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Physiological Measurement

Lin Yang, Canhua Xu, Meng Dai, Feng Fu, Xuetao Shi, Xiuzhen Dong
Multi-frequency electrical impedance tomography (MFEIT) reconstructs the image of conductivity inside the human body based on the dependence of tissue conductivity on frequency. As there exist differences in the conductivity over frequency between blood, ischemic cortical tissue and normal cortical tissue, MFEIT has potential application in the detection of acute stroke. However, because the conductivity distribution of the human head is highly inhomogeneous and the conductivities of normal head tissue and stroke lesion tissue both change with frequency, the anomaly and normal head tissues are often mixed together in the reconstructed image, which makes it difficult to discern the anomaly...
November 29, 2016: Physiological Measurement
Guang Li, Tinglin Zhang, Xiaojian Chen, Chungang Shang, You Wang
The difference of brain functional connectivity between hypoxic and normal states was studied. The impact of intermittent hypoxic training on the hypoxia tolerance of the brain was explored. Multivariable empirical mode decomposition was applied to extract common inherent modes of multichannel EEG adaptively instead of a priori selection of filter bandwidth, and the first two scales of intrinsic mode functions expressed the differences in brain connectivity. To quantify synchronization and search for consistent performance, coherence, phase locking value and synchronization likelihood were all utilized...
November 29, 2016: Physiological Measurement
Michael Wininger, Kristie Bjornson
Wearable activity monitors are increasingly prevalent in health research, but there is as yet no data-driven study of artefact removal in datasets collected from typically developing children across childhood. Here, stride count data were collected via a commercially available activity monitor (StepWatch), which employs an internal filter for sub-threshold accelerations, but does not post-process supra-threshold activity data. We observed 428 typically-developing children, ages 2-15, wearing the StepWatch for 5 consecutive days...
November 24, 2016: Physiological Measurement
Carl Shiffman
Precontraction impedance changes (PICs) are known to occur during isometric contractions of the human forearm finger flexors. Without reliance on electroencephalogical data these are construed as evidence for the construction of a 'template of instructions' in the brain for muscle contractions to be performed once a 'go' instruction is received, as widely expected from EEG measurements A model is proposed to explain earlier impedance results, based on a PIC-associated time-dependent inhibitory constraint and a modified role for the 'go' command...
November 24, 2016: Physiological Measurement
E J Meijer, H J Niemarkt, I P P C Raaijmakers, A M Mulder, C van Pul, P F F Wijn, P Andriessen
Brain connectivity is associated with axonal connections between brain structures. Our goal was to quantify the interhemispheric neuronal connectivity in healthy preterm infants by automated quantitative EEG time-correlation analysis. As with advancing postmenstrual age (PMA, gestational age  +  postnatal age) the neuronal connectivity between left and right hemisphere increases, we expect to observe changes in EEG time-correlation with age. Thirty-six appropriate-for-gestational age preterm infants (PMA between 27-37 weeks) and normal neurodevelopmental follow-up at 5 years of age were included...
November 24, 2016: Physiological Measurement
Marco Piola, Riccardo Vismara, Giordano Tasca, Federico Lucherini, Paola Redaelli, Monica Soncini, Claudia Romagnoni, Andrea Mangini, Carlo Antona, Gianfranco Beniamino Fiore
Several novel approaches were recently developed to treat aortic root pathologies. The alteration induced by some of these approaches to the biomechanics of the aortic root could possibly affect the coronary perfusion, compromising the procedural outcome. In this scenario, the need to replicate in vitro the coronary flow pattern in physiological and pathological conditions is becoming crucial for the functional assessment of novel devices and techniques. This article describes the design of an easy-to-use, left-and-right coronary impedance simulator, coupled with native aortic roots for in vitro pulsatile tests...
November 24, 2016: Physiological Measurement
J A M van Scheepen, M P H Koster, B Vasak, C Redman, A Franx, A Georgieva
Phase rectified signal averaging (PRSA) is increasingly used for fetal heart rate (FHR) monitoring, both with traces acquired with external Doppler cardiotocography (D-FHR), and with transabdominal fetal electrocardiography (ta-FHR). However, it is unclear to what extend the acquisition method influences the PRSA analysis, whether results from using one acquisition method are comparable to those based on FHR acquired by the other method, and if not, which should be the preferred method. To address these questions, we applied PRSA analysis to 28 antepartum synchronous recordings of the FHR using simultaneously D-FHR and ta-FHR...
November 24, 2016: Physiological Measurement
Lia C Puder, Silke Wilitzki, Christoph Bührer, Hendrik S Fischer, Gerd Schmalisch
Computerized wheeze detection is an established method for objective assessment of respiratory sounds. In infants, this method has been used to detect subclinical airway obstruction and to monitor treatment effects. The optimal location for the acoustic sensors, however, is unknown. The aim of this study was to evaluate the quality of respiratory sound recordings in young infants, and to determine whether the position of the sensor affected computerized wheeze detection. Respiratory sounds were recorded over the left lateral chest wall and the trachea in 112 sleeping infants (median postmenstrual age: 49 weeks) on 129 test occasions using an automatic wheeze detection device (PulmoTrack(®))...
November 21, 2016: Physiological Measurement
Chengyu Liu, David Springer, Qiao Li, Benjamin Moody, Ricardo Abad Juan, Francisco J Chorro, Francisco Castells, José Millet Roig, Ikaro Silva, Alistair E W Johnson, Zeeshan Syed, Samuel E Schmidt, Chrysa D Papadaniil, Leontios Hadjileontiadis, Hosein Naseri, Ali Moukadem, Alain Dieterlen, Christian Brandt, Hong Tang, Maryam Samieinasab, Mohammad Reza Samieinasab, Reza Sameni, Roger G Mark, Gari D Clifford
In the past few decades, analysis of heart sound signals (i.e. the phonocardiogram or PCG), especially for automated heart sound segmentation and classification, has been widely studied and has been reported to have the potential value to detect pathology accurately in clinical applications. However, comparative analyses of algorithms in the literature have been hindered by the lack of high-quality, rigorously validated, and standardized open databases of heart sound recordings. This paper describes a public heart sound database, assembled for an international competition, the PhysioNet/Computing in Cardiology (CinC) Challenge 2016...
November 21, 2016: Physiological Measurement
Peng Xiong, Hongrui Wang, Ming Liu, Feng Lin, Zengguang Hou, Xiuling Liu
As a primary diagnostic tool for cardiac diseases, electrocardiogram (ECG) signals are often contaminated by various kinds of noise, such as baseline wander, electrode contact noise and motion artifacts. In this paper, we propose a contractive denoising technique to improve the performance of current denoising auto-encoders (DAEs) for ECG signal denoising. Based on the Frobenius norm of the Jacobean matrix for the learned features with respect to the input, we develop a stacked contractive denoising auto-encoder (CDAE) to build a deep neural network (DNN) for noise reduction, which can significantly improve the expression of ECG signals through multi-level feature extraction...
November 21, 2016: Physiological Measurement
Daniel Rafferty, Catriona Dolan, Malcolm Granat
Understanding the contribution that attending a workplace has in accumulating physical activity (PA) may help inform strategies used to increase PA. This study explores the influence that attending work has on the total number of steps taken and the time spent in moderate to vigorous activity (MVPA). A global position system (GPS) was used to identify the geographical domain of the participant. An activity monitor (activPAL, PALtechnologies Ltd, Glasgow, UK) was employed to measure the number of steps taken and the cadence of those steps...
November 14, 2016: Physiological Measurement
Hamza El Hadi, Andrea Frascati, Marnie Granzotto, Valentina Silvestrin, Elisabetta Ferlini, Roberto Vettor, Marco Rossato
Brown adipose tissue (BAT) plays a key role in adaptive thermogenesis in mammals, and it has recently been considered as an attractive therapeutic target for tackling human obesity by increasing energy expenditure. Thermal imaging using infrared thermography (IRT) has emerged as a potential safe, rapid and inexpensive technique for detecting BAT in humans. However, little attention has been given to the reliability of this method in obese subjects. To this end, we evaluated the capacity of IRT to detect activated supraclavicular (SCV) BAT in 14 lean and 16 mildly obese young adults after acute cold exposure...
November 14, 2016: Physiological Measurement
S Sun, R Bezemer, X Long, J Muehlsteff, R M Aarts
In this work, a model to estimate systolic blood pressure (SBP) using photoplethysmography (PPG) and electrocardiography (ECG) is proposed. Data from 19 subjects doing a 40 min exercise was analyzed. Reference SBP was measured at the finger based on the volume-clamp principle. PPG signals were measured at the finger and forehead. After an initialization process for each subject at rest, the model estimated SBP every 30 s for the whole period of exercise. In order to build this model, 18 features were extracted from PPG signals by means of its waveform, first derivative, second derivative, and frequency spectrum...
November 14, 2016: Physiological Measurement
Jakob Orschulik, Rudolf Petkau, Tobias Wartzek, Nadine Hochhausen, Michael Czaplik, Steffen Leonhardt, Daniel Teichmann
Impedance spectroscopy can be used to analyze the dielectric properties of various materials. In the biomedical domain, it is used as bioimpedance spectroscopy (BIS) to analyze the composition of body tissue. Being a non-invasive, real-time capable technique, it is a promising modality, especially in the field of lung monitoring. Unfortunately, up to now, BIS does not provide any regional lung information as the electrodes are usually placed in hand-to-hand or transthoracic configurations. Even though transthoracic electrode configurations are in general capable of monitoring the lung, no focusing to specific regions is achieved...
November 4, 2016: Physiological Measurement
Yichao Zhou, Xiyuan Hu, Zhenmin Tang, Andrew C Ahn
Electrocardiogram (ECG) signal enhancement and QRS complex detection is a critical preprocessing step for further heart disease analysis and diagnosis. In this paper, we propose a sparse representation-based ECG signal enhancement and QRS complex detection algorithm. Unlike traditional Fourier or wavelet transform-based methods, which use fixed bases, the proposed algorithm models the ECG signal as the superposition of a few inner structures plus additive random noise, where these structures (referred to here as atoms) can be learned from the input signal or a training set...
November 4, 2016: Physiological Measurement
Jose Maria Perez-Macias, Jari Viik, Alpo Varri, Sari-Leena Himanen, Mirja Tenhunen
The aim of this study is to explore the capability of an Emfit (electromechanical film transducer) mattress to detect snoring (SN) by analyzing the spectral differences between normal breathing (NB) and SN. Episodes of representative NB and SN of a maximum of 10 min were visually selected for analysis from 33 subjects. To define the bands of interest, we studied the statistical differences in the power spectral density (PSD) between both breathing types. Three bands were selected for further analysis: 6-16 Hz (BW1), 16-30 Hz (BW2) and 60-100 Hz (BW3)...
November 4, 2016: Physiological Measurement
Amadeus Holmer, Florian Tetschke, Jörg Marotz, Hagen Malberg, Wenke Markgraf, Christine Thiele, Axel Kulcke
The monitoring of free flaps, free transplants or organs for transplantation still poses a problem in medicine. Available systems for the measurement of perfusion and oxygenation can only perform localized measurements and usually need contact with the tissue. Contact free hyperspectral imaging and near-infrared spectroscopy (NIRS) for the analysis of tissue oxygenation and perfusion have been used in many scientific studies with good results. But up to now the clinical and scientific application of this technology has been hindered by the lack of hyperspectral measurement systems usable in clinical practice...
October 27, 2016: Physiological Measurement
V MacBean, C Hughes, G Nicol, C C Reilly, G F Rafferty
Neural respiratory drive, quantified by the parasternal intercostal muscle electromyogram (EMGpara), provides a sensitive measure of respiratory system load-capacity balance. Reference values for EMGpara-based measures are lacking and the influence of individual anthropometric characteristics is not known. EMGpara is conventionally expressed as a percentage of that obtained during a maximal inspiratory effort (EMGpara%max), leading to difficulty in applying the technique in subjects unable to reliably perform such manoeuvres...
October 25, 2016: Physiological Measurement
Hasan H Eroğlu, B Murat Eyüboğlu
In this paper, the abilities of injected current magnetic resonance electrical impedance tomography (MREIT) and induced current magnetic resonance electrical impedance tomography (ICMREIT) systems to differentiate a conductivity perturbation from an otherwise uniform conductivity distribution are compared. The sensitivity of MREIT measurements changes as a function of distance to the electrodes used for current injection. The sensitivity of ICMREIT measurements is related to the radial location, being a minimum for concentrically located small conductivity perturbations...
October 24, 2016: Physiological Measurement
Randall Moorman, Maggie Simmons
No abstract text is available yet for this article.
October 18, 2016: Physiological Measurement
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