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Physiological Measurement

Nikhilesh Pradhan, Sreeraman Rajan, Andy Adler
OBJECTIVE: 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. APPROACH: Ambulatory data were collected over a 24-hour period for 10 elderly, and 16 non-elderly participants...
May 17, 2019: Physiological Measurement
Brian Peter Lucas, Antonietta D'Addio, Clay Block, Harold Manning, Brian D Remillard, James Leiter
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 derived from capillary hemoglobin concentration from finger-clip spectrophotometry (RBVSpHb)...
May 15, 2019: Physiological Measurement
Emanuele Vaini, Vlasta Bari, Angela Fantinato, Valeria Pistuddi, Beatrice Cairo, Beatrice De Maria, Marco Ranucci, Alberto Porta
BACKGROUND: 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. OBJECTIVE: Our aim is to characterize cerebrovascular control in CABG patients through the assessment of the relationship between mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) and to check whether markers describing MCBFV-MAP dynamical interactions could identify subjects at risk to develop postoperative AKD...
May 15, 2019: Physiological Measurement
Christophe Louis Herry, Patrick Burns, André Desrochers, Gilles Fecteau, Lucien Daniel Durosier, Mingju Cao, Andrew J E Seely, Martin Gerbert Frasch
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 intra-surgical bilateral cervical vagotomy (n=15)...
May 15, 2019: Physiological Measurement
Sarah J Hamilton, Asko Hänninen, Andreas Hauptmann, Ville Kolehmainen
OBJECTIVE: 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. APPROACH: A D-bar method is paired with a trained Convolutional Neural Network (CNN) as a post-processing step. Training data is simulated for the network using no knowledge of the boundary shape by using an associated nonphysical Beltrami equation rather than simulating the traditional current and voltage data specific to a given domain...
May 15, 2019: Physiological Measurement
Hwa Pyung Kim, Sung Min Lee, Ja-Young Kwon, Yejin Park, Kang Cheol Kim, Jin Keun Seo
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 ultrasound images...
May 15, 2019: Physiological Measurement
Sabrina Demarie, Emanuele Chirico, Antonio Gianfelici, Giuseppe Vannozzi
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 Wingate Anaerobic Test were analysed...
May 9, 2019: Physiological Measurement
Andy Schumann, Stefanie Köhler, Lisa Brotte, Karl-Juergen Bär
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 training sessions per week including one session at the clinic's laboratory and four sessions at home using a mobile application running on their smartphone...
May 9, 2019: Physiological Measurement
Onno August Mennes, Jaap J van Netten, Jeff G van Baal, Wiendelt Steenbergen
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, and the ability of LSCI to discriminate between the degrees of ischemia...
May 9, 2019: Physiological Measurement
Joachim Behar, Julien Oster, Maarten De Vos, Gari D Clifford
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 review of in-clinic recordings, or detailed face-to-face interviews...
May 9, 2019: Physiological Measurement
Dirk Hoyer, Alexander Schmidt, Kathleen M Gustafson, Silvia M Lobmaier, Igor Victorovich Lakhno, Peter Van Leeuwen, Dirk Cysarz, Hubert Preissl, Uwe Schneider

 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 patterns (PATTERN) and common representatives for each category were extracted...
May 9, 2019: Physiological Measurement
Mirae Harford, Jacqueline Catherall, Stephen Gerry, J Duncan Young, Peter J Watkinson
Over the last 15 years, developments in camera technology have coincided with increased availability and affordability. This has led to an increasing interest in using these technologies in healthcare settings. Image-based monitoring methods allow multiple vital signs to be measured concurrently using a non-contact sensor. We have undertaken a systematic review of these monitoring methods. 
 Methods: A multiple database search was conducted using Medline, Embase, CINAHL, Cochrane Library, OpenGrey, IEEE Xplore Library, and ACM Digital Library to July 2018...
May 3, 2019: Physiological Measurement
Andre Dos Santos Rocha, Roberta Südy, Gergely H Fodor, Walid Habre, Ferenc Petak
Forced oscillation technique (FOT) is the method of choice for assessment of respiratory tissue mechanics. Laryngeal mask airway (LMA) is increasingly used to secure the airways in subjects under sedation or general anesthesia. While FOT is routinely performed using an endotracheal tube (ETT), the accuracy of information about airway and tissue mechanics obtained with FOT using a LMA has not been characterized. Therefore, we compared the mechanical parameters obtained with FOT using LMA and ETT in rabbits. 
 Approach: FOT was performed through a LMA at normal and reduced oscillatory amplitudes in anesthetized and mechanically ventilated rabbits (n=9) at positive end-expiratory pressures (PEEP) of 3 and 6 cmH2O...
May 3, 2019: Physiological Measurement
Geerthy Thambiraj, Uma Gandhi, Viji Devanand, Mangalanathan Umapathy
OBJECTIVE: Continuous cuffless blood pressure (BP) monitoring research emerges as blood pressure is one of the dynamic parameters which reflects the cardiac arrhythmias and rheological disorders. All the existing measurement techniques are cuff-based with drawbacks such as discontinuous in nature, patient comfort, etc. Therefore, the goal is to develop the algorithm to estimate BP accurately using Pulse Transit Time (PTT), Photoplethysmogram Intensity Ratio (PIR) and Womersley number (α) in a non-invasive way...
May 3, 2019: Physiological Measurement
Raksheeth Agarwal, Bill Chaudhry, Katrijn Jansen, John O'Sullivan, Mark Hudson, John Allen, Louise Coats
The Fontan operation greatly improves survival for single ventricle congenital heart disease patients but creates a physiology that leads to long-term multi-organ dysfunction. A non-invasive screening tool that can identify impending decline is sought. The objective of this pilot study was to assess the microcirculation in Fontan-palliated patients by measuring tissue oxygen saturation (StO2) in superficial and deeper tissues. 
 Approach: Three patient cohorts were studied: Fontan group (n=8) and two patient control groups, liver disease group (n=8) and tetralogy of Fallot group (n=9)...
May 3, 2019: Physiological Measurement
Junhua Wang, Yawei Wang, Ji Zhang, Shan Tian, Jianan Wei, Fang Pu, Yubo Fan
OBJECTIVE: 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. APPROACH: 10 male and 10 female subjects were enrolled in head-up tilt tests. Ultrasound screening was performed on the right IJV at five equidistant points between its junction with the subclavian vein and the location of the bifurcation of arteria carotis communis(ACC), with body at 0°, +10°, +20°, +30°, 40°, +50°, +60°, +70°, +80°, and +90°...
April 30, 2019: Physiological Measurement
Fansan Zhu, George A Kaysen, Shubho Sarkar, Fredric O Finkelstein, Mary Carter, Nathan W Levin, Nicholas A Hoenich
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/length), normalized resistivity (CNR=ρ/BMI) and calf extracellular volume (cECV) were calculated...
April 29, 2019: Physiological Measurement
Zhanqi Zhao, Hongli He, Jinying Luo, Andy Adler, Xiaoqing Zhang, Rongan Liu, Yunping Lan, Sen Lu, Xiaoxiu Luo, Yu Lei, Inez Frerichs, Xiaobo Huang, Knut Moeller
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 of the three positions, two-minute EIT data were recorded and analyzed...
April 29, 2019: Physiological Measurement
Hyeuknam Kwon, Cristian Rojas, Seward B Rutkove, Benjamin Sanchez
OBJECTIVE: 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. APPROACH: The approach is based on designing the input power spectrum multisine excitation by optimizing a scalar function of the information matrix using the Fricke-Morse model...
April 26, 2019: Physiological Measurement
Hannah Victoria Wilson, Ashley D Jones, Mark I Johnson, Peter Francis
CONTEXT: 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. AIM: To investigate the effects of inter-electrode distance (4cm, 5cm, 6cm and 7cm) on Dm and Tc of the biceps femoris, gastrocnemius medialis and biceps brachii, when the current amplitude is standardised...
April 26, 2019: Physiological Measurement
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