Novel heart rate variability index for wrist-worn wearable devices subject to motion artifacts that complicate measurement of the continuous pulse interval
Objective : Wearable health monitoring devices have recently become popular, but they can still only measure the average heart rate. Heart rate variability (HRV) is known to represent changes in the autonomic nervous system and analysis of HRV has the potential to be used for monitoring various wellness-related parameters such as sleep or stress. HRV analysis requires accurate measurement of the heartbeat interval. In wearable devices, it is difficult to accurately measure the heartbeat interval due to motion noise. In this paper we propose a new method for performing HRV analysis on photoplethysmographic (PPG) signa...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Hyun Jae Baek and Jaegeol Cho Source Type: research

Phase entropy: a new complexity measure for heart rate variability
Objective : Information entropy is generally employed for analysing the complexity of physiological signals. However, most definitions of entropy estimate the degree of compressibility and thus quantify the randomness. Physiological signals are very complex because of nonlinear relationships and interactions between various systems and subsystems of the body. Therefore, analysis of randomness may not be sufficient to describe this complexity. To analyse the complexity of heart rate variability (HRV), a new entropy method, phase entropy (PhEn), has been proposed as a quantification of two-dimensional phase space. Appr...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Ashish Rohila and Ambalika Sharma Source Type: research

Non-invasive measurements of respiratory system mechanical properties by the forced oscillation technique in spontaneously breathing, mixed-breed, normal term lambs from birth to five months of age
Objective : To provide a non-invasive approach to monitoring lung function in spontaneously breathing lambs, from birth to five months of life, by the forced oscillation technique (FOT). This report describes the experimental set-up, data processing, and identification of normal predicted values of resistance (Rrs) and reactance (Xrs) of the respiratory system, along with normal bronchodilator response for bronchial reversibility testing. Approach : Rrs and Xrs at 5, 11, and 19 Hz were measured monthly for five months in 20 normal term lambs that breathed spontaneously. In seven lambs, repeated measurements also were...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Chiara Veneroni, Mar Janna Dahl, Anna Lavizzari, Elaine Dawson, Andrew Rebentisch, Sean Studstill, Sydney Bowen, Kurt H Albertine and Raffaele L Dellaca Source Type: research

Focus on Recent Advances in Electrical Impedance Tomography
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Richard Bayford and Nick Polydorides Source Type: research

Sleep quality of subjects with and without sleep-disordered breathing based on the cyclic alternating pattern rate estimation from single-lead ECG
Objective : The term sleep quality is widely used by researchers and clinicians despite the lack of a definitional consensus, due to different assumptions on quality quantification. It is usually assessed using subject self-reporting, a method that has a major limitation since the subject is a poor self-observer of their sleep behaviors. A more precise method requires the estimation of physiological signals through polysomnography, a procedure that has high costs, is uncomfortable for the subjects and it is unavailable to a large group of the world population. To address these issues, a sleep quality prediction metho...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: F ábio Mendonça, Sheikh Shanawaz Mostafa, Fernando Morgado-Dias, Antonio G Ravelo-García and Thomas Penzel Source Type: research

Correlation of bioimpedance changes after compressive loading of murine tissues in vivo
Objective : Rises in the incidence of pressure ulcers are increasingly prevalent in an aging population. Pressure ulcers are painful, are associated with increased morbidity and mortality, increase the risk for secondary infections and inpatient stay, and adds $26.8 billion annually to the healthcare costs of the USA. Evidence suggests that a change in the bioimpedance of living tissue in response to continuous local contact pressure can be a useful indicator for the onset of pressure injuries. Approach : Thirty-five Sprague Dawley rats were subjected to various skin pressures for differing periods of time via a surg...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Joshua R Harvey, Devdip Sen, Angel Baez, Kelli Hickle, Heather Tessier, Robert Slamin, Raymond Dunn, John McNeill and Yitzhak Mendelson Source Type: research

A dictionary learning approach for spatio-temporal characterization of absence seizures
Objective : This research explores absence seizures using data recorded from different layers of somatosensory cortex of four genetic absence epilepsy rats from Strasbourg (GAERS). Localizing the active layers of somatosensory cortex (spatial analysis) and investigating the dynamics of recorded seizures (temporal analysis) are the main goals of this research. Approach : We model the spike discharges of seizures using a generative spatio-temporal model. We assume that there are some states under first-order Markovian model during seizures, and each spike is generated when the corresponding state is activated. We also ...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: S Akhavan, R Phlypo, H Soltanian-Zadeh, M Kamarei and C Jutten Source Type: research

Modification of the mechanical cardiac performance during end-expiratory voluntary apnea recorded with ballistocardiography and seismocardiography
Objective : To assess if micro-accelerometers and gyroscopes may provide useful information for the detection of breathing disturbances in further studies. Approach : Forty-three healthy volunteers performed a 10  s end-expiratory breath-hold, while ballistocardiograph (BCG) and seismocardiograph (SCG) determined changes in kinetic energy and its integral over time ( i K, J · s). BCG measures overall body accelerations in response to blood mass ejection into the main vasculature at each cardiac cycle, while SCG records local chest wall vibrations generated beat-by-beat by myocardial activity. This minim...
Source: Physiological Measurement - November 4, 2019 Category: Physiology Authors: Sofia Morra, Amin Hossein, Damien Gorlier, J érémy Rabineau, Martin Chaumont, Pierre-François Migeotte and Philippe van de Borne Source Type: research

Assessment of ventricular repolarization instability in terms of T-wave alternans induced by head-down bed-rest immobilization
Objective : To assess the effects of different durations of simulated microgravity exposure on ventricular repolarization (VR) in terms of T-wave alternans (TWA) as well as to test whether an increase in VR heterogeneity could be detected once normal gravity was restored. Approach : A total of 63 healthy volunteers were recruited in several head-down bed-rest (HDBR) experiments in the context of the European Space Agency bed-rest strategy. TWA is evaluated during the night period using ambulatory ECG recordings, before, during and after long- (60 d), mid- (21 d) and short- (5 d) duration HDBR by the long-term averagi...
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: Alba Mart ín-Yebra, Violeta Monasterio, Federica Landreani, Pablo Laguna, Juan Pablo Martínez and Enrico G Caiani Source Type: research

Heart sound classification using the SNMFNet classifier
Objective : Heart sound classification still suffers from the challenges involved in achieving high accuracy in the case of small samples. Dimension reduction attempts to extract low-dimensional features with more discriminability from high-dimensional spaces or raw data, and is popular in learning predictive models that target small sample problems. However, it can also be harmful to classification, because any reduction has the potential to lose information containing category attributes. Approach : For this, a novel SNMFNet classifier is designed to directly associate the dimension reduction process with the class...
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: Wei Han, Shengli Xie, Zuyuan Yang, Songbin Zhou and Haonan Huang Source Type: research

Testing heart rate asymmetry in long, nonstationary 24 hour RR-interval time series
Objective : Heart rate asymmetry is a phenomenon in which the contribution of heart rate decelerations to short-term heart rate variability is greater than that of accelerations, and the contribution of accelerations to long-term and total variability is greater than that of decelerations. This has been established for short, stationary recordings, so our aim is to do it for long recordings. Approach : In this paper, we analyze heart rate asymmetry in 87 long, 24  h electrocardiogram Holter recordings from healthy people. We show that in the whole recording all types of asymmetry are observable, clear and high...
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: J Piskorski, J Ellert, T Krauze, W Grabowski, A Wykretowicz and P Guzik Source Type: research

First magnetic particle imaging angiography in human-sized organs by employing a multimodal ex vivo pig kidney perfusion system
Objective : Magnetic particle imaging (MPI) is a new, fast 3D imaging technique, which is considered promising for angiographies. As available MPI scanners suffer from restricted spatial resolution and are mostly constructed for small animal imaging, no vessels within one organ have been depicted by MPI, yet. The purpose of this study was to develop an ex vivo organ perfusion system to display vessels within one organ of human size by MPI and to compare the results to an established 3D imaging technique. Approach : An ex vivo porcine kidney perfusion system compatible with digital subtraction angiography (DSA), magne...
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: I Molwitz, H Ittrich, T Knopp, T Mummert, J Salamon, C Jung, G Adam and M G Kaul Source Type: research

Changes in electrolyte concentrations alter the impedance during ischemia-reperfusion injury in rat brain
In this study, changes in the bio-impedance spectroscopy using a two-electrode method with varying frequencies from 100 to 35  kHz have been assessed in a model of global cerebral ischemia in anesthetized rats during normal, occlusion and reperfusion conditions. Global cerebral ischemia was induced by bilateral common carotid artery occlusion for 40  min following 40 min of reperfusion. The concentration of sodium, potassium, calcium and chloride ions in the whole rat brain was determined by electrolyte analyzer. For the interpretation of in vivo results, changes in electrical impedance with vary...
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: Gaurav Kumar, Uvanesh Kasiviswanathan, Sumedha Mukherjee, Sanjeev Kumar Mahto, Neeraj Sharma and Ranjana Patnaik Source Type: research

Focus collection on Thermal Imaging in Medicine
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - October 30, 2019 Category: Physiology Authors: Graham Machin, Kevin Howell, John Allen and Rob Simpson Source Type: research

Smart alarms towards optimizing patient ventilation in intensive care: the driving pressure case
Objective : Alarms are a substantial part of clinical practice, warning clinicians of patient complications. In this paper, we focus on alarms in the intensive care unit and especially on the use of machine learning techniques for the creation of alarms for the ventilator support of patients. The aim is to study a method to enable timely interventions for intubated patients and prevent complications induced by high driving pressure ( ΔP) and lung strain during mechanical ventilation. Approach : The relation between the ΔP and the total set of the ventilator parameters was examined and resulted in a predic...
Source: Physiological Measurement - October 13, 2019 Category: Physiology Authors: Elisavet Koutsiana, Achilleas Chytas, Katerina Vaporidi and Ioanna Chouvarda Source Type: research

Effect of sampling rate on acceleration and counts of hip- and wrist-worn ActiGraph accelerometers in children
Sampling rate (Hz) of ActiGraph accelerometers may affect processing of acceleration to activity counts when using a hip-worn monitor, but research is needed to quantify if sampling rate affects actual acceleration (mgs), when using wrist-worn accelerometers and during non-locomotive activities. Objective : To assess the effect of ActiGraph sampling rate on total counts/15  s and mean acceleration and to compare differences due to sampling rate between accelerometer wear locations and across different types of activities. Approach : Children ( n   =  29) wore a hip- and wrist-worn a...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Kimberly A Clevenger, Karin A Pfeiffer, Kelly A Mackintosh, Melitta A McNarry, Jan Br ønd, Daniel Arvidsson and Alexander H K Montoye Source Type: research

Bilateral assessment of body core temperature through axillar, tympanic and inner canthi thermometers in a young population
There are several sites in which the human body core temperature can be estimated and used to identify febrile states in a threat of pandemic situations at high-populational-traffic places (e.g. airports, ports, universities, schools, public buildings). In these locations, a fast method is required for temperature screening of masses. The most common methods are axillar and tympanic thermometers. However, in addition, measurement of the inner canthi (IC) of the eye with infrared thermal (IRT) imaging has been suggested as a fast mass measurement screening tool. Objective : It is the aim of this research to identify t...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Ricardo Vardasca, Carolina Magalhaes, Diana Marques, Joana Moreira, Rita Frade, Aderito Seixas, Joaquim Mendes and Francis Ring Source Type: research

Monitoring breathing rate by fusing the physiological impact of respiration on video-photoplethysmogram with head movements
Objective : The simple observation of breathing rate (BR) remains the first and often the most sensitive marker of acute respiratory dysfunction. In fact, there is evidence that drastic changes in BR are a predictive indicator of adverse events (i.e. cardiac arrest). The aim of this study is to develop a camera-based technology that may provide near-continuous estimation of BR considering the effect of respiration on video-PPG (vPPG). Approach : The technology has been tested in two different experimental settings, including controlled BR and more challenging scenarios with spontaneous breathing patterns. Video data ...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Luca Iozza, Jes ús Lázaro, Luca Cerina, Davide Silvestri, Luca Mainardi, Pablo Laguna and Eduardo Gil Source Type: research

Influence of reconstruction settings in electrical impedance tomography on figures of merit and physiological parameters
Objective : Electrical impedance tomography (EIT) is a non-invasive and relatively cheap imaging technique allowing continuous monitoring of lung function at the bedside. However, image reconstruction and processing are not yet standardized for clinical use, limiting comparability and reproducibility between studies. In addition, optimal reconstruction settings still have to be identified for different clinical applications. In this work (i) a systematic way to select ‘good’ EIT algorithm parameters is developed and (ii) an evaluation of these parameters in terms of correct functional imaging and consiste...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: F Th ürk, M Elenkov, A D Waldmann, S Böhme, C Braun, A Adler and E Kaniusas Source Type: research

A computationally efficient algorithm to obtain an accurate and interpretable model of the effect of circadian rhythm on resting heart rate
Objective : Wrist-worn wearable devices equipped with heart rate (HR) sensors have become increasingly popular. The ability to correctly interpret the collected data is fundamental to analyse user ’s well-being and perform early detection of abnormal physiological data. Circadian rhythm is a strong factor of variability in HR, yet few models attempt to accurately model its effect on HR. Approach : In this paper we present a mathematical derivation of the single-component cosinor model with multiple components that fits user data to a predetermined arbitrary function (the expected shape of the circadian effect o...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Davide Morelli, Leonardo Bartoloni, Alessio Rossi and David A Clifton Source Type: research

Is the motor unit mean firing rate versus recruitment threshold relationship linear?
Advances in surface electromyographic (EMG) signal decomposition allow researchers to analyze data for 20 –50 motor units per contraction. To simplify interpretation, some investigators rely on group mean analysis of the mean firing rate versus recruitment threshold relationship, but it is unclear if this association is linear. Objective : To determine whether this relationship is strongest when analyzed via linear, quadratic, or cubic regression. Approach : Twenty-one men (mean   ±  SD age   =  24  ±  4 years) and ...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Kylie K Harmon, Ryan M Girts, Rob J MacLennan and Matt S Stock Source Type: research

Validity of Mobility Lab (version 2) for gait assessment in young adults, older adults and Parkinson ’s disease
Objective : Gait provides a sensitive measurement for signs of aging and neurodegenerative conditions. Measurement of gait is transitioning from the laboratory environment to the clinic with the use of inertial measurement units, providing a simple and cost-effective assessment tool. However, such assessments first need validation against reference systems. The aim of this study was to validate the APDM Mobility Lab (ML) system (version 2) against a pressure sensor walkway in younger adults ( n   =  18), older adults ( n   =  18) and people with mild Parkinson&rs...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Rosie Morris, Samuel Stuart, Grace McBarron, Peter C Fino, Martina Mancini and Carolin Curtze Source Type: research

A strategy combining intrinsic time-scale decomposition and a feedforward neural network for automatic seizure detection
Epilepsy is a common neurological disorder which can occur in people of all ages globally. For the clinical treatment of epileptic patients, the detection of epileptic seizures is of great significance. Objective : Electroencephalography (EEG) is an essential component in the diagnosis of epileptic seizures, from which brain surgeons can detect important pathological information about patient epileptiform discharges. This paper focuses on adaptive seizure detection from EEG recordings. We propose a new feature extraction model based on an adaptive decomposition method, named intrinsic time-scale decomposition (ITD), ...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Lijun Yang, Sijia Ding, Hao-min Zhou and Xiaohui Yang Source Type: research

Validity, reliability, and feasibility of the uSense activity monitor to register physical activity and gait performance in habitual settings of geriatric patients
Objective : The aim of the study was to investigate the psychometric quality of a newly developed activity monitor (uSense) to document established physical activity parameters as well as innovative qualitative and quantitative gait characteristics in geriatric patients. Approach : Construct and concurrent validity, test-retest reliability, and feasibility of established as well as innovative characteristics for qualitative gait analysis were analyzed in multi-morbid, geriatric patients with cognitive impairment (CI) ( n   =  110), recently discharged from geriatric rehabilitation. Main re...
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Martin Bongartz, Rainer Kiss, Andr é Lacroix, Tobias Eckert, Phoebe Ullrich, Carl-Philipp Jansen, Manuel Feißt, Sabato Mellone, Lorenzo Chiari, Clemens Becker and Klaus Hauer Source Type: research

Focus collection on Modern Approaches for Sports Medicine and Performance
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - September 29, 2019 Category: Physiology Authors: Samuel Stuart, William Johnston, Brian Caulfield and Alan Godfrey Source Type: research

On the suitability of laser-Doppler flowmetry for capturing microvascular blood flow dynamics from darkly pigmented skin
Objective : To assess the performance of laser Doppler flowmetry (LDF) in measuring blood perfusion from darkly-pigmented skin, i.e. skin with high melanin concentration. LDF provides for the noninvasive monitoring of microvascular blood flow dynamics. It has been used extensively on light-skinned subjects, i.e. on skin with low melanin concentration, in both the healthy and pathological states. Because the optical properties of human skin might affect the reliability of optically-based diagnostic equipment, the effectiveness of LDF needs to be checked and evaluated on dark skin, too, if this method is to be useful i...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Yunus A Abdulhameed, Gemma Lancaster, Peter V E McClintock and Aneta Stefanovska Source Type: research

Thoracic EIT in 3D: experiences and recommendations
Objective : In EIT applications to the thorax, a single electrode plane has typically been used to reconstruct a transverse 2D ‘slice’. However, such images can be misleading as EIT is sensitive to contrasts above and below the electrode plane, and ventilation and aeration inhomogeneities can be distributed in complex ways. Using two (or more) electrode planes, 3D EIT images may be reconstructed, but 3D reconstructions are currently little used in thoracic EIT. In this paper, we investigate an incremental pathway towards 3D EIT reconstructions, using two electrode planes to calculate improved transverse s...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Bart łomiej Grychtol, Johannes Peter Schramel, Fabian Braun, Thomas Riedel, Ulrike Auer, Martina Mosing, Christina Braun, Andreas D Waldmann, Stephan H Böhm and Andy Adler Source Type: research

Relationship between skin temperature and soft tissue hardness in diabetic patients: an exploratory study
This study intends to analyse an eventual association between skin temperature and soft tissue hardness in the foot of diabetic patients Approach : Twenty diabetic patients enrolled for this study. The analysis was done at the foot level, therefore, skin temperature and soft tissue hardness data of the plantar surface of 40 feet were obtained in eight regions of the foot, two in the heel, two in the midfoot, three in the forefoot and one in the hallux. Information regarding glycaemic control (HbA1c levels) was retrieved from the clinical records of the patients. Main results : After averaging skin temperature and sof...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Ad érito Seixas, Kurt Ammer, Rui Carvalho, João Paulo Vilas-Boas, Joaquim Mendes and Ricardo Vardasca Source Type: research

Determination of bone sodium (Na) and Na exchange in pig leg using in vivo neutron activation analysis (IVNAA)
Objective : The locations of sodium (Na) storage and its exchange mechanisms in the body are not well known. Understanding tissue Na storage and exchange is important for understanding the impact of Na intake, absorption, and retention on human health, especially on the risk of developing chronic diseases. The purpose of this study was to investigate the application of a deuterium –deuterium (DD) neutron generator-based IVNAA system in Na nutrition studies. Approach : The right legs of two live pigs, one on a low Na diet and one on a high Na diet, both for 14 d, were irradiated inside a customized irradiation c...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Mychaela D Coyne, Andrea Lobene, Colby Neumann, Pamela Lachcik, Connie M Weaver and Linda H Nie Source Type: research

Computer analysis of histopathological images for tumor grading. 2
Objective : We have upgraded our own original color filtration pixel-by-pixel (CFPP) method (Klonowski et al 2018a Physiol. Meas . 39 034002) to enable not only automatic and rapid assessment of the proliferation index of a tumor or neoplasm but also quick automatic location of hot-spots (regions of interest, ROIs) in immunohistochemically stained microscopic images of neoplasms and tumors. Approach : Neoplastic cells stain differently from normal cells. By counting in a given window the number of pixels belonging to the given subspaces of (R,G,B) color space which correspond, respectively, to proliferating cells (wh...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Wlodzimierz Klonowski, Anna Korzynska and Aneta Chwala Source Type: research

Reference database and performance evaluation of methods for extraction of atrial fibrillatory waves in the ECG
This study proposes a reference database, composed of a large number of simulated ECG signals in atrial fibrillation (AF), for investigating the performance of methods for extraction of atrial fibrillatory waves ( f -waves). Approach : The simulated signals are produced using a recently published and validated model of 12-lead ECGs in AF. The database is composed of eight signal sets together accounting for a wide range of characteristics known to represent major challenges in f -wave extraction, including high heart rates, high morphological QRST variability, and the presence of ventricular premature beats. Each set...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Ra úl Alcaraz, Leif Sörnmo and José J Rieta Source Type: research

Recent development of respiratory rate measurement technologies
Respiratory rate (RR) is an important physiological parameter whose abnormality has been regarded as an important indicator of serious illness. In order to make RR monitoring simple to perform, reliable and accurate, many different methods have been proposed for such automatic monitoring. According to the theory of respiratory rate extraction, methods are categorized into three modalities: extracting RR from other physiological signals, RR measurement based on respiratory movements, and RR measurement based on airflow. The merits and limitations of each method are highlighted and discussed. In addition, current works...
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Haipeng Liu, John Allen, Dingchang Zheng and Fei Chen Source Type: research

Wearables and mHealth in mental health and neurological disorders
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - August 1, 2019 Category: Physiology Authors: Joachim A Behar, Julien Oster, Maarten De Vos and Gari D Clifford Source Type: research

The stationary wavelet transform as an efficient reductor of powerline interference for atrial bipolar electrograms in cardiac electrophysiology
Objective : The most relevant source of signal contamination in the cardiac electrophysiology (EP) laboratory is the ubiquitous powerline interference (PLI). To reduce this perturbation, algorithms including common fixed-bandwidth and adaptive-notch filters have been proposed. Although such methods have proven to add artificial fractionation to intra-atrial electrograms (EGMs), they are still frequently used. However, such morphological alteration can conceal the accurate interpretation of EGMs, specially to evaluate the mechanisms supporting atrial fibrillation (AF), which is the most common cardiac arrhythmia. Give...
Source: Physiological Measurement - July 29, 2019 Category: Physiology Authors: Miguel Mart ínez-Iniesta, Juan Ródenas, José J Rieta and Raúl Alcaraz Source Type: research

Noise-robust bioimpedance approach for cardiac output measurement
Objective : Congestive heart failure is a problem affecting millions of Americans. A continuous, non-invasive, telemonitoring device that can accurately monitor cardiac metrics could greatly help this population, reducing unnecessary hospitalizations and cost . Approach : Machine learning (ML) algorithms trained on electrical-impedance tomography (EIT) data are presented for portable cardiac monitoring. The approach was validated on a simulated thorax and a measured tank experiment. A highly detailed 4D chest model (finite element method mesh and conductivity profiles) was developed utilizing the 4D XCAT phantom to p...
Source: Physiological Measurement - July 29, 2019 Category: Physiology Authors: Ethan K Murphy, Justice Amoh, Saaid H Arshad, Ryan J Halter and Kofi Odame Source Type: research

Improving haemodynamic optimization of cardiac resynchronization therapy for heart failure
Objective : Optimization of cardiac resynchronization therapy using non-invasive haemodynamic parameters produces reliable optima when performed at high atrial paced heart rates. Here we investigate whether this is a result of increased heart rate or atrial pacing itself. Approach : Forty-three patients with cardiac resynchronization therapy underwent haemodynamic optimization of atrioventricular (AV) delay using non-invasive beat-to-beat systolic blood pressure in three states: rest (atrial-sensing, 66   ±  11 bpm), slow atrial pacing (73  ±  12 bp...
Source: Physiological Measurement - April 30, 2019 Category: Physiology Authors: Alexander J Sharp, S M Afzal Sohaib, Matthew J Shun-Shin, Punam Pabari, Keith Willson, Christopher Rajkumar, Alun D Hughes, Prapa Kanagaratnam, Jamil Mayet, Zachary I Whinnett, Andreas A Kyriacou and Darrel P Francis Source Type: research

Bi-frequency symmetry difference electrical impedance tomography —a novel technique for perturbation detection in static scenes
Objective : A novel method for the imaging of static scenes using electrical impedance tomography (EIT) is reported with implementation and validation using numerical and phantom models. The technique is applicable to regions featuring symmetry in the normal case, asymmetry in the presence of a perturbation, and where there is a known, frequency-dependent change in the electrical conductivity of the materials in the region. Approach : The stroke diagnostic problem is used as a motivating sample application. The head is largely symmetrical across the sagittal plane. A haemorrhagic or ischaemic lesion located away from...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Barry McDermott, James Avery, Martin O ’Halloran, Kirill Aristovich and Emily Porter Source Type: research

Can changes in echo intensity be used to detect the presence of acute muscle swelling?
Objective: The purpose of this study was to examine acute changes in muscle thickness (MTH) and echo-intensity (EI), following four sets of biceps curls, when it is known that the change in MTH is due entirely to swelling. Approach: Forty-nine resistance-trained men and women participated in this study. Individuals in the experimental group ( n   =  23) visited the lab on two separate occasions. During the first visit, paperwork and one repetition maximum (1RM) strength were measured. During the second visit (3 –5 d after visit 1), individuals performed four sets of biceps curls to fa...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Noam Yitzchaki, Tayla E Kuehne, J Grant Mouser and Samuel L Buckner Source Type: research

Monitoring the respiratory rate of preterm infants using an ultrathin film sensor embedded in the bedding: a comparative feasibility study
Objective : To determine the feasibility of unobtrusively monitoring the respiratory rate (RR) in preterm infants by using a film-like pressure sensor placed between the mattress and the bedding. Approach : The RR was simultaneously measured by processing the chest impedance (CI) and the ballistographic (BSG) signal acquired from the pressure sensor in 10 preterm infants of varying body weight. Nearly 27  h of data were analyzed from these infants while in different body positions including both spontaneously breathing infants and those receiving non-invasive respiratory support. Main results : The RR acquired...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Rohan Joshi, Bart Bierling, Loe Feijs, Carola van Pul and Peter Andriessen Source Type: research

Application of infrared thermography in diagnosing peripherally inserted central venous catheter infections in children with cancer
The objective of this preliminary study is to use infrared thermography to discern whether there is an infection in patients with a CVC and, if so, to undertake a close follow-up of its evolution, after administering a therapy. Thermal asymmetry by mean and maximum temperatures (temperature affected ROI   −  temperature contralateral ROI) is measured. Main results : In all cases with catheter infection, thermal asymmetry values were higher than in controls without infection, allowing us to assess improvement after starting the treatment. Significance : These preliminary results are s...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: O Benavent Casanova, N Benavente G ómez, J I Priego Quesada, C M Galindo Gonzalez, R M Cibrián Ortiz de Anda, R Salvador Palmero and F Núñez Gómez Source Type: research

Short-term multiscale complexity analysis of cardiovascular variability improves low cardiac output syndrome risk stratification after coronary artery bypass grafting
Background: Low cardiac output syndrome (LCOS) is a myocardial dysfunction leading to systemic hypoperfusion, favored by particular conditions of the autonomic nervous system. LCOS is one of the adverse events that might occur after cardiac surgery. Objective: The aim is to test the hypothesis that short-term multiscale complexity (MSC) analysis of heart period (HP) and systolic arterial pressure (SAP) variability series in the frequency bands typical of cardiovascular control could be fruitfully exploited in identifying subjects at risk of developing LCOS after coronary artery bypass graft (CABG). Approach: HP and S...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Vlasta Bari, Emanuele Vaini, Valeria Pistuddi, Angela Fantinato, Beatrice Cairo, Beatrice De Maria, Marco Ranucci and Alberto Porta Source Type: research

Validation of a velocity-based algorithm to quantify saccades during walking and turning in mild traumatic brain injury and healthy controls
The objective of this study was to validate a velocity-based algorithm for saccade detection in IR eye-tracking raw data during walking (straight ahead and while turning) in people with mTBI and healthy controls. Approach : Eye-tracking via a mobile IR Tobii Pro Glasses 2 eye-tracker (100  Hz) was performed in people with mTBI ( n   =  10) and healthy controls ( n   =  10). Participants completed two walking tasks: straight walking (walking back and forth for 1  min over a 10 m distance), and walking and turning (turns c... (Source: Physiological Measurement)
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Samuel Stuart, Lucy Parrington, Douglas Martini, Bryana Popa, Peter C Fino and Laurie A King Source Type: research

Modelling approach to obtain regional respiratory mechanics using electrical impedance tomography and volume-dependent elastance model
Objective: This paper presents a method for breath-by-breath estimation of regional respiratory mechanics without the need for special manoeuvres (such as inspiratory pause or low-flow inflation) using electrical impedance tomography (EIT) associated with pressure/airflow waveforms. Approach: We developed a method to estimate regional parameters using the regional impedance fraction, by multiplying it by global flow and volume waveforms. A volume-dependent elastance model was used to obtain compliance, resistance, volume-independent ( E 1 ), and volume-dependent ( E 2 ) components. Three swine under invasive mechanic...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: M Victor, J Melo, R Rold án, M Nakamura, M Tucci, E Costa, M Amato, T Yoneyama and H Tanaka Source Type: research

External ankle supports alter running biomechanics: a field-based study using wearable sensors
Objectives : To evaluate the effects of ankle taping, bracing, and fibular reposition taping (FRT) on running biomechanics as measured with wearable sensors. Approach : A randomized crossover study design was employed as 12 young adults (six males, six females) with history of ankle sprain completed four 400 m runs at self-selected pace on an outdoor track. One of four conditions (control, taped, braced, FRT) was applied prior to each run. RunScribe ™ sensors were heel-mounted on each shoe and measured kinematic (maximum pronation velocity, pronation excursion), kinetic (braking and impact g ) and spatiotempora...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: Christopher Gregory, Rachel M Koldenhoven, Michael Higgins and Jay Hertel Source Type: research

Comparing D-bar and common regularization-based methods for electrical impedance tomography
Objective : To compare D-bar difference reconstruction with regularized linear reconstruction in electrical impedance tomography. Approach : A standard regularized linear approach using a Laplacian penalty and the GREIT method for comparison to the D-bar difference images. Simulated data was generated using a circular phantom with small objects, as well as a ‘Pac-Man’ shaped conductivity target. An L-curve method was used for parameter selection in both D-bar and the regularized methods. Main results : We found that the D-bar method had a more position independent point spread function, was less sensitive...
Source: Physiological Measurement - April 25, 2019 Category: Physiology Authors: S J Hamilton, W R B Lionheart and A Adler Source Type: research

An active learning framework for enhancing identification of non-artifactual intracranial pressure waveforms
Objective : Intracranial pressure (ICP) is an important and established clinical measurement that is used in the management of severe acute brain injury. ICP waveforms are usually triphasic and are susceptible to artifact because of transient catheter malfunction or routine patient care. Existing methods for artifact detection include threshold-based, stability-based, or template matching, and result in higher false positives (when there is variability in the ICP waveforms) or higher false negatives (when the ICP waveforms lack complete triphasic components but are valid). Approach : We hypothesized that artifact lab...
Source: Physiological Measurement - January 18, 2019 Category: Physiology Authors: Murad Megjhani, Ayham Alkhachroum, Kalijah Terilli, Jenna Ford, Clio Rubinos, Julie Kromm, Brendan K Wallace, E Sander Connolly, David Roh, Sachin Agarwal, Jan Claassen, Raghav Padmanabhan, Xiao Hu and Soojin Park Source Type: research

Gauging electrical properties of bone with a bioimpedance-sensing drill
This study aims to demonstrate that electrical impedance spectroscopy can be integrated within a standard surgical drill to distinguish between bone types. Approach : A custom bearing and insulated drill bit were designed to collect 10 cortical and cancellous impedance measurements from ex vivo femurs (2 pigs) and 80 bone measurements from in situ femurs (4 pigs). In the in situ study, two return electrodes (simulating a lip-c... (Source: Physiological Measurement)
Source: Physiological Measurement - January 18, 2019 Category: Physiology Authors: Rebecca D Butler and Ryan J Halter Source Type: research

Detecting and interpreting myocardial infarction using fully convolutional neural networks
Objective : We aim to provide an algorithm for the detection of myocardial infarction that operates directly on ECG data without any preprocessing and to investigate its decision criteria. Approach : We train an ensemble of fully convolutional neural networks on the PTB ECG dataset and apply state-of-the-art attribution methods. Main results : Our classifier reaches 93.3% sensitivity and 89.7% specificity evaluated using 10-fold cross-validation with sampling based on patients. The presented method outperforms state-of-the-art approaches and reaches the performance level of human cardiologists for detection of myocar...
Source: Physiological Measurement - January 15, 2019 Category: Physiology Authors: Nils Strodthoff and Claas Strodthoff Source Type: research

Continuous non-invasive determination of nocturnal blood pressure variation using photoplethysmographic pulse wave signals: comparison of pulse propagation time, pulse transit time and RR-interval
Objective : Cardiovascular diseases are the leading cause of death, whereas nocturnal ambulatory blood pressure (BP) is the most potent predictor for cardiovascular risk. The volume clamp and pulse transit time (PTT) are common methods for continuous non-invasive BP measurement, but have drawbacks during unsupervised ambulatory use and undisturbed sleep. The pulse propagation time (PPT), defined as the time between pulse wave systolic peak and diastolic peak, provides valid information about the pressure pulse waveform. However, the use of PPT for nocturnal BP variation determination and whether such variation is aff...
Source: Physiological Measurement - January 11, 2019 Category: Physiology Authors: Christoph Fischer and Thomas Penzel Source Type: research

AF detection from ECG recordings using feature selection, sparse coding, and ensemble learning
The objective of this paper is to provide an algorithm for accurate, automated detection of atrial fibrillation (AF) from ECG signals. Four types of ECG signals are considered: normal signals, signals representing symptoms of AF, other signals, and noisy signals. This paper represents follow-up work to the authors ’ entry in the 2017 PhysioNet Challenge as reported in the 2017 Computing in Cardiology Conference. Approach : Our approach involves extracting features from the ECG waveform and training a machine learning classifier. In feature extraction, we calculate several statistical features related to the ECG...
Source: Physiological Measurement - December 24, 2018 Category: Physiology Authors: Muhammed Rizwan, Bradley M Whitaker and David V Anderson Source Type: research