Vascular ageing and peripheral pulse: an improved model for assessing their relationship
Objective. Vascular ageing is associated with several alterations, including arterial stiffness and
endothelial dysfunction. Such alterations represent an independent factor in the development of
cardiovascular disease (CVD). In our previous works we demonstrated the alterations occurring in the
vascular system are themselves reflected in the shape of the peripheral waveform; thus, a model that
describes the waveform as a sum of Gaussian curves provides a set of parameters that successfully
discriminate between under ( ?35 years old) and over subjects (>35 years old). In the present work,
we explored the feasibility ...
Source: Physiological Measurement - December 29, 2021 Category: Physiology Authors: Cosimo Aliani, Eva Rossi, Piergiorgio Francia and Leonardo Bocchi Source Type: research
A supervised machine learning semantic segmentation approach for detecting artifacts in
plethysmography signals from wearables
The objective
of this study is to develop an effective supervised algorithm to locate the regions of artifacts
within PPG signals. Approach . We treat artifact detection as a 1D segmentation problem. We solve it
via a novel combination of an active-contour-based loss and an adapted U-Net architecture. The
proposed algorithm was trained on the PPG DaLiA training set, and further evaluated on the PPG DaLiA
testing set, WESAD dataset and TROIKA dataset. Main results . We evaluated with the DICE score, a
well-established metric for segmentation accuracy evaluation in the field of computer vision. The
proposed method out...
Source: Physiological Measurement - December 29, 2021 Category: Physiology Authors: Zhicheng Guo, Cheng Ding, Xiao Hu and Cynthia Rudin Source Type: research
From sleep medicine to medicine during sleep
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - December 29, 2021 Category: Physiology Authors: Joachim A Behar, Yosi Shamay, Daniel Álvarez, Félix Del Campo and Thomas Penzel Source Type: research
Spectral analysis of heart sounds associated with coronary artery disease
Objective . The aim of this study was to find spectral differences of diagnostic interest in heart
sound recordings of patients with coronary artery disease (CAD) and healthy subjects. Approach .
Heart sound recordings from three studies were pooled, and patients with clear diagnostic outcomes
(positive: CAD and negative: Non-CAD) were selected for further analysis. Recordings from 1146
patients (191 CAD and 955 Non-CAD) were analyzed for spectral differences between the two groups
using Welch ’s spectral density estimate. Frequency spectra were estimated for systole and diastole
segments, and time-frequency spectr...
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Bjarke Skogstad Larsen, Simon Winther, Louise Nissen, Axel Diederichsen, Morten B øttcher, Johannes Jan Struijk, Mads Græsbøll Christensen and Samuel Emil Schmidt Source Type: research
Automatic cough classification for tuberculosis screening in a real-world environment
We present
experiments based on a dataset of 1358 forced cough recordings obtained in a developing-world clinic
from 16 patients with confirmed active pulmonary TB and 35 patients suffering from respiratory
conditions suggestive of TB but confirmed to be TB negative. Using nested cross-validation, we have
trained and evaluated five machine learning classifiers: logistic regression (LR), support vector
machines, k-nearest neighbour, multilayer perceptrons and convolutional neural networks. Main
Results. Although classification is possible in all cases, the best performance is achieved using
LR. In combination with fe...
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Madhurananda Pahar, Marisa Klopper, Byron Reeve, Rob Warren, Grant Theron and Thomas Niesler Source Type: research
Anatomical atlas of the upper part of the human head for electroencephalography and bioimpedance
applications
The objective of this work is to develop a 4D (3D+T) statistical anatomical atlas of the
electrical properties of the upper part of the human head for cerebral electrophysiology and
bioimpedance applications. Approach. The atlas was constructed based on 3D magnetic resonance images
(MRI) of 107 human individuals and comprises the electrical properties of the main internal
structures and can be adjusted for specific electrical frequencies. T1w+T2w MRI images were used to
segment the main structures of the head while angiography MRI was used to segment the main arteries.
The proposed atlas also comprises a time-varying...
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Fernando S Moura, Roberto G Beraldo, Leonardo A Ferreira and Samuli Siltanen Source Type: research
Single sensor measurement of heel-height during the push-off phase of gait
Objective . In healthy gait a forceful push-off is needed to get an efficient leg swing and
propulsion, and a high heel lift makes a forceful push-off possible. The power of the push-off is
decreased with increased age and in persons with impaired balance and gait. The aim of this study
was to evaluate whether a wearable equipment (Striton) and algorithms to estimate vertical
heel-height during gait from a single optical distance sensor is reliable and feasible for clinical
applications. Approach . To assess heel-height with the Striton system an optical distance sensor
was used to measure the distance to the floor a...
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Tomas B äcklund, Helena Grip, Fredrik Öhberg and Nina Sundström Source Type: research
Video based non-contact monitoring of respiratory rate and chest indrawing in children with
pneumonia
Objective. Pneumonia is the single largest cause of death in children worldwide due to infectious
diseases. According to WHO guidelines, fast breathing and chest indrawing are the key indicators of
pneumonia in children requiring antibiotic treatments. The aim of this study was to develop a video
based novel method for simultaneous monitoring of respiratory rate and chest indrawing without
upsetting babies. Approach. Respiratory signals, corresponding to periodic movements of
chest-abdominal walls during breathing, were extracted by analyzing RGB (red, green, blue)
components in video frames captured by a smartphone ...
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Ferdous Karim Lucy, Khadiza Tun Suha, Sumaiya Tabassum Dipty, Md Sharjis Ibne Wadud and Muhammad Abdul Kadir Source Type: research
Corrigendum: Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive
imaging assessment (2021 Physiol. Meas. 42 [http://doi.org/10.1088/1361-6579/ac18fd] 09TR01 )
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: Aaron M Troy and Hai-Ling Margaret Cheng Source Type: research
Photoplethysmography (PPG): state-of-the-art methods and applications
Description unavailable (Source: Physiological Measurement)
Source: Physiological Measurement - November 29, 2021 Category: Physiology Authors: John Allen, Dingchang Zheng, Panicos A Kyriacou and Mohamed Elgendi Source Type: research
Tensor electrical impedance myography identifies clinically relevant features in amyotrophic lateral
sclerosis
Objective. Electrical impedance myography (EIM) shows promise as an effective biomarker in
amyotrophic lateral sclerosis (ALS). EIM applies multiple input frequencies to characterise muscle
properties, often via multiple electrode configurations. Herein, we assess if non-negative tensor
factorisation (NTF) can provide a framework for identifying clinically relevant features within a
high dimensional EIM dataset. Approach. EIM data were recorded from the tongue of healthy and ALS
diseased individuals. Resistivity and reactivity measurements were made for 14 frequencies, in three
electrode configurations. This gives 84...
Source: Physiological Measurement - November 3, 2021 Category: Physiology Authors: Chl öe N Schooling, T Jamie Healey, Harry E McDonough, Sophie J French, Christopher J McDermott, Pamela J Shaw, Visakan Kadirkamanathan and James J P Alix Source Type: research
Can ionic concentration changes due to mechanical deformation be responsible for the
neurostimulation caused by focused ultrasound? A simulation study
Objective. Ultrasound stimulation is an emerging neuromodulation technique, for which the exact
mechanism of action is still unknown. Despite the number of hypotheses such as mechanosensitive ion
channels and intermembrane cavitation, they fail to explain all of the observed experimental
effects. Here we are investigating the ionic concentration change as a prime mechanism for the
neurostimulation by the ultrasound. Approach. We derive the direct analytical relationship between
the mechanical deformations in the tissue and the electric boundary conditions for the cable theory
equations and solve them for two types of...
Source: Physiological Measurement - November 3, 2021 Category: Physiology Authors: Vladimir Filkin, Igor Kuznetsov, Olga Antonova, Ilya Tarotin, Alexander Nemov and Kirill Aristovich Source Type: research
Comparison of impedance cardiography and cardiac magnetic resonance imaging for the evaluation of
cardiac function in early-stage breast cancer patients
Objective. Breast cancer treatment can negatively impact cardiac function in some breast cancer
patients. Current methods (MUGA, echocardiography) used in clinical practice to detect abnormal
cardiac changes as a result of treatment suffer from important limitations. Use of alternative
techniques that would offer safe, inexpensive and non-invasive cardiac function assessment in this
population would be highly advantageous. The aim of this study was to examine the agreement between
impedance cardiography (ICG) and cardiac magnetic resonance imaging (CMR) in quantifying stroke
volume (SV), cardiac output (CO) and end-d...
Source: Physiological Measurement - November 3, 2021 Category: Physiology Authors: Erifyli Piastopoulou, Parvaiz Ali, Gianfilippo Bertelli, Martyn Heatley, Maung Moe, Chandramohan Murugesan, Gareth Stratton and Michael Lewis Source Type: research
Blood pressure assessment with in-ear photoplethysmography
In this study, we aimed to estimate blood pressure (BP) from in-ear photoplethysmography
(PPG). This novel implementation provided an unobtrusive and steady way of recording PPG, whereas
previous PPG measurements were mostly performed at the wrist, finger, or earlobe. Methods . The time
between forward and reflected PPG waves was very short at the ear site. To minimize errors
introduced by feature extraction, a multi-Gaussian decomposition of in-ear PPG was performed. Both
hand-crafted and whole-based features were extracted and the best combination of features was
selected using a backward-search wrapper method and ...
Source: Physiological Measurement - November 3, 2021 Category: Physiology Authors: Xiaoman Xing, Zhimin Ma, Shengkai Xu, Mingyou Zhang, Wei Zhao, Mingxuan Song and Wen-Fei Dong Source Type: research
Accuracy and applicability of non-invasive evaluation of aortic wave intensity using only pressure
waveforms in humans
Background. Wave intensity (WI) analysis is a well-established method for quantifying the energy
carried in arterial waves, providing valuable clinical information about cardiovascular function.
The primary drawback of this method is the need for concurrent measurements of both pressure and
flow waveforms. Objective . We have for the first time investigated the accuracy of a novel
methodology for estimating wave intensity employing only single pressure waveform measurements; we
studied both carotid- and radial-based estimations in a large heterogeneous cohort. Approach.
Tonometry was performed alongside Doppler ultra...
Source: Physiological Measurement - November 3, 2021 Category: Physiology Authors: Arian Aghilinejad, Faisal Amlani, Jing Liu and Niema M Pahlevan Source Type: research
