Analytical solution to Windkessel models using piecewise linear aortic flow waveform
Objective. Deriving time-domain analytical solutions to two- three- and four-element Windkessel models, which are commonly used in teaching and research to analyse the behaviour of the arterial pressure-flow relationship. Approach. The governing (first-order, non-homogeneous, linear) differential equations are solved analytically, based on a piecewise linear function that can accurately approximate typical aortic flow waveforms. Main results. Closed-form expressions for arterial pressure are obtained both in transient conditions and in steady-state periodic regime. Significance. In most cases Windkessel models are studied ...
Source: Physiological Measurement - June 5, 2023 Category: Physiology Authors: Gianni Gnudi Source Type: research
A review of the effect of skin pigmentation on pulse oximeter accuracy
Objective. Pulse oximetry is a non-invasive optical technique used to measure arterial oxygen saturation (SpO2) in a variety of clinical settings and scenarios. Despite being one the most significant technological advances in health monitoring over the last few decades, there have been reports on its various limitations. Recently due to the Covid-19 pandemic, questions about pulse oximeter technology and its accuracy when used in people with different skin pigmentation have resurfaced, and are to be addressed. Approach. This review presents an introduction to the technique of pulse oximetry including its basic principle of...
Source: Physiological Measurement - May 31, 2023 Category: Physiology Authors: Raghda Al-Halawani, Peter H Charlton, Meha Qassem and Panayiotis A Kyriacou Source Type: research
Electrical impedance myography method of measuring anisotropic tongue tissue
Conclusion. Our methodology enables EIM technology to reverse-engineer the anisotropic tongue tissue conductivity and relative permittivity properties, thus unfolding full forward and inverse EIM predictability capabilities. Significance. This new method of evaluating anisotropic tongue tissue will lead to a deeper understanding of the role of biology necessary for the development of new EIM tools and approaches for tongue health measurement and monitoring. (Source: Physiological Measurement)
Source: Physiological Measurement - May 30, 2023 Category: Physiology Authors: Xuesong Luo, Jian Shi, Arnau Mar ín Llobet, Seward B Rutkove and Benjamin Sanchez Source Type: research
Application of de-shape synchrosqueezing to estimate gait cadence from a single-sensor accelerometer placed in different body locations
Conclusion. We show that our proposed algorithm can extract the cadence with high accuracy, even when the sensor is placed on the wrist. (Source: Physiological Measurement)
Source: Physiological Measurement - May 30, 2023 Category: Physiology Authors: Hau-Tieng Wu and Jaroslaw Harezlak Source Type: research
Intra- and inter-rater reliability and agreement of stimulus electrodiagnostic tests in post-COVID-19 patients
Conclusion. The reliability of the SET obtained by independent raters was very high, except for the GL accommodation, which presented moderate ICC. Therefore, the SET is a reliable tool for evaluating NED in post-COVID-19 patients. (Source: Physiological Measurement)
Source: Physiological Measurement - May 24, 2023 Category: Physiology Authors: Isabella da Silva Almeida, Leandro Gomes de Jesus Ferreira, Álvaro de Almeida Ventura, Henrique Mansur, Nicolas Babault, Rita de Cássia Marqueti and João Luiz Quagliotti Durigan Source Type: research
A novel predictive analytics score reflecting accumulating disease burden —an investigation of the cumulative CoMET score
Objective. Predictive analytics tools variably take into account data from the electronic medical record, lab tests, nursing charted vital signs and continuous cardiorespiratory monitoring to deliver an instantaneous prediction of patient risk or instability. Few, if any, of these tools reflect the risk to a patient accumulated over the course of an entire hospital stay. Approach. We have expanded on our instantaneous CoMET predictive analytics score to generate the cumulative CoMET score (cCoMET), which sums all of the instantaneous CoMET scores throughout a hospital admission relative to a baseline expected risk unique t...
Source: Physiological Measurement - May 22, 2023 Category: Physiology Authors: Oliver Monfredi, Robert T Andris, Douglas E Lake and J Randall Moorman Source Type: research
A deep learning method for continuous noninvasive blood pressure monitoring using photoplethysmography
Objective. The aim of this study is to investigate continuous blood pressure waveform estimation from a plethysmography (PPG) signal, thus providing more human cardiovascular status information than traditional cuff-based methods. Approach. The proposed method utilizes the feature extraction ability of a convolution neural network to estimate blood pressure (BP) from PPG signals without the need for waveform analysis and signal feature extraction. Main results. The network achieved mean absolute errors and standard deviations of 2.55 ± 3.92 mmHg for systolic BP (SBP), 1.66 ± 2.76 mmHg for diastolic BP (DBP), and 2.52 ± ...
Source: Physiological Measurement - May 21, 2023 Category: Physiology Authors: Hao Liang, Wei He and Zheng Xu Source Type: research
Non-invasive detection of the content of white blood cells in the blood of humans based on dynamic spectrum
Objective. Changes in white blood cell content have been shown to be useful in determining whether the body is in a healthy state. We propose an improved data processing and modeling approach, which helps to accommodate blood component content detection and improve prediction accuracy. Approach. In this experiment, the finger-end transmission method was used for spectral measurement, and we collected a total of 440 sample data. In this paper, we first use the method of CEEMDAN combined with wavelet threshold to denoise the PPG signal, and then use the integral method to extract the spectral features, which makes up for the...
Source: Physiological Measurement - May 17, 2023 Category: Physiology Authors: Yanxi Huo, Guozhong Liu, Rixing Jing and Peng Zhao Source Type: research
A novel non-contact heart rate measurement method based on EEMD combined with FastICA
Objective. The imaging photoplethysmography (IPPG), which is applied to heart rate measurement, is susceptible to interference caused by illumination variations during photography. To improve the accuracy, robustness, and real-time performance of IPPG, a new method combined with modified ensemble empirical mode decomposition (EEMD) and fast independent component analysis (FastICA) was proposed. Approach. On the modified EEMD, to reduce the error caused by the residual white noise of the algorithm, it was characterized by recurrently updating zero-mean white noise for ensemble averaging based on the standard deviation of th...
Source: Physiological Measurement - May 10, 2023 Category: Physiology Authors: Yingli Shi, Jian Qiu, Li Peng, Peng Han, Kaiqing Luo and Dongmei Liu Source Type: research
On the distinct differences in autonomic regulation between pregnant and non-pregnant women - a heart rate variability analysis
Objective. Appropriate adaptation of the maternal autonomic nervous system to progressing gestation is essential to a healthy pregnancy. This is partly evidenced by the association between pregnancy complications and autonomic dysfunction. Therefore, assessing maternal heart rate variability (HRV) —a proxy measure for autonomic activity—may offer insights into maternal health, potentially enabling the early detection of complications. However, identifying abnormal maternal HRV requires a thorough understanding of normal maternal HRV. While HRV in women of childbearing age has been extensi vely investigated, less is kno...
Source: Physiological Measurement - May 9, 2023 Category: Physiology Authors: M Bester, R Joshi, M Mischi, JOEH van Laar and R Vullings Source Type: research
Improving generalization performance of electrocardiogram classification models
In this study, as part of the PhysioNet/Computing in Cardiology Challenge (PhysioNet Challenge) 2021, we present a model to classify cardiac abnormalities from the 12- and the reduced-lead ECGs. Approach. To improve the generalization performance of our earlier proposed model, we adopted a practical suite of techniques, i.e. constant-weighted cross-entropy loss, additional features, mixup augmentation, squeeze/excitation block, and OneCycle learning rate scheduler. We evaluated its generalization performance using the leave-one-dataset-out cross-validation setting. Furthermore, we demonstrate that the knowledge distillatio...
Source: Physiological Measurement - May 9, 2023 Category: Physiology Authors: Hyeongrok Han, Seongjae Park, Seonwoo Min, Eunji Kim, HyunGi Kim, Sangha Park, Jin-Kook Kim, Junsang Park, Junho An, Kwanglo Lee, Wonsun Jeong, Sangil Chon, Kwon-Woo Ha, Myungkyu Han, Hyun-Soo Choi and Sungroh Yoon Source Type: research
Autonomic control of heart and vessels in patients with very early stage of Parkinson disease
Objective. Non-motor symptoms including those reflecting autonomic cardiovascular dysregulation are often present in Parkinson disease. It is unclear whether it is possible to detect cardiovascular autonomic dysregulation in the very early stage of Parkinson disease potentially supporting the concept of the upstream propagation of nervous system damage through autonomic nerves. We hypothesized that cardiovascular dysregulation should precede the motor symptoms and at the time of their occurrence autonomic dysregulation should be clearly demonstrable. Therefore, the aim of this study was to assess the various aspects of aut...
Source: Physiological Measurement - May 8, 2023 Category: Physiology Authors: J Oleksakova, M Javorka, B Czippelova, N Mazgutova, M Grofik, L Babalova, P Skacik and E Kurca Source Type: research
Model-based spectral causality of cardiovascular variability interactions during head-down tilt
Objective. Cardiovascular control mechanisms are commonly studied during baroreceptor unloading induced by head-up tilt. Conversely, the effect of a baroreceptor loading induced by head-down tilt (HDT) is less studied especially when the stimulus is of moderate intensity and using model-based spectral causality markers. Thus, this study computes model-based causality markers in the frequency domain derived via causal squared coherence and Geweke spectral causality approach from heart period (HP) and systolic arterial pressure (SAP) variability series. Approach. We recorded HP and SAP variability series in 12 healthy men (a...
Source: Physiological Measurement - May 8, 2023 Category: Physiology Authors: Alberto Porta, Beatrice Cairo, Vlasta Bari, Francesca Gelpi, Beatrice De Maria and Riccardo Colombo Source Type: research
Automatic identifying OSAHS patients and simple snorers based on Gaussian mixture models
In this study, an effective OSAHS patient detection system based on snoring sounds is presented.Approach. The Gaussian mixture model (GMM) is proposed to explore the acoustic characteristics of snoring sounds throughout the whole night to classify simple snores and OSAHS patients respectively. A series of acoustic features of snoring sounds of are selected based on the Fisher ratio and learned by GMM. Leave-one-subject-out cross validation experiment based on 30 subjects is conducted to validation the proposed model. There are 6 simple snorers (4 male and 2 female) and 24 OSAHS patients (15 male and 9 female) investigated ...
Source: Physiological Measurement - May 2, 2023 Category: Physiology Authors: Xiaoran Sun, Li Ding, Yujun Song, Jianxin Peng, Lijuan Song and Xiaowen Zhang Source Type: research
Investigating spatial variations in dynamic cerebral autoregulation through a computational model of stenosis
Objective. Dynamic cerebral autoregulation (dCA) is a well-established mechanism that acts to maintain cerebral blood flow (CBF) reasonably constant in response to short-term fluctuations in blood pressure. It is known to be impaired in many clinical conditions, including stenosis, which is also a major risk factor for ischaemic stroke. However, it is not yet well understood whether impairment in dCA in one brain region is independent or not on dCA impairment in other brain regions, for example, whether there are spatial effects of stenosis on dCA. This is due to the complex blood flow environment and the lack of physiolog...
Source: Physiological Measurement - April 18, 2023 Category: Physiology Authors: Zheng Tong and Stephen J Payne Source Type: research
