scholarly journals Boundary conditions investigation to improve computer simulation of cerebrospinal fluid dynamics in hydrocephalus patients

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Seifollah Gholampour ◽  
Nasser Fatouraee
Keyword(s):  
Cerebrospinal Fluid ◽  
Boundary Conditions ◽  
Fluid Dynamic ◽  
Ventricular System ◽  
Volume Changes ◽  
Csf Pressure ◽  
Cfd Method ◽  
Cine Phase Contrast ◽  
Fully Coupled ◽  
System Volume

AbstractThree-D head geometrical models of eight healthy subjects and 11 hydrocephalus patients were built using their CINE phase-contrast MRI data and used for computer simulations under three different inlet/outlet boundary conditions (BCs). The maximum cerebrospinal fluid (CSF) pressure and the ventricular system volume were more effective and accurate than the other parameters in evaluating the patients’ conditions. In constant CSF pressure, the computational patient models were 18.5% more sensitive to CSF volume changes in the ventricular system under BC “C”. Pulsatile CSF flow rate diagrams were used for inlet and outlet BCs of BC “C”. BC “C” was suggested to evaluate the intracranial compliance of the hydrocephalus patients. The results suggested using the computational fluid dynamic (CFD) method and the fully coupled fluid-structure interaction (FSI) method for the CSF dynamic analysis in patients with external and internal hydrocephalus, respectively.

Cerebrospinal Fluid Hydromechanics in Adult Patients with Benign Noncommunicating Hydrocephalus: One-Hour Test Shunting and Balanced Cerebrospinal Fluid Infusion test to Select Patients for Intracranial Bypass Operation

Neurosurgery ◽  
1982 ◽  
Vol 11 (6) ◽  
pp. 769-775 ◽  
Author(s):  
Bjørn Magnæs
Keyword(s):  
Cerebrospinal Fluid ◽  
Ventricular System ◽  
Bypass Operation ◽  
Infusion Test ◽  
Fluid Infusion ◽  
Csf Pressure ◽  
Constant Rate ◽  
Noncommunicating Hydrocephalus ◽  
Csf Absorption

Abstract Cerebrospinal fluid (CSF) pressure and absorption were determined in 12 patients with benign noncommunicating hydrocephalus. An extracorporeal communication of plastic tubing between the ventricular system and the lumbar subarachnoid space was established to imitate the hydromechanical condition after an intracranial bypass operation. This extracorporeal shunt, which in effect was an externalized Torkildsen shunt, served first as a test shunt for 1 hour and then as a route for the constant rate CSF infusion test. The total CSF absorptive capacity was thus determined under a condition of balanced CSF pressure between the proximal and distal compartment. Four patients, whose tests showed normal CSF pressure and absorption, were selected for intracranial bypass operation. Follow-up examination showed a normal clinical condition, reduction of the ventricular system, normal CSF pressure, and normal CSF absorption in all 4 patients. The other 8 patients, whose tests indicated impaired CSF absorption, were treated by ventriculoatrial shunting. The tests were valid in selecting patients for intracranial bypass operation.

Venous and CSF pressure in cerebral infarction with a hemorrhagic component

1985 ◽  
Vol 66 (6) ◽  
pp. 419-421
Author(s):  
A. A. Ashman
Keyword(s):  
Cerebrospinal Fluid ◽  
Ischemic Stroke ◽  
Cerebral Infarction ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Csf Pressure

Literature data on the value of cerebrospinal fluid pressure in certain forms of ischemic stroke are few and contradictory.

Digital manometry to measure cerebrospinal fluid pressure during lumbar puncture

2021 ◽  
pp. 197140092110551
Author(s):  
Robert Heider ◽  
Peter G Kranz ◽  
Erin Hope Weant ◽  
Linda Gray ◽  
Timothy J Amrhein
Keyword(s):  
Cerebrospinal Fluid ◽  
Lumbar Puncture ◽  
Pressure Measurement ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Pressure Measurements ◽  
Csf Pressure ◽  
Left Lateral Decubitus Position ◽  
Significant Difference ◽  
Time Savings

Rationale and Objectives Accurate cerebrospinal fluid (CSF) pressure measurements are critical for diagnosis and treatment of pathologic processes involving the central nervous system. Measuring opening CSF pressure using an analog device takes several minutes, which can be burdensome in a busy practice. The purpose of this study was to compare accuracy of a digital pressure measurement device with analog manometry, the reference gold standard. Secondary purpose included an assessment of possible time savings. Materials and Methods This study was a retrospective, cross-sectional investigation of 71 patients who underwent image-guided lumbar puncture (LP) with opening CSF pressure measurement at a single institution from June 2019 to September 2019. Exclusion criteria were examinations without complete data for both the digital and analog measurements or without recorded needle gauge. All included LPs and CSF pressures were measured with the patient in the left lateral decubitus position, legs extended. Acquired data included (1) digital and analog CSF pressures and (2) time required to measure CSF pressure. Results A total of 56 procedures were analyzed in 55 patients. There was no significant difference in mean CSF pressures between devices: 22.5 cm H2O digitally vs 23.1 analog ( p = .7). Use of the digital manometer resulted in a time savings of 6 min (438 s analog vs 78 s digital, p < .001). Conclusion Cerebrospinal fluid pressure measurements obtained with digital manometry demonstrate comparable accuracy to the reference standard of analog manometry, with an average time savings of approximately 6 min per case.

Lumbar Cerebrospinal Fluid Opening Pressure Measured in a Flexed Lateral Decubitus Position in Children

PEDIATRICS ◽  
1994 ◽  
Vol 93 (4) ◽  
pp. 622-623
Author(s):  
Robert Ellis
Keyword(s):  
Cerebrospinal Fluid ◽  
Intrathecal Chemotherapy ◽  
Lateral Decubitus Position ◽  
Normal Range ◽  
Opening Pressure ◽  
Csf Pressure ◽  
Normal Ranges ◽  
Extended Position ◽  
Lateral Decubitus ◽  
Lumbar Cerebrospinal Fluid

Objective. Lumbar punctures in children are generally performed in a flexed position. Published normal ranges for cerebrospinal fluid (CSF) opening pressure require measurement in an extended position, and flexion is known to increase lumbar CSF pressure. This study sought to determine a normal range (mean ± 2 SD) for lumbar CSF opening pressure measured in a flexed lateral decubitus position in children. Methods. Opening pressure was measured in 33 children receiving diagnostic lumbar punctures or prophylactic intrathecal chemotherapy. Measurements were performed in a flexed lateral decubitus position. Patients with medical conditions affecting CSF pressure were excluded. Results. Opening pressure (mean ± SD) was 19.0 ± 4.4 cm H2O. Opening pressure was not significantly affected by patient age or sex. Intrathecal chemotherapy and sedation also did not affect CSF pressure. Conclusions. The normal range for lumbar CSF opening pressure measured in a flexed lateral decubitus position in children is 10 to 28 cm H2O.

scholarly journals Pliocene Model Intercomparison Project (PlioMIP): experimental design and boundary conditions (Experiment 2)

2011 ◽  
Vol 4 (3) ◽  
pp. 571-577 ◽  
Author(s):  
A. M. Haywood ◽  
H. J. Dowsett ◽  
M. M. Robinson ◽  
D. K. Stoll ◽  
A. M. Dolan ◽  
...  
Keyword(s):  
Experimental Design ◽  
Boundary Conditions ◽  
Initial Phase ◽  
Climate Models ◽  
Model Development ◽  
Warm Period ◽  
Model Intercomparison ◽  
Ocean Atmosphere ◽  
Intercomparison Project ◽  
Fully Coupled

Abstract. The Palaeoclimate Modelling Intercomparison Project has expanded to include a model intercomparison for the mid-Pliocene warm period (3.29 to 2.97 million yr ago). This project is referred to as PlioMIP (the Pliocene Model Intercomparison Project). Two experiments have been agreed upon and together compose the initial phase of PlioMIP. The first (Experiment 1) is being performed with atmosphere-only climate models. The second (Experiment 2) utilises fully coupled ocean-atmosphere climate models. Following on from the publication of the experimental design and boundary conditions for Experiment 1 in Geoscientific Model Development, this paper provides the necessary description of differences and/or additions to the experimental design for Experiment 2.

scholarly journals Multi-Fidelity Simulation of a Turbofan Engine With Results Zoomed Into Mini-Maps for a Zero-D Cycle Simulation

2004 ◽  
Author(s):  
Mark G. Turner ◽  
John A. Reed ◽  
Robert Ryder ◽  
Joseph P. Veres
Keyword(s):  
Boundary Conditions ◽  
Fluid Dynamic ◽  
Thermodynamic Cycle ◽  
High Fidelity ◽  
Operating Characteristics ◽  
Cycle Model ◽  
Turbofan Engine ◽  
Engine Model ◽  
Cycle Simulation ◽  
Component Models

A Zero-D cycle simulation of the GE90-94B high bypass turbofan engine has been achieved utilizing mini-maps generated from a high-fidelity simulation. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled 3D computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady-state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the 3D component models are integrated into the cycle model via partial performance maps generated from the CFD flow solutions using one-dimensional meanline turbomachinery programs. This paper high-lights the generation of the highpressure compressor, booster, and fan partial performance maps, as well as turbine maps for the high pressure and low pressure turbine. These are actually “mini-maps” in the sense that they are developed only for a narrow operating range of the component. Results are compared between actual cycle data at a take-off condition and the comparable condition utilizing these mini-maps. The mini-maps are also presented with comparison to actual component data where possible.

scholarly journals The Design and Implementation of Fan Chips as Cooling for Milling Process on Aluminum Alloy 5086 to Increase Tool Life

2021 ◽  
Vol 2 (1) ◽  
pp. 29-42
Author(s):  
Agus Sifa ◽  
Dedi Suwandi ◽  
Tito Endramawan ◽  
Alam Aulia Rachman
Keyword(s):  
Aluminum Alloy ◽  
Tool Life ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
Milling Process ◽  
Machining Process ◽  
Central Character ◽  
Spindle Rotation ◽  
Cfd Method ◽  
Increase Tool Life

In the metal machining process, especially in the milling process, the parameters that affect the quality milling process results are cooling media because it affects the tool life used. This paper aims to determine the performance of using fan chips as the coolant in the dry milling process area. The method used is the computational fluid dynamic (CFD) method and the experimental milling process on a workpiece made from aluminum alloy 5086. In experimental testing using a variation of the milling machine spindle rotation. The simulation test results on the fluid flow character on fan chips with a protector producing a central character with a small area. In contrast, fan chips without a protector make a central character with a broader area. The wind speed data in simulation testing and experimental testing produced the same trend graph. The results of the performance of fan chips after experimented with variations in spindle rotation, cooling process on area occurs when the motor spindle rotates above 1120 Rpm on the fan chips with a protector, and the engine spindle rotates above 770 Rpm on the fan chips without a protector. The effect of fan chips on tool life affects increasing tool life by 8 minutes on installing fan chips with a protector and increasing tool life by 12 minutes on installing fan chips without a protector.

Apparatus for long-term ventricular access in the awake canine

1986 ◽  
Vol 61 (1) ◽  
pp. 368-372 ◽  
Author(s):  
E. C. Ellison ◽  
T. T. Pappas ◽  
W. G. Pace ◽  
T. M. O'Dorisio
Keyword(s):  
Molecular Weight ◽  
Central Nervous System ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Peripheral Blood ◽  
Ventricular System ◽  
Blood Levels ◽  
Maximum Frequency ◽  
Fatal Complications

An apparatus is described that permits lateral ventricular cerebrospinal fluid (CSF) to be sampled or an infusion to be performed into the ventricular system in the awake canine. The device has been used in 25 dogs. CSF was sampled, and experiments involving infusions into the lateral ventricle were performed over a 6- to 24-mo period. The maximum frequency of ventricular cannulation using the apparatus was once per week. Complications occurred in 10 dogs, all of which were successfully treated, permitting experiments to continue. Three fatal complications included meningitis in one animal at 24 mo and seizures in two animals, causing death at 12 and 18 mo. Administration of peptides, bombesin, and somatostatin into the ventricular system was followed by prompt rises in bombesin and somatostatin radioimmunoactivity in the CSF. There were no parallel increases of these peptides in the peripheral blood levels up to 2 h after infusion. Peptides of this molecular weight infused with this apparatus do not seem to leak into peripheral blood. The apparatus permits repeated ventricular cannulation in the awake canine for sampling of CSF and administration of biological substances to determine specific central nervous system action.

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