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Physiological Measurement

Aodhán Hickey, Eleanor Gunn, Lisa Alcock, Silvia Del Din, Alan Godfrey, Lynn Rochester, Brook Galna
Biomarkers are required to track disease progression and measure the effectiveness of interventions for people with spinocerebellar ataxia type-6 (SCA6). Gait is a potential biomarker that is sensitive to SCA6 which can be measured using wearable technology, reducing the need for expensive specialist facilities. However, algorithms used to calculate gait using data from wearables have not been validated in SCA6. This study sought to examine the validity of a single wearable for deriving 14 spatio-temporal gait characteristics in SCA6 and control cohorts...
October 25, 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
Hadis Biglari, Reza Sameni
Fetal motility is a widely accepted indicator of the well-being of a fetus. In previous research, it has be shown that fetal motion (FM) is coherent with fetal heart rate accelerations and an indicator for active/rest cycles of the fetus. The most common approach for FM and fetal heart rate (FHR) assessment is by Doppler ultrasound (DUS). While DUS is the most common approach for studying the mechanical activities of the heart, noninvasive fetal electrocardiogram (ECG) and magnetocardiogram (MCG) recording and processing techniques have been considered as a possible competitor (or complement) for the DUS...
October 24, 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
Hui Li, Jingbo Li, Xiaohong Zhou, Jianrong Zhao, Fengru Zhang, Liqun Wu, Hong Shen, Qing Wan, Jing Huang, Shungang Yang, Ping Wang
Heart failure patients have a high incidence of chronotropic incompetence (CI) that receives less clinical attention. This study assessed a method using wearable devices to identify CI in heart failure patients. Twenty-six heart failure patients (LVEF: 43.9  ±  5.7% with LVEF  ⩾40% in 19 patients; age: 52.8  ±  12.4 years, female patients  =  6) were enrolled. Each patient underwent symptom-limited treadmill maximal exercise testing during which the simultaneous recording of ECG Holter and physical activity using Actigraph was conducted...
October 18, 2016: Physiological Measurement
Cory M Smith, Terry J Housh, Nathaniel D M Jenkins, Ethan C Hill, Kristen C Cochrane, Amelia A Miramonti, Richard J Schmidt, Glen O Johnson
The purposes of the present study were to apply a unique method for the identification of the time course of changes in neuromuscular responses and to infer the motor unit activation strategies used to maintain force during a fatiguing, intermittent isometric workbout. Eleven men performed 50, 6 s intermittent isometric muscle actions of the leg extensors, each separated by 2 s of rest at 60% maximal voluntary isometric contraction (MVIC). Electromyographic (EMG) and mechanomyographic (MMG) amplitude (root mean square; RMS) and frequency (mean power frequency; MPF) were obtained from the vastus lateralis (VL) every 5 of the 50 repetitions and normalized as a percent of the initial repetition...
October 18, 2016: Physiological Measurement
Amal A Wanigatunga, Paul V Nickerson, Todd M Manini, Parisa Rashidi
The objective of this analysis was to apply symbolic aggregate approximation (SAX) time-series analysis to accelerometer data for activity pattern visualization stratified by self-reported mobility difficulty. A total of 2393 (71.6  ±  7.9 years old) participants wore an accelerometer on the hip (4  +  d; 10  +  h) during the national health and nutrition examination survey (NHANES), a biannual series of health assessments of the US population. One minute epoch data was used to perform SAX, which converted accelerometry time series data into four activity levels...
October 18, 2016: Physiological Measurement
Quan Ding, Yong Bai, Yusuf Bugra Erol, Rebeca Salas-Boni, Xiaorong Zhang, Xiao Hu
QRS peak detection is a challenging problem when ECG signal is corrupted. However, additional physiological signals may also provide information about the QRS position. In this study, we focus on a unique benchmark provided by PhysioNet/Computing in Cardiology Challenge 2014 and Physiological Measurement focus issue: robust detection of heart beats in multimodal data, which aimed to explore robust methods for QRS detection in multimodal physiological signals. A dataset of 200 training and 210 testing records are used, where the testing records are hidden for evaluating the performance only...
October 13, 2016: Physiological Measurement
Mina Taghipour, Golnar Eftekhari, Zahra Haddadian, Roham Mazloom, Mohammad Mani, Ali R Mani
Sepsis, and other causes of acute systemic inflammation, can reduce heart rate variability (HRV) and increase cardiac cycle regularity in mammals. Thus, HRV monitoring has been used for early detection of sepsis in adults and neonates. Liver cirrhosis is associated with reduced basal HRV and the development of tolerance to the cardiac chronotropic effects of bacterial endotoxin. This may pose limitations on the use of heart rate monitoring in early detection of sepsis in this patient population. In a study to develop a physiomarker for the detection of sepsis in cirrhosis, we observed that endotoxin administration in adult cirrhotic rats leads to the development of transient heart rate decelerations, a phenomenon which has been reported in neonates with sepsis, and quantified using sample asymmetry analysis...
October 13, 2016: Physiological Measurement
H K Mohseni, D Cowan, D R Chettle, N D Priest, J Atanackovic, S H Byun, W V Prestwich
The time-dependent behaviour of sodium and chlorine was studied as a spinoff from a study of aluminum in the hand of subjects suffering from Alzheimer's disease and a control group, involving 15 Alzheimer's and 16 control subjects with an age range of 63-89 years. This was achieved using the in vivo neutron activation analysis system developed at McMaster University for the non-invasive measurement of aluminum, where a subject's hand is placed in a beam of accelerator-based thermalized neutrons, which activates elements by neutron capture...
October 6, 2016: Physiological Measurement
Qingxue Zhang, Dian Zhou, Xuan Zeng
This paper proposes a novel machine learning-enabled framework to robustly monitor the instantaneous heart rate (IHR) from wrist-electrocardiography (ECG) signals continuously and heavily corrupted by random motion artifacts in wearable applications. The framework includes two stages, i.e. heartbeat identification and refinement, respectively. In the first stage, an adaptive threshold-based auto-segmentation approach is proposed to select out heartbeat candidates, including the real heartbeats and large amounts of motion-artifact-induced interferential spikes...
September 28, 2016: Physiological Measurement
Luca Iozzia, Luca Cerina, Luca Mainardi
In this paper, classical time- and frequency-domain variability indexes obtained by pulse rate variability (PRV) series extracted from video-photoplethysmography signals (vPPG) were compared with heart rate variability (HRV) parameters extracted from ECG signals. The study focuses on the analysis of the changes observed during a rest-to-stand manoeuvre (a mild sympathetic stimulus) performed on 60 young, normal subjects (age: [Formula: see text] years). The objective is to evaluate if video-derived PRV indexes may replace HRV in the assessment of autonomic responses to external stimulation...
September 28, 2016: Physiological Measurement
Safa Yaghini Bonabi, Fatima El-Hamad, Alexander Müller, Michael Dommasch, Alexander Steger, Georg Schmidt, Mathias Baumert
Beat-to-beat variability of the QT interval (QTV) measured on surface ECG has emerged as a potential marker for ventricular repolarization instability and has been used along with heart rate variability (HRV) to predict arrhythmic risk. Since measurement modalities of QTV have not been standardized, the objective of this study was to investigate the effect of ECG recording duration on QTV as well as HRV. Using a database of 30 min ECG recorded from 500 patients with acute myocardial infraction during rest, we extracted RR and QT interval time series and estimated different HRV and QTV metrics over windows of varying length...
September 28, 2016: Physiological Measurement
Gianfranco Piccirillo, Federica Moscucci, Claudia Fiorucci, Claudia Di Iorio, Fabiola Mastropietri, Damiano Magrì
To seek possible differences in short-period temporal RR interval, P-wave and PR interval dispersion and spectral coherence in patients with a head-up tilt test positive for vasovagal syncope with or without prolonged asystole, severe symptoms and at high risk of trauma. We retrospectively reviewed 5 min ECG and blood pressure recordings obtained at baseline, at rest and during head-up tilt in 40 patients diagnosed as having recurrent vasovagal syncope confirmed at a head-up tilt test. We analysed autoregressive spectral power for all the ECG-derived variables, focusing on temporal P-wave and PR interval dispersion indexes as well as their spectral coherence calculated on the same 5 min recordings at rest and during tilt...
September 28, 2016: Physiological Measurement
Mojtaba Jafari Tadi, Eero Lehtonen, Tero Hurnanen, Juho Koskinen, Jonas Eriksson, Mikko Pänkäälä, Mika Teräs, Tero Koivisto
Heart rate monitoring helps in assessing the functionality and condition of the cardiovascular system. We present a new real-time applicable approach for estimating beat-to-beat time intervals and heart rate in seismocardiograms acquired from a tri-axial microelectromechanical accelerometer. Seismocardiography (SCG) is a non-invasive method for heart monitoring which measures the mechanical activity of the heart. Measuring true beat-to-beat time intervals from SCG could be used for monitoring of the heart rhythm, for heart rate variability analysis and for many other clinical applications...
September 28, 2016: Physiological Measurement
Ben Stansfield, Alex Rowlands, Dinesh John, Sebastien Chastin, Charlotte Edwardson, Maria Hagströmer
No abstract text is available yet for this article.
September 21, 2016: Physiological Measurement
R McCullagh, C Dillon, D Dahly, N F Horgan, S Timmons
Evidence suggests that inactivity during a hospital stay is associated with poor health outcomes in older medical inpatients. We aimed to estimate the associations of average daily step-count (walking) in hospital with physical performance and length of stay in this population. Medical in-patients aged ⩾65 years, premorbidly mobile, with an anticipated length of stay ⩾3 d, were recruited. Measurements included average daily step-count, continuously recorded until discharge, or for a maximum of 7 d (Stepwatch Activity Monitor); co-morbidity (CIRS-G); frailty (SHARE F-I); and baseline and end-of-study physical performance (short physical performance battery)...
September 21, 2016: Physiological Measurement
D M Harrington, C L Edwardson, J Henson, K Khunti, T Yates, M J Davies
How sedentary time (ST) relates to total and regional adiposity and whether these associations are independent of moderate- to vigorous-intensity physical activity (MVPA) are of clinical and public health interest. We assessed the relationship between objectively measured MVPA, ST and ST breaks in adults at risk of type 2 diabetes. The sample consisted of 163 adults (37-75 years) recruited from primary care. Dual energy x-ray absorptiometry (iDXA, GE Corp) was used to estimate total and regional (appendages and trunk) fat mass as well as fat mass in the abdominal (android) and hip/thigh (gynoid) regions...
September 21, 2016: Physiological Measurement
E J Shiroma, M A Schepps, J Harezlak, K Y Chen, C E Matthews, A Koster, P Caserotti, N W Glynn, T B Harris
Accelerometer wear location may influence physical activity estimates. This study investigates this relationship through the examination of activity patterns throughout the day. Participants from the aging research evaluating accelerometry (AREA) study (n men  =  37, n women  =  47, mean age (SD)  =  78.9 (5.5) years) were asked to wear accelerometers in a free-living environment for 7 d at three different wear locations; one on each wrist and one on the right hip. During waking hours, wrist-worn accelerometers consistently produced higher median activity counts, about 5  ×  higher, as well as wider variability compared to hip-worn monitors...
September 21, 2016: Physiological Measurement
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