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https://www.readbyqxmd.com/read/29908395/a-novel-compliance-pressure-loop-approach-to-quantify-arterial-compliance-in-systole-and-in-diastole
#1
Mehmet Kaya, Vignesh Balasubramanian, Amit Patel, Yueya Ge, John K-J Li
Arterial compliance has been recognized as a critical parameter in governing pulsatile flow dynamics. It has traditionally been assumed constant throughout the cardiac cycle and its computation has been based either on the classic Windkessel model (C) in diastole or the stroke volume over pulse pressure (Cv ) method in systole. Other methods using area (Cam ) or two-area (Ctam ) and exponential (C(P)exp1 ) methods were used for the cardiac cycle. We proposed a novel compliance-pressure loop (CPP loop) approach for the quantification of arterial compliance and compared it to existing linear and nonlinear methods...
June 5, 2018: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/29896107/construction-and-validation-of-subject-specific-biventricular-finite-element-models-of-healthy-and-failing-swine-hearts-from-high-resolution-dt-mri
#2
Kevin L Sack, Eric Aliotta, Daniel B Ennis, Jenny S Choy, Ghassan S Kassab, Julius M Guccione, Thomas Franz
Predictive computational modeling has revolutionized classical engineering disciplines and is in the process of transforming cardiovascular research. This is particularly relevant for investigating emergent therapies for heart failure, which remains a leading cause of death globally. The creation of subject-specific biventricular computational cardiac models has been a long-term endeavor within the biomedical engineering community. Using high resolution (0.3 × 0.3 × 0.8 mm) ex vivo data, we constructed a precise fully subject-specific biventricular finite-element model of healthy and failing swine hearts...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29867563/investigating-the-role-of-interventricular-interdependence-in-development-of-right-heart-dysfunction-during-lvad-support-a-patient-specific-methods-based-approach
#3
Kevin L Sack, Yaghoub Dabiri, Thomas Franz, Scott D Solomon, Daniel Burkhoff, Julius M Guccione
Predictive computation models offer the potential to uncover the mechanisms of treatments whose actions cannot be easily determined by experimental or imaging techniques. This is particularly relevant for investigating left ventricular mechanical assistance, a therapy for end-stage heart failure, which is increasingly used as more than just a bridge-to-transplant therapy. The high incidence of right ventricular failure following left ventricular assistance reflects an undesired consequence of treatment, which has been hypothesized to be related to the mechanical interdependence between the two ventricles...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29866281/pulmonary-function-tests-for-the-generalist-a-brief-review
#4
REVIEW
Timothy M Dempsey, Paul D Scanlon
One of the frequent reasons patients see their primary care physicians is for the symptom of dyspnea. Among the objective tests to quantify this symptom is the pulmonary function test, which includes several different studies: spirometry with flow-volume loop, lung volumes, and diffusing capacity of lung for carbon monoxide. The results may indicate both respiratory and nonrespiratory disorders, including helping in the diagnosis of cardiac or neuromuscular diseases. This review, intended for the generalist, describes common findings of pulmonary function tests and provides a road map for interpretation...
June 2018: Mayo Clinic Proceedings
https://www.readbyqxmd.com/read/29797692/upper-airway-obstruction-assessment-peak-inspiratory-flow-and-clinical-copd-questionnaire
#5
Jose Sanchez-Guerrero, Joanne Guerlain, Sabine Samaha, Alice Burgess, Jean Lacau St Guily, Sophie Périé
OBJECTIVES: Spirometric evaluation of upper airway obstruction (UAO) is not commonly performed by Otolaryngologists. In addition, functional evaluation of UAO by flow volume loops (FVL) is not available in all clinical settings. More recently, peak inspiratory flow (PIF) has proven to be a useful tool to monitor UAO at the patient's bedside. The aim of this work is to assess the role of PIF measured with a simple flow-meter (In-Check method) as a standardized, simple, non-invasive tool in quantifying chronic and subacute UAO in a routine clinical practice...
May 24, 2018: Clinical Otolaryngology
https://www.readbyqxmd.com/read/29754713/endoscopic-partial-arytenoidectomy-for-bilateral-vocal-fold-paralysis-medially-based-mucosal-flap-technique
#6
Taner Yılmaz
PURPOSE: Endoscopic partial arytenoidectomy (EPA) is one of the static operations for treatment of bilateral vocal fold paralysis (BVFP). Improvement in airway may cause voice loss and aspiration. The author reports his experience on EPA using medially based mucosal flap to enlarge posterior glottis without removing any part of membranous vocal fold. MATERIALS AND METHODS: Sixty-four consecutive patients with BVFP underwent EPA. Pre- and postoperative evaluations included Voice Handicap Index-30, aerodynamic and acoustic analysis, flow volume loops, perceptual evaluation of pre- and postoperative voice using grade, roughness, breathiness, asthenia, strain (GRBAS) scale, speech intensity, breathing ability evaluation, and functional outcome swallowing scale...
May 10, 2018: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/29715362/characterizing-the-heartmate-ii-left-ventricular-assist-device-outflow-using-particle-image-velocimetry
#7
Grant W Rowlands, Bryan C Good, Steven Deutsch, Keefe B Manning
Ventricular assist devices (VADs) are implanted in patients with a diseased ventricle to maintain peripheral perfusion as a bridge-to-transplant or as destination therapy. However, some patients with continuous flow VADs (e.g., HeartMate II (HMII)) have experienced gastrointestinal (GI) bleeding, in part caused by the proteolytic cleavage or mechanical destruction of von Willebrand factor (vWF), a clotting glycoprotein. in vitro studies were performed to measure the flow located within the HMII outlet cannula under both steady and physiological conditions using particle image velocimetry (PIV)...
July 1, 2018: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29689088/electrocardiogram-synchronized-pulsatile-extracorporeal-life-support-preserves-left-ventricular-function-and-coronary-flow-in-a-porcine-model-of-cardiogenic-shock
#8
Petr Ostadal, Mikulas Mlcek, Holger Gorhan, Ivo Simundic, Svitlana Strunina, Matej Hrachovina, Andreas Krüger, Dagmar Vondrakova, Marek Janotka, Pavel Hala, Martin Mates, Martin Ostadal, James C Leiter, Otomar Kittnar, Petr Neuzil
INTRODUCTION: Veno-arterial extracorporeal life support (ECLS) is increasingly being used to treat rapidly progressing or severe cardiogenic shock. However, it has been repeatedly shown that increased afterload associated with ECLS significantly diminishes left ventricular (LV) performance. The objective of the present study was to compare LV function and coronary flow during standard continuous-flow ECLS support and electrocardiogram (ECG)-synchronized pulsatile ECLS flow in a porcine model of cardiogenic shock...
2018: PloS One
https://www.readbyqxmd.com/read/29656786/numerical-investigation-of-band-spreading-generated-by-flow-through-needle-and-fixed-loop-sample-injectors
#9
Sander Deridder, Gert Desmet, Ken Broeckhoven
The present study reports on a computational fluid dynamics study of the band broadening occurring in injector systems frequently used in contemporary liquid chromatography instruments. The aim of this work is to determine band broadening originating purely from the injection volume in absence of any other possible contribution (e.g. band broadening due to the injection valve) and to unravel the mechanism behind it. Simulations of the dispersion process in flow through needle injectors were performed. In addition, fixed loop injectors were also simulated and comparison with flow through needle injectors was made...
June 1, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29590412/screening-spirometry-in-military-personnel-correlates-poorly-with-exercise-tolerance-and-asthma-history
#10
David M F Anderson, Nicholas R Ondrasik, Frederic A Rawlins, Joshua A Lospinoso, Thomas B Zanders, Michael J Morris
BACKGROUND: Spirometry is an easy-to-perform test for evaluating pulmonary symptoms but has several limitations to include adequate test performance for valid results. Spirometry is not recommended to screen a general population for evidence of pulmonary disease unless symptoms are present or longitudinal screening is done for potential occupational exposures. METHODS: A single-spirometry examination was performed on 900 active duty Army soldiers, ages 18-35 yr, without documented respiratory disease...
March 26, 2018: Military Medicine
https://www.readbyqxmd.com/read/29568740/feasibility-of-computational-fluid-dynamics-for-evaluating-the-intraventricular-hemodynamics-in-single-right-ventricle-based-on-echocardiographic-images
#11
Li-Jun Chen, Zhi-Rong Tong, Qian Wang, Yu-Qi Zhang, Jin-Long Liu
This study introduced a combined computational fluid dynamics (CFD) and echocardiography methodology to simulate blood flow in the single right ventricle (SRV) and normal ventricles to study the intraventricular flow. Derived from echocardiographic image loops, CFD-based three-dimensional (3D) flow models of normal subject's left ventricle (LV) and right ventricle (RV) and SRV with and without heart failure at three characteristic diastolic statuses were reconstructed. The CFD derived morphological and functional measurements in normal ventricles and the SRV were validated with echocardiography...
2018: BioMed Research International
https://www.readbyqxmd.com/read/29568152/comparative-piv-and-lda-studies-of-newtonian-and-non-newtonian-flows-in-an-agitated-tank
#12
Anna Story, Zdzisław Jaworski, Mark J Simmons, Emilia Nowak
The paper presents results of an experimental study of the fluid velocity field in a stirred tank equipped with a Prochem Maxflo T (PMT) type impeller which was rotating at a constant frequency of N  = 4.1 or 8.2 s-1 inducing transitional ( Re  = 499 or 1307) or turbulent ( Re  = 2.43 × 104 ) flow of the fluid. The experiments were performed for a Newtonian fluid (water) and a non-Newtonian fluid (0.2 wt% aqueous solution of carboxymethyl cellulose, CMC) exhibiting mild viscoelastic properties. Measurements were carried out using laser light scattering on tracer particles which follow the flow (2-D PIV)...
2018: Chemické Zvesti
https://www.readbyqxmd.com/read/29546045/ventilator-flow-data-predict-bronchopulmonary-dysplasia-in-extremely-premature-neonates
#13
Mariann H Bentsen, Trond Markestad, Thomas Halvorsen
Early prediction of bronchopulmonary dysplasia (BPD) may facilitate tailored management for neonates at risk. We investigated whether easily accessible flow data from a mechanical ventilator can predict BPD in neonates born extremely premature (EP). In a prospective population-based study of EP-born neonates, flow data were obtained from the ventilator during the first 48 h of life. Data were logged for >10 min and then converted to flow-volume loops using custom-made software. Tidal breathing parameters were calculated and averaged from ≥200 breath cycles, and data were compared between those who later developed moderate/severe and no/mild BPD...
January 2018: ERJ Open Research
https://www.readbyqxmd.com/read/29512293/adaptation-to-acute-pulmonary-hypertension-in-pigs
#14
Mare Mechelinck, Marc Hein, Sven Bellen, Rolf Rossaint, Anna B Roehl
The extent of right ventricular compensation compared to the left ventricle is restricted and varies among individuals, which makes it difficult to define. While establishing a model of acute pulmonary hypertension in pigs we observed two different kinds of compensation in our animals. Looking deeper into the hemodynamic data we tried to delineate why some animals could compensate and others could not. Pulmonary hypertension (mean pressure 45 mmHg) was induced gradually by infusion of a stable thromboxane A2 analogue U46619 in a porcine model (n = 22)...
March 2018: Physiological Reports
https://www.readbyqxmd.com/read/29480841/evaluation-of-the-anatomic-and-hemodynamic-abnormalities-in-tricuspid-atresia-before-and-after-surgery-using-computational-fluid-dynamics
#15
Li-Jun Chen, Yu-Qi Zhang, Zhi-Rong Tong, Ai-Min Sun
Analysis of hemodynamics inside tricuspid atresia (TA) chamber is essential to the understanding of TA for optimal treatment. In this study, we introduced a combined computational fluid dynamics (CFD) to simulate blood flow in the left ventricle (LV) to study the diastolic flow changes in TA.Real-time 3-dimentional echocardiography loops (ECHO) were acquired in normal control group, in TA patients before surgery (pre-op group) and after surgery (post-op group). ECHO loops were reconstructed and simulated by CFD, the geometric, volumetric changes, and vortices in the LV were studies and compare among 3 groups...
January 2018: Medicine (Baltimore)
https://www.readbyqxmd.com/read/29452928/comprehensive-on-line-two-dimensional-liquid-chromatography-%C3%A3-supercritical-fluid-chromatography-with-trapping-column-assisted-modulation-for-depolymerised-lignin-analysis
#16
Mingzhe Sun, Margareta Sandahl, Charlotta Turner
Lignin depolymerisation produces a large variety of low molecular weight phenolic compounds that can be upgraded to value-added chemicals. Detailed analysis of these complex depolymerisation mixtures is, however, hampered by the lack of resolving power of traditional analysis techniques. In this study, a novel online comprehensive two-dimensional reversed-phase liquid chromatography (RPLC) × supercritical fluid chromatography (SFC) method with trapping column interface was developed for the separation of phenolic compounds in depolymerised lignin samples...
March 16, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29437172/closed-loop-feedback-control-for-microfluidic-systems-through-automated-capacitive-fluid-height-sensing
#17
L R Soenksen, T Kassis, M Noh, L G Griffith, D L Trumper
Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1 mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations...
March 13, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/29405616/flow-volume-loops-measured-with-electrical-impedance-tomography-in-pediatric-patients-with-asthma
#18
Chuong Ngo, Falk Dippel, Klaus Tenbrock, Steffen Leonhardt, Sylvia Lehmann
BACKGROUND: Electrical impedance tomography (EIT) provides information on global and regional ventilation during tidal breathing and mechanical ventilation. During forced expiration maneuvers, the linearity of EIT and spirometric data has been documented in healthy persons. The present study investigates the potential diagnostic use of EIT in pediatric patients with asthma. METHODS: EIT and spirometry were performed in 58 children with asthma (average age ± SD: 11...
May 2018: Pediatric Pulmonology
https://www.readbyqxmd.com/read/29394944/windkessel-model-of-hemodynamic-state-supported-by-a-pulsatile-ventricular-assist-device-in-premature-ventricle-contraction
#19
Keun Her, Joon Yeong Kim, Ki Moo Lim, Seong Wook Choi
BACKGROUND: Counter-pulsation control (CPC) by ventricular assist devices (VADs) is believed to reduce cardiac load and increase coronary perfusion. However, patients with VADs have a higher risk of arrhythmia, which may cause the CPC to fail. Consequently, CPC has not been applied by VADs in clinical practice. The phase-locked loop (PLL) algorithm for CPC is readily implemented in VADs; however, it requires a normal, consistent heartbeat for adequate performance. When an arrhythmia occurs, the algorithm maintains a constant pumping rate despite the unstable heartbeat...
February 2, 2018: Biomedical Engineering Online
https://www.readbyqxmd.com/read/29365118/initial-in-vitro-testing-of-a-paediatric-continuous-flow-total-artificial-heart
#20
Kiyotaka Fukamachi, Jamshid H Karimov, David J Horvath, Gengo Sunagawa, Nicole A Byram, Barry D Kuban, Nader Moazami
OBJECTIVES: Mechanical circulatory support has become standard therapy for adult patients with end-stage heart failure; however, in paediatric patients with congenital heart disease, the options for chronic mechanical circulatory support are limited to paracorporeal devices or off-label use of devices intended for implantation in adults. Congenital heart disease and cardiomyopathy often involve both the left and right ventricles; in such cases, heart transplantation, a biventricular assist device or a total artificial heart is needed to adequately sustain both pulmonary and systemic circulations...
January 19, 2018: Interactive Cardiovascular and Thoracic Surgery
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