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https://www.readbyqxmd.com/read/28548693/hemodynamic-impact-of-the-c-pulse-cardiac-support-device-a-one-dimensional-arterial-model-study
#1
Daimé Campos Arias, Francisco Londono, Tania Rodríguez Moliner, Dimitrios Georgakopoulos, Nikos Stergiopulos, Patrick Segers
The C-Pulse is a novel extra-aortic counter-pulsation device to unload the heart in patients with heart failure. Its impact on overall hemodynamics, however, is not fully understood. In this study, the function of the C-Pulse heart assist system is implemented in a one-dimensional (1-D) model of the arterial tree, and central and peripheral pressure and flow waveforms with the C-Pulse turned on and off were simulated. The results were studied using wave intensity analysis and compared with in vivo data measured non-invasively in three patients with heart failure and with invasive data measured in a large animal (pig)...
May 26, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28547651/photoplethysmography-for-blood-volumes-and-oxygenation-changes-during-intermittent-vascular-occlusions
#2
T Y Abay, P A Kyriacou
Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO[Formula: see text]) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO[Formula: see text] for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated ([Formula: see text]HbO[Formula: see text]), reduced ([Formula: see text]HHb) and total haemoglobin ([Formula: see text]tHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions...
May 25, 2017: Journal of Clinical Monitoring and Computing
https://www.readbyqxmd.com/read/28547321/relationship-between-brain-pulsatility-and-cerebral-perfusion-pressure-replicated-validation-using-different-drivers-of-cpp-change
#3
Leanne A Calviello, Nicolás de Riva, Joseph Donnelly, Marek Czosnyka, Peter Smielewski, David K Menon, Frederick A Zeiler
BACKGROUND: Determination of relationships between transcranial Doppler (TCD)-based spectral pulsatility index (sPI) and pulse amplitude (AMP) of intracranial pressure (ICP) in 2 groups of severe traumatic brain injury (TBI) patients (a) displaying plateau waves and (b) with unstable mean arterial pressure (MAP). METHODS: We retrospectively reviewed patients with severe TBI and continuous TCD monitoring displaying either plateau waves or unstable MAP from 1992 to 1998...
May 25, 2017: Neurocritical Care
https://www.readbyqxmd.com/read/28547318/a-systematic-review-of-alpha-2-agonists-for-sedation-in-mechanically-ventilated-neurocritical-care-patients
#4
Alexandre Tran, Henrietta Blinder, Brian Hutton, Shane W English
The use of sedative medications is commonplace in intensive care units (ICUs) and an invaluable clinical tool for the intensive care physician. Sedation for critically ill, mechanically ventilated patients provides an opportunity to reduce anxiety, discomfort as well as ventilator intolerance and dyssynchrony. Alpha-2 agonists in particular have become increasingly popular for use in the neurocritical care population due to their proposed effectiveness in facilitating examinations and procedures as well as reducing the need for adjunctive agents...
May 25, 2017: Neurocritical Care
https://www.readbyqxmd.com/read/28547175/influence-of-body-mass-index-and-type-of-low-level-exercise-on-the-side-effect-profile-of-regadenoson
#5
Carlos Salgado-Garcia, Amelia Jimenez-Heffernan, Juana Lopez-Martin, Manuela Molina-Mora, Tarik Aroui, Elena Sanchez de Mora, Carlos Ramos-Font, Francisco Rivera de Los Santos, Carlos Ruiz-Frutos
PURPOSE: Regadenoson, an A2A adenosine receptor pharmacologic stress agent for radionuclide myocardial perfusion imaging (MPI), is administered as a single, fixed dose. We studied the side effect profile of regadenoson combined with two types of low-level exercise, according to body mass index (BMI). METHODS: Three hundred and fifty-six patients (46.1% men, mean age 67.7±10.7 years, range 31-90 years) underwent regadenoson stress testing combined with low-level exercise...
May 25, 2017: European Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/28545351/assessing-coronary-blood-flow-physiology-in-the-cardiac-catheterisation-laboratory
#6
Sethumadhavan Vijayan, David S Barmby, Ian R Pearson, Andrew G Davies, Stephen B Wheatcroft, Mohan Sivananthan
Contemporary management of coronary disease focuses on the treatment of stenoses in the major epicardial vessels. However, myocardial blood flow is known to be contingent on a range of factors in addition to the patency of the epicardial vessels. These include anatomical and physiological factors such as the extent of myocardium supplied by the vessel, systemic blood pressure, the natural variation in vascular tone in response to physiological needs which allows for coronary autoregulation and pathological factors such as the presence of downstream obstruction to flow due to disease of the small coronary vessels or myocardium...
May 24, 2017: Current Cardiology Reviews
https://www.readbyqxmd.com/read/28544543/acute-toll-like-receptor-4-activation-impairs-rat-renal-microvascular-autoregulatory-behaviour
#7
Justin P Van Beusecum, Shali Zhang, Anthony K Cook, Edward W Inscho
AIM: Little is known about how toll-like receptor 4 (TLR4) influences the renal microvasculature. We hypothesized that acute TLR4 stimulation with lipopolysaccharide (LPS) impairs afferent arteriole autoregulatory behaviour, partially through reactive oxygen species (ROS). METHODS: We assessed afferent arteriole autoregulatory behaviour after LPS treatment (1 mg kg(-1) ; i.p.) using the in vitro blood perfused juxtamedullary nephron preparation. Autoregulatory behaviour was assessed by measuring diameter responses to step-wise changes in renal perfusion pressure...
May 25, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28544033/impaired-neurovascular-reactivity-in-the-microvasculature-of-pregnant-women-with-preeclampsia
#8
Karine Ferreira Agra, Isabelle Eunice Albuquerque Pontes, José Roberto da Silva, José Natal Figueiroa, Geraldine F Clough, João Guilherme Bezerra Alves
Preeclampsia (PE) is associated with maternal vascular dysfunction, leading to serious cardiovascular risk both during and following pregnancy. OBJECTIVE: To assess microvascular reactivity in pregnant women with PE. METHODS: A cross-sectional study was performed in 36 pregnant women with PE and 36 normotensive pregnant women (C) in the third trimester. Skin microvascular blood flow was measured using laser Doppler flowmetry at rest (RF), during the maximum hyperaemic response to brief arterial occlusion (MF) and during the sympathetically-mediated constrictor response to deep inspiratory breath hold (IBH)...
May 19, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28542705/a-pump-free-microfluidic-3d-perfusion-platform-for-the-efficient-differentiation-of-human-hepatocyte-like-cells
#9
Louis Jun Ye Ong, Lor Huai Chong, Lin Jin, Pawan Kumar Singh, Poh Seng Lee, Hanry Yu, Abhishek Ananthanarayanan, Hwa Liang Leo, Yi-Chin Toh
The practical application of microfluidic liver models for in vitro drug testing is partly hampered by their reliance on human primary hepatocytes, which are limited in number and have batch-to-batch variation. Human stem cell-derived hepatocytes offer an attractive alternative cell source, although their 3D differentiation and maturation in a microfluidic platform have not yet been demonstrated. We develop a pump-free microfluidic 3D perfusion platform to achieve long-term and efficient differentiation of human liver progenitor cells into hepatocyte-like cells (HLCs)...
May 20, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28541891/critical-closing-pressure-during-controlled-increase-in-intracranial-pressure-comparison-of-three-methods
#10
Katarzyna Kaczmarska, Magdalena Kasprowicz, Agnieszka Uryga, Leanne Calviello, Georgios Varsos, Zofia Czosnyka, Marek Czosnyka
Critical closing pressure (CrCP) is the arterial blood pressure (ABP) threshold, below which small arterial vessels collapse and cerebral blood flow ceases. Here we aim to compare three methods for CrCPestimation in scenario of a controlled increase in intracranial pressure (ICP), induced by infusion tests performed in patients with suspected normal pressure hydrocephalus (NPH). METHODS: Computer recordings of directly-measured ICP, ABP and transcranial Doppler cerebral blood flow velocity (CBFV), from 37 NPH patients undergoing infusion tests, were retrospectively analyzed...
May 24, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28541158/noninvasive-optical-monitoring-of-critical-closing-pressure-and-arteriole-compliance-in-human-subjects
#11
Wesley B Baker, Ashwin B Parthasarathy, Kimberly P Gannon, Venkaiah C Kavuri, David R Busch, Kenneth Abramson, Lian He, Rickson C Mesquita, Michael T Mullen, John A Detre, Joel H Greenberg, Daniel J Licht, Ramani Balu, W Andrew Kofke, Arjun G Yodh
The critical closing pressure ( CrCP) of the cerebral circulation depends on both tissue intracranial pressure and vasomotor tone. CrCP defines the arterial blood pressure ( ABP) at which cerebral blood flow approaches zero, and their difference ( ABP -  CrCP) is an accurate estimate of cerebral perfusion pressure. Here we demonstrate a novel non-invasive technique for continuous monitoring of CrCP at the bedside. The methodology combines optical diffuse correlation spectroscopy (DCS) measurements of pulsatile cerebral blood flow in arterioles with concurrent ABP data during the cardiac cycle...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28540736/effects-of-diesel-exhaust-on-cardiovascular-function-and-oxidative-stress
#12
Simon Wilson, Mark R Miller, David E Newby
SIGNIFICANCE: Air pollution is a major global health concern with the particulate matter (PM) being especially associated with marked increases in cardiovascular morbidity and mortality. Diesel exhaust emissions are a particularly rich source of the smallest sizes of PM ("fine" and "ultrafine") in urban environments, and it is these particles that are believed to be the most detrimental to cardiovascular health. Recent Advances: Controlled exposure studies to diesel exhaust in animals and man demonstrate alterations in blood pressure, heart rate, vascular tone, endothelial function, myocardial perfusion, thrombosis, atherogenesis and plaque stability...
May 25, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/28540010/changes-in-choroidal-perfusion-after-orbital-decompression-surgery-for-graves-ophthalmopathy
#13
Narieman Nik, Amelia Fong, Marianna Derdzakyan, Chrysavgi Adamopoulou, Adam Sise, Aziz Khanifar, Reginald Sanders
PURPOSE: To assess choroidal perfusion before and after orbital decompression surgery in patients with Graves' ophthalmopathy. METHODS: In this interventional case series, surgical decompression for optic nerve compromise was performed on four eyes of three patients with Graves' disease. Complete ophthalmic examination including visual acuity, color vision, and intraocular pressure assessment were done pre- and postoperatively. High-speed indocyanine green angiography was performed prior to surgery and was repeated one year after surgery...
April 2017: Journal of Ophthalmic & Vision Research
https://www.readbyqxmd.com/read/28539354/cerebral-oxygenation-and-regional-cerebral-perfusion-responses-with-resistance-breathing-during-central-hypovolemia
#14
Victoria L Kay, Justin Daniel Sprick, Caroline A Rickards
Resistance breathing improves tolerance to central hypovolemia induced by lower body negative pressure (LBNP), but this is not related to protection of anterior cerebral blood flow (indexed by mean middle cerebral artery velocity, MCAv). We hypothesized that inspiratory resistance breathing improves tolerance to central hypovolemia by maintaining cerebral oxygenation (ScO2), and protecting cerebral blood flow in the posterior cerebral circulation (indexed by posterior cerebral artery velocity, PCAv). Eight subjects (4M/4F) completed two experimental sessions of a presyncopal-limited LBNP protocol (3 mmHg/min onset rate) with and without (Control) resistance breathing via an impedance threshold device (ITD)...
May 24, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28538235/what-should-we-do-about-low-blood-pressure-in-preterm-infants
#15
Eugene M Dempsey
The management of preterm infants with low blood pressure soon after birth remains unresolved. The definition of what constitutes low blood pressure is uncertain. At birth, mean blood pressure appears to be gestation specific and increases in the first few days of life. Antenatal steroids, delayed cord clamping, and the avoidance of mechanical ventilation are all associated with higher mean blood pressure and less hypotension after birth. Rates of hypotension of 15-50% have been reported in various studies of extremely preterm infants...
2017: Neonatology
https://www.readbyqxmd.com/read/28537998/lactate-and-microcirculation-as-suitable-targets-for-hemodynamic-optimization-in-resuscitation-of-circulatory-shock
#16
Michael E Kiyatkin, Jan Bakker
PURPOSE OF REVIEW: A discussion of recent research exploring the feasibility of perfusion-guided resuscitation of acute circulatory failure with a focus on lactate and microcirculation. RECENT FINDINGS: Upon diagnosis of shock, hyperlactemia is associated with poor outcome and, under appropriate clinical circumstances, may reflect inadequate tissue perfusion. Persistent hyperlactemia despite resuscitation is even more strongly correlated with morbidity and mortality...
May 22, 2017: Current Opinion in Critical Care
https://www.readbyqxmd.com/read/28536944/fluid-responsiveness-predicted-by-transcutaneous-partial-pressure-of-oxygen-in-patients-with-circulatory-failure-a-prospective-study
#17
Jingyuan Xu, Xiao Peng, Chun Pan, Shixia Cai, Xiwen Zhang, Ming Xue, Yi Yang, Haibo Qiu
BACKGROUND: Significant effort has been devoted to defining parameters for predicting fluid responsiveness. Our goal was to study the feasibility of predicting fluid responsiveness by transcutaneous partial pressure of oxygen (PtcO2) in the critically ill patients. METHODS: This was a single-center prospective study conducted in the intensive care unit of a tertiary care teaching hospital. Shock patients who presented with at least one clinical sign of inadequate tissue perfusion, defined as systolic blood pressure <90 mmHg or a decrease >40 mmHg in previously hypertensive patients or the need for vasopressive drugs; urine output <0...
December 2017: Annals of Intensive Care
https://www.readbyqxmd.com/read/28536897/validation-of-myocardial-perfusion-quantification-by-dynamic-ct-in-an-ex-vivo-porcine-heart-model
#18
Gert Jan Pelgrim, Marco Das, Sjoerd van Tuijl, Marly van Assen, Frits W Prinzen, Marco Stijnen, Matthijs Oudkerk, Joachim E Wildberger, Rozemarijn Vliegenthart
To test the accuracy of quantification of myocardial perfusion imaging (MPI) using computed tomography (CT) in ex-vivo porcine models. Five isolated porcine hearts were perfused according to Langendorff. Hearts were perfused using retrograde flow through the aorta and blood flow, blood pressure and heart rate were monitored throughout the experiment. An inflatable cuff was placed around the circumflex (Cx) artery to create stenosis grades which were monitored using a pressure wire, analysing perfusion at several fractional flow reserve values of 1...
May 23, 2017: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/28536207/impaired-cerebral-autoregulation-measurement-and-application-to-stroke
#19
REVIEW
Li Xiong, Xiuyun Liu, Ty Shang, Peter Smielewski, Joseph Donnelly, Zhen-Ni Guo, Yi Yang, Thomas Leung, Marek Czosnyka, Rong Zhang, Jia Liu, Ka Sing Wong
Cerebral autoregulation (CA) is a protective mechanism that maintains cerebral blood flow at a relatively constant level despite fluctuations of cerebral perfusion pressure or arterial blood pressure. It is a universal physiological mechanism that may involve myogenic, neural control as well as metabolic regulations of cerebral vasculature in response to changes in pressure or cerebral blood flow. Traditionally, CA has been represented by a sigmoid curve with a wide plateau between about 50 mm Hg and 170 mm Hg of steady-state changes in mean arterial pressure, defined as static CA...
June 2017: Journal of Neurology, Neurosurgery, and Psychiatry
https://www.readbyqxmd.com/read/28535788/endexpiratory-lung-volume-measurement-correlates-with-the-ventilation-perfusion-mismatch-in-lung-injured-pigs
#20
Jens Kamuf, Andreas Garcia-Bardon, Bastian Duenges, Tanghua Liu, Antje Jahn-Eimermacher, Florian Heid, Matthias David, Erik K Hartmann
BACKGROUND: In acute respiratory respiratory distress syndrome (ARDS) a sustained mismatch of alveolar ventilation and perfusion (VA/Q) impairs the pulmonary gas exchange. Measurement of endexpiratory lung volume (EELV) by multiple breath-nitrogen washout/washin is a non-invasive, bedside technology to assess pulmonary function in mechanically ventilated patients. The present study examines the association between EELV changes and VA/Q distribution and the possibility to predict VA/Q normalization by means of EELV in a porcine model...
May 23, 2017: Respiratory Research
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