scholarly journals A study on short-time dialysis (initial report). Focus on the effect of high shunt blood flow on cardiac functions.

1993 ◽  
Vol 26 (10) ◽  
pp. 1615-1620
Author(s):  
Satoru Kuriyama ◽  
Kayoko Matsui ◽  
Yasunori Utsunomiya ◽  
Haruo Tomonari
Keyword(s):  
Blood Flow ◽  
Initial Report ◽  
Cardiac Functions ◽  
Short Time

scholarly journals Magnetohydrodynamic Blood Flow in a Cylindrical Tube with Magnetic Particles: A Time Fractional Model

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Farhad Ali ◽  
Samina Majeed ◽  
Anees Imtiaz
Keyword(s):  
Blood Flow ◽  
Magnetic Particles ◽  
Mass Parameter ◽  
Classical Model ◽  
Cylindrical Tube ◽  
Definition Of ◽  
Circular Cylindrical Tube ◽  
Short Time ◽  
Applied External Magnetic Field ◽  
Fractional Parameter

The present work theoretically investigates the natural convection blood flow as a Brinkman-type fluid with uniformly distributed magnetic particles in a circular cylindrical tube with the applied external magnetic field. The classical model for the blood flow is generalized by using the definition of Caputo time-fractional derivative. The exact solutions are obtained by using the Laplace and Henkel transforms. Unlike the classical model, the obtained general results are expressed in the form of “Lorenzo and Hartley’s” and “Robotnov and Hartley’s” functions. Graphs are plotted to show the effects of different parameters on the blood flow. Furthermore, the velocity and temperature distributions are discussed in terms of memory. The effect of fractional parameter α for a long and short time has also been observed. It is noticed that blood velocity can be controlled using the fractional parameter. It is also found that, for τ > 0 , fluid and particles motion increased, and reverse behavior is observed for τ < 0 . It has been noticed that increasing values of particle mass parameter P m and magnetic parameter M slow down the motion of blood and magnetic particles. These results are helpful for effective drug delivery and regulating blood flow.

scholarly journals Optical endovascular imaging combining endoscopy, NBI and OCT, a feasibility study

2019 ◽  
Vol 5 (1) ◽  
pp. 577-580
Author(s):  
Axel Boese ◽  
Akhil Karthasseril Sivankutty ◽  
Michael Friebe
Keyword(s):  
Blood Flow ◽  
Structural Information ◽  
Endoscopic Imaging ◽  
Camera System ◽  
Video Mode ◽  
Endoscopic Images ◽  
System A ◽  
Analysis Of The Images ◽  
Definition Of ◽  
Short Time

AbstractFor imaging of the vascular structure, angiography is state of the art. This can be done by contrast enhanced XRay, CT or MR imaging. But these modalities typically only show the blood flow and do not allow a depiction of the vasculature itself. To provide information about the vessel walls and plaques narrowing the blood flow, catheter based intra vascular ultrasound or vascular optical coherence tomography can be used. Optical endoscopic imaging is rarely used in vascular diagnosis. But endoscopic imaging can depict superficial inflammations or defects of the intima vessel layer and the real anatomical shape of the inner vasculature e.g. at bifurcations or aneurysms. Since OCT and endoscopic imaging both need a flushing to remove the blood for a short time, a combination of both modalities seems viable. For combining the two modalities, various background studies were performed including the selection of a feasible fibre endoscope, light source and camera system. A new pull-back and flushing device was designed and created for realizing the synchronous image acquisition using the two modalities. For calibration of the system and definition of the pullback and imaging parameters, first tests on artificial phantoms were performed. Then vascular and tissue models were imaged in a combined pullback mode after using the flush for complete blood removal. Endoscopic images were acquired in a video mode. The analysis of the images was done subjectively. As expected, the OCT provided structural information of the wall. The endoscopic images in combination with pullback appear blurry in video mode. The flushing liquid hinders the automatic focusing of the camera. Thus, smaller details could not be identified but bifurcations were visible. Even though the results were not good as expected, the study showed the potential of a bimodal system and addressed the issues faced in the initial implementation.

scholarly journals THE STATE OF THE VESSELS OF THE MESENTERY IN SHOCK PRODUCED BY CONSTRICTING THE LIMBS AND THE BEHAVIOR OF THE VESSELS FOLLOWING HEMORRHAGE

1943 ◽  
Vol 77 (3) ◽  
pp. 215-232 ◽  
Author(s):  
Irvine H. Page ◽  
Richard G. Abell
Keyword(s):  
Blood Flow ◽  
Venous Return ◽  
Muscular Contraction ◽  
The Body ◽  
Moderate Degree ◽  
Bilateral Nephrectomy ◽  
Direct Observations ◽  
Morphological Picture ◽  
Incomplete Occlusion ◽  
Short Time

1. Direct observations of the arteries, arterioles, capillaries, veins, and lymphatics in the mesentery of anesthetized cats put into shock by incomplete occlusion of the circulation of the limbs showed that: (a) Marked constriction of the arteries and arterioles, produced by muscular contraction, occurred usually within an hour after incomplete occlusion of the limbs, lasted several hours, and finally gave way in most instances to relaxation an hour or more before death. The constriction reduced the blood supply to the mesentery and intestine and the venous return from them. It did not, however, interrupt the blood flow. No pooling or stagnation of blood was seen even as a terminal phenomenon. (b) The veins of the mesentery also became constricted but showed less tendency to dilate as death approached. The lymphatics likewise became somewhat narrowed. Even during the terminal stage the leukocytes moved along without change in shape or sticking to the walls of the capillaries or venules. (c) Hematocrit determinations showed progressive hemoconcentration of moderate degree. (d) Autopsy usually showed the presence of small hemorrhages in many parts of the body, especially the heart, liver, spleen, and lungs. (e) Bilateral nephrectomy, suprarenalectomy, and pancreatectomy did not significantly alter the morphological picture elicited by shock induced by restriction of the circulation to the limbs. 2. Removal of large amounts of blood was always followed within a short time by constriction of arteries, arterioles, veins, and lymphatics of the mesentery. 3. Fall in arterial pressure produced by pithing was not accompanied by change in diameter of the arteries, arterioles, veins, or lymphatics, or by blanching of the mesentery or gut.

Cardiovascular Response to Glucagon in Hypovolemic Dogs

1975 ◽  
Vol 53 (2) ◽  
pp. 211-216
Author(s):  
G. Pinardi ◽  
E. Santiago ◽  
J. V. Vasquez
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Myocardial Metabolism ◽  
Cardiovascular Response ◽  
Cardiovascular Effects ◽  
Aortic Blood Flow ◽  
Vascular Effects ◽  
Control Value ◽  
Cardiac Depression ◽  
Short Time

Glucagon in a dose of 50 μg/kg body weight was studied for its cardiovascular effects in hypovolemic dogs in which coronary blood flow was reduced to an average of 40% of its control value and cardiac depression was evident. Myocardial contractility, as judged mainly by dP/dt and acceleration of aortic blood flow, was brought to a normal level for a short time. Systemic and coronary vascular resistances were markedly reduced. These effects were similar in normovolemic dogs. The inotropic, chronotropic, and peripheral vascular effects of glucagon can be evoked also in hypovolemic dogs in which coronary blood flow is less than normal and myocardial metabolism is impaired.

Independent cerebral vasoconstrictive effects of hyperoxia and accompanying arterial hypocapnia at 1 ATA

2003 ◽  
Vol 95 (6) ◽  
pp. 2453-2461 ◽  
Author(s):  
Thomas F. Floyd ◽  
James M. Clark ◽  
Robert Gelfand ◽  
John A. Detre ◽  
Sarah Ratcliffe ◽  
...  
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Blood Gases ◽  
Arterial Blood Gases ◽  
Response Curves ◽  
Healthy Men ◽  
Cerebral Vasoconstriction ◽  
Arterial Blood ◽  
Short Time ◽  
Time Frames

Breathing 100% O2 at 1 atmosphere absolute (ATA) is known to be associated with a decrease in cerebral blood flow (CBF). It is also accompanied by a fall in arterial Pco2 leading to uncertainty as to whether the cerebral vasoconstriction is totally or only in part caused by arterial hypocapnia. We tested the hypothesis that the increase in arterial Po2 while O2 was breathed at 1.0 ATA decreases CBF independently of a concurrent fall in arterial Pco2. CBF was measured in seven healthy men aged 21–62 yr by using noninvasive continuous arterial spin-labeled-perfusion MRI. The tracer in this technique, magnetically labeled protons in blood, has a half-life of seconds, allowing repetitive measurements over short time frames without contamination. CBF and arterial blood gases were measured while breathing air, 100% O2, and 4 and 6% CO2 in air and O2 backgrounds. Arterial Po2 increased from 91.7 ± 6.8 Torr in air to 576.7 ± 18.9 Torr in O2. Arterial Pco2 fell from 43.3 ± 1.8 Torr in air to 40.2 ± 3.3 Torr in O2. CBF-arterial Pco2 response curves for the air and hyperoxic runs were nearly parallel and separated by a distance representing a 28.7–32.6% decrement in CBF. Regression analysis confirmed the independent cerebral vasoconstrictive effect of increased arterial Po2. The present results also demonstrate that the magnitude of this effect at 1.0 ATA is greater than previously measured.

scholarly journals Eliminating Vascular Obstruction in Myocardial Infarction by Accelerated Ferromagnetic Microrobot

2021 ◽  
Author(s):  
Abbas Moghanizadeh ◽  
Milad Khanzadi ◽  
Mandana Rajabi
Keyword(s):  
Myocardial Infarction ◽  
Blood Flow ◽  
Artificial Graft ◽  
Blood Clots ◽  
Micro Robot ◽  
Vascular Obstruction ◽  
Short Time ◽  
Unique Potential ◽  
The Magnetic Field

Abstract Background vascular obstruction by clots is one of the main reasons of cardiovascular disease such as myocardial infarction. There is a short time, less than 6 minutes, to establish the blood flow, especially in vital organs. While conventional techniques are not very fast and effective, current micro-robots have inherent limitations such as being slow to achieving this goal. Objective There is a strong requirement to develop microrobots with new principles that can quickly eliminate clot blockage in the vascular. The aim of this study is to evaluate, in-vitro, the efficiency of accelerated ferromagnetic micro-robots in destroying blood clots in an artificial vascular precipitately. Methods An artificial graft with a diameter of 10 mm were used as the vessel. Blood clots with various lengths (5*10 and 10*10 and 20*10mm3 (dimeter*length)) are formed inside the graft. Microrobots made of steel with a length of 1 mm and a width of 0.05 mm are utilized. Besides, an electromagnetic accelerator is prototyped to instantly raise the magnetic field, which accelerates the magnetic micro-robot toward the blocked artery. Blood clots with various lengths (5*10 and 10*10 and 20*10mm3(Dimeter*length)) are formed inside the tube. The effect of voltage from 100 to 400 volts on destroying different lengths of clot has been studied. Results The microrobot enables to destroy the clot and reopen the vessel in a fraction of a second. By increasing the voltage from 100 to 400 volt, the micro-robot is able to destroy clots with longer lengths from 5 to 30 mm. Conclusion results confirm that accelerated microbes have a unique potential in piercing clots to reestablish blood flow.

scholarly journals Assessment of the Influence of Hyperechogenic Focus Detected on Fetal Echocardiographic Examination on Cardiac Functions Through Analyzing Ductus Venous Blood Flow

2014 ◽  
Vol 1 (4) ◽  
pp. 203-206
Author(s):  
Yılmaz Yozgat ◽  
Rahmi Özdemir ◽  
Cem Karadeniz ◽  
Seçil Kurtulmuş ◽  
Mustafa Demirol ◽  
...  
Keyword(s):  
Blood Flow ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Cardiac Functions ◽  
Echocardiographic Examination

scholarly journals Toward the Implementation of Contemplative Practices in Higher Education

2018 ◽  
Vol 6 (3) ◽  
pp. 3-13
Author(s):  
Valerie Bonnardel ◽  
Terry Biddington ◽  
Brandon May ◽  
Rhiannon Jones ◽  
Simon Roffey
Keyword(s):  
Higher Education ◽  
Mobile Technologies ◽  
Initial Report ◽  
Contemplative Practices ◽  
Learning And Teaching ◽  
Contemplative Pedagogy ◽  
Use Of Technology ◽  
The Mind ◽  
The University ◽  
Short Time

Endorsing the role of Universities as caregiving organisations and following an initial report on contemplative practices (CP) in Higher Education by the Institute of Theological Partnerships (2016) and the Mindful Nation UK (2015), a Contemplative Pedagogy Working Group (CPWG) was convened to explore the possibilities to implement contemplative pedagogy and practices at the University. CP such as Buddhist meditation have direct bearings in developing and cultivating compassion. With the intention to foster a culture of gentleness within the University, a survey was administered to 301 students to: 1- probe their attitudes toward the introduction of CP at the University and 2- to collect information on their use of technology. Results indicate that 79% of students will be favourable to the introduction of CP at the University on a voluntary basis and 58% will be keen to engage with the practice. However, if short time practices were to be introduced in classes, 44% will be self-conscious and admit it will affect their practice. Seventy percent admit difficulty with their attention during lectures and exam revisions and 58% are distracted by mobile technologies used in classes, report of distractibility is more marked among the youngest. The survey’s result highlights student’s tendency to consider learning about CP in relation to the mind and emotions should be part of their education. This awareness is indicative of a change in students’ expectation and support the CPWG initiatives in offering regular Zen meditation practices and building up a Cosmic Garden within the University premises. Challenges in fostering a compassionate learning and teaching environment and concerns related to the pervasive use of technology in classes, in particular the correlation between the variety of online multitasking and the worry of feeling self-conscious during CP will be discussed.

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