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Physiological Measurement

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https://www.readbyqxmd.com/read/28632138/monitoring-lung-contusion-in-a-porcine-polytrauma-model-using-eit-an-application-study
#1
Susana Aguiar Santos, Carlos Castelar Wembers, Klemens Horst, Roman Pfeifer, Tim-Philipp Simon, Hans-Christoph Pape, Frank Hildebrand, Michael Czaplik, Steffen Leonhardt, Daniel Teichmann
Lung contusion is the most common lung injury following blunt chest trauma which, in turn, is associated with high mortality rates (Gavelli et al., 2002). Lung contusion is characterized by hemorrhage and edema with consecutively reduced compliance. In this study, unilateral lung contusion and other traumata were induced in 12 pigs by using a bolt gun machine. To investigate the pathophysiological consequences of lung contusion, information on clinical parameters was collected and monitored regularly while animals were additionally monitored with electrical impedance tomography (EIT) before trauma, and at 4, 24, 48 and 72 h after polytrauma...
June 20, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28613208/ensemble-methods-with-outliers-for-phonocardiogram-classification
#2
Masun Nabhan Homsi, Philip Warrick
Heart sound classification and analysis play an important role in early diagnosis and prevention of cardiovascular disease. To this end, this paper introduces a novel method for automatic classification of normal and abnormal heart sound recordings. Signals are first preprocessed to extract a total of 131 features in time, frequency, wavelet and statistical domains from the entire signal and from the timings of the states. Outlier signals are then detected and separated from those with a standard range using interquartile range algorithm...
June 14, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28607221/vastus-lateralis-and-rectus-femoris-echo-intensity-fail-to-reflect-knee-extensor-specific-tension-in-middle-school-boys
#3
Jacob Mota, Matt S Stock, Brennan Thompson
The potential dissociation between muscle strength and size has led to interest in the ability to assess muscle quality across the lifespan. We examined the association between echo intensity and specific tension in middle-school boys. Twenty-five boys participated in this study. Sixteen (mean ± SD age = 12 ± 1 years) engaged in a 16-week after-school strength and conditioning program. Nine boys (12 ± 1 years) served as controls. The program involved two, 90 minute sessions per week of lower-body speed, power, and resistance training...
June 13, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28604356/ocular-surface-temperature-in-patients-with-evaporative-and-aqueous-deficient-dry-eyes-a-thermographic-approach
#4
Sara Matteoli, Eleonora Favuzza, Lucrezia Mazzantini, Pasquale Aragona, Stefania Cappelli, Andrea Corvi, Rita Mencucci
In recent decades infrared thermography (IR) has allowed accurate and quantitative measurements of the ocular surface temperature (OST), applying a non-invasive procedure. The objective of this work was to develop a procedure based on IR, which allows characterizing the cooling of the ocular surface of patients suffering from dry eye syndrome, and distinguishing among patients suffering from aqueous deficient dry eye (ADDE) and evaporative dry eyes (EDE). Approach: All patients examined (34F/4M, 23-84 years) were divided into two groups according to their Schirmer I result (≤7 mm for ADDE and >7 mm for EDE), and the OST was recorded for 7 s at 30Hz...
June 12, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28594641/detection-of-pathological-heart-sounds
#5
Mostafa Abdollahpur, Ali Ghaffari, Shadi Ghiasi, Mohammad Javad Mollakazemi
Heart sound analysis has been a major topic of research during the past few decades. However, necessity for a large reliable and database has been a major concern in these studies. Noting that the current heart sound classification methods do not work properly for noisy signals, the PhysioNet/CinC Challenge 2016 aims at developing the heart sound classification algorithms by providing a global open database for challengers. This paper addresses the problem of heart sound classification methods within noisy real-world phonocardiogram (PCG) recordings by implementing an innovative approach...
June 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28594638/recognition-of-normal-abnormal-phonocardiographic-signals-using-deep-convolutional-neural-networks-and-mel-frequency-spectral-coefficients
#6
Vykintas Maknickas, Algirdas Maknickas
Intensive care unit patients are heavily monitored, and several clinically relevant parameters are routinely extracted from high resolution signals. The goal of the 2016 PhysioNet/CinC Challenge was to encourage the creation of an intelligent system that fused information from different phonocardiographic signals to create a robust set of normal/abnormal signal detections. Methods: Deep convolutional neural networks and mel-frequency spectral coefficients were used for recognition of normal-abnormal phonocardiographic signals of the human heart...
June 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28573981/at-what-data-length-do-cerebral-autoregulation-measures-stabilise
#7
Adam Mahdi, Dragana Nikolic, Antony Birch, Stephen Payne
Cerebral autoregulation is commonly assessed through mathematical models that use non-invasive measurements of arterial blood pressure and cerebral blood flow velocity. There is no agreement in the literature as to what is the minimum length of data needed for the cerebral autoregulation coefficients to stabilise. We introduce a simple empirical tool for studying the minimum length of time series needed to parameterise three popular cerebral autoregulation coefficients ARI, Mx and Phase (in the low frequency range [0...
June 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28569241/atrial-fibrillation-detection-on-compressed-sensed-ecg
#8
Giulia Da Poian, Chengyu Liu, Riccardo Bernardini, Roberto Rinaldo, Gari Clifford
OBJECTIVE: Compressive Sensing (CS) approaches to electrocardiogram (ECG) analysis provide efficient methods for real time encoding of cardiac activity. In doing so, it is important to assess the downstream effect of the compression on any signal processing and classification algorithms. CS is particularly suitable for low power wearable devices, thanks to its low-complex digital or hardware implementation that directly acquires a compressed version of the signal through random projections...
June 1, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28562369/combining-sparse-coding-and-time-domain-features-for-heart-sound-classification
#9
Bradley M Whitaker, Pradyumna Byappanahalli Suresha, Chengyu Liu, Gari Clifford, David Anderson
This paper builds upon work submitted as part of the 2016 PhysioNet/CinC Challenge, which used sparse coding as a feature extraction tool on audio PCG data for heart sound classification. In sparse coding, preprocessed data is decomposed into a dictionary matrix and a sparse coefficient matrix. The dictionary matrix represents statistically important features of the audio segments. The sparse coefficient matrix is a mapping that represents which features are used by each segment. Working in the sparse domain, we train support vector machines (SVMs) for each audio segment (S1, systole, S2, diastole) and a full cardiac cycle...
May 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28562368/heart-sounds-analysis-using-probability-assessment
#10
Filip Plesinger, Ivo Viscor, Josef Halamek, Juraj Jurco, Pavel Jurak
This paper describes a method for automated discrimination of heart sounds recordings according to the Physionet Challenge 2016. The goal was to decide if the recording refers to normal or abnormal heart sounds or if it is not possible to decide (i.e. "unsure" recordings). Approach: Heart sounds S1 and S2 are detected using amplitude envelopes in the band 15-90 Hz. The averaged shape of the S1/S2 pair is computed from amplitude envelopes in five different bands (15-90 Hz; 55-150 Hz; 100-250 Hz; 200-450 Hz; 400-800 Hz)...
May 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28530209/reproducible-3d-printed-head-tanks-for-electrical-impedance-tomography-with-realistic-shape-and-conductivity-distribution
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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/28489019/heart-sound-classification-from-unsegmented-phonocardiograms
#17
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
#18
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
#19
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
#20
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
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