| 1. |
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| 2. |
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| 3. |
- Beyer, J., et al.
(författare)
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Maintaining success, reducing treatment burden, focusing on survivorship: highlights from the third European consensus conference on diagnosis and treatment of germ-cell cancer
- 2013
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Ingår i: Annals of Oncology. - : Elsevier BV. - 1569-8041 .- 0923-7534. ; 24:4, s. 878-888
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Forskningsöversikt (refereegranskat)abstract
- In November 2011, the Third European Consensus Conference on Diagnosis and Treatment of Germ-Cell Cancer (GCC) was held in Berlin, Germany. This third conference followed similar meetings in 2003 (Essen, Germany) and 2006 (Amsterdam, The Netherlands) [Schmoll H-J, Souchon R, Krege S et al. European consensus on diagnosis and treatment of germ-cell cancer: a report of the European Germ-Cell Cancer Consensus Group (EGCCCG). Ann Oncol 2004; 15: 1377-1399; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part I. Eur Urol 2008; 53: 478-496; Krege S, Beyer J, Souchon R et al. European consensus conference on diagnosis and treatment of germ-cell cancer: a report of the second meeting of the European Germ-Cell Cancer Consensus group (EGCCCG): part II. Eur Urol 2008; 53: 497-513]. A panel of 56 of 60 invited GCC experts from all across Europe discussed all aspects on diagnosis and treatment of GCC, with a particular focus on acute and late toxic effects as well as on survivorship issues. The panel consisted of oncologists, urologic surgeons, radiooncologists, pathologists and basic scientists, who are all actively involved in care of GCC patients. Panelists were chosen based on the publication activity in recent years. Before the meeting, panelists were asked to review the literature published since 2006 in 20 major areas concerning all aspects of diagnosis, treatment and follow-up of GCC patients, and to prepare an updated version of the previous recommendations to be discussed at the conference. In addition, similar to 50 E-vote questions were drafted and presented at the conference to address the most controversial areas for a poll of expert opinions. Here, we present the main recommendations and controversies of this meeting. The votes of the panelists are added as online supplements.
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| 4. |
- Azevedo, Flavio, et al.
(författare)
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Social and moral psychology of COVID-19 across 69 countries
- 2023
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Ingår i: Scientific Data. - : NATURE PORTFOLIO. - 2052-4463. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has affected all domains of human life, including the economic and social fabric of societies. One of the central strategies for managing public health throughout the pandemic has been through persuasive messaging and collective behaviour change. To help scholars better understand the social and moral psychology behind public health behaviour, we present a dataset comprising of 51,404 individuals from 69 countries. This dataset was collected for the International Collaboration on Social & Moral Psychology of COVID-19 project (ICSMP COVID-19). This social science survey invited participants around the world to complete a series of moral and psychological measures and public health attitudes about COVID-19 during an early phase of the COVID-19 pandemic (between April and June 2020). The survey included seven broad categories of questions: COVID-19 beliefs and compliance behaviours; identity and social attitudes; ideology; health and well-being; moral beliefs and motivation; personality traits; and demographic variables. We report both raw and cleaned data, along with all survey materials, data visualisations, and psychometric evaluations of key variables.
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| 5. |
- Van Bavel, Jay J., et al.
(författare)
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National identity predicts public health support during a global pandemic
- 2022
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Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Understanding collective behaviour is an important aspect of managing the pandemic response. Here the authors show in a large global study that participants that reported identifying more strongly with their nation reported greater engagement in public health behaviours and support for public health policies in the context of the pandemic. Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = -0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.
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| 6. |
- Bahi, R., et al.
(författare)
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Ischemia is not an independent predictive factor of chronic renal failure after partial nephrectomy in a solitary kidney in patients without pre-operative renal insufficiency
- 2015
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Ingår i: Progrès en urologie (Paris). - : Elsevier BV. - 1166-7087. ; 25:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the influence of vascular clamping and ischemia time on long-term post-operative renal function following partial nephrectomy (PN) for cancer in a solitary kidney.Patients and methods: This is a retrospective study including 259 patients managed by PN between 1979 and 2010 in 13 centers. Clamping use, technique choice (pedicular or parenchymal clamping), ischemia time, and peri-operative data were collected. Pre-operative and last follow-up glomerular filtration rates were compared. A multivariate analysis using a Cox model was performed to assess the impact of ischemia on post-operative chronic renal failure risk.Results: Mean tumor size was 4.0 ± 2.3 cm and mean pre-operative glomerular filtration rate was 60.8 ± 18.9 mL/min. One hundred and six patients were managed with warm ischemia (40.9%) and 53 patients with cold ischemia (20.5%). Thirty patients (11.6%) have had a chronic kidney disease. In multivariate analysis, neither vascular clamping (P = 0.44) nor warm ischemia time (P = 0.1) were associated with a pejorative evolution of renal function. Pre-operative glomerular filtration rate (P < 0.0001) and blood loss volume (P = 0.02) were significant independent predictive factors of long-term renal failure.Conclusion: Renal function following PN in a solitary kidney seems to depend on non-reversible factors such as pre-operative glomerular filtration rate. Our findings minimize the role of vascular clamping and ischemia time, which were not significantly associated with chronic renal failure risk in our study.
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| 7. |
- Garcia, J., et al.
(författare)
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Temporal evolution of traditional versus transformed ECG-based indexes in patients with induced myocardial ischemia
- 2000
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Ingår i: Journal of Electrocardiology. - 1532-8430. ; 33:1, s. 37-47
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Tidskriftsartikel (refereegranskat)abstract
- The time course of changes in the electrocardiogram as a result of myocardial ischemia induced during prolonged coronary angioplasty has been studied. We have analyzed the electrocardiogram evolution during the occlusion in terms of the Ischemic Changes Sensor, which is a parameter that describes the capacity of different indexes to detect induced changes. Traditional indexes at specific time locations (ST level, T wave amplitude and position, and durations of QT interval and QRS complex) and global indexes (based on the Karhunen-Loève transform as applied to the QRS complex, ST-T complex, ST segment and T wave) have been considered. The global indexes better detected ischemic changes than the traditional indexes. The most sensitive were the index for the ST-T complex (89%) in the Karhunen-Loève transform-derived group and for the ST level (61%) in the traditional group. Changes in the ventricular repolarization period usually appeared earlier (77% of patients) than changes in the depolarization period (23% of patients). A similar percentage of patients exhibited the earliest ischemic changes in the T wave (41%) and in the ST segment (36%). The evolution of the Ischemic Changes Sensor parameters showed that the majority (60%) of the total changes occurred during the first minute of occlusion. The results suggest that the use of global electrocardiogram indexes better reflect ischemic changes than do traditional indexes, such as the ST segment deviation.
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| 8. |
- Martinez, J P, et al.
(författare)
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Accuracy of QT Measurement in the EASI-derived 12-lead ECG
- 2006
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Ingår i: Conference proceedings (IEEE Engineering in Medicine and Biology Society. Conf.). - 1557-170X. ; 1, s. 3986-3989
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study is to assess QT interval measurements from the EASI 12-lead ECG as compared to the standard 12-lead ECG. The QT interval was automatically measured in simultaneously recorded standard and EASI 12- lead ECGs, using a validated wavelet-based delineator. The agreement between the two sets of measurements was quantified both on a lead-by-lead basis and a multilead basis. The results show an acceptable agreement between QT measurements in the two lead systems, with correlation coefficients (CC) 0.91-0.98 depending on the lead. Standard deviations range from 9.2 ms to 26.4 ms depending on the selected lead. In a few patients large inter-system differences were found, mainly due to different T wave morphologies. Using a multilead delineation, QT intervals were considerably more stable than single-lead measurements and resulted in a much better agreement between the two lead systems (CC: 0.98, QT difference: 1.1 ms ± 9.8 ms). Thus, EASI-derived 12- lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.
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| 9. |
- Pignot, G., et al.
(författare)
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L’Ischémie n’est pas un facteur d’insuffisance rénale chronique après néphrectomie partielle sur rein unique
- 2014
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Ingår i: Progrès en urologie (Paris). - : Elsevier. - 1166-7087. ; 24:13, s. 822-822
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Tidskriftsartikel (refereegranskat)abstract
- Objectifs Déterminer l‘influence du clampage pédiculaire et de sa durée sur la fonction rénale à long terme après néphrectomie partielle (NP) pour cancer sur rein unique.Méthodes L’étude a inclus rétrospectivement 259 patients opérés par NP entre 1979 et 2010 dans 13 centres. L’utilisation d’un clampage, son type (pédiculaire ou parenchymateux), sa durée ainsi que les données pré-, intra- et postopératoires ont été recueillies. Les valeurs de débit de filtration glomérulaire (DFG) préopératoire et au dernier suivi ont été comparés. Une analyse multivariée selon le modèle de Cox a été réalisée afin de déterminer l’impact de l’ischémie sur le risque d’insuffisance rénale (IR) chronique postopératoire.Résultats La taille moyenne des tumeurs était de 4,0±2,3cm et le DFG préopératoire moyen de 60,8±18,9ml/min. Au total, 106 patients ont été opérés en ischémie chaude (40,9 %) et 53 en ischémie froide (20,5 %). Trente patients (11,6 %) ont évolué vers l’insuffisance rénale chronique. En analyse multivariée, ni le clampage pédiculaire (p=0,44), ni la durée d’ischémie chaude (p=0,1) n’étaient associés à une évolution vers l’insuffisance rénale. Les facteurs indépendants d’insuffisance rénale à long terme étaient le DFG préopératoire (p<0,0001) et les pertes sanguines (p=0,02).Conclusion La fonction rénale après NP sur rein unique apparaît principalement liée à des facteurs non modifiables et notamment le DFG préopératoire. Ce travail relativise l’importance du clampage pédiculaire et du temps d’ischémie qui n’étaient pas significativement liés au risque d’IR dans notre étude.
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| 10. |
- Smith, Danny, et al.
(författare)
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Heart Rate Turbulence Detection Using Mean Shape Information
- 2009
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Ingår i: CINC: 2009 36th Annual Computers in Cardiology Conference. - 0276-6574. ; , s. 153-156
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Konferensbidrag (refereegranskat)abstract
- In this study, we propose a generalized likelihood ratio test statistic for detection of heart rate turbulence (HRT) based on a linear signal model. The new test statistic, which expands our previous original detector; takes a priori information regarding HRT shape into account. The detector structure is based on the extended integral pulse frequency modulation model which accounts for the presence of ectopic beats and HRT The spectral relationship between heart rate variability (HRV) and HRT is investigated for the purpose of modeling HRV "noise" present during the turbulence period. The performance was studied for both simulated data and real data obtained from the Long-Term ST database. The results show that the new detector is superior to the original one as well as to the commonly used parameter turbulence slope (TS) on both types of data.
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| 11. |
- Verhoest, G, et al.
(författare)
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Predictive factors of chronic kidney disease stage V after partial nephrectomy in a solitary kidney : a multi-institutional study
- 2014
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Ingår i: Urologic Oncology. - : Elsevier. - 1078-1439 .- 1873-2496. ; 32:1, s. 28.e21-28.e26
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Partial Nephrectomy (PN) in a solitary kidney is at risk of chronic kidney disease (CKD) stage V and/or haemodialysis (HD). Our objective was to determine predictive factors of CKD stage V in this population. MATERIAL & METHODS: Data from 300 patients were retrospectively collected from 16 tertiary centres. Clinical and operative parameters, tumor characteristics and renal function before surgery were analyzed. Patients with and without CKD stage V (defined as MDRD<15ml/min) were compared using χ2 and Student-t tests for qualitative and quantitative variables, respectively. Predictive factors of CKD stage V were evaluated with a multivariable analysis using a Cox regression model. RESULTS: Median age and BMI were 63 years old and 26kg/m², respectively. Most of the patients (65%) were male with an anatomic solitary kidney (88.3%). Median tumor size was 4cm and 98% were malignant tumors. Median operative time, blood loss and clamping time were 180min, 350ml and 20min respectively. Renal cooling was used in 19.3% and clamping of the pedicle was performed in 61.6%. Twenty five patients (8.5%) presented post operative CKD stage V at last follow-up and 18 underwent HD (6%) post-operatively because of acute renal insufficiency. There was no difference between CKD stage V and non CKD stage V patients concerning Charlson index, operative time (180min vs 179min, p= 0.39), blood loss (475ml vs 350ml, p= 0.51), use of renal cooling and type of clamping. Patients with CKD stage V were older (70 vs 63 years old, p= 0.005), had a lower baseline renal function (clearance MDRD 41 vs. 62ml/min, p<0.0001) and an increased tumor size (p= 0.02). Complications occurred in 91 patients (30%) with 16% of minor (Clavien 1-2) and 14% of major (Clavien>2) complications, respectively. In multivariable analysis, baseline MDRD, BMI, and the occurrence of a minor complication were independent predictive factors of post operative CKD stage V. CONCLUSION: PN in a solitary kidney is at risk of post-operative CKD stage V and HD. Pre-operative altered renal function and post operative complications are the main predictive factors of permanent CKD stage V.
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| 12. |
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| 13. |
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| 14. |
- Albers, P, et al.
(författare)
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Guidelines on testicular cancer
- 2005
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Ingår i: European urology. - : Elsevier BV. - 0302-2838. ; 48:6, s. 885-894
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Tidskriftsartikel (refereegranskat)
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| 15. |
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| 16. |
- Bailon, R, et al.
(författare)
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A robust method for ECG-Based estimation of the respiratory frequency during stress testing
- 2006
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 53:7, s. 1273-1285
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Tidskriftsartikel (refereegranskat)abstract
- A robust method is presented for electrocardiogram (ECG)-based estimation of the respiratory frequency during stress testing. Such ECGs contain highly nonstationary noise and exhibit changes in QRS morphology which, when combined with the dynamic nature of the respiratory frequency, make most existing methods break down. The present method exploits the oscillatory pattern of the rotation angles of the heart's electrical axis as induced by respiration. The series of rotation angles, obtained from least-squares loop alignment, is subject to power spectral analysis and estimation of the respiratory frequency. Robust techniques are introduced to handle the nonstationary properties of exercise ECGs. The method is evaluated by means of both simulated signals, and ECG/airflow signals recorded from 14 volunteers and 20 patients during stress testing. The resulting respiratory frequency estimation error is, for simulated signals, equal to 0.5% +/- 0.2%, mean SD (0.002 +/- 0.001 Hz), whereas the error between respiratory frequencies of the ECG-derived method and the airflow signals is 5.9 % +/- 4 % (0.022 +/- 0.016 Hz). The results suggest that the method is highly suitable for analysis of noisy ECG signals recorded during stress testing.
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| 17. |
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| 18. |
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| 19. |
- Garcia, J., et al.
(författare)
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Automatic detection of ST-T complex changes on the ECG using filtered RMS difference series: application to ambulatory ischemia monitoring
- 2000
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2531 .- 0018-9294. ; 47:9, s. 1195-1201
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Tidskriftsartikel (refereegranskat)abstract
- A new detector is presented which finds changes in the repolarization phase (ST-T complex) of the cardiac cycle. It operates by applying a detection algorithm to the filtered root mean square (rms) series of differences between the beat segment (ST segment or ST-T complex) and an average pattern segment. The detector has been validated using the European ST-T database, which contains ST-T complex episodes manually annotated by cardiologists, resulting in sensitivity/positive predictivity of 85/86%, and 85/76%, for ST segment deviations and ST-T complex changes, respectively. The proposed detector has a performance similar to those which have a more complicated structure. The detector has the advantage of finding both ST segment deviations and entire ST-T complex changes thereby providing a wider characterization of the potential ischemic events. A post-processing stage, based on a cross-correlation analysis for the episodes in the rms series, is presented. With this stage subclinical events with repetitive pattern were found in around 20% of the recordings and improved the performance to 90/85%, and 89/76%, for ST segment and ST-T complex changes, respectively.
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| 20. |
- Garcia, J, et al.
(författare)
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ECG-based detection of body position changes in ischemia monitoring
- 2003
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 50:6, s. 677-685
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this gaper is to analyze and detect changes in body position (BPC) during electrocardiogram (ECG) recording. These changes are often manifested as shifts in the, electrical axis and may be misclassified as ischemic changes during. ambulatory monitoring. We investigate two ECG signal processing methods for detecting BPCs. Different schemes for feature extraction are used (spatial and scalar), while preprocessing, trend postprocessing and detection are identical. The spatial approach is based on VCG loop rotation angles and the scalar approach is based on the Karhunen-Loeve transform (KLT) coefficients. The methods are evaluated on two different databases: a database with annotated BPCs and the STAFF III database with recordings from rest and during angioplasty-induced ischemia but not including BPCs. The angle-based detector results in performance values of detection probability P-D = 95%, false alarm probability P-F = 3% in the BPC database and false alarm rate in the STAFF III database in control ECCs during rest R-F(c) = 2 h(-1) (episodes per hour) and in ischemia recordings during angioplasty R-F(a) = 7 h(-1), whereas the KLT-based detector produces values of P-D = 89%, P-F = 3%, R-F(c) = 4 h(-1), and RF(a) = 11 h-1, respectively. Including information on noise level in the detection process to reduce the number of false alarms, performance values of P-D similar or equal to 90%, P-F similar or equal to 1%, R-F(c) similar or equal to 1 h(-1) and R-F(a) similar or equal to 2 h(-1) are obtained with both methods. It is concluded that reliable detection of BPCs may be achieved using the ECG signal and should work in parallel to ischemia detectors.
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| 21. |
- Garcia, J, et al.
(författare)
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Remote processing server for ECG-based clinical diagnosis support
- 2002
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Ingår i: IEEE Transactions on Information Technology in Biomedicine. - 1089-7771. ; 6:4, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the development of a remote server that provides a user-friendly access to advanced electrocardiographic (ECG) signal processing techniques. The prototype supplies telemedicine facilities to doctors for clinical indexes remote computation to support diagnosis through the Internet. The user-friendly interface is based on the selection of the desired ECG signal processing tools on a Web browser window. The centralized structure of the system permits unique and user-independent update and management of the software and, therefore, is especially suitable for remote or rural regions to have access to the new ECG information techniques.
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| 22. |
- Gil, E., et al.
(författare)
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Detection of heart rate turbulence in photoplethysmographic signals
- 2011
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Ingår i: 2011 Computing in Cardiology. - 9781457706127 - 9781457706110 ; 38, s. 665-668
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Konferensbidrag (refereegranskat)abstract
- In this study, alterations in the cardiovascular system caused by ventricular premature beats (VPBs) are investigated by analyzing the photoplethysmographic (PPG) signal. A simple algorithm for PPG-based detection of VPBs is devised and evaluated, and then employed for the analysis of heart rate turbulence (HRT), here labelled "pulse rate turbulence" (PRT). The pulse transit time is also studied as it constitutes the main difference between HRT and PRT. The data sets included a total of 3872 VPBs and 13169 normal beats. The results showed that VPBs can be detected from the PPG signal with a sensitivity of 92.8%, a specificity of 99.8% and an accuracy of 99.3%, using six features and a simple linear classifier. The shape of PRT was found to resemble that of HRT, the latter type of turbulence resulting from ECG-based analysis, suggesting that PRT analysis can be used as a replacement for HRT analysis when the ECG is not available.
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| 23. |
- Gravas, S, et al.
(författare)
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Seeking evidence that cell kill guided thermotherapy gives results not inferior to those of transurethral prostate resection: Results of a pooled analysis of 3 studies of feedback transurethral microwave thermotherapy
- 2005
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Ingår i: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3792 .- 0022-5347. ; 174:3, s. 1002-1006
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We compared ProstaLund Feedback Treatment(R) (PLFT(R)) to transurethral prostate resection (TURP) in terms of efficacy and safety in a pooled analysis of 3 clinical studies with 1-year followup. Materials and Methods: Overall raw data on 183 patients with PLFT(R) and 65 with TURP were pooled. All studies had identical inclusion criteria, and the efficacy and safety of the method were evaluated using the International Prostate Symptom Score, maximum urine flow (Qmax), responder rate, bother score, prostate volume reduction and adverse events. Results: The response rate was 85.3% and 85.9% in the PLFT(R) and TURP groups, respectively. One-sided 95% CI analysis showed the noninferiority of PLFT(R) vs TURP for this variable. Mean International Prostate Symptom Score was significantly decreased in the PLFT(R) and TURP groups after 12 months (from 20.9 to 6.4 and 20.7 to 7.1, respectively). The 1-sided upper 95% CI of PLFT(R) was within the noninferiority definition compared with that of TURP. The bother score decrease in the PLFT(R) and TURP groups was not significant different (70.9% and 64.0%, respectively). An increase in Qmax from 7.7 to 16.1 ml per second 12 months after PLFT(R) was noted, while the improvement in Qmax in the TURP group was higher (from 7.5 to 18.6 ml per second). The 1-sided lower 95% CI was close (0.76) but it did not attain the predetermined level of noninferiority (0.80). Mean transurethral ultrasound determined volume 12 months after PLFT(R) and TURP was reduced by 32.8% and 58.1%, respectively. A significant correlation between the transurethral ultrasound determined prostate volume reduction and estimated cell kill was found (r = 0.456, p <0.000001). Serious adverse events with causality occurred in 15.4% of patients with TURP compared with 6.0% in those with PLFT(R) (p = 0.035). Conclusions: Combined experience from our pooled analysis indicates that PLFT(R) challenges TURP in terms of efficacy and safety after 1 year of followup.
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| 24. |
- Hernando, D., et al.
(författare)
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Heart rate variability during hemodialysis and its relation to hypotension
- 2011
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Ingår i: Computing in Cardiology 2011, CinC 2011. - 9781457706127 ; 38, s. 189-192
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Konferensbidrag (refereegranskat)abstract
- Acute hypotensive episodes are common during dialysis sessions, and represent a serious problem. Spectral analysis of heart rate variability (HRV) and barorrefle x sensitivity (BRS) is performed to study the behaviour of the autonomic nervous system (ANS) during the hemodialysis. The ratio between the low frequency (LF) and high frequency (HF) power of HRV, as well as BRS in the HF band, are significantly different in patients being prone and resistant to hypotension (p<0.001 and p<0.05, respectively). Moreover, a very low frequency (VLF) modulation visible in HRV, blood pressure and the series of rotation angles of the heart's electrical axis have been studied. It turns out that the VLF component is more pronounced and with higher coherence in prone patients (p<0.05), suggesting a possible relation with altered or imbalanced ANS regulation.
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| 25. |
- Hernando, D, et al.
(författare)
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Identification of patients prone to hypotension during hemodialysis based on the analysis of cardiovascular signals.
- 2015
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Ingår i: Medical Engineering & Physics. - : Elsevier BV. - 1873-4030 .- 1350-4533. ; 37:12, s. 1156-1161
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Tidskriftsartikel (refereegranskat)abstract
- Intradialytic hypotension (IDH) is a major complication during hemodialysis treatment, and therefore it is highly desirable to identify, at an early stage during treatment, whether the patient is prone to IDH. Heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS) were analyzed during the first 30 min of treatment to assess information on the autonomic nervous system. Using the sequential floating forward selection method and linear classification, the set of features with the best discriminative power was selected, resulting in an accuracy of 92.1%. Using a classifier based on the HRV features only, thereby avoiding that continuous blood pressure has to be recorded, accuracy decreased to 90.2%. The results suggest that an HRV-based classifier is useful for determining whether a patient is prone to IDH at the beginning of the treatment.
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| 26. |
- Hoffstaedt, J. P., et al.
(författare)
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System model development and numerical simulation of low-head pumped hydro storage
- 2022
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Ingår i: Trends in Renewable Energies Offshore. - London : CRC Press. - 9781003360773 ; , s. 757-763
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Konferensbidrag (refereegranskat)abstract
- To tackle the growing demand for grid-scale energy storage, the ALPHEUS project proposes a novel low-head pumped hydro storage system aimed for coastal application in countries where the topography does not allow for traditional high-head storage. This system consists of a reversible pump-turbine technology with two contra-rotating runners coupled to their respective axial-flux motor-generators as well as a dedicated control, optimising for energy balancing and the provision of ancillary services. To better understand the integration and dynamic interaction of the individual components of the plant and to allow for the simulation of a wide variety of operating conditions and scenarios, this research aims at developing a system model coupling the hydraulic, mechanical and electrical components. Numerical results are compared and verified based on CFD simulations. While some inaccuracies have to be expected, the comparison shows an overall good match with only minor deviations in dynamic behaviour and steady state results.
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| 27. |
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| 28. |
- Kaiser, K, et al.
(författare)
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WNT5A is transported via lipoprotein particles in the cerebrospinal fluid to regulate hindbrain morphogenesis
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 1498-
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Tidskriftsartikel (refereegranskat)abstract
- WNTs are lipid-modified proteins that control multiple functions in development and disease via short- and long-range signaling. However, it is unclear how these hydrophobic molecules spread over long distances in the mammalian brain. Here we show that WNT5A is produced by the choroid plexus (ChP) of the developing hindbrain, but not the telencephalon, in both mouse and human. Since the ChP produces and secretes the cerebrospinal fluid (CSF), we examine the presence of WNT5A in the CSF and find that it is associated with lipoprotein particles rather than exosomes. Moreover, since the CSF flows along the apical surface of hindbrain progenitors not expressing Wnt5a, we examined whether deletion of Wnt5a in the ChP controls their function and find that cerebellar morphogenesis is impaired. Our study thus identifies the CSF as a route and lipoprotein particles as a vehicle for long-range transport of biologically active WNT in the central nervous system.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Laguna, P., et al.
(författare)
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Sampling rate and the estimation of ensamble variability for repetive signals
- 2000
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Ingår i: Medical & Biological Engineering & Computing. - 0140-0118. ; 38:5, s. 540-546
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of ensemble variability in time-aligned event signals is studied in relation to sampling rate requirements. The theoretical analysis is based on statistical modelling of time misalignment in which the time resolution is limited by the length of the sampling interval. For different signal-to-noise ratios (SNRs), the sampling rate is derived which limits the misalignment effect to less than 10% of the noise effect. Each signal is assumed to be corrupted by additive noise. Using a normal QRS complex with a high SNR (≈ 30 dB), a sampling rate of approximately 3 kHz is needed for accurate ensemble variability measurements. This result is surprising since it implies that the Nyquist rate is far too low for accurate variability measurements. The theoretical results are supplemented with results obtained from an ECG database of 94 subjects for which the ensemble variability is computed at different sampling rates using signal interpolation. The ensemble variability is substantially reduced (40%) when increasing the rate from 1 to 3 kHz, thus corroborating the results suggested by the theoretical analysis.
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| 34. |
- Martínez Cortés, Juan Pablo, et al.
(författare)
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Risk stratification in congestive heart failure patients using a model-based approach to heart rate turbulence characterization
- 2009
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Ingår i: Computers in Cardiology 2009, CinC 2009. - 9781424472819 ; 36, s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Heart rate turbulence (HRT) is commonly assessed by two parameters: turbulence onset (TO) and turbulence slope (TS), both obtained by averaging RR tachograms following a ventricular premature beat (VPB). It has been recently shown that a model-based detection-theoretical approach results in HRT indices outperforming TO/TS in identifying the presence or absence of HRT. The aim of this work is to evaluate the risk stratification ability of this approach, as compared with the classical parameters TO and TS, in a population of 96 ischemic patients with mild to moderate congestive heart failure. We found signifi-cant differences (Mann-Withney U test) between survivors and cardiac death groups for TS and the new parameter TΣ(x). Survival analysis showed that TΣ(x) is the HRT index with highest association to risk of cardiac death (hazard ratio=2.8, p =0.008). Results show improved risk stratification of the new description of HRT with respect to classical parameters.
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| 35. |
- Olmos, S, et al.
(författare)
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Block adaptive filters with deterministic reference inputs for event-related signals: BLMS and BRLS
- 2002
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Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X. ; 50:5, s. 1102-1112
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Tidskriftsartikel (refereegranskat)abstract
- Adaptive estimation of the linear coefficient vector in truncated expansions is considered for the purpose of modeling noisy, recurrent signals. Two different criteria are studied for block-wise processing of the signal: the mean square error (MSE) and the least squares (LS) error. The block LMS (BLMS) algorithm, being the solution of the steepest descent strategy for minimizing the MSE, is shown to be steady-state unbiased and with a lower variance than the LMS algorithm. It is demonstrated that BLMS is equivalent to an exponential averager in the subspace spanned by the truncated set of basis functions. The block recursive least squares (BRLS) solution is shown to be equivalent to the BLMS algorithm with a decreasing step size. The BRLS is unbiased at any occurrence number of the signal and has the same steady-state variance as the BLMS but with a lower variance at the transient stage. The estimation methods can be interpreted in terms of linear, time-variant filtering. The performance of the methods is studied on an ECG signal, and the results show that the performance of the block algorithms is superior to that of the LMS algorithm. In addition, measurements with clinical interest are found to be more robustly estimated in noisy signals.
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| 36. |
- Pueyo, E, et al.
(författare)
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Time course of ECG depolarization and repolarization changes during ischemia in PTCA recordings
- 2004
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Ingår i: Methods of Information in Medicine. - 0026-1270. ; 43:1, s. 43-46
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: In this work we studied the temporal evolution of changes in the electrocardiogram (ECG) as a consequence of the induced ischemia during prolonged coronary angioplasty, comparing the time course of indexes reflecting depolarization and those reflecting repolarization. Methods: We considered both local (measured at specific points of the ECG) and global (obtained from the Karhunen-Loeve transform) indexes. In particular, the evolution of Q, R and S wave amplitudes during ischemia was analyzed with respect to classical indexes such as ST level. As a measurement of sensitivity we used an Ischemic Changes Sensor (ICS), which reflects the capacity of an index to detect changes in the ECG. Results: The results showed that, in leads with low-amplitude ST-T complexes, the S wave amplitude was more sensitive in detecting ischemia than was the commonly used index ST60. It was found that in such leads the S wave amplitude initially exhibited a delayed response to ischemia when compared to ST60, but its performance was better from the second minute of occlusion. The global indexes describing the ST-T complex were, in terms of the ICS, superior to the S wave amplitude for ischemia detection. Conclusions: Ischemic ECG changes occur both at repolarization and depolarization, with alterations in the depolarization period appearing later in time. Local indexes are less sensitive to ischemia than global ones.
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| 37. |
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| 38. |
- Solem, Kristian, et al.
(författare)
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An efficient method for handling ectopic beats using the heart timing signal
- 2006
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 53:1, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- The problem of analyzing heart rate variability in the presence of ectopic beats is revisited. Based on the integral pulse frequency modulation model and the closely related heart timing signal, a new technique is introduced which corrects for the occasional presence of ectopic beats. The correction technique, which involves the occurrence times of a certain number of beats preceding the ectopic beat, is computationally very efficient. From actual heart rate data, the results show that the new technique is associated with a much lower computational complexity (flops reduced by a factor of about 3000) than the original heart timing technique, while producing similar performance. It is also shown that the power spectrum and related clinical indices obtained by the new technique are more accurately estimated than by other methods.
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| 39. |
- Sörnmo, Leif, et al.
(författare)
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El procesado de señales en medicina
- 2007
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Ingår i: Procesado de señales biomédicas. - 9788484275411 ; , s. 7-26
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 40. |
- Sörnmo, Leif, et al.
(författare)
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Electrocardiogram (ECG) Signal Processing
- 2006
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Ingår i: Wiley encyclopedia of biomedical engineering. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9780471249672 ; 2, s. 1298-1313
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Signal processing of electrocardiographic signals has a long and rich history and has greatly helped to enhance the diagnostic capability, especially when signals are recorded in noisy environments. This article gives an introductory presentation of the basic set of algorithms used for conditioning the ECG with respect to different types of noise and artifacts, detecting heartbeats, extracting basic ECG measurements, and performing data compression. Signal processing in clinical applications is exemplified by the high-resolution ECG and T wave alternans.
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| 41. |
- Sörnmo, Leif, et al.
(författare)
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Variablidad del ritmo cardíaco
- 2007
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Ingår i: Procesado de señales biomédicas. - 9788484275411 ; , s. 27-56
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 42. |
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| 43. |
- Åström, Magnus, et al.
(författare)
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Detection of body position changes using the surface electrocardiogram
- 2003
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Ingår i: Medical & Biological Engineering & Computing. - 0140-0118. ; 41:2, s. 164-171
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Tidskriftsartikel (refereegranskat)abstract
- A method for detecting body position changes that uses the surface vectorcardiogram (VCG) is presented. Such changes are often manifested as sudden shifts in the electrical axis of the heart and can erroneously be interpreted as acute ischaemic events. Axis shifts were detected by analysing the rotation angles obtained from the alignment of successive VCG loops to a reference loop. Following the rejection of angles originating from noise events, the detection of body position changes was performed on the angle series using a Bayesian approach. On a database of ECG recordings from normal subjects performing a predefined sequence of body position changes, a detection rate of 92% and a false alarm rate of 7% was achieved.
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| 44. |
- Åström, Magnus, et al.
(författare)
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Vectorcardiographic lop alignment and the measurement of morphologic beat-to-beat variability in noisy signals
- 2000
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2531 .- 0018-9294. ; 47:4, s. 497-506
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of subtle morphologic beat-to-beat variability in the electrocardiogram (ECG)/vectorcardiogram (VCG) is complicated by the presence of noise which is caused by, e.g., respiration and muscular activity. A method was recently presented which reduces the influence of such noise by performing spatial and temporal alignment of VCG loops. The alignment is performed in terms of scaling, rotation and time synchronization of the loops. Using an ECG simulation model based on propagation of action potentials in cardiac tissue, the ability of the method to separate morphologic variability of physiological origin from respiratory activity was studied. Morphologic variability was created by introducing a random variation in action potential propagation between different compartments. The results indicate that the separation of these two activities can be done accurately at low to moderate noise levels (less than 10 microV). At high noise levels, the estimation of the rotation angles was found to break down in an abrupt manner. It was also shown that the breakdown noise level is strongly dependent on loop morphology; a planar loop corresponds to a lower breakdown noise level than does a nonplanar loop.
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