Dual turbine power plant and a reheat steam bypass flow control system for use therein

International Nuclear Information System (INIS)

Braytenbah, A.S.; Jaegtnes, K.O.

1977-01-01

An electric power plant having dual turbine-generators connected to a steam source that includes a high temperature gas cooled nuclear reactor is described. Each turbine comprises a high pressure portion operated by superheat steam and an intermediate-low pressure portion operated by reheat steam; a bypass line is connected across each turbine portion to permit a desired minimum flow of steam from the source at times when the combined flow of steam through the turbine is less than the minimum. Coolant gas is propelled through the reactor by a circulator which is driven by an auxiliary turbine which uses steam exhausted from the high pressure portions and their bypass lines. The pressure of the reheat steam is controlled by a single proportional-plus-integral controller which governs the steam flow through the bypass lines associated with the intermediate-low pressure portions. At times when the controller is not in use its output signal is limited to a value that permits an unbiased response when pressure control is resumed, as in event of a turbine trip. 25 claims, 2 figures

A CFD method to evaluate the integrated influence of leakage and bypass flows on the PBMR Reactor Unit

International Nuclear Information System (INIS)

Janse van Rensburg, J.J.; Kleingeld, M.

2010-01-01

Research highlights: → Research and analysis to identify and rank different leakage flow paths in a HTR. → Development of integrated CFD methodology for the prediction of leakage flows. → Development of a methodology to simulate flow resistances in above CFD model. → Validation of predicted flow results against different numerical methodology. → Illustration of the significant improvement achieved through this methodology. - Abstract: An area that has been identified as significantly important in the development of a High Temperature Reactor (HTR) is the prediction of leakage and bypass flows through such a reactor. It is therefore essential to understand the causes of bypass flows and to determine the effect on the predicted fuel and component temperatures. This paper discusses the identification of leakage flows that are applicable to the Pebble Bed Modular Reactor (Pty) Ltd. (PBMR) design and the ranking of these leakage flows. The modeling methodology and results are also discussed. Similar to previous HTR's, it was found that leakage and bypass flows are important parameters to consider for safe and efficient operation of the PBMR. Through a focused approach, it is shown that PBMR is able to improve the understanding of this phenomenon and quantify the flows and subsequent influence on the operation of the system. This has resulted in a reduction of leakage and bypass from approximately 46% to 20%. The improved understanding of leakage and bypass flows allows PBMR to address this issue during the design phase of the project, which subsequently results in a vast improvement over historical HTR designs. This gives PBMR a distinct advantage over previous High Temperature Reactors.

VALIDATION OF NUMERICAL METHODS TO CALCULATE BYPASS FLOW IN A PRISMATIC GAS-COOLED REACTOR CORE

Directory of Open Access Journals (Sweden)

NAM-IL TAK

2013-11-01

Full Text Available For thermo-fluid and safety analyses of a High Temperature Gas-cooled Reactor (HTGR, intensive efforts are in progress in the developments of the GAMMA+ code of Korea Atomic Energy Research Institute (KAERI and the AGREE code of the University of Michigan (U of M. One of the important requirements for GAMMA+ and AGREE is an accurate modeling capability of a bypass flow in a prismatic core. Recently, a series of air experiments were performed at Seoul National University (SNU in order to understand bypass flow behavior and generate an experimental database for the validation of computer codes. The main objective of the present work is to validate the GAMMA+ and AGREE codes using the experimental data published by SNU. The numerical results of the two codes were compared with the measured data. A good agreement was found between the calculations and the measurement. It was concluded that GAMMA+ and AGREE can reliably simulate the bypass flow behavior in a prismatic core.

Flow Simulation of Supersonic Inlet with Bypass Annular Duct

Science.gov (United States)

Kim, HyoungJin; Kumano, Takayasu; Liou, Meng-Sing; Povinelli, Louis A.; Conners, Timothy R.

2011-01-01

A relaxed isentropic compression supersonic inlet is a new concept that produces smaller cowl drag than a conventional inlet, but incurs lower total pressure recovery and increased flow distortion in the (radially) outer flowpath. A supersonic inlet comprising a bypass annulus to the relaxed isentropic compression inlet dumps out airflow of low quality through the bypass duct. A reliable computational fluid dynamics solution can provide considerable useful information to ascertain quantitatively relative merits of the concept, and further provide a basis for optimizing the design. For a fast and reliable performance evaluation of the inlet performance, an equivalent axisymmetric model whose area changes accounts for geometric and physical (blockage) effects resulting from the original complex three-dimensional configuration is proposed. In addition, full three-dimensional calculations are conducted for studying flow phenomena and verifying the validity of the equivalent model. The inlet-engine coupling is carried out by embedding numerical propulsion system simulation engine data into the flow solver for interactive boundary conditions at the engine fan face and exhaust plane. It was found that the blockage resulting from complex three-dimensional geometries in the bypass duct causes significant degradation of inlet performance by pushing the terminal normal shock upstream.

Experimental investigations of the steady flow through an idealized model of a femoral artery bypass

Directory of Open Access Journals (Sweden)

Giurgea Corina

2014-03-01

Full Text Available The present paper presents the steps taken by the authors in the first stage of an experimental program within a larger national research project whose objective is to characterize the flow through a femoral artery bypass with a view to finding solutions for its optimization. The objective of the stage is to investigate by means of the PIV method the stationary flow through a bypass model with an idealized geometry. A bypass assembly which reunites the idealized geometry models of the proximal and distal anastomoses, and which respects the lengths of a femoral artery bypass was constructed on the basis of data for a real patient provided by medical investigations. With the aim of testing the model and the established experimental set-up with regard to their suitability for the assessment of the velocity field associated to the steady flow through the bypass, three zones that can restore the whole distal anastomosis were PIV investigated. The measurements were taken in the conditions of maintained inflow at the bypass entry of 0.9 l / min (Re = 600. The article presents comparatively the flow spectra and the velocity fields for each zone obtained in two situations: with the femoral artery completely occluded and completely open.

Effect of age on cerebral blood flow during hypothermic cardiopulmonary bypass

International Nuclear Information System (INIS)

Brusino, F.G.; Reves, J.G.; Smith, L.R.; Prough, D.S.; Stump, D.A.; McIntyre, R.W.

1989-01-01

Cerebral blood flow was measured in 20 patients by xenon 133 clearance methodology during nonpulsatile hypothermic cardiopulmonary bypass to determine the effect of age on regional cerebral blood flow during these conditions. Measurements of cerebral blood flow at varying perfusion pressures were made in patients arbitrarily divided into two age groups at nearly identical nasopharyngeal temperature, hematocrit value, and carbon dioxide tension and with equal cardiopulmonary bypass flows of 1.6 L/min/m2. The range of mean arterial pressure was 30 to 110 mm Hg for group I (less than or equal to 50 years of age) and 20 to 90 mm Hg for group II (greater than or equal to 65 years of age). There was no significant difference (p = 0.32) between the mean arterial pressure in group I (54 +/- 28 mm Hg) and that in group II (43 +/- 21 mm Hg). The range of cerebral blood flow was 14.8 to 29.2 ml/100 gm/min for group I and 13.8 to 37.5 ml/100 gm/min for group II. There was no significant difference (p = 0.37) between the mean cerebral blood flow in group I (21.5 +/- 4.6 ml/100 gm/min) and group II (24.3 +/- 8.1 ml/100 gm/min). There was a poor correlation between mean arterial pressure and cerebral blood flow in both groups: group I, r = 0.16 (p = 0.67); group II, r = 0.5 (p = 0.12). In 12 patients, a second cerebral blood flow measurements was taken to determine the effect of mean arterial pressure on cerebral blood flow in the individual patient. Changes in mean arterial pressure did not correlate with changes in cerebral blood flow (p less than 0.90). We conclude that age does not alter cerebral blood flow and that cerebral blood flow autoregulation is preserved in elderly patients during nonpulsatile hypothermic cardiopulmonary bypass

Evaluation of the influence of bypass flow gap distribution on the core hot spot in a prismatic VHTR core

International Nuclear Information System (INIS)

Kim, Min-Hwan; Lim, Hong-Sik

2011-01-01

Highlights: → A procedure to evaluate the local gap size variation between graphite blocks was developed and applied to a prismatic core VHTR. → The analysis for the core bypass flow and hot spot was carried out based on the calculated gap distributions. → The predicted gap size is large enough to affect the flow distribution in the core. → The bypass gap and flow distributions are closely related to the local hot spot temperature and its location. → The core restraint mechanism preventing outward movement of graphite block reduces the bypass gap size and hot spot temperature. - Abstract: Core bypass flow in VHTR is one of the key issues for core thermal margins and efficiency. The bypass flow in the prismatic core varies during core cycles due to the irradiation shrinkage/swelling and thermal expansion of the graphite blocks. A procedure to evaluate the local gap size variation between graphite blocks was developed and applied to a prismatic core VHTR. The influence of the core restraint mechanism on the bypass flow gap was evaluated. The predicted gap size is as much as 8 mm when the graphite block is exposed to its allowable limit of fast neutron fluence. The analysis for the core bypass flow and hot spot was carried out based on the calculated gap distributions. The results indicate that the bypass gap and flow distributions are closely related to the local hot spot and its location and the core restraint mechanism preventing outward movement of the graphite block by a fastening device reduces the bypass gap size, which results in the decrease of maximum fuel temperature not less than 100 deg. C, when compared to the case without it.

Experimental study of bypass flow in near wall gaps of a pebble bed reactor using hot wire anemometry technique

International Nuclear Information System (INIS)

Amini, Noushin; Hassan, Yassin A.

2014-01-01

Highlights: • Coolant flow behavior in near wall gaps of a pebble bed reactor is studied. • Hot wire anemometry is applied for high frequency velocity measurements. • Bypass flow is identified within the velocity profiles of near wall gaps. • Effect of gap geometry and Reynolds number on bypass flow is investigated. • Variation of velocity power spectra with radial location and Reynolds number is studied. - Abstract: Coolant flow behavior through the core of an annular pebble bed reactor is investigated in this experimental study. A high frequency hot wire anemometry system coupled with an X-probe is used for measurement of axial and radial velocity components at different points within two near wall gaps at five different modified Reynolds numbers (Re m = 2043–6857). The velocity profiles within the gaps verify the presence of an area of increased velocity close to the pebble bed outer reflector wall, which is known as the bypass flow. Moreover, the characteristics of the coolant flow profile are seen to be highly dependent on the gap geometry. The effect of Reynolds number on the velocity profiles varies as the geometry of the gap changes. The time histories of the local velocities measured with considerably high frequency are further analyzed using power spectral density technique. Power spectral plots illustrate substantial spatial variation of the energy content, spectral shape, and the slope of the energy cascade region. A significant correlation between Reynolds number and characteristics of the velocity power spectra is observed

Testing and Performance Verification of a High Bypass Ratio Turbofan Rotor in an Internal Flow Component Test Facility

Science.gov (United States)

VanZante, Dale E.; Podboy, Gary G.; Miller, Christopher J.; Thorp, Scott A.

2009-01-01

A 1/5 scale model rotor representative of a current technology, high bypass ratio, turbofan engine was installed and tested in the W8 single-stage, high-speed, compressor test facility at NASA Glenn Research Center (GRC). The same fan rotor was tested previously in the GRC 9x15 Low Speed Wind Tunnel as a fan module consisting of the rotor and outlet guide vanes mounted in a flight-like nacelle. The W8 test verified that the aerodynamic performance and detailed flow field of the rotor as installed in W8 were representative of the wind tunnel fan module installation. Modifications to W8 were necessary to ensure that this internal flow facility would have a flow field at the test package that is representative of flow conditions in the wind tunnel installation. Inlet flow conditioning was designed and installed in W8 to lower the fan face turbulence intensity to less than 1.0 percent in order to better match the wind tunnel operating environment. Also, inlet bleed was added to thin the casing boundary layer to be more representative of a flight nacelle boundary layer. On the 100 percent speed operating line the fan pressure rise and mass flow rate agreed with the wind tunnel data to within 1 percent. Detailed hot film surveys of the inlet flow, inlet boundary layer and fan exit flow were compared to results from the wind tunnel. The effect of inlet casing boundary layer thickness on fan performance was quantified. Challenges and lessons learned from testing this high flow, low static pressure rise fan in an internal flow facility are discussed.

Advanced DVI for ECC direct bypass mitigation

International Nuclear Information System (INIS)

Kwon, Tae-Soon; Song, Chul-Hwa; Baek, Won-Pil

2009-01-01

An ECC direct bypass fraction during a late reflood phase of a LBLOCA is strongly dependent on the characteristics of the cross flow and the geometrical configuration of a DVI in the downcomer of a pressurized light water reactor. The important design parameters of a DVI are the elevation, the azimuthal angle, and the separator to prevent a steam-water interaction. An ECC sub-channel to separate or to isolate an ECC water from a high-speed cross flow is one of the important design features to mitigate the ECC bypass phenomena. A dual core barrel cylinder as an ECC flow separator is located between a reactor vessel and a core barrel outer wall in the downcomer annulus. A new narrow gap between the core barrel and the additional dual core barrel plays the role of a downward ECC flow channel or an ECC flow separator in a high-speed cross flow field of the downcomer annulus. The flow zone around a broken cold leg in the downcomer annulus has the role of a high ECC direct bypass due to a strong suction force while the wake zone of a hot leg has the role of an ECC penetration. Thus, the relative azimuthal angle of the DVI nozzle from the broken cold leg is an important design parameter. A large azimuthal angle from a cold leg to a hot leg needs to avoid a high suction flow zone when an ECC water is being injected. The other enhancing mechanism of an ECC penetration is a grooved core barrel which has small rectangular-shaped grooves vertically arranged on the core barrel wall of the reactor vessel downcomer annulus. These grooves have the role for a generation of a vortex induced by a high-speed cross flow. Since the stagnant flow in a lateral direction and rotational vortex provides the pulling force of an ECC drop or film to flow down into the lower downcomer annulus by gravity, the ECC direct bypass fraction is reduced when compared to the current design of a smoothed wall. An open channel of grooves generates a stagnant vortex, while a closed channel of grooves

Dopexamine increases internal mammary artery blood flow following coronary artery bypass grafting.

LENUS (Irish Health Repository)

Flynn, Michael J

2012-02-03

OBJECTIVE: Vasoactive agents and inotropes influence conduit-coronary blood flow following coronary artery bypass grafting (CABG). It was hypothesized that dopexamine hydrochloride, a dopamine A-1 (DA-1) and beta(2) agonist would increase conduit-coronary blood flow. A prospective randomized double blind clinical trial was carried out to test this hypothesis. DA-1 receptors have previously been localized to human left ventricle. METHODS: Twenty-six American Society of Anaesthesiology class 2-3 elective coronary artery bypass graft patients who did not require inotropic support on separation from cardiopulmonary bypass (CPB) were studied. According to a randomized allocation patients received either dopexamine (1 microg\\/kg per min) or placebo (saline) by intravenous infusion for 15 min. Immediately prior to and at 5,10 and 15 min of infusion, blood flow through the internal mammary and vein grafts (Transit time flow probes, Transonic Ltd.), heart rate, cardiac index, mean arterial pressure and pulmonary haemodynamics were noted. The data were analysed using multivariate analysis of variance. RESULTS: Low-dose dopexamine (1 microg\\/kg per min) caused a significant increase in mammary graft blood flow compared to placebo at 15 min of infusion (P=0.028, dopexamine group left internal mammary artery (LIMA) flow of 43.3+\\/-14.2 ml\\/min, placebo group LIMA flow at 26.1+\\/-16.3 ml\\/min). Dopexamine recipients demonstrated a non-significant trend to increased saphenous vein graft flow (P=0.059). Increased heart rate was the only haemodynamic change induced by dopexamine (P=0.004, dopexamine group at 85.2+\\/-9.6 beats\\/min and placebo group at 71.1+\\/-7.6 beats\\/min after 15 min of infusion). CONCLUSION: This study demonstrates that administration of dopexamine (1 microg\\/kg per min) was associated with a significant increase in internal mammary artery graft blood flow with mild increase in heart rate being the only haemodynamic change. Low-dose dopexamine may

Dynamics of blood flow and thrombus formation in a multi-bypass microfluidic ladder network.

Science.gov (United States)

Zilberman-Rudenko, Jevgenia; Sylman, Joanna L; Lakshmanan, Hari H S; McCarty, Owen J T; Maddala, Jeevan

2017-02-01

The reaction dynamics of a complex mixture of cells and proteins, such as blood, in branched circulatory networks within the human microvasculature or extravascular therapeutic devices such as extracorporeal oxygenation machine (ECMO) remains ill-defined. In this report we utilize a multi-bypass microfluidics ladder network design with dimensions mimicking venules to study patterns of blood platelet aggregation and fibrin formation under complex shear. Complex blood fluid dynamics within multi-bypass networks under flow were modeled using COMSOL. Red blood cells and platelets were assumed to be non-interacting spherical particles transported by the bulk fluid flow, and convection of the activated coagulation factor II, thrombin, was assumed to be governed by mass transfer. This model served as the basis for predicting formation of local shear rate gradients, stagnation points and recirculation zones as dictated by the bypass geometry. Based on the insights from these models, we were able to predict the patterns of blood clot formation at specific locations in the device. Our experimental data was then used to adjust the model to account for the dynamical presence of thrombus formation in the biorheology of blood flow. The model predictions were then compared to results from experiments using recalcified whole human blood. Microfluidic devices were coated with the extracellular matrix protein, fibrillar collagen, and the initiator of the extrinsic pathway of coagulation, tissue factor. Blood was perfused through the devices at a flow rate of 2 µL/min, translating to physiologically relevant initial shear rates of 300 and 700 s -1 for main channels and bypasses, respectively. Using fluorescent and light microscopy, we observed distinct flow and thrombus formation patterns near channel intersections at bypass points, within recirculation zones and at stagnation points. Findings from this proof-of-principle ladder network model suggest a specific correlation between

Differences in displayed pump flow compared to measured flow under varying conditions during simulated cardiopulmonary bypass.

LENUS (Irish Health Repository)

Hargrove, M

2008-07-01

Errors in blood flow delivery due to shunting have been reported to reduce flow by, potentially, up to 40-83% during cardiopulmonary bypass. The standard roller-pump measures revolutions per minute and a calibration factor for different tubing sizes calculates and displays flow accordingly. We compared displayed roller-pump flow with ultrasonically measured flow to ascertain if measured flow correlated with the heart-lung pump flow reading. Comparison of flows was measured under varying conditions of pump run duration, temperature, viscosity, varying arterial\\/venous loops, occlusiveness, outlet pressure, use of silicone or polyvinyl chloride (PVC) in the roller race, different tubing diameters, and use of a venous vacuum-drainage device.

Cerebral blood flow response to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in children

International Nuclear Information System (INIS)

Kern, F.H.; Ungerleider, R.M.; Quill, T.J.; Baldwin, B.; White, W.D.; Reves, J.G.; Greeley, W.J.

1991-01-01

We examined the relationship of changes in partial pressure of carbon dioxide on cerebral blood flow responsiveness in 20 pediatric patients undergoing hypothermic cardiopulmonary bypass. Cerebral blood flow was measured during steady-state hypothermic cardiopulmonary bypass with the use of xenon 133 clearance methodology at two different arterial carbon dioxide tensions. During these measurements there was no significant change in mean arterial pressure, nasopharyngeal temperature, pump flow rate, or hematocrit value. Cerebral blood flow was found to be significantly greater at higher arterial carbon dioxide tensions (p less than 0.01), so that for every millimeter of mercury rise in arterial carbon dioxide tension there was a 1.2 ml.100 gm-1.min-1 increase in cerebral blood flow. Two factors, deep hypothermia (18 degrees to 22 degrees C) and reduced age (less than 1 year), diminished the effect carbon dioxide had on cerebral blood flow responsiveness but did not eliminate it. We conclude that cerebral blood flow remains responsive to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in infants and children; that is, increasing arterial carbon dioxide tension will independently increase cerebral blood flow

Measurement of flow by-passing and turbulent mixing in a model of a fast-reactor steam generator

International Nuclear Information System (INIS)

Little, A.J.; Fallows, T.; Central Electricity Generating Board, Leatherhead

1989-01-01

A description is given of measurements of edge by-pass velocities and turbulent mixing in a model of a fast reactor steam generator. The velocity measurements were carried out using a DANTEC triple-split fibre probe which allowed both the speed and flow angle of a velocity vector to be measured in a plane normal to the axis of the probe. The measurements revealed the presence of reverse flows in the by-pass and adjacent in-bank channels downstream of a grid plate. The magnitude of the by-pass flow was reduced considerably by the insertion of a kicker grid at the mid point between grid plates. Turbulent mixing measurements revealed that circumferential mixing in channels near the by-pass channel was up to 5 times greater than the radial mixing. The level of radial mixing at the edge of the bank was similar to that measured near the centre of the bank. A method of transposing mass diffusion measurements in air to thermal diffusivities of sodium is discussed. (orig.)

Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

Science.gov (United States)

Mulligan, Kevin; Towler, Brett; Haro, Alexander J.; Ahlfeld, David P.

2017-01-01

Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity to the sweeping velocity magnitude changes along the full length and depth of a guide wall under a wide range of bypass flow percentages within a power canal. This paper focused on two guide wall configurations, each set at an angle of 45 ° to the approaching flow field and at a depth of 10 and 20 ft (3.05 and 6.10 m). The hydraulic conditions upstream of each guide wall configuration were shown to be impacted by a change in the bypass flow percentage, not only near the bypass but also at upstream sections of the guide wall. Furthermore, the effect of changing the bypass flow percentage was similar for both guide wall depths. In both cases, the effect of increasing the bypass flow percentage was magnified closer to the bypass and deeper in the water column along the guide wall.

Measurement of Blood Flow in an Intracranial Artery Bypass From the Internal Maxillary Artery by Intraoperative Duplex Sonography.

Science.gov (United States)

Yu, Zaitao; Shi, Xiang'en; Brohi, Shams Raza; Qian, Hai; Liu, Fangjun; Yang, Yang

2017-02-01

This study explored the hemodynamic characteristics of a subcranial-intracranial bypass from the internal maxillary artery by measuring blood flow on intraoperative duplex sonography. The hemodynamic parameters of the internal maxillary artery (n = 20), radial artery (n = 20), internal maxillary artery-middle cerebral artery bypass (n = 42), and internal maxillary artery-posterior cerebral artery bypass (n = 9) were measured by intraoperative duplex sonography. There was no significant difference in the internal diameters of the internal maxillary and radial arteries (mean ± SD, 2.51 ± 0.34 versus 2.56 ± 0.22 mm; P = .648). The mean radial artery graft length for subcranial-intracranial bypasses was 88.5 ± 12.78 mm (95% confidence interval [CI], 80.8-90.2 mm). Internal maxillary artery-middle cerebral artery bypasses required a shorter radial artery graft than internal maxillary artery-posterior cerebral artery bypasses (77.8 ± 2.47 versus 104.8 ± 4.77 mm; P = .001). The mean flow volumes were 85.3 ± 18.5 mL/min (95% CI, 76.6-93.9 mL/min) for the internal maxillary artery, 72.6 ± 26.4 mL/min (95% CI, 64.3-80.9 mL/min) for internal maxillary artery-middle cerebral artery bypasses, and 45.4 ± 6.7 mL/min (95% CI, 40.7-50.0 mL/min) for internal maxillary artery-posterior cerebral artery bypasses. All grafts were opened after the success of the salvage procedures had been established, and the early patency rates (1 month after the operation) were 95% for internal maxillary artery-middle cerebral artery bypasses and 100% the internal maxillary artery-posterior cerebral artery bypasses. Measurement of blood flow by intraoperative sonography can be helpful in decision making and predicting graft patency and success after neurosurgical bypass procedures. © 2016 by the American Institute of Ultrasound in Medicine.

Rankine cycle load limiting through use of a recuperator bypass

Science.gov (United States)

Ernst, Timothy C.

2011-08-16

A system for converting heat from an engine into work includes a boiler coupled to a heat source for transferring heat to a working fluid, a turbine that transforms the heat into work, a condenser that transforms the working fluid into liquid, a recuperator with one flow path that routes working fluid from the turbine to the condenser, and another flow path that routes liquid working fluid from the condenser to the boiler, the recuperator being configured to transfer heat to the liquid working fluid, and a bypass valve in parallel with the second flow path. The bypass valve is movable between a closed position, permitting flow through the second flow path and an opened position, under high engine load conditions, bypassing the second flow path.

An Experimental Design of Bypass Magneto-Rheological (MR) damper

Science.gov (United States)

Rashid, MM; Aziz, Mohammad Abdul; Raisuddin Khan, Md.

2017-11-01

The magnetorheological (MR) fluid bypass damper fluid flow through a bypass by utilizing an external channel which allows the controllability of MR fluid in the channel. The Bypass MR damper (BMRD) contains a rectangular bypass flow channel, current controlled movable piston shaft arrangement and MR fluid. The static piston coil case is winding by a coil which is used inside the piston head arrangement. The current controlled coil case provides a magnetic flux through the BMRD cylinder for controllability. The high strength of alloy steel materials are used for making piston shaft which allows magnetic flux propagation throughout the BMRD cylinder. Using the above design materials, a Bypass MR damper is designed and tested. An excitation of current is applied during the experiment which characterizes the BMRD controllability. It is shown that the BMRD with external flow channel allows a high controllable damping force using an excitation current. The experimental result of damping force-displacement characteristics with current excitation and without current excitation are compared in this research. The BMRD model is validated by the experimental result at various frequencies and applied excitation current.

Aluminum-contaminant transport by surface runoff and bypass flow from an acid sulphate soil

NARCIS (Netherlands)

Minh, L.Q.; Tuong, T.P.; Mensvoort, van M.E.F.; Bouma, J.

2002-01-01

Quantifying the process and the amount of acid-contaminant released to the surroundings is important in assessing the environmental hazards associated with reclaiming acid sulphate soils (ASS). The roles of surface runoff and bypass flow (i.e. the rapid downward flow of free water along macropores

Variable volume combustor with an air bypass system

Science.gov (United States)

Johnson, Thomas Edward; Ziminsky, Willy Steve; Ostebee, Heath Michael; Keener, Christopher Paul

2017-02-07

The present application provides a combustor for use with flow of fuel and a flow of air in a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles positioned within a liner and an air bypass system position about the liner. The air bypass system variably allows a bypass portion of the flow of air to bypass the micro-mixer fuel nozzles.

Effects of cardiopulmonary bypass on cerebral blood flow in neonates, infants, and children

International Nuclear Information System (INIS)

Greeley, W.J.; Ungerleider, R.M.; Kern, F.H.; Brusino, F.G.; Smith, L.R.; Reves, J.G.

1989-01-01

Cardiopulmonary bypass (CPB) management in neonates, infants, and children requires extensive alterations in temperature, pump flow rate, and perfusion pressure, with occasional periods of circulatory arrest. The effect of these alterations on cerebral blood flow (CBF) are unknown. This study was designed to determine the relation of temperature and mean arterial pressure to CBF during hypothermic CPB (18-32 degrees C), with and without periods of total circulatory arrest. CBF was measured before, during, and after hypothermic CPB with xenon-clearance techniques in 67 pediatric patients, aged 1 day-16 years. Patients were grouped based on different CPB techniques: group A, repair during moderate-hypothermic bypass at 25-32 degrees C; group B, repair during deep-hypothermic bypass at 18-22 degrees C; and group C, repair with total circulatory arrest at 18 degrees C. There was a significant correlation of CBF with temperature during CPB. CBF significantly decreased under hypothermic conditions in all groups compared with prebypass levels under normothermia. In groups A and B, CBF returned to baseline levels in the rewarming phase of CPB and exceeded baseline levels after bypass. In group C, no significant increase in CBF was observed during rewarming after total circulatory arrest (32 ± 12 minutes) or after weaning from CPB. During moderate-hypothermic CPB (25-32 degrees C), there was no association between CBF and mean arterial pressure. However, during deep-hypothermic CPB (18-22 degrees C), there was a association between CBF and mean arterial pressure

Experimental and Numerical Evaluation of the By-Pass Flow in a Catalytic Plate Reactor for Hydrogen Production

DEFF Research Database (Denmark)

Sigurdsson, Haftor Örn; Kær, Søren Knudsen

2011-01-01

Numerical and experimental study is performed to evaluate the reactant by-pass flow in a catalytic plate reactor with a coated wire mesh catalyst for steam reforming of methane for hydrogen generation. By-pass of unconverted methane is evaluated under different wire mesh catalyst width to reactor...

Brain microvascular function during cardiopulmonary bypass

International Nuclear Information System (INIS)

Sorensen, H.R.; Husum, B.; Waaben, J.; Andersen, K.; Andersen, L.I.; Gefke, K.; Kaarsen, A.L.; Gjedde, A.

1987-01-01

Emboli in the brain microvasculature may inhibit brain activity during cardiopulmonary bypass. Such hypothetical blockade, if confirmed, may be responsible for the reduction of cerebral metabolic rate for glucose observed in animals subjected to cardiopulmonary bypass. In previous studies of cerebral blood flow during bypass, brain microcirculation was not evaluated. In the present study in animals (pigs), reduction of the number of perfused capillaries was estimated by measurements of the capillary diffusion capacity for hydrophilic tracers of low permeability. Capillary diffusion capacity, cerebral blood flow, and cerebral metabolic rate for glucose were measured simultaneously by the integral method, different tracers being used with different circulation times. In eight animals subjected to normothermic cardiopulmonary bypass, and seven subjected to hypothermic bypass, cerebral blood flow, cerebral metabolic rate for glucose, and capillary diffusion capacity decreased significantly: cerebral blood flow from 63 to 43 ml/100 gm/min in normothermia and to 34 ml/100 gm/min in hypothermia and cerebral metabolic rate for glucose from 43.0 to 23.0 mumol/100 gm/min in normothermia and to 14.1 mumol/100 gm/min in hypothermia. The capillary diffusion capacity declined markedly from 0.15 to 0.03 ml/100 gm/min in normothermia but only to 0.08 ml/100 gm/min in hypothermia. We conclude that the decrease of cerebral metabolic rate for glucose during normothermic cardiopulmonary bypass is caused by interruption of blood flow through a part of the capillary bed, possibly by microemboli, and that cerebral blood flow is an inadequate indicator of capillary blood flow. Further studies must clarify why normal microvascular function appears to be preserved during hypothermic cardiopulmonary bypass

Determination of pump flow rate during cardiopulmonary bypass in obese patients avoiding hemodilution.

Science.gov (United States)

Santambrogio, Luisa; Leva, Cristian; Musazzi, Giorgio; Bruno, Piergiorgio; Vailati, Andrea; Zecchillo, Franco; Di Credico, Germano

2009-01-01

During cardiopulmonary bypass the pump flow is usually set on 2.4 L/min/m(2) of body surface area (BSA) to guarantee adequate tissue perfusion without differences for patient constitutional type. The present study attempts to evaluate the adequacy of pump flow rate in obese patients, considering the ideal weight instead of the real one, avoiding the overflow side effects and hemodilution. Obese patients with body mass index (BMI) > 30 presented for cardiac surgery were randomized in two groups: in one the cardiopulmonary bypass was led traditionally, in the other, pump flow rate was calculated on ideal BMI of 25. Demographics, preoperative tests, and monitoring data were registered. Mortality at hospital discharge and 30 days after were analyzed. The pump flow rate between the groups was different (4.46 vs. 4.87; p = 0.004); there were no differences in organ perfusion (SvO(2); diuresis) and mortality, but the study group presented fewer complications and blood transfusions. The BSA is widely used as the biometric unit to normalize physiologic parameters included pump flow rate, but it is disputable if this practice is correct also in obese patients. The study group, in which pump flow rate was set on ideal BSA, presented no difference in diuresis and mixed venous saturation but fewer complications and fewer perioperative blood transfusions.

Prediction of coronary artery bypass graft flow

International Nuclear Information System (INIS)

Tamiya, Eiji; Hada, Yoshiyuki; Asano, Ken-ichi; Iio, Masahiro.

1991-01-01

To predict the coronary artery bypass graft (CABG) flow based on the time density curve (TDC) obtained from the digital subtraction aortograms (DSA), we developed a pulsatile CABG model (perfusion pressure 60,130 mmHg, pulse rate 53,126/min, cardiac output 3-7 l/min, diameter of the graft 2.1∼6.0 mm). After positioning the regions of interest (ROI), we injected contrast medium(5∼40 ml/sec, 5∼40 ml) into the outlet conduit. Concerning the TDCs, we calculated appearance time (Ta), peak densities (Dp), peak time (Tp), disappearance time (Td), integral of TDC, ΔTp (difference of Tp between two ROI) and ΔTa (difference of Ta between two ROI). Perfusion pressure, graft flow and output curve were similar to those of patients with CABG. Ta, Tp, Td, and ΔTp were affected by both the injection rate and the volume of the contrast medium; while Dp and the TDC integral were only affected by the latter parameter. Under the same conditions of contrast medium injection, the TDC depended strongly on graft flow, diameter of the graft, output and pulse rate. 21.6+0.92π·d 2 /4·Δ1/ΔTp·60 provided the most accurate estimation of CABG flow (r=0.865, p<0.01). We conclude that densitometric analysis of DSA may be useful in the prediction of CABG flow. (author)

In vitro flow investigations in the aortic arch during cardiopulmonary bypass with stereo-PIV.

Science.gov (United States)

Büsen, Martin; Kaufmann, Tim A S; Neidlin, Michael; Steinseifer, Ulrich; Sonntag, Simon J

2015-07-16

The cardiopulmonary bypass is related to complications like stroke or hypoxia. The cannula jet is suspected to be one reason for these complications, due to the sandblast effect on the vessel wall. Several in silico and in vitro studies investigated the underlying mechanisms, but the applied experimental flow measurement techniques were not able to address the highly three-dimensional flow character with a satisfying resolution. In this work in vitro flow measurements in a cannulated and a non-cannulated aortic silicone model are presented. Stereo particle image velocimetry measurements in multiple planes were carried out. By assembling the data of the different measurement planes, quasi 3D velocity fields with a resolution of~1.5×1.5×2.5 mm(3) were obtained. The resulting velocity fields have been compared regarding magnitude, streamlines and vorticity. The presented method shows to be a suitable in vitro technique to measure and address the three-dimensional aortic CPB cannula flow with a high temporal and spatial resolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coronary artery bypass grafting without cardiopulmonary bypass and without interruption of native coronary flow using a novel anastomosis site restraining device ("Octopus").

Science.gov (United States)

Borst, C; Jansen, E W; Tulleken, C A; Gründeman, P F; Mansvelt Beck, H J; van Dongen, J W; Hodde, K C; Bredée, J J

1996-05-01

This study assessed the feasibility of coronary artery bypass grafting on the beating heart without interruption of native coronary blood flow using a novel anastomosis site restraining device. Recently, an end-to-side bypass technique was described that does not require interruption of flow in the recipient artery. By means of a suction device ("Octopus"), in 31 pigs the epicardium was grasped and immobilized through an arm contraption fixed to the operating table. In the first 15 consecutive pigs (study I), the two-dimensional motion of an epicardial beacon was monitored. In 16 subsequent pigs (study II), an internal mammary artery was grafted under the microscope in two steps to a proximal coronary artery segment, without cardiopulmonary bypass. First, the internal mammary artery was sutured end-to-side to the outside of the coronary artery. Secondly, an orifice was punched in the partitioning coronary wall by an excimer laser catheter introduced through a temporary side-branch of the internal mammary artery. Study II: During 43 suction periods in four anastomosis areas, immobilization was achieved for 15 to 169 min (>30 h in total) in 13 open- and 9 closed-chest procedures without hemodynamic deterioration. The area circumscribed by the edges of the beacon trajectory (area in which the anastomosis is to be tracked) was reduced from 73.0 +/- 43.0 mm(2) (mean +/- SD) to 1.3 +/- 0.5 mm(2) (p<0.001) in the open-chest and to 0.2 +/- 0.2 mm(2) in the closed-chest procedure. At 6 weeks, no myocardial or coronary suction lesions were found. Study II: Nonocclusive anastomosis surgery required 25 +/- 3 min. No leakage, serious arrhythmias, graft closure or hemodynamic deterioration occurred during the procedure or for 2 h after ligating the coronary artery proximally. At 6 weeks, all seven grafts were patent. Coronary bypass on the beating heart without interruption of coronary flow is feasible. In both open- and in closed-chest procedures, the "Octopus" reduced

Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?

DEFF Research Database (Denmark)

Thomassen, Sisse Anette; Larsson, A; Andreasen, Jan Jesper

Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today's cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior...

Distinct alterations in sublingual microcirculatory blood flow and hemoglobin oxygenation in on-pump and off-pump coronary artery bypass graft surgery

NARCIS (Netherlands)

Atasever, Bektaş; Boer, Christa; Goedhart, Peter; Biervliet, Jules; Seyffert, Jan; Speekenbrink, Ron; Schwarte, Lothar; de Mol, Bas; Ince, Can

2011-01-01

The authors hypothesized that cardiopulmonary bypass (CPB) (on-pump) is associated with more severe changes in the microcirculatory blood flow and tissue oxygenation as compared with off-pump coronary artery bypass surgery. An observational study. A university hospital and teaching hospital.

Economic consequences of extra by-passes in district heating networks. Investment-, running- and maintenance costs

International Nuclear Information System (INIS)

Herbert, P.

1995-02-01

For various reasons, extra by-passes are installed in district heating networks to ensure a high flow temperature when the water circulation is insufficient. By 'extra by-pass' we here mean a connection between the distribution pipe and the return pipe. This study mainly deals with extra by-passes to prevent freezing. The estimation of the extra by-pass costs is based on the district heating rates. Our assumption is that an extra by-pass can be regarded as a substation in the district heating network, with regard to the demand for the water flow, heat and power. The reason is the difficulty to obtain available facts to estimate the real costs concerning extra by-passes. Therefore, the method can not claim that the information about the costs is exact but gives an indication of the size of them. The valves in an extra by-pass can be set more or less open. We assume that manual valves in extra by-passes are wide open. Thermostatic valves are, however, assumed to be adjusted in order to cause a very small water flow. 2 refs, 16 figs, 9 tabs, 6 appendices

Integrated turbine bypass system

Energy Technology Data Exchange (ETDEWEB)

Johnson, L.H.; Dickenson, R.J.; Parry, W.T.; Retzlaff, K.M.

1982-07-01

Turbine steam-flow bypasses have been used for years in various sizes and applications. Because of differing system requirements, their use has been more predominant in Europe than in the United States. Recently, some utilities and consulting engineers have been re-evaluating their need for various types of bypass operation in fossil-fuelled power plants.

By-pass flows and temperature distribution in a hot gas duct internally insulated by carbon stone

International Nuclear Information System (INIS)

Konuk, A.A.

1979-01-01

A mathematical model has been developed to calculate by-pass flows and temperature distribution in a hot gas duct internally insulated by carbon stone rings. The equations of conservation of mass and momentum are solved for a piping system to obtain axial and radial by-pass velocities. The energy equation is solved next by a marching method to obtain the radial temperature distribution along the duct. The results, although qualitative due to simplifications in the model, are useful to study the effects of duct geometry on its performance. (Author) [pt

No major differences in 30-day outcomes in high-risk patients randomized to off-pump versus on-pump coronary bypass surgery: the best bypass surgery trial

DEFF Research Database (Denmark)

Møller, Christian H; Perko, Mario J; Lund, Jens T

2010-01-01

Off-pump coronary artery bypass grafting compared with coronary revascularization with cardiopulmonary bypass seems safe and results in about the same outcome in low-risk patients. Observational studies indicate that off-pump surgery may provide more benefit in high-risk patients. Our objective...... was to compare 30-day outcomes in high-risk patients randomized to coronary artery bypass grafting without or with cardiopulmonary bypass....

Intra-arterial papaverine and leg vascular resistance during in situ bypass surgery with high or low epidural anaesthesia

DEFF Research Database (Denmark)

Rørdam, Peter; Jensen, Leif Panduro; Schroeder, T V

1993-01-01

In situ saphenous vein arterial bypass flow was studied in 16 patients with respect to level of epidural anaesthesia. Arterial pressure and electromagnetic flow were used to evaluate arterial tone by intra-arterial (i.a.) papaverine. Eight patients had a low epidural block (... patients were operated during high epidural anaesthesia (> Th. 10). Flow increased and arterial pressure decreased after i.a. papaverine in all patients. When compared with patients operated during high epidural anaesthesia, flow increase and decrease in vascular resistance took place in patients operated...... during low epidural anaesthesia (P i.a. papaverine was not significantly different in patients operated in low epidural and general anaesthesia (n = 8). In eight patients with insulin-dependent diabetes mellitus who had low epidural anaesthesia, the increase...

Cerebral autoregulation and flow/metabolism coupling during cardiopulmonary bypass: the influence of PaCO2

International Nuclear Information System (INIS)

Murkin, J.M.; Farrar, J.K.; Tweed, W.A.; McKenzie, F.N.; Guiraudon, G.

1987-01-01

Measurement of 133 Xe clearance and effluent cerebral venous blood sampling were used in 38 patients to determine the effects of cardiopulmonary bypass, and of maintaining temperature corrected or noncorrected PaCO 2 at 40 mm Hg on regulation of cerebral blood flow (CBF) and flow/metabolism coupling. After induction of anesthesia with diazepam and fentanyl, mean CBF was 25 ml X 100 g-1 X min-1 and cerebral oxygen consumption, 1.67 ml X 100 g-1 X min-1. Cerebral oxygen consumption during nonpulsatile cardiopulmonary bypass at 26 degrees C was reduced to 0.42 ml X 100 g-1 X min-1 in both groups. CBF was reduced to 14-15 ml X 100 g-1 X min-1 in the non-temperature-corrected group (n = 21), was independent of cerebral perfusion pressure over the range of 20-100 mm Hg, but correlated with cerebral oxygen consumption. In the temperature-corrected group (n = 17), CBF varied from 22 to 32 ml X 100 g-1 X min-1, and flow/metabolism coupling was not maintained (i.e., CBF and cerebral oxygen consumption varied independently). However, variation in CBF correlated significantly with cerebral perfusion pressure over the pressure range of 15-95 mm Hg. This study demonstrates a profound reduction in cerebral oxygen consumption during hypothermic nonpulsatile cardiopulmonary bypass. When a non-temperature-corrected PaCO 2 of approximately 40 mm Hg was maintained, CBF was lower, and analysis of pooled data suggested that CBF regulation was better preserved, i.e., CBF was independent of pressure changes and dependent upon cerebral oxygen consumption

Coronary flow and reactivity, but not arrhythmia vulnerability, are affected by cardioplegia during cardiopulmonary bypass in piglets

DEFF Research Database (Denmark)

Liuba, Petru; Johansson, Sune; Pesonen, Erkki

2013-01-01

Background: Surgery under cardiopulmonary bypass (CPB) is still associated with significant cardiovascular morbidity in both pediatric and adult patients but the mechanisms are not fully understood. Abnormalities in coronary flow and function have been suggested to play an important role. Prior...

The Application of Advanced Technique of Fan Frame Unit on High Bypass Ratio Aero Engine

Directory of Open Access Journals (Sweden)

Hou Peng

2017-01-01

Full Text Available High bypass ratio aero-engine was widely used on military and civil aviation domain, as the power of larger aircraft. Fan frame unit was the main bearing frame of high bypass ratio aero-engine, which composed of strut, HUB MID BOX and external bypass parts. Resin/composite was used on external bypass parts(acoustic liner, containment ring, fan outlet guide vane and fan case skin fillets, which not only reduced the weight and manufacturing cost, but also improved the noise absorption, containment and anti-fatigue ability of engine. The design of composite was becoming a key technique for high bypass ratio aero-engine. In special test of the core engine, nitrogen cooling system was designed to cool the cavity of spool. The nitrogen pipeline passed through the inner cavity of fan frame, then inserted into NO. 3 bearing seal, so nitrogen gas was sent into the cavity of core engine spool. On high bypass ratio aero-engine, the external bypass and fan frame inner cavity were the design platform for advanced technique, such as composite and pipeline system, and also provided guarantee for reliable operation of engine.

Assessment of some interfacial shear correlations in a model of ECC bypass flow in PWR reactor downcomer

International Nuclear Information System (INIS)

Popov, N.K.; Rohatgi, U.S.

1987-01-01

The bypass/refill process in the PWR reactor downcomer, following a large rupture of a cold leg coolant supply pipe, is a complicated thermo-hydraulic two-phase flow phenomenon. Mathematical modeling of such phenomena is always accompanied with a difficult task of selection of suitable constitutive correlations. In a typically hydrodynamic phenomenon, like ECC refill process of the reactor lower plenum is considered, the phasic interfacial friction is the most influential constitutive correlation. Therefore, assessment of the well-known widely-used interfacial friction constitutive correlations in the model of ECC bypass/refill process, is the subject of this paper

Evaluation of the patency of an extracranial-intracranial bypass using magnetic resonance angiography with selective presaturation of bypass vessels

Energy Technology Data Exchange (ETDEWEB)

Mabuchi, Shoji; Nakayama, Naoki; Isu, Toyohiko; Harata, Tatsuo; Nanbu, Toshikazu [Kushiro Rousai Hospital, Hokkaido (Japan)

1994-06-01

Three-dimensional time-of-flight magnetic resonance (MR) angiography using radiofrequency presaturation pulses was used to evaluate the patency of extracranial-intracranial (EC/IC) bypass in 11 patients. Presaturation causes signal loss in the vascular territory supplied by the presaturated EC/IC bypass graft. In all patients with a patent EC/IC bypass graft confirmed on conventional angiography, disappearance of the signal of the middle cerebral artery receiving blood flow from the bypass graft was clearly observed on MR angiograms with presaturation, indicating patency of the EC/IC bypass graft. MR angiography with presaturation pulses is a noninvasive and repeatable method for evaluation of the function of an EC/IC bypass graft. (author).

Cerebral autoregulation and flow/metabolism coupling during cardiopulmonary bypass: the influence of PaCO/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Murkin, J.M.; Farrar, J.K.; Tweed, W.A.; McKenzie, F.N.; Guiraudon, G.

1987-09-01

Measurement of /sup 133/Xe clearance and effluent cerebral venous blood sampling were used in 38 patients to determine the effects of cardiopulmonary bypass, and of maintaining temperature corrected or noncorrected PaCO/sub 2/ at 40 mm Hg on regulation of cerebral blood flow (CBF) and flow/metabolism coupling. After induction of anesthesia with diazepam and fentanyl, mean CBF was 25 ml X 100 g-1 X min-1 and cerebral oxygen consumption, 1.67 ml X 100 g-1 X min-1. Cerebral oxygen consumption during nonpulsatile cardiopulmonary bypass at 26 degrees C was reduced to 0.42 ml X 100 g-1 X min-1 in both groups. CBF was reduced to 14-15 ml X 100 g-1 X min-1 in the non-temperature-corrected group (n = 21), was independent of cerebral perfusion pressure over the range of 20-100 mm Hg, but correlated with cerebral oxygen consumption. In the temperature-corrected group (n = 17), CBF varied from 22 to 32 ml X 100 g-1 X min-1, and flow/metabolism coupling was not maintained (i.e., CBF and cerebral oxygen consumption varied independently). However, variation in CBF correlated significantly with cerebral perfusion pressure over the pressure range of 15-95 mm Hg. This study demonstrates a profound reduction in cerebral oxygen consumption during hypothermic nonpulsatile cardiopulmonary bypass. When a non-temperature-corrected PaCO/sub 2/ of approximately 40 mm Hg was maintained, CBF was lower, and analysis of pooled data suggested that CBF regulation was better preserved, i.e., CBF was independent of pressure changes and dependent upon cerebral oxygen consumption.

Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

Science.gov (United States)

Dyson, Rodger W (Inventor)

2015-01-01

A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

Fuel temperature prediction using a variable bypass gap size in the prismatic VHTR

International Nuclear Information System (INIS)

Lee, Sung Nam; Tak, Nam-il; Kim, Min Hwan

2016-01-01

Highlights: • The bypass flow of the prismatic very high temperature reactor is analyzed. • The bypass gap sizes are calculated considering the effect of the neutron fluences and thermal expansion. • The fuel hot spot temperature and temperature profiles are calculated using the variable gap size. • The BOC, MOC and EOC condition at the cycle 07 and 14 are applied. - Abstract: The temperature gradient and hot spot temperatures were calculated in the prismatic very high temperature reactor as a function of the variable bypass gap size. Many previous studies have predicted the temperature of the reactor core based on a fixed bypass gap size. The graphite matrix of the assemblies in the reactor core undergoes a dimensional change during the operation due to thermal expansion and neutron fluence. The expansion and shrinkage of the bypass gaps change the coolant flow fractions into the coolant channels, the control rod holes, and the bypass gaps. Therefore, the temperature of the assemblies may differ compared to those for the fixed bypass gap case. The temperature gradient and the hot spot temperatures are important for the design of reactor structures to ensure their safety and efficiency. In the present study, the temperature variation of the PMR200 is studied at the beginning (BOC), middle (MOC), and end (EOC) of cycles 07 and 14. CORONA code which has been developed in KAERI is applied to solve the thermal-hydraulics of the reactor core of the PMR200. CORONA solves a fluid region using a one-dimensional formulation and a solid region using a three-dimensional formulation to enhance the computational speed and still obtain a reasonable accuracy. The maximum temperatures in the fuel assemblies using the variable bypass gaps did not differ much from the corresponding temperatures using the fixed bypass gaps. However, the maximum temperatures in the reflector assemblies using the variable bypass gaps differ significantly from the corresponding temperatures

21 CFR 870.4300 - Cardiopulmonary bypass gas control unit.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass gas control unit. 870.4300... bypass gas control unit. (a) Identification. A cardiopulmonary bypass gas control unit is a device used to control and measure the flow of gas into the oxygenator. The device is calibrated for a specific...

Impact of top end anastomosis design on patency and flow stability in coronary artery bypass grafting.

Science.gov (United States)

Koyama, Sachi; Kitamura, Tadashi; Itatani, Keiichi; Yamamoto, Tadashi; Miyazaki, Shohei; Oka, Norihiko; Nakashima, Kouki; Horai, Tetsuya; Ono, Minoru; Miyaji, Kagami

2016-05-01

For coronary artery bypass grafting (CABG), free grafts such as a saphenous vein or radial artery are often used for grafts to the lateral and posterior walls. However, the relationship between top-end anastomosis design and long-term patency remains unknown. Because coronary artery blood flow is dominant during diastole, top-end anastomosis may work better if the graft is directed towards the apex, whereas the shortest graft pathway appears to be most efficient. Using computational fluid dynamic models, we evaluated the hemodynamic variables that were affected by the angle of the top-end anastomosis. We created three-dimensional geometries of the aortic root with coronary arteries that involved 75 % stenosis in the obtuse marginal and postero-lateral branches. Two bypass models under vasodilator administration were created: in a"Model A", the top-end anastomosis is parallel to the long axis of the ascending aorta and the graft passed over the conus directed towards the apex; in a "Model B", the top-end anastomosis is directed toward the shortest pathway, and form near the right angles to the long axis of the ascending aorta. Wall shear stress (WSS) and its fluctuation, an oscillatory shear index (OSI) were evaluated to predict fibrosis progression at the anastomosis site and graft flow. Graft flow was 197.3 ml/min and 207.3 ml/min in the "Model A" and "Model B", respectively. The minimal WSS value inside the graft with the "Model A" and "Model B" was 0.53 Pa and 4.09 Pa, respectively, and the OSI value was 0.46 and 0.04, respectively. The top-end anastomosis of a free graft should be directed vertically towards the aorta to achieve the shortest graft pathway to maintain a high graft flow rate and to avoid the risks of endothelial fibrosis and plaque progression over the long-term after CABG.

Direct ECC bypass phenomena in the MIDAS test facility during LBLOCA reflood phase

International Nuclear Information System (INIS)

Yun, B. J.; Kweon, T. S.; Ah, D. J.; Ju, I. C.; Song, C. H.; Park, J. K.

2001-01-01

This paper describes the experimental results of ECC Direct Bypass Phenomena in the downcomer during the late reflood phase of LBLOCA of the reactor that adopts Direct Vessel Injection as a ECC system. The experiments have been performed in MIDAS test facility using superheated steam and water. The test condition was determined, based on the preliminary analysis of TRAC code, from modified linear scaling method of 1/4.93 length scale. To measure the direct bypass fraction according to the nozzle location, separate effect tests have been performed in case of DVI-4(farthest from broken cold leg) injection, DVI-2(closest to broken cold leg) injection, and DVI-2 and 4 injection, respectively. Also the test was carried out varying the steam flow rate greatly to investigate the effect of steam flow rate on the direct bypass fraction of ECC water. Test results show that the direct bypass fraction of ECC water depends significantly on the injected steam mass flow rate. DVI-4 tests show that the direct bypass fraction increases drastically as the steam flow rate increases. However, in DVI-2 test most of the injected ECC water penetrates into lower downcomer. The direct bypass characteristic in each of DVI-2 and DVI-4 tests is reflected into the direct bypass characteristic curve of DVI-2 and 4 test. The steam condensation reaches to the theoretically allowable maximum value

Passage of downstream migrant American eels through an airlift-assisted deep bypass

Science.gov (United States)

Haro, Alexander J.; Watten, Barnaby J.; Noreika, John

2016-01-01

Traditional downstream guidance and bypass facilities for anadromous fishes (i.e., surface bypasses, surface guidance structures, and behavioral barriers) have frequently been ineffective for anguillid eels. Because eels typically spend the majority of their time near the bottom in the vicinity of intake structures, deep bypass structures with entrances near the bottom hold promise for increased effectiveness, thereby aiding in the recovery of this important species. A new design of a deep bypass system that uses airlift technology (the Conte Airlift Bypass) to induce flow in a bypass pipe was tested in a simulated intake entrance environment under controlled laboratory conditions. Water velocities of 0.9–1.5 m s−1 could be generated at the bypass entrance (opening with 0.073 m2 area), with corresponding flows through the bypass pipe of 0.07–0.11 m3 s−1. Gas saturation and hydrostatic pressure within the bypass pipe did not vary appreciably from a control (no air) condition under tested airflows. Migratory silver-phase American eels (Anguilla rostrata) tested during dark conditions readily located, entered, and passed through the bypass; initial avoidance rates (eels approaching but not entering the bypass entrance) were lower at higher entrance velocities. Eels that investigated the bypass pipe entrance tended to enter headfirst, but those that then exited the pipe upstream did so more frequently at lower entrance velocities. Eels appeared to swim against the flow while being transported downstream through the pipe; median transit times through the bypass for each test velocity ranged from 5.8 to 12.2 s, with transit time decreasing with increasing entrance velocity. Eels did not show strong avoidance of the vertical section of the pipe which contained injected air. No mortality or injury of bypassed eels was observed, and individual eels repeatedly passed through the bypass at rates of up to 40 passes per hour, suggesting that individuals do not

Occurrence of Pesticides in Water, Sediment, and Soil from the Yolo Bypass, California

Directory of Open Access Journals (Sweden)

Kelly L. Smalling

2007-02-01

Full Text Available The objective of this study was to evaluate the potential sources of pesticides to the Yolo Bypass, including those that could potentially impact critical life stages of resident fish. To assess direct inputs during inundation, pesticide concentrations were analyzed in water and suspended and bed sediment samples collected from source watersheds during high-flow events. To understand inputs from direct application on fields, pesticides were also measured in soils collected from several sites within the Bypass. Thirteen current-use pesticides were detected in water samples collected in 2004 with the highest pesticide concentrations observed at the input sites to the Bypass during high-flow. Hexazinone and simazine were detected at all sites and at some of the highest concentrations. In bed and suspended sediments collected in 2004 and 2005, thirteen current-use pesticides were detected along with DDT and its metabolites. Trifluralin, DDE, and DDT were highest in the bed sediments, whereas oxyfluorfen and thiobencarb were highest in the suspended sediments. With the exception of the three organochlorine insecticides, suspended sediments had higher pesticide concentrations compared to bed sediments, indicating the potential for pesticide transport especially during high-flow events. Soil samples were dominated by DDT and its degradates but also contained a variety of current-use pesticides typically at lower concentrations. The types of pesticides detected in water and sediments were correlated with agricultural application in each watershed. Understanding the distribution of pesticides between the water and sediment is important in assessing their fate and transport within the Bypass, and in evaluating the exposure and potential effects to resident fish.

Characterization of micro-invasive trabecular bypass stents by ex vivo perfusion and computational flow modeling

Directory of Open Access Journals (Sweden)

Hunter KS

2014-03-01

Full Text Available Kendall S Hunter,1 Todd Fjield,2 Hal Heitzmann,2 Robin Shandas,1 Malik Y Kahook3 1Department of Bioengineering, University of Colorado Denver, Aurora, CO, USA; 2Glaukos Corporation, Laguna Hills, CA, USA; 3University of Colorado Hospital Eye Center, Aurora, CO, USA Abstract: Micro-invasive glaucoma surgery with the Glaukos iStent® or iStent inject® (Glaukos Corporation, Laguna Hills, CA, USA is intended to create a bypass through the trabecular meshwork to Schlemm's canal to improve aqueous outflow through the natural physiologic pathway. While the iStent devices have been evaluated in ex vivo anterior segment models, they have not previously been evaluated in whole eye perfusion models nor characterized by computational fluid dynamics. Intraocular pressure (IOP reduction with the iStent was evaluated in an ex vivo whole human eye perfusion model. Numerical modeling, including computational fluid dynamics, was used to evaluate the flow through the stents over physiologically relevant boundary conditions. In the ex vivo model, a single iStent reduced IOP by 6.0 mmHg from baseline, and addition of a second iStent further lowered IOP by 2.9 mmHg, for a total IOP reduction of 8.9 mmHg. Computational modeling showed that simulated flow through the iStent or iStent inject is smooth and laminar at physiological flow rates. Each stent was computed to have a negligible flow resistance consistent with an expected significant decrease in IOP. The present perfusion results agree with prior clinical and laboratory studies to show that both iStent and iStent inject therapies are potentially titratable, providing clinicians with the opportunity to achieve lower target IOPs by implanting additional stents. Keywords: glaucoma, iStent, trabecular bypass, intraocular pressure, ab-interno, CFD

Cerebral blood flow and metabolism during cardiopulmonary bypass with special reference to effects of hypotension induced by prostacyclin

International Nuclear Information System (INIS)

Feddersen, K.; Aren, C.; Nilsson, N.J.; Radegran, K.

1986-01-01

Cerebral blood flow and metabolism of oxygen, glucose, and lactate were studied in 43 patients undergoing aortocoronary bypass. Twenty-five patients received prostacyclin infusion, 50 ng per kilogram of body weight per minute, during cardiopulmonary bypass (CPB), and 18 patients served as a control group. Regional cerebral blood flow (CBF) was studied by intraarterially injected xenon 133 and a single scintillation detector. Oxygen tension, carbon dioxide tension, oxygen saturation, glucose, and lactate were measured in arterial and cerebral venous blood. Mean arterial blood pressure decreased during hypothermia and prostacyclin infusion to less than 30 mm Hg. The regional CBF was, on average, 22 (standard deviation [SD] 4) ml/100 gm/min before CPB. It increased in the control group during hypothermia to 34 (SD 12) ml/100 gm/min, but decreased in the prostacyclin group to 15 (SD 5) ml/100 gm/min. It increased during rewarming in the prostacyclin group. After CPB, regional CBF was about 40 ml/100 gm/min in both groups. The cerebral arteriovenous oxygen pressure difference decreased more in the control group than in the prostacyclin group during hypothermia. The cerebral metabolic rate of oxygen decreased in both groups from approximately 2 ml/100 gm/min to about 1 ml/100 gm/min during hypothermia, increased again during rewarming, and after CPB was at the levels measured before bypass in both groups. There was no difference between the groups in regard to glucose and lactate metabolism

Economic consequences of extra by-passes in district heating networks. Investment-, running- and maintenance costs; Rundgaangars ekonomiska betydelse foer fjaerrvaermenaeten. Investerings-, drift- och underhaallskostnader

Energy Technology Data Exchange (ETDEWEB)

Herbert, P. [AaF-Energikonsult Stockholm AB, (Sweden)

1995-02-01

For various reasons, extra by-passes are installed in district heating networks to ensure a high flow temperature when the water circulation is insufficient. By `extra by-pass` we here mean a connection between the distribution pipe and the return pipe. This study mainly deals with extra by-passes to prevent freezing. The estimation of the extra by-pass costs is based on the district heating rates. Our assumption is that an extra by-pass can be regarded as a substation in the district heating network, with regard to the demand for the water flow, heat and power. The reason is the difficulty to obtain available facts to estimate the real costs concerning extra by-passes. Therefore, the method can not claim that the information about the costs is exact but gives an indication of the size of them. The valves in an extra by-pass can be set more or less open. We assume that manual valves in extra by-passes are wide open. Thermostatic valves are, however, assumed to be adjusted in order to cause a very small water flow. 2 refs, 16 figs, 9 tabs, 6 appendices

Rural health care bypass behavior: how community and spatial characteristics affect primary health care selection.

Science.gov (United States)

Sanders, Scott R; Erickson, Lance D; Call, Vaughn R A; McKnight, Matthew L; Hedges, Dawson W

2015-01-01

(1) To assess the prevalence of rural primary care physician (PCP) bypass, a behavior in which residents travel farther than necessary to obtain health care, (2) To examine the role of community and non-health-care-related characteristics on bypass behavior, and (3) To analyze spatial bypass patterns to determine which rural communities are most affected by bypass. Data came from the Montana Health Matters survey, which gathered self-reported information from Montana residents on their health care utilization, satisfaction with health care services, and community and demographic characteristics. Logistic regression and spatial analysis were used to examine the probability and spatial patterns of bypass. Overall, 39% of respondents bypass local health care. Similar to previous studies, dissatisfaction with local health care was found to increase the likelihood of bypass. Dissatisfaction with local shopping also increases the likelihood of bypass, while the number of friends in a community, and commonality with community reduce the likelihood of bypass. Other significant factors associated with bypass include age, income, health, and living in a highly rural community or one with high commuting flows. Our results suggest that outshopping theory, in which patients bundle services and shopping for added convenience, extends to primary health care selection. This implies that rural health care selection is multifaceted, and that in addition to perceived satisfaction with local health care, the quality of local shopping and levels of community attachment also influence bypass behavior. © 2014 National Rural Health Association.

The Best Bypass Surgery Trial

DEFF Research Database (Denmark)

Møller, Christian H; Jensen, Birte Østergaard; Gluud, Christian

2007-01-01

Recent trials suggest that off-pump coronary artery bypass grafting (OPCAB) reduces the risk of mortality and morbidity compared with conventional coronary artery bypass grafting (CCAB) using cardiopulmonary bypass. Patients with a moderate- to high-risk of complications after CCAB may have...

Cerebral blood flow measured by positron emission tomography during normothermic cardiopulmonary bypass: An experimental porcine study

DEFF Research Database (Denmark)

Thomassen, Sisse Anette; Kjaergaard, Benedict; Alstrup, Aage Kristian Olsen

2018-01-01

emission tomography (PET) using 15O-labelled water with no pharmacological interventions to maintain the MAP. Methods: Eight pigs (69-71 kg) were connected to normothermic CPB. After 60 minutes (min) with a CPB pump flow of 60 mL/kg/min, the pigs were changed to either 35 mL/kg/min or 47.5 mL/kg/min for 60......Background: Mean arterial blood pressure (MAP) and/or pump flow during normothermic cardiopulmonary bypass (CPB) are the most important factors of cerebral perfusion. The aim of this study was to explore the influence of CPB blood flow on cerebral blood flow (CBF) measured by dynamic positron...... min and, thereafter, all the pigs returned to 60 mL/kg/min for another 60 min. The MAP was measured continuously and the CBF was measured by positron emission tomography (PET) during spontaneous circulation and at each CPB pump flow after 30 min of steady state. Results: Two pigs were excluded due...

Development of a detailed core flow analysis code for prismatic fuel reactors

International Nuclear Information System (INIS)

Bennett, R.G.

1990-01-01

The development of a computer code for the analysis of the detailed flow of helium in prismatic fuel reactors is reported. The code, called BYPASS, solves, a finite difference control volume formulation of the compressible, steady state fluid flow in highly cross-connected flow paths typical of the Modular High-Temperature Gas Cooled Reactor (MHTGR). The discretization of the flow in a core region typically considers the main coolant flow paths, the bypass gap flow paths, and the crossflow connections between them. 16 refs., 5 figs

Numerical investigation and identification of susceptible sites of atherosclerotic lesion formation in a complete coronary artery bypass model.

Science.gov (United States)

Zhang, Jun-Mei; Chua, Leok Poh; Ghista, Dhanjoo N; Yu, Simon Ching Man; Tan, Yong Seng

2008-07-01

As hemodynamics is widely believed to correlate with anastomotic stenosis in coronary bypass surgery, this paper investigates the flow characteristics and distributions of the hemodynamic parameters (HPs) in a coronary bypass model (which includes both proximal and distal anastomoses), under physiological flow conditions. Disturbed flows (flow separation/reattachment, vertical and secondary flows) as well as regions of high oscillatory shear index (OSI) with low wall shear stress (WSS), i.e., high-OSI-and-low-WSS and low-OSI-and-high-WSS were found in the proximal and distal anastomoses, especially at the toe and heel regions of distal anastomosis, which indicate highly suspected sites for the onset of the atherosclerotic lesions. The flow patterns found in the graft and distal anastomoses of our model at deceleration phases are different from those of the isolated distal anastomosis model. In addition, a huge significant difference in segmental averages of HPs was found between the distal and proximal anastomoses. These findings further suggest that intimal hyperplasia would be more prone to form in the distal anastomosis than in the proximal anastomosis, particularly along the suture line at the toe and heel of distal anastomosis.

Improving the Sustainability of Transportation: Environmental and Functional Benefits of Right Turn By-Pass Lanes at Roundabouts

Directory of Open Access Journals (Sweden)

Marco Guerrieri

2015-05-01

Full Text Available The functional performances of conventional roundabouts (single-lane and multi-lane and innovative roundabouts (spiral, flower, C and turbo can be improved through right-turn bypass lanes controlled by stop, yield or free-flow signs. The article presents evaluations of the emissions of air pollutants (carbon dioxide, nitrogen oxides, particle pollution (PM10 and PM2.5, fuel consumption and construction, management, energetic and environmental costs in roundabouts without or with bypass lanes (controlled by stop, yield or free-flow. The suggested methodology has a general character and can be applied as a multi-parametric criterion for choosing road intersections, although, in the present paper, it has been employed only for a case study. For the aims of this research, we employed recent closed-form formulations to determine roundabout performances; moreover, we used the COPERT IV® software to estimate air emissions in nine different types of vehicles. Numerous traffic simulations were carried out. The variation in the maximum hourly traffic Qmax and annual traffic QTOT provided the appropriate domains of the examined geometric layouts, both in functional and environmental terms and with regard to generalized costs, estimated for a 10-year period. It resulted that the introduction of right-turn bypasses in all arms of conventional roundabouts with a one ring lane and one lane at the entries (single-lane roundabouts is the most cost-effective when the flows entering the roundabout are higher than Qmax = 2000 veh/h. Moreover, free-flow bypass lanes always provide greater capacity and lower delays than stop- or yield-signaled bypasses. However, with extremely high Qmax values, stop-controlled bypasses guarantee lower fuel consumption, while those with a yield sign lower total costs.

Interventions in Infrainguinal Bypass Grafts

International Nuclear Information System (INIS)

Mueller-Huelsbeck, S.; Order, B.-M.; Jahnke, T.

2006-01-01

The interventional radiologist plays an important role in the detection and prevention of infrainguinal bypass failure. Early detection and evaluation of flow-limiting lesions effectively preserve graft (venous bypass and polyester or expanded polytetrafluoroethylene bypass) patency by identifying stenoses before occlusion occurs. Delay in treatment of the at-risk graft may result in graft failure and a reduced chance of successful revascularization. For this reason, surveillance protocols form an important part of follow-up after infrainguinal bypass surgery. As well as having an understanding of the application of imaging techniques including ultrasound, MR angiography, CT angiography and digital subtraction angiography, the interventional radiologist should have detailed knowledge of the minimally invasive therapeutic options. Percutaneous transluminal angioplasty (PTA), or alternatively cutting balloon angioplasty, is the interventional treatment of choice in prevention of graft failure and occlusion. Further alternatives include metallic stent placement, fibrinolysis, and mechanical thrombectomy. Primary assisted patency rates following PTA can be up to 65% at 5 years. When the endovascular approach is unsuccessful, these therapeutic options are complemented by surgical procedures including vein patch revision, jump grafting, or placement of a new graft

Intraoperative echocardiographic imaging of coronary arteries and graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass.

Science.gov (United States)

Suematsu, Y; Takamoto, S; Ohtsuka, T

2001-12-01

No accepted approach exists for the intraoperative evaluation of the quality of coronary arteries and the technical adequacy of graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass. We assessed the accuracy of high-frequency epicardial echocardiography and power Doppler imaging in evaluating coronary arteries during coronary artery bypass grafting without cardiopulmonary bypass. To validate measurements of coronary arteries and graft anastomoses by high-frequency epicardial echocardiography and power Doppler imaging, we compared luminal diameters determined by these methods with diameters determined histologically in a study of off-pump coronary artery bypass grafting in 20 dogs. Technical errors were deliberately created in 10 grafts (stenosis group). The results of these animal validation studies showed that the maximum luminal diameters of coronary arteries and graft anastomoses measured by high-frequency epicardial echocardiography (HEE) and power Doppler imaging (PDI) correlated well with the histologic measurements: HEE = 1.027 x Histologic measurements + 0.005 (P anastomoses were examined intraoperatively by high-frequency epicardial echocardiography and power Doppler imaging, and luminal diameters determined by power Doppler imaging were compared with those determined by postoperative coronary angiography. The results demonstrated that graft anastomosis by power Doppler imaging correlated well with the angiographic measurements: PDI = 1.018 x Angiographic measurements - 0.106 (P anastomoses and can detect technical errors and inadequacies during coronary artery bypass grafting without cardiopulmonary bypass.

High-flow, low-head pumps provide safe passage for Pacific salmon

International Nuclear Information System (INIS)

Anon

2004-01-01

The installation of 29 ultra-low head, high capacity submersible pump and auxiliary equipment at the Rocky Reach Dam in Washington State to allow juvenile salmon safe passage on their journey down the Columbia River to the Pacific Ocean is described. The reputed cost of the project is US$160 million; its purpose is to get juvenile salmon safely around the Rocky Reach Dam without interfering with the dam's original mission of generating electric power. The project is the most expensive fish bypass on any Columbia River dam. Getting the salmon safely around the dam is intended to reduce the impact of hydroelectric power projects on the basin's salmon stocks which are now estimated at less than 10 per cent of their historic size, despite major hatchery programs. The Columbia River has the second largest volume flow of any river in the United States, and millions of people depend on it for employment in water-related industries, and for transportation. The new horizontally installed propeller pump was developed by ITT Flygt; it utilizes planetary gear reduced to match the motor speed with the propeller rpm. Each 90 kW propeller pump has a flow rate of seven cubic meters per second at a head of 0.55 metres. The auxiliary equipment includes 10 racks of flap gates to prevent reverse flow, electric controls, remote supervision, testing, installation and maintenance facilities. It is anticipated that the new bypass will allow the Chelan County Public Utility Department, owners of the facility, to phase out all current spills, except for a 16 per cent spill for 40 days each spring for Sockeye salmon which tend to travel too deep to use the bypass. Prior to installation of this new facility, 60 to 70 per cent of average daily flow in the spring and summer had to be sacrificed to accommodate all species of salmon and steelhead, with corresponding losses of power generating capacity

Patient Specific Multiscale Simulations of Blood Flow in Coronary Artery Bypass Surgery

Science.gov (United States)

Bangalore Ramachandra, Abhay; Sankaran, Sethuraman; Kahn, Andrew M.; Marsden, Alison L.

2013-11-01

Coronary artery bypass surgery is performed to revascularize blocked coronary arteries in roughly 400,000 patients per year in the US.While arterial grafts offer superior patency, vein grafts are used in more than 70% of procedures, as most patients require multiple grafts. Vein graft failure (approx. 50% within 10 years) remains a major clinical issue. Mounting evidence suggests that hemodynamics plays a key role as a mechano-biological stimulus contributing to graft failure. However, quantifying relevant hemodynamic quantities (e.g. wall shear stress) invivo is not possible directly using clinical imaging techniques. We numerically compute graft hemodynamics in a cohort of 3-D patient specific models using a stabilized finite element method. The 3D flow domain is coupled to a 0D lumped parameter circulatory model. Boundary conditions are tuned to match patient specific blood pressures, stroke volumes & heart rates. Results reproduce clinically observed coronary flow waveforms. We quantify differences in multiple hemodynamic quantities between arterial & venous grafts & discuss possible correlations between graft hemodynamics & clinically observed graft failure.Such correlations will provide further insight into mechanisms of graft failure and may lead to improved clinical outcomes.

Impact of mean arterial pressure on sublingual microcirculation during cardiopulmonary bypass - secondary outcome from a randomised clinical trial

DEFF Research Database (Denmark)

Holmgaard, Frederik; Vedel, Anne G; Ravn, Hanne Berg

2018-01-01

. METHODS: Thirty-six cardiac surgery patients undergoing coronary artery bypass grafting were included and randomised to either low (40-50 mmHg) or high (70-80 mmHg) mean arterial pressure during cardiopulmonary bypass. Sidestream Dark Field video images were recorded from the sublingual mucosa. Recordings...... were analysed in a blinded fashion to quantify microcirculatory variables. RESULTS: Mean arterial pressure during cardiopulmonary bypass in the low target group was 45.0 mmHg (SD 5.3) vs. 67.2 mmHg (SD 8.9) in the high target group. We found no significant difference between the two groups......OBJECTIVE: In this substudy of a randomised, clinical trial, we explored the sublingual microcirculation during cardiac surgery at two different levels of blood pressure. We hypothesised that a higher mean arterial pressure during cardiopulmonary bypass would cause higher Microvascular Flow Index...

Heart bypass surgery

Science.gov (United States)

Off-pump coronary artery bypass; OPCAB; Beating heart surgery; Bypass surgery - heart; CABG; Coronary artery bypass graft; Coronary artery bypass surgery; Coronary bypass surgery; Coronary artery disease - CABG; CAD - CABG; Angina - ...

A Bovine Hemoglobin-Based Oxygen Carrier as Pump Prime for Cardiopulmonary Bypass: Reduced Systemic Lactic Acidosis and Improved Cerebral Oxygen Metabolism During Low-flow in a Porcine Model

Science.gov (United States)

2010-11-10

1 A bovine hemoglobin-based oxygen carrier as pump prime for cardiopulmonary bypass: reduced systemic lactic acidosis and improved cerebral...2010 2. REPORT TYPE Final Report 3. DATES COVERED (From - To) June 2007 - November 2010 4. TITLE AND SUBTITLE A bovine hemoglobin-based oxygen...carrier as pump prime for cardiopulmonary bypass: reduced systemic lactic acidosis and improved cerebral oxygen metabolism during low-flow in a

Numerical simulation of an alternative to prevent hydrates formation in a bypass section

Energy Technology Data Exchange (ETDEWEB)

Almeida, Lucilla Coelho; Oliveira Junior, Joao Americo Aguirre; Fonte, Clarissa Bergman [Engineering Simulation and Scientific Software Ltda. (ESSS), Florianopolis, SC (Brazil); Silva, Fabricio Soares da; Moraes, Carlos Alberto Capela [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)

2012-07-01

This work presents the use of Computational Fluid Dynamics to evaluate the feasibility of MEG (monoethylene glycol) injection as an alternative to prevent hydrate formation in a bypass section, present in an inlet module of a separation device of a subsea separation system. As the bypass section is open to the main pipeline, MEG will probably be dragged due to secondary flows generated by the main flow stream. The MEG removal rate is estimated, as well as the internal heat transfer between the currents and the heat loss to the external environment in order to estimate the temperature in the equipment. In a first step, the MEG removal was evaluated considering the heat transfer between the liquid phase (composed of water, oil and MEG) and the gas phase as well as the heat transfer by forced convection to the external environment. In a second step, the influence of a thermal insulation layer around the bypass line, reducing the heat loss to the external environment, was studied. Both simulations (with or without thermal insulation) showed the establishment of secondary flows in the open connection between the main line and bypass line, promoting the removal of MEG from the bypass section and enabling other components of the liquid phase and/or gas to enter in the bypass line. This MEG removal is faster when thermal isolation was considered, due to the fact that higher temperatures are established in the bypass, maintaining the liquid phase with lower densities and viscosities. With regard to temperature, the insulation was able to keep higher temperatures at the bypass line than those obtained without insulation, indicating that the combination of MEG injection and thermal insulation may be able to avoid the critical condition for hydrate formation. (author)

Optimal design and installation of ultra high bypass ratio turbofan nacelle

Science.gov (United States)

Savelyev, Andrey; Zlenko, Nikolay; Matyash, Evgeniy; Mikhaylov, Sergey; Shenkin, Andrey

2016-10-01

The paper is devoted to the problem of designing and optimizing the nacelle of turbojet bypass engine with high bypass ratio and high thrust. An optimization algorithm EGO based on development of surrogate models and the method for maximizing the probability of improving the objective function has been used. The designing methodology has been based on the numerical solution of the Reynolds equations system. Spalart-Allmaras turbulence model has been chosen for RANS closure. The effective thrust losses has been uses as an objective function in optimizing the engine nacelle. As a result of optimization, effective thrust has been increased by 1.5 %. The Blended wing body aircraft configuration has been studied as a possible application. Two variants of the engine layout arrangement have been considered. It has been shown that the power plant changes the pressure distribution on the aircraft surface. It results in essential diminishing the configuration lift-drag ratio.

Flow and wall shear stress in end-to-side and side-to-side anastomosis of venous coronary artery bypass grafts

Directory of Open Access Journals (Sweden)

Poulikakos Dimos

2007-09-01

Full Text Available Abstract Purpose Coronary artery bypass graft (CABG surgery represents the standard treatment of advanced coronary artery disease. Two major types of anastomosis exist to connect the graft to the coronary artery, i.e., by using an end-to-side or a side-to-side anastomosis. There is still controversy because of the differences in the patency rates of the two types of anastomosis. The purpose of this paper is to non-invasively quantify hemodynamic parameters, such as mass flow and wall shear stress (WSS, in end-to-side and side-to-side anastomoses of patients with CABG using computational fluid dynamics (CFD. Methods One patient with saphenous CABG and end-to-side anastomosis and one patient with saphenous CABG and side-to-side anastomosis underwent 16-detector row computed tomography (CT. Geometric models of coronary arteries and bypasses were reconstructed for CFD analysis. Blood flow was considered pulsatile, laminar, incompressible and Newtonian. Peri-anastomotic mass flow and WSS were quantified and flow patterns visualized. Results CFD analysis based on in-vivo CT coronary angiography data was feasible in both patients. For both types of CABG, flow patterns were characterized by a retrograde flow into the native coronary artery. WSS variations were found in both anastomoses types, with highest WSS values at the heel and lowest WSS values at the floor of the end-to-side anastomosis. In contrast, the highest WSS values of the side-to-side anastomosis configuration were found in stenotic vessel segments and not in the close vicinity of the anastomosis. Flow stagnation zones were found in end-to-side but not in side-to-side anastomosis, the latter also demonstrating a smoother stream division throughout the cardiac cycle. Conclusion CFD analysis of venous CABG based on in-vivo CT datasets in patients was feasible producing qualitative and quantitative information on mass flow and WSS. Differences were found between the two types of anastomosis

Intraoperative transit-time flow measurement is not altered in venous bypass grafts covered by the eSVS mesh.

Science.gov (United States)

Emery, Robert W; Solien, Eric

2013-01-01

The aim of this study was to determine whether the eSVS Mesh interferes with transit-time flow measurement (TTFM) assessing intraoperative coronary vein graft patency. In four swine undergoing off-pump bypass grafting to the anterior descending coronary artery, five TTFMs were sequentially obtained on meshed and bare grafts at baseline and under Dobutamine stress at five separate locations on the graft in each animal. The Medistim VeriQ was used for TTFM. The grafts were examined for patency after the swine were killed. There was no difference in hemodynamics or TTFM either at baseline or under Dobutamine stress between the eSVS Mesh covered and uncovered grafts. Dobutamine, however, significantly increased hemodynamics and graft flow parameters measured from baseline. The eSVS Mesh does not interfere with Doppler flow measurement in covered coronary vein grafts.

Preliminary Study on Acoustic Detection of Faults Experienced by a High-Bypass Turbofan Engine

Science.gov (United States)

Boyle, Devin K.

2014-01-01

The vehicle integrated propulsion research (VIPR) effort conducted by NASA and several partners provided an unparalleled opportunity to test a relatively low TRL concept regarding the use of far field acoustics to identify faults occurring in a high bypass turbofan engine. Though VIPR Phase II ground based aircraft installed engine testing wherein a multitude of research sensors and methods were evaluated, an array of acoustic microphones was used to determine the viability of such an array to detect failures occurring in a commercially representative high bypass turbofan engine. The failures introduced during VIPR testing included commanding the engine's low pressure compressor (LPC) exit and high pressure compressor (HPC) 14th stage bleed values abruptly to their failsafe positions during steady state

Effects of levosimendan on glomerular filtration rate, renal blood flow, and renal oxygenation after cardiac surgery with cardiopulmonary bypass: a randomized placebo-controlled study.

Science.gov (United States)

Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

2013-10-01

Acute kidney injury develops in a large proportion of patients after cardiac surgery because of the low cardiac output syndrome. The inodilator levosimendan increases cardiac output after cardiac surgery with cardiopulmonary bypass, but a detailed analysis of its effects on renal perfusion, glomerular filtration, and renal oxygenation in this group of patients is lacking. We therefore evaluated the effects of levosimendan on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen demand/supply relationship, i.e., renal oxygen extraction, early after cardiac surgery with cardiopulmonary bypass. Prospective, placebo-controlled, and randomized trial. Cardiothoracic ICU of a tertiary center. Postcardiac surgery patients (n=30). The patients were randomized to receive levosimendan, 0.1 µg/kg/min after a loading dose of 12 µg/kg (n=15), or placebo (n=15). The experimental procedure started 4-6 hours after surgery in the ICU during propofol sedation and mechanical ventilation. Systemic hemodynamic were evaluated by a pulmonary artery thermodilution catheter. Renal blood flow and glomerular filtration rate were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA, respectively. Central venous pressure was kept constant by colloid/crystalloid infusion. Compared to placebo, levosimendan increased cardiac index (22%), stroke volume index (15%), and heart rate (7%) and decreased systemic vascular resistance index (21%), whereas mean arterial pressure was not affected. Levosimendan induced significant increases in renal blood flow (12%, prenal vascular resistance (18%, prenal oxygen consumption, or renal oxygen extraction, compared to placebo. After cardiac surgery with cardiopulmonary bypass, levosimendan induces a vasodilation, preferentially of preglomerular resistance vessels, increasing both renal blood flow and glomerular filtration rate without jeopardizing renal oxygenation. Due to its

Utility of pulmonary venous flow diastolic deceleration time in an adult patient undergoing surgical closure of atrial septal defect and coronary artery bypass grafting

Directory of Open Access Journals (Sweden)

Dharmesh R Agrawal

2013-01-01

Full Text Available Acute left ventricular (LV failure has been reported after surgical closure of atrial septal defect (ASD in adult patients. We report acute LV failure in a 56 year old gentleman following coronary artery bypass grafting (CABG and surgical closure of ASD. Transesophageal echocardiography examination of the patient following closure of ASD and CABG showed a residual ASD and a shunt (Qp :Qs = 1.5. The residual ASD was closed after re-institution of cardiopulmonary bypass (CPB under cardioplegic cardiac arrest. However, the patient did not tolerate closure of the residual ASD. The CPB was re-established and under cardioplegic cardiac arrest residual ASD was reopened to create a fenestration. This time patient was weaned easily from CPB. Postoperatively, 16 hours after extubation, patient became hemodynamically unstable, the patient was electively put on ventilator and intra-aortic balloon pump. Later the patient was weaned off successfully from ventilator. Retrospective analysis of pulmonary venous flow diastolic deceleration time (PVDT D recorded during prebypass period measured 102 msec suggestive of high left atrial pressure which indicate possibility of LV failure after ASD closure.

Study on core flow distribution of the reference core design Mark-III of experimental multi-purpose VHTR

International Nuclear Information System (INIS)

Satoh, Sadao; Arai, Taketoshi; Miyamoto, Yoshiaki; Hirano, Mitsumasa

1977-01-01

Concerning the coolant flow distribution between fuel channels and other flow paths in the core, designated as Reference Core Mark-III of the Multi-purpose Experimental Very High Temperature Reactor, thermal analysis has been made of the control rods and other steel structures around the core to find the coolant flow rates (bypass flow) necessary to cool them to their safe operating temperatures. Calculations showed that adequate cooling could be achieved in the Mark-III Core by the bypass flow of 8% of the total reactor coolant flow, 4% each for the control-rod channels and for other structures. The thermal and coolant flow design bases, including the assumption of a 10% bypass flow, were thus confirmed to first approximation. (auth.)

Off-pump Coronary Artery Bypass Graft in a High Risk Patient ...

African Journals Online (AJOL)

On-pump coronary artery bypass graft (CABG) entails the use of cardiopulmonary bypass (CPB). The procedure is safe but it's not without complications like neurocognitive deficits, cerebrovascular accidents, myocardial ischemic injury and activation of inflammatory pathways that contribute to pulmonary, renal, hematologic ...

A computational fluid dynamics study on hemodynamics for different locations of the distal anastomosis of a bypass nearby a collateral vessel in the femoropopliteal area.

Science.gov (United States)

Rivera, J; van der Graaf, G B; Escudero, J R; Bellmunt, S; van de Vosse, F

2014-11-01

Revascularization of the femoropopliteal sector is often performed by the placement of a bypass. In this paper, we have studied the effects of hemodynamics on patency of the bypass for different positions of the distal anastomosis close to a collateral artery. Computational fluid dynamics (CFD) are used for this study. The cardiac cycle-averaged wall shear stress (WSS) and oscillation index (OSI) have been analyzed. Low WSS and high OSI may increase the risk of intimal hyperplasia (IH), which may reduce bypass patency. From the CFD simulations, spots of low WSS and high OSI are found within and near the entrance of the collateral artery, near the suture line, at the floor, toe, and heel. We regarded flow ratios of 20:80 and of 35:65. It is found that for the high flow ratio anastomosis located proximal to the collateral artery is clearly more advantageous. However for the low flow ratio anastomosis located distal to the collateral artery seems to be slightly more advantageous, the results are less conclusive. One of the studied flow geometries has been validated by in vitro experiments using a time resolved particle image velocimetry technique. Velocity fields from these experiments are in good agreement with the CFD results. Copyright © 2014 John Wiley & Sons, Ltd.

Fuel assembly outlet temperature profile influence on core by-pass flow and power distribution determination in WWER -440 reactors

International Nuclear Information System (INIS)

Petenyi, V.; Klucarova, K.; Remis, J.

2003-01-01

The in core instrumentation of the WWER-440 reactors consists of the thermocouple system and the system of self powered detectors (SPD). The thermocouple systems are positioned about 50 cm above the fuel bundle upper flow-mixing grid. The usual assumption is that, the coolant is well mixed in the Tc location, i.e. the temperature is constant through the flow cross-section area. The present evaluations by using the FLUENT 5.5.14 code reveal that, this assumption is not fulfilled. There exists a temperature profile that depends on fuel assembly geometry and on inner power profile of the fuel assembly. The paper presents the estimation of this effect and its influence on the core power distribution and the core by-pass flow determination. Comparison with measurements in Mochovce NPP will also be a part of this presentation (Authors)

Effect of STA-MCA bypass based on the motor activation SPECT

International Nuclear Information System (INIS)

Kawaguchi, Shoichiro; Uranishi, Ryunosuke; Sakaki, Toshisuke; Imai, Teruhiko; Ohishi, Hajime

1999-01-01

The effect of STA-MCA bypass for ischemic cerebrovascular diseases (CVDs) on pure motor function using motor activation SPECT was evaluated and analyzed, and this effect with the resting cerebral blood flow and reserved capacity was compared. Motor activation SPECT were carried out on 22 cases with STA-MCA bypass for symptomatic ischemic CVDs. All motors activation SPECT using the finger opposition task on the affected side were performed before bypass, at 1 month, and 3 months after the bypass. Visual inspection was used to determine whether the result of the motor activation SPECT was as negative or positive. The activated region was detected anatomically precisely by superimposing the SPECT on the MRI. Before this study, the same examination was performed on normal controls. In controls, 91% showed the activated area on the sensorimotor cortex after the finger opposition tasks. Before bypass, the resting SPECT revealed reduction of cerebral blood flow (CBF) on the affected side in all cases. All cases also showed a disturbed response to acetazolamide (ACZ). Nine cases were positive in the motor activation SPECT. One month after bypass, the resting CBF increased in 11 cases. Seven showed preoperative positive motor activation. Fifteen cases were positive in the motor activation SPECT. Three months after bypass, 20 cases showed improvement in the resting CBF, and 19 cases were positive in the motor activation SPECT. Ten cases were negative in the preoperative motor activation SPECT. At one month after surgery, ACZ activation SPECT was performed in 12 cases. Five showed improvement of the response to ACZ. At 3 months after surgery, 8 of 12 cases treated with ACZ activation SPECT showed improved response to ACZ. In most of the cases, improved response to ACZ could be seen after response to motor activation improved. STA-MCA bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT. (K.H.)

Effect of STA-MCA bypass based on the motor activation SPECT

Energy Technology Data Exchange (ETDEWEB)

Kawaguchi, Shoichiro; Uranishi, Ryunosuke; Sakaki, Toshisuke; Imai, Teruhiko; Ohishi, Hajime [Nara Medical Univ., Kashihara (Japan)

1999-07-01

The effect of STA-MCA bypass for ischemic cerebrovascular diseases (CVDs) on pure motor function using motor activation SPECT was evaluated and analyzed, and this effect with the resting cerebral blood flow and reserved capacity was compared. Motor activation SPECT were carried out on 22 cases with STA-MCA bypass for symptomatic ischemic CVDs. All motors activation SPECT using the finger opposition task on the affected side were performed before bypass, at 1 month, and 3 months after the bypass. Visual inspection was used to determine whether the result of the motor activation SPECT was as negative or positive. The activated region was detected anatomically precisely by superimposing the SPECT on the MRI. Before this study, the same examination was performed on normal controls. In controls, 91% showed the activated area on the sensorimotor cortex after the finger opposition tasks. Before bypass, the resting SPECT revealed reduction of cerebral blood flow (CBF) on the affected side in all cases. All cases also showed a disturbed response to acetazolamide (ACZ). Nine cases were positive in the motor activation SPECT. One month after bypass, the resting CBF increased in 11 cases. Seven showed preoperative positive motor activation. Fifteen cases were positive in the motor activation SPECT. Three months after bypass, 20 cases showed improvement in the resting CBF, and 19 cases were positive in the motor activation SPECT. Ten cases were negative in the preoperative motor activation SPECT. At one month after surgery, ACZ activation SPECT was performed in 12 cases. Five showed improvement of the response to ACZ. At 3 months after surgery, 8 of 12 cases treated with ACZ activation SPECT showed improved response to ACZ. In most of the cases, improved response to ACZ could be seen after response to motor activation improved. STA-MCA bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT. (K.H.)

Warfarin improves the outcome of infrainguinal vein bypass grafting at high risk for failure.

Science.gov (United States)

Sarac, T P; Huber, T S; Back, M R; Ozaki, C K; Carlton, L M; Flynn, T C; Seeger, J M

1998-09-01

Patients with marginal venous conduit, poor arterial runoff, and prior failed bypass grafts are at high risk for infrainguinal graft occlusion and limb loss. We sought to evaluate the effects of anticoagulation therapy after autogenous vein infrainguinal revascularization on duration of patency, limb salvage rates, and complication rates in this subset of patients. This randomized prospective trial was performed in a university tertiary care hospital and in a Veterans Affairs Hospital. Fifty-six patients who were at high risk for graft failure were randomized to receive aspirin (24 patients, 27 bypass grafts) or aspirin and warfarin (WAR; 32 patients, 37 bypass grafts). All patients received 325 mg of aspirin each day, and the patients who were randomized to warfarin underwent anticoagulation therapy with heparin immediately after surgery and then were started on warfarin therapy to maintain an international normalized ratio between 2 and 3. Perioperative blood transfusions and complications were compared with the Student t test or with the chi2 test. Graft patency rates, limb salvage rates, and survival rates were compared with the Kaplan-Meier method and the log-rank test. Sixty-one of the 64 bypass grafts were performed for rest pain or tissue loss, and 3 were performed for short-distance claudication. There were no differences between the groups in ages, indications, bypass graft types, risk classifications (ie, conduit, runoff, or graft failure), or comorbid conditions (except diabetes mellitus). The cumulative 5-year survival rate was similar between the groups. The incidence rate of postoperative hematoma (32% vs 3.7%; P = .004) was greater in the WAR group, but no differences were seen between the WAR group and the aspirin group in the number of packed red blood cells transfused, in the incidence rate of overall nonhemorrhagic wound complications, or in the overall complication rate (62% vs 52%). The immediate postoperative primary graft patency rates (97

The Promise and Challenges of Ultra High Bypass Ratio Engine Technology and Integration

Science.gov (United States)

Hughes, Chris

2011-01-01

In this presentation, an overview of the research being conducted by the ERA Project in Ultra High Bypass aircraft propulsion and in partnership with Pratt & Whitney with their Geared TurboFan (GTF) is given. The ERA goals are shown followed by a discussion of what areas need to be addressed on the engine to achieve the goals and how the GTF is uniquely qualified to meet the goals through a discussion of what benefits the cycle provides. The first generation GTF architecture is then shown highlighting the areas of collaboration with NASA, and the fuel burn, noise and emissions reductions possible based on initial static ground test and flight test data of the first GTF engine. Finally, a 5 year technology roadmap is presented focusing on Ultra High Bypass propulsion technology research areas that are being pursued and being planned by ERA and P&W under their GTF program.

Effects of selected design variables on three ramp, external compression inlet performance. [boundary layer control bypasses, and mass flow rate

Science.gov (United States)

Kamman, J. H.; Hall, C. L.

1975-01-01

Two inlet performance tests and one inlet/airframe drag test were conducted in 1969 at the NASA-Ames Research Center. The basic inlet system was two-dimensional, three ramp (overhead), external compression, with variable capture area. The data from these tests were analyzed to show the effects of selected design variables on the performance of this type of inlet system. The inlet design variables investigated include inlet bleed, bypass, operating mass flow ratio, inlet geometry, and variable capture area.

Diabetic patients have abnormal cerebral autoregulation during cardiopulmonary bypass

International Nuclear Information System (INIS)

Croughwell, N.; Lyth, M.; Quill, T.J.; Newman, M.; Greeley, W.J.; Smith, L.R.; Reves, J.G.

1990-01-01

We tested the hypothesis that insulin-dependent diabetic patients with coronary artery bypass graft surgery experience altered coupling of cerebral blood flow and oxygen consumption. In a study of 23 patients (11 diabetics and 12 age-matched controls), cerebral blood flow was measured using 133Xe clearance during nonpulsatile, alpha-stat blood gas managed cardiopulmonary bypass at the conditions of hypothermia and normothermia. In diabetic patients, the cerebral blood flow at 26.6 +/- 2.42 degrees C was 25.3 +/- 14.34 ml/100 g/min and at 36.9 +/- 0.58 degrees C it was 27.3 +/- 7.40 ml/100 g/min (p = NS). The control patients increased cerebral blood flow from 20.7 +/- 6.78 ml/100 g/min at 28.4 +/- 2.81 degrees C to 37.6 +/- 8.81 ml/100 g/min at 36.5 +/- 0.45 degrees C (p less than or equal to 0.005). The oxygen consumption was calculated from jugular bulb effluent and increased from hypothermic values of 0.52 +/- 0.20 ml/100 g/min in diabetics to 1.26 +/- 0.28 ml/100 g/min (p = 0.001) at normothermia and rose from 0.60 +/- 0.27 to 1.49 +/- 0.35 ml/100 g/min (p = 0.0005) in the controls. Thus, despite temperature-mediated changes in oxygen consumption, diabetic patients did not increase cerebral blood flow as metabolism increased. Arteriovenous oxygen saturation gradients and oxygen extraction across the brain were calculated from arterial and jugular bulb blood samples. The increase in arteriovenous oxygen difference between temperature conditions in diabetic patients and controls was significantly different (p = 0.01). These data reveal that diabetic patients lose cerebral autoregulation during cardiopulmonary bypass and compensate for an imbalance in adequate oxygen delivery by increasing oxygen extraction

Analysis of the force exercised in pipes by accumulation of water in the head stock of turbine bypass

International Nuclear Information System (INIS)

Cecenas F, M.; Ovando C, R.; Campos G, R. M.

2011-11-01

The head stock and valves of turbine bypass allow canalize the main vapor coming from the reactor toward the condenser, without carrying out work in the turbo-generator. In this work is assumed that is accumulates condensed in the head stock during a time period in which the bypass system does not operate. For operation maneuvers, the opening of the bypass is demanded, for what the accumulated water is suddenly dragged by the vapor to high pressure coming from the reactor toward the condenser, which operates to inferior pressures to the atmospheric. The generated flow produces a mechanical effort in the lines and its supports. By means of the RELAP5 code the bypass system is modeled, the discharge transitory to the condenser is simulated and the speeds of the mixture water/vapor are calculated. Processing the exit of RELAP5 the mechanical effort that is subjected the pipe is calculated, and the study is complemented with a sensibility analysis to the quantity of stored water in the volume of the bypass head stock. (Author)

Transit-time flow measurement as a predictor of coronary bypass graft failure at one year angiographic follow-up

DEFF Research Database (Denmark)

Lehnert, Per; Møller, Christian H; Damgaard, Sune

2015-01-01

on graft vessel type, anastomatic configuration, and coronary artery size. RESULTS: Nine hundred eighty-two coronary anastomoses were performed of which 12% had signs of graft failure at one year angiographic follow-up. In internal mammary arteries (IMAs), analysis showed a 4% decrease in graft failure......BACKGROUND: Transit-time flow measurement (TTFM) is a commonly used intraoperative method for evaluation of coronary artery bypass graft (CABG) anastomoses. This study was undertaken to determine whether TTFM can also be used to predict graft patency at one year postsurgery. METHODS: Three hundred...... forty-five CABG patients with intraoperative graft flow measurements and one year angiographic follow-up were analyzed. Graft failure was defined as more than 50% stenosis including the "string sign." Logistic regression analysis was used to analyze the risk of graft failure after one year based...

Extracranial–intracranial bypass for Takayasu’s arteritis: A case report

Directory of Open Access Journals (Sweden)

Richard M. Young, M.D.

2014-12-01

Conclusion: STA–MCA bypass to enhance cerebral blood flow in the setting of stroke symptoms due to Takayasu’s arteritis can serve as a bridge before definitive cardiothoracic treatment of the great vessels.

The effect of EC-IC bypass surgery on resting cerebral blood flow and cerebrovascular reserve capacity studied with stable Xe-CT and acetazolamide test

Energy Technology Data Exchange (ETDEWEB)

Yamashita, T.; Kashiwagi, S.; Nakano, S.; Takasago, T.; Abiko, S.; Shiroyama, Y.; Hayashi, M.; Ito, H. (Yamaguchi Univ. School of Medicine (Japan). Dept. of Neurosurgery)

1991-06-01

Cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) were measured by stable xenon computerized tomography (Xe-CT) and acetazolamide test in 15 patients with cerebrovascular disease before and after extracranial-intracranial (EC-IC) bypass surgery for minor stroke, reversible ischemic neurological deficit or transient ischemic attack. All had angiographically shown occlusive lesions of the major arterial trunk. In the present series, global analysis showed that the bypass did not increase the resting rCBF, but did increase the rCRC. We divided the patients into four groups according to the preoperative resting rCBF and rCRC. All 3 patients with normal resting rCBF and reduced rCRC showed postoperative improvement of rCRC. Of 6 patients with reduced CBF and reduced CRC, three had postoperative increase in resting CBF and four had increased CRC. One of two patients with reduced CBF and normal CRC showed only an increase in CRC. We propose that reduced CRC or reduced CBF with reduced CRC are criteria for selection of candidates for bypass surgery. We conclude that Xe-CT with the Diamox test is a useful and simple method for evaluating cerebral hemodynamics. Preoperative grouping with a combination of preoperative resting rCBF and preoperative rCRC is useful for predicting the effect of EC-IC bypass surgery. (orig.).

Development of a detailed core flow analysis code for prismatic fuel reactors

International Nuclear Information System (INIS)

Bennett, R.G.

1990-01-01

The detailed analysis of the core flow distribution in prismatic fuel reactors is of interest for modular high-temperature gas-cooled reactor (MHTGR) design and safety analyses. Such analyses involve the steady-state flow of helium through highly cross-connected flow paths in and around the prismatic fuel elements. Several computer codes have been developed for this purpose. However, since they are proprietary codes, they are not generally available for independent MHTGR design confirmation. The previously developed codes do not consider the exchange or diversion of flow between individual bypass gaps with much detail. Such a capability could be important in the analysis of potential fuel block motion, such as occurred in the Fort St. Vrain reactor, or for the analysis of the conditions around a flow blockage or misloaded fuel block. This work develops a computer code with fairly general-purpose capabilities for modeling the flow in regions of prismatic fuel cores. The code, called BYPASS solves a finite difference control volume formulation of the compressible, steady-state fluid flow in highly cross-connected flow paths typical of the MHTGR

Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions

Science.gov (United States)

Elliott, David M.; Woodward, Richard P.; Podboy, Gary G.

2010-01-01

Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

The Role of Bile After Roux-en-Y Gastric Bypass in Promoting Weight Loss and Improving Glycaemic Control

Science.gov (United States)

Pournaras, Dimitri J.; Glicksman, Clare; Vincent, Royce P.; Kuganolipava, Shophia; Alaghband-Zadeh, Jamie; Mahon, David; Bekker, Jan H.R.; Ghatei, Mohammad A.; Bloom, Stephen R.; Walters, Julian R.F.; le Roux, Carel W.

2012-01-01

Gastric bypass leads to the remission of type 2 diabetes independently of weight loss. Our hypothesis is that changes in bile flow due to the altered anatomy may partly explain the metabolic outcomes of the operation. We prospectively studied 12 patients undergoing gastric bypass and six patients undergoing gastric banding over a 6-wk period. Plasma fibroblast growth factor (FGF)19, stimulated by bile acid absorption in the terminal ileum, and plasma bile acids were measured. In canine and rodent models, we investigated changes in the gut hormone response after altered bile flow. FGF19 and total plasma bile acids levels increased after gastric bypass compared with no change after gastric banding. In the canine model, both food and bile, on their own, stimulated satiety gut hormone responses. However, when combined, the response was doubled. In rats, drainage of endogenous bile into the terminal ileum was associated with an enhanced satiety gut hormone response, reduced food intake, and lower body weight. In conclusion, after gastric bypass, bile flow is altered, leading to increased plasma bile acids, FGF19, incretin. and satiety gut hormone concentrations. Elucidating the mechanism of action of gastric bypass surgery may lead to novel treatments for type 2 diabetes. PMID:22673227

Bypass transition in compressible boundary layers

Science.gov (United States)

Vandervegt, J. J.

1992-01-01

Transition to turbulence in aerospace applications usually occurs in a strongly disturbed environment. For instance, the effects of free-stream turbulence, roughness and obstacles in the boundary layer strongly influence transition. Proper understanding of the mechanisms leading to transition is crucial in the design of aircraft wings and gas turbine blades, because lift, drag and heat transfer strongly depend on the state of the boundary layer, laminar or turbulent. Unfortunately, most of the transition research, both theoretical and experimental, has focused on natural transition. Many practical flows, however, defy any theoretical analysis and are extremely difficult to measure. Morkovin introduced in his review paper the concept of bypass transition as those forms of transition which bypass the known mechanisms of linear and non-linear transition theories and are currently not understood by experiments. In an effort to better understand the mechanisms leading to transition in a disturbed environment, experiments are conducted studying simpler cases, viz. the effects of free stream turbulence on transition on a flat plate. It turns out that these experiments are very difficult to conduct, because generation of free stream turbulence with sufficiently high fluctuation levels and reasonable homogeneity is non trivial. For a discussion see Morkovin. Serious problems also appear due to the fact that at high Reynolds numbers the boundary layers are very thin, especially in the nose region of the plate where the transition occurs, which makes the use of very small probes necessary. The effects of free-stream turbulence on transition are the subject of this research and are especially important in a gas turbine environment, where turbulence intensities are measured between 5 and 20 percent, Wang et al. Due to the fact that the Reynolds number for turbine blades is considerably lower than for aircraft wings, generally a larger portion of the blade will be in a laminar

Assessment of Cerebrovascular Reserve before and after STA-MCA Bypass Surgery by SPECT and SPM Analysis

International Nuclear Information System (INIS)

O, Joo-Hyun; Jang, Kyung-Sool; Yoo, Ie-Ryung

2007-01-01

The purpose of this study was to objectively assess the efficacy of superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery using Technetium (Tc)-99m-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients who underwent STA-MCA bypass surgery. Brain perfusion SPECT images obtained at baseline and after the administration of acetazolamide were reconstructed using statistical parametric mapping in 23 patients, both before and after STA-MCA bypass surgery. The clinical outcomes of the surgery were also recorded and compared with the hemodynamic changes. A voxel with an uncorrected p-value of less than 0.001 was considered to be statistically significant. SPECT images of the territory supplied by the bypass graft showed an increase in both cerebrovascular flow and reserve at baseline, and the increase was significantly higher following the administration of acetazolamide. All patients showed improvement of clinical symptoms and increased blood flow to the left temporal, parietal, and frontal cortices as well as the thalamus. Brain SPECT effectively and objectively demonstrated the improved outcomes of STA-MCA bypass surgery, and thus may be used in postoperative analyses

Análisis de predictores independientes del flujo del bypass coronario en pacientes intervenidos de revascularización miocárdica aislada

Directory of Open Access Journals (Sweden)

Stefano Urso

2017-11-01

ni analizado como variable continua ni como variable dicotómica. Abstract: Introduction and objective: The transit time flowmeter allows knowing two parameters: the mean bypass flow and pulsatility index. These two parameters, when altered, can suggest a bypass stenosis. Factors other than the permeability of the anastomosis, as the quality of coronary bed, may alter the flow of bypass and complicates its interpretation. The aim of our study is to analyze the independent predictors of the mean flow of aorto-coronary bypasses. Methods: We collected a retrospective series of 90 consecutive patients who underwent isolated coronary artery bypass grafting by the same surgeon from January 2014 to August 2016. From this series, we have built an electronic database where each record corresponds to one graft and the correspondent single or multiple bypasses. Therefore, we built a database including 185 grafts. Of these, 8 grafts were not analyzed because the flow had not been correctly measured. Therefore, the flow and pulsatility index values of 177 grafts were available for our statistical analysis. Results: Multiple linear regression analysis detected two independent predictors of bypass flow: sequential saphenous vein graft (partial r value: 0.32; P<.0001 and arterial graft (partial r-value: –0.23; P=.0021. Therefore, our model showed a direct correlation between use of saphenous graft with sequential technique and bypass flow and an inverse correlation between arterial graft use and bypass flow. Conclusions: The predictors of aorto-coronary bypass flow are the use of an arterial graft (negative coefficient and the use of a sequential venous graft (positive coefficient. Our statistical model has not identified as a predictor the SYNTAX score nor analyzed as a continuous variable nor as a dichotomous variable. Palabras clave: Cirugía coronaria, SYNTAX score, Flujo Bypass, Keywords: Coronary surgery, SYNTAX score, Bypass flow

Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

International Nuclear Information System (INIS)

Lee, Jeong-Hun; Cho, Hyoung-Kyu; Park, Goon-Cherl

2016-01-01

Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

Development of the loss coefficient correlation for cross flow between graphite fuel blocks in the core of prismatic very high temperature reactor-PMR200

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeong-Hun, E-mail: huny12@snu.ac.kr; Cho, Hyoung-Kyu, E-mail: chohk@snu.ac.kr; Park, Goon-Cherl, E-mail: parkgc@snu.ac.kr

2016-10-15

Highlights: • Cross flow experimental data are produced with wedge-shaped and parallel gaps. • The results of a CFD analysis and experimental data are in good agreement. • Pressure loss coefficient for the cross gap between fuel blocks in PMR200 is found. • A new correlation of the cross flow loss coefficient for PMR200 is proposed. - Abstract: The core of the very high temperature reactor (VHTR) PMR200 (a prismatic modular reactor rated at 200 MW of thermal power) consists of hexagonal prismatic fuel blocks and reflector blocks made of graphite. If the core bypass flow ratio increases, the coolant channel flow is decreased and can then lower the heat removal efficiency, resulting in a locally increased fuel block temperature. The coolant channels in the fuel blocks are connected to bypass gaps by the cross gap, complicating flow distribution in the VHTR core. Therefore, reliable estimation of the bypass flow is highly important for the design and safety analysis of the VHTR core. Because of the complexity of the core geometry and gap configuration, it is challenging to predict the flow distribution in the VHTR core. To analyze this flow distribution accurately, it is necessary to determine the cross flow phenomena, and the loss coefficient across the cross gap has to be evaluated to determine the flow distribution in the VHTR core when a lumped parameter code or a flow network analysis code that uses the correlation of the loss coefficient is employed. The purpose of this paper is to develop a loss coefficient correlation applicable to the cross gap in the PMR200 core. The cross flow was evaluated experimentally using the difference between the measured inlet and outlet mass flow rates. Next, the applicability of a commercial computational fluid dynamics (CFD) code, CFX 15, was confirmed by comparing the experimental data and CFD analysis results. To understand the cross flow phenomena, the loss coefficient was evaluated; in the high Reynolds number region

Nuclear reactor core flow baffling

International Nuclear Information System (INIS)

Berringer, R.T.

1979-01-01

A flow baffling arrangement is disclosed for the core of a nuclear reactor. A plurality of core formers are aligned with the grids of the core fuel assemblies such that the high pressure drop areas in the core are at the same elevations as the high pressure drop areas about the core periphery. The arrangement minimizes core bypass flow, maintains cooling of the structure surrounding the core, and allows the utilization of alternative beneficial components such as neutron reflectors positioned near the core

Health and performance of calves with forestomach-bypass fed milk replacer.

Science.gov (United States)

McKinstry, D M; Cason, J L; Albert, T F; Sass, B

1976-02-01

Ten male Holstein calves were placed in groups of two calves each on similarity of age. On calf in each group was subjected to forestomach-bypass surgery at about 1 mo of age. Fortified commercial milk replacer with added minerals and vitamins was fed as the sole diet. The calves were housed indoors on slatted platforms. Weight gain was determined biweekly. Feed intake was determined daily. Necropsies were performed upon termination of the study. Recurrent ruminal bloat, fever, and anorexia of varying degrees and combinations occurred in four of the calves with forestomach bypass. Two of these calves showed slow weight gain. One of the four calves died following acute bloat while the other three calves were sacrificed following repeated episodes of bloat. The time of termination varied between 3 and 10 mo. One calf with forestomach bypass and all control calves appeared healthy throughout the experiment. Necropsies indicated that the ruminal bloat, seen in most of the forestomach-bypass calves, could be attributed to the back-flow of ingesta via the omasal-abomasal orifice. This ingesta appeared to produce gas which became trapped in the bypassed rumen.

Application of laminar flow control to high-bypass-ratio turbofan engine nacelles

Science.gov (United States)

Wie, Y. S.; Collier, F. S., Jr.; Wagner, R. D.

1991-01-01

Recently, the concept of the application of hybrid laminar flow to modern commercial transport aircraft was successfully flight tested on a Boeing 757 aircraft. In this limited demonstration, in which only part of the upper surface of the swept wing was designed for the attainment of laminar flow, significant local drag reduction was measured. This paper addresses the potential application of this technology to laminarize the external surface of large, modern turbofan engine nacelles which may comprise as much as 5-10 percent of the total wetted area of future commercial transports. A hybrid-laminar-flow-control (HLFC) pressure distribution is specified and the corresponding nacelle geometry is computed utilizing a predictor/corrector design method. Linear stability calculations are conducted to provide predictions of the extent of the laminar boundary layer. Performance studies are presented to determine potential benefits in terms of reduced fuel consumption.

Slow and preferential flow in the unsaturated zone and its impact on stable isotope composition

International Nuclear Information System (INIS)

Seiler, K.P.

2001-01-01

Stable isotope methods (δ 18 O and δ 2 H) have been used investigate the importance of bypass flow in the unsaturated zone which leads to unproductive water loss during flood irrigation. Field experiments have been carried out in Jordan and Pakistan in order to determine the occurrence of bypass flow, its amount and its velocity compared to piston flow. Results show that there is not only an advective component of flow (bypass flow) but a diffusive tracer exchange between piston and bypass flow. Infiltration calculations and analysis of tracer distributions are used to show that at the research sites, bypass flow amounts to about 25% of water recharged during winter. This estimate is important as it provides an assessment of the amount of water that passes the root zone and directly recharges groundwater. (author)

Method of treating emissions of a hybrid vehicle with a hydrocarbon absorber and a catalyst bypass system

Science.gov (United States)

Roos, Bryan Nathaniel; Gonze, Eugene V; Santoso, Halim G; Spohn, Brian L

2014-01-14

A method of treating emissions from an internal combustion engine of a hybrid vehicle includes directing a flow of air created by the internal combustion engine when the internal combustion engine is spinning but not being fueled through a hydrocarbon absorber to collect hydrocarbons within the flow of air. When the hydrocarbon absorber is full and unable to collect additional hydrocarbons, the flow of air is directed through an electrically heated catalyst to treat the flow of air and remove the hydrocarbons. When the hydrocarbon absorber is not full and able to collect additional hydrocarbons, the flow of air is directed through a bypass path that bypasses the electrically heated catalyst to conserve the thermal energy stored within the electrically heated catalyst.

The effect of factor VIII deficiencies and replacement and bypass therapies on thrombus formation under venous flow conditions in microfluidic and computational models.

Directory of Open Access Journals (Sweden)

Abimbola A Onasoga-Jarvis

Full Text Available Clinical evidence suggests that individuals with factor VIII (FVIII deficiency (hemophilia A are protected against venous thrombosis, but treatment with recombinant proteins can increase their risk for thrombosis. In this study we examined the dynamics of thrombus formation in individuals with hemophilia A and their response to replacement and bypass therapies under venous flow conditions. Fibrin and platelet accumulation were measured in microfluidic flow assays on a TF-rich surface at a shear rate of 100 s⁻¹. Thrombin generation was calculated with a computational spatial-temporal model of thrombus formation. Mild FVIII deficiencies (5-30% normal levels could support fibrin fiber formation, while severe (1 nM, but too low to support fibrin formation (<10 nM. In the absence of platelets, fibrin formation was not supported even at normal FVIII levels, suggesting platelet adhesion is necessary for fibrin formation. Individuals treated by replacement therapy, recombinant FVIII, showed normalized fibrin formation. Individuals treated with bypass therapy, recombinant FVIIa, had a reduced lag time in fibrin formation, as well as elevated fibrin accumulation compared to healthy controls. Treatment of rFVIIa, but not rFVIII, resulted in significant changes in fibrin dynamics that could lead to a prothrombotic state.

Impact of competitive flow on wall shear stress in coronary surgery: computational fluid dynamics of a LIMA-LAD model.

Science.gov (United States)

Nordgaard, Håvard; Swillens, Abigail; Nordhaug, Dag; Kirkeby-Garstad, Idar; Van Loo, Denis; Vitale, Nicola; Segers, Patrick; Haaverstad, Rune; Lovstakken, Lasse

2010-12-01

Competitive flow from native coronary vessels is considered a major factor in the failure of coronary bypass grafts. However, the pathophysiological effects are not fully understood. Low and oscillatory wall shear stress (WSS) is known to induce endothelial dysfunction and vascular disease, like atherosclerosis and intimal hyperplasia. The aim was to investigate the impact of competitive flow on WSS in mammary artery bypass grafts. Using computational fluid dynamics, WSS was calculated in a left internal mammary artery (LIMA) graft to the left anterior descending artery in a three-dimensional in vivo porcine coronary artery bypass graft model. The following conditions were investigated: high competitive flow (non-significant coronary lesion), partial competitive flow (significant coronary lesion), and no competitive flow (totally occluded coronary vessel). Time-averaged WSS of LIMA at high, partial, and no competitive flow were 0.3-0.6, 0.6-3.0, and 0.9-3.0 Pa, respectively. Further, oscillatory WSS quantified as the oscillatory shear index (OSI) ranged from (maximum OSI = 0.5 equals zero net WSS) 0.15 to 0.35, OSI similar to the no competitive flow condition. Graft flow is highly dependent on the degree of competitive flow. High competitive flow was found to produce unfavourable WSS consistent with endothelial dysfunction and subsequent graft narrowing and failure. Partial competitive flow, however, may be better tolerated as it was found to be similar to the ideal condition of no competitive flow.

Development of flow network analysis code for block type VHTR core by linear theory method

International Nuclear Information System (INIS)

Lee, J. H.; Yoon, S. J.; Park, J. W.; Park, G. C.

2012-01-01

VHTR (Very High Temperature Reactor) is high-efficiency nuclear reactor which is capable of generating hydrogen with high temperature of coolant. PMR (Prismatic Modular Reactor) type reactor consists of hexagonal prismatic fuel blocks and reflector blocks. The flow paths in the prismatic VHTR core consist of coolant holes, bypass gaps and cross gaps. Complicated flow paths are formed in the core since the coolant holes and bypass gap are connected by the cross gap. Distributed coolant was mixed in the core through the cross gap so that the flow characteristics could not be modeled as a simple parallel pipe system. It requires lot of effort and takes very long time to analyze the core flow with CFD analysis. Hence, it is important to develop the code for VHTR core flow which can predict the core flow distribution fast and accurate. In this study, steady state flow network analysis code is developed using flow network algorithm. Developed flow network analysis code was named as FLASH code and it was validated with the experimental data and CFD simulation results. (authors)

Cognitive outcomes in elderly high-risk patients after off-pump versus conventional coronary artery bypass grafting

DEFF Research Database (Denmark)

Jensen, Birte Ostergaard; Hughes, Pia; Rasmussen, Lars S

2006-01-01

It has been suggested that the risk of cerebral dysfunction is less with off-pump coronary artery bypass grafting (OPCAB) than with conventional coronary artery bypass grafting (CCAB). However, evidence for this statement is preliminary, and additional insight is needed.......It has been suggested that the risk of cerebral dysfunction is less with off-pump coronary artery bypass grafting (OPCAB) than with conventional coronary artery bypass grafting (CCAB). However, evidence for this statement is preliminary, and additional insight is needed....

Effect of bypass on the motor activation SPECT compared to the acetazolamide SPECT

International Nuclear Information System (INIS)

Kawaguchi, Shoichiro; Iwahashi, Hideaki; Sakaki, Toshisuke; Imai, Teruhiko; Ohishi, Hajime

2002-01-01

The authors evaluated and analyzed motor activation single photon emission computed tomography (M-SPECT) in ischemic cerebrovascular disease compared to resting and acetazolamide (ACZ) activated SPECT studies. Seventeen cases with STA-MCA bypass performed for ischemic cerebrovascular disease were examined. The SPECT studies consisting of resting, ACZ activation, and motor activation stages were performed before bypass, at 1 month, and 3 months after bypass. The result of the M-SPECT was expressed as negative or positive. Before bypass: In all 17 cases, SPECT studies of the affected side showed reduction of resting cerebral blood flow (CBF) and reduction of cerebrovascular reserve capacity (CVRC). Eight cases were positive in the M-SPECT study. One week after bypass: The resting CBF increased in seven cases. Four showed preoperative positive M-SPECT. Eight cases showed improvement of the CVRC. Twelve cases were positive in M-SPECT, and two were negative in the preoperative M-SPECT. Three months after bypass: Thirteen cases showed improvement in the resting CBF, and fourteen cases showed improvement of the CVRC. Fourteen cases were positive in the M-SPECT, and among these, 6 were negative in the preoperative M-SPECT. There was a discrepancy between the improvement in CVRC and M-SPECT. M-SPECT study can provide information about the degree of hemodynamic compromise and effect of bypass surgery. (author)

Effect of bypass on the motor activation SPECT compared to the acetazolamide SPECT

Energy Technology Data Exchange (ETDEWEB)

Kawaguchi, Shoichiro; Iwahashi, Hideaki; Sakaki, Toshisuke; Imai, Teruhiko; Ohishi, Hajime [Nara Medical Univ., Kashihara (Japan)

2002-03-01

The authors evaluated and analyzed motor activation single photon emission computed tomography (M-SPECT) in ischemic cerebrovascular disease compared to resting and acetazolamide (ACZ) activated SPECT studies. Seventeen cases with STA-MCA bypass performed for ischemic cerebrovascular disease were examined. The SPECT studies consisting of resting, ACZ activation, and motor activation stages were performed before bypass, at 1 month, and 3 months after bypass. The result of the M-SPECT was expressed as negative or positive. Before bypass: In all 17 cases, SPECT studies of the affected side showed reduction of resting cerebral blood flow (CBF) and reduction of cerebrovascular reserve capacity (CVRC). Eight cases were positive in the M-SPECT study. One week after bypass: The resting CBF increased in seven cases. Four showed preoperative positive M-SPECT. Eight cases showed improvement of the CVRC. Twelve cases were positive in M-SPECT, and two were negative in the preoperative M-SPECT. Three months after bypass: Thirteen cases showed improvement in the resting CBF, and fourteen cases showed improvement of the CVRC. Fourteen cases were positive in the M-SPECT, and among these, 6 were negative in the preoperative M-SPECT. There was a discrepancy between the improvement in CVRC and M-SPECT. M-SPECT study can provide information about the degree of hemodynamic compromise and effect of bypass surgery. (author)

Hemodynamic effect of bypass geometry on intracranial aneurysm: A numerical investigation.

Science.gov (United States)

Kurşun, Burak; Uğur, Levent; Keskin, Gökhan

2018-05-01

Hemodynamic analyzes are used in the clinical investigation and treatment of cardiovascular diseases. In the present study, the effect of bypass geometry on intracranial aneurysm hemodynamics was investigated numerically. Pressure, wall shear stress (WSS) and velocity distribution causing the aneurysm to grow and rupture were investigated and the best conditions were tried to be determined in case of bypassing between basilar (BA) and left/right posterior arteries (LPCA/RPCA) for different values of parameters. The finite volume method was used for numerical solutions and calculations were performed with the ANSYS-Fluent software. The SIMPLE algorithm was used to solve the discretized conservation equations. Second Order Upwind method was preferred for finding intermediate point values in the computational domain. As the blood flow velocity changes with time, the blood viscosity value also changes. For this reason, the Carreu model was used in determining the viscosity depending on the velocity. Numerical study results showed that when bypassed, pressure and wall shear stresses reduced in the range of 40-70% in the aneurysm. Numerical results obtained are presented in graphs including the variation of pressure, wall shear stress and velocity streamlines in the aneurysm. Considering the numerical results for all parameter values, it is seen that the most important factors affecting the pressure and WSS values in bypassing are the bypass position on the basilar artery (L b ) and the diameter of the bypass vessel (d). Pressure and wall shear stress reduced in the range of 40-70% in the aneurysm in the case of bypass for all parameters. This demonstrates that pressure and WSS values can be greatly reduced in aneurysm treatment by bypassing in cases where clipping or coil embolization methods can not be applied. Copyright © 2018 Elsevier B.V. All rights reserved.

Measurements of erosion potential using Gust chamber in Yolo Bypass near Sacramento, California

Science.gov (United States)

Work, Paul A.; Schoellhamer, David H.

2018-04-27

 coring equipment used. The available results suggest that Toe Drain soil is highly erodible (low critical shear stress and high erosion rate once initiated) despite being difficult to sample. As a collector of runoff, it also has the potential to accumulate soils eroded from adjacent areas, subsequent to storm events, as flows subside. This deposited material will typically be more erodible than the material that it lands on. The deposition and resuspension of material was not simulated in the testing described here because the applied shear stress increases monotonically during testing.The spatial distribution of mean grain size, loss on ignition, and percent fines of Yolo Bypass soils are also presented. Sediment sampling for this effort was performed by DWR; the U.S. Geological Survey (USGS) performed the sample analysis. These data should thus be considered provisional, but the remainder of the data presented here, and this report, have been through the formal U.S. Geological Survey review process.A separate effort has been made by others to develop numerical model results defining the spatially  varying, time-dependent hydrodynamics in the Yolo Bypass. These model results are being used to quantify shear stress on the soil surface, which together with the Gust chamber results shown here, are used for the DWR Yolo Bypass D-MCM mercury transport model to compute erosion rates for each time step.

Improvements in Low-cost Ultrasonic Measurements of Blood Flow in "by-passes" Using Narrow & Broad Band Transit-time Procedures

Science.gov (United States)

Ramos, A.; Calas, H.; Diez, L.; Moreno, E.; Prohías, J.; Villar, A.; Carrillo, E.; Jiménez, A.; Pereira, W. C. A.; Von Krüger, M. A.

The cardio-pathology by ischemia is an important cause of death, but the re-vascularization of coronary arteries (by-pass operation) is an useful solution to reduce associated morbidity improving quality of life in patients. During these surgeries, the flow in coronary vessels must be measured, using non-invasive ultrasonic methods, known as transit time flow measurements (TTFM), which are the most accurate option nowadays. TTFM is a common intra-operative tool, in conjunction with classic Doppler velocimetry, to check the quality of these surgery processes for implanting grafts in parallel with the coronary arteries. This work shows important improvements achieved in flow-metering, obtained in our research laboratories (CSIC, ICIMAF, COPPE) and tested under real surgical conditions in Cardiocentro-HHA, for both narrowband NB and broadband BB regimes, by applying results of a CYTED multinational project (Ultrasonic & computational systems for cardiovascular diagnostics). mathematical models and phantoms were created to evaluate accurately flow measurements, in laboratory conditions, before our new electronic designs and low-cost implementations, improving previous ttfm systems, which include analogic detection, acquisition & post-processing, and a portable PC. Both regimes (NB and BB), with complementary performances for different conditions, were considered. Finally, specific software was developed to offer facilities to surgeons in their interventions.

A comparison of high-dose and low-dose tranexamic acid antifibrinolytic protocols for primary coronary artery bypass surgery

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Stephen M McHugh

2016-01-01

Full Text Available Background and Aims: Tranexamic acid (TA is used for prophylactic antifibrinolysis in coronary artery bypass surgeries to reduce bleeding. We evaluated the efficacy of two different doses of TA for prophylactic antifibrinolysis in patients undergoing primary coronary artery bypass grafting (CABG surgery in this retrospective cohort study at a tertiary care referral centre. Methods: One-hundred eighty-four patients who underwent primary CABG with cardiopulmonary bypass (CPB via sternotomy between January 2009 and June 2011 were evaluated. Pre-operative patient characteristics, intraoperative data, post-operative bleeding, transfusions, organ dysfunction and 30-day mortality were compared between high-dose TA (30 mg/kg loading dose followed by infusion of 15 mg/kg/h until the end of surgery along with 2 mg/kg priming dose in the bypass circuit and low-dose TA (15 mg/kg loading dose followed by infusion of 6 mg/kg/h until the end of surgery along with 1 mg/kg priming dose in the bypass circuit groups. Univariate comparative analysis of all categorical and continuous variables was performed between the two groups by appropriate statistical tests. Linear and logistic regression analyses were performed to control for the effect of confounding on the outcome variables. Results: Chest tube output, perioperative transfusion of blood products and incidence of re-exploration for bleeding did not differ significantly (P> 0.05 between groups. Post-operative complications and 30-day mortality were comparable between the groups. The presence of cardiogenic shock and increased pre-operative creatinine were found to be associated with increased chest tube output on the post-operative day 2 by multivariable linear regression model. Conclusions: Low-dose TA protocol is as effective as high-dose protocol for antifibrinolysis in patients undergoing primary CABG with CPB.

[Flowmetric assessment of coronary bypass grafts in the conditions of artificial circulation and on the beating heart].

Science.gov (United States)

Bazylev, V V; Nemchenko, E V; Karnakhin, V A; Pavlov, A A; Mikulyak, A I

2016-01-01

Advantages and shortcomings of aortocoronary bypass grafting on the beating heart and in the conditions of artificial circulation (AC) have long been discussed. The data on patency of bypass grafts in the remote period are indicative of comparable results of operations with and without AC or advantages of using AC. In order to determine benefits of each method it is necessary to reveal intraoperative predictors of bypass grafts occlusion in the remote period. We analyzed the results of ultrasound flowmetry of the blood flow through the left internal thoracic artery during bypass grafting of the anterior descending artery with the use of AC and on the beating heart. A retrospective study included a total of 352 patients subdivided into 2 groups: Group One was composed of 120 patients undergoing surgery in the conditions of AC and Group Two comprised 232 patients subjected to similar operations on the beating heart. Blood flow was measured with the help of flowmeter VeryQ MediStim® after termination of AC and inactivation of heparin by protamine, with systolic pressure of 100-110 mm Hg. There were no statistically significant differences between the groups by the diameter and degree of stenosis of the anterior descending artery, diameter of the left internal thoracic artery. The mean volumetric blood flow velocity (Qmean) along the shunts in Group One was higher (p=0.01). No statistically significant differences by the pulsatility index (PI) between the groups were revealed (p=0.2). A conclusion was drawn that coronary bypass grafting of the anterior descending artery by the left internal thoracic artery in the conditions of artificial circulation made it possible to achieve higher volumetric velocity of blood flow through the conduit as compared with operations on the beating heart, with similar resistance index. The immediate results of the operations with the use of the both techniques did not differ.

40 CFR 75.16 - Special provisions for monitoring emissions from common, bypass, and multiple stacks for SO2...

Science.gov (United States)

2010-07-01

... emissions from common, bypass, and multiple stacks for SO2 emissions and heat input determinations. 75.16... emissions from common, bypass, and multiple stacks for SO2 emissions and heat input determinations. (a... maintain an SO2 continuous emission monitoring system and flow monitoring system in the duct to the common...

THE RESPIRATORY SUBSTRATE RHODOQUINOL INDUCES Q-CYCLE BYPASS REACTIONS IN THE YEAST CYTOCHROME bc1 COMPLEX - MECHANISTIC AND PHYSIOLOGICAL IMPLICATIONS

International Nuclear Information System (INIS)

Cape, Jonathan L.; Strahan, Jeff R.; Lenaeus, Michael J.; Yuknis, Brook A.; Le, Trieu T.; Shepherd, Jennifer; Bowman, Michael K.; Kramer, David M.

2005-01-01

The mitochondrial cytochrome bc1 complex catalyzes the transfer of electrons from ubiquinol to cyt c, while generating a proton motive force for ATP synthesis, via the ''Qcycle'' mechanism. Under certain conditions, electron flow through the Q-cycle is blocked at the level of a reactive intermediate in the quinol oxidase site of the enzyme, resulting in ''bypass reactions'', some of which lead to superoxide production. Using analogs of the respiratory substrates, ubiquinol-3 and rhodoquinol-3, we show that the relative rates of Q-cycle bypass reactions in the Saccharomyces cerevisiae cyt bc1 complex are highly dependent, by a factor of up to one hundred-fold, on the properties of the substrate quinol. Our results suggest that the rate of Q-cycle bypass reactions is dependent on the steady state concentration of reactive intermediates produced at the quinol oxidase site of the enzyme. We conclude that normal operation of the Q-cycle requires a fairly narrow window of redox potentials, with respect to the quinol substrate, to allow normal turnover of the complex while preventing potentially damaging bypass reactions

Reversal of severe SPECT asymmetry after venous extra-intracranial high flow bypass in a patient submitted to therapeutic internal carotid occlusion: case report Reversão de importante assimetria ao SPECT após bypass venoso de alto fluxo extra-intracraniano em paciente submetido a oclusão terapêutica da carótida interna: relato de caso

Directory of Open Access Journals (Sweden)

Jorge Marcondes

2001-09-01

Full Text Available Therapeutic occlusion of the internal carotid artery is the main option for the treatment of the symptomatic intracavernous internal carotid artery aneurysms, but the issue of the best way of doing the balloon test occlusion (BTO regarding prediction of future ischemic events remains debatable. Single photon emission computerized tomography (SPECT has been offered as one of the best option of monitoring regional cerebral blood flow (rCBF during the BTO, where severe asymmetry is predictive of delayed ischemia. We describe a case of important SPECT asymmetry during BTO clinically negative and its complete reversal with carotid occlusion after extra-intracranial bypass with high flow safenous vein bypass between the cervical carotid artery and the middle cerebral artery.Oclusão terapêutica carotídea ainda é a principal escolha para o tratamento dos aneurismas sintomáticos da artéria carótida interna ao nível do seio cavernoso.Existem controvérsias em relação à obtenção de testes com maior valor preditivo em relação à complicações isquêmicas futuras durante a realização do teste de oclusão carotídeo por balão. A tomografia computorizada de emissão de fóton único (SPECT tem sido defendida como uma opção para a melhor avaliação do fluxo sanguíneo regional cerebral, onde evidente assimetria é indicativa de isquemia tardia. Descrevemos um caso de importante assimetria ao SPECT durante o teste clinicamente negativo e sua reversão completa após anastomose extra-intracraniana com interposição de veia safena magna (alto fluxo entre a artéria carótida cervical e a artéria cerebral média.

Coronary Bypass Surgery in a 105-Year-Old Patient with Cardiopulmonary Bypass

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Temucin Noyan Ogus

2010-01-01

Full Text Available Coronary artery bypass grafting is one of the routine daily surgical procedures in the current era. Parallel to the increasing life expectancy, cardiac surgery is commonly performed in octogenarians. However, literature consists of only seldom reports of coronary artery bypass grafting in patients above 90 years of age. In this report, we present our management strategy in a 105-year-old patient who underwent coronary artery bypass grafting at our institution.

Partitioning dynamics of unsaturated flows in fractured porous media: Laboratory studies and three-dimensional multi-scale smoothed particle hydrodynamics simulations of gravity-driven flow in fractures

Science.gov (United States)

Kordilla, J.; Bresinsky, L. T.; Shigorina, E.; Noffz, T.; Dentz, M.; Sauter, M.; Tartakovsky, A. M.

2017-12-01

Preferential flow dynamics in unsaturated fractures remain a challenging topic on various scales. On pore- and fracture-scales the highly erratic gravity-driven flow dynamics often provoke a strong deviation from classical volume-effective approaches. Against the common notion that flow in fractures (or macropores) can only occur under equilibrium conditions, i.e., if the surrounding porous matrix is fully saturated and capillary pressures are high enough to allow filling of the fracture void space, arrival times suggest the existence of rapid preferential flow along fractures, fracture networks, and fault zones, even if the matrix is not fully saturated. Modeling such flows requires efficient numerical techniques to cover various flow-relevant physics, such as surface tension, static and dynamic contact angles, free-surface (multi-phase) interface dynamics, and formation of singularities. Here we demonstrate the importance of such flow modes on the partitioning dynamics at simple fracture intersections, with a combination of laboratory experiments, analytical solutions and numerical simulations using our newly developed massively parallel smoothed particle hydrodynamics (SPH) code. Flow modes heavily influence the "bypass" behavior of water flowing along a fracture junction. Flows favoring the formation of droplets exhibit a much stronger bypass capacity compared to rivulet flows, where nearly the whole fluid mass is initially stored within the horizontal fracture. This behavior is demonstrated for a multi-inlet laboratory setup where the inlet-specific flow rate is chosen so that either a droplet or rivulet flow persists. The effect of fluid buffering within the horizontal fracture is presented in terms of dimensionless fracture inflow so that characteristic scaling regimes can be recovered. For both cases (rivulets and droplets), flow within the horizontal fracture transitions into a Washburn regime until a critical threshold is reached and the bypass efficiency

High-Target Versus Low-Target Blood Pressure Management During Cardiopulmonary Bypass to Prevent Cerebral Injury in Cardiac Surgery Patients: A Randomized Controlled Trial.

Science.gov (United States)

Vedel, Anne G; Holmgaard, Frederik; Rasmussen, Lars S; Langkilde, Annika; Paulson, Olaf B; Lange, Theis; Thomsen, Carsten; Olsen, Peter Skov; Ravn, Hanne Berg; Nilsson, Jens C

2018-04-24

Cerebral injury is an important complication after cardiac surgery with the use of cardiopulmonary bypass. The rate of overt stroke after cardiac surgery is 1% to 2%, whereas silent strokes, detected by diffusion-weighted magnetic resonance imaging, are found in up to 50% of patients. It is unclear whether a higher versus a lower blood pressure during cardiopulmonary bypass reduces cerebral infarction in these patients. In a patient- and assessor-blinded randomized trial, we allocated patients to a higher (70-80 mm Hg) or lower (40-50 mm Hg) target for mean arterial pressure by the titration of norepinephrine during cardiopulmonary bypass. Pump flow was fixed at 2.4 L·min -1 ·m -2 . The primary outcome was the total volume of new ischemic cerebral lesions (summed in millimeters cubed), expressed as the difference between diffusion-weighted imaging conducted preoperatively and again postoperatively between days 3 and 6. Secondary outcomes included diffusion-weighted imaging-evaluated total number of new ischemic lesions. Among the 197 enrolled patients, mean (SD) age was 65.0 (10.7) years in the low-target group (n=99) and 69.4 (8.9) years in the high-target group (n=98). Procedural risk scores were comparable between groups. Overall, diffusion-weighted imaging revealed new cerebral lesions in 52.8% of patients in the low-target group versus 55.7% in the high-target group ( P =0.76). The primary outcome of volume of new cerebral lesions was comparable between groups, 25 mm 3 (interquartile range, 0-118 mm 3 ; range, 0-25 261 mm 3 ) in the low-target group versus 29 mm 3 (interquartile range, 0-143 mm 3 ; range, 0-22 116 mm 3 ) in the high-target group (median difference estimate, 0; 95% confidence interval, -25 to 0.028; P =0.99), as was the secondary outcome of number of new lesions (1 [interquartile range, 0-2; range, 0-24] versus 1 [interquartile range, 0-2; range, 0-29] respectively; median difference estimate, 0; 95% confidence interval, 0-0; P =0

Your diet after gastric bypass surgery

Science.gov (United States)

Gastric bypass surgery - your diet; Obesity - diet after bypass; Weight loss - diet after bypass ... You had gastric bypass surgery. This surgery made your stomach smaller by closing off most of your stomach with staples. It changed the way your ...

A system for regulating the pressure of resuperheated steam in high temperature gas-cooled reactor power stations

International Nuclear Information System (INIS)

Braytenbah, A.S.; Jaegines, K.O.

1975-01-01

The invention relates to a system for regulating steam-pressure in the re-superheating portion of a steam-boiler receiving heat from a gas-cooled high temperature nuclear reactor, provided with gas distributing pumps driven by steam-turbines. The system comprises means for generating a pressure signal of desired magnitude for the re-superheating portion, and means for providing a real pressure in the re-superheating portion, means (including a by-passing device) for generating steam-flow rate signal of desired magnitude, a turbine by-pass device comprising a by-pass tapping means for regulating the steam-flow-rate in said turbine according to the desired steam-flow rate signal and means for controlling said by-pass tapping means according to said desired steam-flow-rate signal [fr

Clinical significance of 201Tl reverse redistribution in patients with aorto-coronary bypass surgery

International Nuclear Information System (INIS)

Nishimura, Tsunehiko; Uehara, Tashiisa; Hayashida, Kohei; Kozuka, Takahira

1987-01-01

Detection of myocardial ischemia by the stress thallium scan has traditionally been performed using transient defect analysis on exercise, followed by redistribution studies. Worsening of the 201 Tl myocardial image from exercise to redistribution is referred to as reverse redistribution. In this study, we found reverse redistribution in 10 (21%) of 48 angina pectoris patients who had undergone aortocoronary bypass surgery. The clinical significance of this phenomenon in these patients was investigated in relation to angiographic and surgical findings. Reverse redistribution was found to occur in regions which were supplied by bypass grafts. These areas showed increased coronary blood flow and rapid thallium washout. Our results indicate that a perfusion defect in the bypass region of the redistribution image might be caused by relatively rapid washout in the bypass graft region compared to the adjacent normal myocardium. These results should be considered in the clinical interpretation of stress thallium scans. (orig.)

Evaluation of ECC bypass data with a nonlinear constrained MLE technique

International Nuclear Information System (INIS)

Bishop, T.A.; Collier, R.P.; Kurth, R.E.

1980-01-01

Recently, Battelle's Columbus Laboratories have been involved in scale-model tests of emergency core cooling (ECC) systems for hypothesized loss-of-coolant accidents in pressurized water reactors (PWR). These tests are intended to increase our understanding of ECC bypass, which can occur when steam flow from the reactor core causes the emergency coolant to bypass the core and flow directly to the break. One objective of these experiments is the development of a correlation which relates the flow rate of water penetrating to the core to the steam flow rate. This correlation is derived from data obtained from a 2/15 scale model PWR at various ECC water injection rates, subcoolings, pressures, and steam flows. The general form of the correlation being studied is a modification of the correlation first proposed by Wallis. The correlation model is inherently nonlinear and implicit in form, and the model variables are all subject to error. Therefore, the usual nonlinear analysis techniques are inappropriate. A nonlinear constrained maximum-likelihood-estimation technique has been used to obtain estimates of the model parameters, and a Battelle-developed code, NLINMLE, has been used to analyze the data. The application of this technique is illustrated by sample calculations of estimates of the model parameters and their associated confidence intervals for selected experimental data sets. 5 figures, 7 tables

75 FR 71145 - San Joaquin River Restoration Program: Reach 4B, Eastside Bypass, and Mariposa Bypass Channel and...

Science.gov (United States)

2010-11-22

..., Eastside Bypass, and Mariposa Bypass Channel and Structural Improvements Project, Merced County, CA AGENCY... on the effects of the proposed Reach 4B, Eastside Bypass, and Mariposa Bypass Channel and Structural... Mariposa Bypass with the San Joaquin River (generally referred to as Reach 4B1). The improvements will...

Flow intake control using dry-weather forecast

Science.gov (United States)

Icke, Otto; van Schagen, Kim; Huising, Christian; Wuister, Jasper; van Dijk, Edward; Budding, Arjan

2017-08-01

Level-based control of the influent flow causes peak discharges at a waste water treatment plant (WWTP) after rainfall events. Furthermore, the capacity of the post-treatment is in general smaller than the maximum hydraulic capacity of the WWTP. This results in a significant bypass of the post-treatment during peak discharge. The optimisation of influent flow reduces peak discharge, and increases the treatment efficiency of the whole water cycle, which benefits the surface water quality. In this paper, it is shown that half of the bypasses of the post-treatment can be prevented by predictive control. A predictive controller for influent flow is implemented using the Aquasuitetext">® Advanced Monitoring and Control platform. Based on real-time measured water levels in the sewerage and both rainfall and dry-weather flow (DWF) predictions, a discharge limitation is determined by a volume optimisation technique. For the analysed period (February-September 2016) results at WWTP Bennekom show that about 50 % of bypass volume can be prevented. Analysis of single rainfall events shows that the used approach is still conservative and that the bypass can be even further decreased by allowing discharge limitation during precipitation.

Reproduction of superior sagittal sinus animal model by bypass transplantation of biomaterial graft

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Qing-yong LUO

2011-03-01

Full Text Available Objective To establish the beagles model of superior sagittal sinus bypass graft,and explore the feasibility of reconstruction of superior sagittal sinus with biomaterials using this model.Methods Eight adult male beagles(weight: 12.5-22.0kg were involved in the present study.The superior sagittal sinus was exposed and blocked via bone window,and then anastomosed side-to-end to the biomaterial graft under the dedicated microscope of neurosurgery surgery,expectant treatment such as anti-inflammatory was given for the animals.The digital subtraction venography(DSV and color Doppler flow imaging(CDFI of superior sagittal sinus were performed in 1,2,4 and 8 weeks after the operation.Eight weeks after the operation,all the animals were sacrificed and the material graft was examined histologically.Results The DSV and CDFI of superior sagittal sinus showed that the stomas of 2 beagles were with slight stenosis and high flow velocity,of 1 beagle with small leakage and low flow velocity,while of other 5 beagles were normal.The histological examination showed endothelial cells were growing on the graft and superior sagittal sinus,and crawling toward the lumen of graft 8 weeks after the operation.Conclusion The beagles model of superior sagittal sinus bypass graft was established successfully.The short-term effect of the model was satisfactory,while further work should be performed to determine the long-term effects.

Design and analysis of an axial bypass compressor blade in a supercritical CO2 gas turbine

International Nuclear Information System (INIS)

Ishizuka, Takao; Muto, Yasushi; Aritomi, Masanori; Tsuzuki, Nobuyoshi; Kikura, Hiroshige

2010-01-01

A supercritical carbon dioxide gas turbine can generate power at a high cycle thermal efficiency, even at modest temperatures of 500-550degC. Consequently, a more reliable and economically advantageous power generation system is achieved by coupling with a Na-cooled fast reactor. This paper mainly describes the bypass compressor (a key component) design and thermal hydraulic analysis using CFD (with FLUENT code). Fluid conditions of the bypass compressor are determined by the cycle calculation of this system. Aerodynamic design was conducted using the loss model described by Cohen et al., which enables the use of several stages while providing total adiabatic efficiency of 21 and 87%, respectively. Blade shapes were prepared based on flow angles and chord length obtained for the aerodynamic design. In the CFD analysis, the calculated value of the mass flow rate for each stage was adjusted to that of the design. The value of the design outlet pressure was reached at stage No. 16, which is fewer stages than that for design, No. 21. The difference between these stage numbers is attributed to the three-dimensional effect in design. If these effects are eliminated, then the design calculation yields an almost identical number of stages. Therefore, it was concluded that the existing design method is applicable to the supercritical CO 2 bypass compressor. Furthermore, CFD analysis appears to be an effective aerodynamic design tool, but these conclusions should be verified experimentally. (author)

Influence of Bypass on Thermo-Hydraulics of VVER 440 Fuel Assembly

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Jakubec Jakub

2017-04-01

Full Text Available The paper deals with CFD modelling and simulation of coolant flow within the nuclear reactor VVER 440 fuel assembly. The influence of coolant flow in bypass on the temperature distribution at the outlet of the fuel assembly and pressure drop was investigated. Only steady-state analyses were performed. Boundary conditions are based on operating conditions. ANSYS CFX is chosen as the main CFD software tool, where all analyses are performed.

Optimal Bypass and Cream Skimming.

OpenAIRE

Laffont, Jean-Jacques; Tirole, Jean

1990-01-01

This paper develops a normative model of regulatory policy toward bypass and cream skimming. It analyzes the effects of bypass on second-degree price discrimination, on the rent of the regulated firm, and on the welfare of low-demand customers. It shows that pricing under marginal cost may be optimal for the regulated firm, excessive cream skimming occurs if access to the bypass technology is not regulated, and the prohibition of bypass may increase or decrease the regulated firm's rent. Copy...

Effect of STA-proximal MCA bypass. Improvement of cerebral blood flow and metabolism and neuropsychological function

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Akira; Funayama, Masayuki; Miura, Kazuyuki; Ogasawara, Kuniaki; Suzuki, Michiyasu; Kuroda, Kiyoshi; Sasaki, Toshiaki [Iwate Medical Univ., Morioka (Japan). School of Medicine

1998-11-01

We investigated cerebral blood flow (CBF) and metabolism in patients with hemodynamic ischemia by positron emission tomography (PET) and thermal diffusion flow meter. We also studied neuropsychological functions to evaluate the effects of surgical revascularization. Bypass surgery of the superficial temporal artery to the proximal middle cerebral artery was performed on 26 patients satisfying the following categories: stenosis or occlusive lesion in main cerebral arteries; no marked focus of infarction on CT or MRI. PET was performed before and 1 month after the operation, and CBF, the cerebral metabolic rate of oxygen (CMRO{sub 2}) and oxygen extraction fraction (OEF) were analyzed. Cerebrovascular reserve capacity (CVRC) was also calculated after acetazolamide challenge. CBF during the operation was continuously measured with a thermal diffusion flow meter. CO{sub 2} response of CBF was analyzed before and after anastomosis. Neuropsychological functions were evaluated by Hasegawa dementia scale revised (HDS-R), mini-mental state examination (MMSE) and Wechsler adult intelligence scale revised (WAIS-R). Before the operation, increase in OEF accorded with the decrease in CBF, and a significant relationship between both CBF and CVRC, and OEF and CVRC was found. A decrease in CVRC was noted prior to a decrease in CBF and elevation of OEF. CVRC caused by acetazolamide might reflect CO{sub 2} reactivity. Significant improvement of CBF and CVRC, and normalization of OEF were observed after the operation. Also, significant improvement of neuropsychological function was observed by HDS-R and WAIS-R. Disturbance in neuropsychological function might reflect elevation of OEF. (author)

Effect of STA-proximal MCA bypass. Improvement of cerebral blood flow and metabolism and neuropsychological function

International Nuclear Information System (INIS)

Ogawa, Akira; Funayama, Masayuki; Miura, Kazuyuki; Ogasawara, Kuniaki; Suzuki, Michiyasu; Kuroda, Kiyoshi; Sasaki, Toshiaki

1998-01-01

We investigated cerebral blood flow (CBF) and metabolism in patients with hemodynamic ischemia by positron emission tomography (PET) and thermal diffusion flow meter. We also studied neuropsychological functions to evaluate the effects of surgical revascularization. Bypass surgery of the superficial temporal artery to the proximal middle cerebral artery was performed on 26 patients satisfying the following categories: stenosis or occlusive lesion in main cerebral arteries; no marked focus of infarction on CT or MRI. PET was performed before and 1 month after the operation, and CBF, the cerebral metabolic rate of oxygen (CMRO 2 ) and oxygen extraction fraction (OEF) were analyzed. Cerebrovascular reserve capacity (CVRC) was also calculated after acetazolamide challenge. CBF during the operation was continuously measured with a thermal diffusion flow meter. CO 2 response of CBF was analyzed before and after anastomosis. Neuropsychological functions were evaluated by Hasegawa dementia scale revised (HDS-R), mini-mental state examination (MMSE) and Wechsler adult intelligence scale revised (WAIS-R). Before the operation, increase in OEF accorded with the decrease in CBF, and a significant relationship between both CBF and CVRC, and OEF and CVRC was found. A decrease in CVRC was noted prior to a decrease in CBF and elevation of OEF. CVRC caused by acetazolamide might reflect CO 2 reactivity. Significant improvement of CBF and CVRC, and normalization of OEF were observed after the operation. Also, significant improvement of neuropsychological function was observed by HDS-R and WAIS-R. Disturbance in neuropsychological function might reflect elevation of OEF. (author)

STATISTICAL ANALYSIS OF DAMAGEABILITY OF THE BYPASS ENGINES COMPRESSOR BLADES

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Boris A. Chichkov

2018-01-01

Full Text Available Aircraft gas turbine engines during the operation are exposed to damage of flowing parts. The elements of the engine design, appreciably determining operational characteristics are rotor blades. Character of typical damages for various types of engines depends on appointment and a geographical place of the aircraft operation on which one or another engine is installed. For example, the greatest problem for turboshaft engines operated in the dusty air conditions is erosive wear of a rotor blade airfoil. Among principal causes of flowing parts damages of bypass engine compressors are foreign object damages. Independently there are the damages caused by fatigue of a rotor blade material at dangerous blade mode. Pieces of the ice formed in the input unit, birds and the like can also be a source of danger. The foreign objects getting into the engine from runway are nuts, bolts, pieces of tire protectors, lock-wire, elements from earlier flying off aircraft, etc. The entry of foreign objects into the engine depends on both an operation mode (during the operation on the ground, on takeoff, on landing roll using the reverse and so on, and the aircraft engine position.Thus the foreign objects entered into the flowing path of bypass engine damage blade cascade of low and high pressure. Foreign objects entered into the flowing part of the engine with rotor blades result in dents on edges and blade shroud, deformations of edges, breakage, camber of peripheral parts and are distributed "nonlinear" on path length (steps. The article presents the results of the statistical analysis of three types engine compressors damageability over the period of more than three years. Damages are divided according to types of engines in whole and to their separate steps, depths and lengths, blades damage location. The results of the analysis make it possible to develop recommendations to carry out the optical-visual control procedures.

Ketamine has no effect on oxygenation indices following elective coronary artery bypass grafting under cardiopulmonary bypass

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Parthasarathi Gayatri

2011-01-01

Full Text Available Cardiopulmonary bypass is known to elicit systemic inflammatory response syndrome and organ dysfunction. This can result in pulmonary dysfunction and deterioration of oxygenation after cardiac surgery and cardiopulmonary bypass. Previous studies have reported varying results on anti-inflammatory strategies and oxygenation after cardiopulmonary bypass. Ketamine administered as a single dose at induction has been shown to reduce the pro-inflammatory serum markers in patients undergoing cardiopulmonary bypass. Therefore we investigated if ketamine can result in better oxygenation in these patients. This was a prospective randomized blinded study. Eighty consecutive adult patients undergoing elective coronary artery bypass grafting under cardiopulmonary bypass were included in the study. Patients were divided into two groups. Patients in ketamine group received 1mg/kg of ketamine intravenously at induction of anesthesia. Control group patients received an equal volume of saline. All patients received standard anesthesia, operative and postoperative care.Paired t test and independent sample t test were used to compare the inter-group and between group oxygenation indices respectively. Oxygenation index and duration of ventilation were analyzed. Deterioration of oxygenation index was noted in both the groups after cardiopulmonary bypass. However, there was no significant difference in the oxygenation index at various time points after cardiopulmonary bypass or the duration of ventilation between the two groups. This study shows that the administered as a single dose at induction does not result in better oxygenation after cardiopulmonary bypass.

Platelet hyperreactivity in response to on- and off-pump coronary artery bypass grafting

DEFF Research Database (Denmark)

Bochsen, Louise; Rosengaard, Lisbeth Bredahl; Nielsen, Allan Bybeck

2009-01-01

Hypercoagulability has been reported after off-pump coronary artery bypass grafting (OPCAB) compared with patients undergoing standard coronary artery bypass grafting (CABG) with cardiopulmonary bypass. The aim of this study was to evaluate the changes in platelet reactivity in response to cardiac...... and this study identified 23% of patients needing coronary bypass surgery to be at high risk for recurrent ischemic events at 1 month after surgery, based on the MA. These results suggest that a more aggressive antithrombotic treatment might be warranted for patients undergoing coronary artery bypass grafting...

Various clinical scenarios leading to development of the string sign of the internal thoracic artery after coronary bypass surgery: the role of competitive flow, a case series

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Kolozsvari Rudolf

2012-01-01

Full Text Available Abstract Background The left internal mammary artery (LIMA is the choice for grafting of the left anterior descending coronary artery (LAD. One possible mechanism of the rare graft failure involve the presence of competitive flow. Method 105 patients who had undergone coronary bypass grafting between 1998 and 2000 were included in this observational study. The recatheterizations were performed 28 months after the operations. The rate of patency the LIMA grafts was determined, and the cases with graft failure were analyzed. Results The LIMA graft was patent in 99 patients (94%. Six patients (6% exhibited diffuse involution of the graft (string sign. The string sign was always associated with competitive flow as the basis of the LIMA graft involution. In one case quantitative re-evaluation of the preoperative coronary angiography revealed merely less than 50% diameter stenosis on the LAD with a nonligated side-branch of the LIMA. At recatheterization in two patients the pressure wire measurements demonstrated only a non-significant decrease of the fractional flow reserve (0.83 and 0.89, despite the 53% and 57% diameter stenosis in the angiogram. Another patient displayeda significant regression of the LAD lesion between the pre- and postoperative coronary angiography (from 76% to 44% as the cause of the development of the competitive flow. In one instance, a radial artery graft on the LAD during a redo bypass operation resulted in competitive flow in the radial graft due to the greater diameter than that of the LIMA. In a further patient, competitive flow developed from a short sequential part of the LIMA graft between the nonsignificantly stenosed diagonal branch and the LAD, with involution of the main part of the graft to the diagonal branch. Conclusions The most common cause of the development of the string sign of a LIMA graft due to competitive flow is overassessment of the lesion of the LAD. Regression of a previous lesion or some other

Concomitant coronary artery revascularization and right pneumonectomy without cardiopulmonary bypass

NARCIS (Netherlands)

Hensens, AG; Zeebregts, C.J.A.M.; Liem, TH; Gehlmann, H; Lacquet, LK

Combined coronary artery bypass grafting (CABG) and pneumonectomy has a high morbidity and mortality rate, especially when the right lung has to be removed. A patient is described who underwent a CABG operation through a midline sternotomy without the use of cardiopulmonary bypass (CPB), and a right

Mini-cardiopulmonary bypass impact on blood conservation strategy in coronary artery bypass grafting.

Science.gov (United States)

Abdel Aal, Mohamed; ElNahal, Nezar; Bakir, Bakir Moustafa; Fouda, Mohamed

2011-04-01

Cardiopulmonary bypass (CPB) using a closed circuit system with minimal priming volume can be a solution to ameliorate adverse effects of CPB. We hypothesize that the use of mini-bypass in routine coronary artery bypass grafting (CABG) reduces homologous blood product use and postoperative bleeding. The study is designed to determine the differences in blood loss and transfusion requirements associated with a minimized CPB circuit vs. a standard bypass circuit. From February 2009 to August 2009, 80 patients were prospectively randomized to undergo elective CABG. Group A included 40 patients who had the minimized bypass circuit (Medtronic Resting Heart Circuit). Group B had an equal number of patients who had the standard CPB circuit (Stockert III, SEC.BM). Laboratory parameters for hemoglobin, hematocrit and platelet count were measured at baseline after initiation of CPB and after bypass. Blood usage was controlled by study-specific protocol (transfusion for hemoglobin platelets (1.95±2.95 units vs. 3.23±2.85), and postoperative drainage in 24 hours (531.62±220.12 ml vs. 729±294.9 ml, P<0.05). The hematocrit was 33±5% in group A, and 27±1% in group B. There was statistical differences seen in the mean hemoglobin level which was 10.19±0.65 g/dl in group A, and 9.4±0.68 g/dl in group B. There was statistical difference in the duration of ventilation, length of ICU stay. The requirement of inotropic support was lower in group A. The adoption of mini-bypass significantly reduces morbidity including donor blood usage and postoperative bleeding in routine CABG patients.

Skeletonization of Left Internal Mammary Artery in Coronary Artery Bypass Grafting

International Nuclear Information System (INIS)

Chaudhri, M.S.; Shah, M.U.A.; Asghar, M.I.; Janjua, A.M.; Iqbal, A.; Siddiqi, R.

2016-01-01

Objective: To compare mean per-operative flow capacity between skeletonized and pedicled left internal mammary artery (LIMA) in patients undergoing coronary artery bypass grafting (CABG) surgery. Study Design: Randomized control trial. Place and Duration of Study: Department of Cardiac Surgery, Armed Forces Institute of Cardiology and National Institute of Heart Diseases (AFIC-NIHD), Rawalpindi, Pakistan from February to August, 2013. Methodology: Patients undergoing CABG for coronary artery disease, under 80 years, excluded by the exclusion criteria; and fulfilling the inclusion criteria were randomly assigned to two groups of 70 each. One group underwent skeletonized and the other underwent pedicled technique of LIMA harvesting. Free flow was checked just before anastamosis of each LIMA to the LAD, manually in blood flow in ml per minute during cardiopulmonary bypass by allowing it to bleed into a 100 ml container over 20 seconds. A specialized proforma was used to record the age, gender, weight, disease, type of IMA used, and free flow of the IMA. Data was analyzed using SPSS 18. Result: The mean age of the patients was 57.16 years in 40 patients, ranging from 36 to 75 years. Disease pattern analysis showed 5 percent, 10.7 percent and 84.3 percent single, double and triple vessel coronary artery disease, respectively. There was significantly higher free flow in the skeletonized group than the pedicled group (p=0.04). Conclusion: Skeletonized IMA had superior flow to pedicled IMA in addition to its traditional proven advantages, which justifies its further use as a conduit for myocardial revascularization. (author)

In vitro effect of hemodilution on activated clotting time and high-dose thrombin time during cardiopulmonary bypass

NARCIS (Netherlands)

Huyzen, RJ; vanOeveren, W; Wei, FY; Stellingwerf, P; Boonstra, PW; Gu, YJ

Background. Extreme dilution of clotting factors, as may occur during pediatric or neonatal cardiopulmonary bypass, often leads to inadequate monitoring of anticoagulation with activated dotting time (ACT). In this study we postulate that the high-dose thrombin time (HiTT) is less influenced by

Modeling of the heat transfer in bypass transitional boundary-layer flows

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Simon, Frederick F.; Stephens, Craig A.

1991-01-01

A low Reynolds number k-epsilon turbulence model and conditioned momentum, energy and turbulence equations were used to predict bypass transition heat transfer on a flat plate in a high-disturbance environment with zero pressure gradient. The use of conditioned equations was demonstrated to be an improvement over the use of the global-time-averaged equations for the calculation of velocity profiles and turbulence intensity profiles in the transition region of a boundary layer. The approach of conditioned equations is extended to include heat transfer and a modeling of transition events is used to predict transition onset and the extent of transition on a flat plate. The events, which describe the boundary layer at the leading edge, result in boundary-layer regions consisting of: (1) the laminar, (2) pseudolaminar, (3) transitional, and (4) turbulent boundary layers. The modeled transition events were incorporated into the TEXSTAN 2-D boundary-layer code which is used to numerically predict the heat transfer. The numerical predictions in general compared well with the experimental data and revealed areas where additional experimental information is needed.

Indications and Outcomes of Prophylactic and Therapeutic Extracranial-to-intracranial Arterial Bypass for Cerebral Revascularization

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Emre Gazyakan, MD, MSc

2015-04-01

Conclusions: The collaboration of neurosurgeons and plastic surgeons in performing EC-IC bypass can result in excellent outcomes with a high bypass patency rate and few complications, particularly for prophylactic EC-IC bypass.

Ulinastatin Protects against Acute Kidney Injury in Infant Piglets Model Undergoing Surgery on Hypothermic Low-Flow Cardiopulmonary Bypass.

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Xiaocou Wang

Full Text Available Infants are more vulnerable to kidney injuries induced by inflammatory response syndrome and ischemia-reperfusion injury following cardiopulmonary bypass especially with prolonged hypothermic low-flow (HLF. This study aims to evaluate the protective role of ulinastatin, an anti-inflammatory agent, against acute kidney injuries in infant piglets model undergoing surgery on HLF cardiopulmonary bypass.Eighteen general-type infant piglets were randomly separated into the ulinastatin group (Group U, n = 6, the control group (Group C, n = 6, and the sham operation group (Group S, n = 6, and anaesthetized. The groups U and C received following experimental procedure: median thoracotomy, routine CPB and HLF, and finally weaned from CPB. The group S only underwent sham median thoracotomy. Ulinastatin at a dose of 5,000 units/kg body weight and a certain volume of saline were administrated to animals of the groups U and C at the beginning of CPB and at aortic declamping, respectively. Venous blood samples were collected at 3 different time points: after anesthesia induction in all experimental groups, 5 minutes, and 120 minutes after CPB in the Groups U and C. Markers for inflammation and acute kidney injury were tested in the collected plasma. N-acetyl-β-D-glucosaminidase (NAG from urine, markers of oxidative stress injury and TUNEL-positive cells in kidney tissues were also detected.The expressions of plasma inflammatory markers and acute kidney injury markers increased both in Group U and Group C at 5 min and 120 min after CPB. Also, numbers of TUNEL-positive cells and oxidative stress markers in kidney rose in both groups. At the time point of 120-min after CPB, compared with the Group C, some plasma inflammatory and acute kidney injury markers as well as TUNEL-positive cells and oxidative stress markers in kidney were significantly reduced in the Group U. Histologic analyses showed that HLF promoted acute tubular necrosis and dilatation

A study on the effects of the intake port configurations on the swirl flow generated in a small D.I. diesel engine

Science.gov (United States)

Kim, Yungjin; Han, Yongtaek; Lee, Kihyung

2014-06-01

This paper investigates the effect of intake port configuration on the swirl that is generated within a direct injection (D.I.) diesel engine. The in-cylinder flow characteristics are known to have significant effects on fuel-air mixing, combustion, and emissions. To clarify how to intensify the swirl flow, a swirl control valve (SCV) and a bypass were selected as design parameters for enhancing the swirl flow. The optimal intake port shape was also chosen as a parameter needed to efficiently generate a high swirl ratio. The results revealed that a key factor in generating a high swirl ratio was to control the intake airflow direction passing through the intake valve seat. Further, the swirl intensity was influenced by changing the distance between the helical and tangential ports, and the swirl flow was changed by the presence of a bypass near the intake valve seat. Additionally, the effect of intake port geometry on the in-cylinder flow field was investigated by using a laser sheet visualization method. The experimental results showed a correlation of swirl ratio and mass flow rate. In addition, we found that employing the bypass was an effective method to increase swirl ratio without sacrificing mass flow rate.

Hybrid Endovascular Aortic Aneurysm Repair: Preservation of Pelvic Perfusion with External to Internal Iliac Artery Bypass.

Science.gov (United States)

Mansukhani, Neel A; Havelka, George E; Helenowski, Irene B; Rodriguez, Heron E; Hoel, Andrew W; Eskandari, Mark K

2017-07-01

Diminished pelvic arterial flow as a result of intentional coverage/embolization of internal iliac arteries (IIA) during isolated endovascular common iliac artery aneurysm (CIAA) repair or endovascular repair of abdominal aortic aneurysms (EVAR) may result in symptomatic pelvic ischemia. Although generally well tolerated, in severe cases, pelvic ischemia may manifest as recalcitrant buttock claudication, vasculogenic impotence, or perineal, vesicle, rectal, and/or spinal cord ischemia. Branched graft technology has recently become available; however, many patients are not candidates for endovascular repair with these devices. Therefore, techniques to preserve pelvic arterial flow are needed. We reviewed our outcomes of isolated endovascular CIAA repair or EVAR in conjunction with unilateral external-internal iliac artery bypass. Single-center, retrospective review of 10 consecutive patients who underwent hybrid endovascular abdominal aortic aneurysm (AAA) or CIAA repair with concomitant external-internal iliac artery bypass between 2006 and 2015. Demographics, index procedural details, postoperative symptoms, hospital length of stay (LOS), follow-up imaging, and bypass patency were recorded. The cohort of 10 patients was all men with a mean age of 71 years (range: 56-84). Hybrid repair consisted of contralateral IIA coil embolization followed by EVAR with external iliac artery-internal iliac artery (EIA-IIA) bypass. All EIA-IIA bypasses were performed via a standard lower quadrant retroperitoneal approach with a prosthetic bypass graft. Technical success was 100%, and there were no perioperative deaths. One patient developed transient paraplegia, 1 patient had buttock claudication on the side of his hypogastric embolization contralateral to his iliac bypass, and 1 developed postoperative impotence. 20% of patients sustained long-term complications (buttock claudication and postoperative impotence). Mean LOS was 2.8 days (range: 1-9 days). Postoperative imaging

Repair of aortic arch aneurysm under cardiopulmonary bypass and deep hypothermia with low flow: A case report

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Md. Rezwanul Hoque

2016-07-01

Full Text Available Aortic arch surgery is the challenging and most difficult surgery among the cardiovascular operations. Cerebral and spinal complications are the most feared and common complications of aortic arch surgery. With best available techniques for cerebral and spinal protection, anesthetic management and good post-operative care; aortic arch surgery is considerably safer nowadays and satisfactory results can be achieved in most patients. Also, selecting the sites for arterial cannulation to maintain whole body circulation, during isolation of the aortic arch to operate on it, need proper anatomical description of the extent of the aneurysm. This is also achievable by the availability of the imaging techniques like Computed Tomog­raphy (CT with or without contrast, CT Angiography (CTA and Magnetic Resonance Imaging (MRI. We are reporting a case of aneurysm of aortic arch in a young adult, who had undergone repair under cardiopulmonary bypass and deep hypothermia with low flow and had normal convalescence without any cerebral or spinal complications.

Pulsatility index variations using two different transit-time flowmeters in coronary artery bypass surgery.

Science.gov (United States)

Nordgaard, Håvard B; Vitale, Nicola; Astudillo, Rafael; Renzulli, Attilio; Romundstad, Pål; Haaverstad, Rune

2010-05-01

Transit-time flow measurement is widely accepted as an intra-operative assessment in coronary artery bypass grafting (CABG). However, the two most commonly applied flowmeters, manufactured by MediStim ASA and Transonic Inc., have different default filter settings of 20 and 10 Hz, respectively. This may cause different flow measurements, which will influence the reported results. The aim was to compare pulsatility index (PI) values recorded by the MediStim and Transonic flowmeters in two different clinical settings: (1) analysis of the flow patterns recorded simultaneously by both flowmeters in the same CABGs; and (2) evaluation of flow patterns under different levels of filter settings in the same grafts. Graft flow and PI were measured using the two different flowmeters simultaneously in 19 bypass grafts. Finally, eight grafts were assessed under different digital filter settings at 5, 10, 20, 30, 50 and 100 Hz. The Transonic flowmeter provided substantially lower PI as compared with the MediStim flowmeter. By increasing the filter setting in the flowmeter, PI increased considerably. The Transonic flowmeter displayed a lower PI than the MediStim, due to a lower filter setting. In the Transonic,flow signals are filtered at a lower level, rendering a 'smoother' pattern of flow curves. Because different filter settings determine different PIs, caution must be taken when flow values and flowmeters are compared. The type of flowmeter should be indicated whenever graft flow measurements and derived indexes are provided [corrected]. Copyright 2009 European Association for Cardio-Thoracic Surgery. All rights reserved.

Perfusion Pressure Cerebral Infarct (PPCI) trial - the importance of mean arterial pressure during cardiopulmonary bypass to prevent cerebral complications after cardiac surgery

DEFF Research Database (Denmark)

Vedel, Anne G.; Holmgaard, Frederik; Rasmussen, Lars Simon

2016-01-01

Background: Debilitating brain injury occurs in 1.6–5 % of patients undergoing cardiac surgery with cardiopulmonary bypass. Diffusion-weighted magnetic resonance imaging studies have reported stroke-like lesions in up to 51 % of patients after cardiac surgery. The majority of the lesions seem...... to be caused by emboli, but inadequate blood flow caused by other mechanisms may increase ischaemia in the penumbra or cause watershed infarcts. During cardiopulmonary bypass, blood pressure can be below the lower limit of cerebral autoregulation. Although much debated, the constant blood flow provided...... by the cardiopulmonary bypass system is still considered by many as appropriate to avoid cerebral ischaemia despite the low blood pressure. Methods/design: The Perfusion Pressure Cerebral Infarct trial is a single-centre superiority trial with a blinded outcome assessment. The trial is randomising 210 patients...

Exhaust bypass flow control for exhaust heat recovery

Science.gov (United States)

Reynolds, Michael G.

2015-09-22

An exhaust system for an engine comprises an exhaust heat recovery apparatus configured to receive exhaust gas from the engine and comprises a first flow passage in fluid communication with the exhaust gas and a second flow passage in fluid communication with the exhaust gas. A heat exchanger/energy recovery unit is disposed in the second flow passage and has a working fluid circulating therethrough for exchange of heat from the exhaust gas to the working fluid. A control valve is disposed downstream of the first and the second flow passages in a low temperature region of the exhaust heat recovery apparatus to direct exhaust gas through the first flow passage or the second flow passage.

[Simplified laparoscopic gastric bypass. Initial experience].

Science.gov (United States)

Hernández-Miguelena, Luis; Maldonado-Vázquez, Angélica; Cortes-Romano, Pablo; Ríos-Cruz, Daniel; Marín-Domínguez, Raúl; Castillo-González, Armando

2014-01-01

Obesity surgery includes various gastrointestinal procedures. Roux-en-Y gastric bypass is the prototype of mixed procedures being the most practiced worldwide. A similar and novel technique has been adopted by Dr. Almino Cardoso Ramos and Dr. Manoel Galvao called "simplified bypass," which has been accepted due to the greater ease and very similar results to the conventional technique. The aim of this study is to describe the results of the simplified gastric bypass for treatment of morbid obesity in our institution. We performed a descriptive, retrospective study of all patients undergoing simplified gastric bypass from January 2008 to July 2012 in the obesity clinic of a private hospital in Mexico City. A total of 90 patients diagnosed with morbid obesity underwent simplified gastric bypass. Complications occurred in 10% of patients; these were more frequent bleeding and internal hernia. Mortality in the study period was 0%. The average weight loss at 12 months was 72.7%. Simplified gastric bypass surgery is safe with good mid-term results and a loss of adequate weight in 71% of cases.

A numerical comparison between the multiple-scales and finite-element solution for sound propagation in lined flow ducts

NARCIS (Netherlands)

Rienstra, S.W.; Eversman, W.

2001-01-01

An explicit, analytical, multiple-scales solution for modal sound transmission through slowly varying ducts with mean flow and acoustic lining is tested against a numerical finite-element solution solving the same potential flow equations. The test geometry taken is representative of a high-bypass

Target vessel detection by epicardial ultrasound in off-pump coronary bypass surgery.

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Hayakawa, Masato; Asai, Tohru; Kinoshita, Takeshi; Suzuki, Tomoaki; Shiraishi, Shoichiro

2013-01-01

The detection of embedded coronary arteries is difficult especially in off-pump coronary bypass surgery. From June 2010, we introduced high-frequency epicardial ultrasound (ECUS) to assess and evaluate embedded arteries during off-pump coronary bypass surgery. Between June 2010 and June 2011, a total of 89 consecutive patients underwent isolated coronary bypass surgery at our institution. The patients consisted of 72 men and 17 women with a mean age of 67.9 years. We routinely use the VeriQC system (MediStim, Oslo, Norway) to detect the target vessels in the operation. The patients were assigned to one of two groups, depending on whether ECUS was used in the operation (n = 10, ECUS group) or not (n = 79, non-ECUS group). We analyzed the impact of introducing the ECUS in terms of operative outcome. All patients underwent revascularization using the off-pump technique without emergent conversion to cardiopulmonary bypass during surgery. The total number of distal anastomoses was 299, and 12 target vessels could not be identified either visually or on palpation. Thus, the frequency of the embedded coronary arteries was 4.01% (12/299 cases). The preoperative profiles of the two groups were not significantly different. Operation time was significantly longer in the ECUS group (P = 0.02). There were no significant differences in postoperative outcome between the two groups. In the present study, in which the target coronary arteries could not be detected either visually or on palpation in 12 (4.01%) of 299 cases, the use of high-frequency ECUS allowed all patients to undergo off-pump coronary bypass surgery without conversion to cardiopulmonary bypass during the operation. High-frequency ECUS is therefore useful in off-pump coronary bypass surgery.

Sequential Vein Bypass Grafting is Not Associated with an Increase of Either In-hospital or Mid-term Adverse Events in Off-pump Coronary Artery Bypass Grafting

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Fucheng Xiao

2015-01-01

Full Text Available Background: The impact of sequential vein bypass grafting on clinical outcomes is less known in off-pump coronary artery bypass grafting (CABG. We aimed to evaluate the effects of sequential vein bypass grafting on clinical outcomes in off-pump CABG. Methods: From October 2009 to September 2013 at the Fuwai Hospital, 127 patients with at least one sequential venous graft were matched with 127 patients of individual venous grafts only, using propensity score matching method to obtain risk-adjusted outcome comparison. In-hospital measurement was composite outcome of in-hospital death, myocardial infarction (MI, stroke, requirement for intra-aortic ballon pump (IABP assistance and prolonged ventilation. Major adverse cardiac events (MACEs: Death, MI or repeat revascularization and angina recurrence were considered as mid-term endpoints. Results: No significant difference was observed among the groups in baseline characteristics. Intraoperative mean blood flow per vein graft was 40.4 ml in individual venous grafts groups versus 59.5 ml in sequential venous grafts groups (P < 0.001. There were no differences between individual and sequential venous grafts groups with regard to composite outcome of in-hospital mortality, MI, stroke, IABP assistance and prolonged ventilation (11.0% vs. 14.2%, P = 0.45. Individual in-hospital measurement also did not differ significantly between the two groups. At about four years follow-up, the survival estimates free from MACEs (92.5% vs. 97.3%, P = 0.36 and survival rates free of angina recurrence (80.9% vs. 85.5%, P = 0.48 were similar among individual and sequential venous grafts groups with a mean follow-up of 22.5 months. In the Cox regression analysis, sequential vein bypass grafting was not identified as an independent predictor of both MACEs and angina recurrence. Conclusions: Compared to individual vein bypass grafting, sequential vein bypass grafting was not associated with an increase of either in

High glycemic variability assessed by continuous glucose monitoring after surgical treatment of obesity by gastric bypass.

Science.gov (United States)

Hanaire, Helene; Bertrand, Monelle; Guerci, Bruno; Anduze, Yves; Guillaume, Eric; Ritz, Patrick

2011-06-01

Obesity surgery elicits complex changes in glucose metabolism that are difficult to observe with discontinuous glucose measurements. We aimed to evaluate glucose variability after gastric bypass by continuous glucose monitoring (CGM) in a real-life setting. CGM was performed for 4.2 ± 1.3 days in three groups of 10 subjects each: patients who had undergone gastric bypass and who were referred for postprandial symptoms compatible with mild hypoglycemia, nonoperated diabetes controls, and healthy controls. The maximum interstitial glucose (IG), SD of IG values, and mean amplitude of glucose excursions (MAGE) were significantly higher in operated patients and in diabetes controls than in healthy controls. The time to the postprandial peak IG was significantly shorter in operated patients (42.8 ± 6.0 min) than in diabetes controls (82.2 ± 11.1 min, P = 0.0002), as were the rates of glucose increase to the peak (2.4 ± 1.6 vs. 1.2 ± 0.3 mg/mL/min; P = 0.041). True hypoglycemia (glucose fasting state and 2 h postmeal. Glucose variability is exaggerated after gastric bypass, combining unusually high and early hyperglycemic peaks and rapid IG decreases. This might account for postprandial symptoms mimicking hypoglycemia but often seen without true hypoglycemia. Early postprandial hyperglycemia might be underestimated if glucose measurements are done 2 h postmeal.

Evaluation of juvenile salmonid bypass facilities and passage at water diversions on the lower Umatilla River. Final report

International Nuclear Information System (INIS)

Cameron, W.A.; Knapp, S.M.; Carmichael, R.W.

1997-07-01

Outdated juvenile and adult fish passage facilities were recently reconstructed at the five major irrigation dams on the lower Umatilla River, Oregon to meet National marine Fisheries Service (NMFS) design standards. Changes in design at juvenile fish bypass facilities included reduced mesh size on the rotating drum screens, larger screening area, a more oblique orientation of the drum screens to canal flow, improved screen seals, replacement of bypass portals with vertical slot bypass channels, and increased bypass pipe diameters. Weir-and-pool adult fish ladders and jump pools were replaced with vertical-slot ladders. From 1991--1995, they investigated injury and travel rate of juvenile fish moving through the facilities, and efficiency of screens in preventing fish entry into the canals. Water velocities in front of canal screens, at bypass channel entrances, and at ladder diffusers were measured to assess adherence to NMFS criteria and identify hydraulic patterns. Biological evaluations were conducted by releasing and recapturing marked yearling summer steelhead (Oncorhynchus mykiss), yearling spring chinook salmon (O. tshawytscha), and subyearling fall chinook salmon (O. tshawytscha) in varying locations within the fish passage facilities

Haemodynamics in axillobifemoral bypass grafts

NARCIS (Netherlands)

C.H. Wittens

1992-01-01

textabstractThis thesis is based on four publications on the subject of graft configuration and haemodynamics in axillobifemoral bypass grafts: 1. A clinical evaluation of 17 patients with axillobifemoral bypass graft operations, performed for various indications. Two important observations were

Milrinone, a phosphodiesterase III inhibitor, prevents reduction of jugular bulb saturation during rewarming from hypothermic cardiopulmonary bypass.

Science.gov (United States)

Iritakenishi, T; Hayashi, Y; Yamanaka, H; Kamibayashi, T; Ueda, K; Mashimo, T

2012-01-01

Inadequate cerebral oxygen balance during cardiopulmonary bypass may cause neuropsychological dysfunction. Milrinone, a phosphodiesterase III inhibitor, augments cerebral blood flow by direct vasodilatation. We conducted a prospective, randomized study in patients undergoing cardiac surgery with cardiopulmonary bypass to clarify the clinical efficacy of milrinone in the imbalance of cerebral oxygen supply and demand during the rewarming period of cardiopulmonary bypass. This is a prospective, randomized and placebo-controlled study. After anesthesia, a 5.5 F fiberoptic oximeter catheter was inserted into the right jugular bulb retrogradely for monitoring the jugular venous oxyhemoglobin saturation (SjO(2)). Patients were randomly assigned to two groups, one receiving a continuous infusion of milrinone, 0.5 µg/kg/min during hypothermic cardiopulmonary bypass, and the other receiving saline as control. Milrinone significantly prevented the reduction of the jugular venous oxyhemoglobin saturation at 10 minutes from the start of rewarming compared with the control group, but did not do so from 10 to 20 minutes after rewarming. Milrinone suppresses the reduction of SjO(2) and improves the balance of cerebral oxygen supply and demand during the early rewarming period of hypothermic cardiopulmonary bypass.

New technology increases perioperative haemoglobin levels for paediatric cardiopulmonary bypass: what is the benefit?

Science.gov (United States)

Thuys, Clarke; Horton, Stephen; Bennett, Martin; Augustin, Simon

2006-01-01

Increasing perioperative haemoglobin level by reducing priming volume and maintaining a safe cardiopulmonary bypass (CPB) system is the aim of every perfusionist. In this study, we have compared the two membrane oxygenators and pump systems used for paediatric bypass at the Royal Children's Hospital on a regular basis since 1988. We looked at all patients who had the Cobe VPCML (Cobe Laboratories, Denver, CO, USA) and Terumo RX-05 (Terumo Corporation, Tokyo, Japan) oxygenators used for flows from 800 mL/min up to the maximum rated flow for the respective oxygenator from January 2002 until March 2004. The VPCML refers to using only the 0.4-m2 section of the oxygenator. The pump systems used were the Stöckert CAPS (Stöckert Instrumente GmbH, Munich, Germany) and Jostra HL 30 (Jostra AB, Lund, Sweden). Changing from the VPCML to the RX-05 resulted in a 37% reduction in priming volume. The introduction of the Jostra HL 30 with a custom-designed mast system reduced the priming volume by another 15%. This change in priming volume allowed a significant increase, from 6 to 34%, in the percentage of patients who received bloodless primes, and for those patients who received blood primes, an increase in haemoglobin (Hb) on bypass from 8.2 to 9.6 g/dL, on average.

High-throughput enzyme screening platform for the IPP-bypass mevalonate pathway for isopentenol production

DEFF Research Database (Denmark)

Kang, Aram; Meadows, Corey W.; Canu, Nicolas

2017-01-01

Isopentenol (or isoprenol, 3-methyl-3-buten-1-ol) is a drop-in biofuel and a precursor for commodity chemicals such as isoprene. Biological production of isopentenol via the mevalonate pathway has been optimized extensively in Escherichia coli, yielding 70% of its theoretical maximum. However, high...... ATP requirements and isopentenyl diphosphate (IPP) toxicity pose immediate challenges for engineering bacterial strains to overproduce commodities utilizing IPP as an intermediate. To overcome these limitations, we developed an “IPP-bypass� isopentenol pathway using the promiscuous activity...

Spiritual Bypass: A Preliminary Investigation

Science.gov (United States)

Cashwell, Craig S.; Glosoff, Harriet L.; Hammond, Cheree

2010-01-01

The phenomenon of spiritual bypass has received limited attention in the transpersonal psychology and counseling literature and has not been subjected to empirical inquiry. This study examines the phenomenon of spiritual bypass by considering how spirituality, mindfulness, alexithymia (emotional restrictiveness), and narcissism work together to…

Natural Product Screening Reveals Naphthoquinone Complex I Bypass Factors.

Directory of Open Access Journals (Sweden)

Scott B Vafai

Full Text Available Deficiency of mitochondrial complex I is encountered in both rare and common diseases, but we have limited therapeutic options to treat this lesion to the oxidative phosphorylation system (OXPHOS. Idebenone and menadione are redox-active molecules capable of rescuing OXPHOS activity by engaging complex I-independent pathways of entry, often referred to as "complex I bypass." In the present study, we created a cellular model of complex I deficiency by using CRISPR genome editing to knock out Ndufa9 in mouse myoblasts, and utilized this cell line to develop a high-throughput screening platform for novel complex I bypass factors. We screened a library of ~40,000 natural product extracts and performed bioassay-guided fractionation on a subset of the top scoring hits. We isolated four plant-derived 1,4-naphthoquinone complex I bypass factors with structural similarity to menadione: chimaphilin and 3-chloro-chimaphilin from Chimaphila umbellata and dehydro-α-lapachone and dehydroiso-α-lapachone from Stereospermum euphoroides. We also tested a small number of structurally related naphthoquinones from commercial sources and identified two additional compounds with complex I bypass activity: 2-methoxy-1,4-naphthoquinone and 2-methoxy-3-methyl-1,4,-naphthoquinone. The six novel complex I bypass factors reported here expand this class of molecules and will be useful as tool compounds for investigating complex I disease biology.

Annular MHD Physics for Turbojet Energy Bypass

Science.gov (United States)

Schneider, Steven J.

2011-01-01

The use of annular Hall type MHD generator/accelerator ducts for turbojet energy bypass is evaluated assuming weakly ionized flows obtained from pulsed nanosecond discharges. The equations for a 1-D, axisymmetric MHD generator/accelerator are derived and numerically integrated to determine the generator/accelerator performance characteristics. The concept offers a shockless means of interacting with high speed inlet flows and potentially offers variable inlet geometry performance without the complexity of moving parts simply by varying the generator loading parameter. The cycle analysis conducted iteratively with a spike inlet and turbojet flying at M = 7 at 30 km altitude is estimated to have a positive thrust per unit mass flow of 185 N-s/kg. The turbojet allowable combustor temperature is set at an aggressive 2200 deg K. The annular MHD Hall generator/accelerator is L = 3 m in length with a B(sub r) = 5 Tesla magnetic field and a conductivity of sigma = 5 mho/m for the generator and sigma= 1.0 mho/m for the accelerator. The calculated isentropic efficiency for the generator is eta(sub sg) = 84 percent at an enthalpy extraction ratio, eta(sub Ng) = 0.63. The calculated isentropic efficiency for the accelerator is eta(sub sa) = 81 percent at an enthalpy addition ratio, eta(sub Na) = 0.62. An assessment of the ionization fraction necessary to achieve a conductivity of sigma = 1.0 mho/m is n(sub e)/n = 1.90 X 10(exp -6), and for sigma = 5.0 mho/m is n(sub e)/n = 9.52 X 10(exp -6).

Collins' bypass for the main ring

International Nuclear Information System (INIS)

Ohnuma, S.

1982-01-01

Design of the bypass for the main ring at Fermilab is discussed. Specific design features discussed include space, path length, geometric closure, matching of betatron functions, and external dispersion. Bypass parameters are given

Heart bypass surgery - minimally invasive - discharge

Science.gov (United States)

... invasive direct coronary artery bypass - discharge; MIDCAB - discharge; Robot assisted coronary artery bypass - discharge; RACAB - discharge; Keyhole ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

Analytical and computational investigations of a magnetohydrodynamics (MHD) energy-bypass system for supersonic gas turbine engines to enable hypersonic flight

Science.gov (United States)

Benyo, Theresa Louise

Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the

A study of ECC water bypass reduction technology for an improvement of core cooling capability

International Nuclear Information System (INIS)

Song, C. G.; Kwon, T. S.; Yun, B. J.

2006-02-01

The research for the reduction of ECC water bypass fraction was mainly performed to develop the flow mechanisms that ECC water can penetrate more effectively into a lower downcomer. Evaluation were carried out for the effect of major parameters on the bypass of ECC water in the downcomer with DVI. The following various physical models were derived for the reduction of the bypass fraction of ECC water: models of changing DVI injection angle, models of rearranging relative angles of DVI nozzles, model of grooved-and-subchannel type core barrel, model of dual core barrel. CFD analysis and MARS design verification were performed for the derived models as a first step performance estimation. Through out air-water verification experiments, quantitative evaluation were performed for each model, and three most efficient models were suggested. Examination were carried out for the requirement of structural modification and the change in structural integrity due to the adoption of one of the schemes

Exercise thallium-201 scintigraphy in evaluating aortocoronary bypass surgery

International Nuclear Information System (INIS)

Iskandrian, A.S.; Haaz, W.; Segal, B.L.; Kane, S.A.

1981-01-01

Thirty patients with recurrent symptoms after aortocoronary bypass graft surgery underwent angiography as well as exercise thallium 201 imaging. Exercise imaging has been shown to be highly specific (100 percent in our study) in evaluating patients after bypass surgery. Patients with complete revascularization have normal thallium 201 images. Similarly, exercise-induced defects are seen only in the presence of incomplete revascularization. There are patients, however, with incomplete revascularization with normal exercise images, but these generally limited to the right coronary artery or the diagonal vessels or their grafts

Dynamic Cerebral Autoregulation after Cardiopulmonary Bypass

DEFF Research Database (Denmark)

Christiansen, Claus Behrend; Berg, Ronan M G; Plovsing, Ronni R

2016-01-01

Background Cerebral hemodynamic disturbances in the peri- or postoperative period may contribute to postoperative cognitive dysfunction (POCD) in patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). We therefore examined dynamic cerebral autoregulation (d...

An Installation of IPS Bypass Line at the Fuel Test Loop

Energy Technology Data Exchange (ETDEWEB)

Choi, Ho Young; Ahn, G. H.; Lee, M.; Kim, M. S.; Cho, S. H.; Han, J. S.; Hur, S. O. [KAERI, Daejeon (Korea, Republic of)

2010-12-15

The Fuel Test Loop(FTL) was installed for the national goal of self-supporting technology in the field of design and construction of nuclear power plant. The FTL with the fuel irradiation equipment is essential in developing, improving and inspecting the fuel of CANDU type or PWR type nuclear power plant. The FTL should be operated at the same conditions of commercial nuclear power plant such as temperature, pressure, flow rate, neutron flux and so on. Starting designing in December 2001, the FTL was installed from March 2007 to August 2008. Especially the In Pile Section(IPS) was installed at IR1 hole in August 2008. Until September 2009 after loading the test fuel, a series of power escalation tests (LSD, CSB1, CSB2, HSB, HOP) were conducted. And it was operated at the condition of CSB2 for the 8 cycles from October 2009 to July 2010. But it could not be normally operated in early 2010, because the high radiation released from irradiated materials due to the worn down bearing of main cooling pump. So, we removed the IPS and installed a newly designed IPS bypass line to prevent increasing high radiation. In this report we will present preliminary works, main works processes, devices of making work environments, a designing and manufacturing of IPS bypass line and a rack of IPS, installing know-hows, problems and solutions broke out during the work etc. We believe that our efforts to complete successful installing and operating of the FTL system will contribute for the efficient utilization of HANARO

Multi-slice CT angiography in evaluation of extracranial-intracranial bypass

Energy Technology Data Exchange (ETDEWEB)

Teksam, Mehmet E-mail: mehmetteksam@yahoo.com; McKinney, Alexander; Truwit, Charles L

2004-12-01

Multi-slice CT (MSCT) scanners provided significant improvement in vascular applications. In this study, our purpose was to determine the clinical utility of MSCTA in evaluation of extracranial-intracranial (EC-IC) bypass patency. Eleven (4 men and 7 women; mean age, 46 years; age range, 19-68 years) consecutive patients who underwent MSCTA and DSA after EC-IC bypass surgery were evaluated retrospectively. All patients underwent DSA within 3 weeks of MSCTA. The indications for EC-IC bypass were severe stenosis or occlusion of intracranial arteries in seven patients and therapeutic occlusion of intracranial artery for unclippable giant aneurysm in four patients. Ten patients underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and one patient underwent occipital artery-posterior cerebral artery (PCA) bypass. Eight STA-MCA bypasses in six patients were patent on MSCTA which were confirmed on DSA. Two MSCTA bypasses and one occipital artery-posterior cerebral artery (PCA) bypass were occluded in three patients on MSCTA and DSA. In one patient, minimal stenosis of the STA-MCA bypass was identified on MSCTA and DSA. In 1 patient, STA-MCA bypass was not well seen on MSCTA and suspected for occlusion. DSA identified the occlusion of bypass on this patient. MSCTA seems to be a very promising noninvasive technique in evaluation of EC-IC bypass.

Multi-slice CT angiography in evaluation of extracranial-intracranial bypass

International Nuclear Information System (INIS)

Teksam, Mehmet; McKinney, Alexander; Truwit, Charles L.

2004-01-01

Multi-slice CT (MSCT) scanners provided significant improvement in vascular applications. In this study, our purpose was to determine the clinical utility of MSCTA in evaluation of extracranial-intracranial (EC-IC) bypass patency. Eleven (4 men and 7 women; mean age, 46 years; age range, 19-68 years) consecutive patients who underwent MSCTA and DSA after EC-IC bypass surgery were evaluated retrospectively. All patients underwent DSA within 3 weeks of MSCTA. The indications for EC-IC bypass were severe stenosis or occlusion of intracranial arteries in seven patients and therapeutic occlusion of intracranial artery for unclippable giant aneurysm in four patients. Ten patients underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and one patient underwent occipital artery-posterior cerebral artery (PCA) bypass. Eight STA-MCA bypasses in six patients were patent on MSCTA which were confirmed on DSA. Two MSCTA bypasses and one occipital artery-posterior cerebral artery (PCA) bypass were occluded in three patients on MSCTA and DSA. In one patient, minimal stenosis of the STA-MCA bypass was identified on MSCTA and DSA. In 1 patient, STA-MCA bypass was not well seen on MSCTA and suspected for occlusion. DSA identified the occlusion of bypass on this patient. MSCTA seems to be a very promising noninvasive technique in evaluation of EC-IC bypass

Effective void fraction for a BWR assembly with boiling in the bypass region

International Nuclear Information System (INIS)

Galperin, A.; Segev, M.; Knoglinger, E.

1991-09-01

Average BWR assembly cross-sections for nominal conditions, namely for zero bypass void, can be utilised in the analysis of transient conditions with boiling in the bypass. A model is developed to yield an effective channel void for such conditions. The use of this void in conjunction with the 'nominal conditions' cross section library approximately preserves the assembly K-infinity corresponding to the true channel and bypass voids. The effective void is an augmentation of the actual channel void. The augment is proportional to the bypass-to-channel volume ratio, to the bypass void, and to a weight W which is introduced to quantify the fact that a water molecule in the bypass has a different assembly criticality worth than one in the channel. The formula developed is superior to the practice of choosing W=1, namely a simple, non-weighted, transfer of water from channel to bypass. The use of this approximate effective channel void reproduces actual K-infinity values of assemblies to better than 5 mk, whereas the use of a simple model sometimes misspredicts the assembly K-infinity by 40 mK. The effective void model cannot handle cases in which both channel and bypass void value are high, simply because then the effective void α ch eff becomes meaningless. A method to treat the α eff >1 domain is developed by which corrections to cross sections are provided. Such corrections are synthesised as functions of the assembly parameters. (author) figs., tabs., refs

High flow ceramic pot filters.

Science.gov (United States)

van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

2017-11-01

Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass pump tubing. 870.4390 Section 870.4390 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is...

21 CFR 870.4240 - Cardiopulmonary bypass heat exchanger.

Science.gov (United States)

2010-04-01

... bypass heat exchanger. (a) Identification. A cardiopulmonary bypass heat exchanger is a device, consisting of a heat exchange system used in extracorporeal circulation to warm or cool the blood or... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass heat exchanger. 870.4240...

Analysis of the force exercised in pipes by accumulation of water in the head stock of turbine bypass; Analisis de la fuerza ejercida en tuberias por acumulamiento de agua en el cabezal de baipas de turbina

Energy Technology Data Exchange (ETDEWEB)

Cecenas F, M.; Ovando C, R.; Campos G, R. M., E-mail: mcf@iie.org.mx [Instituto de Investigaciones Electricas, Reforma 113, Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)

2011-11-15

The head stock and valves of turbine bypass allow canalize the main vapor coming from the reactor toward the condenser, without carrying out work in the turbo-generator. In this work is assumed that is accumulates condensed in the head stock during a time period in which the bypass system does not operate. For operation maneuvers, the opening of the bypass is demanded, for what the accumulated water is suddenly dragged by the vapor to high pressure coming from the reactor toward the condenser, which operates to inferior pressures to the atmospheric. The generated flow produces a mechanical effort in the lines and its supports. By means of the RELAP5 code the bypass system is modeled, the discharge transitory to the condenser is simulated and the speeds of the mixture water/vapor are calculated. Processing the exit of RELAP5 the mechanical effort that is subjected the pipe is calculated, and the study is complemented with a sensibility analysis to the quantity of stored water in the volume of the bypass head stock. (Author)

Morphometric methods for simulation of water flow

NARCIS (Netherlands)

Booltink, H.W.G.

1993-01-01

Water flow in structured soils is strongly governed by the occurence of macropores. In this study emphasis was given to combined research of morphology of water- conducting macropores and soil physical measurements on bypass flow. Main research objectives were to: (i) develop and improve

Post-Bypass Extensive Ascites due to Splanchnic Bypass and the Effectiveness of Hyperalimentation Treatment

Directory of Open Access Journals (Sweden)

Veysel Temizkan

2013-04-01

Full Text Available Reperfusion edema may develop in the early periods of chronic ischemic tissue reperfusion. Reperfusion edema may be represented after the splanchnic bypass with ascites, abdominal distension, and liver and kidney function impairment. In this article, we are reporting the hyperalimentation treatment and its results for the common ascites and hepatorenal syndrome, after a coeliac and superior mesenteric artery bypass. [Arch Clin Exp Surg 2013; 2(2.000: 124-128

Extra-intracranial standard bypass in the elderly

DEFF Research Database (Denmark)

Sandow, Nora; von Weitzel-Mudersbach, Paul; Rosenbaum, Sverre

2013-01-01

Patients with chronic atherosclerotic vessel occlusion and cerebrovascular hemodynamic insufficiency may benefit from extra-intracranial (EC-IC) bypass surgery. Due to demographic changes, an increasing number of elderly patients presents with cerebrovascular hemodynamic insufficiency. So far......, little data for EC-IC bypass surgery in elderly patients suffering occlusive cerebrovascular disease are available. We therefore designed a retrospective study to address the question whether EC-IC bypass is a safe and efficient treatment in a patient cohort ≥70 years....

Ventricular Septal Defect in an Octogenarian: A Case Report of VSD Surgical Repair Concomitant with Coronary Artery Bypass and Valvular Surgery

Directory of Open Access Journals (Sweden)

Eiki Tayama

2012-01-01

Full Text Available Finding an untreated or asymptomatic large ventricular septal defect (VSD in an elderly patient is uncommon. The present case was an 81-year-old man who suffered from acute myocardial infarction due to three-vessel coronary disease, mitral and tricuspid valve insufficiency, and high-flow perimembranous VSD (Qp/Qs 2.3. Although the patient was elderly and the VSD had been asymptomatic for a long time, we considered that high-flow VSD and valve diseases should be repaired simultaneously with coronary disease. Then, he underwent elective surgery, namely, VSD patch repair concomitant with coronary artery bypass grafting, and mitral and tricuspid annuloplasty. His postoperative course was uneventful. We conclude that, even for an octogenarian, surgical repair of VSD is recommendable, if surgical indications are appropriate.

21 CFR 870.4350 - Cardiopulmonary bypass oxygenator.

Science.gov (United States)

2010-04-01

... bypass oxygenator. (a) Identification. A cardiopulmonary bypass oxygenator is a device used to exchange gases between blood and a gaseous environment to satisfy the gas exchange needs of a patient during open...

The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

Science.gov (United States)

Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

2013-01-01

The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

Energy-efficient and cost-effective in-house substations bypass for improving thermal and DHW (domestic hot water) comfort in bathrooms in low-energy buildings supplied by low-temperature district heating

DEFF Research Database (Denmark)

Brand, Marek; Dalla Rosa, Alessandro; Svendsen, Svend

2014-01-01

temperature and additional cooling of bypass water by 3.9 °C, reducing the heat loss from the DH network by 13% and covering 40% of the heat used in the bathroom FH. The use of the bypass flow in bathroom FH is a cost-effective solution exploiting the heat that would otherwise be lost in the DH network......Using a bypass to redirect a small flow through the in-house DH (district heating) substation directly to the return pipe is a commonly used but energy-inefficient solution to keep the DH network “warm” during non-heating seasons. Instead, this water can be redirected to the bathroom FH (floor...... heating) to cool down further and thus reduce the heat lost from bypass operation while tempering the bathroom floor and guaranteeing fast provision of DHW (domestic hot water). We used the commercial software IDA-ICE to model a reference building where we implemented various solutions for controlling...

Variations in dietary intake after bypass surgery for obesity. Possible relation to development of fatty liver after jejunoileal bypass

International Nuclear Information System (INIS)

Rogus, J.; Blumenthal, S.A.

1981-01-01

Consumption of nutrients and food energy was compared, with concomitant chemical and radiologic measurements of hepatic fat content, preoperatively and postoperatively in 25 patients who underwent gastric or jejunoileal bypass for obesity. Patients in the two operative groups ingested similar quantities of food before surgery. After surgery, caloric intake from all sources decreased in both groups but to a significantly greater extent in the gastric bypass patients. During the first six months postoperatively, the 13 gastric bypass patients showed no changes in hepatic fat content, whereas substantial increases in liver fat uniformly occurred in the 12 patients who had jejunoileal bypasses. It is suggested that dietary carbohydrate may have contributed to the accretion of liver fat in these 12 patients

Aortic valve bypass surgery in severe aortic valve stenosis: Insights from cardiac and brain magnetic resonance imaging.

Science.gov (United States)

Mantini, Cesare; Caulo, Massimo; Marinelli, Daniele; Chiacchiaretta, Piero; Tartaro, Armando; Cotroneo, Antonio Raffaele; Di Giammarco, Gabriele

2018-04-13

To investigate and describe the distribution of aortic and cerebral blood flow (CBF) in patients with severe valvular aortic stenosis (AS) before and after aortic valve bypass (AVB) surgery. We enrolled 10 consecutive patients who underwent AVB surgery for severe AS. Cardiovascular magnetic resonance imaging (CMR) and brain magnetic resonance imaging were performed as baseline before surgery and twice after surgery. Quantitative flow measurements were obtained using 1.5-T magnetic resonance imaging (MRI) scanner phase-contrast images of the ascending aorta, descending thoracic aorta (3 cm proximally and distally from the conduit-to-aorta anastomosis), and ventricular outflow portion of the conduit. The evaluation of CBF was performed using 3.0-T MRI scanner arterial spin labeling (ASL) through sequences acquired at the gray matter, dorsal default-mode network, and sensorimotor levels. Conduit flow, expressed as the percentage of total antegrade flow through the conduit, was 63.5 ± 8% and 67.8 ± 7% on early and mid-term postoperative CMR, respectively (P surgery in patients with severe AS, cardiac output is split between the native left ventricular outflow tract and the apico-aortic bypass, with two-thirds of the total antegrade flow passing through the latter and one-third passing through the former. In our experience, CBF assessment confirms that the flow redistribution does not jeopardize cerebral blood supply. Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Pressure data for various flow channels in proton exchange membrane (PEM) fuel cell

International Nuclear Information System (INIS)

Cho, Son Ah; Lee, Pil Hyong; Han, Sang Seok; Hwang, Sang Soon

2008-01-01

Micro flow channels in flow plates of fuel cells have become much narrower and longer to improve reactant flow distribution leading to increase of pumping power. Therefore it is very important to minimize the pressure drops in the flow channel because increased pumping power reduces overall efficiency. We investigated pressure drops in a micro flow channel at the anode and cathode compared to pressure losses for cold flow in straight, bended and serpentine channels. The results show that friction factors for cold flow channels could be used for parallel and bended flow channel designs for fuel cells. Pressure drop in the serpentine flow channel is the lowest among all flow channels due to bypass flow across the gas diffusion layer under reactive flow condition, although its pressure drop is highest for a cold flow condition. So the effect of bypass flow for serpentine flow channels should be considered when designing flow channels

Measurements of regional cerebral blood flow (rCBF) using dynamic single-photon emission computed tomography (DSPECT): Definition of a generally acceptable normal range and follow-up checks after extracranial bypass surgery

International Nuclear Information System (INIS)

Kreisig, T.

1986-01-01

The usefulness of dynamic single-photon emission computed tomography was evaluated in 50 volunteers with unobtrusive cerebral findings, who were to provide the relevant standard values. It was found that the values measured were easily reproducible. Measurements in patients showing cerebrovascular disease that were carried out before and after extracranial bypass surgery did mostly not suggest any perceivable improvement of cerebral blood flow. In isolated cases the cerebral reserve was influenced favourably, as judged from measurements after administration of acetazolamide. (MBC) [de

Outcomes of lower extremity bypass performed for acute limb ischemia.

Science.gov (United States)

Baril, Donald T; Patel, Virendra I; Judelson, Dejah R; Goodney, Philip P; McPhee, James T; Hevelone, Nathanael D; Cronenwett, Jack L; Schanzer, Andres

2013-10-01

Acute limb ischemia remains one of the most challenging emergencies in vascular surgery. Historically, outcomes following interventions for acute limb ischemia have been associated with high rates of morbidity and mortality. The purpose of this study was to determine contemporary outcomes following lower extremity bypass performed for acute limb ischemia. All patients undergoing infrainguinal lower extremity bypass between 2003 and 2011 within hospitals comprising the Vascular Study Group of New England were identified. Patients were stratified according to whether or not the indication for lower extremity bypass was acute limb ischemia. Primary end points included bypass graft occlusion, major amputation, and mortality at 1 year postoperatively as determined by Kaplan-Meier life table analysis. Multivariable Cox proportional hazards models were constructed to evaluate independent predictors of mortality and major amputation at 1 year. Of 5712 lower extremity bypass procedures, 323 (5.7%) were performed for acute limb ischemia. Patients undergoing lower extremity bypass for acute limb ischemia were similar in age (66 vs 67; P = .084) and sex (68% male vs 69% male; P = .617) compared with chronic ischemia patients, but were less likely to be on aspirin (63% vs 75%; P < .0001) or a statin (55% vs 68%; P < .0001). Patients with acute limb ischemia were more likely to be current smokers (49% vs 39%; P < .0001), to have had a prior ipsilateral bypass (33% vs 24%; P = .004) or a prior ipsilateral percutaneous intervention (41% vs 29%; P = .001). Bypasses performed for acute limb ischemia were longer in duration (270 vs 244 minutes; P = .007), had greater blood loss (363 vs 272 mL; P < .0001), and more commonly utilized prosthetic conduits (41% vs 33%; P = .003). Acute limb ischemia patients experienced increased in-hospital major adverse events (20% vs 12%; P < .0001) including myocardial infarction, congestive heart failure exacerbation, deterioration in renal function

On-pump versus off-pump coronary artery bypass surgery

DEFF Research Database (Denmark)

Houlind, Kim Christian

2013-01-01

Off pump coronary artery bypass surgery has been purported to be safer than conventional coronary artery bypass surgery performed using cardiopulmonary bypass. This theory was supported by a number of early series, but failed to be confirmed by a number of small, randomized controlled trials...

Fourier Analysis of Peripheral Blood Pressure and Flow in Intraoperative Assessment of Infrainguinal Arterial Reconstructions

Directory of Open Access Journals (Sweden)

Cheshmedzhiev Mihail V.

2014-08-01

Full Text Available AIM: To assess infrainguinal arterial reconstructions by intraoperative flowmetry under the distal anastomosis using a fast Fourier transformation; calculate and compare the amplitude ratios of peripheral arterial blood pressure and volume flow before and after drug-induced vasodilation of occluded bypass grafts and bypass grafts that have been patent at least for 1 year. To find what magnitude of the change of these ratios indicate a long-term patency of the bypass grafting. PATIENTS AND METHODS: We compared the results of the intraoperative flowmetry tests of 97 patients with infrainguinal arterial reconstructions. The patients were divided into two groups based on the graft status: the grafts in 49 patients were patent for at least a year, and 48 patients had failed bypass. We used a fast Fourier transform (FFT of the pressure and blood flow waves and compared the ratios of their amplitudes before and after administration of a vasodilator drug into the graft. Comparing the ratios obtained before and those after administration of the drug we quantified their change in each group and analysed them. RESULTS: After a drug-induced vasodilation, the blood pressure and flow amplitude ratios for the group with compromised reconstructions were less than 1.9 times smaller than those before drug infusion, while for the group with bypass grafts that had been functional for at least 12 months the ratios declined by more than 1.9≈2 times. CONCLUSION: The magnitude of the change of amplitude ratios of the peripheral pressure and volume flow after drug-induced vasodilation can be used to make an assessment of the bypass graft and the distal arterial segment.

Flow mixing inside a control-rod guide tube – Experimental tests and CFD simulations

International Nuclear Information System (INIS)

Angele, Kristian; Odemark, Ylva; Cehlin, Mathias; Hemström, Bengt; Högström, Carl-Maikel; Henriksson, Mats; Tinoco, Hernan; Lindqvist, Hans

2011-01-01

This paper covers a combined experimental and computational effort carried out at Vattenfall Research and Development AB in order to study the thermal mixing in the annular region between a top tube and a control-rod stem. The low frequency thermal fluctuations in this region can result in problems with thermal fatigue and have caused cracks in the control-rod stems of several nuclear reactors (). The flow in the vertical annular region formed by the top tube and the control-rod stem is characterized by the mixing of hot bypass flow with cold crud-removal flow. The crud-removal flow is flowing upwards along the control-rod stem, and the warmer bypass flow is entering through eight horizontal holes positioned in the lower part of the guide tube and four holes in the upper part of the top tube, forming jets. Two full-scale models of a control rod, including the control-rod stem and the guide tube, were constructed. The first model, designed to work at atmospheric conditions, was made of Plexiglass, in order to be able to visualize the mixing process, whereas the second one was made of steel to allow for a higher temperature difference between the two flows, and the heating of the top tube. CFD simulations of the case at atmospheric conditions were also carried out. Both the experiments and the simulations showed that the mixing region between the cold crud-removal flow and the warm bypass flow is dominated by large flow structures coming from above. The process is characterized by low frequency, high amplitude temperature fluctuations. The process is basically hydrodynamic, caused by the downward transport of flow structures originated at the upper bypass inlets. The damping thermal effects through buoyancy is of secondary importance, as also the scaling analysis shows, however a slight damping of the temperature fluctuations can be seen due to natural convection due to a pre-heating of the cold crud-removal flow. The comparison between numerical and experimental

Integrated soft sensor model for flow control.

Science.gov (United States)

Aijälä, G; Lumley, D

2006-01-01

Tighter discharge permits often require wastewater treatment plants to maximize utilization of available facilities in order to cost-effectively reach these goals. Important aspects are minimizing internal disturbances and using available information in a smart way to improve plant performance. In this study, flow control throughout a large highly automated wastewater treatment plant (WWTP) was implemented in order to reduce internal disturbances and to provide a firm foundation for more advanced process control. A modular flow control system was constructed based on existing instrumentation and soft sensor flow models. Modules were constructed for every unit process in water treatment and integrated into a plant-wide model. The flow control system is used to automatically control recirculation flows and bypass flows at the plant. The system was also successful in making accurate flow estimations at points in the plant where it is not possible to have conventional flow meter instrumentation. The system provides fault detection for physical flow measuring devices. The module construction allows easy adaptation for new unit processes added to the treatment plant.

Computational modelling of flow and tip variations of aortic cannulae in cardiopulmonary bypass procedure

Science.gov (United States)

Thomas, Siti A.; Empaling, Shirly; Darlis, Nofrizalidris; Osman, Kahar; Dillon, Jeswant; Taib, Ishkrizat; Khudzari, Ahmad Zahran Md

2017-09-01

Aortic cannulation has been the gold standard for maintaining cardiovascular function during open heart surgery while being connected onto the heart lung machine. These cannulation produces high velocity outflow which may lead to adverse effect on patient condition, especially sandblasting effect on aorta wall and blood cells damage. This paper reports a novel design that was able to decrease high velocity outflow. There were three design factors of that was investigated. The design factors consist of the cannula type, the flow rate, and the cannula tip design which result in 12 variations. The cannulae type used were the spiral flow inducing cannula and the standard cannula. The flow rates are varied from three to five litres per minute (lpm). Parameters for each cannula variation included maximum velocity within the aorta, pressure drop, wall shear stress (WSS) area exceeding 15 Pa, and impinging velocity on the aorta wall were evaluated. Based on the result, spiral flow inducing cannulae is proposed as a better alternatives due to its ability to reduce outflow velocity. Meanwhile, the pressure drop of all variations are less than the limit of 100 mmHg, although standard cannulae yielded better result. All cannulae show low reading of wall shear stress which decrease the possibilities for atherogenesis formation. In conclusion, as far as velocity is concerned, spiral flow is better compared to standard flow across all cannulae variations.

[Coronary bypass in treatment of high-risk patients].

Science.gov (United States)

Avdagić, Harun; Mujanović, Emir; Mesanović, Nihad; Sijereić-Avdagić, Selma; Pirić, Melika

2009-01-01

Although it is possible to find a number of comparative studies in the world literature discussing the results of coronary artery bypass surgery (CABG) with and without cardiopulmonary bypass (CPB), until now such analysis has not been made in Bosnia and Herzegovina. The main aim of this scientific work was to compare morbidity and mortality, need for blood transfusions, length of stay in the intensive care unit, total length of hospitalisation and number of complication in two groups of patients operated with these methods. Patients with EuroScore > or =5 with CABG operated in Cardiovascular Clinic Tuzla, from May 2000 to May 2005 divided in two groups, were included in this study. There were 100 patients in the first group operated with CPB and 100 patients in the second group operated without CPB. The average time spent on respirators was shorter in patients operated without CPB (3.7 vs.9.74 hours, p = 0.023) and the time spent in Intensive care shorter too (19 vs. 23 days, p = 0.008). Volume of postoperative bleeding was less in patients operated without CPB (574.9 vs. 988.9 ml, p = 0.038), as volume after blood transfusion (168.8 vs. 350.3 mi, p = 0.001). Intraoperative inotrope support was less in patients operated without CPB (8.0 vs. 19.0%, p = 0.038) as postoperative inotrope support (6.0 vs. 17.0%, p = 0.027). The most usual postoperative complication was atrial fibrillation and there was no difference between patients operated with CPB and without CPB (24% vs. 17%, p = 0.293). Mortality was not different in patients operated with or without CPB (2.0% vs. 6.0%, p = 0.140). The average time of total hospitalisation was also shorter in patients operated without CPB (8.0 vs. 9.5 days, p = 0.039. In conclusion CABG without CPB has many advantages compared to the conventional method. Mortality and morbidity are reduced and there is less need for transfusion. The time spent on mechanical ventilation is reduced and less time is spent in intensive care. The total

Assessing Patient bypass Behavior Using Taxi Trip Origin–Destination (OD Data

Directory of Open Access Journals (Sweden)

Gege Yang

2016-09-01

Full Text Available Many patients prefer to use the best hospitals even if there are one or more other hospitals closer to their homes; this behavior is called “hospital bypass behavior”. Because this behavior can be problematic in urban areas, it is important that it be reduced. In this paper, the taxi GPS data of Beijing and Suzhou were used to measure hospital bypass behavior. The “bypass behavior index” (BBI represents the bypass behavior for each hospital. The results indicated that the mean hospital bypass trip distance value ranges from 5.988 km to 9.754 km in Beijing and from 4.168 km to 10.283 km in Suzhou. In general, the bypass shares of both areas show a gradually increasing trend. The following hospitals exhibited significant patient bypass behavior: the 301 Hospital, Beijing Children’s Hospital, the Second Affiliated Hospital of Soochow University and the Suzhou Hospital of Traditional Chinese Medicine. The hospitals’ reputation, transport accessibility and spatial distribution were found to be the main factors affecting patient bypass behavior. Although the hospital bypass phenomena generally appeared to be more pronounced in Beijing, the bypass trip distances between hospitals were found to be more significant in Suzhou.

Minnowbrook IV: 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows

Science.gov (United States)

LaGraff, John E. (Editor); Ashpis, David E.

2004-01-01

This Minnowbrook IV 2003 workshop on Transition and Unsteady Aspects of Turbomachinery Flows includes the following topics: 1) Current Issues in Unsteady Turbomachinery Flows; 2) Global Instability and Control of Low-Pressure Turbine Flows; 3) Influence of End Wall Leakage on Secondary Flow Development in Axial Turbines; 4) Active and Passive Flow Control on Low Pressure Turbine Airfoils; 5) Experimental and Numerical Investigation of Transitional Flows as Affected by Passing Wakes; 6) Effects of Freestream Turbulence on Turbine Blade Heat Transfer; 7) Bypass Transition Via Continuous Modes and Unsteady Effects on Film Cooling; 8) High Frequency Surface Heat Flux Imaging of Bypass Transition; 9) Skin Friction and Heat Flux Oscillations in Upstream Moving Wave Packets; 10) Transition Mechanisms and Use of Surface Roughness to Enhance the Benefits of Wake Passing in LP Turbines; 11) Transient Growth Approach to Roughness-Induced Transition; 12) Roughness- and Freestream-Turbulence-Induced Transient Growth as a Bypass Transition Mechanism; 13) Receptivity Calculations as a Means to Predicting Transition; 14) On Streamwise Vortices in a Curved Wall Jet and Their Effect on the Mean Flow; 15) Plasma Actuators for Separation Control of Low Pressure Turbine Blades; 16) Boundary-Layer Separation Control Under Low-Pressure-Turbine Conditions Using Glow-Discharge Plasma Actuators; 17) Control of Separation for Low Pressure Turbine Blades: Numerical Simulation; 18) Effects of Elevated Free-Stream Turbulence on Active Control of a Separation Bubble; 19) Wakes, Calming and Transition Under Strong Adverse Pressure Gradients; 20) Transitional Bubble in Periodic Flow Phase Shift; 21) Modelling Spots: The Calmed Region, Pressure Gradient Effects and Background; 22) Modeling of Unsteady Transitional Flow on Axial Compressor Blades; 23) Challenges in Predicting Component Efficiencies in Turbomachines With Low Reynolds Number Blading; 24) Observations on the Causal Relationship Between

Dynamic Performance of High Bypass Ratio Turbine Engines With Water Ingestion

Science.gov (United States)

Murthy, S. N. B.

1996-01-01

The research on dynamic performance of high bypass turbofan engines includes studies on inlets, turbomachinery and the total engine system operating with air-water mixture; the water may be in vapor, droplet, or film form, and their combinations. Prediction codes (WISGS, WINCOF, WINCOF-1, WINCLR, and Transient Engine Performance Code) for performance changes, as well as changes in blade-casing clearance, have been established and demonstrated in application to actual, generic engines. In view of the continuous changes in water distribution in turbomachinery, the performance of both components and the total engine system must be determined in a time-dependent mode; hence, the determination of clearance changes also requires a time-dependent approach. In general, the performance and clearances changes cannot be scaled either with respect to operating or ingestion conditions. Removal of water prior to phase change is the most effective means of avoiding ingestion effects. Sufficient background has been established to perform definitive, full scale tests on a set of components and a complete engine to establish engine control and operability with various air-water vapor-water mixtures.

Small Intestinal Bypass Induces a Persistent Weight-Loss Effect and Improves Glucose Tolerance in Obese Rats.

Science.gov (United States)

Cao, Jiaqing; Ren, Quan; Tan, Cai; Duan, Jinyuan

2017-07-01

This study investigated the role of proximal small intestinal bypass (PSIB) and distal small intestinal bypass (DSIB) as well as their long-term effects on weight loss and glucose metabolism in high-sugar and high-fat diet-induced obese rats. Sprague-Dawley rats were divided into four groups: PSIB, bypassing 60% of the proximal small intestine length; DSIB, bypassing 60% of the distal small intestine length; sham-operated (Sham) animals; and control animals. All rats were fed a high-sugar and high-fat diet after surgery. The primary outcome measures were body weight, food intake, fasting blood glucose (FBG) levels, oral glucose tolerance test (OGTT), and the insulin tolerance test (ITT). Global body weight (BW) and food intake in the PSIB and DSIB groups were lower than those in the Sham group at postoperative week 2. BW and food intake in the PSIB group were lower than those in the DSIB group at postoperative week 24. The PSIB and DSIB groups exhibited improvement in glucose tolerance at postoperative weeks 4, 8, and 24. The PSIB and DSIB groups exhibited improvement in FBG at postoperative week 24, and only the DSIB group exhibited improvement in insulin sensitivity. This study provides experimental evidence that PSIB surgery induced a better and more persistent weight loss effect than DSIB surgery and that the two types of intestinal bypass surgeries yielded equivalent and stable long-term improvement in glucose tolerance in an obese rat model.

A new device for intraoperative renal blood flow measurement during open-heart surgery: an experimental study and the clinical pilot study.

Science.gov (United States)

Tirilomis, Theodor; Popov, Aron F; Hanekop, Gunnar G; Braeuer, Anselm; Quintel, Michael; Schoendube, Friedrich A; Friedrich, Martin G

2013-10-01

Renal blood flow (RBF) may vary during cardiopulmonary bypass and low flow may cause insufficient blood supply of the kidney triggering renal failure postoperatively. Still, a valid intraoperative method of continuous RBF measurement is not available. A new catheter combining thermodilution and intravascular Doppler was developed, first calibrated in an in vitro model, and the catheter specific constant was determined. Then, application of the device was evaluated in a pilot study in an adult cardiovascular population. The data of the clinical pilot study revealed high correlation between the flow velocities detected by intravascular Doppler and the RBF measured by thermodilution (Pearson's correlation range: 0.78 to 0.97). In conclusion, the RBF can be measured excellently in real time using the new catheter, even under cardiopulmonary bypass. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

Development of an economical and ecological optimized multi slot fish bypass

International Nuclear Information System (INIS)

Tauber, M.; Mader, H.

2009-01-01

The European Union's Water Framework Directive (WFD), which came into force in 2000, represents a new framework governing water policies. The ecological objectives of the directive are sometimes in conflict with the historical use of waterbodies for hydropower generation. This paper discussed the mitigation of negative economical effects caused by outfitting hydropower plants with fish migration facilities claimed by the WFD. In particular, it reviewed the new modified version of the Vertical Slot Fishpass which reduces water discharge while maintaining or even enhancing the biological migration of aquatic species. Reducing the flow rate in the fish bypass results in more available water for hydropower generation, which is economically advantageous for operators. The available water resource is simply used more efficiently. The bypass was modified by adding additional slot baffles and guide walls in order to induce intended losses at roughness obstacles and to obtain isolated roughness current in the multi slot area. A Froude similarity model was used to obtain the results of the first phase of this project. Different arrangements of the slot baffles and locations were measured. The results of all trials revealed that the newly developed multi slot variants have clear advantages over conventional vertical slot fish passages. Discharge was reduced by up to 34 per cent while still maintaining the same water levels in the pools. As such, the general flow velocities were also reduced by about 10 per cent, thereby achieving the primary objective of the project. 7 refs., 18 figs

Fluid distribution kinetics during cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Mattias Törnudd

2014-08-01

Full Text Available OBJECTIVE: The purpose of this study was to examine the isovolumetric distribution kinetics of crystalloid fluid during cardiopulmonary bypass. METHODS: Ten patients undergoing coronary artery bypass grafting participated in this prospective observational study. The blood hemoglobin and the serum albumin and sodium concentrations were measured repeatedly during the distribution of priming solution (Ringer's acetate 1470 ml and mannitol 15% 200 ml and initial cardioplegia. The rate of crystalloid fluid distribution was calculated based on 3-min Hb changes. The preoperative blood volume was extrapolated from the marked hemodilution occurring during the onset of cardiopulmonary bypass. Clinicaltrials.gov: NCT01115166. RESULTS: The distribution half-time of Ringer's acetate averaged 8 minutes, corresponding to a transcapillary escape rate of 0.38 ml/kg/min. The intravascular albumin mass increased by 5.4% according to mass balance calculations. The preoperative blood volume, as extrapolated from the drop in hemoglobin concentration by 32% (mean at the beginning of cardiopulmonary bypass, was 0.6-1.2 L less than that estimated by anthropometric methods (p<0.02. The mass balance of sodium indicated a translocation from the intracellular to the extracellular fluid space in 8 of the 10 patients, with a median volume of 236 ml. CONCLUSIONS: The distribution half-time of Ringer's solution during isovolumetric cardiopulmonary bypass was 8 minutes, which is the same as for crystalloid fluid infusions in healthy subjects. The intravascular albumin mass increased. Most patients were hypovolemic prior to the start of anesthesia. Intracellular edema did not occur.

A PWR reactor downcomer modification for reduction of ECC bypass flow during LOCA

International Nuclear Information System (INIS)

Popov, N.; Bosevski, T.

1986-01-01

The ECC bypass phenomenon in the PWR reactor down-comer, which delays the reactor vessel refilling, after cold leg large break LOCA accident, has been subject of analysis in this paper. In the paper, a particular construction modification of the reactor down-comer has been suggested by inserting vertical ribs, aimed to intensify the reactor ECC refilling following the LOCA accident, and to advance the thermal-hydraulics safety of post-accidental cooling of the PWR reactors. To verify the effectiveness of the suggested down-comer construction modification, some properly selected results, obtained by corresponding verified mathematical model, have been presented in this paper. (author)

Gastric bypass surgery

Science.gov (United States)

... your body will not get all of the calories from the food you eat. ... to a small hole in your pouch. The food you eat will now travel ... absorb fewer calories. Gastric bypass can be done in two ways. ...

The in situ side-to-side bypass technique: a comprehensive review of the technical characteristics, current anastomosis approaches and surgical experience.

Science.gov (United States)

Wang, Long; Cai, Li; Qian, Hai; Lawton, Michael T; Shi, Xiang'en

2018-05-02

In situ side-to-side (STS) revascularization is an intracranial-intracranial (IC-IC) bypass technique that is increasingly used to treat complex aneurysms and cerebral ischemia. This sophisticated technique involves connecting two proximal parallel vessels to create an artificial conduit for blood flow. This study aims to provide a detailed description of the configuration of the STS bypass technique and extensive information regarding its technical characteristics, current anastomosis approaches and surgical significance. A literature search was performed using the PubMed, Medline, ScienceDirect, Embase, Wiley Online Library, Cambridge Journals, SAGE Journals, Oxford Journals, Research Gate, and Google Scholar databases. The terms "intracranial-intracranial bypass", "in situ bypass", "communicating bypass" and "STS anastomosis" were searched to identify pertinent articles. Articles involving in situ STS anastomosis combined with other bypass methods were excluded. Computer tablet-drawn illustrations of this technique are provided to enhance comprehension. In total, seventy articles that met our search and inclusion criteria were identified. Overall, the radiographical and clinical outcomes of one-hundred and thirty-two (125 aneurysm and 7 cerebral ischemia) patients who underwent in situ STS revascularization were analyzed. IC-IC bypass in the STS fashion can be a safe and effective strategy for the management of complex intracranial aneurysms and cerebral ischemia and is particularly attractive in rescue, anticipated and troubleshooting cases. Despite its extreme rarity, a de novo aneurysm may be observed following STS anastomosis; thus, long-term follow-up is mandatory. Vascular neurosurgeons should consider including this procedure in their treatment armamentarium. Copyright © 2018. Published by Elsevier Inc.

Breast cancer biomarkers predict weight loss after gastric bypass surgery

Directory of Open Access Journals (Sweden)

Sauter Edward R

2012-01-01

Full Text Available Abstract Background Obesity has long been associated with postmenopausal breast cancer risk and more recently with premenopausal breast cancer risk. We previously observed that nipple aspirate fluid (n levels of prostate specific antigen (PSA were associated with obesity. Serum (s levels of adiponectin are lower in women with higher body mass index (BMI and with breast cancer. We conducted a prospective study of obese women who underwent gastric bypass surgery to determine: 1 change in n- and s-adiponectin and nPSA after surgery and 2 if biomarker change is related to change in BMI. Samples (30-s, 28-n and BMI were obtained from women 0, 3, 6 and 12 months after surgery. Findings There was a significant increase after surgery in pre- but not postmenopausal women at all time points in s-adiponectin and at 3 and 6 months in n-adiponectin. Low n-PSA and high s-adiponectin values were highly correlated with decrease in BMI from baseline. Conclusions Adiponectin increases locally in the breast and systemically in premenopausal women after gastric bypass. s-adiponectin in pre- and nPSA in postmenopausal women correlated with greater weight loss. This study provides preliminary evidence for biologic markers to predict weight loss after gastric bypass surgery.

Use of laser-scan technology to analyse topography and flow in a weir pool

Directory of Open Access Journals (Sweden)

P. E. Dresel

2012-08-01

Full Text Available The development of laser-scan techniques provides opportunity for detailed terrain analysis in hydrologic studies. Ground based scans were used to model the ground surface elevation in the area of a stream gauge weir over an area of 240 m² at a resolution of 0.05 m. The terrain model was used to assess the possibility of flow bypassing the weir and to calculate stream flow during filling of the weir pool, prior to flow through the weir notch. The mapped surface shows a subtle low-lying area at the south end of the structure where flow could bypass the weir. The flow calculations quantify low-flows that do not reach the weir notch during small rain events and flow at the beginning of larger events in the ephemeral stream.

Prediction of the external work of the native heart from the dynamic H-Q curves of the rotary blood pumps during left heart bypass.

Science.gov (United States)

Yokoyama, Yoshimasa; Kawaguchi, Osamu; Kitao, Takashi; Kimura, Taro; Steinseifer, Ulrich; Takatani, Setsuo

2010-09-01

The ventricular performance is dependent on the drainage effect of rotary blood pumps (RBPs) and the performance of RBPs is affected by the ventricular pulsation. In this study, the interaction between the ventricle and RBPs was examined using the pressure-volume (P-V) diagram of the ventricle and dynamic head pressure-bypass flow (H-Q) curves (H, head pressure: arterial pressure minus ventricular pressure vs. Q, bypass flow) of the RBPs. We first investigated the relationships in a mock loop with a passive fill ventricle, followed by validation in ex vivo animal experiments. An apical drainage cannula with a micro-pressure sensor was especially fabricated to obtain ventricular pressure, while three pairs of ultrasonic crystals placed on the heart wall were used to derive ventricular volume. The mock loop-configured ventricular apical-descending aorta bypass revealed that the external work of the ventricle expressed by the area inside the P-V diagrams (EW(Heart) ) correlated strongly with the area inside dynamic H-Q curves (EW(VAD)), with the coefficients of correlation being R² = 0.869 ∼ 0.961. The results in the mock loop were verified in the ex vivo studies using three Shiba goats (10-25 kg in body weight), showing the correlation coefficients of R² = 0.802 ∼ 0.817. The linear regression analysis indicated that the increase in the bypass flow reduced pulsatility in the ventricle expressed in EW(Heart) as well as in EW(VAD) . Experimental results, both mock loop and animal studies, showed that the interaction between cardiac external work and H-Q performance of RBPs can be expressed by the relationships "EW(Heart) versus EW(VAD) ." The pulsatile nature of the native heart can be expressed in the area underneath the H-Q curves of RBPs EW(VAD) during left heart bypass indicating the status of the level of assistance by RBPs and the native heart function. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and

Modelling of the effect of the foregoing wake on the bypass transition on the airfoil

Directory of Open Access Journals (Sweden)

Šimurda David

2012-04-01

Full Text Available A modified algebraic model of the bypass transition was used for the simulation of the flow around the symmetrical airfoil NACA 0012 in the tandem configuration. The transition model is based on local variables only to enable its application for complex flow geometry using unstructured computational grids. The attention was especially focused on the flow near the leading edge where the boundary layer is not yet fully developed while used empirical correlations were established for the boundary-layer flow. The numerical simulation was compared with experiments of Lee and Kang [1] carried out for the Reynolds number Rec = (2÷6×105, the zero angle of attack and various distance between both airfoils. The agreement of numerical simulation with experimental data is quite satisfactory.

Modelling of high-enthalpy, high-Mach number flows

International Nuclear Information System (INIS)

Degrez, G; Lani, A; Panesi, M; Chazot, O; Deconinck, H

2009-01-01

A review is made of the computational models of high-enthalpy flows developed over the past few years at the von Karman Institute and Universite Libre de Bruxelles, for the modelling of high-enthalpy hypersonic (re-)entry flows. Both flows in local thermo-chemical equilibrium (LTE) and flows in thermo-chemical non-equilibrium (TCNEQ) are considered. First, the physico-chemical models are described, i.e. the set of conservation laws, the thermodynamics, transport phenomena and chemical kinetics models. Particular attention is given to the correct modelling of elemental (LTE flows) and species (chemical non-equilibrium-CNEQ-flows) transport. The numerical algorithm, based on a state-of-the-art finite volume discretization, is then briefly described. Finally, selected examples are included to illustrate the capabilities of the developed solver. (review article)

Aortic valve bypass

DEFF Research Database (Denmark)

Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

2013-01-01

In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). ...

A new veno-venous bypass type for ex-vivo liver resection in dogs.

Science.gov (United States)

Lei, Peng; Liu, Shi-Qi; Cui, Xiao-Hai; Lv, Yi; Zhao, Ge; Li, Jian-Hui

2013-08-01

Ex-vivo liver resection is a procedure in which the liver is completely removed, perfused and after bench surgery, the liver is autotransplanted to the original site. Ex-vivo liver resection is an important treatment for unresectable liver tumors. This surgical procedure requires long operation time, during which blood flow must be carefully maintained to avoid venous congestion. An effective veno-venous bypass (VVB) may meet this requirement. The present study was to test our new designed VVB device which comprised one heparinized polyvinylchloride tube and three magnetic rings. The efficacy of this device was tested in five dogs. A VVB was established in 6-10 minutes. There was no leakage during the procedure. Hemodynamics was stable at anhepatic phase, which indicated that the bypass was successful. This newly-developed VVB device maintained circulation stability during ex-vivo liver resection in our dog model and thus, this VVB device significantly shortened the operation time.

A high performance magnetorheological valve with a meandering flow path

International Nuclear Information System (INIS)

Imaduddin, Fitrian; Amri Mazlan, Saiful; Azizi Abdul Rahman, Mohd; Zamzuri, Hairi; Ubaidillah; Ichwan, Burhanuddin

2014-01-01

The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide. Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved. One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance. This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve. The meandering flow path is formed by combining multiple annular, radial and orifice flow channels. In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve. The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder. The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment

Preferential flow in water-repellent sandy soils : model development and lysimeter experiments

NARCIS (Netherlands)

Rooij, de G.H.

1996-01-01

When water enters a water-repellent topsoil, preferential flow paths develop and the flow bypasses a large part of the unsaturated zone. Therefore, preferential flow caused by water- repellency is expected to accelerate solute leaching to the groundwater. In soils with water-repellent

21 CFR 870.4260 - Cardiopulmonary bypass arterial line blood filter.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass arterial line blood filter... Cardiopulmonary bypass arterial line blood filter. (a) Identification. A cardiopulmonary bypass arterial line blood filter is a device used as part of a gas exchange (oxygenator) system to filter nonbiologic...

21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood through...

21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through the...

Cardiopulmonary bypass: development of John Gibbon's heart-lung machine

Directory of Open Access Journals (Sweden)

Andréia Cristina Passaroni

2015-04-01

Full Text Available AbstractObjective:To provide a brief review of the development of cardiopulmonary bypass.Methods:A review of the literature on the development of extracorporeal circulation techniques, their essential role in cardiovascular surgery, and the complications associated with their use, including hemolysis and inflammation.Results:The advancement of extracorporeal circulation techniques has played an essential role in minimizing the complications of cardiopulmonary bypass, which can range from various degrees of tissue injury to multiple organ dysfunction syndrome. Investigators have long researched the ways in which cardiopulmonary bypass may insult the human body. Potential solutions arose and laid the groundwork for development of safer postoperative care strategies.Conclusion:Steady progress has been made in cardiopulmonary bypass in the decades since it was first conceived of by Gibbon. Despite the constant evolution of cardiopulmonary bypass techniques and attempts to minimize their complications, it is still essential that clinicians respect the particularities of each patient's physiological function.

Steady flow in voids and closed cracks in permeable media

International Nuclear Information System (INIS)

Rae, J.

1985-03-01

This paper considers what happens when a steady flow in a permeable medium meets two concentric spheres which have different permeabilities. This can form a first stage model for water flow near an engineered cavity in rock or a concreted waste package placed in filler material as in a nuclear waste repository. Results are obtained in terms of the simplest spherical harmonics, which lets them be used easily. Included are the well-known result that a highly permeable sphere will see only a few times the flux which would occur if it had the permeability of its surroundings, and the less well-known result, though unsurprising, that a spherical region surrounded by a highly permeable shell will see almost no flow, as it will almost all by-pass. A companion paper will include more geometrical effects by replacing the spheres by ellipsoids. (author)

Perforated marginal ulcers after laparoscopic gastric bypass.

Science.gov (United States)

Felix, Edward L; Kettelle, John; Mobley, Elijah; Swartz, Daniel

2008-10-01

Perforated marginal ulcer (PMU) after laparoscopic Roux-en-Y gastric bypass (LRYGB) is a serious complication, but its incidence and etiology have rarely been investigated. Therefore, a retrospective review of all patients undergoing LRYGB at the authors' center was conducted to determine the incidence of PMU and whether any causative factors were present. A prospectively kept database of all patients at the authors' bariatric center was retrospectively reviewed. The complete records of patients with a PMU were examined individually for accuracy and analyzed for treatment, outcome, and possible underlying causes of the marginal perforation. Between April 1999 and August 2007, 1% of the patients (35/3,430) undergoing laparoscopic gastric bypass experienced one or more perforated marginal ulcers 3 to 70 months (median, 18 months) after LRYGB. The patients with and without perforation were not significantly different in terms of mean age (37 vs 41 years), weight (286 vs 287 lb), body mass index (BMI) (46 vs 47), or female gender (89% vs 83%). Of the patients with perforations, 2 (6%) were taking steroids, 10 (29%) were receiving nonsteroidal antiinflammatory drugs (NSAIDs) at the time of the perforation, 18 (51%) were actively smoking, and 6 of the smokers also were taking NSAIDs. Eleven of the patients (31%) who perforated did not have at least one of these possible risk factors, but 4 (36%) of the 11 patients in this group had been treated after bypass for a marginal ulcer. Only 7 (20%) of the 35 patients who had laparoscopic bypass, or 7 (0.2%) in the entire group of 3,430 patients, perforated without any warning. There were no deaths, but three patients reperforated. The incidence of a marginal ulcer perforating after LRYGB was significant (>1%) and appeared to be related to smoking or the use of NSAIDs or steroids. Because only 0.2% of all patients acutely perforated without some risk factor or warning, long-term ulcer prophylaxis or treatment may be necessary

Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review.

Science.gov (United States)

Ghista, Dhanjoo N; Kabinejadian, Foad

2013-12-13

In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs.

Association between serum lactate and postoperative outcomes following coronary artery bypass graft surgery

Directory of Open Access Journals (Sweden)

Fatemeh Hasanshiri

2017-02-01

Full Text Available Background: Increased serum lactate during cardio-pulmonary bypass is associated with high mortality and cardiac complications up to 10-20 percent. The aim of this study was to evaluate the effect of serum lactate increase on postoperative outcomes after coronary artery bypass graft (CABG Surgery. Materials and Methods: This descriptive-analytical study was performed on cases (no=116 undergoing CABG at Beheshti hospital in Kashan between 2013-2014. Demographic data, variables related to surgery, serum lactate level and the time of tracheal extubation, length of stay in intensive care unit (ICU and hospital post-surgery left ventricular ejection fraction were collected. These data was compared in two groups: Normal serum lactate ( 2 m mol\\liter group. Results: The postoperative hyperlactatemia was observed in 62.1 % of patients. There were no significant differences between two groups in time of tracheal extubation, length of stay in ICU and hospital. There was a relationship between the mean postoperative serum lactate and blood sugar, bicarbonate, pH, length of cardiopulmonary bypass and the aortic cross clamping time. There was a significant relationship between the serum lactate increment and the left ventricular ejection fraction decrement. Conclusion: Hyperlactatemia is probably associated with such important factors as high blood sugar, longer duration of aortic cross clamp and cardio-pulmonary bypass time. So controlling such factors can reduce the rate of hyperlactatemia and help postoperative recovery.

Presentation of a quality management program in off-pump coronary bypass surgery.

Science.gov (United States)

Bougioukakis, Petros; Kluegl, Stefan J; Babin-Ebell, Joerg; Tagarakis, Giorgios I; Mandewirth, Martin; Zacher, Michael; Diegeler, Anno

2014-01-01

To increase the number of off-pump coronary procedures at our institution, a new surgical team was formed. The first 3 years of "learning period" were accompanied by a quality management program aimed to control and adjust the surgical process and to ensure the safety and quality of the procedure. All patients were operated on by the same surgeon between January 2004 and December 2006; all procedures were performed under the following quality management protocol. First, a flow chart regulated surgical and anesthetic details. Second, an online file, named "disturbance file," was used to report work flow interruption, disturbance, and intraoperative events, that is, myocardial ischemia, hypotension, conversion to cardiopulmonary bypass, and any violation of the protocol. Each event was coded with 1 point and added to a score (the higher the score is, the greater the disturbance). Outcome parameters known as major events-major cardiac and cerebral events: mortality within 30 days/myocardial infarction confirmed by electrocardiogram or significantly high levels of total creatine kinase-myocardial muscle creatine kinase/reintervention within 30 days/stroke--and new-onset dialysis were also measured. Success was defined as freedom from any of those events and depicted in a cumulative sum control (CUSUM) chart. Outcome data and CUSUM were correlated with the intraoperative Disturbance Index. In total, 490 off-pump coronary bypass operations were performed by the named surgeon during the study period. The 30-day mortality was reduced from 4.0% to 1.9%. Disturbance Index score of greater than 1 declined from 41.6% to 23.3%. All major cardiac and cerebral events declined. The CUSUM chart showed two critical periods during the learning period, which made an adjustment of the protocol necessary. Quality management control is efficient in improving the postoperative results of a surgical procedure. A learning period is of cardinal importance for any new team wishing to engage

CBF before and after extracranial-intracranial bypass surgery in patients with ischemic cerebrovascular disease studied with 133Xe-inhalation tomography

DEFF Research Database (Denmark)

Vorstrup, S; Lassen, N A; Henriksen, L

1985-01-01

Cerebral blood flow (CBF) was studied by 133Xenon inhalation tomography in 22 patients with symptoms of ischemic cerebrovascular disease before and after establishment of an extracranial-intracranial bypass shunt. Selection of patients for shunting was based on angiographically demonstrated...... arterial occlusions and on the finding of focal low flow areas corresponding to the clinical symptoms, that consisted mainly of minor stroke with good remission and with or without subsequent TIAs. It was required that the area of low flow should clearly exceed the CT lesion present in practically all...

Numerical investigation of a looped-tube travelling-wave thermoacoustic engine with a bypass pipe

International Nuclear Information System (INIS)

Al-Kayiem, Ali; Yu, Zhibin

2016-01-01

A new configuration (“a looped-tube with a bypass pipe”) was recently proposed for low temperature travelling wave thermoacoustic engines and a prototype using atmospheric air as the working gas achieved an onset temperature difference as low as 65 °C. However, no further research has been reported about this new configuration to reveal its advantages and disadvantages. This paper aims to analyse this type of engine through a comprehensive numerical research. An engine of this type having dimensions similar to the reported prototype was firstly modelled. The calculated results were then qualitatively compared with the reported experimental data, showing a good agreement. The working principle of the engine was demonstrated and analysed. The research results show that an engine with such a bypass configuration essentially operates on the same thermodynamic principle as other travelling wave thermoacoustic engines, differing only in the design of the acoustic resonator. Both extremely short regenerators and a near-travelling wave resonator minimise the engine's acoustic losses, and thus significantly reduce its onset temperature difference. However, such short regenerators likely cause severe heat conduction losses, especially if the engine is applied to heat sources with higher temperatures. Furthermore, the acoustic power flowing back to the engine core is relatively low, while a large stream of acoustic power has to propagate within its resonator to maintain an acoustic resonance, potentially leading to low power density. The model was then applied to design an engine with a much longer regenerator and higher mean pressure to increase its power density. A thermoacoustic cooler was also added to the engine to utilise its acoustic power, allowing the evaluation of thermal efficiency. The pros and cons of the engine configuration are then discussed. - Highlights: • Analysed the working principle of a bypass type thermoacoustic engine. • Analysed the pros and

Distinctive striatal dopamine signaling after dieting and gastric bypass.

Science.gov (United States)

Hankir, Mohammed K; Ashrafian, Hutan; Hesse, Swen; Horstmann, Annette; Fenske, Wiebke K

2015-05-01

Highly palatable and/or calorically dense foods, such as those rich in fat, engage the striatum to govern and set complex behaviors. Striatal dopamine signaling has been implicated in hedonic feeding and the development of obesity. Dieting and bariatric surgery have markedly different outcomes on weight loss, yet how these interventions affect central homeostatic and food reward processing remains poorly understood. Here, we propose that dieting and gastric bypass produce distinct changes in peripheral factors with known roles in regulating energy homeostasis, resulting in differential modulation of nigrostriatal and mesolimbic dopaminergic reward circuits. Enhancement of intestinal fat metabolism after gastric bypass may also modify striatal dopamine signaling contributing to its unique long-term effects on feeding behavior and body weight in obese individuals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quality of intraoperative autologous blood withdrawal used for retransfusion after cardiopulmonary bypass.

Science.gov (United States)

Flom-Halvorsen, Hanne I; Øvrum, Eivind; Øystese, Rolf; Brosstad, Frank

2003-09-01

Intraoperative autologous blood withdrawal protects the pooled blood from the deleterious effects of cardiopulmonary bypass. Following reinfusion after cardiopulmonary bypass, the fresh autologous blood contributes to less coagulation abnormalities and reduces postoperative bleeding and the need for allogeneic blood products. However, few data have been available concerning the quality and potential activation of fresh blood stored at room temperature in the operating room. Forty coronary artery bypass grafting patients undergoing a consistent intraoperative and postoperative autotransfusion protocol had a median of 1,000 mL of autologous blood withdrawn before cardiopulmonary bypass. After heparinization the blood was drained from the venous catheter via venous cannula into standard blood bags and stored in the operating room until termination of cardiopulmonary bypass. Samples for hemostatic and inflammatory markers were taken from the pooled blood immediately before it was returned to the patient. There was some activation of platelets in the stored autologous blood, as measured by an increase of beta-thromboglobulin. Indications of thrombin formation, as assessed by plasma levels of thrombin-antithrombin complex and prothrombin fragment 1.2 were not seen, and there was no fibrinolytic activity. The red blood cells remained intact, indicated by the absence of plasma free hemoglobin. As for the inflammatory response, the levels of the terminal complement complex remained stable, and the cytokines tumor necrosis factor-alpha and interleukin 6 levels were not increased during storage. The complement activation products increased minimally, but remained within normal ranges. Except for slight activation of platelets, there was no indication of coagulation, hemolysis, fibrinolysis, or immunologic activity in the autologous blood after approximately 1 hour of operating room storage. The autologous blood was preserved in a condition of high quality, and retransfusion

Digital subtraction angiography (DSA) of aortocoronary bypass grafts in the early postoperative phase with peripheral-venous contrast medium injection

International Nuclear Information System (INIS)

Tuengerthal, S.; Lang, J.; Donhoeffner, A.

1985-01-01

Using a fully digitalised subtraction unit, aortocoronary bypass grafts can be visualised in the early postoperative phase by means of peripheral venous contrast medium injection (57 out of a total of 60 cases). In more than one-half of the cases (31 out of a total of 60), it is possible to outline sharply the bypass grafts from the beginning to their entry into the bridged-over coronary artery, in such a manner that any loops, kinks, stenoses or reduced flow rates can be recognised. This examination is not considered to be an invasive one by the patient, and the cardiosurgeon can welcome it as a valuable additional means of controlling and assessing the results of surgery. (orig.) [de

Coronary Artery Bypass Grafting

Science.gov (United States)

... lung bypass machine is used during this procedure. Robot-assisted technique. This type of procedure allows for ... driving after 3 to 8 weeks. Returning to work after 6 weeks is common unless your job ...

21 CFR 870.4200 - Cardiopulmonary bypass accessory equipment.

Science.gov (United States)

2010-04-01

... Cardiopulmonary bypass accessory equipment. (a) Identification. Cardiopulmonary bypass accessory equipment is a... mounting bracket or system-priming equipment. (b) Classification. (1) Class I. The device is classified as class I if it does not involve an electrical connection to the patient. The device is exempt from the...

Anesthesia for off-pump coronary artery bypass surgery

Directory of Open Access Journals (Sweden)

Thomas M Hemmerling

2013-01-01

Full Text Available The evolution of techniques and knowledge of beating heart surgery has led anesthesia toward the development of new procedures and innovations to promote patient safety and ensure high standards of care. Off-pump coronary artery bypass (OPCAB surgery has shown to have some advantages compared to on-pump cardiac surgery, particularly the reduction of postoperative complications including systemic inflammation, myocardial injury, and cerebral injury. Minimally invasive surgery for single vessel OPCAB through a limited thoracotomy incision can offer the advantage of further reduction of complications. The anesthesiologist has to deal with different issues, including hemodynamic instability and myocardial ischemia during aorto-coronary bypass grafting. The anesthesiologist and surgeon should collaborate and plan the best perioperative strategy to provide optimal care and ensure a rapid and complete recovery. The use of high thoracic epidural analgesia and fast-track anesthesia offers particular benefits in beating heart surgery. The excellent analgesia, the ability to reduce myocardial oxygen consumption, and the good hemodynamic stability make high thoracic epidural analgesia an interesting technique. New scenarios are entering in cardiac anesthesia: ultra-fast-track anesthesia with extubation in the operating room and awake surgery tend to be less invasive, but can only be performed on selected patients.

Evaluation of waste temperatures in AWF tanks for bypass mode operation of the 702-AZ ventilation system (Project W-030)

International Nuclear Information System (INIS)

Sathyanarayana, K.

1997-01-01

This report describes the results of thermal hydraulic analysis performed to provide data in support of Project W-030 to startup new 702-AZ Primary Ventilation System. During the startup of W-030 system, the ventilation system will be operating in bypass mode. In bypass made of operation, the system is capable of supplying 1000 cfm total flow for all four AWF doubleshell tanks. The design of the W-030 system is based on the assumption that both the recirculation loop of the primary ventilation system and the secondary ventilation which provides cooling would be operating. However, during the startup neither the recirculation system nor the secondary ventilation system will be operating. A minimum flow of 100 cfm is required to prevent any flammable gas associated risk. The remaining 600 cfm flow can be divided among the four tanks as necessary to keep the peak sludge temperatures below the operating temperature limit. For the purpose of determining the minimum flow required for cooling each tank, the thermal hydraulic analysis is performed to predict the peak sludge temperatures in AY/AZ tanks under different ventilation flows. The heat load for AZ farm tanks is taken from characterization reports and for the AY farm tanks, the heat load was estimated by thermal analysis using the measured waste temperatures and the waste liquid evaporation rates. The tank 241-AZ-101 and the tank 241-AZ-102 have heat loads of 241,600 and 199,500 Btu/hr respectively. The tank 241-AY-101 and tank 241-AY-102 have heat loads of 41,000 and 33,000 Btu/hr respectively. Using the ambient meteorological conditions of temperature and relative humidity for the air and tank, some soil surface and the sludge levels reported in recent documents, the peak sludge and supernatant temperatures were predicted for various primary ventilation flows ranging from 100 to 400 cfm for AZ tanks and 100 and 150 cfm for AY tanks. The results of these thermal hydraulic analyses are presented. Based on the

The Serial Change of Cerebral Hemodynamics by Vascular Territory after Extracranial-Intracranial Bypass Surgery in Patients with Atherosclerosis of Cerebral Arteries

International Nuclear Information System (INIS)

Hong, Il Ki; Kim, Jae Seung; Ahn, Jae Sung; Kwon, Sun Uck; Im, Ki Chun; Lee, Jai Hyuen; Moon, Dae Hyuk

2008-01-01

To assess the effect of extracranial-intracranial (EC-IC) bypass surgery on hemodynamic improvement, we evaluated serial regional cerebral hemodynamic change of the middle cerebral artery (MCA) in symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or MCA using 99m Tc-ECD acetazolamide stress brain perfusion SPECT (Acetazolamide SPECT). The patients who had suffered a recent stroke with atherosclerotic ICA or MCA occlusion underwent EC-IC bypass surgery and Acetazolamide SPECT at 1 week before and three to six months after surgery. For image analysis, attenuation corrected images were spatially normalized to SPECT templates with SPM2. Anatomical automated labeling was applied to calculate mean counts of each Volume-Of-Interest (VOI). Seven VOIs of bilateral frontal, parietal, temporal regions of the MCA territory and the ipsilateral cerebellum were defined. Using mean counts of 7 VOIs, cerebral perfusion index and perfusion reserve index were calculated. Seventeen patients (M:F=12:5, mean age: 53±2yr) were finally included in the analysis. The cerebral blood flow of the parietal region increased at 1 week (p=0.003) and decreased to the preoperative level at 3-6 months (p=0.003). The cerebrovascular reserve of the frontal and parietal regions increased significantly at 1 week after surgery (p<0.01) and improved further at 3-6 months. Cerebrovascular reserve of the MCA territory was significantly improved at early postoperative period after EC-IC bypass and kept improved state during long-term follow-up, although cerebral blood flow did not significantly improved. Therefore, cerebrovascular reserve may be a good indicator of postoperative hemodynamic improvement resulted from bypass effect

The Serial Change of Cerebral Hemodynamics by Vascular Territory after Extracranial-Intracranial Bypass Surgery in Patients with Atherosclerosis of Cerebral Arteries

Energy Technology Data Exchange (ETDEWEB)

Hong, Il Ki; Kim, Jae Seung; Ahn, Jae Sung; Kwon, Sun Uck; Im, Ki Chun; Lee, Jai Hyuen; Moon, Dae Hyuk [Asan Medial Center, Ulsan University School of Medicine, Seoul (Korea, Republic of)

2008-02-15

To assess the effect of extracranial-intracranial (EC-IC) bypass surgery on hemodynamic improvement, we evaluated serial regional cerebral hemodynamic change of the middle cerebral artery (MCA) in symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or MCA using {sup 99m}Tc-ECD acetazolamide stress brain perfusion SPECT (Acetazolamide SPECT). The patients who had suffered a recent stroke with atherosclerotic ICA or MCA occlusion underwent EC-IC bypass surgery and Acetazolamide SPECT at 1 week before and three to six months after surgery. For image analysis, attenuation corrected images were spatially normalized to SPECT templates with SPM2. Anatomical automated labeling was applied to calculate mean counts of each Volume-Of-Interest (VOI). Seven VOIs of bilateral frontal, parietal, temporal regions of the MCA territory and the ipsilateral cerebellum were defined. Using mean counts of 7 VOIs, cerebral perfusion index and perfusion reserve index were calculated. Seventeen patients (M:F=12:5, mean age: 53{+-}2yr) were finally included in the analysis. The cerebral blood flow of the parietal region increased at 1 week (p=0.003) and decreased to the preoperative level at 3-6 months (p=0.003). The cerebrovascular reserve of the frontal and parietal regions increased significantly at 1 week after surgery (p<0.01) and improved further at 3-6 months. Cerebrovascular reserve of the MCA territory was significantly improved at early postoperative period after EC-IC bypass and kept improved state during long-term follow-up, although cerebral blood flow did not significantly improved. Therefore, cerebrovascular reserve may be a good indicator of postoperative hemodynamic improvement resulted from bypass effect.

Changes in adhesion molecule expression and oxidative burst activity of granulocytes and monocytes during open-heart surgery with cardiopulmonary bypass compared with abdominal surgery

DEFF Research Database (Denmark)

Toft, P; Nielsen, C H; Tønnesen, E

1998-01-01

surgery. The ability to respond with an oxidative burst was measured by means of flow cytometry using 123-dihydrorhodamine. The adhesion molecules CD11a/CD18, CD11c/CD18, CD44 were measured using monoclonal antibodies. Blood samples from eight patients undergoing open-heart surgery were taken before...... to an increased per-operative oxidative burst activity, and the induction of adhesion molecules on granulocytes associated with the cardiopulmonary bypass and surgery. In conclusion, open-heart surgery with cardiopulmonary bypass was associated with a rapid and pronounced activation of leukocytes which may play...

Changes in the vessels following aorto-coronary bypass operation

International Nuclear Information System (INIS)

Goebel, N.; Pfluger, N.; Speiser, K.; Turina, M.; Rothlin, M.; Zurich Univ.; Zurich Univ.

1983-01-01

In a prospective study (238 men, mean age 53 years) the changes of the native vessels were studied 3 months after a-c-bypass operation and 5 months after preop. angiography. Progression was defined as increase of stenoses of at least 20% or new total occlusion. Progression was significantly more frequent in vessels with than without bypass and was located proximally to the anastomoses in most cases, less frequently at the anastomoses and very rarely distally to the anastomoses. Proximal progression was significantly more frequent with patent than with occluded bypasses. Stenoses at the anastomoses were significantly more frequent with occluded than with patent bypasses. Stenoses of higher degrees hat a stonger tendency for progression than slighter stenoses. Regression was rare and nearly always caused by surgery. (orig.) [de

Off-Pump Versus On-Pump Coronary Artery Bypass Grafting

DEFF Research Database (Denmark)

Møller, Christian H; Steinbrüchel, Daniel A

2014-01-01

Coronary artery bypass grafting (CABG) remains the preferred treatment in patients with complex coronary artery disease. However, whether the procedure should be performed with or without the use of cardiopulmonary bypass, referred to as off-pump and on-pump CABG, is still up for debate....... Intuitively, avoidance of cardiopulmonary bypass seems beneficial as the systemic inflammatory response from extracorporeal circulation is omitted, but no single randomized trial has been able to prove off-pump CABG superior to on-pump CABG as regards the hard outcomes death, stroke or myocardial infarction....... In contrast, off-pump CABG is technically more challenging and may be associated with increased risk of incomplete revascularization. The purpose of the review is to summarize the current literature comparing outcomes of off-pump versus on-pump coronary artery bypass surgery....

High flow ceramic pot filters

OpenAIRE

van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

2017-01-01

Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6–19 L h−1), but initial LRVs for E. coli o...

Comparison of influence of high thoracic epidural anesthesia and central analgesia on hemodynamic during on-bypass coronary artery bypass grafting

Directory of Open Access Journals (Sweden)

V. A. Sobokar

2015-06-01

Full Text Available Objective. Despite some advantages, the use of high thoracic epidural anesthesia (HTEA during cardiac operations may be discouraged by fear of adverse hemodynamic effects. Aim. To compare the hemodynamic effects of HTEA and central analgesia (CA during on-bypass CABG. Methods. 132 patients were assigned into two groups – study group (n = 85, where the surgery was carried out under HTEA and control group (n = 47 - where the surgery was carried out under CA. Data of the intraoperative monitoring and trans-oesophageal cardiac ultrasound - cardiac index (CI, stroke index (SI, ejection fraction (EF and index of systemic vascular resistance (ISVR were obtained. Results. After induction and sternotomy patients in the study group had higher EF - 57(53, 65% vs 54 ± 7% (p = 0,013 and 55 ± 8 vs 52 ± 9%, (p = 0,031. After sternotomy CI and SI in the study group were also higher, respectively 2,42 (2,0;3,1 vs 2,23±0,63 l · min-1 · m-2, (p = 0,041 and 43 (34;46 vs 37±10 ml · m-2 (p = 0.014. Conclusion. We concluded that HTEA has advantages over CA by its influence on hemodynamics.

Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors

Science.gov (United States)

Tun, Min Thaw; Sakaguchi, Daisaku

2016-06-01

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. It is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

Successful flow reduction surgery for a ruptured true posterior communicating artery aneurysm caused by the common carotid artery ligation for epistaxis.

Science.gov (United States)

Yamao, Yukihiro; Takahashi, Jun C; Satow, Tetsu; Iihara, Koji; Miyamoto, Susumu

2014-01-01

Carotid artery occlusion can lead to the development of rare true posterior communicating artery (PCoA) aneurysms because of hemodynamic stress on the PCoA. Surgical treatment of these lesions is challenging. The authors report a case of a true PCoA aneurysm that developed and ruptured 37 years after ligation of the ipsilateral common carotid artery for epistaxis. The lesion was successfully treated with clipping of the distal M1 segment of the middle cerebral artery (MCA) after the occipital artery-radial artery free graft-MCA bypass, which led to extreme reduction in collateral flow through the PCoA. A cortical branch, located just proximal to the obliteration site, functioned as a sufficient flow outlet. The aneurysm shrank, and the patient has been doing well without any symptoms for 5 years after surgery. M1 obliteration combined with high-flow extra-intracranial bypass might be a promising option for a true PCoA aneurysm, and therapeutic design that leaves a sufficient flow outlet on the M1 is mandatory to avoid unexpected occlusion of the M1 and its perforators.

Predictors of inotrope use in patients undergoing concomitant coronary artery bypass graft (CABG and aortic valve replacement (AVR surgeries at separation from cardiopulmonary bypass (CPB

Directory of Open Access Journals (Sweden)

Nelson William B

2009-06-01

Full Text Available Abstract Background Left ventricular dysfunction is common after coronary artery bypass graft and valve replacement surgeries and is often treated with inotropic drugs to maintain adequate hemodynamic status. In this study, we aimed to identify the demographic, clinical, laboratory, echocardiographic and hemodynamic factors that are associated with use of inotropic drugs in patients undergoing concomitant coronary artery bypass graft and aortic valve replacement surgery. Methods The study included 97 patients who had undergone concomitant coronary artery bypass graft and aortic valve replacement at Regions Hospital, University of Minnesota Medical School from January 2006 to December 2008. All data were collected retrospectively after reviewing electronic medical records. Inotropic support was defined as the use of dopamine [greater than or equal to] 5 ug/kg/min; any dose of epinephrine, norepinephrine, dobutamine, and milrinone at the separation from cardiopulmonary bypass. Results Inotropic support was used in a total of 50 patients (52% at the separation from cardiopulmonary bypass. Average age of the patients requiring inotropic support was 72.2 +/- 8.8 years. The study identified four significant, independent predictors of inotrope use: (1 Cardiac index [less than or equal to]2.5 L/min/m2, (2 LVEDP [greater than or equal to] 20 mm Hg, (3 LVEF [less than or equal to]40%, and (4 CKD stage 3 to 5. Conclusion We identified four independent risk factors for postoperative use of inotropic support in patients undergoing concomitant coronary artery bypass graft and arotic valve replacement surgery at the separation from cardiopulmonary bypass. The study results will be helpful to prospectively identify patients who will likely to require inotropic support at the separation from cardiopulmonary bypass.

Methylene Blue for Vasoplegia When on Cardiopulmonary Bypass During Double-Lung Transplantation.

Science.gov (United States)

Carley, Michelle; Schaff, Jacob; Lai, Terrance; Poppers, Jeremy

2015-10-15

Vasoplegia syndrome, characterized by hypotension refractory to fluid resuscitation or high-dose vasopressors, low systemic vascular resistance, and normal-to-increased cardiac index, is associated with increased morbidity and mortality after cardiothoracic surgery. Methylene blue inhibits inducible nitric oxide synthase and guanylyl cyclase, and has been used to treat vasoplegia during cardiopulmonary bypass. However, because methylene blue is associated with increased pulmonary vascular resistance, its use in patients undergoing lung transplantion has been limited. Herein, we report the use of methylene blue to treat refractory vasoplegia during cardiopulmonary bypass in a patient undergoing double-lung transplantation.

Monsanto may bypass NIH in microbe test.

Science.gov (United States)

Sun, Marjorie

1985-01-11

The Monsanto Company is planning to ask the Environmental Protection Agency for clearance to field test a genetically engineered microbial pesticide, bypassing the traditional approval process of the National Institutes of Health. Although only federally funded institutions are required to obtain NIH approval for genetic engineering tests, Monsanto is the first company to bypass the NIH regulatory process, which has become mired in a lawsuit brought by Jeremy Rifkin.

Experimental study of the core grid by-pass orifices inlet pressure drop of the new core of the R A 6 reactor

International Nuclear Information System (INIS)

Masson, V. P; Garcia, J. C; Delmastro, D. F

2006-01-01

In this work the core grid by-pass orifices inlet pressure drop of the new core of the R A6 reactor are experimentally studied.The experiments are performed using a 1:1 scale mock-up of an external fuel element cell.Different gaps between fuel elements are considered in order to take into account the design allowances. Different flows are considered to take into account the normal operation flow range.Measurement uncertainties are included.The results will be used to calculate the core flow distribution [es

21 CFR 870.4410 - Cardiopulmonary bypass in-line blood gas sensor.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass in-line blood gas sensor... Cardiopulmonary bypass in-line blood gas sensor. (a) Identification. A cardiopulmonary bypass in-line blood gas sensor is a transducer that measures the level of gases in the blood. (b) Classification. Class II...

Cardiopulmonary bypass and hemostasis

NARCIS (Netherlands)

Eijsman, Leon

1992-01-01

In chapter 1, we recalled that intracardiac defects can only be corrected when cardiopulmonary circulation is maintained by extracorporeal criculation and ventilation. To prevent clot formation in this artificial circuit, the socalled cardiopulmonary bypass (CPB), we completely depend on the

Outcome after VAC® therapy for infected bypass grafts in the lower limb.

Science.gov (United States)

Acosta, S; Monsen, C

2012-09-01

To assess the outcome of vacuum-assisted wound closure (VAC(®)) therapy for infected bypass grafts. A retrospective 7-year review of patient records from 2004 to 2011 of all patients receiving VAC(®) therapy for infected bypass grafts. Thirty-seven patients with 42 wounds and 45 infected bypass (28 synthetic) grafts received VAC(®) treatment. Two serious bleeding episodes from the suture lines occurred. The median VAC(®) therapy time was 20 days. The proportion of patent bypass grafts was 91% (41/45) at a median time of 3.5 months from the start of VAC(®) therapy. Five patients with seven bypasses had persistent infection or re-infection, and the total graft preservation rate was 76% (34/45). The median follow-up time was 15 months. The presence of two infected bypass grafts in one groin wound was associated with an increased major amputation rate (hazard ratio (HR) 7.4 [95% confidence interval (CI) 2.0-27.5]), and synthetic graft infection (HR 5.0 [95% CI 1.5-17.4]) and non-healed wound (HR 3.6 [95% CI 1.5-8.7]) were associated with mortality. VAC(®) therapy of infected bypass grafts was able to induce effective wound healing without compromising the early bypass function. Two infected synthetic bypasses in the wound were associated with the highest risk of adverse outcome. Copyright © 2012 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Crohn’s disease after gastric bypass surgery

OpenAIRE

Janczewska, Izabella; Nekzada, Qayium; Kapraali, Marjo

2011-01-01

Bariatric surgery for the treatment of severe obesity has increased dramatically in recent years in the USA and parts of Western Europe. The most commonly used technique is the Roux-en Y gastric bypass (RYGBP). Several nutritional and gastrointestinal complications after bariatric surgery have been described during the last 10 years. The authors present two patients with diarrhoea and malnutrition; one after RYGBP and the other after jejunoileal bypass surgery. These patients were subsequentl...

Bowel habits after gastric bypass versus the duodenal switch operation.

Science.gov (United States)

Wasserberg, Nir; Hamoui, Nahid; Petrone, Patrizio; Crookes, Peter F; Kaufman, Howard S

2008-12-01

One of the perceived disadvantages of the biliopancreatic diversion with duodenal switch operation is diarrhea. The aim of this study was to compare the bowel habits of patients after duodenal switch operation or Roux-en-Y gastric bypass. A prospective comparative case series design was used. Forty-six patients who underwent duodenal switch (n=28) or gastric bypass (n=18) were asked to complete a daily diary for 14 days after losing least 50% of their excess body weight. Data were collected on number of bowel episodes, incontinence, urgency, stool consistency, and awakening from sleep to defecate. Background variables were recorded from the medical files. The duodenal switch group was heavier (body mass index 53.5 vs 47.0 kg/m(2), p=0.03) and older (47.5 vs 41.0 years, p=NS) than the gastric bypass group. Median time to 50% excess body weight loss was 22 months in the duodenal switch group compared to 10.0 months in the gastric bypass group (p=0.001). Patients after duodenal switch surgery reported a median of 23.5 bowel episodes over the 14-day study period compared to 16.5 in the gastric bypass group (p=NS). There was no between-group differences in any of the other bowel parameters studied. Although duodenal switch is associated with more bowel episodes than gastric bypass, the difference is not statistically significant. Bowel habits are similar in patients who achieve 50% estimated body weight loss with duodenal switch surgery or gastric bypass.

Analysis and testing of an inner bypass magnetorheological damper for shock and vibration mitigation

Science.gov (United States)

Bai, Xian-Xu; Hu, Wei; Wereley, Norman M.

2013-04-01

Aiming at fundamentally improving the performance of MR dampers, including maximizing dynamic range (i.e., ratio of field-on to field-off damping force) while simultaneously minimizing field-off damping force, this study presents the principle of an inner bypass magnetorheological damper (IBMRD). The IBMRD is composed of a pair of twin tubes, i.e., the inner tube and outer concentric tube, a movable piston-shaft arrangement, and an annular MR fluid flow gap sandwiched between the concentric tubes. In the IBMRD, the inner tube serves simultaneously as the guide for the movable piston and the bobbin for the electromagnetic coil windings, and five active rings on the inner tube, annular MR fluid flow gap, and outer tube forms five closed magnetic circuits. The annular fluid flow gap is an inner bypass annular valve where the rheology of the MR fluids, and hence the damping force of the MR damper, is controlled. Based on the structural principle of the IBMRD, the IBMRD is configured and its finite element analysis (FEA) is implemented. After theoretically constructing the hydro-mechanical model for the IBMRD, its mathematical model is established using a Bingham-plastic nonlinear fluid model. The characteristics of the IBMRD are theoretically evaluated and compared to those of a conventional piston-bobbin MR damper with an identical active length and cylinder diameter. In order to validate the theoretical results predicted by the mathematical model, the prototype IBMRD is designed, fabricated, and tested. The servo-hydraulic testing machine (type: MTS 810) and rail-guided drop tower are used to provide sinusoidal displacement excitation and shock excitation to the IBMRD, respectively.

Development trend of low bypass ratio turbofan engines. Tei baipasu hi tabo fan engine no kaihatsu doko

Energy Technology Data Exchange (ETDEWEB)

Yashima, S [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

1994-03-10

As a turbojet engine gets a thrust by blowing out the exhaust of a gas generator, for decreasing the fuel consumption ratio is more advantageous when a bypass air quantity is made as much as possible. Therefore in the subsonic speed passenger aircrafts putting an economy in the first place, the high bypass ratio turbofan engines are used. Even in case of the subsonic speed aircrafts, in addition, for the trainer airplanes and fighters, a type to be built in the engines in the fuselages, the low bypass ratio engines with small front areas are used. When a turbofan engine with a low bypass ratio is picked up, therefore recently, it is general that a military engine with a bypass ratio under 1 (about 0.5 is frequent) is pointed, as for a development trend also from a viewpoint of the performance improvement as a military engine, an improvement of the thrust-weight ratio and specific thrust are attached importance to. In this paper, these performance parameters, a trend to make them lighter weight, and the elementary technologies peculiar to a low bypass ratio engine are described, and moreover the study and development state in Europe, America and Japan are put in order. 8 refs., 14 figs., 2 tabs.

A simple method for estimating potential source term bypass fractions from confinement structures

International Nuclear Information System (INIS)

Kalinich, D.A.; Paddleford, D.F.

1997-01-01

Confinement structures house many of the operating processes at the Savannah River Site (SRS). Under normal operating conditions, a confinement structure in conjunction with its associated ventilation systems prevents the release of radiological material to the environment. However, under potential accident conditions, the performance of the ventilation systems and integrity of the structure may be challenged. In order to calculate the radiological consequences associated with a potential accident (e.g. fires, explosion, spills, etc.), it is necessary to determine the fraction of the source term initially generated by the accident that escapes from the confinement structure to the environment. While it would be desirable to estimate the potential bypass fraction using sophisticated control-volume/flow path computer codes (e.g. CONTAIN, MELCOR, etc.) in order to take as much credit as possible for the mitigative effects of the confinement structure, there are many instances where using such codes is not tractable due to limits on the level-of-effort allotted to perform the analysis. Moreover, the current review environment, with its emphasis on deterministic/bounding-versus probabilistic/best-estimate-analysis discourages using analytical techniques that require the consideration of a large number of parameters. Discussed herein is a simplified control-volume/flow path approach for calculating source term bypass fraction that is amenable to solution in a spreadsheet or with a commercial mathematical solver (e.g. MathCad or Mathematica). It considers the effects of wind and fire pressure gradients on the structure, ventilation system operation, and Halon discharges. Simple models are used to characterize the engineered and non-engineered flow paths. By making judicious choices for the limited set of problem parameters, the results from this approach can be defended as bounding and conservative

The impact of avoiding cardiopulmonary by-pass during coronary artery bypass surgery in elderly patients: the Danish On-pump Off-pump Randomisation Study (DOORS)

DEFF Research Database (Denmark)

Houlind, Kim; Kjeldsen, Bo Juul; Madsen, Susanne Nørgaard

2009-01-01

BACKGROUND: Coronary Artery Bypass Graft operation for ischemic heart disease provides improved quality of life and, in some patients, prolonged survival. Concern has, however, been raised about complications that may be related to the use of cardiopulmonary by-pass (CPB) and aortic cross......-clamping. It has been hypothesized that when coronary artery by-pass grafting is performed without the use of CPB, the rate of serious complications is reduced. METHODS/DESIGN: The trial is designed as an open, randomized, controlled, clinical trial with blinded assessment of end-points. Patients at or above 70...... years of age, referred for surgical myocardial revascularisation, are included and randomised to receive coronary artery by-pass grafting either with or without the use of CPB and aortic cross-clamping. Follow-up is performed by clinical, biochemical, electrocardiographic, and angiographic data...

Off-pump versus on-pump coronary artery bypass grafting for ischaemic heart disease

DEFF Research Database (Denmark)

Møller, Christian H; Penninga, Luit; Wetterslev, Jørn

2012-01-01

Coronary artery bypass grafting (CABG) is performed both without and with cardiopulmonary bypass, referred to as off-pump and on-pump CABG respectively. However, the preferable technique is unclear.......Coronary artery bypass grafting (CABG) is performed both without and with cardiopulmonary bypass, referred to as off-pump and on-pump CABG respectively. However, the preferable technique is unclear....

Analysis of pressure drop accidents in high temperature gas-cooled reactors

International Nuclear Information System (INIS)

Kameoka, Toshiyuki

1980-01-01

Research and development are carried out on various problems in order to realize a multi-purpose, high temperature gas-cooled experimental reactor by Japan Atomic Energy Research Institute and others. In the experimental reactor in consideration at present, it is planned to flow helium at 1000 deg C and 40 atm. For the purpose, high temperature heat insulation structures are designed and developed, which insulate heat on the internal surfaces of pressure vessels and pipings. Consideration must be given to these internal heat insulation structures about the various characteristics in the working environmental temperature and pressure conditions, the measures for preventing the by-pass flow due to the formation of gaps and the abnormal leak of heat through the natural convection in the heat insulators and others. In this paper, the experimental results on the rapid pressure reduction characteristics of ceramic fiber heat insulation structures are reported. The ceramic fiber heat insulation structures have the features such as the application to uneven surfaces and penetration parts, the prevention of by-pass flow, and very low permeability. The problem is the restoring force after the high temperature compression. The experiment on rapid pressure reduction due to the accidental release of gas and the results are reported. (Kako, I.)

Thermal activation of dislocations in large scale obstacle bypass

Science.gov (United States)

Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

2017-08-01

Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

MRI: A method to detect minor brain damage following coronary bypass surgery

Energy Technology Data Exchange (ETDEWEB)

Vik, A.; Brubakk, A.O. (Trondheim Univ. (Norway). Dept. of Biomedical Engineering); Rinck, P.A. (Trondheim Univ. (Norway). MR Center); Sande, E.; Levang, O.W. (Trondheim Univ. Hospital (Norway). Dept. of Surgery); Sellevold, O. (Trondheim Univ. Hospital (Norway). Dept. of Anaesthesiology)

1991-10-01

In order to assess the occurrence of minor focal brain lesions after coronary bypass surgery, magnetic resonance imaging (MRI) was used. Nine male patients (age 42-63) with angina pectoris were investigated at 0.5 Tesla. The investigation was performed one to seven weeks prior to the operation and one month after the operation. Before surgery, the images demonstrated more than five high intensity spots in the white matter of the brain in all but two patients. No additional spots were found after operation. This pilot study indicates that it might be difficult to use MRI to detect minor parenchymal lesions after cardiopulmonary bypass surgery. (orig.).

Blood utilization in neonates and infants undergoing cardiac surgery requiring cardiopulmonary bypass.

Science.gov (United States)

Wesley, Mark C; Yuki, Koichi; Daaboul, Dima G; Dinardo, James A

2011-07-01

Neonates and infants undergoing cardiac surgery with cardiopulmonary bypass are exposed to multiple blood products from different donors. The volume of the bypass circuit is often as large as the patient's total blood volume and asanguineous bypass primes are unusual. As a result, blood products are required for the cardiopulmonary bypass prime and are often used to treat the postbypass dilutional coagulopathy. We review clot formation and strength, cardiopulmonary bypass prime considerations, assessment of postbypass coagulopathy, component therapy use, ultrafiltration techniques, and use of antifibrinolytic medications. A combined approach including techniques to minimize the prime volume, utilization of ultrafiltration, administration of antifibrinolytics during surgery, and the proper treatment of the dilutional coagulopathy can limit the transfusion requirements.

Engineered Photorespiratory Bypass Pathways Improve Photosynthetic Efficiency and Growth as Temperature Increases

Science.gov (United States)

Cavanagh, A. P.; South, P. F.; Ort, D. R.; Bernacchi, C.

2017-12-01

In C3 plants grown under ambient [CO2] at 25°C, 23% of the fixed carbon dioxide is lost to photorespiration, the energy expensive metabolic pathway that recycles toxic compounds produced by Rubisco oxygenation reactions. Furthermore, rates of photorespiration increase with rising temperature, as higher temperatures favor increased Rubisco oxygenation. Modelling suggests that the absence of photorespiration could improve gross photosynthesis by 12-55% under projected climate conditions; however, this is difficult to measure empirically, as photorespiration interacts with several metabolic pathways and is an essential process for all C3 plants grown at ambient [O2]. Introduced biochemical bypasses to the native photorespiration pathway hold promise as a strategy to mitigate the impact of temperature on photorespiratory losses. We grew tobacco containing engineered pathways to bypass photorespiration under ambient and elevated temperatures (+5°C) in the field to determine if bypassing photorespiration could mitigate high temperature induced losses in growth and physiology. Our preliminary results show that engineered plants have a higher quantum efficiency under heated conditions than do non-engineered plants, resulting in up to 20% lower yield losses under heated conditions compared to non-engineered plants. These results support the theoretical modelling of temperature impacts on photorespiratory losses, and suggest the bypassing photorespiration could be an important strategy to increase crop yields.

Compressibility, turbulence and high speed flow

CERN Document Server

Gatski, Thomas B

2013-01-01

Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current tre...

Gut hormones and gastric bypass

DEFF Research Database (Denmark)

Holst, Jens J.

2016-01-01

Gut hormone secretion in response to nutrient ingestion appears to depend on membrane proteins expressed by the enteroendocrine cells. These include transporters (glucose and amino acid transporters), and, in this case, hormone secretion depends on metabolic and electrophysiological events elicited...... that determines hormone responses. It follows that operations that change intestinal exposure to and absorption of nutrients, such as gastric bypass operations, also change hormone secretion. This results in exaggerated increases in the secretion of particularly the distal small intestinal hormones, GLP-1, GLP-2......, oxyntomodulin, neurotensin and peptide YY (PYY). However, some proximal hormones also show changes probably reflecting that the distribution of these hormones is not restricted to the bypassed segments of the gut. Thus, cholecystokinin responses are increased, whereas gastric inhibitory polypeptide responses...

Oil Bypass Filter Technology Performance Evaluation - First Quarterly Report

Energy Technology Data Exchange (ETDEWEB)

Zirker, L.R.; Francfort, J.E.

2003-01-31

This report details the initial activities to evaluate the performance of the oil bypass filter technology being tested by the Idaho National Engineering and Environmental Laboratory (INEEL) for the U.S. Department of Energy's FreedomCAR & Vehicle Technologies Program. Eight full-size, four-cycle diesel-engine buses used to transport INEEL employees on various routes have been equipped with oil bypass systems from the puraDYN Corporation. Each bus averages about 60,000 miles a year. The evaluation includes an oil analysis regime to monitor the presence of necessary additives in the oil and to detect undesirable contaminants. Very preliminary economic analysis suggests that the oil bypass system can reduce life-cycle costs. As the evaluation continues and oil avoidance costs are quantified, it is estimated that the bypass system economics may prove increasingly favorable, given the anticipated savings in operational costs and in reduced use of oil and waste oil avoidance.

Percutaneous transhepatic biliary stenting vs. surgical bypass in advanced malignant biliary obstruction: cost- effectiveness analysis.

Science.gov (United States)

Yao, Li Qin; Tang, Cheng Wu; Zheng, Yin Yuan; Feng, Wen Ming; Huang, San Xiong; Bao, Ying

2013-01-01

This study aims to compare the clinical outcomes and costs between percutaneous transhepatic biliary stenting (PTBS) and surgical bypass. We randomly assigned 142 patients with unresectable malignant biliary obstruction between 2005 and 2010 to receive PTBS or surgical bypass as palliative treatment. PTBS was successfully performed in 70 patients who formed the PTBS group (failed in 7 patients). Sixty five patients underwent surgical bypass treatment. Additional gastrojejunostomy was performed in five patients. The effectiveness of biliary drainage, hospital stay, complications, cost, survival time and mortality were compared. Patients in PTBS group had shorter hospital stay and lower initial and overall expense than the surgical group (pPTBS group was significantly lower than surgical group (3/75 vs. 11/65, p=0.0342). Late complication in PTBS group did not differ significantly from surgical group (9/70 vs. 6/65, p=0.6823). The survival curves in the two groups showed no significant difference (p=0.1032). PTBD is a better palliative treatment than surgical bypass for unresectable malignant biliary obstruction for its high effectiveness of biliary drainage and acceptable expense and complication.

p21 is Responsible for Ionizing Radiation-induced Bypass of Mitosis.

Science.gov (United States)

Zhang, Xu Rui; Liu, Yong Ai; Sun, Fang; Li, He; Lei, Su Wen; Wang, Ju Fang

2016-07-01

To explore the role of p21 in ionizing radiation-induced changes in protein levels during the G2/M transition and long-term G2 arrest. Protein expression levels were assessed by western blot in the human uveal melanoma 92-1 cells after treatment with ionizing radiation. Depletion of p21 was carried out by employing the siRNA technique. Cell cycle distribution was determined by flow cytometry combined with histone H3 phosphorylation at Ser28, an M-phase marker. Senescence was assessed by senescence- associated-β-galactosidase (SA-β-gal) staining combined with Ki67 staining, a cell proliferation marker. Accompanying increased p21, the protein levels of G2/M transition genes declined significantly in 92-1 cells irradiated with 5 Gy of X-rays. Furthermore, these irradiated cells were blocked at the G2 phase followed by cellular senescence. Depletion of p21 rescued radiation-induced G2 arrest as demonstrated by the upregulation of G2/M transition kinases, as well as the high expression of histone H3 phosphorylated at Ser28. Knockdown of p21 resulted in entry into mitosis of irradiated 92-1 cells. However, cells with serious DNA damage failed to undergo cytokinesis, leading to the accumulation of multinucleated cells. Our results indicated that p21 was responsible for the downregulation of G2/M transition regulatory proteins and the bypass of mitosis induced by irradiation. Downregulation of p21 by siRNA resulted in G2-arrested cells entering into mitosis with serious DNA damage. This is the first report on elucidating the role of p21 in the bypass of mitosis. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Graft type for femoro-popliteal bypass surgery.

Science.gov (United States)

Ambler, Graeme K; Twine, Christopher P

2018-02-11

Femoro-popliteal bypass is implemented to save limbs that might otherwise require amputation, in patients with ischaemic rest pain or tissue loss; and to improve walking distance in patients with severe life-limiting claudication. Contemporary practice involves grafts using autologous vein, polytetrafluoroethylene (PTFE) or Dacron as a bypass conduit. This is the second update of a Cochrane review first published in 1999 and last updated in 2010. To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro-popliteal arterial segment, for above- and below-knee femoro-popliteal bypass grafts. For this update, the Cochrane Vascular Information Specialist searched the Vascular Specialised Register (13 March 2017) and CENTRAL (2017, Issue 2). Trial registries were also searched. We included randomised trials comparing at least two different types of femoro-popliteal grafts for arterial reconstruction in patients with femoro-popliteal ischaemia. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included. Both review authors (GKA and CPT) independently screened studies, extracted data, assessed trials for risk of bias and graded the quality of the evidence using GRADE criteria. We included nineteen randomised controlled trials, with a total of 3123 patients (2547 above-knee, 576 below-knee bypass surgery). In total, nine graft types were compared (autologous vein, polytetrafluoroethylene (PTFE) with and without vein cuff, human umbilical vein (HUV), polyurethane (PUR), Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support). Studies differed in which graft types they compared and follow-up ranged from six months to 10 years.Above-knee bypassFor above-knee bypass, there was moderate-quality evidence that autologous vein grafts improve primary patency compared to prosthetic grafts by 60 months (Peto odds ratio (OR) 0.47, 95% confidence interval (CI

A numerical performance assessment of a commercial cardiopulmonary by-pass blood heat exchanger.

Science.gov (United States)

Consolo, Filippo; Fiore, Gianfranco B; Pelosi, Alessandra; Reggiani, Stefano; Redaelli, Alberto

2015-06-01

We developed a numerical model, based on multi-physics computational fluid dynamics (CFD) simulations, to assist the design process of a plastic hollow-fiber bundle blood heat exchanger (BHE) integrated within the INSPIRE(TM), a blood oxygenator (OXY) for cardiopulmonary by-pass procedures, recently released by Sorin Group Italia. In a comparative study, we analyzed five different geometrical design solutions of the BHE module. Quantitative geometrical-dependent parameters providing a comprehensive evaluation of both the hemo- and thermo-dynamics performance of the device were extracted to identify the best-performing prototypical solution. A convenient design configuration was identified, characterized by (i) a uniform blood flow pattern within the fiber bundle, preventing blood flow shunting and the onset of stagnation/recirculation areas and/or high velocity pathways, (ii) an enhanced blood heating efficiency, and (iii) a reduced blood pressure drop. The selected design configuration was then prototyped and tested to experimentally characterize the device performance. Experimental results confirmed numerical predictions, proving the effectiveness of CFD modeling as a reliable tool for in silico identification of suitable working conditions of blood handling medical devices. Notably, the numerical approach limited the need for extensive prototyping, thus reducing the corresponding machinery costs and time-to-market. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

40 CFR 63.307 - Standards for bypass/bleeder stacks.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for bypass/bleeder stacks. 63.307 Section 63.307 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... Standards for Coke Oven Batteries § 63.307 Standards for bypass/bleeder stacks. (a)(1) Except as otherwise...

The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

LENUS (Irish Health Repository)

Halpenny, M

2012-02-03

OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

Tidlige erfaringer med duplexovervågning af femoropopliteale og -krurale vene-bypass

DEFF Research Database (Denmark)

Nielsen, Tina G; von Jessen, Frants; Schroeder, T V

1993-01-01

Identification and correction of graft stenoses in femoropopliteal and -crural vein bypasses can prevent reconstruction failure. Sixty six consecutive vein bypasses entered a postoperative surveillance protocol, which implied clinical assessment, measurement of ankle blood pressure and duplex...... could not be reestablished. Of the 34 bypasses with normal duplex-scans only 2 (6%) thrombosed (p blood pressure measurement could reliably predict graft failure. This study indicates that duplex......-scanning effectively identifies grafts at risk and can be expected to improve long-term patency of infrainguinal vein bypasses....

Depression and Anxiety following Coronary Artery Bypass Graft: Current Indian Scenario

Directory of Open Access Journals (Sweden)

Suprakash Chaudhury

2016-01-01

Full Text Available Epidemiological studies have shown a high prevalence of coronary artery disease among the Indian Population. Due to increasing availability and affordability of tertiary care in many parts of India, carefully selected patients undergo coronary artery bypass surgery to improve cardiac function. However, the procedure is commonly associated with depression and anxiety which can adversely affect overall prognosis. The objective of this review is to highlight early identifiable symptoms of depression and anxiety following coronary artery bypass graft (CABG in Indian context so as to facilitate prompt intervention for better outcome. The current review was able to establish firm evidence in support of screening for depression and anxiety following CABG. Management of depression and anxiety following CABG is briefly reviewed.

Complications of Laparoscopic Retroperitoneal Sutureless and Clampless Aortobifemoral Bypass

Directory of Open Access Journals (Sweden)

B. Segers

Full Text Available : Introduction: This report describes our experience with early complications that occurred in two patients who underwent sutureless aortobifemoral bypass using the EndoVascular REtroperitoneoScopic Technique (EVREST. Report: Two patients who underwent EVREST for aortoiliac TASC D lesions experienced a dislocation of the proximal assembly. The first dislocation occurred four hours post-operatively and led to the death of the patient, and the second occurred during surgery and led to open conversion. Conclusion: As a result of these serious complications, we recommend the use of anchorage stitches while using an endograft connector in a sutureless aortobifemoral bypass. Keywords: Early complications, Sutureless, Clampless, Retroperitoneoscopy, Aortobifemoral bypass

Redesigned Gas Mass Flow Sensors for Space Shuttle Pressure Control System and Fuel Cell System

Science.gov (United States)

1996-01-01

A program was conducted to determine if a state of the art micro-machined silicon solid state flow sensor could be used to replace the existing space shuttle orbiter flow sensors. The rather aggressive goal was to obtain a new sensor which would also be a multi-gas sensor and operate over a much wider flow range and with a higher degree of accuracy than the existing sensors. Two types of sensors were tested. The first type was a venturi throat design and the second was a bypass design. The accuracy of venturi design was found to be marginally acceptable. The bypass sensor was much better although it still did not fully reach the accuracy goal. Two main problems were identified which would require further work.

Bypass of a nick by the replisome of bacteriophage T7.

Science.gov (United States)

Zhu, Bin; Lee, Seung-Joo; Richardson, Charles C

2011-08-12

DNA polymerase and DNA helicase are essential components of DNA replication. The helicase unwinds duplex DNA to provide single-stranded templates for DNA synthesis by the DNA polymerase. In bacteriophage T7, movement of either the DNA helicase or the DNA polymerase alone terminates upon encountering a nick in duplex DNA. Using a minicircular DNA, we show that the helicase · polymerase complex can bypass a nick, albeit at reduced efficiency of 7%, on the non-template strand to continue rolling circle DNA synthesis. A gap in the non-template strand cannot be bypassed. The efficiency of bypass synthesis depends on the DNA sequence downstream of the nick. A nick on the template strand cannot be bypassed. Addition of T7 single-stranded DNA-binding protein to the complex stimulates nick bypass 2-fold. We propose that the association of helicase with the polymerase prevents dissociation of the helicase upon encountering a nick, allowing the helicase to continue unwinding of the duplex downstream of the nick.

Cerebroprotective effect of piracetam in patients undergoing coronary bypass burgery.

Science.gov (United States)

Holinski, Sebastian; Claus, Benjamin; Alaaraj, Nour; Dohmen, Pascal Maria; Kirilova, Kremena; Neumann, Konrad; Uebelhack, Ralf; Konertz, Wolfgang

2008-11-01

Reduction of cognitive function is a possible side effect after cardiac surgery using cardiopulmonary bypass. We investigated the cerebroprotective effect of piracetam on cognitive performance in patients undergoing coronary artery bypass surgery under cardiopulmonary bypass. Patients scheduled for elective, primary and isolated coronary bypass surgery were randomised either to piracetam or placebo group. The study was performed in a double blind fashion. Patients received either 12 g piracetam or placebo at the beginning of the operation. Six neuropsychological subtests from the Syndrom Kurz Test and the Alzheimer's Disease Assessment Scale were performed preoperatively and on the third postoperative day. To assess the overall cognitive function and the degree of cognitive decline across all tests after surgery we combined the six test-scores by principal component analysis. A total number of 120 patients were enrolled into the study. Preoperative overall cognitive function were not significantly different between the groups. The postoperative combined score of the neuropsychological tests showed a deterioration of cognitive function in both groups (placebo-pre: -0.06+/-0.99 vs placebo-post: -1.38+/-1.11; ppiracetam-pre: 0.06+/-1.02 vs piracetam-post: -0.65+/-0.93; ppiracetam patients performed significantly better compared to the placebo patients after the operation and had a less decline of overall cognitive function (pPiracetam has a cerebroprotective effect in patients undergoing coronary artery bypass surgery with the use of cardiopulmonary bypass. It reduces an early postoperative substantial decline of neuropsychological abilities.

Obturator or "lateral" bypass in the management of infected vascular prostheses at the groin

Directory of Open Access Journals (Sweden)

Davidović Lazar B.

2002-01-01

Full Text Available The infection of the previously implanted vascular graft at the groin, is associated with great mortality and morbidity rate [1]. The authors present a retrospective study in which they analyzed management of infected vascular prostheses at the groin, using obturator bypass in 26 cases, and "lateral" bypass in 15 cases. The indications for obturator bypass reconstructions included: 20 infections of aorto-femoral grafts, two infected pse udoaneurysms in the groin after RTA of the superficial femoral artery, and 4 infections of iliac-femoral grafts. The indications for lateral bypass reconstructions were: infections after aorto-femoral reconstructions - 8 cases; infection after femora-popliteal reconstructions - 4 cases; infection after iliac-femoral reconstruction - 2 patients, and one infected pseudoaneurysm in the groin after RTA of the superficial femoral artery. In 3 subjects obturator bypass was performed using extraperitoneal approach while in other 23 patients transperitoneal approach was done by donor's artery. The obturator bypass was performed using a PTFE graft in 3 cases and Dacron graft in 23. The donor's artery used for obturator bypass was a noninfected proximal part of aortofemoral graft in 20 cases, and iliac artery in 6 patients. The superfical femoral artery was recipient artery for obturator bypass in 3 cases, deep femoral artery in one case, and above the knee popliteal artery in 22 cases (Figure 1. In two patients transperitoenal approach to donors artery for "lateral" bypass has been used, and in 13 cases extraperitoneal. The proximal noninfected part of aorto femoral graft was used as a donor's artery for lateral bypass in 8 patients, while common iliac artery in 7 subjects. In 5 cases recon structions were performed using PTFE grafts, in 3 using autologous saphenous vein grafts, and in 7 using Dacron grafts. The recipient artery for "lateral" bypass was deep femoral in 8 cases, superficial femoral in three patients and

Posttraumatic growth in post-surgical coronary artery bypass graft patients

Directory of Open Access Journals (Sweden)

Catherine A Waight

2015-02-01

Full Text Available Recent research in posttraumatic growth has been applied to people with life-threatening illnesses to optimise recovery. There is a lack of research exploring posttraumatic growth in coronary artery bypass graft patients. This article describes the recovery experience of 14 coronary artery bypass graft patients (13 males and 1 female at their first outpatient review post-surgery. Grounded theory analysis was used to develop a model of distinct and shared pathways to growth depending on whether patients were symptomatic or asymptomatic pre-coronary artery bypass graft. Outcomes of posttraumatic growth in this sample included action-based healthy lifestyle growth and two forms of cognitive growth: appreciation of life and new possibilities. The model of posttraumatic growth developed in this study may be helpful in guiding future research into promoting posttraumatic growth and behaviour change in coronary artery bypass graft patients.

Gastric bypass: why Roux-en-Y? A review of experimental data.

Science.gov (United States)

Collins, Brendan J; Miyashita, Tomoharu; Schweitzer, Michael; Magnuson, Thomas; Harmon, John W

2007-10-01

To highlight the clinical and experimental rationales that support why the Roux-en-Y limb is an important surgical principle for bariatric gastric bypass. We reviewed PubMed citations for open Roux-en-Y gastric bypass (RYGBP), laparoscopic RYGBP, loop gastric bypass, chronic alkaline reflux gastritis, and duodenoesophageal reflux. We reviewed clinical and experimental articles. Clinical articles included prospective, retrospective, and case series of patients undergoing RYGBP, laparoscopic RYGBP, or loop gastric bypass. Experimental articles that were reviewed included in vivo and in vitro models of chronic duodenoesophageal reflux and its effect on carcinogenesis. No formal data extraction was performed. We reviewed published operative times, lengths of stay, and anastomotic leak rates for laparoscopic RYGBP and loop gastric bypass. For in vivo and in vitro experimental models of duodenoesophageal reflux, we reviewed the kinetics and potential molecular mechanisms of carcinogenesis. Recent data suggest that laparoscopic loop gastric bypass, performed without the creation of a Roux-en-Y gastroenterostomy, is a faster surgical technique that confers similarly robust weight loss compared with RYGBP or laparoscopic RYGBP. In the absence of a Roux limb, the long-term effects of chronic alkaline reflux are unknown. Animal models and in vitro analyses of chronic alkaline reflux suggest a carcinogenic effect.

Esophageal bypass after failed chemoradiotherapy for unresectable esophageal cancer

International Nuclear Information System (INIS)

Matono, Satoru; Tanaka, Toshiaki; Mori, Naoki; Nagano, Takeshi; Fujita, Hiromasa; Shirouzu, Kazuo

2013-01-01

Esophageal stenosis and/or fistula often occur after chemoradiotherapy (CRT) for unresectable esophageal cancer. In such patients, an esophageal stent can help achieve oral intake. However an esophageal stent cannot be inserted where there is complete stenosis or where the tumor is located. In such cases, esophageal bypass surgery may be necessary. Here, we investigated the clinical characteristics and outcomes in patients who underwent esophageal bypass surgery in our institution. We reviewed 10 cases of esophageal bypass surgery (gastric tube in 8 cases, colon in 2 cases) after CRT for unresectable esophageal cancer, between 2001 and 2009. There were 5 of stenosis-only cases, 4 fistula-only cases, and 1 case of stenosis and fistula. There were postoperative complications in 5 cases (50%), and all these were treated conservatively and healed. The median survival from surgery to peroral intake was 20 days (range 9-90 days), and the median survival after starting peroral intake was 130 days (range 48-293 days). Esophageal bypass surgery can achieve good performance status and improve peroral intake. (author)

Emergency bypass post percutaneous atrial ablation: a case report.

LENUS (Irish Health Repository)

Hargrove, M

2010-11-01

A 34-year-old male undergoing percutaneous atrial ablation procedure for paroxysmal fibrillation required emergency sternotomy for cardiac tamponade. The patient had been anticoagulated and had received plavix and aspirin prior to and during the ablation procedure. Seven units of red cell concentrate had been transfused in the cardiac catherisation laboratory. On arrival in theatre, the patient was hypotensive, but was awake on induction of anaesthesia. No recordable blood pressure with non-invasive monitoring was observed. A sternotomy was immediately performed and, on evacuation of the pericardium, a bleeding site was not visible. The patient was commenced on cardiopulmonary bypass. Bleeding site was identified and the defect closed. The patient was weaned from cardiopulmonary bypass with minimal inotropic support and made an uneventful recovery. Bypass time was 38 minutes. A literature review showed a 1% incidence of post-ablation bleeding(1). The incidence of reverting to bypass for such an event has not been reported previously. During these procedures, it might be wise to have the cardiothoracic team notified while atrial ablation procedures are being performed in the cardiac catheterization laboratory.

Analgesic Treatment in Laparoscopic Gastric Bypass Surgery

DEFF Research Database (Denmark)

Andersen, Lars P H; Werner, Mads U; Rosenberg, Jacob

2014-01-01

This review aimed to present an overview of the randomized controlled trials investigating analgesic regimens used in laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery. Literature search was performed in PubMed and EMBASE databases in August 2013 in accordance to PRISMA guidelines. The litera......This review aimed to present an overview of the randomized controlled trials investigating analgesic regimens used in laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery. Literature search was performed in PubMed and EMBASE databases in August 2013 in accordance to PRISMA guidelines...

A new beating-heart off-pump coronary artery bypass grafting training model

NARCIS (Netherlands)

Bouma, Wobbe; Kuijpers, Michiel; Bijleveld, Aanke; De Maat, Gijs E.; Koene, Bart M.; Erasmus, Michiel E.; Natour, Ehsan; Mariani, Massimo A.

OBJECTIVES: Training models are essential in mastering the skills required for off-pump coronary artery bypass grafting (OPCAB). We describe a new, high-fidelity, effective and reproducible beating-heart OPCAB training model in human cadavers. METHODS: Human cadavers were embalmed according to the

Rankine cycle condenser pressure control using an energy conversion device bypass valve

Science.gov (United States)

Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

2014-04-01

The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

On-Pump Versus Off-Pump Coronary Artery Bypass Surgery in Elderly Patients

DEFF Research Database (Denmark)

Houlind, Kim; Kjeldsen, Bo Juul; Madsen, Susanne Nørgaard

2012-01-01

BACKGROUND: Conventional coronary artery bypass grafting performed with the use of cardiopulmonary bypass is a well-validated treatment for patients with ischemic heart disease. Off-pump coronary artery bypass grafting (OPCAB) has been suggested to reduce the number of perioperative complications......, especially in elderly patients. METHODS AND RESULTS: In a multicenter, randomized trial, we assigned 900 patients >70 years of age to conventional coronary artery bypass grafting or OPCAB surgery. After 30 days, a blinded end-point committee assessed whether a combined end point of death, stroke...... experiencing the combined end point within 30 days was 10.2% for conventional coronary artery bypass grafting and 10.7% for OPCAB. Implied risk difference of 0.4% (with a 95% confidence interval, -3.6 to 4.4) showed nonsignificance in a standard test for equality (P=0.83) and for noninferiority...

Angiographyc and intraoperative assessment of the blood flow in infrainguinal arterial reconstruction; Angiografska i intraoperativna itsenka na kryvotoka pri arterialni rekonstruktsii pod ingvinalniya ligament

Energy Technology Data Exchange (ETDEWEB)

Cheshmedzhiev, M; Jordanov, E; Yordanov, M; Kovacheva, N [Department of Vascular Surgery, University Hospital St. Marina, Varna (Bulgaria); Velinov, T [Department of Diagnostic Imaging, University Hospital St. Marina, Varna (Bulgaria)

2011-07-01

The aim of this study is to define the practical application of the modified system for angiographic assessment of the run-off arteries after reconstruction below the inguinal ligament suggested by Schwierz T. 137 patients with infrainguinal arterial reconstructions were followed up for a period of 1 year. The blood volume was measured distally from the distal graft anastomosis by means of flow meter (VeriQ, Medistim, Oslo, Norway). The flowmetry was performed before and after a 5-minute Prostavasin or llomedin intragraft infusion, causing peripheral vasodilatation. The data was compared with the minimal expected debit which was assessed according to the Schwirz system. During the follow up period in the group of the non properly functioning bypasses we registered lack of coincidence in 37% between the preoperatively assessed and the intraoperatively measured minimal blood flow concerning the compromised bypasses. In the group of the properly functioning bypasses the lack of coincidence was only 6% probably due to subjective false assessment of minor collaterals. Taking into consideration the subjective pattern of the angiographic assessment system and the importance of the high quality angiographic imaging we believe that the preoperatively assessed expected blood flow is not applicable in means of long term prognosis but may be used as an additional indicator for the condition of the run-off arteries as well as the short term results of the operative treatment.

A case report and brief review of the literature on bilateral retinal infarction following cardiopulmonary bypass for coronary artery bypass grafting

Directory of Open Access Journals (Sweden)

Trethowan Brian A

2011-11-01

Full Text Available Abstract Postoperative visual loss is a devastating perioperative complication. The commonest aetiologies are anterior ischaemic optic neuropathy (AION, posterior ischaemic optic neuropathy (PION, and central retinal artery occlusion (CRAO. These appear to be related to certain types of operation, most commonly spinal and cardiac bypass procedures; with the rest divided between: major trauma causing excessive blood loss; head/neck and nasal or sinus surgery; major vascular procedures (aortic aneurysm repair, aorto-bifemoral bypass; general surgery; urology; gynaecology; liposuction; liver transplantation and duration of surgery. The non-surgical risk factors are multifactorial: advanced age, prolonged postoperative anaemia, positioning (supine v prone, alteration of venous drainage of the retina, hypertension, smoking, atherosclerosis, hyperlipidaemia, diabetes, hypercoagulability, hypotension, blood loss and large volume resuscitation. Other important cardiac causes are septic emboli from bacterial endocarditis and emboli caused by atrial myxomata. The majority of AION cases occur during CPB followed by head/neck surgery and prone spine surgery. CPB is used to allow coronary artery bypass grafting on a motionless heart. It has many side-effects and complications associated with its use and we report here a case of bilateral retinal infarction during routine coronary artery bypass grafting in a young male patient with multiple risk factors for developing this complication despite steps to minimise its occurrence.

Combination of FVIII and by-passing agent potentiates in vitro thrombin production in haemophilia A inhibitor plasma.

Science.gov (United States)

Klintman, Jenny; Astermark, Jan; Berntorp, Erik

2010-11-01

The by-passing agents, recombinant activated factor VII (rFVIIa) and activated prothrombin complex concentrate (APCC), are important tools in the treatment of patients with haemophilia A and high-responding inhibitory antibodies. It has been observed clinically that in some patients undergoing immune tolerance induction the bleeding frequency decreases, hypothetically caused by a transient haemostatic effect of infused FVIII not measurable ex vivo. We evaluated how by-passing agents and factor VIII (FVIII) affect thrombin generation (TG) in vitro using plasma from 11 patients with severe haemophilia A and high titre inhibitors. Samples were spiked with combinations of APCC, rFVIIa and five different FVIII products. Combination of APCC and FVIII showed a synergistic effect in eliciting TG (Pproducts. When rFVIIa and FVIII were combined the interaction between the preparations was found to be additive. APCC and rFVIIa were then combined without FVIII, resulting in an additive effect on thrombin production. Each product separately increased TG above baseline. In conclusion, the amount of thrombin formed in vitro by adding a by-passing agent, was higher in the presence of FVIII. Our findings support the use of FVIII in by-passing therapy to optimize the haemostatic effect. © 2010 Blackwell Publishing Ltd.

Experimental Investigation on Cross Flow of Wedge-shaped Gap in the core of Prismatic VHTR

International Nuclear Information System (INIS)

Lee, Jeong Hun; Park, Goon Cherl; Cho, Hyoung Kyu; Yoon, Su Jong

2014-01-01

The core of the PMR type reactor consists of assemblies of hexagonal graphite blocks. The graphite blocks have lots of advantages for neutron economy and high temperature structural integrity. The height and flat-to-flat width of fuel bock are 793 mm and 360 mm, respectively. Each block has 108 coolant channels of which the diameter is 16 mm. And there are gaps between blocks not only vertically but also horizontally for reloading of the fuel elements. The vertical gap induces the bypass flow and through the horizontal gap the cross flow is formed. Since the complicated flow distribution occurs by the bypass flow and cross flow, flow characteristics in the core of the PMR reactor cannot be treated as a simple pipe flow. The fuel zone of the PMR core consists of multiple layers of fuel blocks. The shape change of the fuel blocks could be caused by the thermal expansion and fast-neutron induced shrinkage. It could make different axial shrinkage of fuel block and this leads to wedge-shaped gaps between two stacked fuel blocks. The cross flow is often considered as a leakage flow through the horizontal gap between stacked fuel blocks and it complicates the flow distribution in the reactor core by connecting the coolant channel and the bypass gap. Moreover, the cross flow could lead to uneven coolant distribution and consequently cause superheating of individual fuel element zones with increased fission product release. Since the core cross flow has a negative impact on safety and efficiency of VHTR, core cross flow phenomena have to be investigated to improve the core thermal margin of VHTR. To develop the cross flow loss coefficient model for determination of the flow distribution for PMR core analysis codes, study on cross flow for PMR200 core is essential. In particular, to predict the amount of flow through the cross flow gap, obtaining accurate flow loss coefficient is important. In this study, the full-scale cross flow experimental facility was constructed to

Bypass of a Nick by the Replisome of Bacteriophage T7*

Science.gov (United States)

Zhu, Bin; Lee, Seung-Joo; Richardson, Charles C.

2011-01-01

DNA polymerase and DNA helicase are essential components of DNA replication. The helicase unwinds duplex DNA to provide single-stranded templates for DNA synthesis by the DNA polymerase. In bacteriophage T7, movement of either the DNA helicase or the DNA polymerase alone terminates upon encountering a nick in duplex DNA. Using a minicircular DNA, we show that the helicase·polymerase complex can bypass a nick, albeit at reduced efficiency of 7%, on the non-template strand to continue rolling circle DNA synthesis. A gap in the non-template strand cannot be bypassed. The efficiency of bypass synthesis depends on the DNA sequence downstream of the nick. A nick on the template strand cannot be bypassed. Addition of T7 single-stranded DNA-binding protein to the complex stimulates nick bypass 2-fold. We propose that the association of helicase with the polymerase prevents dissociation of the helicase upon encountering a nick, allowing the helicase to continue unwinding of the duplex downstream of the nick. PMID:21701044

Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

Energy Technology Data Exchange (ETDEWEB)

Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

2014-02-15

The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

A Delphi Consensus of the Crucial Steps in Gastric Bypass and Sleeve Gastrectomy Procedures in the Netherlands.

Science.gov (United States)

Kaijser, Mirjam A; van Ramshorst, Gabrielle H; Emous, Marloes; Veeger, Nic J G M; van Wagensveld, Bart A; Pierie, Jean-Pierre E N

2018-04-09

Bariatric procedures are technically complex and skill demanding. In order to standardize the procedures for research and training, a Delphi analysis was performed to reach consensus on the practice of the laparoscopic gastric bypass and sleeve gastrectomy in the Netherlands. After a pre-round identifying all possible steps from literature and expert opinion within our study group, questionnaires were send to 68 registered Dutch bariatric surgeons, with 73 steps for bypass surgery and 51 steps for sleeve gastrectomy. Statistical analysis was performed to identify steps with and without consensus. This process was repeated to reach consensus of all necessary steps. Thirty-eight participants (56%) responded in the first round and 32 participants (47%) in the second round. After the first Delphi round, 19 steps for gastric bypass (26%) and 14 for sleeve gastrectomy (27%) gained full consensus. After the second round, an additional amount of 10 and 12 sub-steps was confirmed as key steps, respectively. Thirteen steps in the gastric bypass and seven in the gastric sleeve were deemed advisable. Our expert panel showed a high level of consensus expressed in a Cronbach's alpha of 0.82 for the gastric bypass and 0.87 for the sleeve gastrectomy. The Delphi consensus defined 29 steps for gastric bypass and 26 for sleeve gastrectomy as being crucial for correct performance of these procedures to the standards of our expert panel. These results offer a clear framework for the technical execution of these procedures.

Impairment of neuropsychological function in patients with hemodynamic cerebral ischemia and efficacy of bypass surgery

International Nuclear Information System (INIS)

Sasoh, Masayuki

1999-01-01

In order to evaluate the relation between neuropsychological functions and hemodynamic cerebral ischemia, the author analyzed neuropsychological examination and the cerebral blood flow and metabolism of patients before and after bypass surgery. Twenty-five patients were defined by clinical and laboratory criteria as suffering from hemodynamic cerebral ischemia. All patients had one or more episodes of focal cerebral ischemia due to unilateral internal carotid or middle cerebral artery occlusion. Computerized tomography scans either were normal or showed evidence of watershed infarction. Based on these criteria, superficial temporal artery-proximal middle cerebral artery anastomosis was performed. The baseline cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMRO 2 ) and cerebrovascular reserve capacity (CVRC) were studied using positron emission computerized tomography (PET) and the acetazolamide test. Neuropsychological evaluations including Hasegawa Dementia Scale-Revised, Mini-Mental State and Wechsler Adult Intelligence Scale-Revised (WAIS-R), and PET study were completed one month after the last ischemic event and 3-6 months after the operation. A significant negative correlation was observed between OEF and neuropsychological functions. Postoperative neuropsychological functions showed significant improvement. Significant correlations were observed for ΔWAIS-R (preoperative WAIS-R postoperative WAIS-R) versus preoperative CMRO 2 (r=0.52), for ΔWAIS-R versus preoperative OEF (r=0.47). In view of these findings, the author concludes that elevation of OEF impairs neuropsychological functions and bypass surgery improves neuropsychological functions in patients with normal CMRO 2 and elevated OEF. (author)

Femoro-Supragenicular Popliteal Bypass with a Bridging Stent Graft in a Diffusely Diseased Distal Target Popliteal Artery: Alternative to Below-Knee Popliteal Polytetrafluoroethylene Bypass

Directory of Open Access Journals (Sweden)

Joung Hun Byun

2017-10-01

Full Text Available Background: Lesions in distal target arteries hinder surgical bypass procedures in patients with peripheral arterial occlusive disease. Methods: Between April 2012 and October 2015, 16 patients (18 limbs with lifestyle- limiting claudication (n=12 or chronic critical limb ischemia (n=6 underwent femoral–above-knee (AK polytetrafluoroethylene (PTFE bypass grafts with a bridging stent graft placement between the distal target popliteal artery and the PTFE graft. Ring-supported PTFE grafts were used in all patients with no available vein for graft material. Follow-up evaluations assessed clinical symptoms, the ankle-brachial index, ultrasonographic imaging and/or computed tomography angiography, the primary patency rate, and complications. Results: All procedures were successful. The mean follow-up was 12.6 months (range, 11 to 14 months, and there were no major complications. The median baseline ankle-brachial index of 0.4 (range, 0.2 to 0.55 significantly increased to 0.8 (range, 0.5 to 1.0 at 12 months (p＜0.01. The primary patency rate at 12 months was 83.3%. The presenting symptoms resolved within 2 weeks. Conclusion: In AK bypasses with a diffusely diseased distal target popliteal artery or when below-knee (BK bypass surgery is impossible, this procedure could be clinically effective and safe when used as an alternative to femoral-BK bypass surgery.

Severe scurvy after gastric bypass surgery and a poor postoperative diet

DEFF Research Database (Denmark)

Hansen, Esben P K; Metzsche, Carsten; Henningsen, Emil

2012-01-01

After bariatric gastric bypass surgery patients are at risk of developing micronutrient deficiencies. If gastric bypass surgery is followed by a vitamin deficient diet the patients have a risk of developing vitamin-C deficiency. When spontaneous ecchymosis is observed in the skin, in at......-risk patients, scurvy must be considered. When treated with large doses of vitamin-C the symptoms of scurvy rapidly improve even if the patient has developed multiple organ dysfunction syndrome. KEYWORDS: Scurvy; Gastric bypass surgery; Multiorgan dysfunction....

Transfusion requirements in elective cardiopulmonary bypass surgery patients

DEFF Research Database (Denmark)

Sivapalan, Praleene; Bäck, Anne Caroline; Ostrowski, Sisse Rye

2017-01-01

Managing haemostasis in patients undergoing cardiopulmonary bypass (CPB) surgery remains a challenge. There is no established laboratory test to predict transfusion requirements in cardiac surgery. We investigated whether preoperative Thromboelastography (TEG) with Platelet Mapping Assay (PMA......) or Multiple Electrode Aggrometry (MEA) could predict transfusion requirements in patients undergoing elective coronary artery bypass grafting (CABG) or combined CABG with aortic or mitral valve replacement. We prospectively investigated 199 patients undergoing elective CABG or combined procedures. PMA and MEA...

Severe hypoglycaemia post-gastric bypass requiring partial pancreatectomy

DEFF Research Database (Denmark)

Patti, M E; McMahon, G; Mun, E C

2005-01-01

AIMS/HYPOTHESIS: Postprandial hypoglycaemia following gastric bypass for obesity is considered a late manifestation of the dumping syndrome and can usually be managed with dietary modification. We investigated three patients with severe postprandial hypoglycaemia and hyperinsulinaemia unresponsive...... was assessed in all three patients. RESULTS: All three patients had evidence of severe postprandial hyperinsulinaemia and hypoglycaemia. In one patient, reversal of gastric bypass was ineffective in reversing hypoglycaemia. All three patients ultimately required partial pancreatectomy for control...

Oil Bypass Filter Technology Performance Evaluation - January 2003 Quarterly Report

Energy Technology Data Exchange (ETDEWEB)

Laurence R. Zirker; James E. Francfort

2003-01-01

This report details the initial activities to evaluate the performance of the oil bypass filter technology being tested by the Idaho National Engineering and Environmental Laboratory (INEEL) for the U.S. Department of Energy's FreedomCAR & Vehicle Technologies Program. Eight full-size, four-cycle diesel-engine buses used to transport INEEL employees on various routes have been equipped with oil bypass systems from the puraDYN Corporation. Each bus averages about 60,000 miles a year. The evaluation includes an oil analysis regime to monitor the presence of necessary additives in the oil and to detect undesirable contaminants. Very preliminary economic analysis suggests that the oil bypass system can reduce life-cycle costs. As the evaluation continues and oil avoidance costs are quantified, it is estimated that the bypass system economics may prove increasingly favorable, given the anticipated savings in operational costs and in reduced use of oil and waste oil avoidance.

Is phonology bypassed in normal or dyslexic development?

Science.gov (United States)

Pennington, B F; Lefly, D L; Van Orden, G C; Bookman, M O; Smith, S D

1987-01-01

A pervasive assumption in most accounts of normal reading and spelling development is that phonological coding is important early in development but is subsequently superseded by faster, orthographic coding which bypasses phonology. We call this assumption, which derives from dual process theory, the developmental bypass hypothesis. The present study tests four specific predictions of the developmental bypass hypothesis by comparing dyslexics and nondyslexics from the same families in a cross-sectional design. The four predictions are: 1) That phonological coding skill develops early in normal readers and soon reaches asymptote, whereas orthographic coding skill has a protracted course of development; 2) that the correlation of adult reading or spelling performance with phonological coding skill is considerably less than the correlation with orthographic coding skill; 3) that dyslexics who are mainly deficient in phonological coding skill should be able to bypass this deficit and eventually close the gap in reading and spelling performance; and 4) that the greatest differences between dyslexics and developmental controls on measures of phonological coding skill should be observed early rather than late in development.None of the four predictions of the developmental bypass hypothesis were upheld. Phonological coding skill continued to develop in nondyslexics until adulthood. It accounted for a substantial (32-53 percent) portion of the variance in reading and spelling performance in adult nondyslexics, whereas orthographic coding skill did not account for a statistically reliable portion of this variance. The dyslexics differed little across age in phonological coding skill, but made linear progress in orthographic coding skill, surpassing spelling-age (SA) controls by adulthood. Nonetheless, they didnot close the gap in reading and spelling performance. Finally, dyslexics were significantly worse than SA (and Reading Age [RA]) controls in phonological coding skill

Perioperative risk factors for prolonged mechanical ventilation and tracheostomy in women undergoing coronary artery bypass graft with cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Zahra S Faritous

2011-01-01

Full Text Available Background: Prolonged mechanical ventilation is an important recognized complication occurring during cardiovascular surgery procedures. This study was done to assess the perioperative risk factors related to postoperative pulmonary complications and tracheostomy in women undergoing coronary artery bypass graft with cardiopulmonary bypass. Methods: It was a retrospective study on 5,497 patients, including 31 patients with prolonged ventilatory support and 5,466 patients without it; from the latter group, 350 patients with normal condition (extubated in 6-8 hours without any complication were selected randomly. Possible perioperative risk factors were compared between the two groups using a binary logistic regression model. Results: Among the 5,497 women undergoing coronary artery bypass graft (CABG, 31 women needed prolonged mechanical ventilation (PMV, and 15 underwent tracheostomy. After logistic regression, 7 factors were determined as being independent perioperative risk factors for PMV. Discussion: Age ≥70 years old, left ventricular ejection fraction (LVEF ≤30%, preexisting respiratory or renal disease, emergency or re-do operation and use of preoperative inotropic agents are the main risk factors determined in this study on women undergoing CABG.

Axillary artery to left anterior descending coronary artery bypass with an externally stented graft: a technical report

Directory of Open Access Journals (Sweden)

Salvador Loris

2008-02-01

Full Text Available Abstract With the proliferation of minimally invasive cardiac surgery a number of alternative inflow sites for coronary artery bypass grafting have been utilized, especially in higher risk patients. The use of axillary-coronary artery bypass is a safe and effective alternative especially in the case of patients requiring redo coronary revascularization. However, the length and convoluted course of the axillary-coronary vein graft makes is susceptible to twisting, trauma and neointimal hyperplasia. We therefore report a case of an axillary-coronary artery bypass in a high risk patient in which a Dacron conduit was used to externally support and protect the vein graft to the left anterior descending artery. Surgical technique and considerations are presented and discussed.

Testing of high current by-pass diodes for the LHC magnet quench protection

International Nuclear Information System (INIS)

Berland, V.; Hagedorn, D.; Rodriguez-Mateos, F.

1996-01-01

Within the framework of the Large Hadron Collider (LHC) R and D program, CERN is performing experiments to establish the current carrying capability of irradiated diodes at liquid Helium temperatures for the superconducting magnet protection. Even if the diodes are degraded by radiation dose and neutron fluence, they must be able to support the by-pass current during a magnet quench and the de-excitation of the superconducting magnet ring. During this discharge, the current in the diode reaches a maximum value up to 13 kA and decreased with an exponential time constant of 100 s. Two sets of 75 mm wafer diameter epitaxial diodes, one irradiated and one non-irradiated, were submitted to this experiment. The irradiated diodes have been exposed to radiation in the accelerator environment up to 20 kGy and then annealed at room temperature. After the radiation exposure the diodes had shown a degradation of forward voltage of 50% which reduced to about 14% after the thermal annealing. During the long duration high current tests, one of the diodes was destroyed and the other two irradiated diodes showed a different behavior compared with non-irradiated diodes

Renal tubular acidosis secondary to jejunoileal bypass for morbid obesity

DEFF Research Database (Denmark)

Schaffalitzky de Muckadell, O B; Ladefoged, Jens; Thorup, Jørgen Mogens

1985-01-01

Renal handling of acid and base was studied in patients with persistent metabolic acidosis 3-9 years after jejunoileal bypass for morbid obesity. Excretion of acid was studied before and after intravenous infusion of NH4Cl and excretion of bicarbonate after infusion of NaHCO3. Bypass patients...

Heart bypass surgery - minimally invasive

Science.gov (United States)

... MIDCAB; Robot-assisted coronary artery bypass; RACAB; Keyhole heart surgery; CAD - MIDCAB; Coronary artery disease - MIDCAB ... To perform this surgery: The heart surgeon will make a 3- to 5-inch (8 to 13 centimeters) surgical cut in the left part of your chest ...

Development trend of high bypass ratio turbofan engines. Ko baipasu hi tabo fan engine no kaihatsu doko

Energy Technology Data Exchange (ETDEWEB)

Tonomura, Y [Mitsubishi Heavy Industries Ltd., Tokyo (Japan)

1994-03-10

The turbofan engines for private aircrafts have come to have a high bypass ratio because a performance improvement is always requested. Because a turbofan engine is always required for a thrust reinforcement to correspond the stretch and weight increase of a fuselage after acquiring a type approval, making them a series to cover a certain thrust range becomes necessary. The concrete methods to reinforce a thrust are being achieved by an increase of fan diameter, a partial modification of high pressure compressor, a temperature rise of high pressure turbine inlet, a stage number increase of low pressure turbine, and a combination of these items just mentioned above. The PW 4000 series, CF6 series and RB211 series currently under production are being reinforced in a thrust by these methods. In this paper, as the representatives of some turbofan engines incorporating the most advanced technologies, as for 3 kinds of the large scale turbofan engine presently under development for the B777, namely GE90, PW4084, and TRENT800, their distinctive futures are summarized. 25 figs., 1 tab.

Resveratrol combined with total flavones of hawthorn alleviate the endothelial cells injury after coronary bypass graft surgery.

Science.gov (United States)

Zhu, Ying; Feng, Bing; He, Songmin; Su, Zuqing; Zheng, Guangjuan

2018-02-01

To explore the preventive and therapeutic effects of Resveratrol combined with total flavones of hawthorn, compatibility of traditional Chinese medicines, on the endothelial cells injury after artery bypass graft surgery. The animal model of coronary artery bypass grafting (CABG) was prepared by transplanting a segment of autologous jugular vein onto the transected common carotid artery in rabbits. After CABG surgery, the rabbits were administrated with saline (model group), aspirin (Aspirin group), resveratrol (Res group), total flavones of hawthorn (Haw group) and resveratrol combined with total flavones of hawthorn (Res+Haw group) once a day for eight weeks, respectively. Eight weeks later, the grafting arteries from all group were obtained for the pathomorphism observation, peripheral blood was collected to detect circulating endothelial cells (CECs) by flow cytometry. And the concentration of albumen and mRNA of ICAM-1 in the serum were measured by western blot and quantitative real-time polymerase chain reaction, respectively. Compared with the model group, the level of CECs density and the expressions of albumen and mRNA of ICAM-1 were significantly decreased in the aspirin,resveratrol,total flavones of hawthorn and resveratrol combined with total flavones of hawthorn groups (P Resveratrol combined with total flavones of hawthorn could protect the endothelial cells after coronary artery bypass graft. Copyright © 2018 Elsevier GmbH. All rights reserved.

Temporary diabetes insipidus in 2 men after on-pump coronary artery bypass grafting.

Science.gov (United States)

Uyar, Ihsan Sami; Sahin, Veysel; Akpinar, Besir; Yurtman, Volkan; Abacilar, Feyzi; Okur, Faik Fevzi; Ates, Mehmet

2013-01-01

Many complications have been reported after cardiopulmonary bypass. A common physiologic change during the early postoperative period after cardiopulmonary bypass is increased diuresis. In patients whose urine output is increased, postoperative diabetes insipidus can develop, although reports of this are rare. We present the cases of 2 patients who underwent on-pump coronary artery bypass grafting (with cardiopulmonary bypass). Each was diagnosed with diabetes insipidus postoperatively: a 54-year-old man on the 3rd day, and a 66-year-old man on the 4th day. Each patient recovered from the condition after 6 hours of intranasal therapy with synthetic vasopressin (antidiuretic hormone). The diagnosis of diabetes insipidus should be considered in patients who produce excessive urine early after cardiac surgery in which cardiopulmonary bypass has been used.

Cardiopulmonary bypass: development of John Gibbon's heart-lung machine

OpenAIRE

Passaroni, Andréia Cristina; Silva, Marcos Augusto de Moraes; Yoshida, Winston Bonetti

2015-01-01

AbstractObjective:To provide a brief review of the development of cardiopulmonary bypass.Methods:A review of the literature on the development of extracorporeal circulation techniques, their essential role in cardiovascular surgery, and the complications associated with their use, including hemolysis and inflammation.Results:The advancement of extracorporeal circulation techniques has played an essential role in minimizing the complications of cardiopulmonary bypass, which can range from vari...

Dacron or PTFE for above-knee femoropopliteal bypass. a multicenter randomised study

DEFF Research Database (Denmark)

Jensen, L P; Lepäntalo, M; Fossdal, J E

2007-01-01

To compare polytetrafluorethylene (PTFE) and polyester grafts (Dacron) for above knee femoropopliteal bypass.......To compare polytetrafluorethylene (PTFE) and polyester grafts (Dacron) for above knee femoropopliteal bypass....

Evolution of elderly patients who underwent cardiac surgery with cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Alain Moré Duarte

2016-01-01

Full Text Available Introduction: There is a steady increase in the number of elderly patients with severe cardiovascular diseases who require a surgical procedure to recover some quality of life that allows them a socially meaningful existence, despite the risks.Objectives: To analyze the behavior of elderly patients who underwent cardiac surgery with cardiopulmonary bypass.Method: A descriptive, retrospective, cross-sectional study was conducted with patients over 65 years of age who underwent surgery at the Cardiocentro Ernesto Che Guevara, in Santa Clara, from January 2013 to March 2014.Results: In the study, 73.1% of patients were men; and there was a predominance of subjects between 65 and 70 years of age, accounting for 67.3%. Coronary artery bypass graft was the most prevalent type of surgery and had the longest cardiopulmonary bypass times. Hypertension was present in 98.1% of patients. The most frequent postoperative complications were renal dysfunction and severe low cardiac output, with 44.2% and 34.6% respectively.Conclusions: There was a predominance of men, the age group of 65 to 70 years, hypertension, and patients who underwent coronary artery bypass graft with prolonged cardiopulmonary bypass. Renal dysfunction was the most frequent complication.

Unstable fluid flow in a water-cooled heating channel

International Nuclear Information System (INIS)

Delayre, R.; Saunier, J.P.

1961-01-01

Experimental investigations of the instable behavior of a pressurized water flow in forced convection in a heating channel, with subcooled or bulk boiling have been carried. Tests were conducted at 1140, 850 and 570 psi. The test section was 35 in. high, surmounted by a 25.4 in. riser, these sections were by-passed by a pipe where the flow was between 1 and 4 times the flow in the test section. The water velocity (in the test section) was between 1.6 and 6.6 ft/s. Under certain conditions oscillations with a period of several seconds and perfectly stable have been observed. A mathematical model has been defined and a good agreement obtained for the main characteristics of the oscillations. It seems that the dimensions of the riser have a determining effect: the inception of bulk boiling gives an important variation of the driving head which can generate oscillations due to the non-zero delay for the system to reach its equilibrium. (author) [fr

Power plant and system for accelerating a cross compound turbine in such plant, especially one having an HTGR steam supply

International Nuclear Information System (INIS)

Jaegtnes, K.O.; Braytenbah, A.S.

1979-01-01

In accordance with the present invention, a power plant includes a steam source to generate superheat and reheat steam which flows through a turbine-generator and an associated bypass system. A high-pressure and an intermediate-pressure turbine portion drive a first electrical generating means, and a low-pressure turbine portion drives a second electrical generating means. A first flow of superheat steam flows through the high-pressure portion, while a second flow of reheat steam flows through the intermediate and low-pressure portions in succession. Provision is made for bypassing steam around the turbine portions; in particular, one bypass means permits a flow of superheat steam from the steam source to the exhaust of the high-pressure portion, and another bypass means allows reheated steam to pass from the source to the exhaust of the low-pressure portion. The first and second steam flows are governed independently. While one of such flows is varied for purposes of controlling the rotational speed of the first generating means according to a desired speed, the other flow is varied to regulate a power plant variable at its desired level. (author)

Conversion of Aircraft Dual-flow Turbojet into Peak Power Plant

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G. A. Shafikov

2017-01-01

Full Text Available The paper is aimed at considering the aircraft engine conversion into peak or short-used energy unit, which is relevant for the task of developing the northern regions of the Russian Federation. The three-shaft turbojet engine with a twelve-stage compressor and a four-stage turbine is adopted as an aircraft engine under consideration. The afterburner with a block of jet nozzles is removed from the gas generator module, and a heating chamber is set at the outlet of the by-pass duct to raise electric power of engine and not complicate the construction by the presence of a mixing chamber. In addition, the heating chamber serves to equalize the total pressure and flow temperature in the section before the free turbine and allows the use of a short adapter between the gas generator module and the free turbine, which reduces the loss of total pressure. Then a free turbine and a diffuser with an exhaust device are installed. The output shaft of the power turbine is connected by means of a coupling to an alternating current (a. c. generator or other special load.To find the parameters of the plant, a calculation was made in which the initial data were taken, namely a gas temperature in front of the turbine of 1530 K (the gas temperature in front of the turbine is reduced by 100 K in order to prolong the engine life; therefore, the gas temperature before the turbine was 1630 K; air flow of 364 kg/s; bypass ratio of 1.36 (the ratio of the air flow passing through the bypass duct to the air flow entering the core. As a result, it consumes 0.296 kg / (kWh (fuel-aviation kerosene and a power capacity of 78.5 MW. For the received value of capacity the ТЗФП-80-2У3 a. c. electric generator has been chosen as the load. As a result, the power plant, equipped with a converted engine and electric generator, has an electric power of 77.3 MW and an efficiency of 27.8%.To assess the effect of introduced preheating chamber on the parameters of the gas turbine

A simple technique can reduce cardiopulmonary bypass use during lung transplantation

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Marcos N. Samano

2016-04-01

Full Text Available Cardiopulmonary bypass causes an inflammatory response and consumption of coagulation factors, increasing the risk of bleeding and neurological and renal complications. Its use during lung transplantation may be due to pulmonary hypertension or associated cardiac defects or just for better exposure of the pulmonary hilum. We describe a simple technique, or open pericardium retraction, to improve hilar exposure by lifting the heart by upward retraction of the pericardial sac. This technique permits lung transplantation without cardiopulmonary bypass when bypass use is recommended only for better exposure.

Flow characteristics of Korea multi-purpose research reactor

Energy Technology Data Exchange (ETDEWEB)

Heonil Kim; Hee Taek Chae; Byung Jin Jun; Ji Bok Lee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-09-01

The construction of Korea Multi-purpose Research Reactor (KMRR), a 30 MW{sub th} open-tank-in-pool type, is completed. Various thermal-hydraulic experiments have been conducted to verify the design characteristics of the KMRR. This paper describes the commissioning experiments to determine the flow distribution of KMRR core and the flow characteristics inside the chimney which stands on top of the core. The core flow is distributed to within {+-}6% of the average values, which is sufficiently flat in the sense that the design velocity in the fueled region is satisfied. The role of core bypass flow to confine the activated core coolant in the chimney structure is confirmed.

Energy recovery from air flow in underground railway systems

Energy Technology Data Exchange (ETDEWEB)

Morrone, B.; Mariani, A. [Seconda Univ. degli studi di Napoli, Aversa (Italy). Dept. of Aerospace and Mechanical Engineering; Costanzo, M.L. [Tecnosistem spa, Napoli (Italy)

2010-07-01

The 20-20-20 energy policy of the European Union commits members to reduce carbon dioxide (CO{sub 2}) emissions by 20 per cent by 2020, and stipulates that 20 per cent of final-use energy is to be supplied by renewable energy sources. This paper proposed the concept of recovering energy from underground trains by using the air flow inside tunnels to drive energy conversion systems such as turbines to generate electricity. Underground trains use much of their power to overcome the aerodynamic resistance moving the air in front of the train, creating a piston effect when travelling inside tunnels at relatively low speed. Numerical simulations were used in this study to determine how much electricity could be produced. A one-dimensional numerical analysis of a specific subway train track was used to evaluate the air flow magnitude inside the tunnel. Once the air flow features were detected, the potential electricity production was evaluated by considering the characteristics of a Wells turbine. Two types of 3-dimensional models of the tunnel and train were presented. One considered a long straight tunnel with a train running in it, and a small portion of a bypass tunnel. The other considered a large part of an opposite tunnel connected to the main one through the by-pass tunnel. Both the 3D models revealed a maximum flow rate of 2.5 x 105 m{sup 3}/h, while the 1D model showed an air flow of 1.5 x 105 m{sup 3}/h. The difference was due primarily to the presence of fans in the 1D Model and different modelling assumptions. It was concluded that one single Wells type turbine placed in a by-pass tunnel can produce 32.6 kWh per day, or about 10 MWh per year, resulting in a CO{sub 2} savings of about 5.5 tons per year. 8 refs., 1 tab., 11 figs.

Off-pump coronary artery bypass surgery in selected patients is superior to the conventional approach for patients with severely depressed left ventricular function

Science.gov (United States)

Caputti, Guido Marco; Palma, José Honório; Gaia, Diego Felipe; Buffolo, Enio

2011-01-01

OBJECTIVES: Patients with coronary artery disease and left ventricular dysfunction have high mortality when kept in clinical treatment. Coronary artery bypass grafting can improve survival and the quality of life. Recently, revascularization without cardiopulmonary bypass has been presented as a viable alternative. The aim of this study is to compare patients with left ventricular ejection fractions of less than 20% who underwent coronary artery bypass graft with or without cardiopulmonary bypass. METHODS: From January 2001 to December 2005, 217 nonrandomized, consecutive, and nonselected patients with an ejection fraction less than or equal to 20% underwent coronary artery bypass graft surgery with (112) or without (off-pump) (105) the use of cardiopulmonary bypass. We studied demographic, operative, and postoperative data. RESULTS: There were no demographic differences between groups. The outcome variables showed similar graft numbers in both groups. Mortality was 12.5% in the cardiopulmonary bypass group and 3.8% in the off-pump group. Postoperative complications were statistically different (cardiopulmonary bypass versus off-pump): total length of hospital stay (days)—11.3 vs. 7.2, length of ICU stay (days)—3.7 vs. 2.1, pulmonary complications—10.7% vs. 2.8%, intubation time (hours)—22 vs. 10, postoperative bleeding (mL)—654 vs. 440, acute renal failure—8.9% vs. 1.9% and left-ventricle ejection fraction before discharge—22% vs. 29%. CONCLUSION: Coronary artery bypass grafting without cardiopulmonary bypass in selected patients with severe left ventricular dysfunction is valid and safe and promotes less mortality and morbidity compared with conventional operations. PMID:22189729

Off-pump coronary artery bypass surgery in selected patients is superior to the conventional approach for patients with severely depressed left ventricular function

Directory of Open Access Journals (Sweden)

Guido Marco Caputti

2011-01-01

Full Text Available OBJECTIVES: Patients with coronary artery disease and left ventricular dysfunction have high mortality when kept in clinical treatment. Coronary artery bypass grafting can improve survival and the quality of life. Recently, revascularization without cardiopulmonary bypass has been presented as a viable alternative. The aim of this study is to compare patients with left ventricular ejection fractions of less than 20% who underwent coronary artery bypass graft with or without cardiopulmonary bypass. METHODS: From January 2001 to December 2005, 217 nonrandomized, consecutive, and nonselected patients with an ejection fraction less than or equal to 20% underwent coronary artery bypass graft surgery with (112 or without (off-pump (105 the use of cardiopulmonary bypass. We studied demographic, operative, and postoperative data. RESULTS: There were no demographic differences between groups. The outcome variables showed similar graft numbers in both groups. Mortality was 12.5% in the cardiopulmonary bypass group and 3.8% in the off-pump group. Postoperative complications were statistically different (cardiopulmonary bypass versus off-pump: total length of hospital stay (days-11.3 vs. 7.2, length of ICU stay (days-3.7 vs. 2.1, pulmonary complications-10.7% vs. 2.8%, intubation time (hours-22 vs. 10, postoperative bleeding (mL-654 vs. 440, acute renal failure-8.9% vs. 1.9% and left-ventricle ejection fraction before discharge-22% vs. 29%. CONCLUSION: Coronary artery bypass grafting without cardiopulmonary bypass in selected patients with severe left ventricular dysfunction is valid and safe and promotes less mortality and morbidity compared with conventional operations.

Phase change based cooling for high burst mode heat loads with temperature regulation above the phase change temperature

Science.gov (United States)

The United States of America as represented by the United States Department of Energy

2009-12-15

An apparatus and method for transferring thermal energy from a heat load is disclosed. In particular, use of a phase change material and specific flow designs enables cooling with temperature regulation well above the fusion temperature of the phase change material for medium and high heat loads from devices operated intermittently (in burst mode). Exemplary heat loads include burst mode lasers and laser diodes, flight avionics, and high power space instruments. Thermal energy is transferred from the heat load to liquid phase change material from a phase change material reservoir. The liquid phase change material is split into two flows. Thermal energy is transferred from the first flow via a phase change material heat sink. The second flow bypasses the phase change material heat sink and joins with liquid phase change material exiting from the phase change material heat sink. The combined liquid phase change material is returned to the liquid phase change material reservoir. The ratio of bypass flow to flow into the phase change material heat sink can be varied to adjust the temperature of the liquid phase change material returned to the liquid phase change material reservoir. Varying the flowrate and temperature of the liquid phase change material presented to the heat load determines the magnitude of thermal energy transferred from the heat load.

Hematological Disorders following Gastric Bypass Surgery: Emerging Concepts of the Interplay between Nutritional Deficiency and Inflammation

Directory of Open Access Journals (Sweden)

Mingyi Chen

2013-01-01

Full Text Available Obesity and the associated metabolic syndrome are among the most common and detrimental metabolic diseases of the modern era, affecting over 50% of the adult population in the United States. Surgeries designed to promote weight loss, known as bariatric surgery, typically involve a gastric bypass procedure and have shown high success rates for treating morbid obesity. However, following gastric bypass surgery, many patients develop chronic anemia, most commonly due to iron deficiency. Deficiencies of vitamins B1, B12, folate, A, K, D, and E and copper have also been reported after surgery. Copper deficiency can cause hematological abnormalities with or without neurological complications. Despite oral supplementation and normal serum concentrations of iron, copper, folate, and vitamin B12, some patients present with persistent anemia after surgery. The evaluation of hematologic disorders after gastric bypass surgery must take into account issues unique to the postsurgery setting that influence the development of anemia and other cytopenias. In this paper, the clinical characteristics and differential diagnosis of the hematological disorders associated with gastric bypass surgery are reviewed, and the underlying molecular mechanisms are discussed.

Linear and nonlinear stability of a thermally stratified magnetically driven rotating flow in a cylinder.

Science.gov (United States)

Grants, Ilmars; Gerbeth, Gunter

2010-07-01

The stability of a thermally stratified liquid metal flow is considered numerically. The flow is driven by a rotating magnetic field in a cylinder heated from above and cooled from below. The stable thermal stratification turns out to destabilize the flow. This is explained by the fact that a stable stratification suppresses the secondary meridional flow, thus indirectly enhancing the primary rotation. The instability in the form of Taylor-Görtler rolls is consequently promoted. These rolls can only be excited by finite disturbances in the isothermal flow. A sufficiently strong thermal stratification transforms this nonlinear bypass instability into a linear one reducing, thus, the critical value of the magnetic driving force. A weaker temperature gradient delays the linear instability but makes the bypass transition more likely. We quantify the non-normal and nonlinear components of this transition by direct numerical simulation of the flow response to noise. It is observed that the flow sensitivity to finite disturbances increases considerably under the action of a stable thermal stratification. The capabilities of the random forcing approach to identify disconnected coherent states in a general case are discussed.

Extra-Thoracic Supra-aortic Bypass Surgery Is Safe in Thoracic Endovascular Aortic Repair and Arterial Occlusive Disease Treatment.

Science.gov (United States)

Gombert, Alexander; van Issum, Lea; Barbati, Mohammad E; Grommes, Jochen; Keszei, Andras; Kotelis, Drosos; Jalaie, Houman; Greiner, Andreas; Jacobs, Michael J; Kalder, Johannes

2018-04-20

The safety and feasibility of supra-aortic debranching as part of endovascular aortic surgery or as a treatment option for arterial occlusive disease (AOD) remains controversial. The aim of this study was to assess the clinical outcome of this surgery. This single centre, retrospective study included 107 patients (mean age 69.2 years, 38.4% women) who underwent supra-aortic bypass surgery (carotid-subclavian bypass, carotid-carotid bypass, and carotid-carotid-subclavian bypass) because of thoracic or thoraco-abdominal endovascular aortic repair (57%; 61/107) or as AOD treatment (42.9%; 46/107) between January 2006 and January 2015. Mortality, morbidity with a focus on neurological complications, and patency rate were assessed. Twenty-six of 107 (14.2%) of the debranching patients were treated under emergency conditions because of acute type B dissection or symptomatic aneurysm. Follow up, conducted by imaging interpretation and telephone interviews, continued till March 2017 (mean 42.1, 0-125, months). The in hospital mortality rate was 10.2% (11/107), all of these cases from the debranching group and related to emergency procedures (p supra-aortic bypass surgery involves low complication rates and high mid-term bypass patency rates. It is a safe and feasible treatment option in the form of debranching in combination with endovascular aortic aneurysm repair and in AOD. Copyright © 2018 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.

Computational and experimental studies of the flow field near the beam entrance window of a liquid metal target

International Nuclear Information System (INIS)

Geža, Vadims; Milenković, Rade Ž.; Kapulla, Ralf; Dementjevs, Sergejs; Jakovičs, Andris; Wohlmuther, Michael

2014-01-01

Highlights: • Water model of liquid metal target for validation of CFD models was built. • PIV measurements showed flow features in the region near beam entrance window. • The zones with high turbulence kinetic energy were distinguished. • Reasonable agreement between modeling and PIV data was obtained. - Abstract: After the first world liquid metal target has been successfully operated at the SINQ facility at the Paul Scherrer Institut (PSI) for 6 months. The idea of having a reliable target with a bypass flow for cooling the beam entrance window, but with the bypass flow not driven by a separate pump, was examined within the project called LIMETS (Liquid Metal Target for SINQ). In designing of liquid metal targets, turbulence modelling is of high importance due to lack in methods for measuring the spatial distribution of flow and turbulence characteristics. In this study, validation of different turbulence models were performed in water model with hemispherical geometry using particle image velocimetry (PIV) technique. Two components of water flow velocity in plexiglas container with inner radius of 88 mm were measured in different cross sections, with the velocities varying from 1 to 10 m/s. Numerical calculations using large eddy simulation (LES) approach and Reynolds averaged Navier–Stokes (RANS) models were carried out to validate their applicability and study performance issues. Mean velocity and turbulence kinetic energy data were used for comparison of PIV and calculation results. Reasonable agreement was obtained for mean velocity data, with some discrepancies due to the limited length of the inlet tube. However, several discrepancies in turbulence characteristics were found in numerical results, especially in RANS model calculations

Free-Surface flow dynamics and its effect on travel time distribution in unsaturated fractured zones - findings from analogue percolation experiments

Science.gov (United States)

Noffz, Torsten; Kordilla, Jannes; Dentz, Marco; Sauter, Martin

2017-04-01

Flow in unsaturated fracture networks constitutes a high potential for rapid mass transport and can therefore possibly contributes to the vulnerability of aquifer systems. Numerical models are generally used to predict flow and transport and have to reproduce various complex effects of gravity-driven flow dynamics. However, many classical volume-effective modelling approaches often do not grasp the non-linear free surface flow dynamics and partitioning behaviour at fracture intersections in unsaturated fracture networks. Better process understanding can be obtained by laboratory experiments, that isolate single aspects of the mass partitioning process, which influence travel time distributions and allow possible cross-scale applications. We present a series of percolation experiments investigating partitioning dynamics of unsaturated multiphase flow at an individual horizontal fracture intersection. A high precision multichannel dispenser is used to establish gravity-driven free surface flow on a smooth and vertical PMMA (poly(methyl methacrylate)) surface at rates ranging from 1.5 to 4.5 mL/min to obtain various flow modes (droplets; rivulets). Cubes with dimensions 20 x 20 x 20 cm are used to create a set of simple geometries. A digital balance provides continuous real-time cumulative mass bypassing the network. The influence of variable flow rate, atmospheric pressure and temperature on the stability of flow modes is shown in single-inlet experiments. Droplet and rivulet flow are delineated and a transition zone exhibiting mixed flow modes can be determined. Furthermore, multi-inlet setups with constant total inflow rates are used to reduce variance and the effect of erratic free-surface flow dynamics. Investigated parameters include: variable aperture widths df, horizontal offsets dv of the vertical fracture surface and alternating injection methods for both droplet and rivulet flow. Repetitive structures with several horizontal fractures extend arrival times

Nutrient deficiency and obstetrical outcomes in pregnant women following Roux-en-Y gastric bypass

DEFF Research Database (Denmark)

Hammeken, Lianna Hede; Betsagoo, Ramsina; Jensen, Ann Nygaard

2017-01-01

OBJECTIVE: Roux-en-Y gastric bypass surgery and small-for-gestational-age births are known to be associated although the etiology is not fully understood. This study aimed to investigate pregnancy outcomes and maternal nutritional status among pregnant women with a history of Roux-en-Y gastric...... obstetric clinic at Aalborg University Hospital in Denmark and gave birth between 1 January 2010 and 31 December 2013 were included. Each Roux-en-Y-gastric-bypass-operated woman was closely matched with a non-Roux-en-Y-gastric-bypass-operated woman. Primary outcomes were small-for-gestational-age birth.......169) between women with a history of Roux-en-Y gastric bypass (11.51kg±8.97 standard deviation (SD)) and non- Roux-en-Y-gastric-bypass-operated women (12.18kg±6.28 SD). CONCLUSION: A history of Roux-en-Y gastric bypass surgery increases the risk of small-for-gestational-age birth and anemia, while a finding...

Standardizing instream flow requirements at hydropower projects in the Cascade Mountains, Washington

Energy Technology Data Exchange (ETDEWEB)

Smith, I.M.; Sale, M.J.

1993-06-01

Instream flow requirements are common mitigation measures instituted in the bypassed reaches of hydroelectric diversion projects. Currently, there are two extremes among the ways to determine instream flow requirements: generic standard-setting methods and detailed, habitat-based, impact assessment methods such as the Instream Flow Incremental Methodology (IFIM). Data from streams in Washington state show a consistent pattern in the instream flow requirements resulting from the IFIM. This pattern can be used to refine the simpler standard-setting approaches and thereby provide better estimates of flow needs during early stages of project design.

Simulation of blood flow in a small-diameter vascular graft model with a swirl (spiral) flow guider.

Science.gov (United States)

Zhang, ZhiGuo; Fan, YuBo; Deng, XiaoYan; Wang, GuiXue; Zhang, He; Guidoin, Robert

2008-10-01

Small-diameter vascular grafts are in large demand for coronary and peripheral bypass procedures, but present products still fail in long-term clinical application. In the present communication, a new type of small-diameter graft with a swirl flow guider was proposed to improve graft patency rate. Flow pattern in the graft was simulated numerically and compared with that in a conventional graft. The numerical results revealed that the swirl flow guider could indeed make the blood flow rotate in the new graft. The swirling flow distal to the flow guider significantly altered the flow pattern in the new graft and the velocity profiles were re-distributed. Due to the swirling flow, the blood velocity near the vessel wall and wall shear rate were greatly enhanced. We believe that the increased blood velocity near the wall and the wall shear rate can impede the occurrence of acute thrombus formation and intimal hyperplasia, hence can improve the graft patency rate for long-term clinical use.

Grain Flow at High Stresses

Science.gov (United States)

McSaveney, M. J.

2015-12-01

The transport mechanism of rapid long-runout rock avalanches was a hotly debated topic when I came on the scene in 1967. So how come it is still debated today? My explanation is that it is the expected outcome of peer review, poor comprehension, and technological advances outpacing intellectual advances. Why think about the problem when we can model it! So let us think about the problem. Shreve thought that rock avalanches fell upon and trapped a layer of air. What physics was he thinking about? It is how feathers and tissue papers fall. When my rock avalanches fly, they fly like unlubricated bricks using the physics of projectiles and ballistics. But the main transport mechanism is not flight. The dominant impression from watching a rock avalanche in motion is of fluid flow, as Heim described it in 1882. A rock avalanche is a very large grain flow. Bagnold studied dispersive grain flows, but why should one assume that rock avalanches are dispersive grain flows as many do. The more common grain flow type is a dense grain flow and rock avalanches are dense grain flows in which the weight can and does generate very high stresses at grain contacts. Brittle rock deforms elastically up to its compressive strength, whereupon it breaks, releasing elastic strain as transient elastic strain (seismic energy to a seismologist, acoustic energy to a physicist). Melosh and others have shown that acoustic energy can fluidize a grain mass. There is no exotic physics behind grain flow at high stress. When grains break, the released elastic strain has to go somewhere, and it goes somewhere principally by transmission though grain contacts. Depending on the state of stress at the grain contact, the contact will pass the stress or will slip at conventional values of Coulomb friction. Enough thinking! A physical model of the entire process is too big for any laboratory. So whose numerical model will do it?

Sodium/hydrogen-exchanger inhibition during cardioplegic arrest and cardiopulmonary bypass: an experimental study.

Science.gov (United States)

Cox, Charles S; Sauer, Henning; Allen, Steven J; Buja, L Maximilian; Laine, Glen A

2002-05-01

We sought to determine whether pretreatment with a sodium/hydrogen-exchange inhibitor (EMD 96 785) improves myocardial performance and reduces myocardial edema after cardioplegic arrest and cardiopulmonary bypass. Anesthetized dogs (n = 13) were instrumented with vascular catheters, myocardial ultrasonic crystals, and left ventricular micromanometers to measure preload recruitable stroke work, maximum rate of pressure rise (positive and negative), and left ventricular end-diastolic volume and pressure. Cardiac output was measured by means of thermodilution. Myocardial tissue water content was determined from sequential biopsy. After baseline measurements, hypothermic (28 degrees C) cardiopulmonary bypass was initiated. Cardioplegic arrest (4 degrees C Bretschneider crystalloid cardioplegic solution) was maintained for 2 hours, followed by reperfusion-rewarming and separation from cardiopulmonary bypass. Preload recruitable stroke work and myocardial tissue water content were measured at 30, 60, and 120 minutes after bypass. EMD 96 785 (3 mg/kg) was given 15 minutes before bypass, and 2 micromol was given in the cardioplegic solution. Control animals received the same volume of saline vehicle. Arterial-coronary sinus lactate difference was similar in both animals receiving EMD 96 785 and control animals, suggesting equivalent myocardial ischemia in each group. Myocardial tissue water content increased from baseline in both animals receiving EMD 96 785 and control animals with cardiopulmonary bypass and cardioplegic arrest but was statistically lower in animals receiving EMD 96 785 compared with control animals (range, 1.0%-1.5% lower in animals receiving EMD 96 785). Preload recruitable stroke work decreased from baseline (97 +/- 2 mm Hg) at 30 (59 +/- 6 mm Hg) and 60 (72 +/- 9 mm Hg) minutes after cardiopulmonary bypass and cardioplegic arrest in control animals; preload recruitable stroke work did not decrease from baseline (98 +/- 2 mm Hg) in animals receiving

21 CFR 870.4210 - Cardiopulmonary bypass vascular catheter, cannula, or tubing.

Science.gov (United States)

2010-04-01

..., or tubing. 870.4210 Section 870.4210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 870.4210 Cardiopulmonary bypass vascular catheter, cannula, or tubing. (a) Identification. A cardiopulmonary bypass vascular catheter, cannula, or tubing is a device used in cardiopulmonary surgery to...

Investigations on high speed MHD liquid flow

International Nuclear Information System (INIS)

Yamasaki, Takasuke; Kamiyama, Shin-ichi.

1982-01-01

Lately, the pressure drop problem of MHD two-phase flow in a duct has been investigated theoretically and experimentally in conjunction with the problems of liquid metal MHD two-phase flow power-generating cycle or of liquid metal boiling two-phase flow in the blanket of a nuclear fusion reactor. Though many research results have been reported so far for MHD single-phase flow, the hydrodynamic studies on high speed two-phase flow are reported only rarely, specifically the study dealing with the generation of cavitation is not found. In the present investigation, the basic equation was derived, analyzing the high speed MHD liquid flow in a diverging duct as the one-dimensional flow of homogeneous two-phase fluid of small void ratio. Furthermore, the theoretical solution for the effect of magnetic field on cavitation-generating conditions was tried. The pressure distribution in MHD flow in a duct largely varies with load factor, and even if the void ratio is small, the pressure distribution in two-phase flow is considerably different from that in single-phase flow. Even if the MHD two-phase flow in a duct is subsonic flow at the throat, the critical conditions may be achieved sometimes in a diverging duct. It was shown that cavitation is more likely to occur as magnetic field becomes more intense if it is generated downstream of the throat. This explains the experimental results qualitatively. (Wakatsuki, Y.)

Rural Bypass of Critical Access Hospitals in Iowa: Do Visiting Surgical Specialists Make a Difference?

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Weigel, Paula A M; Ullrich, Fred; Ward, Marcia M

2018-02-01

Rural bypass for elective surgical procedures is a challenge for critical access hospitals, yet there are opportunities for rural hospitals to improve local retention of surgical candidates through alternative approaches to developing surgery lines of business. In this study we examine the effect of visiting surgical specialists on the odds of rural bypass. Discharge data from the 2011 State Inpatient Databases and State Ambulatory Surgery Databases for Iowa were linked to outreach data from the Office of Statewide Clinical Education Programs and Iowa Physician Information System to model the effect of surgeon specialist supply on rural patients' decision to bypass rural critical access hospitals. Patients in rural communities with a local general surgeon were more likely to be retained in a community than to bypass. Those in communities with visiting general surgeons were more likely to bypass, as were those in communities with visiting urologists and obstetricians. Patients in communities with visiting ophthalmologists and orthopedic surgeons were at higher odds of being retained for their elective surgeries. In addition to known patient and local hospital factors that have an influence on bypass behavior among rural patients seeking elective surgery, availability of surgeon specialists also plays an important role in whether patients bypass or not. Visiting ophthalmologists and orthopedic surgeons were associated with less bypass, as was having local general surgeons. Visiting general surgeons, urologists, and obstetricians were associated with greater odds of bypass. © 2016 National Rural Health Association.

Impairment of neuropsychological function in patients with hemodynamic cerebral ischemia and efficacy of bypass surgery

Energy Technology Data Exchange (ETDEWEB)

Sasoh, Masayuki [Iwate Medical Univ., Morioka (Japan). School of Medicine

1999-08-01

In order to evaluate the relation between neuropsychological functions and hemodynamic cerebral ischemia, the author analyzed neuropsychological examination and the cerebral blood flow and metabolism of patients before and after bypass surgery. Twenty-five patients were defined by clinical and laboratory criteria as suffering from hemodynamic cerebral ischemia. All patients had one or more episodes of focal cerebral ischemia due to unilateral internal carotid or middle cerebral artery occlusion. Computerized tomography scans either were normal or showed evidence of watershed infarction. Based on these criteria, superficial temporal artery-proximal middle cerebral artery anastomosis was performed. The baseline cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate of oxygen (CMRO{sub 2}) and cerebrovascular reserve capacity (CVRC) were studied using positron emission computerized tomography (PET) and the acetazolamide test. Neuropsychological evaluations including Hasegawa Dementia Scale-Revised, Mini-Mental State and Wechsler Adult Intelligence Scale-Revised (WAIS-R), and PET study were completed one month after the last ischemic event and 3-6 months after the operation. A significant negative correlation was observed between OEF and neuropsychological functions. Postoperative neuropsychological functions showed significant improvement. Significant correlations were observed for {delta}WAIS-R (preoperative WAIS-R postoperative WAIS-R) versus preoperative CMRO{sub 2} (r=0.52), for {delta}WAIS-R versus preoperative OEF (r=0.47). In view of these findings, the author concludes that elevation of OEF impairs neuropsychological functions and bypass surgery improves neuropsychological functions in patients with normal CMRO{sub 2} and elevated OEF. (author)

Arterial pressure during cardiopulmonary bypass is not associated with acute kidney injury

DEFF Research Database (Denmark)

Kandler, K; Jensen, M E; Nilsson, J C

2015-01-01

BACKGROUND: Acute kidney injury (AKI) after cardiac surgery is common and is associated with increased mortality. We wanted to investigate if the arterial pressure or the use of norepinephrine during cardiopulmonary bypass were associated with AKI. METHODS: A retrospective analysis of patients who...... underwent coronary artery bypass grafting with or without concomitant procedures was conducted. AKI was defined using the RIFLE criteria. Data on arterial pressure and use of norepinephrine during cardiopulmonary bypass were entered in a binary logistic regression model to control for possible perioperative...... and in higher amounts, during cardiopulmonary bypass, in patients who developed AKI. These differences in arterial pressures and use of norepinephrine between the groups were not found to be significant when entered in the binary logistic regression model. CONCLUSION: No independent relationship between...

Double bypass for inoperable pancreatic malignancy at laparotomy: postoperative complications and long-term outcome

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Ausania, F; Vallance, AE; Manas, DM; Prentis, JM; Snowden, CP; White, SA; Charnley, RM; French, JJ; Jaques, BC

2012-01-01

INTRODUCTION Between 4% and 13% of patients with operable pancreatic malignancy are found unresectable at the time of surgery. Double bypass is a good option for fit patients but it is associated with high risk of postoperative complications. The aim of this study was to identify pre-operatively which patients undergoing double bypass are at high risk of complications and to assess their long-term outcome. METHODS Of the 576 patients undergoing pancreatic resections between 2006 and 2011, 50 patients who underwent a laparotomy for a planned pancreaticoduodenectomy had a double bypass procedure for inoperable disease. Demographic data, risk factors for postoperative complications and pre-operative anaesthetic assessment data including the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM) and cardiopulmonary exercise testing (CPET) were collected. RESULTS Fifty patients (33 men and 17 women) were included in the study. The median patient age was 64 years (range: 39–79 years). The complication rate was 50% and the in-hospital mortality rate was 4%. The P-POSSUM physiology subscore and low anaerobic threshold at CPET were significantly associated with postoperative complications (p=0.005 and p=0.016 respectively) but they were unable to predict them. Overall long-term survival was significantly shorter in patients with postoperative complications (9 vs 18 months). Postoperative complications were independently associated with poorer long-term survival (p=0.003, odds ratio: 3.261). CONCLUSIONS P-POSSUM and CPET are associated with postoperative complications but the possibility of using them for risk prediction requires further research. However, postoperative complications following double bypass have a significant impact on long-term survival and this type of surgery should therefore only be performed in specialised centres. PMID:23131226

Analysis of the Vortex Street Generated at the Core-Bypass Lip of a Jet-Engine Nozzle

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Nogueira, José; Legrand, Mathieu; Nauri, Sara; Rodríguez, Pedro A.; Lecuona, Antonio

The reduction of the noise generated by jet-engine aircrafts is of growing concern in the present society. A better understanding of the aircraft noise production and the development of predictive tools is of great interest. Within this framework, the CoJeN (Coaxial Jet Noise) European Project includes the measurement of the flow field and the noise generated by typical turbofan jet-engine nozzles. One of the many aspects of interest is the occasional presence of acoustic tones of a defined frequency, symptomatic of the presence of quasiperiodic coherent structures within the flow. This chapter analyzes the characteristics of a vortex street in the core-bypass lip of one of the nozzles under study. The measurements were made by means of advanced PIV techniques within the above-mentioned project.

21 CFR 870.4270 - Cardiopulmonary bypass cardiotomy suction line blood filter.

Science.gov (United States)

2010-04-01

... blood filter. 870.4270 Section 870.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Devices § 870.4270 Cardiopulmonary bypass cardiotomy suction line blood filter. (a) Identification. A cardiopulmonary bypass cardiotomy suction line blood filter is a device used as part of a gas exchange (oxygenator...

Conversion of Low-Flow Priapism to High-Flow State Using T-Shunt with Tunneling.

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Mistry, Neil A; Tadros, Nicholas N; Hedges, Jason C

2017-01-01

Introduction . The three types of priapism are stuttering, arterial (high-flow, nonischemic), and venoocclusive (low-flow, ischemic). These are usually distinct entities and rarely occur in the same patient. T-shunts and other distal shunts are frequently combined with tunneling, but a seldom recognized potential complication is conversion to a high-flow state. Case Presentation . We describe 2 cases of men who presented with low-flow priapism episodes that were treated using T-shunts with tunneling that resulted with both men having recurrent erections shortly after surgery that were found to be consistent with high-flow states. Case 1 was a 33-year-old male with sickle cell anemia and case 2 was a 24-year-old male with idiopathic thrombocytopenic purpura. In both cases the men were observed over several weeks and both men returned to normal erectile function. Conclusions . Historically, proximal shunts were performed only in cases when distal shunts failed and carry a higher risk of serious complications. T-shunts and other distal shunts combined with tunneling are being used more frequently in place of proximal shunts. These cases illustrate how postoperative erections after T-shunts with tunneling can signify a conversion from low-flow to high-flow states and could potentially be misdiagnosed as an operative failure.

Pre-operative anxiety in patients undergoing coronary artery bypass graft surgery – A cross-sectional study

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C. Ramesh

Full Text Available Background: Coronary artery bypass graft surgery is an important treatment for the patients with coronary artery disease to reduce angina and enhance the quality of life. Anxiety is a usual reaction to a stressful situation and is existing in patients awaiting surgery. Objective: The objective of the study was to assess pre-operative anxiety in patients who were undergoing coronary artery bypass graft surgery. Methods: A cross-sectional study consisting of 140 patients undergoing coronary artery bypass graft surgery were included in the study using a convenience sampling technique in a tertiary care referral hospital. The data was collected using state-trait anxiety inventory. The data were entered into SPSS (version – 20.0 for windows and descriptive and inferential statistics were performed. Results: The study enrolled 140 (117 males and 23 females patients. Their mean age was 57.29 ± 8.14 (range 35–70 years. Most of the patients 118 (84% had preoperative anxiety before coronary artery bypass graft surgery. There was an association found between gender and anxiety with Pearson chi-square value of 11.57 (p < 0.001. Discussion: Patients undergoing coronary artery bypass graft surgery is experiencing the high level of pre-operative anxiety and females had higher anxiety than the males. Identification of the pre-operative anxiety in patients undergoing CABG surgery is essential because it helps the health professionals and nurses to develop effective and appropriate interventions. Keywords: Preoperative period, Anxiety, Coronary artery bypass, Perioperative care

Urgent Bypass Surgery Following Failed Endovascular Treatment in Acute Symptomatic Stroke Patient With MCA Occlusion.

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Lee, Chang Yeob; Kim, Chang Hyun; Lee, Chang-Young; Sohn, Sung-Il; Hong, Jeong-Ho

2017-01-01

Although the benefits of extracranial-intracranial bypass surgery remain controversial, there is some surgical rationale for the augmentation of cerebral blood flow in cases of acute ischemic stroke with hemodynamic instability. We report a case of a 62-year-old woman who suddenly developed right hemiplegia and global aphasia. Initial magnetic resonance imaging and magnetic resonance angiography revealed a small acute ischemic lesion in left parietal lobe with occlusion at the left middle cerebral artery. We performed an endovascular thrombectomy, which failed. Her neurological deficits remained unchanged. On the basis of immediate postendovascular magnetic resonance perfusion, diffusion-weighted imaging (DWI), and neurological examination, an obvious clinical-DWI and a DWI-perfusion-weighted imaging mismatch were detected. We decided to perform emergency superficial temporal artery to middle cerebral artery bypass to prevent further progression of cerebral ischemia. On a 3-month follow-up, neurological deficits remained minimal motor aphasia and dysarthria. Following failed endovascular treatment in patients with acute symptoms attributed to major cerebral artery occlusion, we recommend immediate multimodal neuroimaging. If there are clinical-DWI and DWI-perfusion-weighted imaging mismatch indications, surgical revascularization could be considered as the next salvageable strategy.

Development and evaluation of totally implantable ventricular assist system using a vibrating flow pump and transcutaneous energy transmission system with amorphous fibers.

Science.gov (United States)

Yambe, T; Hashimoto, H; Kobayashi, S; Sonobe, T; Naganuma, S; Nanka, S S; Matsuki, H; Yoshizawa, M; Tabayashi, K; Takayasu, H; Takeda, H; Nitta, S

1997-01-01

We have developed a vibrating flow pump (VFP) that can generate oscillated blood flow with a relatively high frequency (10-50 Hz) for a totally implantable ventricular assist system (VAS). To evaluate the newly developed VAS, left heart bypasses, using the VFP, were performed in chronic animal experiments. Hemodynamic parameters were recorded in a data recorder in healthy adult goats during an awake condition and analyzed in a personal computer system through an alternating-direct current converter. Basic performance of the total system with a transcutaneous energy transmission system were satisfactory. During left ventricular assistance with the VFP, Mayer wave fluctuations of hemodynamics were decreased in the power spectrum, the fractal dimensions of the hemodynamics were significantly decreased, and peripheral vascular resistance was significantly decreased. These results suggest that cardiovascular regulatory nonlinear dynamics, which mediate the hemodynamics, may be affected by left ventricular bypass with oscillated flow. The decreased power of the Mayer wave in the spectrum caused the limit cycle attractor of the hemodynamics and decreased peripheral resistance. These results suggest that this newly developed VAS is useful for the totally implantable system with unique characteristics that can control hemodynamic properties.

78. Coronary bypass using bilateral internal mammary arteries in an achondroplast

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Mohamed Abdulwahab Alassal

2015-10-01

Full Text Available Coronary bypass grafting for ischemic heart disease in achondroplastic dwarfs is very rare. Shortage of veins and sometimes, inadequate vein quality can cause difficulties during surgery. Only two achondroplastic cases were reported in literature that underwent coronary bypass surgery, in which the left internal mammary artery and vein grafts were used. To the best of our knowledge using bilateral internal mammary arteries in such patients was not reported. We report here a 55 years old male achondroplastic dwarf who had triple vessels coronary disease that underwent successful coronary bypass surgery using bilateral mammary arteries. Anatomic and surgical challenges in achondroplasia are highlighted

Assessment of extracranial-intracranial bypass patency with 64-slice multidetector computerized tomography angiography

Energy Technology Data Exchange (ETDEWEB)

Thines, Laurent [Lille University Hospital, Department of Neurosurgery, Lille (France); Toronto Western Hospital, Division of Neurosurgery and Department of Surgery, Toronto, ON (Canada); Toronto Western Hospital, University of Toronto Brain Vascular Malformation Study Group, Toronto, ON (Canada); Agid, Ronit; Da Costa, Leodante; Terbrugge, Karel G. [Toronto Western Hospital, Division of Neuroradiology, Department of Medical Imaging, Toronto, ON (Canada); Toronto Western Hospital, University of Toronto Brain Vascular Malformation Study Group, Toronto, ON (Canada); Dehdashti, Amir R.; Wallace, M.C.; Tymianski, Michael [Toronto Western Hospital, Division of Neurosurgery and Department of Surgery, Toronto, ON (Canada); Toronto Western Hospital, University of Toronto Brain Vascular Malformation Study Group, Toronto, ON (Canada)

2009-08-15

Extracranial-intracranial (EC/IC) bypass is a useful procedure for the treatment of cerebral vascular insufficiency or complex aneurysms. We explored the role of multidetector computed tomography angiography (MDCTA), instead of digital subtraction angiography (DSA), for the postoperative assessment of EC/IC bypass patency. We retrospectively analyzed a consecutive series of 21 MDCTAs from 17 patients that underwent 25 direct or indirect EC/IC bypass procedures between April 2003 and November 2007. Conventional DSA was available for comparison in 13 cases. MDCTA used a 64-slice MDCT scanner (Aquilion 64, Toshiba). The proximal and distal patencies were analyzed independently on MDCTA and DSA by a neuroradiologist and a neurosurgeon. The bypass was considered patent when the entire donor vessel was opacified without discontinuity from proximal to distal ends and was visibly in contact with the recipient vessel. MDCTA depicted the patency status in every patient. Bypasses were patent in 22 cases, stenosed in one, and occluded in two. DSA always confirmed the results of the MDCTA (sensitivity = 100%, 95% CI = 0.655-1.0; specificity 100%, 95% CI = 0.05-1.0). MDCTA is a non-invasive and accurate exam to assess the postoperative EC/IC bypass patency and is a promising technique in routine follow-up. (orig.)

Oxygen delivery and consumption during on-bypass cabg in htea and central analgesia

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Віталій Олексійович Собокарь

2015-04-01

Full Text Available Objective. Despite some advantages, the use of high thoracic epidural anesthesia (HTEA during on-bypass cardiac surgery may be discouraged by fear of adverse hemodynamic effects and associated disturbances of oxygen delivery.Aim. To compare oxygen delivery and consumption during on-bypass coronary artery bypass grafting in settings of HTEA and central analgesia (CA.Methods. 132 patients were assigned into two groups – study group (n=85, where the surgery was performed under HTEA and control group (n=47 - where the surgery was carried out under CA. Using data of transesophageal cardiac ultrasound and blood oximetry blood oxygen delivery (DO2, oxygen consumption (VO2, oxygen extraction coefficient (CEO2 were calculated at four stages of the surgery: after induction, sternotomy, cardiopulmonary bypass and at the end of the surgery.Results. In the initial stages of the surgery DO2 and VO2 were reduced relative to reference values with a tendency to increase in the course of the operation and achievement of the normal or supernormal level (VO2, study group in the final stage. The decrease was due to moderate hypodynamic circulation and hemodilution. After sternotomy DO2 in the study group was higher than that of the control: 356 (279; 458 vs 317±89 ml·min-1·m-2, (р=0,021. After cardiopulmonary bypass oxygen saturation of venous blood (SatvO2, in the study group was 71 ± 9 % compared with 68 ± 10 % in the control group. At the end of the surgery SatvO2 in the study group was 71 (66; 75 vs 59 (53; 70 % in the control (р = 0,005 and oxygen tension of venous blood (РvО2 was correspondingly 39 ± 6 and 33 (30; 38 mm Hg (р = 0,027. Despite the decrease in DO2 and VO2, oxygen extraction indices - CEO2, pvO2, SatvO2, and remained within the reference range, except that of the control group at the end of the surgery. Furthermore, at no stage lactate rise or acid-base deviations was observed in the both groups.Conclusions. In patients operated

Influence of cardiopulmonary bypass on the interaction of recombinant factor VIIa with activated platelets

DEFF Research Database (Denmark)

Kjalke, M.; Runge, M.; Rojkjaer, R.

2009-01-01

Recombinant factor VIIa (rFVIIa) interacts preferentially with coated platelets characterized by a high exposure of phosphatidyl serine (PS), FV, FVIII, FIX, and FX binding, and fibrinogen. Cardiopulmonary bypass (CPB) is known to impair platelet function. In this study, the influence of CPB...

[TRANSPORT OF OXYGEN DURING GEOMETRICAL RECONSTRUCTION OF THE LEFT VENTRICLE IN CONJUNCTION WITH CORONARY ARTERY BYPASS GRAFTING AND USING OF HIGH THORACIC EPIDURAL ANESTHESIA AS A MAJOR COMPONENT OF GENERAL ANAESTHESIA].

Science.gov (United States)

Zatevahina, M V; Farzutdinov, A F; Rahimov, A A; Makrushin, I M; Kvachantiradze, G Y

2015-01-01

The purpose of the study is to examine the perioperative dynamics of strategic blood oxygen transport indicators: delivery (DO2), consumption (VO2), the coefficient of oxygen uptake (CUO2) and their composition, as well as the dynamics of blood lactate indicators in patients with ischaemic heart disease (IHD) who underwent surgery under cardiopulmonary bypass with high thoracic epidural anaesthesia (HTEA) as the main component of anesthesia. Research was conducted in 30 patients with a critical degree of operational risk, during the correction of post-infarction heart aneurysmn using the V. Dor method in combination with coronary artery bypass grafting. The strategic blood oxygen transport indicators (delivery, consumption and the oxygen uptake coefficient) showed a statistically significant decrease compared to the physiological norm and to the initial data at two points of the research: the intubation of the trachea and during cardiopulmonary bypass. The system components of oxygen were influenced at problematic stages by the dynamics of SvO2 (increase), AVD (decrease), hemodilution withe fall of the HIb- in the process of JR in the persence of superficial hypothermia. The maintenance of optimal CA in the context of HTEA, combined with a balanced volemic load and a minimized cardiotonic support ensured the stabilisation of strategic blood oxygen transport indicators aithe postperfusion stage and during the immediate postoperative period The article is dedicated to the study of strategic blood oxygen transport indicators and their components during the operation of geometric reconstruc-tion of the left ventricle combined with coronary artery-bypass using cardiopulmonary bypass and with high thoracic epidural anesthesia as the main component of general anaesthesia. The analysis has covered the stagewise delivery dynamics, consumption and the oxygen uptake coefficient at II stages of the operation and of the immediate postoperative period. The study has ident (fled

Management of Post-Traumatic Phlegmasia Cerulea Dolens via Right-to-Left Femoral Vein to Femoral Vein Bypass (Palma Procedure).

Science.gov (United States)

Dua, Anahita; Heller, Jennifer; Lee, Cheong

2017-11-01

Phlegmasia cerulea dolens (PCD) is a rare condition resulting from venous occlusion that impairs arterial flow. We report a rare case of post-traumatic PCD after ligation of the iliac vein with successful treatment by right-to-left femoral vein to femoral vein bypass using left great saphenous vein (Palma procedure). The clinical presentation, diagnostic process, and approach to management along with a literature review on the operative management of PCD are presented in this case report.

Fluidic actuators for active flow control on airframe

Science.gov (United States)

Schueller, M.; Weigel, P.; Lipowski, M.; Meyer, M.; Schlösser, P.; Bauer, M.

2016-04-01

One objective of the European Projects AFLoNext and Clean Sky 2 is to apply Active Flow Control (AFC) on the airframe in critical aerodynamic areas such as the engine/wing junction or the outer wing region for being able to locally improve the aerodynamics in certain flight conditions. At the engine/wing junction, AFC is applied to alleviate or even eliminate flow separation at low speeds and high angle of attacks likely to be associated with the integration of underwing- mounted Ultra High Bypass Ratio (UHBR) engines and the necessary slat-cut-outs. At the outer wing region, AFC can be used to allow more aggressive future wing designs with improved performance. A relevant part of the work on AFC concepts for airframe application is the development of suitable actuators. Fluidic Actuated Flow Control (FAFC) has been introduced as a Flow Control Technology that influences the boundary layer by actively blowing air through slots or holes out of the aircraft skin. FAFC actuators can be classified by their Net Mass Flux and accordingly divided into ZNMF (Zero Net Mass Flux) and NZNMF (Non Zero Net-Mass-Flux) actuators. In the frame of both projects, both types of the FAFC actuator concepts are addressed. In this paper, the objectives of AFC on the airframe is presented and the actuators that are used within the project are discussed.

Use of 123I-IMP brain SPET to predict outcome following STA-MCA bypass surgery: cerebral blood flow but not vasoreactivity is a predictive parameter

International Nuclear Information System (INIS)

Kume, Norihiko; Hayashida, Kohei; Iwama, Toru; Cho, I.; Matsunaga, N.

1998-01-01

Superficial temporal artery - middle cerebral artery (STA-MCA) bypass surgery might improve the cerebral blood flow (CBF) but fail to reduce the risk of post-surgical events such as ischaemic stroke. In this study, we studied retrospectively whether the risk of post-surgical events corresponded to the change in resting CBF and/or the change in vasoreactivity observed before and after STA-MCA surgery using N-isopropyl-I-123-p-iodoamphetamine ( 123 I-IMP) brain single-photon emission tomography (SPET). 123 I-IMP brain SPET images obtained at rest and following acetazolamide challenge both before and after STA-MCA surgery were studied in 30 patients. Resting CBF was estimated semiquantitatively using the resting count ratios of the middle cerebral artery (MCA) area to the cerebellum. Acetazolamide challenge was assumed to result in an average increase in flow of 40% in the cerebellum. The vasoreactive response was then estimated as the ratio of the change in counts (acetazolamide - rest) to the resting cerebellar counts multiplied by 1.4. We classified 14 patients (50.5±19.3 years) into group I, who had a change in their resting CBF from before to after surgery of >10%, and 16 patients (54.0±18.8 years) into group II, who had a change in their resting CBF from before to after surgery of ≤10%. Oxygen-15 positron emission tomography (PET) studies were performed in five patients from group I and five patients from group II. One post-surgical event occurred in group I while there were eight post-surgical events in group II (P<0.05). Resting CBF improved by 20.4%±7.5% in group I and by 0.9%±6.9% in group II patients after surgery (P<0.001). No significant difference in the improvement in vasoreactivity was observed between group I patients (32.6%±17.7%) and group II patients (24.6%±15.6%) following surgery. Patients in the group I PET subset showed normalization of oxygen extraction fraction (OEF) from 0.59±0.09 before surgery to 0.46±0.06 after surgery (P<0

Cost-utility analysis comparing laparoscopic vs open aortobifemoral bypass surgery

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Krog AH

2017-06-01

Full Text Available Anne Helene Krog,1,2 Mehdi Sahba,3 Erik M Pettersen,4 Torbjørn Wisløff,5,6 Jon O Sundhagen,2 Syed SH Kazmi2 1Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, 2Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Oslo University Hospital, Oslo, 3Department of Vascular Surgery, Østfold Central Hospital, Kalnes, 4Department of Vascular Surgery, Sørlandet Hospital HF, Kristiansand, 5Department of Health Management and Health Economics, University of Oslo, 6Norwegian Institute of Public Health, Oslo, Norway Objectives: Laparoscopic aortobifemoral bypass has become an established treatment option for symptomatic aortoiliac obstructive disease at dedicated centers. Minimally invasive surgical techniques like laparoscopic surgery have often been shown to reduce expenses and increase patients’ health-related quality of life. The main objective of our study was to measure quality-adjusted life years (QALYs and costs after totally laparoscopic and open aortobifemoral bypass. Patients and methods: This was a within trial analysis in a larger ongoing randomized controlled prospective multicenter trial, Norwegian Laparoscopic Aortic Surgery Trial. Fifty consecutive patients suffering from symptomatic aortoiliac occlusive disease suitable for aortobifemoral bypass surgery were randomized to either totally laparoscopic (n=25 or open surgical procedure (n=25. One patient dropped out of the study before surgery. We measured health-related quality of life using the EuroQol (EQ-5D-5L questionnaire at 4 different time points, before surgery and for 6 months during follow-up. We calculated the QALYs gained by using the area under the curve for both groups. Costs were calculated based on prices for surgical equipment, vascular prosthesis and hospital stay. Results: We found a significantly higher increase in QALYs after laparoscopic vs open aortobifemoral bypass surgery, with a difference of 0.07 QALYs, (p=0

NMOS-Based Integrated Modular Bypass for Use in Solar Systems (NIMBUS: Intelligent Bypass for Reducing Partial Shading Power Loss in Solar Panel Applications

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Pieter Bauwens

2016-06-01

Full Text Available NMOS-based Integrated Modular Bypass for Use in Solar systems (NIMBUS is designed as a replacement for the traditional bypass diode, used in common solar panels. Because of the series connection between the individual solar cells, the power output of a photovoltaic (PV panel will drop disproportionally under partial shading. Currently, this is solved by dividing the PV panel into substrings, each with a diode bypass placed in parallel. This allows an alternative current path. However, the diodes still have a significant voltage drop (about 350 mV, and due to the fairly large currents in a panel, the diodes are dissipating power that we would rather see at the output of the panel. The NIMBUS chip, being a low-voltage-drop switch, aims to replace these diodes and, thus, reduce that power loss. NIMBUS is a smart bypass: a completely stand-alone system that detects the failing of one or more cells and activates when necessary. It is designed for a 100-mV voltage drop under a 5-A load current. When two or more NIMBUS chips are placed in parallel, an internal synchronization circuit ensures proper operation to provide for larger load currents. This paper will elaborate on the operation, design and implementation of the NIMBUS chip, as well as on the first measurements.

[Coronary artery bypass grafting without use of cardiopulmonary bypass].

Science.gov (United States)

Mujanović, Emir; Bergsland, Jacob; Hadziselimović, Mehdin; Softić, Muniba; Azabagic, Azur; Stanimirović-Mujanović, Sanja; Kabil, Emir

2002-01-01

Although it is possible to find a number of comparative studies in the world literature discussing the results of coronary artery bypass surgery (CABG) with and without cardiopulmonary bypass (CPB), until now such analysis has not been made in Bosnia and Herzegovina. The main aim of this scientific work was to compare morbidity and mortality, need for blood transfusions, length of stay in the intensive care unit and total length of hospitalisation in two groups of patients operated with these methods. One hundred and four patients with coronary artery disease operated in Cardiovascular Clinic Tuzla, from September, 1998 to September 2002 divided in two groups, were included in this study. There were 52 patients in the first group operated with CPB and 52 patients in the second group operated without CPB. The groups were matched for gender, age, ejection fraction and preoperative risk factors. The incidence of postoperative complications was lower in patients operated without CPB (5.77% vs. 21.15%). The mortality rate was reduced in patients operated without CPB (0.00% vs. 5.76%). There were reduced need for transfusion in patients operated without CPB (0.28 vs. 1.11 units of blood). The average time spent on respirators was shorter in patients operated without CPB (1.50 vs. 4.76 hours). The average time of total hospitalisation was also shorter in patients operated withouth CPB (6.53 vs. 8.13 days). In conclusion CABG without CPB has many advantages compared to the conventional method. Mortality and morbidity are reduced and there is less need for transfusion. The time spent on mechanical ventilation is reduced and less time is spent in intensive care and the total hospitalisation time is also less.

Effect of Levosimendan on Low Cardiac Output Syndrome in Patients With Low Ejection Fraction Undergoing Coronary Artery Bypass Grafting With Cardiopulmonary Bypass

Science.gov (United States)

Caruba, Thibaut; Grosjean, Sandrine; Amour, Julien; Ouattara, Alexandre; Villacorta, Judith; Miguet, Bertrand; Guinet, Patrick; Lévy, François; Squara, Pierre; Aït Hamou, Nora; Carillon, Aude; Boyer, Julie; Boughenou, Marie-Fazia; Rosier, Sebastien; Robin, Emmanuel; Radutoiu, Mihail; Durand, Michel; Guidon, Catherine; Desebbe, Olivier; Charles-Nelson, Anaïs; Menasché, Philippe; Rozec, Bertrand; Girard, Claude; Fellahi, Jean-Luc; Pirracchio, Romain; Chatellier, Gilles

2017-01-01

Importance Low cardiac output syndrome after cardiac surgery is associated with high morbidity and mortality in patients with impaired left ventricular function. Objective To assess the ability of preoperative levosimendan to prevent postoperative low cardiac output syndrome. Design, Setting, and Participants Randomized, double-blind, placebo-controlled trial conducted in 13 French cardiac surgical centers. Patients with a left ventricular ejection fraction less than or equal to 40% and scheduled for isolated or combined coronary artery bypass grafting with cardiopulmonary bypass were enrolled from June 2013 until May 2015 and followed during 6 months (last follow-up, November 30, 2015). Interventions Patients were assigned to a 24-hour infusion of levosimendan 0.1 µg/kg/min (n = 167) or placebo (n = 168) initiated after anesthetic induction. Main Outcomes and Measures Composite end point reflecting low cardiac output syndrome with need for a catecholamine infusion 48 hours after study drug initiation, need for a left ventricular mechanical assist device or failure to wean from it at 96 hours after study drug initiation when the device was inserted preoperatively, or need for renal replacement therapy at any time postoperatively. It was hypothesized that levosimendan would reduce the incidence of this composite end point by 15% in comparison with placebo. Results Among 336 randomized patients (mean age, 68 years; 16% women), 333 completed the trial. The primary end point occurred in 87 patients (52%) in the levosimendan group and 101 patients (61%) in the placebo group (absolute risk difference taking into account center effect, −7% [95% CI, −17% to 3%]; P = .15). Predefined subgroup analyses found no interaction with ejection fraction less than 30%, type of surgery, and preoperative use of β-blockers, intra-aortic balloon pump, or catecholamines. The prevalence of hypotension (57% vs 48%), atrial fibrillation (50% vs 40%), and other adverse

The feasibility of measuring renal blood flow using transesophageal echocardiography in patients undergoing cardiac surgery.

Science.gov (United States)

Yang, Ping-Liang; Wong, David T; Dai, Shuang-Bo; Song, Hai-Bo; Ye, Ling; Liu, Jin; Liu, Bin

2009-05-01

There is no reliable method to monitor renal blood flow intraoperatively. In this study, we evaluated the feasibility and reproducibility of left renal blood flow measurements using transesophageal echocardiography during cardiac surgery. In this prospective noninterventional study, left renal blood flow was measured with transesophageal echocardiography during three time points (pre-, intra-, and postcardiopulmonary bypass) in 60 patients undergoing cardiac surgery. Sonograms from 6 subjects were interpreted by 2 blinded independent assessors at the time of acquisition and 6 mo later. Interobserver and intraobserver reproducibility were quantified by calculating variability and intraclass correlation coefficients. Patients with Doppler angles of >30 degrees (20 of 60 subjects) were eliminated from renal blood flow measurements. Left renal blood flow was successfully measured and analyzed in 36 of 60 (60%) subjects. Both interobserver and intraobserver variability were renal blood flow measurements were good to excellent (intraclass correlation coefficients 0.604-0.999). Left renal arterial luminal diameter for the pre, intra, and postcardiopulmonary bypass phases, ranged from 3.8 to 4.1 mm, renal arterial velocity from 25 to 35 cm/s, and left renal blood flow from 192 to 299 mL/min. In patients undergoing cardiac surgery, it was feasible in 60% of the subjects to measure left renal blood flow using intraoperative transesophageal echocardiography. The interobserver and intraobserver reproducibility of renal blood flow measurements was good to excellent.

Prior failed ipsilateral percutaneous endovascular intervention in patients with critical limb ischemia predicts poor outcome after lower extremity bypass

Science.gov (United States)

Nolan, Brian W.; De Martino, Randall R.; Stone, David H.; Schanzer, Andres; Goodney, Philip P.; Walsh, Daniel W.; Cronenwett, Jack L.

2017-01-01

had a prior ipsilateral bypass (1 year major amputation, 29% vs 20%; P = .022; 1 year graft occlusion, 33% vs 18%; P = .001). Independent multivariate predictors of higher 1-year amputation and graft occlusion rates were prior iPVI, prior ipsilateral bypass, dialysis dependence, prosthetic conduit and distal (tibial and pedal) bypass target. Conclusions Prior iPVI is highly predictive for poor outcome in patients undergoing LEB for CLI with higher 1-year amputation and graft occlusion rates than those without prior revascularization, similar to prior ipsilateral bypass These findings provide information, which may help with the complex decisions surrounding revascularization options in patients with CLI. PMID:21802888

Reinforced long saphenous vein bypass graft for infrainguinal reconstruction procedures: case series and literature review.

LENUS (Irish Health Repository)

Hynes, Niamh

2006-03-01

Poor rehabilitation rates and the high-cost of managing postamputation patients justify an aggressive revascularization policy in critical lower limb ischemia. Endovascular therapy is our first choice for limb salvage in these patients. However there are patients for whom endovascular therapy is not feasible. When bypass is necessary, autologous vein is a superior conduit to synthetic material. However, varicosities usually contraindicate autologous vein bypass because of the risk of aneurysm formation, rupture and increased intimal hyperplasia compared with nonvaricose venous grafts. We report the use of varicosed long saphenous vein (LSV) with external Dacron support in infrainguinal bypass procedures for limb salvage, where endovascular therapy was not feasible. The external Dacron tube was not brought close to the distal anastomotic area itself. With a mean follow-up of 18 months, duplex ultrasonography and computed tomography angiography showed no evidence of stenosis of the reinforced vein segments or aneurysmal degeneration of the residual vein. External reinforcement with Dacron prosthesis allows the use of autogenous greater saphenous veins with varicose dilatation without compromising graft patency and limb salvage.

Autologous blood sequestration using a double venous reservoir bypass circuit and polymerized hemoglobin prime.

Science.gov (United States)

Neragi-Miandoab, Siyamek; Guerrero, J Luis; Vlahakes, Gus J

2002-01-01

Cardiac surgery often necessitates transfusion of homologous blood. Hemoglobin based oxygen carrying solutions (HBOCs) transport oxygen, suggesting use in cardiopulmonary bypass. HBOC was used in a novel oxygenator double-reservoir circuit that permits acute sequestration of a portion of the autologous blood volume during bypass. Two groups of seven mongrel dogs each were studied in an experimental bypass model using global myocardial ischemia and cardioplegia protection: HBOC group, initial venous return drained to a separate reservoir and hypothermic bypass was conducted with HBOC containing perfusate in a second bypass reservoir; Control group, crystalloid prime in a conventional circuit. Hemodynamics and metabolic and hematologic parameters were measured before and 60 min after aortic clamp removal and reinfusion of sequestered autologous blood. Blood gases, base excess, hematocrit, total hemoglobin, and platelet counts were measured. In the HBOC group, metabolic acidosis did not occur, and ventricular function was preserved. Net conservation of platelets was noted at study conclusion: control 33+/-13 x 10(3) per mm3 versus HBOC 48+/-13 x 10(3), p conservation of the platelet mass occurs, a portion of which is not exposed to the deleterious effects of hypothermia and cardiopulmonary bypass.

Experimental investigation on a high subsonic compressor cascade flow

Directory of Open Access Journals (Sweden)

Zhang Haideng

2015-08-01

Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

Coronary artery bypass grafting on the beating heart using the Octopus method

NARCIS (Netherlands)

Thijssens, K. M.; Rodrigus, I. E.; Amsel, B. J.; de Hert, S. G.; Moulijn, A. C.

2000-01-01

STUDY OBJECTIVE: To study the usefulness and effectiveness of off-pump coronary bypass grafting with the Octopus heart stabilizing device. METHOD: The files of thirty-one patients undergoing coronary artery bypass with the aid of the Octopus heart stabilizing device between April 1996 and October

Flow Mode Dependent Partitioning Processes of Preferential Flow Dynamics in Unsaturated Fractures - Findings From Analogue Percolation Experiments

Science.gov (United States)

Kordilla, J.; Noffz, T.; Dentz, M.; Sauter, M.

2017-12-01

To assess the vulnerability of an aquifer system it is of utmost importance to recognize the high potential for a rapid mass transport offered by ow through unsaturated fracture networks. Numerical models have to reproduce complex effects of gravity-driven flow dynamics to generate accurate predictions of flow and transport. However, the non-linear characteristics of free surface flow dynamics and partitioning behaviour at unsaturated fracture intersections often exceed the capacity of classical volume-effective modelling approaches. Laboratory experiments that manage to isolate single aspects of the mass partitioning process can enhance the understanding of underlying dynamics, which ultimately influence travel time distributions on multiple scales. Our analogue fracture network consists of synthetic cubes with dimensions of 20 x 20 x 20 cm creating simple geometries of a single or a cascade of consecutive horizontal fractures. Gravity-driven free surface flow (droplets; rivulets) is established via a high precision multichannel dispenser at flow rates ranging from 1.5 to 4.5 ml/min. Single-inlet experiments show the influence of variable flow rate, atmospheric pressure and temperature on the stability of flow modes and allow to delineate a droplet and rivulet regime. The transition between these regimes exhibits mixed flow characteristics. In addition, multi-inlet setups with constant total infow rates decrease the variance induced by erratic free-surface flow dynamics. We investigate the impacts of variable aperture widths, horizontal offsets of vertical fracture surfaces, and alternating injection methods for both flow regimes. Normalized fracture inflow rates allow to demonstrate and compare the effects of variable geometric features. Firstly, the fracture filling can be described by plug flow. At later stages it transitions into a Washburn-type flow, which we compare to an analytical solution for the case of rivulet flow. Observations show a considerably

EARLY POSTOPERATIVE COMPLICATIONS IN ROUX-EN-Y GASTRIC BYPASS.

Science.gov (United States)

Stoll, Aluisio; Rosin, Leandro; Dias, Mariana Fernandes; Marquiotti, Bruna; Gugelmin, Giovana; Stoll, Gabriela Fanezzi

Roux-en-Y gastric bypass is one of the most common bariatric surgery and leads to considerable weight loss in the first months. To quantify the main early postoperative complications in patients submitted to the gastric bypass. Observational retrospective cohort. Data of 1051 patients with class II obesity associated with comorbidities or class III obesity submitted to the gastric bypass with 30 days of follow-up starting from the date of the surgery. The age average was 36 years with a predominance of females (81.1%). The mean preoperative body mass index was 43 kg/m². The major complication was fistula (2.3%), followed by intestinal obstruction (0.5%) and pulmonary embolism (0.5%). Death occurred in 0.6% of the cases. In the period of 30 days after surgery the overall complication rate was 3.8%; reoperation was necessary in 2.6% and death occurred in 0.6%. Fistula was the main complication and the leading cause of hospitalization in intensive care unit, reoperation and death. Bypass gástrico em Y-de-Roux é uma das operações bariátricas mais comuns e leva a perdas consideráveis de peso já nos primeiros meses. Quantificar as principais complicações pós-operatórias precoces em pacientes submetidos ao bypass gástrico. Coorte retrospectiva observacional. Amostra de 1051 pacientes portadores de obesidade grau II associada à comorbidades ou grau III submetidos ao bypass gástrico com acompanhamento de 30 dias a partir da data da operação. A idade média dos pacientes foi de 36 anos com predominância de mulheres (81,1%). O índice de massa corporal pré-operatório médio foi de 43 kg/m². A principal complicação foi fístula (2,3%), seguida de obstrução intestinal (0,5%) e tromboembolismo pulmonar (0,5%). Óbito ocorreu em 0,6% dos casos. No período de 30 dias de pós-operatório a taxa geral de complicações foi de 3,8%; a de reoperação de 2,6% e óbito em 0,6%. A fístula foi a principal complicação e a principal causa de internamento em

A High-Current, Stable Nonaqueous Organic Redox Flow Battery

Energy Technology Data Exchange (ETDEWEB)

Wei, Xiaoliang; Duan, Wentao; Huang, Jinhua; Zhang, Lu; Li, Bin; Reed, David; Xu, Wu; Sprenkle, Vincent; Wang, Wei

2016-10-14

Nonaqueous redox flow batteries are promising in pursuit of high-energy storage systems owing to the broad voltage window, but currently are facing key challenges such as poor cycling stability and lack of suitable membranes. Here we report a new nonaqueous all-organic flow chemistry that demonstrates an outstanding cell cycling stability primarily because of high chemical persistency of the organic radical redox species and their good compatibility with the supporting electrolyte. A feasibility study shows that Daramic® and Celgard® porous separators can lead to high cell conductivity in flow cells thus producing remarkable cell efficiency and material utilization even at high current operations. This result suggests that the thickness and pore size are the key performance-determining factors for porous separators. With the greatly improved flow cell performance, this new flow system largely addresses the above mentioned challenges and the findings may greatly expedite the development of durable nonaqueous flow batteries.

Endovascular Placement of an Extraluminal Femoropopliteal Bypass Graft in Human Cadavers

International Nuclear Information System (INIS)

Maynar, Manuel; Llorens, Rafael; Lopez-Sanchez, Carmen; Garcia-Martinez, Virginio; Qian Zhong; Lopera, Jorge; Castaneda, Wilfrido R.

2005-01-01

Purpose. A method to create an extraluminal femoropopliteal bypass graft using endovascular techniques was evaluated in situ on cadaver extremities in an attempt to develop a minimally invasive alternative technique for the management of infrainguinal occlusive arterial disease. Methods. The endovascular placement of an extraluminal femoropopliteal bypass graft was undertaken in 5 cadaver legs. Following percutaneous access to the popliteal artery (PA) or common femoral artery (CFA), a Rosch-Uchida needle was used to perforate the vascular wall, followed by the creation of an extraluminal tract using a looped wire and catheter. Once the desired level was reached the needle was again used to perforate the vascular wall of the proximal superficial femoral artery (SFA) or PA depending on the access used. Self-expanding expanded polytetrafluoroethylene (ePTFE) stent-grafts were then deployed to establish the extraluminal femoropopliteal bypass connecting the two arterial puncture sites. Following dilatation of the stent-graft, angiography was performed to assess the endoprostheses and to look for contrast leaks. Results. Technical success was achieved in all 5 legs. Procedure time varied from 15 to 30 min. The angiographic studies performed immediately after completion of the bypass procedure showed patency of the grafts with no evidence of kinking or leakage in any of the cases. Conclusion. This study has proved that the endovascular placement of an extraluminal femoropopliteal bypass graft in human cadaver legs using endovascular techniques under fluoroscopic control is technically feasible

[Prevention of side effects and complications after operation for partial ileal bypass].

Science.gov (United States)

Mirchuk, K K; Sedletskiĭ, Iu I

2014-01-01

Side effects and complications of the application of partial ileal bypass used for dislipidemia were analyzed in 162 patients with atherosclerosis. It was shown, that the partial ileal bypass operation could lead to the development of series of undesirable side effects such as diarrhea, hypovitaminosis B12, off-state intestine enteritis. The application of modification of partial ileal bypass such as formation of ileo-ileoanastomosis 5-6 cm long near ileocecal valve with the maintenance of its functions disposed the diarrhea and minimized the risk of the development of hypovitaminosis B12 after operation. It is possible to prevent the development of enteritis of off-state loop of the small intestine by using microanastomosis between off-state and functioning iliac intestine. The partial ileal bypass operation didn't influence on body weight, wouldn't increase the risk of stone formation in the gallbladder and kidneys. The risk of the development of hypovitaminosis B12 is minimal after operation.

Construct exploit constraint in crash analysis by bypassing canary

Science.gov (United States)

Huang, Ning; Huang, Shuguang; Huang, Hui; Chang, Chao

2017-08-01

Selective symbolic execution is a common program testing technology. Developed on the basis of it, some crash analysis systems are often used to test the fragility of the program by constructing exploit constraints, such as CRAX. From the study of crash analysis based on symbolic execution, this paper find that this technology cannot bypass the canary stack protection mechanisms. This paper makes the improvement uses the API hook in Linux. Experimental results show that the use of API hook can effectively solve the problem that crash analysis cannot bypass the canary protection.

The value of 201Tl myocardial scintigraphy and of computed tomography for predicting the effectiveness of coronary artery bypass surgery

International Nuclear Information System (INIS)

Krosse, B.; Duck, H.J.; Neumann, G.; Huppert, P.; Schulz, H.G.; Lindenau, K.F.

1986-01-01

50 male patients with stenosing coronary artery sclerosis and an indication for coronary artery bypass surgery were subjected to pre- and postsurgical 201 Tl scintigraphy and postsurgical computed tomography. Control by angiography was carried out in six cases. Scintigraphy revealed an improved myocardial perfusion in 30 patients, whereas it was unchanged in 15 and deteriorated in 5 patients. Angiography exhibited two cases of graft occlusion, one case of bad run off, and two cases of progressing arteriosclerosis under intact graft. Computed tomography showed that 83 bypasses of the 50 patients were occluded in 6 cases, which was confirmed by angiography in 3 cases. The investigation demonstrates the high value of the two non-invasive methods for the control of bypass patency. (author)

Cardiopulmonary bypass in pregnancy

OpenAIRE

Mukul Chandra Kapoor

2014-01-01

Cardiac surgery carried out on cardiopulmonary bypass (CPB) in a pregnant woman is associated with poor neonatal outcomes although maternal outcomes are similar to cardiac surgery in non-pregnant women. Most adverse maternal and fetal outcomes from cardiac surgery during pregnancy are attributed to effects of CPB. The CPB is associated with utero-placental hypoperfusion due to a number of factors, which may translate into low fetal cardiac output, hypoxia and even death. Better maternal and f...

Basics of cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Manjula Sarkar

2017-01-01

Full Text Available Cardiopulmonary bypass (CPB provides a bloodless field for cardiac surgery. It incorporates an extracorporeal circuit to provide physiological support in which venous blood is drained to a reservoir, oxygenated and sent back to the body using a pump. Team effort between surgeon, perfusionist and anaesthesiologist is paramount for the successful use of CPB. However, it also has its share of complications and strategies to reduce these complications are the area of the current research.

Bypassing BDD Construction for Reliability Analysis

DEFF Research Database (Denmark)

Williams, Poul Frederick; Nikolskaia, Macha; Rauzy, Antoine

2000-01-01

In this note, we propose a Boolean Expression Diagram (BED)-based algorithm to compute the minimal p-cuts of boolean reliability models such as fault trees. BEDs make it possible to bypass the Binary Decision Diagram (BDD) construction, which is the main cost of fault tree assessment....

Bypassing agent prophylaxis in people with hemophilia A or B with inhibitors.

Science.gov (United States)

Chai-Adisaksopha, Chatree; Nevitt, Sarah J; Simpson, Mindy L; Janbain, Maissaa; Konkle, Barbara A

2017-09-25

People with hemophilia A or B with inhibitors are at high risk of bleeding complications. Infusion of bypassing agents, such as recombinant activated FVII (rFVIIa) and plasma-derived activated prothrombin complex concentrate, are suggested as alternative therapies to factor VIII (haemophilia A) or IX (haemophilia B) for individuals who no longer respond to these treatments because they develop inhibitory antibodies. The ultimate goal of treatment is to preserve the individual's joints, otherwise destroyed by recurrent bleeds. To assess the effects of bypassing agent prophylaxis to prevent bleeding in people with hemophilia A or B and inhibitors. We searched for relevant studies from the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched trial registries (16 February 2017) and bibliographic references of retrieved studies were reviewed for potential articles to be included in the review.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register: 12 December 2016. We included randomized and quasi-randomized controlled studies (cross-over or parallel design) evaluating the effect of prophylaxis treatment with bypassing agents compared with on-demand treatment, or studies evaluating the effects of high-dose compared with low-dose prophylaxis in males of any age with hemophilia with inhibitors. Two authors independently selected studies and extracted data and assessed the risk of bias according to standard Cochrane criteria. They assessed the quality of the evidence using the GRADE criteria. We included four randomized studies (duration 7 to 15 months) involving 116 males. Risk of bias was judged to be high in two studies due to the open-label study design and in one study due to attrition bias.Two studies

Video-assisted minimally invasive coronary operations without cardiopulmonary bypass : A multicenter study

NARCIS (Netherlands)

Benetti, F; Mariani, MA; Sani, G; Boonstra, PW; Grandjean, JG; Giomarelli, P; Toscano, M

1996-01-01

Objective: The need to avoid the risks associated with cardiopulmonary bypass has led to the interest in coronary operations without cardiopulmonary bypass, Patients and methods: From April 1994 to September 1995, 44 patients (mean age 63.3 +/- 10.0 years, range 43 to 83 years) were selected for

Progress in Management of Sediment Bypassing at Coastal Inlets: Natural Bypassing, Weir Jetties, Jetty Spurs, and Engineering Aids in Design

National Research Council Canada - National Science Library

Seabergh, William C; Kraus, Nicholas C

2003-01-01

.... Artificial bypassing mimics or preserves the pathways of sediment in the littoral zone and harmonizes the requirement for deepening navigation channels within the context of the natural sediment...

Pattern and predictors of dual antiplatelet use after coronary artery bypass graft surgery.

Science.gov (United States)

Mori, Makoto; Shioda, Kayoko; Yun, James J; Mangi, Abeel A; Darr, Umer; Geirsson, Arnar

2018-02-01

Resumption of dual antiplatelet therapy after coronary artery bypass grafting in patients presenting with acute coronary syndrome is recommended, but the current practice pattern in the United States remains unknown. We aimed to investigate the current pattern of dual antiplatelet therapy use after coronary artery bypass grafting at the Yale-New Haven Hospital. We conducted a single-center retrospective review of patients who presented with acute coronary syndrome and underwent coronary artery bypass grafting between 2014 and 2016. The primary outcome was hospital discharge with dual antiplatelet therapy. Mixed-effect multivariate logistic regression was used to evaluate predictors of dual antiplatelet therapy use or nonuse, accounting for surgeon-specific preference. The discriminatory ability of the model was evaluated with receiver operating characteristics analysis. Of 572 patients included, only 29% were discharged with dual antiplatelet therapy. In the mixed-effect multivariate model isolating surgeon preferences, increase in age (odds ratio, 0.95; 95% confidence interval, 0.92-0.98; P dual antiplatelet therapy use. Off-pump coronary artery bypass grafting compared with on-pump coronary artery bypass grafting was associated with increased odds of dual antiplatelet therapy use (odds ratio, 31.5; 95% confidence interval, 12.8-77.2; P dual antiplatelet therapy use in patients with acute coronary syndrome who underwent coronary artery bypass grafting was low and variable among surgeons. The use or nonuse was guided by previously established risk factors of recurrent ischemia and bleeding, along with surgeon preference. Published by Elsevier Inc.

Hedonic changes in food choices following Roux-en-Y gastric bypass

DEFF Research Database (Denmark)

Hansen, Thea Toft; Jakobsen, Tine Anette; Nielsen, Mette Søndergaard

2016-01-01

It has been suggested that a shift in food choices leading to a diet with a lower energy density plays an important role in successful weight loss after Roux-en-Y gastric bypass (RYGB) surgery. A decreased hedonic drive to consume highly palatable foods may explain these changes in eating behavio...... to consume highly palatable foods. Still, in order to fully understand the complexity of these changes, we need studies combining sociological and psychological approaches with objective measures of actual food choices examining different measures of hedonic drive....

Gage for gas flow measurement especially in gas-suction pipes

International Nuclear Information System (INIS)

Renner, K.; Stegmanns, W.

1978-01-01

The gage utilizes the differential pressure given by a differential pressure producer to generate, in a bypass, a partial gas flow measured by means of a direct-reading anemometer of windmill type. The partial gas flow is generated between pressure pick-up openings in the gas-suction pipe in front of a venturi insert and pressure pick-up openings at the bottleneck of the venturi insert. The reading of the anemometer is proportional to the main gas flow and independent of the variables of state and the properties of the gases to be measured. (RW) [de

Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

Science.gov (United States)

Sammy, Mo

2010-01-01

Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

Rumen bypass nutrients: Manipulation and implications

International Nuclear Information System (INIS)

Leng, R.A.; Nolan, J.V.; Preston, T.R.

1983-01-01

The feeds available for ruminants in developing countries are either agro-industrial by-products or specially grown forage crops. Many of these feeds are low in protein and require supplementation with non-protein N (NPN) to maintain efficient rumen function and digestibility. The principles for utilizing high energy, low protein feeds by ruminants are discussed in relation to the supply of NPN, the establishment of efficient rumen function, maximizing feed intake by means of supplements, and increasing total energy and protein intake by using supplements which bypass the rumen. To illustrate it the application of these principles to feeding systems based on molasses, chopped whole sugar cane and derinded sugar cane is discussed. The implications of the principles in increasing the feeding value of straw are also discussed. (author)

High speed digital holographic interferometry for hypersonic flow visualization

Science.gov (United States)

Hegde, G. M.; Jagdeesh, G.; Reddy, K. P. J.

2013-06-01

Optical imaging techniques have played a major role in understanding the flow dynamics of varieties of fluid flows, particularly in the study of hypersonic flows. Schlieren and shadowgraph techniques have been the flow diagnostic tools for the investigation of compressible flows since more than a century. However these techniques provide only the qualitative information about the flow field. Other optical techniques such as holographic interferometry and laser induced fluorescence (LIF) have been used extensively for extracting quantitative information about the high speed flows. In this paper we present the application of digital holographic interferometry (DHI) technique integrated with short duration hypersonic shock tunnel facility having 1 ms test time, for quantitative flow visualization. Dynamics of the flow fields in hypersonic/supersonic speeds around different test models is visualized with DHI using a high-speed digital camera (0.2 million fps). These visualization results are compared with schlieren visualization and CFD simulation results. Fringe analysis is carried out to estimate the density of the flow field.

Noninvasive detection of coronary artery bypass graft patency by intravenous electron beam computed tomographic angiography.

Science.gov (United States)

Yamakami, Shoji; Toyama, Junji; Okamoto, Mitsuhiro; Matsushita, Toyoaki; Murakami, Yoshimasa; Ogata, Masaki; Ito, Shigenori; Fukutomi, Tatsuya; Okayama, Naotsuka; Itoh, Makoto

2003-11-01

This study evaluates the usefullness of intravenous electron beam computed tomographic angiography (EBA) for the detection of coronary artery bypass graft patency in 43 patients (33 men and 10 women, mean age, 65 years) who had coronary artery bypass graft surgery. EBA was performed a few days before selective bypass graft angiography (SGA). Forty axial cross-sections of angiographic images of the heart were acquired consecutively by an electrocardiographic trigger signal at 40% of the RR interval, which corresponds to the end-systolic phase. EBA data were reconstructed as a three-dimensional shaded surface display of the heart and bypass grafts. Detectability of the patency of bypass gratis was evaluated, taking selective angiographic images of the bypass grafts as a gold standard. One hundred and nine grafts (96%) out of 114 grafts were subjected to evaluation: 37 grafts were left internal mammary artery grafts (LIMA), 7 were right internal mammary artery grafts (RIMA), 6 were gastroepiploic artery grafts (GEA), 7 were free gastroepiploic artery grafts with venous drainage (free-GEA), 7 were radial artery grafts (RAG), and 45 were saphenous vein gratis (SVG). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EBA were 98%, 100%, 100%, 91%, and 98%, respectively. EBA sampled at the end-systolic period was determined to be useful for the detection of coronary artery bypass graft patency and occlusion.

Rat muscle blood flows during high-speed locomotion

International Nuclear Information System (INIS)

Armstrong, R.B.; Laughlin, M.H.

1985-01-01

We previously studied blood flow distribution within and among rat muscles as a function of speed from walking (15 m/min) through galloping (75 m/min) on a motor-driven treadmill. The results showed that muscle blood flows continued to increase as a function of speed through 75 m/min. The purpose of the present study was to have rats run up to maximal treadmill speeds to determine if blood flows in the muscles reach a plateau as a function of running speed over the animals normal range of locomotory speeds. Muscle blood flows were measured with radiolabeled microspheres at 1 min of running at 75, 90, and 105 m/min in male Sprague-Dawley rats. The data indicate that even at these relatively high treadmill speeds there was still no clear evidence of a plateau in blood flow in most of the hindlimb muscles. Flows in most muscles continued to increase as a function of speed. These observed patterns of blood flow vs. running speed may have resulted from the rigorous selection of rats that were capable of performing the high-intensity exercise and thus only be representative of a highly specific population of animals. On the other hand, the data could be interpreted to indicate that the cardiovascular potential during exercise is considerably higher in laboratory rats than has normally been assumed and that inadequate blood flow delivery to the muscles does not serve as a major limitation to their locomotory performance

The impact of heparin-coated circuits on hemodynamics during and after cardiopulmonary bypass

NARCIS (Netherlands)

de Vroege, R; Huybregts, R; van Oeveren, W; van Klarenbosch, J; Linley, G; Mutlu, J; Jansen, E; Hack, E; Eijsman, L; Wildevuur, C

This study was performed to investigate if heparin-coated extracorporeal circuits can reduce the systemic inflammatory reaction with the subsequent release of vasoactive substances during and after cardiopulmonary bypass. Fifty-one patients scheduled for coronary artery bypass grafting were perfused

Follow-up of coronary artery bypass graft patency: diagnostic efficiency of high-pitch dual-source 256-slice MDCT findings.

Science.gov (United States)

Yuceler, Zeyneb; Kantarci, Mecit; Yuce, Ihsan; Kizrak, Yesim; Bayraktutan, Ummugulsum; Ogul, Hayri; Kiris, Adem; Celik, Omer; Pirimoglu, Berhan; Genc, Berhan; Gundogdu, Fuat

2014-01-01

Our aim was to evaluate the diagnostic accuracy of 256-slice, high-pitch mode multidetector computed tomography (MDCT) for coronary artery bypass graft (CABG) patency. Eighty-eight patients underwent 256-slice MDCT angiography to evaluate their graft patency after CABG surgery using a prospectively synchronized electrocardiogram in the high-pitch spiral acquisition mode. Effective radiation doses were calculated. We investigated the diagnostic accuracy of high-pitch, low-dose, prospective, electrocardiogram-triggering, dual-source MDCT for CABG patency compared with catheter coronary angiography imaging findings. A total of 215 grafts and 645 vessel segments were analyzed. All graft segments had diagnostic image quality. The proximal and middle graft segments had significantly (P < 0.05) better mean image quality scores (1.18 ± 0.4) than the distal segments (1.31 ± 0.5). Using catheter coronary angiography as the reference standard, high-pitch MDCT had the following sensitivity, specificity, positive predictive value, and negative predictive value of per-segment analysis for detecting graft patency: 97.1%, 99.6%, 94.4%, and 99.8%, respectively. In conclusion, MDCT can be used noninvasively with a lower radiation dose for the assessment of restenosis in CABG patients.

Effects of intestinal bypass surgery on appetite, food intake, and body weight in obese and lean rats.

Science.gov (United States)

Sclafani, A; Koopmans, H S; Vasselli, J R; Reichman, M

1978-04-01

Jejunoileal bypass surgery or sham surgery was performed in female rats made obese with ventromedial hypothalamic (VMH) knife cuts, and in lean control rats. After bypass surgery, the VMH rats underate and lost weight until they reached the body weight of the control sham rats, and they then maintained their weight at control levels. Bypass surgery in lean rats produced much smaller reductions in food intake and body weight. Both bypass groups initially consumed less of a sucrose solution and milk diet during 1 h/day tests, but their intakes returned to near normal levels during the second postoperative month. Reconnection of the intestinal tract in the VMH-bypass rats led to renewed hyperphagia and return to obese body weights. A second experiment revealed that bypass surgery reduces food intake and body weight in genetically obese (fatty) rats, but this effect is not as pronounced as that displayed by VMH rats. These results confirm recent clinical observations that reduced appetite and caloric intake are the major causes of the weight loss produced by intestinal bypass surgery.

Turbulent behaviour of non-cohesive sediment gravity flows at unexpectedly high flow density

Science.gov (United States)

Baker, Megan; Baas, Jaco H.; Malarkey, Jonathan; Kane, Ian

2016-04-01

Experimental lock exchange-type turbidity currents laden with non-cohesive silica-flour were found to be highly dynamic at remarkably high suspended sediment concentrations. These experiments were conducted to produce sediment gravity flows of volumetric concentrations ranging from 1% to 52%, to study how changes in suspended sediment concentration affects the head velocities and run-out distances of these flows, in natural seawater. Increasing the volumetric concentration of suspended silica-flour, C, up to C = 46%, within the flows led to a progressive increase in the maximum head velocity. This relationship suggests that suspended sediment concentration intensifies the density difference between the turbulent suspension and the ambient water, which drives the flow, even if almost half of the available space is occupied by sediment particles. However, from C = 46% to C = 52% a rapid reduction in the maximum head velocity was measured. It is inferred that at C = 46%, friction from grain-to-grain interactions begins to attenuate turbulence within the flows. At C > 46%, the frictional stresses become progressively more dominant over the turbulent forces and excess density, thus producing lower maximum head velocities. This grain interaction process started to rapidly reduce the run-out distance of the silica-flour flows at equally high concentrations of C ≥ 47%. All flows with C tank, but the head velocities gradually reduced along the tank. Bagnold (1954, 1963) estimated that, for sand flows, grain-to-grain interactions start to become important in modulating turbulence at C > 9%. Yet, the critical flow concentration at which turbulence modulation commenced for these silica-flour laden flows appeared to be much higher. We suggest that Bagnold's 9% criterion cannot be applied to flows that carry fine-grained sediment, because turbulent forces are more important than dispersive forces, and frictional forces start to affect the flows only at concentrations just

The effect of laparoscopic Roux-en-Y gastric bypass on fibromyalgia.

Science.gov (United States)

Saber, Alan A; Boros, Michael J; Mancl, Tara; Elgamal, Mohamed H; Song, Susrap; Wisadrattanapong, Therawat

2008-06-01

Fibromyalgia is a chronic debilitating disorder affecting 3-5% of the US population. Treatment of this disorder is a challenge. The incidental finding of improvement of fibromyalgia following laparoscopic Roux-en-Y gastric bypass stimulated us to study this phenomenon. A retrospective chart review of patients with fibromyalgia who underwent laparoscopic Roux-en-Y gastric bypass. Postoperative decrease in median of BMI from 49.4 to 29.7 was significant (p value = 0.0010). This was associated with statistically significant improvement in median of pain score (p value = 0.0010) and median points of tenderness (p value = 0.0010). Significant weight loss following laparoscopic Roux-en-Y gastric bypass is associated with resolution or improvement of fibromyalgia. Consequently, the bariatric surgeon should be a member of the multidisciplinary team approach for treating fibromyalgia.

Perioperative outcomes in minimally invasive direct coronary artery bypass versus off-pump coronary artery bypass with sternotomy.

Science.gov (United States)

Tekin, Ali İhsan; Arslan, Ümit

2017-09-01

Surgical treatment of isolated left anterior descending coronary artery disease can be performed with either minimally invasive direct coronary artery bypass via a left anterior thoracotomy (MIDCAB) or off-pump coronary artery bypass via a median sternotomy (OPCAB). To compare the perioperative outcomes of patients undergoing MIDCAB or OPCAB surgery. Patients who underwent either MIDCAB or OPCAB for isolated left anterior descending (LAD) coronary artery disease between October 2013 and December 2015 were retrospectively evaluated. Operations were carried out by the same surgical team. Preoperative, intraoperative and postoperative data of the patients were recorded for analyses. Twenty-three patients (7 females, 16 males) underwent MIDCAB surgery, and 24 patients (4 female, 20 males) underwent OPCAB surgery. The two groups were comparable regarding preoperative patient characteristics. Duration of mechanical ventilation (5.1 ±0.7 h vs. 6.6 ±0.9 h), intensive care unit stay (19.4 ±2.5 h vs. 45.8 ±5.4 h) and hospital stay (4.3 ±0.4 days vs. 5.6 ±0.8 days) were significantly shorter in the MIDCAB group (p < 0.01). Patients in the OPCAB group required significantly more blood transfusions (1.83 ±0.38 units vs. 0.17 ±0.38 units) and fresh frozen plasma use (2.33 ±0.96 units vs. 0.69 ±0.76 units) (p < 0.01). Conversion to sternotomy was not required in the MIDCAB group. There was no mortality, conversion to cardiopulmonary bypass or serious complication in either group. We believe that the MIDCAB technique is more advantageous than the OPCAB technique in the treatment of patients with a critical LAD lesion.

High-performance liquid chromatography assay using ultraviolet detection for urinary quantification of milrinone concentrations in cardiac surgery patients undergoing cardiopulmonary bypass.

Science.gov (United States)

Gavra, Paul; Nguyen, Anne Q N; Beauregard, Natasha; Denault, André Y; Varin, France

2014-08-01

An analytical assay using liquid-liquid extraction and high-performance liquid chromatography with ultraviolet detection was developed for the quantification of total (conjugated and unconjugated) urinary concentrations of milrinone after the inhalation of a 5 mg dose in 15 cardiac patients undergoing cardiopulmonary bypass. Urine samples (700 μL) were extracted with ethyl-acetate and subsequently underwent acid back-extraction before and after deconjugation by mild acid hydrolysis. Milrinone was separated on a strong cation exchange analytical column. The mobile phase consisted of a constant mixture of acetonitrile:tetrahydrofurane-NaH2 PO4 buffer (40:60 v/v, pH 3.0). Thirteen calibration curves were linear in the concentration range of 31.25-4000 ng/mL, using olprinone as the internal standard (r(2) range 0.9911-0.9999, n = 13). Mean milrinone recovery and accuracy were respectively 85.2 ± 3.1% and ≥93%. Intra- and inter-day precisions (coefficients of variation) were ≤5% and ≤8%, respectively. Over a 24 h collection period, the cumulative urinary milrinone recovered from 15 patients was 26.1 ± 7.7% of the nominal 5 mg dose administered. The relative amount of milrinone glucuronic acid conjugate was negligible in the urine of patients undergoing cardiopulmonary bypass This method proved to be reliable, specific and accurate to determine the cumulative amount of total milrinone recovered in urine after inhalation. Copyright © 2014 John Wiley & Sons, Ltd.

Optimal Power Flow Pursuit

Energy Technology Data Exchange (ETDEWEB)

Dall' Anese, Emiliano; Simonetto, Andrea

2018-03-01

This paper considers distribution networks featuring inverter-interfaced distributed energy resources, and develops distributed feedback controllers that continuously drive the inverter output powers to solutions of AC optimal power flow (OPF) problems. Particularly, the controllers update the power setpoints based on voltage measurements as well as given (time-varying) OPF targets, and entail elementary operations implementable onto low-cost microcontrollers that accompany power-electronics interfaces of gateways and inverters. The design of the control framework is based on suitable linear approximations of the AC power-flow equations as well as Lagrangian regularization methods. Convergence and OPF-target tracking capabilities of the controllers are analytically established. Overall, the proposed method allows to bypass traditional hierarchical setups where feedback control and optimization operate at distinct time scales, and to enable real-time optimization of distribution systems.

Modulation method of scroll compressor based on suction gas bypass

International Nuclear Information System (INIS)

Wang Baolong; Han Linjun; Shi Wenxing; Li Xianting

2012-01-01

The air conditioners and heat pumps tend to work in much mild environments and part load situations rather than provide the rated full capacity under severe rated testing conditions. Both the capacity and inner compression ratio of the compressor should be regulated according to the working condition for higher energy efficiency and occupants’ comfort. A potential modulating technology of the scroll compressor, suction gas bypass, is investigated in this paper. The principle and operation method are illuminated and the adaptability is validated by experiments and simulations. As a conclusion, an appropriate suction gas bypass can reduce the inner compression loss of the scroll compressor under over compression conditions, enhance the system COP and also largely decrease the heating/cooling capacity of the refrigeration/heat pump system. - Highlights: ► Suction gas bypass (SGB) is an effective regulating method of scroll compressor. ► SGB reduces the inner compression loss under over compression conditions. ► SGB largely decreases the heating/cooling capacity of the refrigeration system.

Simultaneous nephrectomy and coronary artery bypass grafting through extended sternotomy

Directory of Open Access Journals (Sweden)

Budrikis Algimantas

2012-08-01

Full Text Available Abstract Background The advances in surgical techniques, resuscitation and anesthesiology support over the last years have allowed simultaneous thoracic and abdominal operations to be made for cancer and concomitant severe heart vessel disease relieving the patient from several diseases simultaneously and achieving long lasting remission or cure. Clinical case A simultaneous nephrectomy and coronary artery bypass grafting procedure through extended sternotomy is reported. A 63-year-old man with severe coronary artery disease was found to have renal carcinoma. Diagnosis Postoperative pathological investigation of the tumor revealed the presence of renal cell carcinoma pT3a N0 M0, G2. Coronarography revealed advanced three-vessel coronary artery disease. Treatment We successfully performed a simultaneous curative surgery for renal carcinoma and coronary artery bypass graft surgery under cardiopulmonary bypass using a novel technique of extended sternotomy. Simultaneous surgery thus appears to be a beneficial and safe approach for the treatment of coronary artery disease and resectable renal cancer in carefully selected patients.

Randomised trial of endoscopic endoprosthesis versus operative bypass in malignant obstructive jaundice

DEFF Research Database (Denmark)

Andersen, J R; Sørensen, S M; Kruse, A

1989-01-01

In patients with obstructive jaundice caused by malignant stricture of the extrahepatic bile duct we compared survival time, complication rates, hospitalisation requirements, and quality of life after palliation by endoscopic endoprosthesis or bypass surgery. During diagnostic endoscopic cholangi......In patients with obstructive jaundice caused by malignant stricture of the extrahepatic bile duct we compared survival time, complication rates, hospitalisation requirements, and quality of life after palliation by endoscopic endoprosthesis or bypass surgery. During diagnostic endoscopic...... in survival between treatment groups or randomisation groups. No differences were found when other variables were compared. We conclude, that palliation of obstructive jaundice in malignant bile duct obstruction with endoscopically introduced endoprosthesis is as effective as operative bypass....

Ketosis After Cardiopulmonary Bypass in Children Is Associated With an Inadequate Balance Between Oxygen Transport and Consumption.

Science.gov (United States)

Klee, Philippe; Arni, Delphine; Saudan, Sonja; Schwitzgebel, Valérie M; Sharma, Ruchika; Karam, Oliver; Rimensberger, Peter C

2016-09-01

Hyperglycemia after cardiac surgery and cardiopulmonary bypass in children has been associated with worse outcome; however, causality has never been proven. Furthermore, the benefit of tight glycemic control is inconsistent. The purpose of this study was to describe the metabolic constellation of children before, during, and after cardiopulmonary bypass, in order to identify a subset of patients that might benefit from insulin treatment. Prospective observational study, in which insulin treatment was initiated when postoperative blood glucose levels were more than 12 mmol/L (216 mg/dL). Tertiary PICU. Ninety-six patients 6 months to 16 years old undergoing cardiac surgery with cardiopulmonary bypass. None. Metabolic tests were performed before anesthesia, at the end of cardiopulmonary bypass, at PICU admission, and 4 and 12 hours after PICU admission, as well as 4 hours after initiation of insulin treatment. Ketosis was present in 17.9% patients at the end of cardiopulmonary bypass and in 31.2% at PICU admission. Young age was an independent risk factor for this condition. Ketosis at PICU admission was an independent risk factor for an increased difference between arterial and venous oxygen saturation. Four hours after admission (p = 0.05). Insulin corrected ketosis within 4 hours. In this study, we found a high prevalence of ketosis at PICU admission, especially in young children. This was independently associated with an imbalance between oxygen transport and consumption and was corrected by insulin. These results set the basis for future randomized controlled trials, to test whether this subgroup of patients might benefit from increased glucose intake and insulin during surgery to avoid ketosis, as improving oxygen transport and consumption might improve patient outcome.

Fluoropolymer-coated dacron versus PTFE grafts for femorofemoral crossover bypass: randomised trial

DEFF Research Database (Denmark)

Eiberg, JP; Røder, Ole Christian; Stahl-Madsen, M

2006-01-01

To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery.......To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery....

Replicative bypass repair of ultraviolet damage to DNA of mammalian cells: caffeine sensitive and caffeine resistant mechanism

International Nuclear Information System (INIS)

Fujiwara, Y.; Tatsumi, M.

1976-01-01

Replicative bypass repair of UV damage to DNA was studied in a wide variaty of human, mouse and hamster cells in culture. Survival curve analysis revealed that in established cell lines (mouse L, Chinese hamster V79, HeLa S3 and SV40-transformed xeroderma pigmentosum (XP), post-UV caffeine treatment potentiated cell killing by reducing the extrapolation number and mean lethal UV fluence (Do). In the Do reduction as the result of random inactivation by caffeine of sensitive repair there were marked clonal differences among such cell lines, V79 being most sensitive to caffeine potentiation. However, other diploid cell lines (normal human, excision-defective XP and Syrian hamster) exhibited no obvious reduction in Do by caffeine. In parallel, alkaline sucrose sedimentation results showed that the conversion of initially smaller segments of DNA synthesized after irradiation with 10 J/m 2 to high-molecular-weight DNA was inhibited by caffeine in transformed XP cells, but not in the diploid human cell lines. Exceptionally, diploid XP variants had a retarded ability of bypass repair which was drastically prevented by caffeine, so that caffeine enhanced the lethal effect of UV. Neutral CsCl study on the bypass repair mechanism by use of bromodeoxyuridine for DNA synthesis on damaged template suggests that the pyrimodine dimer acts as a block to replication and subsequently it is circumvented presumably by a new process involving replicative bypassing following strand displacement, rather than by gap-filling de novo. This mechanism worked similarly in normal and XP cells, whether or not caffeine was present, indicating that excision of dimer is not always necessary. However, replicative bypassing became defective in XP variant and transformed XP cells when caffeine was present. It appears, therefore, that the replicative bypass repair process is either caffeine resistant or sensitive, depending on the cell type used, but not necessarily on the excision repair capability

Problems of Cold Agglutinins in Cardiac Surgery: How to Manage Cardiopulmonary Bypass and Myocardial Protection

Directory of Open Access Journals (Sweden)

Kambiz Alizadeh

2014-02-01

Full Text Available Cold agglutinins are of unique relevance in cardiac surgerybecause of the use of hypothermic cardiopulmonary bypass (CPB. Cold autoimmune diseases are defined by the presence of abnormal circulating proteins (usually IgM or IgA antibodies that agglutinate in response to a decrease in body temperature. These disorders include cryoglobulinemia and cold hemagglutinin disease.Immunoglobulin M autoantibodies to red blood cells, which activateat varying levels of hypothermia, can cause catastrophic hemagglutination,microvascular thrombosis, or hemolysis. Management of anesthesia in these patients includes strict maintenance of normothermia. Patients scheduled for the surgery requiring cardiopulmonary bypass present significant challenges. Use of systemic hypothermia may be contraindicated, and cold cardioplegia solutions may precipitate intracoronary hemagglutination with consequent thrombosis, ischemia, or infarction. Management of CPB andmyocardial protection requires individualized planning. We describea case of MV repair and CABG in a patient with high titercold agglutinins and high thermal amplitude for antibody activation.Normothermic CPB and continuous warm blood cardioplegia weresuccessfully used.

Does the Ventrica magnetic vascular positioner (MVP) for coronary artery bypass grafting significantly alter local fluid dynamics? A numeric study.

Science.gov (United States)

Morbiducci, U; Lemma, M; Ponzini, R; Boi, A; Bondavalli, L; Antona, C; Montevecchi, F M; Redaelli, A

2007-07-01

Automatic devices have been recently introduced to make the anastomosis procedure quick and efficient when creating a coronary bypass on the beating heart. However, the implantation of these devices could modify the graft configuration, consistently affecting the hemodynamics usually found in the traditional anastomosis. As local fluid dynamics could play a significant role in the onset of vessel wall pathologies, in this article a computational approach was designed to investigate flow patterns in the presence of the Ventrica magnetic vascular positioner (Ventrica MVP) device. A model of standard hand-sewn anastomosis and of automated magnetic anastomosis were constructed, and the finite volume method was used to simulate in silico realistic graft hemodynamics. Synthetic analytical descriptors -- i.e., time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and helical flow index (HFI) -- were calculated and compared for quantitative assessment of the anastomosis geometry hemodynamic performance. In this case study, the same most critical region was identified for the 2 models as the one with the lowest TAWSS and the highest OSI (TAWSS=0.229, OSI=0.255 for the hand-sewn anastomosis; TAWSS=0.297, OSI=0.171 for the Ventrica MVP(R)). However, the shape of the Ventrica MVP does not induce more critical wall shear stresses, oscillating flow and damped helicity in the graft fluid dynamics, as compared with conventional anastomosis. We found that the use of the Ventrica MVP for the case study under investigation was not associated with more critical fluid dynamics than with conventional hand-sewn anastomosis. Thereby, the device could facilitate beating heart and minimally invasive coronary artery bypass grafting without increasing local hemodynamic-related risks of failure.

Surgical anatomy and preservation of the middle meningeal artery during bypass surgery for moyamoya disease.

Science.gov (United States)

Hori, Satoshi; Kashiwazaki, Daina; Akioka, Naoki; Hayashi, Tomohide; Hori, Emiko; Umemura, Kimiko; Horie, Yukio; Kuroda, Satoshi

2015-01-01

The middle meningeal artery (MMA) is known to function as one of the important collateral routes in moyamoya disease. However, the anterior branch frequently courses within the lesser wing of the sphenoid bone and can easily be damaged during craniotomy for bypass surgery. This prospective study aimed to study the surgical anatomy of the MMA and to establish the technique to preserve it during bypass surgery for moyamoya disease. Twenty-two patients with moyamoya disease underwent STA-MCA anastomosis combined with indirect bypass on 27 sides. The anatomical relationship between the anterior branch of the MMA and lesser wing was classified into three types: the bridge, monorail, and tunnel types. During surgery, the lesser wing was carefully resected with a rongeur or high-speed diamond drill to preserve the anterior branch of the MMA. The anterior branch of the MMA was classified into the bridge type in 5 sides (18.5 %), monorail type in 10 sides (37.0 %), and tunnel type in 12 sides (44.5 %). Patient age was closely related to the anatomical findings (χ (2) test, p = 0.0168). Careful resection of the lesser wing with a rongeur could preserve bridge- and monorail-type MMAs (100 and 71.4 %, respectively). However, drilling out of the lesser wing under a surgical microscope was essential to preserve the tunnel-type MMA. Intraoperative indocyanine green videoangiography was useful to confirm patency during surgery. It is essential to understand the surgical anatomy of the MMA around the pterion in order to preserve its anterior branch during bypass surgery for moyamoya disease.

Continuous crossover femoropopliteal bypass in a 68-year-old gentleman with rest pain.

LENUS (Irish Health Repository)

Smith, F M

2012-02-03

Patients who have had multiple previous attempts at limb salvaging surgery frequently go on to have an amputation. This, however, results both in psychological perturbation for the patient and high rehabilitation costs for the community. Successful limb salvage surgery therefore has an important role in vascular surgery. We describe the management of a patient with critical limb ischemia that had previously undergone multiple limb salvage procedures and whose limb was saved by the use of a continuous femoropopliteal crossover bypass graft. The patient, who may have been deemed by some as a candidate for amputation, has full use of his limb 6 months after surgery with ankle brachial pressure index readings of 0.6. Continuous femoropopliteal crossover bypass grafting is a poorly described surgical technique that may be appropriate in a subgroup of patients and may allow salvage of a limb that otherwise may have been deemed fit for amputation.

Fatal air embolism during cardiopulmonary bypass : analysis of an incident and prevention measures

NARCIS (Netherlands)

van der Zee, Michiel P.; Koene, Bart M.; Mariani, Massimo A.

Air embolism is a life-threatening complication during cardiopulmonary bypass. We present a case of a patient who suffered an air embolism during coronary bypass surgery, despite standard safety features and procedures. The patient died 3 days after surgery due to massive cerebral oedema. This case

DIET MICRONUTRIENT ADEQUACY OF WOMEN AFTER 1 YEAR OF GASTRIC BYPASS

Science.gov (United States)

LEIRO, Larissa Silveira; Melendez-ARAÚJO, Mariana Silva

2014-01-01

Background The more effective treatment for severe obesity is bariatric surgery. Gastric bypass is a surgical technique used worldwide; however, as well as other techniques; it has postoperative risks, including nutrient deficiency. Aim To determine the amounts of dietary iron, calcium, vitamin D and vitamin B12 ingested by patients of a public hospital one year after gastric bypass, and compare with the recommendations of the Recommended Dietary Allowances. Methods This was a transverse descriptive study and the sample consisted of 36 women, with at least one year of gastric bypass. Data collected included sociodemographic, anthropometric and diet variables. Dietetic information was collected through a validated food frequency questionnaire. Ingestion of iron, calcium, vitamin D and vitamina B12 was evaluated in comparison with the Recommended Dietary Allowances, as well as correlation of micronutrient ingestion with time of surgery. Results There was inadequate consumption of iron, calcium and vitamin D. The vitamin B12 intake was considered adequate. There was statistically significant positive correlation between the time of surgery and the ingestion of iron, vitamin B12 and vitamin D. Conclusion The intake of iron, calcium and vitamin D of women one year after gastric bypass was inadequate, emphasizing the importance of multiprofessional monitoring postoperatively to prevent nutrient deficiencies. PMID:25409960

Effect of acetylcysteine on adaptation of intestinal smooth muscle after small bowel bypass

International Nuclear Information System (INIS)

Weisbrodt, N.W.; Belloso, R.M.; Biskin, L.C.; Dudrick, P.S.; Dudrick, S.J.

1986-01-01

The authors have postulated that the adaptive changes in function and structure of bypassed segments of small bowel are due in part to the change in intestinal contents following operation. The purpose of these experiments was to determine if a mucolytic agent could alter the adaptation. Rats were anesthetized and a 70% jejunoileal bypass was performed. The bypassed segments then were perfused with either saline or acetylcysteine for 3-12 days. Then, either intestinal transit was determined using Cr-51, or segments were taken for morphometric analysis. Transit, as assessed by the geometric center, was increased 32% by acetylcysteine treatment. Treatment also caused a decrease in hypertrophy of the muscularis. Muscle wet weight, muscle cross-sectional area, and muscle layer thickness all were significantly less in those animals infused with acetyl-cysteine. No decreases in hypertrophy were seen in the in-continuity segments. These data indicate that alterations in intestinal content can affect the course of adaptation of intestinal muscle in response to small bowel bypass

Utilising cardiopulmonary bypass for cancer surgery. Malignancy-induced protein C deficiency and thrombophilia.

LENUS (Irish Health Repository)

Marshall, C

2012-02-03

Cardiopulmonary bypass has evolved over the last 30 years. It is an important tool for the cardiac surgeon today and also has applications in non-cardiac operations such as surgery to extract tumours. Such patients undergoing surgery for cancer may be at an increased risk of a thromboembolic event post surgery, due to disturbances in the normal clotting pathway leading to hypercoagulability. One such disturbance is malignancy-induced Protein C deficiency. A deficiency of Protein C can cause hypercoagulabitity. Recent studies have examined cardiopulmonary bypass and inherited Protein C deficiency. However, surgery for cancer patients with a malignancy-induced Protein C deficiency involving cardiopulmonary bypass has not been reported. Surgery using CPB in these patients may result in increased morbidity and mortality. The objective of this article is to review the literature in order to discuss the occurrence, the aetiology and possible management of cancer patients with malignancy-induced Protein C deficiencies that require cardiopulmonary bypass for their surgery.

Microsurgical Bypass Training Rat Model: Part 2-Anastomosis Configurations.

Science.gov (United States)

Tayebi Meybodi, Ali; Lawton, Michael T; Yousef, Sonia; Mokhtari, Pooneh; Gandhi, Sirin; Benet, Arnau

2017-11-01

Mastery of microsurgical anastomosis is key to achieving good outcomes in cerebrovascular bypass procedures. Animal models (especially rodents) provide an optimal preclinical bypass training platform. However, the existing models for practicing different anastomosis configurations have several limitations. We sought to optimize the use of the rat's abdominal aorta and common iliac arteries (CIA) for practicing the 3 main anastomosis configurations commonly used in cerebrovascular surgery. Thirteen male Sprague-Dawley rats underwent inhalant anesthesia. The abdominal aorta and the CIAs were exposed. The distances between the major branches of the aorta were measured to find the optimal location for an end-to-end anastomosis. Also, the feasibility of performing side-to-side and end-to-side anastomoses between the CIAs was assessed. All bypass configurations could be performed between the left renal artery and the CIA bifurcation. The longest segments of the aorta without major branches were 1) between the left renal and left iliolumbar arteries (16.9 mm ± 4.6), and 2) between the right iliolumbar artery and the aortic bifurcation (9.7 mm ± 4.7). The CIAs could be juxtaposed for an average length of 7.6 mm ± 1.3, for a side-to-side anastomosis. The left CIA could be successfully reimplanted on to the right CIA at an average distance of 9.1 mm ± 1.6 from the aortic bifurcation. Our results show that rat's abdominal aorta and CIAs may be effectively used for all the anastomosis configurations used in cerebral revascularization procedures. We also provide technical nuances and anatomic descriptions to plan for practicing each bypass configuration. Copyright © 2017 Elsevier Inc. All rights reserved.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Jarbas Jakson Dinkhuysen

2014-09-01

Full Text Available Objective: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods: This study was performed in 52 patients (51% males, between 20 to 80 (67±14.4 years old weighing 53 to 102 (71.7±12.6 kg, mostly under myocardial revascularization surgery (34.6% and valvular surgery (32.8%. Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+, lactate desidrogenase (UI/L, fibrinogen level (mg/dL and platelet count (nº/mm3. Results: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application.

Does Off-Pump Coronary Artery Bypass Grafting Negatively Impact Long-Term Survival and Freedom from Reintervention?

Directory of Open Access Journals (Sweden)

Shahzad G. Raja

2013-01-01

Full Text Available Recently published evidence has raised concerns about worse late mortality and increasing need for reintervention after off-pump coronary artery bypass grafting. We undertook this study to assess the impact of off-pump coronary artery bypass grafting on survival and freedom from reintervention at 10 years. From January 2002 to December 2002, 307 consecutive patients who had isolated multivessel off-pump coronary artery bypass grafting at our institution were compared to a control group of 397 patients that underwent multivessel on-pump coronary artery bypass grafting during the same period. In addition, univariate and risk-adjusted comparisons between the two groups were performed at 10 years. Kaplan-Meier survival was similar for the two cohorts. After adjusting for clinical covariates, off-pump coronary artery bypass grafting did not emerge as a significant independent predictor of long-term mortality (Hazard Ratio 0.91; 95% Confidence Interval 0.70–1.12, readmission to hospital for cardiac cause (Hazard Ratio 0.96; 95% Confidence Interval 0.78–1.10, or the need for reintervention (Hazard Ratio 0.93; 95% Confidence Interval 0.87–1.05. Off-pump coronary artery bypass grafting compared with on-pump coronary artery bypass grafting does not adversely impact survival or freedom from reintervention at a 10-year follow-up.

Post-Gastric Bypass Hyperinsulinemic Hypoglycemia: Fructose is a Carbohydrate Which Can Be Safely Consumed.

Science.gov (United States)

Bantle, Anne E; Wang, Qi; Bantle, John P

2015-08-01

Postprandial hypoglycemia after gastric bypass surgery is a serious problem. Available treatments are often ineffective. The objective was to test the hypotheses that injection of rapid-acting insulin before a high-carbohydrate meal or replacement of other carbohydrates with fructose in the meal would prevent hypoglycemia. This was a randomized, crossover trial comparing a high-carbohydrate meal with premeal saline injection (control), a high-carbohydrate meal with premeal insulin injection, and a high-fructose meal with total carbohydrate content similar to the control meal. The setting was an academic medical center. Ten patients with post-gastric bypass hyperinsulinemic hypoglycemia participated. Interventions included lispro insulin injected before test meals and replacement of other carbohydrates with fructose in test meals. The main outcome measure was plasma glucose meals. After the control meal, mean peak glucose and insulin were 173 ± 47 mg/dL and 134 ± 55 mU/L, respectively; mean glucose nadir was 44 ± 15 mg/dL; and eight of 10 subjects demonstrated glucose meal, mean peak postprandial glucose and insulin were 117 ± 20 mg/dL and 45 ± 31 mU/L, respectively (both P meal sweetened with fructose with little risk of hypoglycemia. Treatment with rapid-acting insulin before a carbohydrate-containing meal did not prevent hypoglycemia.

Application of a pharmacokinetics-pharmacodynamics approach to the free propofol plasma levels during coronary artery bypass grafting surgery with hypothermic cardiopulmonary bypass

Directory of Open Access Journals (Sweden)

Carlos R. Silva-Filho

2018-02-01

Full Text Available OBJECTIVES: The objective of this study was to apply a pharmacokinetics-pharmacodynamics approach to investigate the free propofol plasma levels in patients undergoing coronary artery bypass grafting under hypothermic conditions compared with the off-pump procedure. METHODS: Nineteen patients scheduled for on-pump coronary artery bypass grafting under hypothermic conditions (n=10 or the equivalent off-pump surgery (n=9 were anesthetized with sufentanil and propofol target-controlled infusion (2 μg/mL during surgery. The propofol concentration was then reduced to 1 μg/mL, and a pharmacokinetics-pharmacodynamics analysis using the maximum-effect-sigmoid model obtained by plotting the bispectral index values against the free propofol plasma levels was performed. RESULTS: Significant increases (two- to five-fold in the free propofol plasma levels were observed in the patients subjected to coronary artery bypass grafting under hypothermic conditions. The pharmacokinetics of propofol varied according to the free drug levels in the hypothermic on-pump group versus the off-pump group. After hypothermic coronary artery bypass was initiated, the distribution volume increased, and the distribution half-life was prolonged. Propofol target-controlled infusion was discontinued when orotracheal extubation was indicated, and the time to patient extubation was significantly higher in the hypothermic on-pump group than in the off-pump group (459 versus 273 min, p=0.0048. CONCLUSIONS: The orotracheal intubation time was significantly longer in the hypothermic on-pump group than in the off-pump group. Additionally, residual hypnosis was identified through the pharmacokinetics-pharmacodynamics approach based on decreases in drug plasma protein binding in the hypothermic on-pump group, which could explain the increased hypnosis observed with this drug in this group of patients.

Study on flow regimes of high-pressure and dense-phase pneumatic conveying

International Nuclear Information System (INIS)

Lu Peng; Chen Xiaoping; Liang Cai; Pu Wenhao; Zhou Yun; Xu Pan; Zhao Changsui

2009-01-01

High-pressure and dense-phase pneumatic conveying of pulverized coal is a key technology in the field of large-scale entrained bed coal gasification. Flow regime plays an important role in two-phase flow because it affects not only flow behavior and safety operation, but also the reliability of practical processes. Few references and experiences in high-pressure and dense-phase conveying are available, especially for the flow regimes. And because of the high stickiness and electrostatic attraction of pulverized coal to the pipe wall, it is very difficult to make out the flow regimes in the conveying pipe by visualization method. Thus quartz powder was chosen as the conveyed material to study the flow regime. High-speed digital video camera was employed to photograph the flow patterns. Experiments were conducted on a pilot scale experimental setup at the pressure up to 3.6MPa. With the decrease in superficial gas velocity, three distinguishable flow regimes were observed: stratified flow, dune flow and plug flow. The characteristics of pressure traces acquired by high frequency response pressure transmitter and their EMD (Empirical Mode Decomposition) characteristics were correlated strongly with the flow regimes. Combining high-speed photography and pressure signal analysis together can make the recognition of flow patterns in the high-pressure and dense-phase pneumatic conveying system more accurate. The present work will lead to better understanding of the flow regime transition under high-pressure.

Role of ternary fission in synthesis of bypassed nuclei