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Physiological Measurement

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https://www.readbyqxmd.com/read/28530209/reproducible-3d-printed-head-tanks-for-electrical-impedance-tomography-with-realistic-shape-and-conductivity-distribution
#1
James Avery, Kirill Aristovich, Barney Low, David Holder
OBJECTIVE: Electrical impedance tomography (EIT) has many promising applications in brain injury monitoring. To evaluate both instrumentation and reconstruction algorithms, experiments are first performed in head tanks. Existing methods, whilst accurate, produce a discontinuous conductivity, and are often made by hand, making it hard for other researchers to replicate. APPROACH: We have developed a method for constructing head tanks directly in a 3D printer. Conductivity was controlled through perforations in the skull surface, which allow for saline to pass through...
May 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28530208/eit-imaging-of-admittivities-with-a-d-bar-method-and-spatial-prior-experimental-results-for-absolute-and-difference-imaging
#2
S J Hamilton
Electrical impedance tomography (EIT) is an emerging imaging modality that uses harmless electrical measurements taken on electrodes at a body's surface to recover information about the internal electrical conductivity and or permittivity. The image reconstruction task of EIT is a highly nonlinear inverse problem that is sensitive to noise and modeling errors making the image reconstruction task challenging. D-bar methods solve the nonlinear problem directly, bypassing the need for detailed and time-intensive forward models, to provide absolute (static) as well as time-difference EIT images...
May 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28530206/16th-international-conference-on-electrical-bio-impedance-and-17th-international-conference-on-biomedical-applications-of-electrical-impedance-tomography-eit
#3
Richard Bayford, Stig Ollmar
No abstract text is available yet for this article.
May 22, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28497774/evaluation-of-respiratory-and-postural-induced-changes-on-the-ballistocardiogram-signal-by-time-warping-averaging
#4
Alba Martin-Yebra, Federica Landreani, Claudia Casellato, Esteban Enrique Pavan, Pierre-François Migeotte, Carlo Frigo, Juan Martinez Cortes, Enrico Caiani
OBJECTIVE: The aim of this work was to evaluate the potential changes in the ballistocardiogram (BCG) signal induced by different respiratory patterns and posture, by using the dynamic time warping (DTW) technique. APPROACH: BCG signals were recorded in a group of 20 healthy volunteers, simultaneously to the ECG. Two recordings, one in supine (SUP) and one in standing (ST) position, including spontaneous breathing, two 1-minute apneas (at full and empty-lungs, respectively) and 30s of Valsalva, were analyzed...
May 12, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28493849/effects-of-pressure-variation-and-atrial-fibrillation-on-cardiomems-%C3%A2-hf-measured-pulmonary-artery-diastolic-pressure-comparison-of-device-averaged-and-visually-inspected-waveforms
#5
Aaron M Wolfson, Omid Yousefian, Lindsay Short, Daniel O'Brien, Guy Talmor, Jessica Qiu, Andrew Yoon, Michael Fong, Leslie Saxon, Rahul Doshi, Luanda Grazette, David M Shavelle
OBJECTIVE: Heart failure (HF) management guided by implantable hemodynamic monitoring reduces hospitalization rates. Hemodynamic data from the CardioMEMS(™) HF system includes device-averaged pulmonary artery pressures (PAP) and heart rate. Agreement of device-averaged values compared to the standard method of visual inspection of pressure waveforms at end-expiration is unknown. We evaluated the agreement between device-averaged and visually inspected end-expiratory PAP. APPROACH: Twenty-one patients implanted with the CardioMEMS(™) HF system were evaluated...
May 11, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28489610/invasive-and-noninvasive-means-of-measuring-intracranial-pressure-a-review
#6
Xuan Zhang, Joshua Medow, Bermans Iskandar, Fa Wang, Mehdi Shokoueinejad, Joyce Koueik, John Webster
Measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Cerebrospinal fluid (CSF) is produced by the choroid plexus in the brain ventricles (a set of communicating chambers), after which it circulates through the different ventricles and exits into the subarachnoid space (SAS) around the brain, where it is reabsorbed into the venous system. If the fluid does not drain out of the brain or get reabsorbed, the ICP increases, which may lead to brain damage or death...
May 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28489609/heart-rate-based-window-segmentation-improves-accuracy-of-classifying-posttraumatic-stress-disorder-using-heart-rate-variability-measures
#7
Erik Reinertsen, Shamim Nemati, Adriana N Vest, Viola Vaccarino, Rachel Lampert, Amit J Shah, Gari D Clifford
OBJECTIVE: Heart rate variability (HRV) characterizes changes in autonomic nervous system function and varies with posttraumatic stress disorder (PTSD). In this study we developed a classifier based on heart rate (HR) and HRV measures, and improved classifier performance using a novel HR-based window segmentation. APPROACH: Single-channel ECG data were collected from 23 subjects with current PTSD, and 25 control subjects with no history of PTSD over 24 h. RR intervals were derived from these data, cleaned, and used to calculate HR and HRV metrics...
May 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28489019/heart-sound-classification-from-unsegmented-phonocardiograms
#8
Philip Langley, Alan Murray
Objective Most algorithms for automated analysis of phonocardiograms (PCG) require segmentation of the signal into the characteristic heart sounds. The aim was to assess the feasibility for accurate classification of heart sounds on short, unsegmented recordings. Approach PCG segments of 5 second duration from the PhysioNet/Computing in Cardiology Challenge database were analysed. Initially the 5 second segment at the start of each recording (seg 1) was analysed. Segments were zero-mean but otherwise had no pre-processing or segmentation...
May 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28489018/estimating-sleep-parameters-using-nasal-pressure-signals-applicable-to-continuous-positive-airway-pressure-cpap-devices
#9
Jong-Uk Park, Urtnasan Erdenebayar, Eun-Yeon Joo, Kyoung-Joung Lee
This paper proposes a method for classifying sleep-wakefulness and estimating sleep parameters using nasal pressure signals applicable to a continuous positive airway pressure (CPAP) device. In order to classify the sleep-wakefulness states of patients with sleep-disordered breathing (SDB), apnea-hypopnea and snoring events are first detected. Detected epochs as SDB are classified as sleep, and time domain and frequency domain-based features are extracted from epochs that are detected as normal breathing. Subsequently, sleep-wakefulness is classified using a support vector machine (SVM) classifier in the normal breathing epoch...
May 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28481751/robust-heart-rate-from-fitness-videos
#10
Wenjin Wang, Albertus C den Brinker, Sander Stuijk, Gerard de Haan
Remote photoplethysmography (rPPG) enables contactless heart-rate monitoring using a regular video camera. OBJECTIVE: This paper aims to improve the rPPG technology targeting continuous heart-rate measurement during fitness exercises. The fundamental limitation of the existing (multi-wavelength) rPPG methods is that they can suppress at most n  -  1 independent distortions by linearly combining n wavelength color channels. Their performance are highly restricted when more than n  -  1 independent distortions appear in a measurement, as typically occurs in fitness applications with vigorous body motions...
May 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28481750/lab-based-validation-of-different-data-processing-methods-for-wrist-worn-actigraph-accelerometers-in-young-adults
#11
Laura D Ellingson, Paul R Hibbing, Youngwon Kim, Laura A Frey-Law, Pedro F Saint-Maurice, Gregory J Welk
The wrist is increasingly being used as the preferred site for objectively assessing physical activity but the relative accuracy of processing methods for wrist data has not been determined. OBJECTIVE: This study evaluates the validity of four processing methods for wrist-worn ActiGraph (AG) data against energy expenditure (EE) measured using a portable metabolic analyzer (OM; Oxycon mobile) and the Compendium of physical activity. APPROACH: Fifty-one adults (ages 18-40) completed 15 activities ranging from sedentary to vigorous in a laboratory setting while wearing an AG and the OM...
May 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28480874/emerging-applications-of-nanotechnology-for-diagnosis-and-therapy-of-disease-a-review
#12
Richard H Bayford, Tom Rademacher, Ivan Roitt, Scarlet Wang
Nanotechnology is of increasing interest in the fields of medicine and physiology over recent years. Its application could considerably improve disease detection and therapy, and although the potential is considerable, there are still many challenges, which need to be addressed before it is accepted in routine clinical use. This review focuses on emerging applications that nanotechnology could enhance or provide new approaches in diagnoses and therapy. The main focus of recent research centres on targeted therapies and enhancing imaging; however, the introduction of nanomaterial into the human body must be controlled, as there are many issues with possible toxicity and long-term effects...
May 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28471753/improving-the-quality-and-accuracy-of-non-invasive-blood-pressure-measurement-by-visual-inspection-and-automated-signal-processing-of-the-korotkoff-sounds
#13
Branko G Celler, Phu Le, Jim Basilakis, Eliathamby Ambikairajah
OBJECTIVE: In this study we investigate inter-operator differences in determining systolic and diastolic pressure from auscultatory sound recordings of Korotkoff sounds. We introduce a new method to record and convert Korotkoff sounds to a high fidelity sound file which can be replayed under optimal conditions by multiple operators, for the independent determination of systolic and diastolic pressure points. APPROACH: We have developed a digitised data base of 643 NIBP records from 216 subjects...
May 4, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28467322/a-modification-of-the-bohr-method-to-determine-airways-deadspace-for-non-uniform-inspired-gas-tensions
#14
Phi Anh Phan, Clive Hahn, Andrew Farmery
The Bohr method is a technique to determine airways deadspace using a tracer gas such as carbon dioxide or nitrogen. It is based on the assumption that the inspired concentration of the tracer gas is constant throughout inspiration. However, in some lung function measurement techniques where inspired concentration of the tracer gas may be required to vary, or where rapid injection of the tracer gas is made in real time, uniform inspired concentration is difficult or impossible to achieve, which leads to inaccurate estimation of deadspace using the Bohr equation...
May 3, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28462905/the-dielectric-spectroscopy-of-human-red-blood-cells-the-differentiation-of-old-from-fresh-cells
#15
Marcelo Martin David, Evgeniya Levy, Yuri Feldman, Paul Ben Ishai, Orly Zelig, Saul Yedgar, Gregory Barshtein
The dielectric response of Red Blood Cells (RBC) suspensions, exposed to blood-bank cold storage, was studied using Time-Domain Dielectric Spectroscopy in the frequency range of 500 kHz up to 1 GHz. The measured dielectric processes are characterized by their dielectric strength (Δε) and relaxation time (τ). Changes in the dielectric properties of the RBC suspensions due to storage-related lesions were evaluated. For a quantitative characterization of RBC lesions, we measured the deformability of fresh and stored RBC as expressed by their elongation ratio (ER), which was achieved under a shear stress of 3...
May 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28443830/paco-sub-2-sub-measurement-in-cerebral-haemodynamics-face-mask-or-nasal-cannulae
#16
Jatinder Singh Minhas, Thompson Robinson, Ronney Panerai
Objective PaCO2 affects cerebral blood flow (CBF) and its regulatory mechanisms, but the effects of CO2 measurement technique on cerebrovascular parameters are unknown. In order to determine if the two most commonly used approaches, face mask (FM) or nasal cannulae (NC), are interchangeable or not, we tested the hypothesis that the use of FM versus NC does not lead to significant differences in CO2-related systemic and cerebrovascular parameters. Approach Recordings of CBF velocity (CBFV), blood pressure (BP), heart rate, and end-tidal CO2 (EtCO2) were performed in 42 subjects during normocapnia (FM or NC) and 5% CO2 inhalation (FM) or hyperventilation (NC)...
April 26, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28430667/enhanced-thermal-imaging-of-wound-tissue-for-better-clinical-decision-making
#17
Ellen Keenan, Georgina Gethin, Louisa Flynn, David Watterson, Gerard M O'Connor
Infrared cameras are increasingly applied in clinical applications as they allow fast, inexpensive and non-contact temperature measurements. As abnormal heat distribution can indicate illness, infrared cameras have been applied in the prediction, diagnosis and monitoring of medical conditions. Current practices, however, often overlook the importance of emissivity when taking thermal measurements. The consensus is that human skin has an emissivity of 0.98 but this value varies between individuals, areas examined, and if the skin is damaged...
April 21, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28430109/acquisition-of-electrocardiogram-signals-during-magnetic-resonance-imaging
#18
Julien Oster, Gari Clifford
The recording of the electrocardiogram (ECG) during Magnetic Resonance Imaging (MRI) acquisition is of great interest and importance. Firstly, MRI acquisition is a relatively slow process, which therefore complicates the imaging of moving organs. Cardiac MRI requires the development of strategies for acquiring high quality images, which is mainly achieved by synchronising the image acquisition with a specific time during the cardiac cycle. The ECG is used to monitor the heart's activity, and the detection of the largest and steepest peak in the cardiac cycle (the QRS complex) triggers the acquisition of slices of the k-space...
April 21, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28430108/a-network-physiology-approach-to-the-assessment-of-the-link-between-sinoatrial-and-ventricular-cardiac-controls
#19
Alberto Porta, Vlasta Bari, Beatrice De Maria, Mathias Baumert
A network physiology approach to evaluate the strength of the directed interactions among cardiac controls at sinoatrial and ventricular levels and respiration (R) is proposed. The network is composed of three nodes (i.e. sinoatrial and ventricular cardiac controls and R) and their activity is exemplified by the variability of heart period (HP), the variability of the duration of the electrical activity of the heart approximated as the temporal distance between Q-wave onset and T-wave end or apex (i.e. QTe or QTa) and thoracic movements respectively...
April 21, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28378711/input-respiratory-impedance-in-mice-comparison-between-the-flow-based-and-the-wavetube-method-to-perform-the-forced-oscillation-technique
#20
V Mori, M A Oliveira, M H M Vargas, A A da Cunha, R G de Souza, P M Pitrez, H T Moriya
Objective and approach: In this study, we estimated the constant phase model (CPM) parameters from the respiratory impedance of male BALB/c mice by performing the forced oscillation technique (FOT) in a control group (n  =  8) and in a murine model of asthma (OVA) (n  =  10). Then, we compared the results obtained by two different methods, using a commercial equipment (flexiVent-flexiWare 7.X; SCIREQ, Montreal, Canada) (FXV) and a wavetube method equipment (Sly et al 2003 J. Appl. Physiol. 94 1460-6) (WVT)...
April 5, 2017: Physiological Measurement
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