PubMed Journal Database | Physiological measurement RSS

06:52 EDT 24th May 2019 | BioPortfolio

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Showing PubMed Articles 1–25 of 261 from Physiological measurement

Measuring muscle size and symmetry in healthy adult males using a time-efficient analysis of magnetic resonance images.

Muscle volume (MV) analysis from magnetic resonance imaging (MRI) is time-intensive, and limited measurement reliability data are available. This study investigated a method to reduce lower limb MV analysis time demands, established reliability of these measurements, and applied the findings to quantify muscle size and symmetry in healthy adult males. 
 Approach: Bilateral MRI images were acquired from 15 healthy males (age: 26.5 ±4.6 years, height: 1.81 ±0.09 m, body mass: 80.4 ±12.4 k...

Evaluation of the signal quality of wrist-based photoplethysmography.

Wearable devices with embedded photoplethysmography (PPG) sensors enable continuous monitoring of cardiovascular activity, allowing for the detection cardiovascular problems, such as arrhythmias. However, the quality of wrist-based PPG is highly variable, and is subject to artifacts from motion and other interferences. The goal of this paper is to evaluate the signal quality obtained from wrist-based PPG when used in an ambulatory setting.

Automatic evaluation of fetal head biometry from ultrasound images using machine learning.

Ultrasound-based fetal biometric measurements, such as head circumference (HC) and biparietal diameter (BPD), are frequently used to evaluate gestational age and diagnose fetal central nervous system (CNS) pathology. Because manual measurements are operator-dependent and time-consuming, much research is being actively conducted on automated methods. However, existing automated methods are still not satisfactory in terms of accuracy and reliability, owing to diculties dealing with various artifacts in ultras...

Beltrami-net: domain independent deep D-bar learning for absolute imaging with electrical impedance tomography (a-EIT).

To develop, and demonstrate the feasibility of, a novel image reconstruction method for absolute Electrical Impedance Tomography (a-EIT) that pairs deep learning techniques with real-time robust D-bar methods and examine the influence of prior information on the reconstruction.

Vagal contributions to fetal heart rate variability: an omics approach.

Fetal heart rate variability (fHRV) is an important indicator of health and disease, yet its physiological origins, neural contributions, in particular, are not well understood. We aimed to develop novel experimental and data analytical approaches to identify fHRV measures reflecting the vagus nerve contributions to fHRV. In near-term ovine fetuses, a comprehensive set of 46 fHRV measures was computed from fetal pre-cordial electrocardiogram recorded during surgery and 72 hours later without (n=24) and with...

Causality analysis reveals the link between cerebrovascular control and acute kidney dysfunction after coronary artery bypass grafting.

Patients undergoing coronary artery bypass graft (CABG) surgery might experience postoperative complications and some of them, such as acute kidney dysfunction (AKD), are the likely consequence of hypoperfusion. We hypothesized that an impaired cerebrovascular control is a hallmark of a vascular damage that might favor AKD after CABG.

Limited agreement between two noninvasive measurements of blood volume during fluid removal: ultrasound of inferior vena cava and finger-clip spectrophotometry of hemoglobin concentration.

Plots of blood volume measurements over time (profiles) may identify euvolemia during fluid removal for acute heart failure. We assessed agreement between two noninvasive measurements of blood volume profiles during mechanical fluid removal, which exemplifies the interstitial fluid shifts that occur during diuretic-induced fluid removal.
 Approach: During hemodialysis we compared change in maximum diameter of the inferior vena cava by ultrasound (IVCUS) to change in relative blood volume d...

Heart rate variability categories of fluctuation amplitude and complexity - diagnostic markers of fetal development and its disturbances.

 In fetal diagnosis the myriad and diversity of heart rate variability (HRV) indices prevents a comparable routine evaluation of disturbances in fetal development and well-being. The work aims at the extraction of a small set of HRV key indices that could help to establish a universal, overarching tool to screen for any disturbance. 
 HRV indices were organized in categories of short-term (s) and long-term (l) amplitude fluctuations (AMP), complexity (COMP), and...

Wearables and mHealth in mental health and neurological disorders.

According to the World Health Organization, neuropsychiatric conditions account for up to one third of years lived with disability among adults worldwide (Chisholm 2015). In addition, it is estimated that almost 50% of adults will develop at least one mental illness over their lifetime (Center for Disease Control and Prevention 2011). Mental health diagnosis, and (to a large extent) neurological disorders, still rely on traditional subjective clinical evaluation performed using standardized scales, manual r...

Assessment of microcirculation in the diabetic foot with laser speckle contrast imaging.

A major challenge for treating diabetic foot ulcers is estimating the severity of ischemia, as currently used non-invasive diagnostic techniques provide relatively poor prognostic values. Laser Speckle Contrast Imaging (LSCI) is a promising non-invasive technique to assess microcirculation. Our aim was to investigate the stability and reproducibility of LSCI for the assessment of microcirculation in the diabetic foot, the relation of LSCI results to currently used non-invasive blood pressure measurements, a...

Effect of an 8-week smartphone-guided HRV-biofeedback intervention on autonomic function and impulsivity in healthy controls.

A large body of scientific studies suggest a close relationship between increased vagal function and better cognitive performance. In the current study, we investigated the association between autonomic function and behavioral impulsivity. We hypothesized that heart rate variability (HRV) biofeedback training increases HRV and enhances inhibitory control. 
 A total of 28 healthy participants were recruited. After drop-out, 14 participants completed an 8-week HRV biofeedback training with five traini...

Anaerobic capacity assessment in elite swimmers through inertial sensors.

The present study aimed to assess if changes in speed and stroke parameters, as measured by an inertial sensor during a maximal effort swimming test, could provide an effective detection of anaerobic capacity in elite swimmers.
 Approach. Fourteen elite swimmers performed a 75m maximal swimming test. Changes in speed and stroke parameters, estimated by a body-worn inertial sensor, were analysed to provide insight into stroke mechanics during swimming. Their relationships with the output of the Winga...

In vivo measurements of collapse behavior of human internal jugular vein during head-up tilt tests.

Human internal jugular veins (IJVs) would collapse during posture change from supine to erect, which might influence intracranial hemodynamic. This study aimed to quantitatively describe the gradual collapse behavior of human IJVs during head-up tilt tests from supine to erect.

Detection of pulmonary oedema by electrical impedance tomography - validation of previously proposed approaches in a clinical setting.

The aim of the present study was to evaluate two previously proposed approaches based on electrical impedance tomography (EIT) to assess pulmonary oedema at the bedside. 
 Approach: Fourteen patients with acute respiratory distress syndrome were included and examined prospectively. Patients were rotated laterally along their longitudinal axis from supine to 45-degree left and right tilt to induce a gravity-dependent redistribution of pulmonary oedema. After a 20-minute equilibration periods at each ...

Evaluation of one year frequent dialysis on fluid load and body composition using calf bioimpedance technique.

Background The primary aim of this study was to evaluate the effect of increased frequency of dialysis (FHD) on change in fluid status and body composition using segmental bioimpedance.
 Methods 12 stable HD patients were switched from 3 times/week to 6 times/week HD (FHD). Systolic blood pressure (SBP), body mass and body mass index (BMI) were measured pre- and post-HD. Calf resistance (R5) at 5 kHz was measured using a multifrequency bioimpedance device (Hydra 4200). Calf resistivity (ρ=R5*area/l...

The effect of inter-electrode distance on radial muscle displacement and contraction time of the biceps femoris, gastrocnemius medialis and biceps brachii, using Tensiomyography in healthy participants.

The systematic effect of inter-electrode distance on electrically elicited radial muscle displacement (Dm) and contraction time (Tc) of the biceps femoris, gastrocnemius medialis and biceps brachii using Tensiomyography (TMG) is currently unavailable.

Three-harmonic optimal multisine input power spectrum for bioimpedance identification.

The attention towards optimal signals for measuring electrical bioimpedance (EBI) has increased recently due to the many advantages they offer such as, for example, reduced measuring time. Here, the design of a three-harmonic optimized multisine input power spectrum for measuring bioimpedance is considered.

Effects of prefabricated and custom-made foot orthoses on skin temperature of the foot soles after running.

Foot orthoses are increasingly used by runners despite the controversy about whether its use can reduce the risk of overuse injuries. Some authors have found modifications in plantar pressures with the use of foot orthoses, which could produce changes in surface skin temperature of the foot soles. The aim of the study was to analyse the effects of custom-made and prefabricated foot orthoses on skin temperature of different regions of both foot soles after running. Twenty-four participants carried out a maxi...

Objective assessment of blinking and facial expressions in Parkinson's disease using vertical electrooculogram and facial surface electromyography.

Hypomimia is a common and early symptom of Parkinson's disease (PD), which reduces the ability of PD patients in manifesting emotions. Currently, it is visually evaluated by the neurologist during neurological examinations for PD diagnosis as described in task 3.2 of the Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Since such evaluation is semi-quantitative and affected by inter-variability, this paper aims to measure physiological parameters related to eye blink and fac...

Parameterizing and validating existing algorithms for identifying out-of-bed time using hip-worn accelerometer data from older women.

To parameterize and validate two existing algorithms for identifying out-of-bed time using 24-hour hip-worn accelerometer data from older women. 
 Approach: Overall, 628 women (80±6 years old) wore ActiGraph GT3X+ accelerometers 24 hours/day for up to 7 days and concurrently completed sleep-logs. Trained staff used a validated visual analysis protocol to measure in-bed periods on accelerometer tracings (criterion). The Tracy and McVeigh algorithms were adapted for optimal use in older adu...

Cutaneous perfusion of the human lactating breast: a pilot study with laser Doppler perfusion monitoring.

<i>Objective</i>: Knowledge on the hemodynamics of the human lactating breast contributes to our understanding of lactation physiology, as well as the development and management of breastfeeding problems. The objective of this pilot study was to investigate whether laser Doppler perfusion monitoring (LDPM) can be employed to measure physiological changes in mammary cutaneous perfusion during milk extraction. <i>Approach</i>: We evaluated mammary cutaneous perfusion with LDPM in...

Chest electrical impedance tomography measures in neonatology and paediatrics - a survey on clinical usefulness.

Chest electrical impedance tomography (EIT) is currently applied in neonatal and paediatric patients mainly within clinical studies. The findings of these studies imply that lung monitoring using EIT provides valuable information on regional lung ventilation and aeration at the bedside that might improve the therapy and care of this fragile patient population. In view of this postulated future use of EIT in neonatology and paediatrics we have conducted an international survey to assess the perceived usefuln...

Heart rate variability monitoring for emotion and disorders of emotion.

Emotion is composed of cognitive processing, physiological response and behavioral reaction. Heart rate variability (HRV) refers to the fluctuations between consecutive heartbeat cycles, which is considered as non-invasive method for evaluating cardiac autonomic function. HRV analysis plays an important role in emotional study and detection. In this paper, the physiological foundation of HRV is briefly described, and then the relevant literatures about the HRV-based emotion studies for the performances of H...

Effects of different classroom temperatures on cardiac autonomic control and cognitive performances in undergraduate students.

Indoor microclimate may affect students' wellbeing, cardiac autonomic control and cognitive performance with potential impact on learning capabilities. Aim. To assess the effects of classroom temperature variations on the autonomic profile and student's cognitive capabilities. Methods. Twenty students attending Humanitas University School, (14M, age 21±3yrs) underwent a single lead ECG continuous recording by a portable device during a 2-hour lecture when classroom temperature was set "neutral" (...

Ventricular ectopic beat detection using a wavelet transform and a convolutional neural network.

\emph{Objective:} Ventricular contractions in healthy individuals normally follow the contractions of atria to facilitate more efficient pump action and cardiac output. With a ventricular ectopic beat (VEB), volume within the ventricles are pumped to the body's vessels before receiving blood from atria, thus causing inefficient blood circulation. VEBs tend to cause perturbations in the instantaneous heart rate time series, making the analysis of heart rate variability inappropriate around such events, or re...

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