardiotocography, computer-assisted signal processing, deceleration, fetal monitoring, interobserver variation
National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:kth:diva-233267 (URN)10.1111/aogs.13370 (DOI)000440679900010 ()29768660 (PubMedID)2-s2.0-85051058017 (Scopus ID)
Note

QC 20180816

Available from: 2018-08-16 Created: 2018-08-16 Last updated: 2018-08-16Bibliographically approved
Lu, K. (2018). Wearable Solutions for P-Health at Work: Precise, Pervasive and Preventive. (Doctoral dissertation). KTH Royal Institute of Technology
Open this publication in new window or tab >>Wearable Solutions for P-Health at Work: Precise, Pervasive and Preventive
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With a demographic change towards an older population, the structure of the labor force is shifting, and people are expected to work longer within their extended life span. However, for many people, wellbeing has been compromised by work-related problems before they reach the retirement age. Prevention of chronic diseases such as cardiovascular diseases and musculoskeletal disorders is needed to provide a sustainable working life. Therefore, pervasive tools for risk assessment and intervention are needed. The vision is to use wearable technologies to promote a sustainable work life, to be more detailed, to develop a system that integrates wearable technologies into workwear to provide pervasive and precise occupational disease prevention. This thesis presents some efforts towards this vision, including system-level design for a wearable risk assessment and intervention system, as well as specific insight into solutions for in-field assessment of physical workload and technologies to make smart sensing garments. The overall system is capable of providing unobtrusive monitoring of several signs, automatically estimating risk levels and giving feedback and reports to different stakeholders. The performance and usability of current energy expenditure estimation methods based on heart rate monitors and accelerometers were examined in occupational scenarios. The usefulness of impedance pneumography-based respiration monitoring for energy expenditure estimation was explored. A method that integrates heart rate, respiration and motion information using a neuronal network for enhancing the estimation is shown. The sensing garment is an essential component of the wearable system. Smart textile solutions that improve the performance, usability and manufacturability of sensing garments, including solutions for wiring and textile-electronics interconnection as well as an overall garment design that utilizes different technologies, are demonstrated.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. p. 42
Series
TRITA-CBH-FOU ; 2018-59
Keywords
wearable technology, occupational health, energy expenditure, smart textile
National Category
Medical Engineering
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-239156 (URN)978-91-7873-042-1 (ISBN)
Public defence
2018-12-10, Sal T2, Hälsovägen 11, Flemingsberg, 10:00 (English)
Opponent
Supervisors
Note

QC 20181119

Available from: 2018-11-19 Created: 2018-11-16 Last updated: 2018-11-19Bibliographically approved
Yang, L., Lu, K., Abtahi, F., Lindecrantz, K., Seoane, F., Forsman, M. & Eklund, J. (2017). A pilot study of using smart clothes for physicalworkload assessment. In: JOY AT WORK: . Paper presented at Conference Proceedings of Nordic Ergonomics Society 49th Annual Conference (pp. 169-170). Lund, Sweden
Open this publication in new window or tab >>A pilot study of using smart clothes for physicalworkload assessment
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2017 (English)In: JOY AT WORK, Lund, Sweden, 2017, p. 169-170Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Lund, Sweden: , 2017
Keywords
Energy expenditure estimation, pulmonary ventilation, heart rate.
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-227864 (URN)978-91-7753-152-4 (ISBN)
Conference
Conference Proceedings of Nordic Ergonomics Society 49th Annual Conference
Note

QC 20180614

Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-06-14Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3256-9029

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