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Physiological Measurement

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https://www.readbyqxmd.com/read/29329110/prediction-of-sustained-harmonic-walking-in-the-free-living-environment-using-raw-accelerometry-data
#1
Jacek Krzysztof Urbanek, Vadim Zipunnikov, Tamara B Harris, William Fadel, Nancy W Glynn, Annemarie Koster, Paolo Caserotti, Ciprian M Crainiceanu, Jaroslaw Harezlak
Using raw, sub-second level, accelerometry data, we propose and validate a method for identifying and characterizing walking in the free-living environment. We focus on the sustained harmonic walking (SHW), which we define as walking for at least 10 seconds with low variability of step frequency. Approach. We utilize the harmonic nature of SHW and quantify local periodicity of the tri-axial raw accelerometry data. We also estimate fundamental frequency of observed signals and link it to the instantaneous walking (step-to-step) frequency (IWF)...
January 12, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29328060/-i-in-vivo-i-neutron-activation-analysis-of-bone-manganese-in-workers
#2
Yingzi Liu, Danelle Rolle-McFarland, Farshad Mostafaei, Yuanzhong Zhou, Yan Li, Wei Zheng, Ellen Wells, Linda Huiling Nie
Manganese (Mn) is a neurotoxicant. However, the impact of elevated, chronic Mn exposure is not well understood, partially due to the lack of a cumulative exposure biomarker. To address this gap, our group developed a compact <i>in vivo</i> neutron activation analysis (IVNAA) system to quantify Mn in bone (MnBn). In this study, we used this system and determined MnBn among male Chinese workers and compared results to their blood Mn (MnB), a measure of recent exposure, and the years of employment, a measure of cumulative exposure...
January 12, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29303488/small-intestinal-ischemia-and-reperfusion-bioimpedance-measurements
#3
Runar James Strand-Amundsen, Christian Tronstad, Havard Kalvoy, Tom Erik Ruud, Jan Olav Hogetveit, Orjan Grottem Martinsen, Tor Inge Tønnessen
Trans-intestinal bioimpedance measurements have previously been used to investigate changes in electrical parameters during 6 hours of ischemia in the small intestine. Knowledge is lacking regarding the time course of trans-intestinal bioimpedance parameters during reperfusion. As reperfusion is an important part in the clinical treatment of intestinal ischemia, we need to know how it affects the bioimpedance measurements. Approach: We performed bioimpedance measurements, using a two-electrode setup on selected segments of the jejunum in 15 pigs...
January 5, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29303486/hearts-during-ischemia-with-or-without-htk-protection-analysed-by-dielectric-spectroscopy
#4
Michael Schaefer, Wolfgang Gross, Martha-Maria Gebhard
We investigated canine hearts during ischemia after aortic cross clamping (UI, n=20) and after HTK-cardioplegia (HTK, n=24) at 35°C, 25°C, 15°C, and 5°C with the aim to compare tissue changes caused by the activity of anaerobic metabolism(AAM), cell membrane destruction(CD), and gap junction uncoupling(GJU). We measured continuously the complex dielectric spectrum(DS), ATP- and lactate content, extracellular pH, and rigor contracture. To identify changes in DS caused by AAM, CD, and GJU we performed additional experiments on the gap junction-free skeletal muscle...
January 5, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29286004/areas-under-peripheral-pulse-waves-a-potential-marker-of-atherosclerotic-changes
#5
Mikko Peltokangas, Jarmo Verho, Ville M Mattila, Pekka Romsi, Antti Vehkaoja, Jukka Lekkala, Niku Oksala
OBJECTIVE: In this study, we propose a method for finding atherosclerotic changes based on the ratios of areas under peripheral arterial pulse wave (PW) contours and analyze its performance. APPROACH: The PW signals were recorded with force sensors and photoplethysmographic sensors from ankle, wrist, cubital fossa, index finger and second toe from 30 atherosclerotic patients and 52 control subjects. In addition, day-to-day repeatability of the method was studied with 10 test subjects examined on 3 different days...
December 29, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29319536/new-photoplethysmogram-indicators-for-improving-cuffless-and-continuous-blood-pressure-estimation-accuracy
#6
Wan-Hua Lin, Hui Wang, Oluwarotimi Williams Samuel, Gengxing Liu, Zhen Huang, Guanglin Li
Objective: The accuracy of cuffless and continuous blood pressure (BP) estimation has been improved, but it is still unsatisfactory for clinical uses. This study was designed to further increase BP estimation accuracy. Approach: In this study, a number of new indicators were extracted from photoplethysmogram (PPG) recordings and linear regression method was used to construct BP estimation models based on the PPG indicators and pulse transit time (PTT). The performance of the BP estimation models was evaluated by the PPG recordings from 22 subjects when they performed mental arithmetic stress and Valsalva's manoeuvre tasks that could induce BP fluctuations...
December 28, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29283360/the-influence-of-dilution-on-the-offline-measurement-of-exhaled-nitric-oxide
#7
Victoria MacBean, Dharmika Pooranampillai, Catherine Howard, Alan Charles Lunt, Anne Greenough
Measurement of fractional exhaled nitric oxide (FeNO) is used to determine the presence and severity of eosinophilic airway inflammation in asthma and other wheezing illnesses. The gold standard of online measurement during a single prolonged exhalation is not suitable for use in young children. The international guidelines for offline measurements recommend collection of exhaled gas in an appropriate reservoir for later analysis in young children. The apparatus required for gas collection, however, creates dead space within the system, which may result in sample dilution and hence inaccuracy...
December 28, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29271359/a-realistic-pelvic-phantom-for-electrical-impedance-measurement
#8
Eoghan Dunne, Brian McGinley, Martin O'Halloran, Emily Porter
To design and fabricate an anatomically and conductively accurate phantom for electrical impedance studies of non-invasive bladder volume monitoring. Approach: A modular pelvic phantom was designed and fabricated, consisting of a mechanically and conductively stable boundary wall, a background medium, and bladder phantoms. The wall and bladders are made of conductive polyurethane. The background material is an ultrasound gel-based mixture, with conductivity matched to a weighted average of the pelvic cavity organs, bone, muscle and fat...
December 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29271352/noninvasive-mapping-reveals-recurrent-and-suddenly-changing-patterns-in-atrial-fibrillation-a-magnetocardiographic-study
#9
Ville Mäntynen, Mika Lehto, Hannu Parikka, Juha Montonen
To study noninvasive magnetocardiographic (MCG) mapping of ongoing atrial fibrillation (AF) and, for possible mapping patterns observed, to develop simplified but meaningful descriptors or parameters, providing a possible basis for future research and clinical use of the mappings. Approach: MCG mapping with simultaneous ECG was recorded during arrhythmia in patients representing a range of typical, clinically classical atrial arrhythmias. The recordings were assessed using MCG map animations and a method to compute magnetic field orientation (MFO) and its time course was created to facilitate presentation of the findings...
December 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29271351/validity-and-reliability-of-smartphone-orientation-measurement-to-quantify-dynamic-balance-function
#10
Nikita A Kuznetsov, Rebecca K Robins, Benjamin Long, Jason T Jakiela, F Jay Haran, Scott E Ross, W Geoff Wright, Christopher K Rhea
OBJECTIVE: Postural control is frequently compromised after sub-concussive and concussive head trauma and balance testing is an integral part of neuromotor assessment and management. The main objective of this paper is to develop a novel smartphone-based neuromotor assessment protocol for screening of dynamic balance decrements stemming from head trauma. APPROACH: Experiments 1 and 2 compared Android smartphone orientation detection algorithms to a biomechanics laboratory motion capture system using a pendulum (i...
December 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29244028/adaptive-heart-rate-based-epileptic-seizure-detection-using-real-time-user-feedback
#11
Thomas De Cooman, Troels Wesenberg Kjær, Sabine Van Huffel, Helge Bjarup Dissing Sørensen
Automated seizure detection in a home environment has been of increased interest the last couple of decades. Heart rate-based seizure detection is a way to detect temporal lobe epilepsy seizures at home, but patient-independent algorithms showed to be insufficiently accurate due to the high patient-dependency of heart rate features. Therefore a real-time adaptive seizure detection algorithm is proposed here. The algorithm starts as a patient-independent algorithm, but gradually converges towards a patient-specific algorithm while more patient-specific data becomes available on-the-run...
December 15, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29239860/reference-intervals-for-the-evoked-tympanic-membrane-displacement-measurement-a-non-invasive-measure-of-intracranial-pressure
#12
Cherith M Campbell-Bell, Anthony A Birch, Dario Vignali, Diederik O Bulters, Robert J Marchbanks
OBJECTIVE Evoked tympanic membrane displacement (TMD) is a non-invasive technique for assessing intracranial pressure (ICP). The aim of this study was to define reference intervals (RIs) in the healthy population. Approach Measurements were made in 154 healthy adults. Results were quantified by Vm which is the most frequently described TMD measurement. Distributions were determined for sitting and supine posture. Differences between right and left ears were explored using a Wilcoxon signed-rank test...
December 14, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29231185/quantitative-evaluation-of-graded-hindlimb-ischemia-based-on-pharmacokinetic-modelling-and-hemodynamic-analysis-of-indocyanine-green
#13
Wenjuan Cai, Yongshuai Li, Fei Liu, Jianwen Luo
OBJECTIVE: Accurate evaluation of the degree of hindlimb ischemia is challenging but essential for the diagnosis and treatment of peripheral vascular insufficiency. The aim of the study is to apply a multiparametric method for the quantitative estimation of mouse models with different degrees of hindlimb ischemia based on a dynamic fluorescence imaging-based strategy. APPROACH: An adjustable hydraulic occluder was placed around the thigh root of one hindlimb to induce six different degrees of hindlimb ischemia...
December 12, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29231181/automatic-two-channel-sleep-staging-using-a-predictor-corrector-method
#14
Shirin Riazy, Tilo Wendler, Juergen Pilz
We developed and implemented two predictor-corrector methods for the classification of two-channel EEG data into sleep stages. Approach: The sequence of sleep stages over the night is modeled by a Markov chain of first and second order, resulting in an informative prior distribution for the new state given the distribution of the current one. The correction step is realized by applying a Bayes classifier using the (preprocessed) data and this prior. The preprocessing step consists of a frequency analysis, a log transformation and a dimensionality reduction via principle component analysis...
December 12, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29227278/an-automated-method-for-dynamic-red-blood-cell-aggregate-detection-in-microfluidic-flow
#15
Rym Mehri, Erfan Niazi, Catherine Mavriplis, Marianne Fenech
Red blood cell (RBC) aggregation is a unique phenomenon that occurs when red blood cells are subjected to low shear rates. Little is known about the sizes, shapes and behaviour of aggregates flowing in healthy humans. However, excessive aggregation has been shown to be an indication of pathological conditions. Therefore, characterizing RBC aggregates is important to medical research. The objective of this study was to develop a reliable technique based on image processing to assess and characterize human RBC aggregation subjected to controlled and measurable shear rates in a two-fluid flow microfluidic shearing system...
December 11, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29206109/methodological-considerations-in-the-calculation-of-the-rate-of-force-development-scaling-factor
#16
Dusica Djordjevic, Mehmet Uygur
OBJECTIVE: Within this methodological study, we aimed to explore the effects of seven different commonly applied routines for rate of force development (RFD) calculation on the calculation of rate of force development scaling factor (RFD-SF) and r2 and the between session reliability of RFD-SF in three different muscle groups. APPROACH: We tested grip force muscles, elbow extensors and knee extensors of 13 healthy subjects asking them to produce around 120 rapid isometric force pulses per muscle to varying submaximal amplitudes...
December 5, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29205172/a-data-driven-approach-for-addressing-the-lack-of-flow-waveform-data-in-studies-of-cerebral-arterial-flow-in-older-adults
#17
Michael J Durka, Isaac Hong Wong, David F Kallmes, Dario Pasalic, Fernando Mut, Manoj Jagani, Pablo J Blanco, Juan R Cebral, Anne M Robertson
Blood flow waveforms - essential data for hemodynamic modeling - are often in practice unavailable to researchers. The objectives of this work were to assess the variability among the waveforms for a clinically relevant older population, and develop data-based methods for addressing the missing waveform data for hemodynamic studies. Approach: We analyzed 272 flow waveforms from the internal carotid arteries of older patients (73±13 years) with moderate cardiovascular disease, and used these data to develop approaches to guide new approaches for hemodynamic studies...
December 5, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29192891/comparison-of-different-functional-eit-approaches-to-quantify-tidal-ventilation-distribution
#18
Zhanqi Zhao, Po-Jen Yun, Yen-Liang Kuo, Feng Fu, Meng Dai, Inez Frerichs, Knut Moeller
The aim of the study was to examine the pros and cons of different types of functional EIT (fEIT) to quantify tidal ventilation distribution in a clinical setting. Approach: fEIT images were calculated with (1) standard deviation of pixel time curve, (2) regression coefficients of global and local impedance time curves, or (3) mean tidal variations. To characterize temporal heterogeneity of tidal ventilation distribution, another fEIT image of pixel inspiration times is also proposed. Main results: fEIT - regression is very robust to signals with different phase information...
December 1, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29185994/linear-and-nonlinear-features-of-fetal-heart-rate-on-the-assessment-of-fetal-development-in-the-course-of-pregnancy-and-the-impact-of-fetal-gender
#19
Kyriaki Spyridou, Ioanna Chouvarda, Leontios J Hadjileontiadis, Nic Maglaveras
OBJECTIVE: This work aims to investigate the impact of gestational age and fetal gender on fetal heart rate (FHR) tracings. STUDY DESIGN: Different linear and non-linear parameters indicating correlation or complexity were used to study the influence of fetal age and gender on FHR tracings. The signals were recorded from 99 normal pregnant women in a singleton pregnancy at gestational age from 28 to 40 weeks, before the onset of labor. 56 of the fetuses were female and 43 were male...
November 29, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29176040/characteristic-impedance-frequency-or-time-domain-approach
#20
Muhammad Umar Qureshi, Mitchel Colebank, David Schreier, Diana Marcela Tabima Martinez, Mansoor A Haider, Naomi C Chesler, Mette S Olufsen
Characteristic impedance (Zc) is an important component in the theory of hemodynamics. It is a commonly used metric of proximal arterial stiffness and pulse wave velocity. Calculated using simultaneously measured dynamic pressure and flow data, estimates of Zc can be obtained using methods based on frequency or time domain analysis. Applications of these methods under different physiological and pathological conditions in species with different body sizes and heart rates show that the two approaches do not always yield the same result...
November 27, 2017: Physiological Measurement
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