Mechanisms of fluid production in smooth adhesive pads of insects

PubMed Central

Dirks, Jan-Henning; Federle, Walter

2011-01-01

Insect adhesion is mediated by thin fluid films secreted into the contact zone. As the amount of fluid affects adhesive forces, a control of secretion appears probable. Here, we quantify for the first time the rate of fluid secretion in adhesive pads of cockroaches and stick insects. The volume of footprints deposited during consecutive press-downs decreased exponentially and approached a non-zero steady state, demonstrating the presence of a storage volume. We estimated its size and the influx rate into it from a simple compartmental model. Influx was independent of step frequency. Fluid-depleted pads recovered maximal footprint volumes within 15 min. Pads in stationary contact accumulated fluid along the perimeter of the contact zone. The initial fluid build-up slowed down, suggesting that flow is driven by negative Laplace pressure. Freely climbing stick insects left hardly any traceable footprints, suggesting that they save secretion by minimizing contact area or by recovering fluid during detachment. However, even the highest fluid production rates observed incur only small biosynthesis costs, representing less than 1 per cent of the resting metabolic rate. Our results show that fluid secretion in insect wet adhesive systems relies on simple physical principles, allowing for passive control of fluid volume within the contact zone. PMID:21208970

Goal-directed fluid optimization based on stroke volume variation and cardiac index during one-lung ventilation in patients undergoing thoracoscopy lobectomy operations: a pilot study.

PubMed

Zhang, Jian; Chen, Chao Qin; Lei, Xiu Zhen; Feng, Zhi Ying; Zhu, Sheng Mei

2013-07-01

This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation.

Computer simulation of preflight blood volume reduction as a countermeasure to fluid shifts in space flight

NASA Technical Reports Server (NTRS)

Simanonok, K. E.; Srinivasan, R.; Charles, J. B.

1992-01-01

Fluid shifts in weightlessness may cause a central volume expansion, activating reflexes to reduce the blood volume. Computer simulation was used to test the hypothesis that preadaptation of the blood volume prior to exposure to weightlessness could counteract the central volume expansion due to fluid shifts and thereby attenuate the circulatory and renal responses resulting in large losses of fluid from body water compartments. The Guyton Model of Fluid, Electrolyte, and Circulatory Regulation was modified to simulate the six degree head down tilt that is frequently use as an experimental analog of weightlessness in bedrest studies. Simulation results show that preadaptation of the blood volume by a procedure resembling a blood donation immediately before head down bedrest is beneficial in damping the physiologic responses to fluid shifts and reducing body fluid losses. After ten hours of head down tilt, blood volume after preadaptation is higher than control for 20 to 30 days of bedrest. Preadaptation also produces potentially beneficial higher extracellular volume and total body water for 20 to 30 days of bedrest.

Bed-rest studies: Fluid and electrolyte responses

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.

1983-01-01

Confinement in the horizontal position for 2 to 3 weeks results in a chronic decrease in plasma volume, increased interstitial fluid volume, and unchanged or slightly increased extracellular fluid volume. Concentrations of blood electrolytes, glucose, and nitrogenous constituents remain within normal limits of variability when maintenance levels of isometric or isotonic exercise are performed for 1 hr/day. Hematocrit and plasma osmolality can be elevated significantly throughout bed rest (BR). Significant diuresis occurs on the first day, and increases in urine Na and Ca continue throughout BR, although voluntary fluid intake is unchanged. Urine Na and K are evaluated during the second week of BR in spite of stabilization of PV and extracellular volume. The initial diuresis probably arises from the extracellular fluid while subsequent urine loss above control levels must come from the intracellular fluid. Preservation of the extracellular volume takes precedance over maintenance of the intracellular fluid volume. The functioning of a natriuretic factor (hormone) to account for the continued increased loss of Na in the urine is suggested.

The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis.

PubMed

Ouanes, Jean-Pierre P; Bicket, Mark C; Togioka, Brandon; Tomas, Vicente Garcia; Wu, Christopher L; Murphy, Jamie D

2015-03-01

To determine if preoperative gum chewing affects gastric pH and gastric fluid volume. Systematic review and meta-analysis. Data sources included Cochrane, PubMed, and EMBASE databases from inception to June 2012 and reference lists of known relevant articles without language restriction. Randomized controlled trials in which a treatment group that chewed gum was compared to a control group that fasted were included. Relevant data, including main outcomes of gastric fluid volume and gastric pH, were extracted. Four studies involving 287 patients were included. The presence of chewing gum was associated with small but statically significant increases in gastric fluid volume (mean difference = 0.21 mL/kg; 95% confidence interval, 0.02-0.39; P = .03) but not in gastric pH (mean difference = 0.11 mL/kg; 95% confidence interval, -0.14 to 0.36; P = .38). Gastric fluid volume and gastric pH remained unchanged in subgroup analysis by either sugar or sugarless gum type. Chewing gum in the perioperative period causes small but statically significant increases in gastric fluid volume and no change in gastric pH. The increase in gastric fluid most likely is of no clinical significance in terms of aspiration risk for the patient. Elective surgery should not necessarily be canceled or delayed in healthy patients who accidentally chew gum preoperatively. Copyright © 2014 Elsevier Inc. All rights reserved.

[Development and evaluation of individualized fluid therapy in the elderly patients with coronary heart disease undergoing gastrointestinal surgery: a randomized, controlled trial].

PubMed

Zheng, Hong; Guo, Hai; Ye, Jian-rong; Chen, Lin

2012-06-01

To develop and evaluate an individualized fluid therapy in the elderly patients with coronary heart disease undergoing gastrointestinal surgery. In this prospective study, 60 coronary heart disease patients undergoing gastrointestinal surgery were included in the First Affiliated Hospital of Xinjiang Medical University from March 2009 to March 2012. Patients were randomized into the intervention group and the control group with 30 patients in each group. Individualized fluid therapy was used during surgery and postoperative period in the ICU, which was determined based on target controlled fluid therapy according to cardiac index, stroke volume, and stroke volume variation. Traditional fluid therapy was used in the control group in the intraoperative and postoperative period. The two groups were compared in terms of postoperative hemodynamic parameters, total fluid volume, incidence of adverse cardiac events, and recovery of bowel function. Compared with the control group, mean arterial pressure was significantly increased at the commencement of the surgery. The cardiac index was significantly elevated during surgery and at the end of the surgery. Stroke volume was significantly increased after induction of anesthesia, during the surgery, and at the early stay of ICU period(all P<0.05). Serum lactic acid in the intervention group was significantly lower at the end of surgery and during ICU stay than that in the control group (all P<0.05). During surgery and 24-hour stay in ICU, the total fluid volume, crystal usage, and urine were significantly less, while colloidal fluid use was significantly more in the intervention group as compared to the control group(all P<0.05). The perioperative adverse cardiac event rate was 36.7%(11/30) in the intervention group, lower than 56.7%(17/30) in the control group, but the difference was no statistically significance(P>0.05). In the intervention group, defecation time, time to first flatus, resumption of liquid intake, length of ICU stay and hospital stay were significantly less compared with the control group(P<0.05). In the elderly patients with coronary arterial disease undergoing gastrointestinal surgery, individualized fluid therapy can effectively decrease adverse cardiac events, improve postoperative gastrointestinal function, and reduce length of hospital stay.

Fluid compartment and renal function alterations in the rat during 7 and 14 day head down tilt

NASA Technical Reports Server (NTRS)

Tucker, Bryan J.

1991-01-01

Exposure to conditions of microgravity for any extended duration can modify the distribution of fluid within the vascular and interstitial spaces, and eventually intracellular volume. Whether the redistribution of fluid and resetting of volume homeostasis mechanisms is appropriate for the long term environmental requirements of the body in microgravity remains to be fully defined. The event that initiates the change in fluid volume homeostasis is the cephalad movement of fluid which potentially triggers volume sensors and stretch receptors (atrial stretch with the resulting release of atrial natriuretic peptide) and suppresses adrenergic activity via the carotid and aortic arch baroreceptors. All these events act in concert to reset blood and interstitial volume to new levels, which in turn modify the renin-angiotensin system. All these factors have an influence on the kidney, the end organ for fluid volume control. How the fluid compartment volume changes interrelate with alterations in renal functions under conditions of simulated microgravity is the focus of the present investigation which utilizes 25-30 deg head-down tilt in the rat.

Bed-rest studies - Fluid and electrolyte responses

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.

1983-01-01

Confinement in the horizontal position for 2 to 3 weeks results in a chronic decrease in plasma volume, increased interstitial fluid volume, and unchanged or slightly increased extracellular fluid volume. Concentrations of blood electrolytes, glucose, and nitrogenous constituents remain within normal limits of variability when maintenance levels of isometric or isotonic exercise are performed for 1 hr/day. Hematocrit and plasma osmolality can be elevated significantly throughout bed rest (BR). Significant diuresis occurs on the first day, and increases in urine Na and Ca continue throughout BR, although voluntary fluid intake is unchanged. Urine Na and K are evaluated during the second week of BR in spite of stabilization of PV and extracellular volume. The initial diuresis probably arises from extracellular fluid while subsequent urine loss above control levels must come from the intracellular fluid. Preservation of the extracellular volume takes precedance over maintenance of the intracellular fluid volume. The functioning of a natriuretic factor (hormone) to account for the continued increased loss of Na in the urine is suggested. Previously announced in STAR as N83-24160

A Second Law Based Unstructured Finite Volume Procedure for Generalized Flow Simulation

NASA Technical Reports Server (NTRS)

Majumdar, Alok

1998-01-01

An unstructured finite volume procedure has been developed for steady and transient thermo-fluid dynamic analysis of fluid systems and components. The procedure is applicable for a flow network consisting of pipes and various fittings where flow is assumed to be one dimensional. It can also be used to simulate flow in a component by modeling a multi-dimensional flow using the same numerical scheme. The flow domain is discretized into a number of interconnected control volumes located arbitrarily in space. The conservation equations for each control volume account for the transport of mass, momentum and entropy from the neighboring control volumes. In addition, they also include the sources of each conserved variable and time dependent terms. The source term of entropy equation contains entropy generation due to heat transfer and fluid friction. Thermodynamic properties are computed from the equation of state of a real fluid. The system of equations is solved by a hybrid numerical method which is a combination of simultaneous Newton-Raphson and successive substitution schemes. The paper also describes the application and verification of the procedure by comparing its predictions with the analytical and numerical solution of several benchmark problems.

Orthostatic stress is necessary to maintain the dynamic range of cardiovascular control in space

NASA Technical Reports Server (NTRS)

Baisch, J. F.; Wolfram, G.; Beck, L.; Drummer, C.; Stormer, I.; Buckey, J.; Blomqvist, G.

2000-01-01

In the upright position, gravity fills the low-pressure systems of human circulation with blood and interstitial fluid in the sections below the diaphragm. Without gravity one pressure component in the vessels disappears and the relationship between hydrostatic pressure and oncotic pressure, which regulates fluid passage across the capillary endothelium in the terminal vascular bed, shifts constantly. The visible consequences of this are a puffy face and "bird" legs. The plasma volume shrinks in space and the range of cardiovascular control is reduced. When they stand up for the first time after landing, 30-50% of astronauts suffer from orthostatic intolerance. It remains unclear whether microgravity impairs cardiovascular reflexes, or whether it is the altered volume status that causes the cardiovascular instability following space flight. Lower body negative pressure was used in several space missions to stimulate the cardiovascular reflexes before, during and after a space flight. The results show that cardiovascular reflexes are maintained in microgravity. However, the astronauts' volume status changed in space, towards a volume-retracted state, as measurements of fluid-regulating hormones have shown. It can be hypothesized that the control of circulation and body fluid homeostasis in humans is adapted to their upright posture in the Earth's gravitational field. Autonomic control regulates fluid distribution to maintain the blood pressure in that posture, which most of us have to cope with for two-thirds of the day. A determined amount of interstitial volume is necessary to maintain the dynamic range of cardiovascular control in the upright posture; otherwise orthostatic intolerance may occur more often.

Overnight fluid shifts in subjects with and without obstructive sleep apnea

PubMed Central

Ding, Ning; Lin, Wei; Zhang, Xi-Long; Ding, Wen-Xiao; Gu, Bing; Ni, Bu-Qing; Zhang, Wei; Zhang, Shi-Jiang

2014-01-01

Objective To investigate the characteristics of baseline body fluid content and overnight fluid shifts between non-obstructive sleep apnea (non-OSA) and obstructive sleep apnea (OSA) subjects. Methods A case-controlled study was performed between February 2013 and January 2014, with 36 (18 OSA and 18 non-OSA) outpatients enrolled in this study. Polysomnographic parameters and results of body fluid were compared between the two groups. Results There were no differences in age, weight, and body mass index (BMI) between groups. Compared with the non-OSA group, OSA group had significantly higher neck circumference (NC) and fluid volume shift in the legs. OSA patients had higher left and right leg fluid indices than non-OSA subjects. There were significant correlations between apnoea-hypopnoea index and baseline fluid indices in both legs as well as the reduction in overnight change in both legs fluid volume. The increase in NC was also significantly correlated with the reduction in overnight change in both legs fluid volume, but not with the change in head and neck fluid volume. There were significant correlations between change in NC and increased fluid shifts in head and neck volume. Conclusions OSA patients had a higher baseline fluid content in both legs as compared with non-OSA subjects, which may be the basic factor with regards to fluid shifts in OSA patients. The increase in head and neck fluid shift volume did not directly correlate with the severity of OSA. PMID:25589967

Effects of 30 day simulated microgravity and recovery on fluid homeostasis and renal function in the rat

NASA Technical Reports Server (NTRS)

Tucker, Bryan J.; Mendonca, Margarida M.

1995-01-01

Transition from a normal gravitational environment to that of microgravity eventually results in decreased plasma and blood volumes, increasing with duration of exposure to microgravity. This loss of vascular fluid is presumably due to negative fluid and electrolyte balance and most likely contributes to the orthostatic intolerance associated with the return to gravity. The decrease in plasma volume is presumed to be a reflection of a concurrent decrease in extracellular fluid volume with maintenance of normal plasma-interstitial fluid balance. In addition, the specific alterations in renal function contributing to these changes in fluid and electrolyte homeostasis are potentially responding to neuro-humoral signals that are not consistent with systemic fluid volume status. We have previously demonstrated an early increase in both glomerular filtration rate and extracellular fluid volume and that this decreases towards control values by 7 days of simulated microgravity. However, longer duration studies relating these changes to plasma volume alterations and the response to return to orthostasis have not been fully addressed. Male Wistar rats were chronically cannulated, submitted to 30 days heat-down tilt (HDT) and followed for 7 days after return to orthostasis from HDT. Measurements of renal function and extracellular and blood volumes were performed in the awake rat.

Control volume based hydrocephalus research; analysis of human data

NASA Astrophysics Data System (ADS)

Cohen, Benjamin; Wei, Timothy; Voorhees, Abram; Madsen, Joseph; Anor, Tomer

2010-11-01

Hydrocephalus is a neuropathophysiological disorder primarily diagnosed by increased cerebrospinal fluid volume and pressure within the brain. To date, utilization of clinical measurements have been limited to understanding of the relative amplitude and timing of flow, volume and pressure waveforms; qualitative approaches without a clear framework for meaningful quantitative comparison. Pressure volume models and electric circuit analogs enforce volume conservation principles in terms of pressure. Control volume analysis, through the integral mass and momentum conservation equations, ensures that pressure and volume are accounted for using first principles fluid physics. This approach is able to directly incorporate the diverse measurements obtained by clinicians into a simple, direct and robust mechanics based framework. Clinical data obtained for analysis are discussed along with data processing techniques used to extract terms in the conservation equation. Control volume analysis provides a non-invasive, physics-based approach to extracting pressure information from magnetic resonance velocity data that cannot be measured directly by pressure instrumentation.

30 CFR 250.514 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... equivalent well-control fluid volume shall be calculated and posted near the operator's station. A mechanical... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Well-control fluids, equipment, and operations... OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Completion...

Fluid control structures in microfluidic devices

DOEpatents

Mathies, Richard A.; Grover, William H.; Skelley, Alison; Lagally, Eric; Liu, Chung N.

2008-11-04

Methods and apparatus for implementing microfluidic analysis devices are provided. A monolithic elastomer membrane associated with an integrated pneumatic manifold allows the placement and actuation of a variety of fluid control structures, such as structures for pumping, isolating, mixing, routing, merging, splitting, preparing, and storing volumes of fluid. The fluid control structures can be used to implement a variety of sample introduction, preparation, processing, and storage techniques.

Fluid control structures in microfluidic devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathies, Richard A.; Grover, William H.; Skelley, Alison

2017-05-09

Methods and apparatus for implementing microfluidic analysis devices are provided. A monolithic elastomer membrane associated with an integrated pneumatic manifold allows the placement and actuation of a variety of fluid control structures, such as structures for pumping, isolating, mixing, routing, merging, splitting, preparing, and storing volumes of fluid. The fluid control structures can be used to implement a variety of sample introduction, preparation, processing, and storage techniques.

Fluid control structures in microfluidic devices

NASA Technical Reports Server (NTRS)

Skelley, Alison (Inventor); Mathies, Richard A. (Inventor); Lagally, Eric (Inventor); Grover, William H. (Inventor); Liu, Chung N. (Inventor)

2008-01-01

Methods and apparatus for implementing microfluidic analysis devices are provided. A monolithic elastomer membrane associated with an integrated pneumatic manifold allows the placement and actuation of a variety of fluid control structures, such as structures for pumping, isolating, mixing, routing, merging, splitting, preparing, and storing volumes of fluid. The fluid control structures can be used to implement a variety of sample introduction, preparation, processing, and storage techniques.

Fluidic Oscillator Having Decoupled Frequency and Amplitude Control

NASA Technical Reports Server (NTRS)

Koklu, Mehti (Inventor)

2017-01-01

A fluidic oscillator having independent frequency and amplitude control includes a fluidic-oscillator main flow channel having a main flow inlet, a main flow outlet, and first and second control ports disposed at opposing sides thereof. A fluidic-oscillator controller has an inlet and outlet. A volume defined by the main flow channel is greater than the volume defined by the controller. A flow diverter coupled to the outlet of the controller defines a first fluid flow path from the controller's outlet to the first control port and defines a second fluid flow path from the controller's outlet to the second control port.

Fluidic Oscillator Having Decoupled Frequency and Amplitude Control

NASA Technical Reports Server (NTRS)

Koklu, Mehti (Inventor)

2016-01-01

A fluidic oscillator having independent frequency and amplitude control includes a fluidic-oscillator main flow channel having a main flow inlet, a main flow outlet, and first and second control ports disposed at opposing sides thereof. A fluidic-oscillator controller has an inlet and outlet. A volume defined by the main flow channel is greater than the volume defined by the controller. A flow diverter coupled to the outlet of the controller defines a first fluid flow path from the controller's outlet to the first control port and defines a second fluid flow path from the controller's outlet to the second control port.

Cardiovascular and fluid volume control in humans in space.

PubMed

Norsk, Peter

2005-08-01

The human cardiovascular system and regulation of fluid volume are heavily influenced by gravity. When decreasing the effects of gravity in humans such as by anti-orthostatic posture changes or immersion into water, venous return is increased by some 25%. This leads to central blood volume expansion, which is accompanied by an increase in renal excretion rates of water and sodium. The mechanisms for the changes in renal excretory rates include a complex interaction of cardiovascular reflexes, neuroendocrine variables, and physical factors. Weightlessness is unique to obtain more information on this complex interaction, because it is the only way to completely abolish the effects of gravity over longer periods. Results from space have been unexpected, because astronauts exhibit a fluid and sodium retaining state with activation of the sympathetic nervous system, which subjects during simulations by head-down bed rest do not. Therefore, the concept as to how weightlessness affects the cardiovascular system and modulates regulation of body fluids should be revised and new simulation models developed. Knowledge as to how gravity and weightlessness modulate integrated fluid volume control is of importance for understanding pathophysiology of heart failure, where gravity plays a strong role in fluid and sodium retention.

Comparison of esophageal Doppler and plethysmographic variability index to guide intraoperative fluid therapy for low-risk patients undergoing colorectal surgery.

PubMed

Warnakulasuriya, Samantha R; Davies, Simon J; Wilson, R Jonathan T; Yates, David R A

2016-11-01

This study aims to investigate if there is equivalence in volumes of fluid administered when intravenous fluid therapy is guided by Pleth Variability Index (PVI) compared to the established technology of esophageal Doppler in low-risk patients undergoing major colorectal surgery. Randomized controlled trial. Operating room. Forty low-risk patients undergoing elective colorectal surgery. Patients were monitored by esophageal Doppler and PVI probes and were randomized to have fluid therapy directed by using one of these technologies, with 250 mL boluses of colloid to maintain a maximal stroke volume, or a PVI of less than 14%. Absolute volumes of fluid volumes given intraoperatively were measured as were 24 hours fluid volumes. Perioperative measurements of lactate and base excess were recorded as were postoperative complications. There was no significant difference between PVI and esophageal Doppler groups in mean total fluid administered (1286 vs 1520 mL, P=.300) or mean intraoperative fluid balance (+839 v+1145 mL, P=.150). PVI offers an entirely non-invasive alternative for goal-directed fluid therapy in this group of patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Whole-body fluid distribution in humans during dehydration and recovery, before and after humid-heat acclimation induced using controlled hyperthermia.

PubMed

Patterson, M J; Stocks, J M; Taylor, N A S

2014-04-01

This experiment was designed to test the hypothesis that the plasma volume is not selectively defended during exercise- and heat-induced dehydration following humid-heat acclimation. Eight physically active males were heat acclimated (39.8 °C, relative humidity 59.2%) using 17 days of controlled hyperthermia (core temperature: 38.5 °C). Inter-compartmental fluid losses and movements were tracked (radioisotopes and Evans blue dye) during progressive dehydration (cycling) in these same conditions and also during a resting recovery without fluid replacement (28 °C), before (day 1), during (day 8) and after heat acclimation (day 22). On days 8 and 22, there were significant increases in total body water, interstitial fluid and plasma volume (P < 0.05), but the intracellular compartments did not change (P > 0.05). The baseline plasma volume remained expanded throughout: 43.4 [±2.6 (day 1)], 49.1 [±2.4 (day 8); P < 0.05] and 48.9 mL kg(-1) [±3.0 (day 22); P < 0.05]. During progressive dehydration, plasma reductions of 9.0% (±0.9: day 1), 12.4% (±1.6: day 8) and 13.6% (±1.2: day 22) were observed, with day 8 and 22 losses significantly exceeding day 1 (P < 0.05). During recovery, plasma volume restoration commenced, with the intracellular fluid contribution becoming more pronounced as acclimation progressed. It is concluded that the plasma volume was not defended more vigorously following humid-heat acclimation. Indeed, a greater fluid loss may well underlie the mechanisms for enhancing plasma volume recovery when heat acclimation is induced using the controlled-hyperthermia technique. © 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Low current plasmatron fuel converter having enlarged volume discharges

DOEpatents

Rabinovich, Alexander; Alexeev, Nikolai; Bromberg, Leslie; Cohn, Daniel R.; Samokhin, Andrei

2005-04-19

A novel apparatus and method is disclosed for a plasmatron fuel converter (""plasmatron"") that efficiently uses electrical energy to produce hydrogen rich gas. The volume and shape of the plasma discharge is controlled by a fluid flow established in a plasma discharge volume. A plasmatron according to this invention produces a substantially large effective plasma discharge volume allowing for substantially greater volumetric efficiency in the initiation of chemical reactions within a volume of bulk fluid reactant flowing through the plasmatron.

Low current plasmatron fuel converter having enlarged volume discharges

DOEpatents

Rabinovich, Alexander [Swampscott, MA; Alexeev, Nikolai [Moscow, RU; Bromberg, Leslie [Sharon, MA; Cohn, Daniel R [Chestnut Hill, MA; Samokhin, Andrei [Moscow, RU

2009-10-06

A novel apparatus and method is disclosed for a plasmatron fuel converter ("plasmatron") that efficiently uses electrical energy to produce hydrogen rich gas. The volume and shape of the plasma discharge is controlled by a fluid flow established in a plasma discharge volume. A plasmatron according to this invention produces a substantially large effective plasma discharge volume allowing for substantially greater volumetric efficiency in the initiation of chemical reactions within a volume of bulk fluid reactant flowing through the plasmatron.

Controlled differential pressure system for an enhanced fluid blending apparatus

DOEpatents

Hallman, Jr., Russell Louis

2009-02-24

A system and method for producing a controlled blend of two or more fluids. Thermally-induced permeation through a permeable tube is used to mix a first fluid from outside the tube with a second fluid flowing through the tube. Mixture ratios may be controlled by adjusting the temperature of the first fluid or by adjusting the pressure drop through the permeable tube. The combination of a back pressure control valve and a differential regulator is used to control the output pressure of the blended fluid. The combination of the back pressure control valve and differential regulator provides superior flow control of the second dry gas. A valve manifold system may be used to mix multiple fluids, and to adjust the volume of blended fluid produced, and to further modify the mixture ratio.

Cardiac output-based fluid optimization for kidney transplant recipients: a proof-of-concept trial.

PubMed

Corbella, Davide; Toppin, Patrick Jason; Ghanekar, Anand; Ayach, Nour; Schiff, Jeffery; Van Rensburg, Adrian; McCluskey, Stuart A

2018-04-10

Intravenous fluid management for deceased donor kidney transplantation is an important, modifiable risk factor for delayed graft function (DGF). The primary objective of this study was to determine if goal-directed fluid therapy using esophageal Doppler monitoring (EDM) to optimize stroke volume (SV) would alter the amount of fluid given. This randomized, proof-of-concept trial enrolled 50 deceased donor renal transplant recipients. Data collected included patient characteristics, fluid administration, hemodynamics, and complications. The EDM was used to optimize SV in the EDM group. In the control group, fluid management followed the current standard of practice. The groups were compared for the primary outcome of total intraoperative fluid administered. There was no difference in the mean (standard deviation) volume of intraoperative fluid administered to the 24 control and 26 EDM patients [2,307 (750) mL vs 2,675 (842) mL, respectively; mean difference, 368 mL; 95% confidence interval (CI), - 87 to + 823; P = 0.11]. The incidence of complications in the control and EDM groups was similar (15/24 vs 17/26, respectively; P = 0.99), as was the incidence of delayed graft failure (8/24 vs 11/26, respectively; P = 0.36). Goal-directed fluid therapy did not alter the volume of fluid administered or the incidence of complications. This proof-of-concept trial provides needed data for conducting a larger trial to determine the influence of fluid therapy on the incidence in DGF in deceased donor kidney transplantation. www.clinicaltrials.gov (NCT02512731). Registered 31 July 2015.

Intraoperative intravascular volume optimisation and length of hospital stay after repair of proximal femoral fracture: randomised controlled trial.

PubMed Central

Sinclair, S.; James, S.; Singer, M.

1997-01-01

OBJECTIVES: To assess whether intraoperative intravascular volume optimisation improves outcome and shortens hospital stay after repair of proximal femoral fracture. DESIGN: Prospective, randomised controlled trial comparing conventional intraoperative fluid management with repeated colloid fluid challenges monitored by oesophageal Doppler ultrasonography to maintain maximal stroke volume throughout the operative period. SETTING: Teaching hospital, London. SUBJECTS: 40 patients undergoing repair of proximal femoral fracture under general anaesthesia. INTERVENTIONS: Patients were randomly assigned to receive either conventional intraoperative fluid management (control patients) or additional repeated colloid fluid challenges with oesophageal Doppler ultrasonography used to maintain maximal stroke volume throughout the operative period (protocol patients). MAIN OUTCOME MEASURES: Time declared medically fit for hospital discharge, duration of hospital stay (in acute bed; in acute plus long stay bed), mortality, perioperative haemodynamic changes. RESULTS: Intraoperative intravascular fluid loading produced significantly greater changes in stroke volume (median 15 ml (95% confidence interval 10 to 21 ml)) and cardiac output (1.2 l/min (0.1 to 2.3 l/min)) than in the conventionally managed group (-5 ml (-10 to 1 ml) and -0.4 l/min (-1.0 to 0.2 l/min)) (P < 0.001 and P < 0.05, respectively). One protocol patient and two control patients died in hospital. In the survivors, postoperative recovery was significantly faster in the protocol patients, with shorter times to being declared medically fit for discharge (median 10 (9 to 15) days v 15 (11 to 40) days, P < 0.05) and a 39% reduction in hospital stay (12 (8 to 13) days v 20 (10 to 61) days, P < 0.05). CONCLUSIONS: Proximal femoral fracture repair constitutes surgery in a high risk population. Intraoperative intravascular volume loading to optimal stroke volume resulted in a more rapid postoperative recovery and a significantly reduced hospital stay. PMID:9361539

Brain volume and cognitive function in patients with revascularized coronary artery disease.

PubMed

Ottens, Thomas H; Hendrikse, Jeroen; Nathoe, Hendrik M; Biessels, Geert Jan; van Dijk, Diederik

2017-03-01

The pathogenesis of cognitive dysfunction in patients with CAD remains unclear. CAD is associated with brain atrophy and specific lesions. Detailed knowledge about the association of brain volume measured with MRI, and cognitive function in patients with CAD is lacking. We therefore investigated brain volume and cognitive function in patients with revascularized coronary artery disease (CAD), and controls without CAD. Brain MRI scans and cognitive tests from patients with CAD were compared with data from control subjects without CAD. Cognitive performance was assessed with the Rey Auditory Verbal Learning (short term memory) and Trailmaking (divided attention) tests. Multivariable regression analysis was used to study associations between CAD, brain volume and cognitive function. A total of 102 patients with CAD and 48 control subjects were included. Level of education and age were comparable between the groups. Compared with controls, patients with CAD had smaller total brain volume (expressed as fraction of intracranial volume) [%ICV, mean (SD), 0.78 (0.03) vs 0.80 (0.02), P=0.001] and larger volume of non-ventricular cerebrospinal fluid [%ICV, median (IQR) 0.19 (0.18 to 0.21) vs 0.18 (0.17 to 0.20), P=0.001]. Patients in the CAD group had poorer cognitive function [mean (SD) Z-score -0.16 (0.72) vs 0.41 (0.69), P<0.01]. Multivariable regression showed that CAD, higher age, lower level of education and greater cerebrospinal fluid volume were independent predictors of poorer cognitive function. CAD patients had a smaller total brain volume and poorer cognitive function than controls. Greater volume of cerebrospinal fluid was an independent predictor of poorer cognitive function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Clinical Aspects of the Control of Plasma Volume at Microgravity and During Return to One Gravity

NASA Technical Reports Server (NTRS)

Convertino, Victor A.

1995-01-01

Plasma volume is reduced by 10%-20% within 24 to 48 h of exposure to simulated or actual microgravity. The clinical importance of microgravity-induced hypovolemia is manifested by its relationship with orthostatic intolerance and reduced VO2max after return to one gravity (1G). Since there is no evidence to suggest plasma volume reduction during microgravity is associated with thirst or renal dysfunctions, a diuresis induced by an immediate blood volume shift to the central circulation appears responsible for microgravity-induced hypovolemia. Since most astronauts choose to restrict their fluid intake before a space mission, absence of increased urine output during actual spaceflight may be explained by low central venous pressure (CVP) which accompanies dehydration. Compelling evidence suggests that prolonged reduction in CVP during exposure to microgravity reflects a 'resetting' to a lower operating point which acts to limit plasma volume expansion during attempts to increase fluid intake. In groudbase and spaceflight experiments, successful restoration and maintenance of plasma volume prior to returning to an upright posture may depend upon development of treatments that can return CVP to its baseline 10 operating point. Fluid-loading and LBNP have not proved completely effective in restoring plasma volume, suggesting that they may not provide the stimulus to elevate the CVP operating point. On the other, exercise, which can chronically increase CVP, has been effective in expanding plasma volume when combined with adequate dietary intake of fluid and electrolytes. The success of designing experiments to understand the physiological mechanisms of and development of effective countermeasures for the control of plasma volume in microgravity and during return to one gravity will depend upon testing that can be conducted under standardized controlled baseline condi

Restoration of plasma volume after 16 days of head-down tilt induced by a single bout of maximal exercise

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Engelke, K. A.; Ludwig, D. A.; Doerr, D. F.

1996-01-01

Seven healthy men performed maximal exercise 24 h before the end of 16 days exposure to 6 degrees head-down tilt (HDT) to test the hypothesis that such an exercise technique could restore plasma volume (PV) at the end of a simulated space mission. Exercise consisted of supine cycling with graded work rates increasing by 16 W/min to volitional fatigue and required an average of 16 min. The experimental protocol was a standard cross-over design in which the order of treatment (exercise or control) was counterbalanced across all seven subjects. PV, fluid intake (ad libitum), urine output, renal function, and hormones associated with fluid homeostasis were measured before HDT, 24 h before the end of HDT just prior to exercise, and at the end of HDT 24 h after exercise. HDT reduced PV by 16% in both control and exercise conditions. Maximal exercise completely restored plasma volume within 24 h to 3.9 +/- 3.2% of pre-HDT levels despite continued HDT. Compared with control, exercise induced a 660-ml larger positive fluid balance because of greater fluid intake and reduced urine volume during the 24 h after exercise. These results suggest that one bout of maximal leg exercise before return from 16 days of spaceflight may be completely effective in stimulating thirst and restoring plasma volume to preflight levels.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

2008-10-28

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, TX; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX; Coates, Don M [Santa Fe, NM

2011-05-31

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, TX; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX

2011-01-18

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

2010-06-29

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Controlling the pressure within an annular volume of a wellbore

DOEpatents

Hermes, Robert E [Los Alamos, NM; Gonzalez, Manuel E [Kingwood, NM; Llewellyn, Brian C [Kingwood, TX; Bloys, James B [Katy, TX; Coates, Don M [Santa Fe, NM

2011-06-21

A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Mathematical modeling of fluid-electrolyte alterations during weightlessness

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1984-01-01

Fluid electrolyte metabolism and renal endocrine control as it pertains to adaptation to weightlessness were studied. The mathematical models that have been particularly useful are discussed. However, the focus of the report is on the physiological meaning of the computer studies. A discussion of the major ground based analogs of weightlessness are included; for example, head down tilt, water immersion, and bed rest, and a comparison of findings. Several important zero g phenomena are described, including acute fluid volume regulation, blood volume regulation, circulatory changes, longer term fluid electrolyte adaptations, hormonal regulation, and body composition changes. Hypotheses are offered to explain the major findings in each area and these are integrated into a larger hypothesis of space flight adaptation. A conceptual foundation for fluid electrolyte metabolism, blood volume regulation, and cardiovascular regulation is reported.

Inhibition of the expression of aquaporin‑1 by RNA interference in pulmonary epithelial cells and its effects on water transport.

PubMed

Zhang, Qiuyue; Fu, Jianhua; Xue, Xindong

2016-01-01

In the present study, the effect of aquaporin‑1 (AQP1) on fluid transportation in pulmonary epithelial cells, and the role of AQP1 in alveolar fluid clearance were investigated to provide an experimental foundation to elucidate the pathogenesis of hyperoxic lung edema. An siRNA transfection technique was used to silence AQP1 in the A549 cell line. The transfected cells were randomized into a hyperoxia exposure and an air control group, with a negative control group set for each group. Cell volume was determined using flow cytometry, and Pf values were used to determine osmotic water permeability. Cell volume was found to be reduced in the AQP1‑silenced A549 cells, compared with the negative control group 72 h following air exposure. In addition, cell volume was reduced in the AQP1‑silenced A549 cells, compared with the negative control group 48 and 72 h following hyperoxia exposure. The osmotic water permeability of the AQP1‑silenced cells was reduced in the air control and hyperoxia exposure groups, compared with the negative control group 48 and 72 h following exposure. The volume and cell membrane osmotic water permeability of the A549 cells were reduced, compared with those in the control group following AQP1‑silencing, which indicated that the downregulation of AQP1 impedes extracellular to intracellular fluid transportation. Therefore, the disturbance in alveolar fluid clearance resulting from the downregulation of AQP1 following hyperoxia exposure may be one of the key mechanisms responsible for hyperoxic lung edema.

Goal-directed Fluid Therapy Does Not Reduce Primary Postoperative Ileus after Elective Laparoscopic Colorectal Surgery: A Randomized Controlled Trial.

PubMed

Gómez-Izquierdo, Juan C; Trainito, Alessandro; Mirzakandov, David; Stein, Barry L; Liberman, Sender; Charlebois, Patrick; Pecorelli, Nicolò; Feldman, Liane S; Carli, Franco; Baldini, Gabriele

2017-07-01

Inadequate perioperative fluid therapy impairs gastrointestinal function. Studies primarily evaluating the impact of goal-directed fluid therapy on primary postoperative ileus are missing. The objective of this study was to determine whether goal-directed fluid therapy reduces the incidence of primary postoperative ileus after laparoscopic colorectal surgery within an Enhanced Recovery After Surgery program. Randomized patient and assessor-blind controlled trial conducted in adult patients undergoing laparoscopic colorectal surgery within an Enhanced Recovery After Surgery program. Patients were assigned randomly to receive intraoperative goal-directed fluid therapy (goal-directed fluid therapy group) or fluid therapy based on traditional principles (control group). Primary postoperative ileus was the primary outcome. One hundred twenty-eight patients were included and analyzed (goal-directed fluid therapy group: n = 64; control group: n = 64). The incidence of primary postoperative ileus was 22% in the goal-directed fluid therapy and 22% in the control group (relative risk, 1; 95% CI, 0.5 to 1.9; P = 1.00). Intraoperatively, patients in the goal-directed fluid therapy group received less intravenous fluids (mainly less crystalloids) but a greater volume of colloids. The increase of stroke volume and cardiac output was more pronounced and sustained in the goal-directed fluid therapy group. Length of hospital stay, 30-day postoperative morbidity, and mortality were not different. Intraoperative goal-directed fluid therapy compared with fluid therapy based on traditional principles does not reduce primary postoperative ileus in patients undergoing laparoscopic colorectal surgery in the context of an Enhanced Recovery After Surgery program. Its previously demonstrated benefits might have been offset by advancements in perioperative care.

[The Contribution of Vascular Capacity and Blood Volume to Maintain Stable Blood Circulation during General Anesthesia].

PubMed

Shigemi, Kenji

2016-05-01

To maintain proper cardiac preload is one of the most effective procedures for the systemic circulation remaining stable. In particular, the balance between vascular capacity and total blood volume must be maintained within appropriate range by the administration of fluids, blood and/or vasoactive drugs with mean circulatory filling pressure (Pmcf), central venous pressure (CVP) or stroke volume variation (SVV). End-diastolic left ventricular volume (Ved) is theoretically the best index of cardiac preload; however, without transesophageal echocardbalanceiogram we cannot directly monitor Ved during anesthesia. The infused fluid volume remaining in intravascular space, the vascular capacity controlled by autonomic nervous system and/or vasoactive agents, and the unstressed blood volume properly mobilized to excess blood volume are the crucial factors to maintain cardiac output The knowledge of vascular physiology contribute the decision making to manipulate such factors to control blood circulation during general anesthesia. For example, CVP is usually maintained in the narrow range and seems to be stable; however, it must be changed just after the circulatory disturbances, such as acute bleeding, blood transfusion, and fluid infusion, and followed by gradual returning to initial value, because of the solid mechanism to preserve cardiac output

Effect of Volume of Fluid Resuscitation on Metabolic Normalization in Children Presenting in Diabetic Ketoacidosis: A Randomized Controlled Trial.

PubMed

Bakes, Katherine; Haukoos, Jason S; Deakyne, Sara J; Hopkins, Emily; Easter, Josh; McFann, Kim; Brent, Alison; Rewers, Arleta

2016-04-01

The optimal rate of fluid administration in pediatric diabetic ketoacidosis (DKA) is unknown. Our aim was to determine whether the volume of fluid administration in children with DKA influences the rate of metabolic normalization. We performed a randomized controlled trial conducted in a tertiary pediatric emergency department from December 2007 until June 2010. The primary outcome was time to metabolic normalization; secondary outcomes were time to bicarbonate normalization, pH normalization, overall length of hospital treatment, and adverse outcomes. Children between 0 and 18 years of age were eligible if they had type 1 diabetes mellitus and DKA. Patients were randomized to receive intravenous (IV) fluid at low volume (10 mL/kg bolus + 1.25 × maintenance rate) or high volume (20 mL/kg bolus + 1.5 × maintenance rate) (n = 25 in each). After adjusting for initial differences in bicarbonate levels, time to metabolic normalization was significantly faster in the higher-volume infusion group compared to the low-volume infusion group (hazard ratio [HR] = 2.0; 95% confidence interval [CI] 1.0-3.9; p = 0.04). Higher-volume IV fluid infusion appeared to hasten, to a greater extent, normalization of pH (HR = 2.5; 95% CI 1.2-5.0; p = 0.01) than normalization of serum bicarbonate (HR = 1.2; 95% CI 0.6-2.3; p = 0.6). The length of hospital treatment HR (0.8; 95% CI 0.4-1.5; p = 0.5) and time to discharge HR (0.8; 95% CI 0.4-1.5; p = 0.5) did not differ between treatment groups. Higher-volume fluid infusion in the treatment of pediatric DKA patients significantly shortened metabolic normalization time, but did not change overall length of hospital treatment. ClinicalTrials.gov ID NCT01701557. Copyright © 2016 Elsevier Inc. All rights reserved.

Accurate fluid force measurement based on control surface integration

NASA Astrophysics Data System (ADS)

Lentink, David

2018-01-01

Nonintrusive 3D fluid force measurements are still challenging to conduct accurately for freely moving animals, vehicles, and deforming objects. Two techniques, 3D particle image velocimetry (PIV) and a new technique, the aerodynamic force platform (AFP), address this. Both rely on the control volume integral for momentum; whereas PIV requires numerical integration of flow fields, the AFP performs the integration mechanically based on rigid walls that form the control surface. The accuracy of both PIV and AFP measurements based on the control surface integration is thought to hinge on determining the unsteady body force associated with the acceleration of the volume of displaced fluid. Here, I introduce a set of non-dimensional error ratios to show which fluid and body parameters make the error negligible. The unsteady body force is insignificant in all conditions where the average density of the body is much greater than the density of the fluid, e.g., in gas. Whenever a strongly deforming body experiences significant buoyancy and acceleration, the error is significant. Remarkably, this error can be entirely corrected for with an exact factor provided that the body has a sufficiently homogenous density or acceleration distribution, which is common in liquids. The correction factor for omitting the unsteady body force, {{{ {ρ f}} {1 - {ρ f} ( {{ρ b}+{ρ f}} )}.{( {{{{ρ }}b}+{ρ f}} )}}} , depends only on the fluid, {ρ f}, and body, {{ρ }}b, density. Whereas these straightforward solutions work even at the liquid-gas interface in a significant number of cases, they do not work for generalized bodies undergoing buoyancy in combination with appreciable body density inhomogeneity, volume change (PIV), or volume rate-of-change (PIV and AFP). In these less common cases, the 3D body shape needs to be measured and resolved in time and space to estimate the unsteady body force. The analysis shows that accounting for the unsteady body force is straightforward to non-intrusively and accurately determine fluid force in most applications.

Surface sampling concentration and reaction probe with controller to adjust sampling position

DOEpatents

Van Berkel, Gary J.; ElNaggar, Mariam S.

2016-07-19

A method of analyzing a chemical composition of a specimen is described. The method can include providing a probe comprising an outer capillary tube and an inner capillary tube disposed co-axially within the outer capillary tube, where the inner and outer capillary tubes define a solvent capillary and a sampling capillary in fluid communication with one another at a distal end of the probe; contacting a target site on a surface of a specimen with a solvent in fluid communication with the probe; maintaining a plug volume proximate a solvent-specimen interface, wherein the plug volume is in fluid communication with the probe; draining plug sampling fluid from the plug volume through the sampling capillary; and analyzing a chemical composition of the plug sampling fluid with an analytical instrument. A system for performing the method is also described.

Control volume based hydrocephalus research

NASA Astrophysics Data System (ADS)

Cohen, Benjamin; Voorhees, Abram; Wei, Timothy

2008-11-01

Hydrocephalus is a disease involving excess amounts of cerebral spinal fluid (CSF) in the brain. Recent research has shown correlations to pulsatility of blood flow through the brain. However, the problem to date has presented as too complex for much more than statistical analysis and understanding. This talk will highlight progress on developing a fundamental control volume approach to studying hydrocephalus. The specific goals are to select physiologically control volume(s), develop conservation equations along with the experimental capabilities to accurately quantify terms in those equations. To this end, an in vitro phantom is used as a simplified model of the human brain. The phantom's design consists of a rigid container filled with a compressible gel. The gel has a hollow spherical cavity representing a ventricle and a cylindrical passage representing the aquaducts. A computer controlled piston pump supplies pulsatile volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity, and volume change as functions of time. Independent pressure measurements and flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients.

The Aerothermodynamics of Aircraft Gas Turbine Engines

DTIC Science & Technology

1978-07-01

engine will deteriorate. 1.6.2 Experimental Testing It is easy to fall int9 the organiza- tional trap of four isolated groups . One group does the... Quasi -Dne-Dimensional Fluid Flows The First Law for a F1mdng System-- The Control Volume • . • The Channel Flow Equations Stagnation Properties...exit to control volume (Eq • 2. 14 . 2) CHAPTER TWO THERMODYNAMICS AND QUASI -ONE-DUlENSIONAL FLUID FLO’’{S 2.0 INTRODUCTION This chapter "ill be

Post-traumatic changes in, and effect of colloid osmotic pressure on the distribution of body water.

PubMed

Böck, J C; Barker, B C; Clinton, A G; Wilson, M B; Lewis, F R

1989-09-01

The aim of this study was to define the post-traumatic changes in body fluid compartments and to evaluate the effect of plasma colloid osmotic pressure (COP) on the partitioning of body fluid between these compartments. Forty-two measurements of plasma volume (green dye), extracellular volume (bromine), and total body water (deuterium) were done in ten traumatized patients (mean Injury Severity Score, ISS, = 34) and 23 similar control studies were done in eight healthy volunteers who were in stable fluid balance. Interstitial volume, intracellular volume, and blood volume were calculated from measured fluid spaces and hematocrit; COP was directly measured. Studies in volunteers on consecutive days indicated good reproducibility, with coefficients of variation equal to 3.5% for COP, 6.3% for plasma volume, 4.5% for extracellular volume, and 4.9% for total body water. COP values extended over the entire range seen clinically, from 10 to 30 mmHg. Interstitial volume was increased by 55% in patients, but intracellular volume was decreased by 10%. We conclude (1) that posttraumatic peripheral edema resulting from hemodilution is located in the interstitial compartment, with no intracellular space expansion; and (2) that interstitial volume, but not intracellular volume, is closely related to plasma COP.

Method and apparatus for controlling cross contamination of microfluid channels

DOEpatents

Hasselbrink, Jr., Ernest F.; Rehm, Jason E [Alameda, CA; Paul, Phillip H [Livermore, CA; Arnold, Don W [Livermore, CA

2006-02-07

A method for controlling fluid flow at junctions in microchannel systems. Control of fluid flow is accomplished generally by providing increased resistance to electric-field and pressure-driven flow in the form of regions of reduced effective cross-sectional area within the microchannels and proximate a channel junction. By controlling these flows in the region of a microchannel junction it is possible to eliminate sample dispersion and cross contamination and inject well-defined volumes of fluid from one channel to another.

Clinical aspects of the control of plasma volume at microgravity and during return to one gravity

NASA Technical Reports Server (NTRS)

Convertino, V. A.

1996-01-01

Plasma volume is reduced by 10-20% within 24-48 h of exposure to simulated or actual microgravity. The clinical importance of microgravity induced hypovolemia is manifested by its relationship with orthostatic intolerance and reduced maximal oxygen uptake (VO2max) after return to one gravity (1G). Since there is no evidence to suggest that plasma volume reduction during microgravity is associated with thirst or renal dysfunctions, a diuresis induced by an immediate blood volume shift to the central circulation appears responsible for microgravity-induced hypovolemia. Since most astronauts choose to restrict their fluid intake before a space mission, absence of increased urine output during actual space flight may be explained by low central venous pressure (CVP) which accompanies dehydration. Compelling evidence suggests that prolonged reduction in CVP during exposure to microgravity reflects a "resetting" to a lower operating point, which acts to limit plasma volume expansion during attempts to increase fluid intake. In ground based and space flight experiments, successful restoration and maintenance of plasma volume prior to returning to an upright posture may depend upon development of treatments that can return CVP to its baseline IG operating point. Fluid-loading and lower body negative pressure (LBNP) have not proved completely effective in restoring plasma volume, suggesting that they may not provide the stimulus to elevate the CVP operating point. On the other hand, exercise, which can chronically increase CVP, has been effective in expanding plasma volume when combined with adequate dietary intake of fluid and electrolytes. The success of designing experiments to understand the physiological mechanisms of and development of effective counter measures for the control of plasma volume in microgravity and during return to IG will depend upon testing that can be conducted under standardized controlled baseline conditions during both ground-based and space flight investigations.

A comprehensive Guyton model analysis of physiologic responses to preadapting the blood volume as a countermeasure to fluid shifts

NASA Technical Reports Server (NTRS)

Simanonok, K. E.; Srinivasan, R. S.; Myrick, E. E.; Blomkalns, A. L.; Charles, J. B.

1994-01-01

The Guyton model of fluid, electrolyte, and circulatory regulation is an extensive mathematical model capable of simulating a variety of experimental conditions. It has been modified for use at NASA to simulate head-down tilt, a frequently used analog of weightlessness. Weightlessness causes a headward shift of body fluids that is believed to expand central blood volume, triggering a series of physiologic responses resulting in large losses of body fluids. We used the modified Guyton model to test the hypothesis that preadaptation of the blood volume before weightless exposure could counteract the central volume expansion caused by fluid shifts, and thereby attenuate the circulatory and renal responses that result in body fluid losses. Simulation results show that circulatory preadaptation, by a procedure resembling blood donation immediately before head-down bedrest, is effective in damping the physiologic responses to fluid shifts and reducing body fluid losses. After 10 hours of head-down tilt, preadaptation also produces higher blood volume, extracellular volume, and total body water for 20 to 30 days of bedrest, compared with non-preadapted control. These results indicate that circulatory preadaptation before current Space Shuttle missions may be beneficial for the maintenance of reentry and postflight orthostatic tolerance in astronauts. This paper presents a comprehensive examination of the simulation results pertaining to changes in relevant physiologic variables produced by blood volume reduction before a prolonged head-down tilt. The objectives were to study and develop the countermeasure theoretically, to aid in planning experimental studies of the countermeasure, and to identify potentially disadvantageous physiologic responses that may be caused by the countermeasure.

A Mechanics-Based Framework Leading to Improved Diagnosis and Treatment of Hydrocephalus

NASA Astrophysics Data System (ADS)

Cohen, Benjamin; Soren, Vedels; Wagshul, Mark; Egnor, Michael; Voorhees, Abram; Wei, Timothy

2007-11-01

Hydrocephalus is defined as an accumulation of cerebrospinal fluid (CSF) in the cranium, at the expense of brain tissue. The result is a disruption of the normal pressure and/or flow dynamics of the intracranial blood and CSF. We seek to introduce integral control volume analysis to the study of hydrocephalus. The goal is to provide a first principles framework to integrate a broad spectrum of sometimes disparate investigations into a highly complex, multidisciplinary problem. The general technique for the implementation of control volumes to hydrocephalus will be presented. This includes factors faced in choosing control volumes and making the required measurements to evaluate mass and momentum conservation. In addition, the use of our Digital Particle Image Velocimetry (DPIV) processing program has been extended to measure the displacement of the ventricles' walls from Magnetic Resonance (MR) images. This is done to determine the volume change of the intracranial fluid spaces.

Crystalloid versus Colloid for Intraoperative Goal-directed Fluid Therapy Using a Closed-loop System: A Randomized, Double-blinded, Controlled Trial in Major Abdominal Surgery.

PubMed

Joosten, Alexandre; Delaporte, Amelie; Ickx, Brigitte; Touihri, Karim; Stany, Ida; Barvais, Luc; Van Obbergh, Luc; Loi, Patricia; Rinehart, Joseph; Cannesson, Maxime; Van der Linden, Philippe

2018-01-01

The type of fluid and volume regimen given intraoperatively both can impact patient outcome after major surgery. This two-arm, parallel, randomized controlled, double-blind, bi-center superiority study tested the hypothesis that when using closed-loop assisted goal-directed fluid therapy, balanced colloids are associated with fewer postoperative complications compared to balanced crystalloids in patients having major elective abdominal surgery. One hundred and sixty patients were enrolled in the protocol. All patients had maintenance-balanced crystalloid administration of 3 ml · kg · h. A closed-loop system delivered additional 100-ml fluid boluses (patients were randomized to receive either a balanced-crystalloid or colloid solution) according to a predefined goal-directed strategy, using a stroke volume and stroke volume variation monitor. All patients were included in the analysis. The primary outcome was the Post-Operative Morbidity Survey score, a nine-domain scale, at day 2 postsurgery. Secondary outcomes included all postoperative complications. Patients randomized in the colloid group had a lower Post-Operative Morbidity Survey score (median [interquartile range] of 2 [1 to 3] vs. 3 [1 to 4], difference -1 [95% CI, -1 to 0]; P < 0.001) and a lower incidence of postoperative complications. Total volume of fluid administered intraoperatively and net fluid balance were significantly lower in the colloid group. Under our study conditions, a colloid-based goal-directed fluid therapy was associated with fewer postoperative complications than a crystalloid one. This beneficial effect may be related to a lower intraoperative fluid balance when a balanced colloid was used. However, given the study design, the mechanism for the difference cannot be determined with certainty.

Electrochemical attosyringe.

PubMed

Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

2007-07-17

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

Electrochemical attosyringe

PubMed Central

Laforge, François O.; Carpino, James; Rotenberg, Susan A.; Mirkin, Michael V.

2007-01-01

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10−18 to 10−12 liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems. PMID:17620612

Feed intake, forestomach fluid volume, dilution rate and mean retention of fluid in the forestomach during water deprivation and rehydration in camels (Camelus sp.).

PubMed

von Engelhardt, W; Haarmeyer, P; Lechner-Doll, M

2006-04-01

Camels were deprived of water for 11 days. Before and during water deprivation and during rehydration changes in body weight, feed and water intake were measured. Using the liquid marker Cr-EDTA forestomach fluid volume, mean fluid retention and fluid dilution in the forestomach were estimated. At the eleventh day of water deprivation hay intake had decreased to only 9.6% of controls, dilution rates had decreased to 31%, mean retention time of fluid in the forestomach had increased to 189%. At the end of dehydration flow of saliva of 2 l/h mainly contributed to the still rather high dilution rates. Thereby buffering capacity and flow of fluid into the forestomach for microbial digestion as well as the outflow from the forestomach were maintained. At the beginning of rehydration camels drank 97 l within a few minutes, and animals thereby replaced all the water lost. Following this first huge water intake water is rapidly absorbed from the forestomach, and forestomach volume decreased again to dehydration values. At the third day of rehydration control values were reached again. Although feed intake decreased dramatically during water deprivation, functions of the forestomach can be maintained sufficiently mainly due to saliva inflow. This explains the mostly rapid recovery of camels when water is available again.

Developing a Control Strategy for Jets in Crossflow Using Direct Numerical Simulation

DTIC Science & Technology

2010-03-29

the total volume of scalar–containing fluid ( Vsc ) for stroke ratios equal to 2 and 6. Vsc is computed as the sum of all volume elements which have...concentration allows the difference between the scalar containing fluid and unmixed ambient fluid to be represented. Vsc can be considered as a measure of the...spread of the scalar in the flow–field. Figure 2.10(a) shows that Vsc increases nearly linearly (at a rate of 1.7) until t∗ ∼ 2. In general, Vsc

Effect of gum chewing on gastric volume and emptying: a prospective randomized crossover study.

PubMed

Bouvet, L; Loubradou, E; Desgranges, F-P; Chassard, D

2017-11-01

Current fasting guidelines allow oral intake of water up to 2 h before induction of anaesthesia. We assessed whether gum chewing affects gastric emptying of 250 ml water and residual gastric fluid volume measured 2 h after ingestion of water. This prospective randomized observer-blind crossover trial was performed on 20 healthy volunteers who attended two separate study sessions: Control and Chewing gum (chlorophyll flavour, with 2.1 g carbohydrate). Each session started with an ultrasound measurement of the antral area, followed by drinking 250 ml water. Then, volunteers either chewed a sugared gum for 45 min (Chewing gum) or did not (Control). Serial measurements of the antral area were performed during 120 min, and the half-time to gastric emptying (t½), total gastric emptying time, and gastric fluid volume before ingestion of water and 120 min later were calculated. Gastric emptying of water was not different between sessions; the mean (sdsd) t½ was 23 (10) min in the Control session and 21 (7) min in the Chewing gum session (P=0.52). There was no significant difference between sessions in gastric fluid volumes measured before ingestion of water and 120 min later. Chewing gum does not affect gastric emptying of water and does not change gastric fluid volume measured 2 h after ingestion of water. NCT02673307. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Exercise Increases the Cardiovascular Stimulus Provided by Artificial Gravity

NASA Technical Reports Server (NTRS)

Howarth, M. S.; Moore, F. B.; Hinghofer-Szalkay, H.; Jezova, D.; Diedrich, A.; Ferris, M. B.; Schlegel, T. T.; Pathwardhan, A. R.; Knapp, C. F.; Evans, J. M.

2008-01-01

We investigated fluid shifts and regulatory responses to variations of posture, exercise, Gz level and radius of rotation in subjects riding NASA Ames 20G centrifuge. Results are from 4 protocols that address radius and exercise effects only. Protocol A: After 10 min supine control, 12 healthy men (35 plus or minus 9 yr, 82.8 plus or minus 7.9 kg) were exposed to rotational 1 Gz (2.5 m radius) for 2 min followed by 20 min alternating between 1 and 1.25 Gz. Blood samples were taken pre and post spin. Protocol B: Same as A, but lower limb exercise (70% V02max) preceded ramps to 1.25 Gz. Protocol C: Same as A but radius of rotation 8.3 m. Protocol D: Same as B but at 8.3 m. The 8 subjects who completed all protocols, increased heart rate (HR) from control, on average, by: A: 5, B: 39, C: 11, D: 44 bpm. For thoracic fluid volume, (bioimpedance), the 8 subjects changed from control, on average: A: -394, B: -548, C: -537, D: -708 mL. For thigh fluid volume, changes from control, on average, were: A: -137, B: 129, C: -75, D: 159 mL. Hematocrit changes from control were: A: 2.3, B: 3.5, C: 2.3, D: 4.3 %. Radius effects were mild and included greater loss of fluid from the thorax, less fluid loss from the thigh and increased heart rate at the longer radius. Pre-acceleration exercise effects were more dramatic and included additional loss of fluid from the chest, increased fluid volume of the thigh, increased hematocrit and greater heart rate increases. We propose that short bouts of intense exercise can be used to magnify the cardiovascular stress delivered by artificial gravity (AG) training and the combination of AG with exercise training can be fine-tuned to preserve orthostatic tolerance of astronauts during spaceflight.

Hormonal and electrolyte responses to acute isohemic volume expansion in unanesthetized rats

NASA Technical Reports Server (NTRS)

Chenault, V. M.; Morris, M.; Lynch, C. D.; Maultsby, S. J.; Hutchins, P. M.

1993-01-01

This study was undertaken to explore the time course of the metabolic response to isohemic blood volume expansion (30%) in normotensive, unanesthetized Sprague-Dawley rats. Whole blood, drawn from a femoral artery catheter of conscious donor rats, was infused into the jugular vein of recipient rats. Blood samples were drawn from a carotid artery of recipient rats at time points beginning immediately post-volume expansion (IPVE) up through 5 days post-volume expansion (PVE). To characterize the attendant compensatory mechanisms, the plasma concentrations of electrolytes and fluid regulatory hormones were determined. Hematocrit began to raise IPVE and was significantly elevated above control IPVE 20, 30, 40, 60, and 90 min, and 2, 4, 6, 8, 12, and 24 hr PVE. Consistent with our current understanding of the hormonal response to excess volume, atrial natriuretic factor was significantly increased above the prevolume expansion (control) values 0-30 min PVE. Surprisingly, plasma aldosterone levels were significantly increased above control at 20 and 30 min and 6 hr PVE, whereas plasma renin activity was significantly decreased 30-40 min PVE. Plasma sodium was not changed from control values except for a significant increase at 6 hr post-volume expansion. Plasma potassium, osmolality, and arginine vasopressin levels were not altered by the volume expansion. These studies delineate the physiologic time scheme operative in the regulation of fluid volume during acute ischemic volume expansion.

Fluid-electrolyte shifts and maximal oxygen uptake in man at simulated altitude /2,287 m/

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Adams, W. C.; Juhos, L.

1978-01-01

Experiments were conducted on six trained distance runners (21-23 yr) subjected to an eight-day dietary control at sea level, followed by an eight-day stay in an altitude chamber (2287-m altitude) and a four-day recovery at sea level. Fluid and electrolyte shifts during exercise at altitude were evaluated to gain insight into the mechanism of reduction in working capacity. The results are discussed in terms of resting fluid volumes and blood constituents, maximal exercise variables, and maximal exercise fluid-electrolyte shifts. Since there are no significant changes in fluid balance or resting plasma volume (PV) at altitude, it is concluded that neither these nor the excessive PV shifts with exercise contribute to the reduction in maximal oxygen uptake at altitude. During altitude exposure the percent loss in PV is found to follow the percent reduction in maximal oxygen uptake; however, on the first day of recovery the percent change in PV remains depressed while maximal oxygen uptake returns to control levels.

Effect of dietary sodium on fluid/electrolyte regulation during bed rest

NASA Technical Reports Server (NTRS)

Williams, W. Jon; Schneider, Suzanne M.; Gretebeck, Randall J.; Lane, Helen W.; Stuart, Charles A.; Whitson, Peggy A.

2003-01-01

BACKGROUND: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning. HYPOTHESIS: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses. METHODS: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.0 +/- 0.06 g x d(-1) (174 mmol x d(-1)) (CONT; n = 6), 1.0 +/- 0.02 g x d(-1) (43 mmol x d(-1)) (LS; n = 6), or 10.0 +/- 0.04 g x d(-1) (430 mmol x d(-1)) (HS; n = 5) sodium diet before, during, and after 21 d of 6 degrees head-down BR. PV, total body water, urine volume and osmolality, POSM, and F/E controlling hormone concentrations were measured. RESULTS: In HS subjects, plasma renin activity (-92%), plasma/urinary aldosterone (-59%; -64%), and PV (-15.0%; 6.0 ml x kg(-1); p < 0.05) decreased while plasma atrial natriuretic peptide (+34%) and urine antidiuretic hormone (+24%) increased during BR (p < 0.05) compared with CONT. In LS, plasma renin activity (+166%), plasma aldosterone (+167%), plasma antidiuretic hormone (+19%), and urinary aldosterone (+335%) increased with no change in PV compared with CONT (p < 0.05). Total body water did not change in any of the subjects. CONCLUSIONS: Contrary to our hypothesis, increasing dietary sodium while controlling fluid intake during BR resulted in a greater loss of PV compared with the CONT subjects. Reducing dietary sodium while controlling fluid intake did not alter the PV response during BR compared with CONT subjects.

Effect of intraoperative transesophageal Doppler-guided fluid therapy versus central venous pressure-guided fluid therapy on renal allograft outcome in patients undergoing living donor renal transplant surgery: a comparative study.

PubMed

Srivastava, Divya; Sahu, Sandeep; Chandra, Abhilash; Tiwari, Tanmay; Kumar, Sanjay; Singh, P K

2015-12-01

Transesophageal Doppler (TED)-guided intraoperative fluid therapy has shown to noninvasively optimize intravascular volume and reduce postoperative morbidity. The aim of this study was to compare the effects of Doppler-guided intraoperative fluid administration and central venous pressure (CVP)-guided fluid therapy on renal allograft outcome and postoperative complications. A prospective nonrandomized active controlled study was conducted on end-stage renal disease patients scheduled for living donor renal transplant surgery. 110 patients received intraoperative fluid guided by corrected flow time (FTc) and variation in stroke volume values obtained by continuous TED monitoring. Data of 104 patients in whom intraoperative fluid administration was guided by CVP values were retrospectively obtained for a control. The amount of intraoperative fluid given in the study group (12.20 ± 4.24 ml/kg/h) was significantly lower than in the controls (22.21 ± 4.67 ml/kg/h). The amount of colloid used was also significantly less and fewer recipients were seen to require colloid (69 vs 85%). The mean arterial pressures were comparable throughout. CVP reached was 7.18 ± 3.17 mmHg in the study group. It was significantly higher in the controls (13.42 ± 3.12 mmHg). The postoperative graft function and rate of dysfunction were comparable. Side-effects like postoperative dyspnoea (4.8 vs 0%) and tissue edema (9.6 vs 2.7%) were higher in the controls. FTc-guided intraoperative fluid therapy achieved the same rate of immediate graft function as CVP-guided fluid therapy but used a significantly less amount of fluid. The incidence of postoperative complications related to fluid overload was also reduced. The use of TED may replace invasive central line insertions in the future.

Association between intravenous chloride load during resuscitation and in-hospital mortality among patients with SIRS.

PubMed

Shaw, Andrew D; Raghunathan, Karthik; Peyerl, Fred W; Munson, Sibyl H; Paluszkiewicz, Scott M; Schermer, Carol R

2014-12-01

Recent data suggest that both elevated serum chloride levels and volume overload may be harmful during fluid resuscitation. The purpose of this study was to examine the relationship between the intravenous chloride load and in-hospital mortality among patients with systemic inflammatory response syndrome (SIRS), with and without adjustment for the crystalloid volume administered. We conducted a retrospective analysis of 109,836 patients ≥ 18 years old that met criteria for SIRS and received fluid resuscitation with crystalloids. We examined the association between changes in serum chloride concentration, the administered chloride load and fluid volume, and the 'volume-adjusted chloride load' and in-hospital mortality. In general, increases in the serum chloride concentration were associated with increased mortality. Mortality was lowest (3.7%) among patients with minimal increases in serum chloride concentration (0-10 mmol/L) and when the total administered chloride load was low (3.5% among patients receiving 100-200 mmol; P < 0.05 versus patients receiving ≥ 500 mmol). After controlling for crystalloid fluid volume, mortality was lowest (2.6%) when the volume-adjusted chloride load was 105-115 mmol/L. With adjustment for severity of illness, the odds of mortality increased (1.094, 95% CI 1.062, 1.127) with increasing volume-adjusted chloride load (≥ 105 mmol/L). Among patients with SIRS, a fluid resuscitation strategy employing lower chloride loads was associated with lower in-hospital mortality. This association was independent of the total fluid volume administered and remained significant after adjustment for severity of illness, supporting the hypothesis that crystalloids with lower chloride content may be preferable for managing patients with SIRS.

Fluid therapy LiDCO controlled trial-optimization of volume resuscitation of extensively burned patients through noninvasive continuous real-time hemodynamic monitoring LiDCO.

PubMed

Tokarik, Monika; Sjöberg, Folke; Balik, Martin; Pafcuga, Igor; Broz, Ludomir

2013-01-01

This pilot trial aims at gaining support for the optimization of acute burn resuscitation through noninvasive continuous real-time hemodynamic monitoring using arterial pulse contour analysis. A group of 21 burned patients meeting preliminary criteria (age range 18-75 years with second- third- degree burns and TBSA ≥10-75%) was randomized during 2010. A hemodynamic monitoring through lithium dilution cardiac output was used in 10 randomized patients (LiDCO group), whereas those without LiDCO monitoring were defined as the control group. The modified Brooke/Parkland formula as a starting resuscitative formula, balanced crystalloids as the initial solutions, urine output of 0.5 ml/kg/hr as a crucial value of adequate intravascular filling were used in both groups. Additionally, the volume and vasopressor/inotropic support were based on dynamic preload parameters in the LiDCO group in the case of circulatory instability and oligouria. Statistical analysis was done using t-tests. Within the first 24 hours postburn, a significantly lower consumption of crystalloids was registered in LiDCO group (P = .04). The fluid balance under LiDCO control in combination with hourly diuresis contributed to reducing the cumulative fluid balance approximately by 10% compared with fluid management based on standard monitoring parameters. The amount of applied solutions in the LiDCO group got closer to Brooke formula whereas the urine output was at the same level in both groups (0.8 ml/kg/hr). The new finding in this study is that when a fluid resuscitation is based on the arterial waveform analysis, the initial fluid volume provided was significantly lower than that delivered on the basis of physician-directed fluid resuscitation (by urine output and mean arterial pressure).

Flow-Control Unit For Nitrogen And Hydrogen Gases

NASA Technical Reports Server (NTRS)

Chang, B. J.; Novak, D. W.

1990-01-01

Gas-flow-control unit installed and removed as one piece replaces system that included nine separately serviced components. Unit controls and monitors flows of nitrogen and hydrogen gases. Designed for connection via fluid-interface manifold plate, reducing number of mechanical fluid-interface connections from 18 to 1. Unit provides increasing reliability, safety, and ease of maintenance, and for reducing weight, volume, and power consumption.

A new model of reaction-driven cracking: fluid volume consumption and tensile failure during serpentinization

NASA Astrophysics Data System (ADS)

Eichenbaum-Pikser, J. M.; Spiegelman, M. W.; Kelemen, P. B.; Wilson, C. R.

2013-12-01

Reactive fluid flow plays an important role in a wide range of geodynamic processes, such as melt migration, formation of hydrous minerals on fault surfaces, and chemical weathering. These processes are governed by the complex coupling between fluid transport, reaction, and solid deformation. Reaction-driven cracking is a potentially critical feedback mechanism, by which volume change associated with chemical reaction drives fracture in the surrounding rock. It has been proposed to play a role in both serpentinization and carbonation of peridotite, motivating consideration of its application to mineral carbon sequestration. Previous studies of reactive cracking have focused on the increase in solid volume, and as such, have considered failure in compression. However, if the consumption of fluid is considered in the overall volume budget, the reaction can be net volume reducing, potentially leading to failure in tension. To explore these problems, we have formulated and solved a 2-D model of coupled porous flow, reaction kinetics, and elastic deformation using the finite element model assembler TerraFERMA (Wilson et al, G3 2013 submitted). The model is applied to the serpentinization of peridotite, which can be reasonably approximated as the transfer of a single reactive component (H2O) between fluid and solid phases, making it a simple test case to explore the process. The behavior of the system is controlled by the competition between the rate of volume consumption by the reaction, and the rate of volume replacement by fluid transport, as characterized by a nondimensional parameter χ, which depends on permeability, reaction rate, and the bulk modulus of the solid. Large values of χ correspond to fast fluid transport relative to reaction rate, resulting in a low stress, volume replacing regime. At smaller values of χ, fluid transport cannot keep up with the reaction, resulting in pore fluid under-pressure and tensile solid stresses. For the range of χ relevant to the serpentinization of peridotite, these stresses can reach hundreds of MPa, exceeding the tensile strength of peridotite.

30 CFR 250.614 - Well-control fluids, equipment, and operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... well is shut in and secured. (b) When coming out of the hole with drill pipe or a workover string, the... string and drill collars that may be pulled prior to filling the hole and the equivalent well-control... fluid volumes when filling the hole on trips; and (3) A recording mud-pit-level indicator to determine...

Pump having pistons and valves made of electroactive actuators

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph (Inventor)

1997-01-01

The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

Cardiovascular response to lower body negative pressure stimulation before, during, and after space flight

NASA Technical Reports Server (NTRS)

Baisch, F.; Beck, L.; Blomqvist, G.; Wolfram, G.; Drescher, J.; Rome, J. L.; Drummer, C.

2000-01-01

BACKGROUND: It is well known that space travel cause post-flight orthostatic hypotension and it was assumed that autonomic cardiovascular control deteriorates in space. Lower body negative pressure (LBNP) was used to assess autonomic function of the cardiovascular system. METHODS: LBNP tests were performed on six crew-members before and on the first days post-flight in a series of three space missions. Additionally, two of the subjects performed LBNP tests in-flight. LBNP mimics fluid distribution of upright posture in a gravity independent way. It causes an artificial sequestration of blood, reduces preload, and filtrates plasma into the lower part of the body. Fluid distribution was assessed by bioelectrical impedance and anthropometric measurements. RESULTS: Heart rate, blood pressure, and total peripheral resistance increased significantly during LBNP experiments in-flight. The decrease in stroke volume, the increased pooling of blood, and the increased filtration of plasma into the lower limbs during LBNP indicated that a plasma volume reduction and a deficit of the interstitial volume of lower limbs rather than a change in cardiovascular control was responsible for the in-flight response. Post-flight LBNP showed no signs of cardiovascular deterioration. The still more pronounced haemodynamic changes during LBNP reflected the expected behaviour of cardiovascular control faced with less intravascular volume. In-flight, the status of an intra-and extravascular fluid deficit increases sympathetic activity, the release of vasoactive substances and consequently blood pressure. Post-flight, blood pressure decreases significantly below pre-flight values after restoration of volume deficits. CONCLUSION: We conclude that the cardiovascular changes in-flight are a consequence of a fluid deficit rather than a consequence of changes in autonomic signal processing.

Efficacy of intravenous fluid warming during goal-directed fluid therapy in patients undergoing laparoscopic colorectal surgery: a randomized controlled trial.

PubMed

Choi, Ji-Won; Kim, Duk-Kyung; Lee, Seung-Won; Park, Jung-Bo; Lee, Gyu-Hong

2016-06-01

To evaluate the clinical efficacy of intravenous (IV) fluid warming in patients undergoing laparoscopic colorectal surgery. Adult patients undergoing laparoscopic colorectal surgery were randomly assigned to receive either IV fluids at room temperature (control group) or warmed IV fluids (warm fluids group). Each patient received a standardized goal-directed fluid regimen based on stroke volume variances. Oesophageal temperature was measured at 15 min intervals for 2 h after induction of anaesthesia. A total of 52 patients were enrolled in the study. The drop in core temperature in the warm fluids group was significantly less than in the control group 2 h after the induction of anaesthesia. This significant difference was seen from 30 min after induction. IV fluid warming was associated with a smaller drop in core temperature than room temperature IV fluids in laparoscopic colorectal surgery incorporating goal-directed fluid therapy. © The Author(s) 2016.

Control volume based hydrocephalus research; a phantom study

NASA Astrophysics Data System (ADS)

Cohen, Benjamin; Voorhees, Abram; Madsen, Joseph; Wei, Timothy

2009-11-01

Hydrocephalus is a complex spectrum of neurophysiological disorders involving perturbation of the intracranial contents; primarily increased intraventricular cerebrospinal fluid (CSF) volume and intracranial pressure are observed. CSF dynamics are highly coupled to the cerebral blood flows and pressures as well as the mechanical properties of the brain. Hydrocephalus, as such, is a very complex biological problem. We propose integral control volume analysis as a method of tracking these important interactions using mass and momentum conservation principles. As a first step in applying this methodology in humans, an in vitro phantom is used as a simplified model of the intracranial space. The phantom's design consists of a rigid container filled with a compressible gel. Within the gel a hollow spherical cavity represents the ventricular system and a cylindrical passage represents the spinal canal. A computer controlled piston pump supplies sinusoidal volume fluctuations into and out of the flow phantom. MRI is used to measure fluid velocity and volume change as functions of time. Independent pressure measurements and momentum flow rate measurements are used to calibrate the MRI data. These data are used as a framework for future work with live patients and normal individuals. Flow and pressure measurements on the flow phantom will be presented through the control volume framework.

Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

DOEpatents

Fernandez, Carlos A.; Heldebrant, David J.; Bonneville, Alain H. R.; Jung, Hun Bok; Carroll, Kenneth

2016-09-20

An electrophilic acid gas-reactive fracturing and recovery fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. Proppants stabilize openings in fractures and fissures following fracturing.

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by 1H-MR Imaging and Spectroscopy.

PubMed

Biller, A; Reuter, M; Patenaude, B; Homola, G A; Breuer, F; Bendszus, M; Bartsch, A J

2015-12-01

As yet, there are no in vivo data on tissue water changes and associated morphometric changes involved in the osmo-adaptation of normal brains. Our aim was to evaluate osmoadaptive responses of the healthy human brain to osmotic challenges of de- and rehydration by serial measurements of brain volume, tissue fluid, and metabolites. Serial T1-weighted and (1)H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, on 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. MR imaging data were analyzed by using FreeSurfer and LCModel. On dehydration, serum osmolality increased by 0.67% and brain tissue fluid decreased by 1.63%, on average. MR imaging morphometry demonstrated corresponding decreases of cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus. These changes reversed during rehydration. Continuous fluid ingestion of 1 L of water for 1 hour within the scanner lowered serum osmolality by 0.96% and increased brain tissue fluid by 0.43%, on average. Concomitantly, cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus increased. Changes in brain tissue fluid were related to volume changes of the whole brain, the white matter, and hypothalamus/thalamus. Only volume changes of the hypothalamus/thalamus significantly correlated with serum osmolality. This is the first study simultaneously evaluating changes in brain tissue fluid, metabolites, volume, and cortical thickness. Our results reflect cellular volume regulatory mechanisms at a macroscopic level and emphasize that it is essential to control for hydration levels in studies on brain morphometry and metabolism in order to avoid confounding the findings. © 2015 by American Journal of Neuroradiology.

Application of Control Volume Analysis to Cerebrospinal Fluid Dynamics

NASA Astrophysics Data System (ADS)

Wei, Timothy; Cohen, Benjamin; Anor, Tomer; Madsen, Joseph

2011-11-01

Hydrocephalus is among the most common birth defects and may not be prevented nor cured. Afflicted individuals face serious issues, which at present are too complicated and not well enough understood to treat via systematic therapies. This talk outlines the framework and application of a control volume methodology to clinical Phase Contrast MRI data. Specifically, integral control volume analysis utilizes a fundamental, fluid dynamics methodology to quantify intracranial dynamics within a precise, direct, and physically meaningful framework. A chronically shunted, hydrocephalic patient in need of a revision procedure was used as an in vivo case study. Magnetic resonance velocity measurements within the patient's aqueduct were obtained in four biomedical state and were analyzed using the methods presented in this dissertation. Pressure force estimates were obtained, showing distinct differences in amplitude, phase, and waveform shape for different intracranial states within the same individual. Thoughts on the physiological and diagnostic research and development implications/opportunities will be presented.

Servo-control of water and sodium homeostasis during renal clearance measurements in conscious rats.

PubMed

Thomsen, Klaus; Shirley, David G

2007-01-01

Servo-controlled fluid and sodium replacement during clearance studies is used in order to prevent loss of body fluid and sodium following diuretic/natriuretic procedures. However, even under control conditions, the use of this technique is sometimes associated with increases in proximal tubular fluid output (assessed by lithium clearance) and excretion rates. The present study examined the reason for these increases. The first series of experiments showed that one cause is volume overloading. This can occur if the servo system is activated from the start, i.e., during the establishment of a suitably high urine flow rate by constant infusion of hypotonic glucose solution. The second series of experiments showed that replacement of blood samples with donor blood can also lead to increases in fractional lithium excretion and accompanying increases in water and sodium excretion, a problem not seen when blood samples are replaced with the animal's own red blood cells resuspended in isotonic saline. When these pitfalls are avoided, servo-controlled sodium and fluid replacement is a reliable technique that makes it possible to study the effects of natriuretic and/or diuretic stimuli without interference from unwanted changes in extracellular volume. 2007 S. Karger AG, Basel

A randomised controlled trial of fluid restriction compared to oesophageal Doppler-guided goal-directed fluid therapy in elective major colorectal surgery within an Enhanced Recovery After Surgery program.

PubMed

Phan, T D; D'Souza, B; Rattray, M J; Johnston, M J; Cowie, B S

2014-11-01

There is continued controversy regarding the benefits of goal-directed fluid therapy, with earlier studies showing marked improvement in morbidity and length-of-stay that have not been replicated more recently. The aim of this study was to compare patient outcomes in elective colorectal surgery patients having goal-directed versus restrictive fluid therapy. Inclusion criteria included suitability for an Enhanced Recovery After Surgery care pathway and patients with an American Society of Anesthesiologists Physical Status score of 1 to 3. Patients were intraoperatively randomised to either restrictive or Doppler-guided goal-directed fluid therapy. The primary outcome was length-of-stay; secondary outcomes included complication rate, change in haemodynamic variables and fluid volumes. Compared to restrictive therapy, goal-directed therapy resulted in a greater volume of intraoperative fluid, 2115 (interquartile range 1350 to 2560) ml versus 1500 (1200 to 2000) ml, P=0.008, and was associated with an increase in Doppler-derived stroke volume index from beginning to end of surgery, 43.7 (16.3) to 54.2 (21.1) ml/m(2), P <0.001, in the latter group. Length-of-stay was similar, 6.5 (5 to 9) versus 6 (4 to 9) days, P=0.421. The number of patients with any complication (minor or major) was similar; 0% (30) versus 52% (26), P=0.42, or major complications, 1 (2%) versus 4 (8%), P=0.36, respectively. The increased perioperative fluid volumes and increased stroke volumes at the end of surgery in patients receiving goal-directed therapy did not translate to a significant difference in length-of-stay and we did not observe a difference in the number of patients experiencing minor or major complications.

Stroke volume variation as a guide for fluid resuscitation in patients undergoing large-volume liposuction.

PubMed

Jain, Anil Kumar; Khan, Asma M

2012-09-01

: The potential for fluid overload in large-volume liposuction is a source of serious concern. Fluid management in these patients is controversial and governed by various formulas that have been advanced by many authors. Basically, it is the ratio of what goes into the patient and what comes out. Central venous pressure has been used to monitor fluid therapy. Dynamic parameters, such as stroke volume and pulse pressure variation, are better predictors of volume responsiveness and are superior to static indicators, such as central venous pressure and pulmonary capillary wedge pressure. Stroke volume variation was used in this study to guide fluid resuscitation and compared with one guided by an intraoperative fluid ratio of 1.2 (i.e., Rohrich formula). : Stroke volume variation was used as a guide for intraoperative fluid administration in 15 patients subjected to large-volume liposuction. In another 15 patients, fluid resuscitation was guided by an intraoperative fluid ratio of 1.2. The amounts of intravenous fluid administered in the groups were compared. : The mean amount of fluid infused was 561 ± 181 ml in the stroke volume variation group and 2383 ± 1208 ml in the intraoperative fluid ratio group. The intraoperative fluid ratio when calculated for the stroke volume variation group was 0.936 ± 0.084. All patients maintained hemodynamic parameters (heart rate and systolic, diastolic, and mean blood pressure). Renal and metabolic indices remained within normal limits. : Stroke volume variation-guided fluid application could result in an appropriate amount of intravenous fluid use in patients undergoing large-volume liposuction. : Therapeutic, II.

Endocrine and fluid metabolism in males and females of different ages after bedrest, acceleration and lower body negative pressure

NASA Technical Reports Server (NTRS)

Leach, C. S.; Vernikos-Danellis, J.; Krauhs, J. M.; Sandler, H.

1985-01-01

Space shuttle flight simulations were conducted to determine the effects of weightlessness, lower body negative pressure (LBNP), and acceleration of fluid and electrolyte excretion and the hormones that control it. Measurements were made on male and female subjects of different ages before and after bedrest. After admission to a controlled environment, groups of 6 to 14 subjects in the age ranges 25 to 35, 35 to 45, 45 to 55 to 65 years were exposed to +3 G sub z for 15 minutes (G1) and to LBNP (LBNP1) on different days. On 3 days during this prebedrest period, no tests were conducted. Six days of bedrest followed, and the G sub z (G2) and LBNP (LBNP2) tests were run again. Hormones, electrolytes, and other parameters were measured in 24-hour urine pools throughout the experiment. During bedrest, cortisol and aldosterone excretion increased. Urine volume decreased, and specific gravity and osmolality increased. Urinary electrolytes were statistically unchanged from levels during the non-stress control period. During G2, cortisol increased significantly over its control and bedrest levels. Urine volume, sodium, and chloride were significantly lower; specific gravity and osmolality were higher during the control period or bedrest. The retention of fluids and electrolytes after +G sub z may at least partially explain decreased urine volume and increased osmolality observed during bedrest in this study. There were some who indicated that space flight would not affect the fluid and electrolyte metabolism of females or older males any more severely than it has affected that of male astronauts.

Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandez, Carlos A.; Heldebrant, David J.; Bonneville, Alain

An electrophilic acid gas-reactive fracturing fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. The proppant stabilizes fracture openings in the bedrock to enhance recovery of energy-producing materials.

Adenovirus-mediated hAQP1 expression in irradiated mouse salivary glands causes recovery of saliva secretion by enhancing acinar cell volume decrease

PubMed Central

Teos, LY; Zheng, C-Y; Liu, X; Swaim, WD; Goldsmith, CM; Cotrim, AP; Baum, BJ; Ambudkar, IS

2017-01-01

Head and neck irradiation (IR) during cancer treatment causes by-stander effects on the salivary glands leading to irreversible loss of saliva secretion. The mechanism underlying loss of fluid secretion is not understood and no adequate therapy is currently available. Delivery of an adenoviral vector encoding human aquaporin-1 (hAQP1) into the salivary glands of human subjects and animal models with radiation-induced salivary hypofunction leads to significant recovery of saliva secretion and symptomatic relief in subjects. To elucidate the mechanism underlying loss of salivary secretion and the basis for AdhAQP1-dependent recovery of salivary gland function we assessed submandibular gland function in control mice and mice 2 and 8 months after treatment with a single 15-Gy dose of IR (delivered to the salivary gland region). Salivary secretion and neurotransmitter-stimulated changes in acinar cell volume, an in vitro read-out for fluid secretion, were monitored. Consistent with the sustained 60% loss of fluid secretion following IR, a carbachol (CCh)-induced decrease in acinar cell volume from the glands of mice post IR was transient and attenuated as compared with that in cells from non-IR age-matched mice. The hAQP1 expression in non-IR mice induced no significant effect on salivary fluid secretion or CCh-stimulated cell volume changes, except in acinar cells from 8-month group where the initial rate of cell shrinkage was increased. Importantly, the expression of hAQP1 in the glands of mice post IR induced recovery of salivary fluid secretion and a volume decrease in acinar cells to levels similar to those in cells from non-IR mice. The initial rates of CCh-stimulated cell volume reduction in acinar cells from hAQP1-expressing glands post IR were similar to those from control cells. Altogether, the data suggest that expression of hAQP1 increases the water permeability of acinar cells, which underlies the recovery of fluid secretion in the salivary glands functionally compromised post IR. PMID:26966862

[Effect of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat].

PubMed

Liu, Liang-ming; Hu, De-yao; Liu, Jian-cang; Li, Ping; Liu, Hou-dong; Xiao, Nan; Zhou, Xue-wu; Tian, Kun-lun; Huo, Xiao-ping; Shi, Quan-gui; He, Yan-mei; Yin, Zuo-ming

2003-05-01

To study the effects of different volumes of fluid resuscitation on hemorrhagic shock with pulmonary edema at high altitude in the unacclimated rat. One hundred and twenty-six SD rats transported to Lasa, Tibet, 3 760 meters above the sea level, were anesthetized one week later with sodium pentobarbital (30 mg/kg, intraperitoneal). Hemorrhagic shock with pulmonary edema model was induced by hemorrhage (50 mm Hg for 1 hour, 1 mmHg=0.133 kPa) plus intravenous injection of oleic acid (50 microl/kg). Experiments were then conducted in two parts. Sixty-three rats in part I were equally divided into nine groups (n=7): normal control, hemorrhagic shock control, hemorrhagic shock with pulmonary edema (HSPE) without fluid infusion, HSPE plus infusing lactated Ringer's solution (LR) with 0.5-, 1-, 1.5-, 2- or 3- fold volume shed blood, and 1 volume of LR plus mannitol (10 ml/kg). Hemodynamic parameters including mean arterial blood pressure (MAP), left intraventricular systolic pressure (LVSP) and the maximal change rate of intraventricular pressure rise or decline (+/- dp/dt max) were observed at 15, 30, 60 and 120 minutes after infusion, blood gases were measured at 30 and 120 minutes after infusion and the water content of lung and brain was determined at 120 minutes after infusion. In part II, additional 63 rats were used to observe the effect of different volumes of fluid resuscitation on survival time of HSPE rats. 0.5 volume of LR infusion significantly improved MAP, LVSP and +/- dp/dt max, prolonged the survival time of HSPE animals (all P<0.01), while it did not increase the water content of lung and brain and had no marked influence on blood gases. One volume of LR infusion slightly improved hemodynamic parameters, prolonged the survival time and increased the water content of lung. More than 1 volume of LR infusion including 1.5-, 2- and 3- fold volume LR deteriorated the hemodynamic parameters and decreased the survival time of shocked animal, meanwhile they apparently increased the water content of lung. One volume of LR plus mannitol (10 ml/kg) infusion did not improve the hemodynamic parameters and blood gases; also it did not decrease the water content of lung. The tolerance to fluid infusion for the unacclimated animal subjected to hemorrhagic shock with pulmonary edema at high altitude is significantly decreased. 0.5-1 volume of LR infusion appears to be beneficial effect on resuscitation at high altitude, while over 1 volume of LR infusion would aggravate pulmonary edema and exacerbate fluid resuscitation effect.

Influence of occlusal loading on peri-implant clinical parameters. A pilot study

PubMed Central

Pellicer-Chover, Hilario; Viña-Almunia, José; Romero-Millán, Javier; Peñarrocha-Oltra, David; Peñarrocha-Diago, María

2014-01-01

Objectives: To investigate the relation between occlusal loading and peri-implant clinical parameters (probing depth, bleeding on probing, gingival retraction, width of keratinized mucosa, and crevicular fluid volume) in patients with implant-supported complete fixed prostheses in both arches. Material and Methods: This clinical study took place at the University of Valencia (Spain) dental clinic. It included patients attending the clinic for regular check-ups during at least 12 months after rehabilitation of both arches with implant-supported complete fixed ceramo-metallic prostheses. One study implant and one control implant were established for each patient using the T-Scan®III computerized system (Tesco, South Boston, USA). The maxillary implant closest to the point of maximum occlusal loading was taken as the study implant and the farthest (with least loading) as the control. Occlusal forces were registered with the T-Scan® III and then occlusal adjustment was performed to distribute occlusal forces correctly. Peri-implant clinical parameters were analyzed in both implants before and two and twelve months after occlusal adjustment. Results: Before occlusal adjustment, study group implants presented a higher mean volume of crevicular fluid (51.3±7.4 UP) than the control group (25.8±5.5 UP), with statistically significant difference. Two months after occlusal adjustment, there were no significant differences between groups (24.6±3.8 UP and 26±4.5 UP respectively) (p=0.977). After twelve months, no significant differences were found between groups (24.4±11.1 UP and 22.5±8.9 UP respectively) (p=0.323). For the other clinical parameters, no significant differences were identified between study and control implants at any of the study times (p>0.05). Conclusions: Study group implants receiving higher occlusal loading presented significantly higher volumes of crevicular fluid than control implants. Crevicular fluid volumes were similar in both groups two and twelve months after occlusal adjustment. Key words:Occlusal loading, crevicular fluid, peri-implant clinical parameters, T-Scan®. PMID:24316708

Is there resetting of central venous pressure in microgravity?

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Ludwig, D. A.; Elliott, J. J.; Wade, C. E.

2001-01-01

In the early phase of the Space Shuttle program, NASA flight surgeons implemented a fluid-loading countermeasure in which astronauts were instructed to ingest eight 1-g salt tablets with 960 ml of water approximately 2 hours prior to reentry from space. This fluid loading regimen was intended to enhance orthostatic tolerance by replacing circulating plasma volume reduced during the space mission. Unfortunately, fluid loading failed to replace plasma volume in groundbased experiments and has proven minimally effective as a countermeasure against post-spaceflight orthostatic intolerance. In addition to the reduction of plasma volume, central venous pressure (CVP) is reduced during exposure to actual and groundbased analogs of microgravity. In the present study, we hypothesized that the reduction in CVP due to exposure to microgravity represents a resetting of the CVP operating point to a lower threshold. A lower CVP 'setpoint' might explain the failure of fluid loading to restore plasma volume. In order to test this hypothesis, we conducted an investigation in which we administered an acute volume load (stimulus) and measured responses in CVP, plasma volume and renal functions. If our hypothesis is true, we would expect the elevation in CVP induced by saline infusion to return to its pre-infusion levels in both HDT and upright control conditions despite lower vascular volume during HDT. In contrast to previous experiments, our approach is novel in that it provides information on alterations in CVP and vascular volume during HDT that are necessary for interpretation of the proposed CVP operating point resetting hypothesis.

Imbibition of hydraulic fracturing fluids into partially saturated shale

NASA Astrophysics Data System (ADS)

Birdsell, Daniel T.; Rajaram, Harihar; Lackey, Greg

2015-08-01

Recent studies suggest that imbibition of hydraulic fracturing fluids into partially saturated shale is an important mechanism that restricts their migration, thus reducing the risk of groundwater contamination. We present computations of imbibition based on an exact semianalytical solution for spontaneous imbibition. These computations lead to quantitative estimates of an imbibition rate parameter (A) with units of LT-1/2 for shale, which is related to porous medium and fluid properties, and the initial water saturation. Our calculations suggest that significant fractions of injected fluid volumes (15-95%) can be imbibed in shale gas systems, whereas imbibition volumes in shale oil systems is much lower (3-27%). We present a nondimensionalization of A, which provides insights into the critical factors controlling imbibition, and facilitates the estimation of A based on readily measured porous medium and fluid properties. For a given set of medium and fluid properties, A varies by less than factors of ˜1.8 (gas nonwetting phase) and ˜3.4 (oil nonwetting phase) over the range of initial water saturations reported for the Marcellus shale (0.05-0.6). However, for higher initial water saturations, A decreases significantly. The intrinsic permeability of the shale and the viscosity of the fluids are the most important properties controlling the imbibition rate.

Sustained hyperhydration with glycerol ingestion.

PubMed

Koenigsberg, P S; Martin, K K; Hlava, H R; Riedesel, M L

1995-01-01

Heavy exercise lasting more than three hours tends to result in dehydration, as the fluid intake is less than fluid loss by sweat and urine. Dehydration as small as one percent of body weight has been reported to decrease work capacity. In present and previous studies insensible water loss and sweat are assumed to be the same in both control and experimental conditions. Fluid intake less urine volume is utilized as an indicator of euhydration, hypohydration, or hyperhydration. Previous studies involving glycerol intake describe hyperhydration for 4.5 to 8 hours. The objective of this study was to keep subjects hyperhydrated (retention of water) for 32 or 49 hours. The experimental protocol involved ingestion of a large volume of fluid (39.2 or 51.1 ml/kg/d) with glycerol (2.9 to 3.1 g/kg/d) and without glycerol. In both Series I (49 h) and Series II (32 h) experiments, the intake of glycerol resulted in smaller urine volumes. This study demonstrates it is possible to keep human subjects hyperhydrated for extended periods of time and thereby reduce the amount of fluid consumption necessary just prior to or during bouts of negative fluid balance situations.

Preliminary results from a four-working space, double-acting piston, Stirling engine controls model

NASA Technical Reports Server (NTRS)

Daniele, C. J.; Lorenzo, C. F.

1980-01-01

A four working space, double acting piston, Stirling engine simulation is being developed for controls studies. The development method is to construct two simulations, one for detailed fluid behavior, and a second model with simple fluid behaviour but containing the four working space aspects and engine inertias, validate these models separately, then upgrade the four working space model by incorporating the detailed fluid behaviour model for all four working spaces. The single working space (SWS) model contains the detailed fluid dynamics. It has seven control volumes in which continuity, energy, and pressure loss effects are simulated. Comparison of the SWS model with experimental data shows reasonable agreement in net power versus speed characteristics for various mean pressure levels in the working space. The four working space (FWS) model was built to observe the behaviour of the whole engine. The drive dynamics and vehicle inertia effects are simulated. To reduce calculation time, only three volumes are used in each working space and the gas temperature are fixed (no energy equation). Comparison of the FWS model predicted power with experimental data shows reasonable agreement. Since all four working spaces are simulated, the unique capabilities of the model are exercised to look at working fluid supply transients, short circuit transients, and piston ring leakage effects.

High salt intake reprioritizes osmolyte and energy metabolism for body fluid conservation.

PubMed

Kitada, Kento; Daub, Steffen; Zhang, Yahua; Klein, Janet D; Nakano, Daisuke; Pedchenko, Tetyana; Lantier, Louise; LaRocque, Lauren M; Marton, Adriana; Neubert, Patrick; Schröder, Agnes; Rakova, Natalia; Jantsch, Jonathan; Dikalova, Anna E; Dikalov, Sergey I; Harrison, David G; Müller, Dominik N; Nishiyama, Akira; Rauh, Manfred; Harris, Raymond C; Luft, Friedrich C; Wassermann, David H; Sands, Jeff M; Titze, Jens

2017-05-01

Natriuretic regulation of extracellular fluid volume homeostasis includes suppression of the renin-angiotensin-aldosterone system, pressure natriuresis, and reduced renal nerve activity, actions that concomitantly increase urinary Na+ excretion and lead to increased urine volume. The resulting natriuresis-driven diuretic water loss is assumed to control the extracellular volume. Here, we have demonstrated that urine concentration, and therefore regulation of water conservation, is an important control system for urine formation and extracellular volume homeostasis in mice and humans across various levels of salt intake. We observed that the renal concentration mechanism couples natriuresis with correspondent renal water reabsorption, limits natriuretic osmotic diuresis, and results in concurrent extracellular volume conservation and concentration of salt excreted into urine. This water-conserving mechanism of dietary salt excretion relies on urea transporter-driven urea recycling by the kidneys and on urea production by liver and skeletal muscle. The energy-intense nature of hepatic and extrahepatic urea osmolyte production for renal water conservation requires reprioritization of energy and substrate metabolism in liver and skeletal muscle, resulting in hepatic ketogenesis and glucocorticoid-driven muscle catabolism, which are prevented by increasing food intake. This natriuretic-ureotelic, water-conserving principle relies on metabolism-driven extracellular volume control and is regulated by concerted liver, muscle, and renal actions.

High salt intake reprioritizes osmolyte and energy metabolism for body fluid conservation

PubMed Central

Kitada, Kento; Daub, Steffen; Zhang, Yahua; Klein, Janet D.; Nakano, Daisuke; Pedchenko, Tetyana; Lantier, Louise; LaRocque, Lauren M.; Marton, Adriana; Neubert, Patrick; Schröder, Agnes; Rakova, Natalia; Jantsch, Jonathan; Dikalova, Anna E.; Dikalov, Sergey I.; Harrison, David G.; Müller, Dominik N.; Nishiyama, Akira; Rauh, Manfred; Harris, Raymond C.; Luft, Friedrich C.; Wasserman, David H.; Sands, Jeff M.

2017-01-01

Natriuretic regulation of extracellular fluid volume homeostasis includes suppression of the renin-angiotensin-aldosterone system, pressure natriuresis, and reduced renal nerve activity, actions that concomitantly increase urinary Na+ excretion and lead to increased urine volume. The resulting natriuresis-driven diuretic water loss is assumed to control the extracellular volume. Here, we have demonstrated that urine concentration, and therefore regulation of water conservation, is an important control system for urine formation and extracellular volume homeostasis in mice and humans across various levels of salt intake. We observed that the renal concentration mechanism couples natriuresis with correspondent renal water reabsorption, limits natriuretic osmotic diuresis, and results in concurrent extracellular volume conservation and concentration of salt excreted into urine. This water-conserving mechanism of dietary salt excretion relies on urea transporter–driven urea recycling by the kidneys and on urea production by liver and skeletal muscle. The energy-intense nature of hepatic and extrahepatic urea osmolyte production for renal water conservation requires reprioritization of energy and substrate metabolism in liver and skeletal muscle, resulting in hepatic ketogenesis and glucocorticoid-driven muscle catabolism, which are prevented by increasing food intake. This natriuretic-ureotelic, water-conserving principle relies on metabolism-driven extracellular volume control and is regulated by concerted liver, muscle, and renal actions. PMID:28414295

Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

NASA Astrophysics Data System (ADS)

Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

2017-08-01

With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

[Estimation of volume of pleural fluid and its impact on spirometrical parameters].

PubMed

Karwat, Krzysztof; Przybyłowski, Tadeusz; Bielicki, Piotr; Hildebrand, Katarzyna; Nowacka-Mazurek, Magdalena; Nasiłowski, Jacek; Rubinsztajn, Renata; Chazan, Ryszarda

2014-03-01

In the course of various diseases, there is an accumulation of fluid in the pleural cavities. Pleural fluid accumulation causes thoracic volume expansion and reduction of volume lungs, leading to formation of restrictive disorders. The aim of the study was to estimate the volume of pleural fluid by ultrasonography and to search for the relationship between pleural fluid volume and spirometrical parameters. The study involved 46 patients (26 men, 20 women) aged 65.7 +/- 14 years with pleural effusions who underwent thoracentesis. Thoracentesis was preceded by ultrasonography of the pleura, spirometry test and plethysmography. The volume of the pleural fluid was calculated with the Goecke' and Schwerk' (GS) or Padykuła (P) equations. The obtained values were compared with the actual evacuated volume. The median volume of the removed pleural fluid was 950 ml. Both underestimated the evacuated volume (the median volume 539 ml for GS and 648 ml for P, respectively). Pleural fluid removal resulted in a statistically significant improvement in VC (increase 0.20 +/- 0.35 ; p < 0.05), FEV1 (increase 0.16 +/- 0.32 l; p < 0.05), TLC (increase 0.30 +/- 0.58 l; p < 0.05) and PEF (0.37 +/- 1 l/s; p < 0.05) CONCLUSIONS: Pleural fluid removal causes a significant improvement in lung function parameters. The analyzed equations for fluid volume calculation do not correlate with the actual volume.

Estimates of fluid and energy balances of Apollo 17

NASA Technical Reports Server (NTRS)

Johnson, P. C.; Leach, C. S.; Rambaut, P. C.

1973-01-01

Fluid and caloric balance has been calculated for the Apollo 17 crew. This included measurement of nitrogen, water, and caloric value of the ingested food and the volume and nitrogen content of the excreted urine and feces. Body composition changes were determined from total body water and extracellular fluid volume differences. The body composition measurements made it possible to divide the weight loss into lean body mass and adipose tissue losses. From this division a caloric equivalent was calculated. These tissue losses indicated that the caloric requirements of the mission were considerably greater than the actual caloric intake. The 3.3 kilo mean loss of body weight represented 1 kilo of lean body mass and 2.3 kilos of adipose tissue. Calculated fluid balance was more positive during the mission than during the control period. These changes are unlike the body composition and fluid balance changes reported in bedrested subjects.

Light Microscopy Module: On-Orbit Microscope Planned for the Fluids Integrated Rack on the International Space Station

NASA Technical Reports Server (NTRS)

Motil, Susan M.

2002-01-01

The Light Microscopy Module (LMM) is planned as a remotely controllable, automated, on-orbit facility, allowing flexible scheduling and control of physical science and biological science experiments within the Fluids Integrated Rack (FIR) on the International Space Station. Initially four fluid physics experiments in the FIR will use the LMM the Constrained Vapor Bubble, the Physics of Hard Spheres Experiment-2, Physics of Colloids in Space-2, and Low Volume Fraction Entropically Driven Colloidal Assembly. The first experiment will investigate heat conductance in microgravity as a function of liquid volume and heat flow rate to determine, in detail, the transport process characteristics in a curved liquid film. The other three experiments will investigate various complementary aspects of the nucleation, growth, structure, and properties of colloidal crystals in microgravity and the effects of micromanipulation upon their properties.

Closed-loop feedback control for microfluidic systems through automated capacitive fluid height sensing.

PubMed

Soenksen, L R; Kassis, T; Noh, M; Griffith, L G; Trumper, D L

2018-03-13

Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1 mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations. Here we present an optimized self-shielded coplanar capacitive sensor design and automated control system to provide submillimeter fluid-height resolution (∼250 μm) and control of small-scale open reservoirs without the need for direct fluid contact. Results from testing and validation of our optimized sensor and system also suggest that accurate fluid height information can be used to robustly characterize, calibrate and dynamically control a range of microfluidic systems with complex pumping mechanisms, even in cell culture conditions. Capacitive sensing technology provides a scalable and cost-effective way to enable continuous monitoring and closed-loop feedback control of fluid volumes in small-scale gravity-dominated wells in a variety of microfluidic applications.

Method and apparatus for controlling fluid flow

DOEpatents

Miller, J.R.

1980-06-27

A method and apparatus for precisely controlling the rate (and hence amount) of fluid flow are given. The controlled flow rate is finely adjustable, can be extremely small (on the order of microliter-atmospheres per second), can be adjusted to zero (flow stopped), and is stable to better than 1% with time. The dead volume of the valve can be made arbitrarily small, in fact essentially zero. The valve employs no wearing mechanical parts (including springs, stems, or seals). The valve is finely adjustable, has a flow rate dynamic range of many decades, can be made compatible with any fluid, and is suitable for incorporation into an open or closed loop servo-control system.

Normal brain tissue volumes after long-term recovery in anorexia and bulimia nervosa.

PubMed

Wagner, Angela; Greer, Phil; Bailer, Ursula F; Frank, Guido K; Henry, Shannan E; Putnam, Karen; Meltzer, Carolyn C; Ziolko, Scott K; Hoge, Jessica; McConaha, Claire; Kaye, Walter H

2006-02-01

Individuals who are ill with anorexia (AN) and bulimia nervosa (BN) often have increased cerebrospinal fluid (CSF) volumes and decreased total gray and white matter volumes. It is unclear whether such disturbances persist after recovery from an eating disorder. Magnetic resonance imaging was performed on 40 women who were long-term recovered (>1 year no binging, purging, or restricting behaviors, normal weight, and menstrual cycles, not on medication) from restricting or binge/purging type AN or BN and 31 healthy control women (CW). Voxel-based morphometry (VBM) was used for data analysis. Recovered AN and BN subgroups were similar to CW in terms of cerebrospinal fluid (CSF) volume as well as total or regional gray or white matter volume. These findings suggest that structural brain abnormalities are reversible in individuals with eating disorders after long-term recovery.

Fluid balance, glomerular filtration rate, and urine output in dogs anesthetized for an orthopedic surgical procedure.

PubMed

Boscan, Pedro; Pypendop, Bruno H; Siao, Kristine T; Francey, Thierry; Dowers, Kristy; Cowgill, Larry; Ilkiw, Jan E

2010-05-01

To determine fluid retention, glomerular filtration rate, and urine output in dogs anesthetized for a surgical orthopedic procedure. 23 dogs treated with a tibial plateau leveling osteotomy. 12 dogs were used as a control group. Cardiac output was measured in 5 dogs, and 6 dogs received carprofen for at least 14 days. Dogs received oxymorphone, atropine, propofol, and isoflurane for anesthesia (duration, 4 hours). Urine and blood samples were obtained for analysis every 30 minutes. Lactated Ringer's solution was administered at 10 mL/kg/h. Urine output was measured and glomerular filtration rate was estimated. Fluid retention was measured by use of body weight, fluid balance, and bioimpedance spectroscopy. No difference was found among control, cardiac output, or carprofen groups, so data were combined. Median urine output and glomerular filtration rate were 0.46 mL/kg/h and 1.84 mL/kg/min. Dogs retained a large amount of fluids during anesthesia, as indicated by increased body weight, positive fluid balance, increased total body water volume, and increased extracellular fluid volume. The PCV, total protein concentration, and esophageal temperature decreased in a linear manner. Dogs anesthetized for a tibial plateau leveling osteotomy retained a large amount of fluids, had low urinary output, and had decreased PCV, total protein concentration, and esophageal temperature. Evaluation of urine output alone in anesthetized dogs may not be an adequate indicator of fluid balance.

[Perioperative fluid therapy for surgical patients with chronic kidney disease].

PubMed

Iijima, Takehiko

2013-11-01

Chronic kidney disease (CKD) often accompanies cardiovascular complications, causing postoperative morbidity and even mortality. Since fluid and electrolyte homeostasis is deregulated in CKD patients, fluid therapy itself may cause postoperative morbidity. Recent studies have shown that forced diuresis through fluid overload offers no renoprotective effect and instead has harmful consequences. Fluid overload should be avoided, and the volume load should be used as the rationale for controlling hemodynamics. The emerging concept of a "zero-fluid balance policy" may be beneficial even for CKD patients. Hydroxyethylstarch might not be preferentially used for CKD patients. Hydroxyethylstarch is not contraindicated for CKD patients except in cases with long-term accumulation caused by increased vascular permeability, such as cases with sepsis, as long as an efficient volume expansion is beneficial to the patient. The regulation of renal function through the endocrine system (i.e., renin-angiotensin-aldosterone and vasopressin) is a key target for protecting the kidney in CKD. The recent development of a receptor blocker targeting these endocrine systems may be beneficial for correcting the fluid balance caused by excess intraoperative fluid therapy. The main issue for fluid therapy in surgical CKD patients may not be the quantity of fluid, but rational intervention affecting the endocrine system.

Engine lubrication circuit including two pumps

DOEpatents

Lane, William H.

2006-10-03

A lubrication pump coupled to the engine is sized such that the it can supply the engine with a predetermined flow volume as soon as the engine reaches a peak torque engine speed. In engines that operate predominately at speeds above the peak torque engine speed, the lubrication pump is often producing lubrication fluid in excess of the predetermined flow volume that is bypassed back to a lubrication fluid source. This arguably results in wasted power. In order to more efficiently lubricate an engine, a lubrication circuit includes a lubrication pump and a variable delivery pump. The lubrication pump is operably coupled to the engine, and the variable delivery pump is in communication with a pump output controller that is operable to vary a lubrication fluid output from the variable delivery pump as a function of at least one of engine speed and lubrication flow volume or system pressure. Thus, the lubrication pump can be sized to produce the predetermined flow volume at a speed range at which the engine predominately operates while the variable delivery pump can supplement lubrication fluid delivery from the lubrication pump at engine speeds below the predominant engine speed range.

The "chloride theory", a unifying hypothesis for renal handling and body fluid distribution in heart failure pathophysiology.

PubMed

Kataoka, Hajime

2017-07-01

Body fluid volume regulation is a complex process involving the interaction of various afferent (sensory) and neurohumoral efferent (effector) mechanisms. Historically, most studies focused on the body fluid dynamics in heart failure (HF) status through control of the balance of sodium, potassium, and water in the body, and maintaining arterial circulatory integrity is central to a unifying hypothesis of body fluid regulation in HF pathophysiology. The pathophysiologic background of the biochemical determinants of vascular volume in HF status, however, has not been known. I recently demonstrated that changes in vascular and red blood cell volumes are independently associated with the serum chloride concentration, but not the serum sodium concentration, during worsening HF and its recovery. Based on these observations and the established central role of chloride in the renin-angiotensin-aldosterone system, I propose a unifying hypothesis of the "chloride theory" for HF pathophysiology, which states that changes in the serum chloride concentration are the primary determinant of changes in plasma volume and the renin-angiotensin-aldosterone system under worsening HF and therapeutic resolution of worsening HF. Copyright © 2017 Elsevier Ltd. All rights reserved.

International Congress of Fluid Mechanics, 3rd, Cairo, Egypt, Jan. 2-4, 1990, Proceedings. Volumes 1, 2, 3, & 4

NASA Astrophysics Data System (ADS)

Nayfeh, A. H.; Mobarak, A.; Rayan, M. Abou

This conference presents papers in the fields of flow separation, unsteady aerodynamics, fluid machinery, boundary-layer control and stability, grid generation, vorticity dominated flows, and turbomachinery. Also considered are propulsion, waves and sound, rotor aerodynamics, computational fluid dynamics, Euler and Navier-Stokes equations, cavitation, mixing and shear layers, mixing layers and turbulent flows, and fluid machinery and two-phase flows. Also addressed are supersonic and reacting flows, turbulent flows, and thermofluids.

Fluid imbalance

MedlinePlus

... up in the body. This is called fluid overload (volume overload). This can lead to edema (excess fluid in ... Water imbalance; Fluid imbalance - dehydration; Fluid buildup; Fluid overload; Volume overload; Loss of fluids; Edema - fluid imbalance; ...

A randomized controlled trial of the effect of intrapartum intravenous fluid management on breastfed newborn weight loss.

PubMed

Watson, Jo; Hodnett, Ellen; Armson, B Anthony; Davies, Barbara; Watt-Watson, Judy

2012-01-01

To determine the effect of conservative versus usual intrapartum intravenous (IV) fluid management for low-risk women receiving epidural analgesia on weight loss in breastfed newborns. A randomized controlled trial. A tertiary perinatal center in a large urban setting. Women experiencing uncomplicated pregnancies who planned to have epidural analgesia and to breastfeed. Healthy pregnant women were randomized to receive an IV epidural preload volume of <500 mLs continuing at an hourly rate of 75-100 mL/h (conservative care) or an epidural preload volume of ≥500 mLs and an hourly rate >125 mL/h (usual care). The primary study outcome was breastfed newborn weight loss >7% prior to hospital discharge. Secondary study outcomes included breastfeeding exclusivity, referral to outpatient breastfeeding clinic support, and delayed discharge. Other outcomes were admission to the neonatal intensive care unit and cord blood pH <7.25. Two hundred women participated (100 in the conservative care and 100 in the usual care groups). Forty-eight of 100 infants in the usual care group and 44 of the 100 infants in the conservative care group lost >7% of their birth weight prior to discharge, p < 0.52 RR 0.92 [0.68-1.24]. A policy of restricted IV fluids did not affect newborn weight loss. Women and their care providers should be reassured that the volumes of IV fluid <2500 mLs are unlikely to have a clinically meaningful effect on breastfed newborn weight loss >7%. Exploratory analyses suggest that breastfed newborn weight loss increases when intrapartum volumes infused are >2500 mLs. Care providers are encouraged to consider volumes of IV fluid infused intrapartum as a factor that may have contributed to early newborn weight loss in the first 48 h of life. © 2012 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

Fluid-loading solutions and plasma volume: Astro-ade and salt tablets with water

NASA Technical Reports Server (NTRS)

Fortney, Suzanne M.; Seinmann, Laura; Young, Joan A.; Hoskin, Cherylynn N.; Barrows, Linda H.

1994-01-01

Fluid loading with salt and water is a countermeasure used after space flight to restore body fluids. However, gastrointestinal side effects have been frequently reported in persons taking similar quantities of salt and water in ground-based studies. The effectiveness of the Shuttle fluid-loading countermeasure (8 gms salt, 0.97 liters of water) was compared to Astro-ade (an isotonic electrolyte solution), to maintain plasma volume (PV) during 4.5 hrs of resting fluid restriction. Three groups of healthy men (n=6) were studied: a Control Group (no drinking), an Astro-ade Group, and a Salt Tablet Group. Changes in PV after drinking were calculated from hematocrit and hemoglobin values. Both the Salt Tablet and Astro-ade Groups maintained PV at 2-3 hours after ingestion compared to the Control Group, which had a 6 percent decline. Side effects (thirst, stomach cramping, and diarrhea) were noted in at least one subject in both the Astro-ade and Salt Tablet Groups. Nausea and vomiting were reported in one subject in the Salt Tablet Group. It was concluded that Astro-ade may be offered as an alternate fluid-loading countermeasure but further work is needed to develop a solution that is more palatable and has fewer side effects.

Uncontrolled Hemorrhage Differs From Volume- or Pressure-Matched Controlled Hemorrhage in Swine

DTIC Science & Technology

2007-10-01

differences between these models, we evaluated the relationship between blood volume loss and blood pressure in controlled versus uncontrolled hemorrhage...aortotomy; (2) group P, controlled hemorrhage matched to the blood pressure profile of group U; or (3) group V, controlled hemorrhage matched to the...hemorrhage and received no fluid resuscitation. Group U resulted in a blood loss of 17.6 T 0.7 mL kgj1 and a reduction in blood pressure to 28 T 3 mmHg at

Precise nanoliter fluid handling system with integrated high-speed flow sensor.

PubMed

Haber, Carsten; Boillat, Marc; van der Schoot, Bart

2005-04-01

A system for accurate low-volume delivery of liquids in the micro- to nanoliter range makes use of an integrated miniature flow sensor as part of an intelligent feedback control loop driving a micro-solenoid valve. The flow sensor is hydraulically connected with the pressurized system liquid in the dispensing channel and located downstream from the pressure source, above the solenoid valve. The sensor operates in a differential mode and responds in real-time to the internal flow-pulse resulting from the brief opening interval of the solenoid valve leading to a rapid ejection of a fluid droplet. The integral of the flow-pulse delivered by the sensor is directly proportional to the volume of the ejected droplet from the nozzle. The quantitative information is utilized to provide active control of the effectively dispensed or aspirated volume by adjusting the solenoid valve accordingly. This process significantly enhances the precision of the fluid delivery. The system furthermore compensates automatically for any changes in the viscosity of the dispensed liquid. The data delivered by the flow sensor can be saved and backtracked in order to confirm and validate the aspiration and dispensing process in its entirety. The collected dispense information can be used for quality control assessments and automatically be made part of an electronic record.

Study on Controls of Fluids in Nanochannel via Hybrid Surface

NASA Astrophysics Data System (ADS)

Ye, Ziran

This thesis contributes to the investigation of controls of nanofluidic fluids by utilizing hybrid surface patterns in nanochannel. Nanofluidics is a core and interdisciplinary research field which manipulates, controls and analyzes fluids in nanoscale and develop potential bio/chemical applications. This thesis studies the surface-induced phenomena in nanofluidics, we use surface decoration on nanochannel walls to investigate the influences on fluid motion and further explore the fundamental physical principle of this behavior. To begin with, we designed and fabricated the nanofluidic mixer for the first time, which comprised hybrid surface patterns with different wettabilities on both top and bottom walls of nanochannel. Although microfluidic mixers have been intensively investigated, nanofluidic mixer has never been reported. Without any inside geometric structure of nanochannel, the mixing phenomenon can be achieved by the surface patterns and the mixing length can be significantly shortened comparing with micromixer. We attribute this achievement to the chaotic flows of two fluids induced by the patterned surface. The surface-related phenomena may not be so prominent on large scale, however, it is pronounced when the scale shrinks down to nanometer due to the large surface-to-volume ratio in nanochannel. In the second part of this work, based on the technology of nanofabrication and similar principle, we built up another novel method to control the speed of capillary flow in nanochannel in a quantitative manner. Surface patterns were fabricated on the nanochannel walls to slow down the capillary flow. The flow speed can be precisely controlled by modifying hydrophobicity ratio. Under the extreme surface-to-volume ratio in nanochannel, the significant surface effect on the fluid effectively reduced the speed of capillary flow without any external energy source and equipment. Such approach may be adopted for a wide variety of nanofluidicsbased biochemical analysis systems.

Influence of fluid and volume state on PaO2 oscillations in mechanically ventilated pigs.

PubMed

Bodenstein, Marc; Bierschock, Stephan; Boehme, Stefan; Wang, Hemei; Vogt, Andreas; Kwiecien, Robert; David, Matthias; Markstaller, Klaus

2013-03-01

Varying pulmonary shunt fractions during the respiratory cycle cause oxygen oscillations during mechanical ventilation. In artificially damaged lungs, cyclical recruitment of atelectasis is responsible for varying shunt according to published evidence. We introduce a complimentary hypothesis that cyclically varying shunt in healthy lungs is caused by cyclical redistribution of pulmonary perfusion. Administration of crystalloid or colloid infusions would decrease oxygen oscillations if our hypothesis was right. Therefore, n=14 mechanically ventilated healthy pigs were investigated in 2 groups: crystalloid (fluid) versus no-fluid administration. Additional volume interventions (colloid infusion, blood withdrawal) were carried out in each pig. Intra-aortal PaO2 oscillations were recorded using fluorescence quenching technique. Phase shift of oxygen oscillations during altered inspiratory to expiratory (I:E) ventilation ratio and electrical impedance tomography (EIT) served as control methods to exclude that recruitment of atelectasis is responsible for oxygen oscillations. In hypovolemia relevant oxygen oscillations could be recorded. Fluid and volume state changed PaO2 oscillations according to our hypothesis. Fluid administration led to a mean decline of 105.3 mmHg of the PaO2 oscillations amplitude (P<0.001). The difference of the amplitudes between colloid administration and blood withdrawal was 62.4 mmHg in pigs not having received fluids (P=0.0059). Fluid and volume state also changed the oscillation phase during altered I:E ratio. EIT excluded changes of regional ventilation (i.e., recruitment of atelectasis) to be responsible for these oscillations. In healthy pigs, cyclical redistribution of pulmonary perfusion can explain the size of respiratory-dependent PaO2 oscillations.

An integrated algorithm for hypersonic fluid-thermal-structural numerical simulation

NASA Astrophysics Data System (ADS)

Li, Jia-Wei; Wang, Jiang-Feng

2018-05-01

In this paper, a fluid-structural-thermal integrated method is presented based on finite volume method. A unified integral equations system is developed as the control equations for physical process of aero-heating and structural heat transfer. The whole physical field is discretized by using an up-wind finite volume method. To demonstrate its capability, the numerical simulation of Mach 6.47 flow over stainless steel cylinder shows a good agreement with measured values, and this method dynamically simulates the objective physical processes. Thus, the integrated algorithm proves to be efficient and reliable.

How do sock ply changes affect residual-limb fluid volume in people with transtibial amputation?

PubMed

Sanders, Joan E; Harrison, Daniel S; Allyn, Katheryn J; Myers, Timothy R; Ciol, Marcia A; Tsai, Elaine C

2012-01-01

The purpose of this research was to investigate the influence of sock addition and removal on residual-limb fluid volume in people using prosthetic limbs. We used bioimpedance analysis to measure residual-limb extracellular fluid volume on 28 transtibial amputee subjects during 30 min test sessions. Upon addition of a one-ply polyester sock, residual-limb fluid volume changes ranged from -4.0% to 0.8% (mean -0.9 +/- 1.3%) of the initial limb fluid volume. Changes for sock removal ranged from -1.2% to 2.8% (mean 0.5 +/- 0.8%). Subjects who reduced in fluid volume with both addition and removal of a sock and subjects with high positive ratios between the fluid-volume loss upon sock addition and gain upon sock removal (high add/remove [AR] ratios) tended to have arterial disease, were obese, and were smokers. Subjects with low positive AR ratios, subjects who increased in fluid volume both with sock addition and removal, and a single subject who increased in fluid volume with sock addition and decreased with sock removal tended to be nonsmokers and either individuals in good health without complications or individuals without arterial problems. Results are relevant for the anticipation of limb volume changes during prosthetic fitting and toward the design of adjustable-socket technologies.

Acoustic auditing as a real-time, non-invasive quality control process for both source and assay plates.

PubMed

Olechno, Joseph; Ellson, Richard; Browning, Brent; Stearns, Richard; Mutz, Mitchell; Travis, Michael; Qureshi, Shehrzad; Shieh, Jean

2005-08-01

Acoustic auditing is a non-destructive, non-invasive technique to monitor the composition and volume of fluids in open or sealed microplates and storage tubes. When acoustic energy encounters an interface between two materials, some of the energy passes through the interface, while the remainder is reflected. Acoustic energy applied to the bottom of a multi-well plate or a storage tube is reflected by the fluid contents of the microplate or tube. The amplitude of these reflections or echoes correlates directly with properties of the fluid, including the speed of sound and the concentration of water in the fluid. Once the speed of sound in the solution is known from the analysis of these echoes, it is easy to determine the depth of liquid and, thereby, the volume by monitoring how long it takes for sound energy to reflect off the fluid meniscus. This technique is rapid (>100,000 samples per day), precise (<1% coefficient of variation for hydration measurements, <4% coefficient of variation for volume measurements), and robust. It does not require uncapping tubes or unsealing or unlidding microplates. The sound energy is extremely gentle and has no deleterious impact upon the fluid or compounds dissolved in it.

Sample preparation system for microfluidic applications

DOEpatents

Mosier, Bruce P [San Francisco, CA; Crocker, Robert W [Fremont, CA; Patel, Kamlesh D [Dublin, CA; Harnett, Cindy K [Livermore, CA

2007-05-08

An apparatus that couples automated injection with flow feedback to provide nanoliter accuracy in controlling microliter volumes. The apparatus comprises generally a source of hydraulic fluid pressure, a fluid isolator joined to the outlet of the hydraulic pressure source and a flow sensor to provide pressure-driven analyte metering. For operation generally and particularly in microfluidic systems the hydraulic pressure source is typically an electrokinetic (EK) pump that incorporates gasless electrodes. The apparatus is capable of metering sub-microliter volumes at flowrates of 1 100 .mu.L/min into microsystem load pressures of up to 1000 50 psi, respectively. Flowrates can be specified within 0.5 .mu.L/min and volumes as small as 80 nL can be metered.

Chamber for the optical manipulation of microscopic particles

DOEpatents

Buican, Tudor N.; Upham, Bryan D.

1992-01-01

A particle control chamber enables experiments to be carried out on biological cells and the like using a laser system to trap and manipulate the particles. A manipulation chamber provides a plurality of inlet and outlet ports for the particles and for fluids used to control or to contact the particles. A central manipulation area is optically accessible by the laser and includes first enlarged volumes for containing a selected number of particles for experimentation. A number of first enlarged volumes are connected by flow channels through second enlarged volumes. The second enlarged volumes act as bubble valves for controlling the interconnections between the first enlarged volumes. Electrode surfaces may be applied above the first enlarged volumes to enable experimentation using the application of electric fields within the first enlarged volumes. A variety of chemical and environmental conditions may be established within individual first enlarged volumes to enable experimental conditions for small scale cellular interactions.

Molecular representation of molar domain (volume), evolution equations, and linear constitutive relations for volume transport.

PubMed

Eu, Byung Chan

2008-09-07

In the traditional theories of irreversible thermodynamics and fluid mechanics, the specific volume and molar volume have been interchangeably used for pure fluids, but in this work we show that they should be distinguished from each other and given distinctive statistical mechanical representations. In this paper, we present a general formula for the statistical mechanical representation of molecular domain (volume or space) by using the Voronoi volume and its mean value that may be regarded as molar domain (volume) and also the statistical mechanical representation of volume flux. By using their statistical mechanical formulas, the evolution equations of volume transport are derived from the generalized Boltzmann equation of fluids. Approximate solutions of the evolution equations of volume transport provides kinetic theory formulas for the molecular domain, the constitutive equations for molar domain (volume) and volume flux, and the dissipation of energy associated with volume transport. Together with the constitutive equation for the mean velocity of the fluid obtained in a previous paper, the evolution equations for volume transport not only shed a fresh light on, and insight into, irreversible phenomena in fluids but also can be applied to study fluid flow problems in a manner hitherto unavailable in fluid dynamics and irreversible thermodynamics. Their roles in the generalized hydrodynamics will be considered in the sequel.

Waterflood control system for maximizing total oil recovery

DOEpatents

Patzek, Tadeusz Wiktor; Silin, Dimitriy Borisovic; De, Asoke Kumar

2005-06-07

A control system and method for determining optimal fluid injection pressure is based upon a model of a growing hydrofracture due to waterflood injection pressure. This model is used to develop a control system optimizing the injection pressure by using a prescribed injection goal coupled with the historical times, pressures, and volume of injected fluid at a single well. In this control method, the historical data is used to derive two major flow components: the transitional component, where cumulative injection volume is scaled as the square root of time, and a steady-state breakthrough component, which scales linearly with respect to time. These components provide diagnostic information and allow for the prevention of rapid fracture growth and associated massive water break through that is an important part of a successful waterflood, thereby extending the life of both injection and associated production wells in waterflood secondary oil recovery operations.

Waterflood control system for maximizing total oil recovery

DOEpatents

Patzek, Tadeusz Wiktor [Oakland, CA; Silin, Dimitriy Borisovich [Pleasant Hill, CA; De, Asoke Kumar [San Jose, CA

2007-07-24

A control system and method for determining optimal fluid injection pressure is based upon a model of a growing hydrofracture due to waterflood injection pressure. This model is used to develop a control system optimizing the injection pressure by using a prescribed injection goal coupled with the historical times, pressures, and volume of injected fluid at a single well. In this control method, the historical data is used to derive two major flow components: the transitional component, where cumulative injection volume is scaled as the square root of time, and a steady-state breakthrough component, which scales linearly with respect to time. These components provide diagnostic information and allow for the prevention of rapid fracture growth and associated massive water break through that is an important part of a successful waterflood, thereby extending the life of both injection and associated production wells in waterflood secondary oil recovery operations.

Regulation of body fluid volume and electrolyte concentrations in spaceflight.

PubMed

Smith, S M; Krauhs, J M; Leach, C S

1997-01-01

Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian rhythms. Atrial natriuretic peptide does not seem to play an important role in the control of natriuresis during spaceflight. Inflight activity of the sympathetic nervous system, assessed by measuring catecholamines and their metabolites and precursors in body fluids, generally seems to be no greater than on Earth, but this system is usually activated at landing. Collaborative experiments on the Mir and the International Space Station should provide more of the data needed from long-term flights, and perhaps help to resolve some of the discrepancies between U.S. and Russian data. The use of alternative methods that are easier to execute during spaceflight, such as collection of saliva instead of blood and urine, should permit more thorough study of circadian rhythms and rapid hormone changes in weightlessness. More investigations of dietary intake of fluid and electrolytes must be performed to understand regulatory processes. Additional hormones that may participate in these processes, such as other natriuretic hormones, should be determined during and after spaceflight. Alterations in body fluid volume and blood electrolyte concentrations during spaceflight have important consequences for readaptation to the 1-G environment. The current assessment of fluid and electrolyte status during weightlessness and at landing and our still incomplete understanding of the processes of adaptation to weightlessness and readaptation to Earth's gravity have resulted in the development of countermeasures that are only partly successful in reducing the postflight orthostatic intolerance experienced by astronauts and cosmonauts. More complete knowledge of these processes can be expected to produce countermeasures that are even more successful, as well as expand our comprehension of the range of adaptability of human physiologic processes.

Regulation of body fluid volume and electrolyte concentrations in spaceflight

NASA Technical Reports Server (NTRS)

Smith, S. M.; Krauhs, J. M.; Leach, C. S.

1997-01-01

Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian rhythms. Atrial natriuretic peptide does not seem to play an important role in the control of natriuresis during spaceflight. Inflight activity of the sympathetic nervous system, assessed by measuring catecholamines and their metabolites and precursors in body fluids, generally seems to be no greater than on Earth, but this system is usually activated at landing. Collaborative experiments on the Mir and the International Space Station should provide more of the data needed from long-term flights, and perhaps help to resolve some of the discrepancies between U.S. and Russian data. The use of alternative methods that are easier to execute during spaceflight, such as collection of saliva instead of blood and urine, should permit more thorough study of circadian rhythms and rapid hormone changes in weightlessness. More investigations of dietary intake of fluid and electrolytes must be performed to understand regulatory processes. Additional hormones that may participate in these processes, such as other natriuretic hormones, should be determined during and after spaceflight. Alterations in body fluid volume and blood electrolyte concentrations during spaceflight have important consequences for readaptation to the 1-G environment. The current assessment of fluid and electrolyte status during weightlessness and at landing and our still incomplete understanding of the processes of adaptation to weightlessness and readaptation to Earth's gravity have resulted in the development of countermeasures that are only partly successful in reducing the postflight orthostatic intolerance experienced by astronauts and cosmonauts. More complete knowledge of these processes can be expected to produce countermeasures that are even more successful, as well as expand our comprehension of the range of adaptability of human physiologic processes.

Structural magnetic resonance imaging in patients with first-episode schizophrenia, psychotic and severe non-psychotic depression and healthy controls. Results of the schizophrenia and affective psychoses (SAP) project.

PubMed

Salokangas, R K R; Cannon, T; Van Erp, T; Ilonen, T; Taiminen, T; Karlsson, H; Lauerma, H; Leinonen, K M; Wallenius, E; Kaljonen, A; Syvälahti, E; Vilkman, H; Alanen, A; Hietala, J

2002-09-01

Structural brain abnormalities are prevalent in patients with schizophrenia and affective disorders. To study how regional brain volumes and their ratios differ between patients with schizophrenia, psychotic depression, severe non-psychotic depression and healthy controls. Magnetic resonance imaging scans of the brain on first-episode patients and on healthy controls. Patients with schizophrenia had a smaller left frontal grey matter volume than the other three groups. Patients with psychotic depression had larger ventricular and posterior sulcal cerebrospinal fluid (CSF) volumes than controls. Patients with depression had larger white matter volumes than the other patients. Left frontal lobe, especially its grey matter volume, seems to be specifically reduced in first-episode schizophrenia. Enlarged cerebral ventricles and sulcal CSF volumes are prevalent in psychotic depression. Preserved or expanded white matter is typical of non-psychotic depression.

Blood volume-monitored regulation of ultrafiltration in fluid-overloaded hemodialysis patients: study protocol for a randomized controlled trial.

PubMed

Hecking, Manfred; Antlanger, Marlies; Winnicki, Wolfgang; Reiter, Thomas; Werzowa, Johannes; Haidinger, Michael; Weichhart, Thomas; Polaschegg, Hans-Dietrich; Josten, Peter; Exner, Isabella; Lorenz-Turnheim, Katharina; Eigner, Manfred; Paul, Gernot; Klauser-Braun, Renate; Hörl, Walter H; Sunder-Plassmann, Gere; Säemann, Marcus D

2012-06-08

Data generated with the body composition monitor (BCM, Fresenius) show, based on bioimpedance technology, that chronic fluid overload in hemodialysis patients is associated with poor survival. However, removing excess fluid by lowering dry weight can be accompanied by intradialytic and postdialytic complications. Here, we aim at testing the hypothesis that, in comparison to conventional hemodialysis, blood volume-monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) will decrease complications when ultrafiltration volumes are systematically increased in fluid-overloaded hemodialysis patients. BCM measurements yield results on fluid overload (in liters), relative to extracellular water (ECW). In this prospective, multicenter, triple-arm, parallel-group, crossover, randomized, controlled clinical trial, we use BCM measurements, routinely introduced in our three maintenance hemodialysis centers shortly prior to the start of the study, to recruit sixty hemodialysis patients with fluid overload (defined as ≥15% ECW). Patients are randomized 1:1:1 into UCR, UTR and conventional hemodialysis groups. BCM-determined, 'final' dry weight is set to normohydration weight -7% of ECW postdialysis, and reached by reducing the previous dry weight, in steps of 0.1 kg per 10 kg body weight, during 12 hemodialysis sessions (one study phase). In case of intradialytic complications, dry weight reduction is decreased, according to a prespecified algorithm. A comparison of intra- and post-dialytic complications among study groups constitutes the primary endpoint. In addition, we will assess relative weight reduction, changes in residual renal function, quality of life measures, and predialysis levels of various laboratory parameters including C-reactive protein, troponin T, and N-terminal pro-B-type natriuretic peptide, before and after the first study phase (secondary outcome parameters). Patients are not requested to revert to their initial degree of fluid overload after each study phase. Therefore, the crossover design of the present study merely serves the purpose of secondary endpoint evaluation, for example to determine patient choice of treatment modality. Previous studies on blood volume monitoring have yielded inconsistent results. Since we include only patients with BCM-determined fluid overload, we expect a benefit for all study participants, due to strict fluid management, which decreases the mortality risk of hemodialysis patients. ClinicalTrials.gov, NCT01416753.

Blood volume-monitored regulation of ultrafiltration in fluid-overloaded hemodialysis patients: study protocol for a randomized controlled trial

PubMed Central

2012-01-01

Background Data generated with the body composition monitor (BCM, Fresenius) show, based on bioimpedance technology, that chronic fluid overload in hemodialysis patients is associated with poor survival. However, removing excess fluid by lowering dry weight can be accompanied by intradialytic and postdialytic complications. Here, we aim at testing the hypothesis that, in comparison to conventional hemodialysis, blood volume-monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) will decrease complications when ultrafiltration volumes are systematically increased in fluid-overloaded hemodialysis patients. Methods/design BCM measurements yield results on fluid overload (in liters), relative to extracellular water (ECW). In this prospective, multicenter, triple-arm, parallel-group, crossover, randomized, controlled clinical trial, we use BCM measurements, routinely introduced in our three maintenance hemodialysis centers shortly prior to the start of the study, to recruit sixty hemodialysis patients with fluid overload (defined as ≥15% ECW). Patients are randomized 1:1:1 into UCR, UTR and conventional hemodialysis groups. BCM-determined, ‘final’ dry weight is set to normohydration weight −7% of ECW postdialysis, and reached by reducing the previous dry weight, in steps of 0.1 kg per 10 kg body weight, during 12 hemodialysis sessions (one study phase). In case of intradialytic complications, dry weight reduction is decreased, according to a prespecified algorithm. A comparison of intra- and post-dialytic complications among study groups constitutes the primary endpoint. In addition, we will assess relative weight reduction, changes in residual renal function, quality of life measures, and predialysis levels of various laboratory parameters including C-reactive protein, troponin T, and N-terminal pro-B-type natriuretic peptide, before and after the first study phase (secondary outcome parameters). Discussion Patients are not requested to revert to their initial degree of fluid overload after each study phase. Therefore, the crossover design of the present study merely serves the purpose of secondary endpoint evaluation, for example to determine patient choice of treatment modality. Previous studies on blood volume monitoring have yielded inconsistent results. Since we include only patients with BCM-determined fluid overload, we expect a benefit for all study participants, due to strict fluid management, which decreases the mortality risk of hemodialysis patients. Trial registration ClinicalTrials.gov, NCT01416753 PMID:22682149

Effect of pre-donation fluid intake on fluid shift from interstitial to intravascular compartment in blood donors.

PubMed

Deepika, Chenna; Murugesan, Mohandoss; Shastry, Shamee

2018-02-01

Fluid shifts from interstitial to intravascular space during blood donation helps in compensating the lost blood volume. We aimed to determine the volume of fluid shift following donation in donors with and without pre-donation fluid intake. We studied the fluid shift in 325 blood donors prospectively. Donors were divided in groups- with no fluid intake (GI) and either water (GII) or oral rehydrating fluids (GIII) before donation. Fluid shift following donation was calculated based on the difference between the pre and post donation blood volume. The influence of oral fluid intake, age, gender and body mass index (BMI) on volume of fluid shift was analyzed. The fluid shift was significant between donors without fluids (GI: 127 ± 81 ml) and donors with fluid intake (GII & III: 96 ± 45 ml) (p < 0.05). The difference was not significant between donors with water intake (GII: 106 ± 52 ml) and oral rehydrating fluid intake (GIII: 87 ± 41 ml). The shifted fluid volume increased with increasing BMI and decreased with increasing age in females. The fluid shift increased in females than in males. The age, gender, BMI and VVR did not significantly contribute to the volume of fluid shift following donation. As per our observation, the oral fluids before donation might not contribute to increase in fluid shift in blood donors after donation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mild hypothermia attenuates changes in respiratory system mechanics and modifies cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation.

PubMed

Dostál, P; Senkeřík, M; Pařízková, R; Bareš, D; Zivný, P; Zivná, H; Cerný, V

2010-01-01

Hypothermia was shown to attenuate ventilator-induced lung injury due to large tidal volumes. It is unclear if the protective effect of hypothermia is maintained under less injurious mechanical ventilation in animals without previous lung injury. Tracheostomized rats were randomly allocated to non-ventilated group (group C) or ventilated groups of normothermia (group N) and mild hypothermia (group H). After two hours of mechanical ventilation with inspiratory fraction of oxygen 1.0, respiratory rate 60 min(-1), tidal volume 10 ml x kg(-1), positive end-expiratory pressure (PEEP) 2 cm H2O or immediately after tracheostomy in non-ventilated animals inspiratory pressures were recorded, rats were sacrificed, pressure-volume (PV) curve of respiratory system constructed, bronchoalveolar lavage (BAL) fluid and aortic blood samples obtained. Group N animals exhibited a higher rise in peak inspiratory pressures in comparison to group H animals. Shift of the PV curve to right, higher total protein and interleukin-6 levels in BAL fluid were observed in normothermia animals in comparison with hypothermia animals and non-ventilated controls. Tumor necrosis factor-alpha was lower in the hypothermia group in comparison with normothermia and non-ventilated groups. Mild hypothermia attenuated changes in respiratory system mechanics and modified cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation in animals without previous lung injury.

Bioimpedance Spectroscopy for Assessment of Volume Status in Patients before and after General Anaesthesia

PubMed Central

Ernstbrunner, Matthäus; Kostner, Lisa; Kimberger, Oliver; Wabel, Peter; Säemann, Marcus; Markstaller, Klaus; Fleischmann, Edith; Kabon, Barbara; Hecking, Manfred

2014-01-01

Background Technically assisted assessment of volume status before surgery may be useful to direct intraoperative fluid administration. We therefore tested a recently developed whole-body bioimpedance spectroscopy device to determine pre- to postoperative fluid distribution. Methods Using a three-compartment physiologic tissue model, the body composition monitor (BCM, Fresenius Medical Care, Germany) measures total body fluid volume, extracellular volume, intracellular volume and fluid overload as surplus or deficit of ‘normal’ extracellular volume. BCM-measurements were performed before and after standardized general anaesthesia for gynaecological procedures (laparotomies, laparoscopies and vaginal surgeries). BCM results were blinded to the attending anaesthesiologist and data analysed using the 2-sided, paired Student’s t-test and multiple linear regression. Results In 71 females aged 45±15 years with body weight 67±13 kg and duration of anaesthesia 154±68 min, pre- to postoperative fluid overload increased from −0.7±1.1 L to 0.1±1.0 L, corresponding to −5.1±7.5% and 0.8±6.7% of normal extracellular volume, respectively (both p<0.001), after patients had received 1.9±0.9 L intravenous crystalloid fluid. Perioperative urinary excretion was 0.4±0.3 L. The increase in extracellular volume was paralleled by an increase in total body fluid volume, while intracellular volume increased only slightly and without reaching statistical significance (p = 0.15). Net perioperative fluid balance (administered fluid volume minus urinary excretion) was significantly associated with change in extracellular volume (r2 = 0.65), but was not associated with change in intracellular volume (r2 = 0.01). Conclusions Routine intraoperative fluid administration results in a significant, and clinically meaningful increase in the extracellular compartment. BCM-measurements yielded plausible results and may become useful to guide intraoperative fluid therapy in future studies. PMID:25360698

A model for plasma volume changes during short duration spaceflight

NASA Technical Reports Server (NTRS)

Davis, John E.

1989-01-01

It is well established that plasma volume decreases during spaceflight and simulated weightlessness (bedrest). The decrement in plasma volume is thought to contribute to the orthostatic intolerance that has been observed in some crew members following spaceflight. To date, no studies have evaluated the effectiveness of fluid countermeasures of varying osmolality in the restoration of plasma volume and orthostatic tolerance in a controlled study. The overall objectives of this project were to: (1) provide a model that would rapidly and safely produce a fluid loss comparable to that which occurs during short duration spaceflight; and (2) design a study that would determine the optimal drink solution to restore orthostatic tolerance and describe the mechanism(s) whereby orthostatic tolerance is restored. In summary, Lasix can be used as a way of simulating the plasma volume changes that occur during short duration spaceflight. The total loss of plasma is comparable to spaceflight. Lasix is fast acting, and has relatively few side effects. The present design for evaluating the optimal fluid countermeasures will have important implications in restoring orthostatic tolerance and function in the latter stages of spaceflight when it is essential for safe operation of the spacecraft.

Preoperative oral carbohydrate administration to ASA III-IV patients undergoing elective cardiac surgery.

PubMed

Breuer, Jan-P; von Dossow, Vera; von Heymann, Christian; Griesbach, Markus; von Schickfus, Michael; Mackh, Elise; Hacker, Cornelia; Elgeti, Ulrike; Konertz, Wolfgang; Wernecke, Klaus-D; Spies, Claudia D

2006-11-01

In this study we investigated the effects of preoperative oral carbohydrate administration on postoperative insulin resistance (PIR), gastric fluid volume, preoperative discomfort, and variables of organ dysfunction in ASA physical status III-IV patients undergoing elective cardiac surgery, including those with noninsulin-dependent Type-2 diabetes mellitus. Before surgery, 188 patients were randomized to receive a clear 12.5% carbohydrate drink (CHO), flavored water (placebo), or to fast overnight (control). CHO and placebo were treated in double-blind format and received 800 mL of the corresponding beverage in the evening and 400 mL 2 h before surgery. Patients were monitored from induction of general anesthesia until 24 h postoperatively. Exogenous insulin requirements to control blood glucose levels

Dehydration, hemodynamics and fluid volume optimization after induction of general anesthesia.

PubMed

Li, Yuhong; He, Rui; Ying, Xiaojiang; Hahn, Robert G

2014-01-01

Fluid volume optimization guided by stroke volume measurements reduces complications of colorectal and high-risk surgeries. We studied whether dehydration or a strong hemodynamic response to general anesthesia increases the probability of fluid responsiveness before surgery begins. Cardiac output, stroke volume, central venous pressure and arterial pressures were measured in 111 patients before general anesthesia (baseline), after induction and stepwise after three bolus infusions of 3 ml/kg of 6% hydroxyethyl starch 130/0.4 (n=86) or Ringer's lactate (n=25). A subgroup of 30 patients who received starch were preloaded with 500 ml of Ringer's lactate. Blood volume changes were estimated from the hemoglobin concentration and dehydration was estimated from evidence of renal water conservation in urine samples. Induction of anesthesia decreased the stroke volume to 62% of baseline (mean); administration of fluids restored this value to 84% (starch) and 68% (Ringer's). The optimized stroke volume index was clustered around 35-40 ml/m2/beat. Additional fluid boluses increased the stroke volume by ≥10% (a sign of fluid responsiveness) in patients with dehydration, as suggested by a low cardiac index and central venous pressure at baseline and by high urinary osmolality, creatinine concentration and specific gravity. Preloading and the hemodynamic response to induction did not correlate with fluid responsiveness. The blood volume expanded 2.3 (starch) and 1.8 (Ringer's) times over the infused volume. Fluid volume optimization did not induce a hyperkinetic state but ameliorated the decrease in stroke volume caused by anesthesia. Dehydration, but not the hemodynamic response to the induction, was correlated with fluid responsiveness.

The Voronoi volume and molecular representation of molar volume: equilibrium simple fluids.

PubMed

Hunjan, Jagtar Singh; Eu, Byung Chan

2010-04-07

The Voronoi volume of simple fluids was previously made use of in connection with volume transport phenomena in nonequilibrium simple fluids. To investigate volume transport phenomena, it is important to develop a method to compute the Voronoi volume of fluids in nonequilibrium. In this work, as a first step to this goal, we investigate the equilibrium limit of the nonequilibrium Voronoi volume together with its attendant related molar (molal) and specific volumes. It is proved that the equilibrium Voronoi volume is equivalent to the molar (molal) volume. The latter, in turn, is proved equivalent to the specific volume. This chain of equivalences provides an alternative procedure of computing the equilibrium Voronoi volume from the molar volume/specific volume. We also show approximate methods of computing the Voronoi and molar volumes from the information on the pair correlation function. These methods may be employed for their quick estimation, but also provide some aspects of the fluid structure and its relation to the Voronoi volume. The Voronoi volume obtained from computer simulations is fitted to a function of temperature and pressure in the region above the triple point but below the critical point. Since the fitting function is given in terms of reduced variables for the Lennard-Jones (LJ) model and the kindred volumes (i.e., specific and molar volumes) are in essence equivalent to the equation of state, the formula obtained is a reduced equation state for simple fluids obeying the LJ model potential in the range of temperature and pressure examined and hence can be used for other simple fluids.

Hydrogen gas inhalation inhibits progression to the "irreversible" stage of shock after severe hemorrhage in rats.

PubMed

Matsuoka, Tadashi; Suzuki, Masaru; Sano, Motoaki; Hayashida, Kei; Tamura, Tomoyoshi; Homma, Koichiro; Fukuda, Keiichi; Sasaki, Junichi

2017-09-01

Mortality of hemorrhagic shock primarily depends on whether or not the patients can endure the loss of circulating volume until radical treatment is applied. We investigated whether hydrogen (H2) gas inhalation would influence the tolerance to hemorrhagic shock and improve survival. Hemorrhagic shock was achieved by withdrawing blood until the mean arterial blood pressure reached 30-35 mm Hg. After 60 minutes of shock, the rats were resuscitated with a volume of normal saline equal to four times the volume of shed blood. The rats were assigned to either the H2 gas (1.3% H2, 26% O2, 72.7% N2)-treated group or the control gas (26% O2, 74% N2)-treated group. Inhalation of the specified gas mixture began at the initiation of blood withdrawal and continued for 2 hours after fluid resuscitation. The survival rate at 6 hours after fluid resuscitation was 80% in H2 gas-treated rats and 30% in control gas-treated rats (p < 0.05). The volume of blood that was removed through a catheter to induce shock was significantly larger in the H2 gas-treated rats than in the control rats. Despite losing more blood, the increase in serum potassium levels was suppressed in the H2 gas-treated rats after 60 minutes of shock. Fluid resuscitation completely restored blood pressure in the H2 gas-treated rats, whereas it failed to fully restore the blood pressure in the control gas-treated rats. At 2 hours after fluid resuscitation, blood pressure remained in the normal range and metabolic acidosis was well compensated in the H2 gas-treated rats, whereas we observed decreased blood pressure and uncompensated metabolic acidosis and hyperkalemia in the surviving control gas-treated rats. H2 gas inhalation delays the progression to irreversible shock. Clinically, H2 gas inhalation is expected to stabilize the subject until curative treatment can be performed, thereby increasing the probability of survival after hemorrhagic shock.

Fluid shear stress enhances the cell volume decrease of osteoblast cells by increasing the expression of the ClC-3 chloride channel

PubMed Central

LIU, LI; CAI, SIYI; QIU, GUIXING; LIN, JIN

2016-01-01

ClC-3 is a volume-sensitive chloride channel that is responsible for cell volume adjustment and regulatory cell volume decrease (RVD). In order to evaluate the effects of fluid shear stress (FSS) stimulation on the osteoblast ClC-3 chloride channel, MC3T3-E1 cells were stimulated by FSS in the experimental group. Fluorescence quantitative polymerase chain reaction was used to detect changes in ClC-3 mRNA expression, the chloride ion fluorescent probe N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) was used to detect the chloride channel activity, and whole-cell patch clamping was used to monitor the changes in the volume-sensitive chloride current activated by a hypotonic environment following mechanical stimulation. The results show that the expression of the osteoblast chloride channel ClC-3 was significantly higher in the FSS group compared with the control group. MQAE fluorescence intensity was significantly reduced in the FSS group compared to the control group, suggesting that mechanical stimulation increased chloride channel activity and increased the efflux of intracellular chloride ions. Image analysis of osteoblast volume changes showed that osteoblast RVD was enhanced by mechanical stimulation. Whole-cell patch clamping showed that the osteoblast volume-sensitive chloride current was larger in the stimulated group compared to the control group, suggesting that elevated ClC-3 chloride channel expression results in an increased volume-sensitive chloride current. In conclusion, FSS stimulation enhances the RVD of osteoblast cell by increasing the expression of the ClC-3 and enhancing the chloride channel activity. PMID:27073622

Design of Accumulators and Liquid/Gas Charging of Single Phase Mechanically Pumped Fluid Loop Heat Rejection Systems

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Dudik, Brenda; Birur, Gajanana; Karlmann, Paul; Bame, David; Mastropietro, A. J.

2012-01-01

For single phase mechanically pumped fluid loops used for thermal control of spacecraft, a gas charged accumulator is typically used to modulate pressures within the loop. This is needed to accommodate changes in the working fluid volume due to changes in the operating temperatures as the spacecraft encounters varying thermal environments during its mission. Overall, the three key requirements on the accumulator to maintain an appropriate pressure range throughout the mission are: accommodation of the volume change of the fluid due to temperature changes, avoidance of pump cavitation and prevention of boiling in the liquid. The sizing and design of such an accumulator requires very careful and accurate accounting of temperature distribution within each element of the working fluid for the entire range of conditions expected, accurate knowledge of volume of each fluid element, assessment of corresponding pressures needed to avoid boiling in the liquid, as well as the pressures needed to avoid cavitation in the pump. The appropriate liquid and accumulator strokes required to accommodate the liquid volume change, as well as the appropriate gas volumes, require proper sizing to ensure that the correct pressure range is maintained during the mission. Additionally, a very careful assessment of the process for charging both the gas side and the liquid side of the accumulator is required to properly position the bellows and pressurize the system to a level commensurate with requirements. To achieve the accurate sizing of the accumulator and the charging of the system, sophisticated EXCEL based spreadsheets were developed to rapidly come up with an accumulator design and the corresponding charging parameters. These spreadsheets have proven to be computationally fast and accurate tools for this purpose. This paper will describe the entire process of designing and charging the system, using a case study of the Mars Science Laboratory (MSL) fluid loops, which is en route to Mars for an August 2012 landing.

Measuring P-V-T Phase Behavior with a Variable Volume View Cell

ERIC Educational Resources Information Center

Hoffmann, Markus M.; Salter, Jason D.

2004-01-01

An experiment using a variable volume cell is presented where students actively control and directly observe the phase equilibrium inside the view cell. Measuring and exploring P-V-T phase behavior through dielectric constant measurements conveys the important concept that solvent behavior can be changed continuously in the sc fluid state.

[Volume Homeostasis and Renal Function in Rats Exposed to Simulated and Actual Microgravity

NASA Technical Reports Server (NTRS)

Tucker, Bryan J.

1993-01-01

This project has investigated mechanisms that influence alterations in compartmental fluid and electrolyte balance in microgravity and evaluates countermeasures to control renal fluid and electrolyte losses. Determining the alterations due to space flight in fluid compartments and renal function is an important component in understanding long term adaptation to spaceflight and the contribution to post-flight orthostatic intolerance. Four definition phase studies and two studies examining neuro-humoral and vascular mechanisms have been completed.

A novel pressure-driven piezodispenser for nanoliter volumes.

PubMed

McGuire, Shawn; Fisher, Charles; Holl, Mark; Meldrum, Deirdre

2008-08-01

A successful dispensing device has been built for use in biotechnology applications requiring nanoliter volume liquid transfer. Air pressure is used as the primary driving force and is controlled via a high speed miniature solenoid valve as opposed to many existing systems that use a valve in line with constantly pressurized fluid to start and stop the dispensing action. This automated pressure-driven system is used to improve a typical piezodriven microdispenser. The resulting system is much less prone to failures resulting from air entrainment and can dispense much higher viscosity fluids than the microdispenser alone.

Development of a prototype fluid volume measurement system. [for urine volume measurement on space missions

NASA Technical Reports Server (NTRS)

Poppendiek, H. F.; Sabin, C. M.; Meckel, P. T.

1974-01-01

The research is reported in applying the axial fluid temperature differential flowmeter to a urine volume measurement system for space missions. The fluid volume measurement system is described along with the prototype equipment package. Flowmeter calibration, electronic signal processing, and typical void volume measurements are also described.

Fluid extravasation during hip arthroscopy.

PubMed

Stafford, Giles H; Malviya, Ajay; Villar, Richard N

2011-01-01

The amount of fluid that may be lost into the soft tissues during hip arthroscopic surgery is unknown. We measured the volumes of irrigation fluid infused, operating time, fluid pressures and volumes of fluid recovered in 36 therapeutic hip arthroscopies. We excluded those where fluid was lost to the floor, leaving 28 patients. The majority were undergoing surgery for the treatment of femoroacetabular impingement. In 5 patients an intra-articular contrast medium was instilled, in order to establish the likely location of any extravasated fluid. The mean operating time was 68 minutes (31 to 120), and the mean infusion pressure was 46 mm Hg (30 to 70). The mean volume of infused fluid was 9677 ml (95% confidence interval (CI) 7715 to 11638) and the mean volume of fluid recovered was 8544 ml (95% CI 6715 to 10373). The mean fluid extravasation loss into the peri-articular tissues was 1132 ml (95% CI 808 ml to 1456 ml). There was a significant correlation between the volume of extravasated fluid and both the length of operation and the volume of infused fluid used. We had no adverse events in our series. During arthroscopic hip surgery more than a litre of irrigation fluid may be extravasated into the soft tissues. In order to reduce problems related to this we attempt to keep operating times low, and maintain intra-operative fluid pressures as low as possible.

A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation.

PubMed

Libros, R; Philips, C M; Wolfson, M R; Shaffer, T H

2000-01-01

Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.

Maintenance fluid therapy and fluid creep impose more significant fluid, sodium, and chloride burdens than resuscitation fluids in critically ill patients: a retrospective study in a tertiary mixed ICU population.

PubMed

Van Regenmortel, Niels; Verbrugghe, Walter; Roelant, Ella; Van den Wyngaert, Tim; Jorens, Philippe G

2018-04-01

Research on intravenous fluid therapy and its side effects, volume, sodium, and chloride overload, has focused almost exclusively on the resuscitation setting. We aimed to quantify all fluid sources in the ICU and assess fluid creep, the hidden and unintentional volume administered as a vehicle for medication or electrolytes. We precisely recorded the volume, sodium, and chloride burdens imposed by every fluid source administered to 14,654 patients during the cumulative 103,098 days they resided in our 45-bed tertiary ICU and simulated the impact of important strategic fluid choices on patients' chloride burdens. In septic patients, we assessed the impact of the different fluid sources on cumulative fluid balance, an established marker of morbidity. Maintenance and replacement fluids accounted for 24.7% of the mean daily total fluid volume, thereby far exceeding resuscitation fluids (6.5%) and were the most important sources of sodium and chloride. Fluid creep represented a striking 32.6% of the mean daily total fluid volume [median 645 mL (IQR 308-1039 mL)]. Chloride levels can be more effectively reduced by adopting a hypotonic maintenance strategy [a daily difference in chloride burden of 30.8 mmol (95% CI 30.5-31.1)] than a balanced resuscitation strategy [daily difference 3.0 mmol (95% CI 2.9-3.1)]. In septic patients, non-resuscitation fluids had a larger absolute impact on cumulative fluid balance than did resuscitation fluids. Inadvertent daily volume, sodium, and chloride loading should be avoided when prescribing maintenance fluids in view of the vast amounts of fluid creep. This is especially important when adopting an isotonic maintenance strategy.

Physiologic mechanisms of circulatory and body fluid losses in weightlessness identified by mathematical modeling

NASA Technical Reports Server (NTRS)

Simanonok, K. E.; Srinivasan, R. S.; Charles, J. B.

1993-01-01

Central volume expansion due to fluid shifts in weightlessness is believed to activate adaptive reflexes which ultimately result in a reduction of the total circulating blood volume. However, the flight data suggests that a central volume overdistention does not persist, in which case some other factor or factors must be responsible for body fluid losses. We used a computer simulation to test the hypothesis that factors other than central volume overdistention are involved in the loss of blood volume and other body fluid volumes observed in weightlessness and in weightless simulations. Additionally, the simulation was used to identify these factors. The results predict that atrial volumes and pressures return to their prebedrest baseline values within the first day of exposure to head down tilt (HDT) as the blood volume is reduced by an elevated urine formation. They indicate that the mechanisms for large and prolonged body fluid losses in weightlessness is red cell hemoconcentration that elevates blood viscosity and peripheral resistance, thereby lowering capillary pressure. This causes a prolonged alteration of the balance of Starling forces, depressing the extracellular fluid volume until the hematocrit is returned to normal through a reduction of the red cell mass, which also allows some restoration of the plasma volume. We conclude that the red cell mass becomes the physiologic driver for a large 'undershoot' of the body fluid volumes after the normalization of atrial volumes and pressures.

The Effect of Neutral Peritoneal Dialysis Solution with Low Glucose-Degradation-Product on the Fluid Status and Body Composition – A Randomized Control Trial

PubMed Central

Szeto, Cheuk-Chun; Kwan, Bonnie C. H.; Chow, Kai-Ming; Cheng, Phyllis M. S.; Kwong, Vickie W. K.; Choy, Agnes S. M.; Law, Man-Ching; Leung, Chi-Bon; Li, Philip K. T.

2015-01-01

Background Previous studies report conflicting results on the benefit of peritoneal dialysis (PD) patients treated with low glucose degradation product (GDP) solution. The effects of low GDP solution on body fluid status and arterial pulse wave velocity (PWV) have not been studied. Methods We randomly assigned 68 incident PD patients to low GDP (Intervention Group) or conventional solutions (Control Group); 4 dropped off before they received the assigned treatment. Patients were followed for 52 weeks for changes in ultrafiltration, residual renal function, body fluid status and arterial PWV. Result After 52 weeks, Intervention Group had higher overhydration (3.1 ± 2.6 vs 1.9 ± 2.2 L, p = 0.045) and extracellular water volume (17.7 ± 3.9 vs 15.8 ± 3.1 L, p = 0.034) than Control Group. There was no significant difference in PWV between groups. There was no significant difference in residual renal function between the Groups. Intervention Group had lower ultrafiltration volume than Control Group at 4 weeks (0.45 ± .0.61 vs 0.90 ± 0.79 L/day, p = 0.013), but the difference became insignificant at later time points. Intervention Group had lower serum CRP levels than Control Group (4.17 ± 0.77 vs 4.91 ± 0.95 mg/dL, p < 0.0001). Conclusion Incident PD patients treated with low GDP solution have less severe systemic inflammation but trends of less ultrafiltration, and more fluid accumulation. However, the effects on ultrafiltration and fluid accumulation disappear with time. The long term effect of low GDP solution requires further study. Trial Registration ClinicalTrials.gov NCT00966615 PMID:26510186

Hypertonic 15% sodium pyruvate offers no initial resuscitation advantage compared with 8% hypertonic NACl in sheep with multiple hemorrhages.

PubMed

do Nascimento, Paulo; Vaid, Sumreen U; Hoskins, Stephen L; Espana, Jonathan M; Kinsky, Michael P; Kramer, George C

2007-05-01

Initial fluid resuscitation of hemorrhagic shock might be enhanced by the infusion of monocarboxylate-energy substrates. We evaluated hemodynamics, metabolism, and fluid dynamics for initial resuscitation of hemorrhage using small volume 15% sodium pyruvate solution (HPY) compared with osmotically matched 8% hypertonic saline (HS). Instrumented conscious sheep were hemorrhaged 25 mL/kg at time zero through 15 min (T0-T15) and 5 mL/kg for 5 min at T50 to T55 and T70 to T75. Fluid resuscitation from T30 to T180 was performed by a computer-controlled closed-loop system, which titrated infusion rate to a mean arterial pressure of 90 mmHg. Initial infusion was 4 mL/kg of either HPY or HS, followed by the administration of lactated Ringer. Both HPY and HS restored cardiac index similarly. The lactate/pyruvate ratio was used to assess metabolic debt and was significantly higher (T180), whereas oxygen delivery was significantly lower (T120) with HPY versus HS. Total fluid administered was similar, with 43.7 +/- 6.2 mL/kg for HPY and 39.4 +/- 6.8 mL/kg for HS. Plasma volume was similarly increased and approached baseline values for both groups. Initial resuscitation with small volume HPY offered no hemodynamic or metabolic advantage compared with small volume HS when the fluids were infused to an end point pressure.

Mathematical modelling of fluid transport and its regulation at multiple scales.

PubMed

Chara, Osvaldo; Brusch, Lutz

2015-04-01

Living matter equals water, to a first approximation, and water transport across barriers such as membranes and epithelia is vital. Water serves two competing functions. On the one hand, it is the fundamental solvent enabling random mobility of solutes and therefore biochemical reactions and intracellular signal propagation. Homeostasis of the intracellular water volume is required such that messenger concentration encodes the stimulus and not inverse volume fluctuations. On the other hand, water flow is needed for transport of solutes to and away from cells in a directed manner, threatening volume homeostasis and signal transduction fidelity of cells. Feedback regulation of fluid transport reconciles these competing objectives. The regulatory mechanisms often span across multiple spatial scales from cellular interactions up to the architecture of organs. Open questions relate to the dependency of water fluxes and steady state volumes on control parameters and stimuli. We here review selected mathematical models of feedback regulation of fluid transport at the cell scale and identify a general "core-shell" structure of such models. We propose that fluid transport models at other spatial scales can be constructed in a generalised core-shell framework, in which the core accounts for the biophysical effects of fluid transport whilst the shell reflects the regulatory mechanisms. We demonstrate the applicability of this framework for tissue lumen growth and suggest future experiments in zebrafish to test lumen size regulation mechanisms. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Shuttle cryogenics supply system optimization study. Volume 5, B-3, part 2: Appendix to programmers manual for math model

NASA Technical Reports Server (NTRS)

1973-01-01

A computer programmer's manual for a digital computer which will permit rapid and accurate parametric analysis of current and advanced attitude control propulsion systems is presented. The concept is for a cold helium pressurized, subcritical cryogen fluid supplied, bipropellant gas-fed attitude control propulsion system. The cryogen fluids are stored as liquids under low pressure and temperature conditions. The mathematical model provides a generalized form for the procedural technique employed in setting up the analysis program.

Shuttle cryogenic supply system optimization study. Volume 4: Cryogenic cooling in environmental control systems

NASA Technical Reports Server (NTRS)

1973-01-01

An analysis of cryogenic fluid cooling in the environmental control system of the space shuttle was conducted. The technique for treating the cryogenic fluid storage and supply tanks and subsystems as integrated systems was developed. It was concluded that a basic incompatibility exists between the heat generated and the cryogen usage rate and cryogens cannot be used to absorb the generated heat. The use of radiators and accumulators to provide additional cooling capability is recommended.

[Intraoperative fluid therapy during esophagectomy followed by repair].

PubMed

Sizov, V A; Raevskaya, M B; Kovalerova, N B; Ruchkin, D V; Subbotin, V V; Kazennov, V V; Ilyin, S A

To optimize fluid therapy in transhiatal eshophagectomy by using of goal-oriented infusion therapy based on stroke volume variation. Our trial enrolled 30 patients who underwent transhiatal esophagectomy followed by repair for the period 2011-2014. Patients were divided into 2 groups. The first group (LT) included 16 patients with liberal fluid therapy. The second group (GDT) consisted of 14 patients in whom goal-oriented fluid therapy was performed. Goal-oriented fluid therapy was implemented via stroke volume variation (SVV). Infusion rate was 6.7 ml/kg/h and 11.5 ml/kg/h in the main and control groups, respectively. Morbidity rate was 28.6% (n=4) and 62.5% (n=10) in the main and control groups respectively. Clavien-Dindo IV complications were lung atelectasis (n=2, 14%), pneumonia (n=1, 7%). Hydrothorax required puncture was noted in 1 (7%) case. Acute respiratory failure as complication IVa was in 1 (9%) patient. In the control group complications were registered in 10 (62.5%) patients. Complications I-II degree included lung atelectasis (n=4, 25%), cervical anastomosis failure (n=1, 6%); complications IVa were observed in 8 cases (50%). It was significant respiratory failure with reduced PO2/FiO2<300. Patients of the main group required less time for postoperative mechanical ventilation (120 [90-300] vs. 315 [215-810] min (p=0.02) and ICU-stay (0.83 [0.7-0.8] vs. 1.75 [1.25-2.75] (p=0.0022).

Squeeze strengthening of magnetorheological fluids using mixed mode operation

NASA Astrophysics Data System (ADS)

Becnel, A. C.; Sherman, S. G.; Hu, W.; Wereley, N. M.

2015-05-01

This research details a novel method of increasing the shear yield stress of magnetorheological fluids by combining shear and squeeze modes of operation to manipulate particle chain structures, so-called squeeze strengthening. Using a custom built Searle cell magnetorheometer, which is a model device emulating a rotary magnetorheological energy absorber (MREA), the contribution of squeeze strengthening to the total controllable yield force is experimentally investigated. Using an eccentric rotating inner cylinder, characterization data from large (1 mm) and small (0.25 mm) nominal gap geometries are compared to investigate the squeeze strengthening effect. Details of the experimental setup and method are presented, and a hybrid model is used to explain experimental trends. This study demonstrates that it is feasible, utilizing squeeze strengthening to increase yield stress, to either (1) design a rotary MREA of a given volume to achieve higher energy absorption density (energy absorbed normalized by active fluid volume), or (2) reduce the volume of a given rotary MREA to achieve the same energy absorption density.

Effect of fluid loading on left ventricular volume and stroke volume variability in patients with end-stage renal disease: a pilot study

PubMed Central

Kanda, Hirotsugu; Hirasaki, Yuji; Iida, Takafumi; Kanao-Kanda, Megumi; Toyama, Yuki; Kunisawa, Takayuki; Iwasaki, Hiroshi

2015-01-01

Purpose The aim of this study was to investigate fluid loading-induced changes in left ventricular end-diastolic volume (LVEDV) and stroke volume variability (SVV) in patients with end-stage renal disease (ESRD) using real-time three-dimensional transesophageal echocardiography and the Vigileo-FloTrac system. Patients and methods After obtaining ethics committee approval and informed consent, 28 patients undergoing peripheral vascular procedures were studied. Fourteen patients with ESRD on hemodialysis (HD) were assigned to the HD group and 14 patients without ESRD were assigned to the control group. Institutional standardized general anesthesia was provided in both groups. SVV was measured using the Vigileo-FloTrac system. Simultaneously, a full-volume three-dimensional transesophageal echocardiography dataset was acquired to measure LVEDV, left ventricular end-systolic volume, and left ventricular ejection fraction. Measurements were obtained before and after loading 500 mL hydroxyethyl starch over 30 minutes in both groups. Results In the control group, intravenous colloid infusion was associated with a significant decrease in SVV (13.8%±2.6% to 6.5%±2.6%, P<0.001) and a significant increase in LVEDV (83.6±23.4 mL to 96.1±28.8 mL, P<0.001). While SVV significantly decreased after infusion in the HD group (16.2%±6.0% to 6.2%±2.8%, P<0.001), there was no significant change in LVEDV. Conclusion Our preliminary data suggest that fluid responsiveness can be assessed not by LVEDV but also by SVV due to underlying cardiovascular pathophysiology in patients with ESRD. PMID:26527879

Impact of speed and magnitude of weight loss on the development of brain trophic changes in adolescents with anorexia nervosa: a case control study.

PubMed

Bomba, Monica; Riva, Anna; Veggo, Federica; Grimaldi, Marco; Morzenti, Sabrina; Neri, Francesca; Nacinovich, Renata

2013-02-19

Anorexia nervosa commonly arises during adolescence and is associated with more than one medical morbidity. Abnormalities in brain structure (defined as "pseudoatrophy") are common in adolescents with anorexia nervosa; however, their correlations with endocrinological profiles and clinical parameters are still unclear. In particular, no study has described the impact of BMI (body mass index) variations (speed and magnitude of weight loss) on cerebral trophism changes. Eleven adolescents with anorexia nervosa and 8 healthy controls underwent cerebral MRI (magnetic resonance imaging) examination to obtain global and partial volumes (gray matter, white matter and cerebrospinal fluid) and clinical evaluation. The Mann-Whitney U test was used to compare partial volumes and clinical variables between cases and controls. The Spearman non-parametric test was performed in order to explore correlations between the variables studied. The patients diagnosed with AN showed significantly increased cerebrospinal fluid (CSF) volumes and decreased total gray (GM) and white matter (WM) volumes. The degree of weight loss (deltaBMI) correlated inversely with the GM volume; the increase of CSF compartment correlated directly with the rapidity of weight loss (DeltaBMI/disease duration). This study suggests a correlation between cerebral alterations in AN and the speed and magnitude of weight loss, and outlines its importance for the therapeutic treatment.

Comparison of the effect of a single dose of erythromycin with pantoprazole on gastric content volume and acidity in elective general surgery patients

PubMed Central

Bhatia, Nidhi; Palta, Sanjeev; Arora, Kanika

2011-01-01

Introduction: Pulmonary aspiration of gastric contents remains one of the most feared complications of anesthesia. A gastric pH of 2.5 or less and a volume of 25 ml (0.4 ml/kg body weight) or more in average adult patients are considered critical factors for the development of pulmonary damage in adults. Materials and Methods: This study compared the efficacy of a single oral dose of erythromycin (a macrolide antibiotic) with oral pantoprazole (a proton pump inhibitor) on pre-operative gastric fluid volume and pH in a prospective, randomized, double-blind controlled fashion in 80 adult patients (of ASA physical status I and II) planned for elective surgery under general anesthesia. Patients were divided into two groups of 40 patients each. The pantoprazole group (Group I) received oral pantoprazole 40 mg and the erythromycin group (Group II) received oral erythromycin 250 mg at least 1 h prior to the induction of anesthesia. After tracheal intubation, gastric fluid was aspirated via a Salem Sump tube and its volume and pH were measured. Results: Although both erythromycin and pantoprazole decreased the gastric fluid volume to a similar extent, the decrease in gastric fluid acidity by pantoprazole was significantly greater than that by erythromycin. The proportion of patients at risk of pulmonary aspiration according to traditional criteria, i.e. pH ≤2.5 and volume ≥25ml, was lower in the pantoprazole group. Conclusion: Administration of pantoprazole was found to be more useful than a sub-therapeutic dose of erythromycin in decreasing both volume and acidity of gastric content. PMID:21772679

Transpiring purging access probe for particulate laden or hazardous environments

DOEpatents

VanOsdol, John G

2013-12-03

An access probe for remote-sensing access through a viewing port, viewing volume, and access port into a vessel. The physical boundary around the viewing volume is partially formed by a porous sleeve lying between the viewing volume and a fluid conduit. In a first mode of operation, a fluid supplied to the fluid conduit encounters the porous sleeve and flows through the porous material to maintain the viewing volume free of ash or other matter. When additional fluid force is needed to clear the viewing volume, the pressure of the fluid flow is increased sufficiently to slidably translate the porous sleeve, greatly increasing the flow into the viewing volume. The porous sleeve is returned to position by an actuating spring. The access probe thereby provides for alternate modes of operation based on the pressure of an actuating fluid.

Initial 12-h operative fluid volume is an independent risk factor for pleural effusion after hepatectomy.

PubMed

Cheng, Xiang; Wu, Jia-Wei; Sun, Ping; Song, Zi-Fang; Zheng, Qi-Chang

2016-12-01

Pleural effusion after hepatectomy is associated with significant morbidity and prolonged hospital stays. Several studies have addressed the risk factors for postoperative pleural effusion. However, there are no researches concerning the role of the initial 12-h operative fluid volume. The aim of this study was to evaluate whether the initial 12-h operative fluid volume during liver resection is an independent risk factor for pleural effusion after hepatectomy. In this study, we retrospectively analyzed clinical data of 470 patients consecutively undergoing elective hepatectomy between January 2011 and December 2012. We prospectively collected and retrospectively analyzed baseline and clinical data, including preoperative, intraoperative, and postoperative variables. Univariate and multivariate analyses were carried out to identify whether the initial 12-h operative fluid volume was an independent risk factor for pleural effusion after hepatectomy. The multivariate analysis identified 2 independent risk factors for pleural effusion: operative time [odds ratio (OR)=10.2] and initial 12-h operative fluid volume (OR=1.0003). Threshold effect analyses revealed that the initial 12 h operative fluid volume was positively correlated with the incidence of pleural effusion when the initial 12-h operative fluid volume exceeded 4636 mL. We conclude that the initial 12-h operative fluid volume during liver resection and operative time are independent risk factors for pleural effusion after hepatectomy. Perioperative intravenous fluids should be restricted properly.

High speed flow cytometer droplet formation system and method

DOEpatents

Van den Engh, Ger

2000-01-01

A droplet forming flow cytometer system allows high speed processing without the need for high oscillator drive powers through the inclusion of an oscillator or piezoelectric crystal such as within the nozzle volume or otherwise unidirectionally coupled to the sheath fluid. The nozzle container continuously converges so as to amplify unidirectional oscillations which are transmitted as pressure waves through the nozzle volume to the nozzle exit so as to form droplets from the fluid jet. The oscillator is directionally isolated so as to avoid moving the entire nozzle container so as to create only pressure waves within the sheath fluid. A variation in substance concentration is achieved through a movable substance introduction port which is positioned within a convergence zone to vary the relative concentration of substance to sheath fluid while still maintaining optimal laminar flow conditions. This variation may be automatically controlled through a sensor and controller configuration. A replaceable tip design is also provided whereby the ceramic nozzle tip is positioned within an edge insert in the nozzle body so as to smoothly transition from nozzle body to nozzle tip. The nozzle tip is sealed against its outer surface to the nozzle body so it may be removable for cleaning or replacement.

3D numerical simulations of oblique droplet impact onto a deep liquid pool

NASA Astrophysics Data System (ADS)

Gelderblom, Hanneke; Reijers, Sten A.; Gielen, Marise; Sleutel, Pascal; Lohse, Detlef; Xie, Zhihua; Pain, Christopher C.; Matar, Omar K.

2017-11-01

We study the fluid dynamics of three-dimensional oblique droplet impact, which results in phenomena that include splashing and cavity formation. An adaptive, unstructured mesh modelling framework is employed here, which can modify and adapt unstructured meshes to better represent the underlying physics of droplet dynamics, and reduce computational effort without sacrificing accuracy. The numerical framework consists of a mixed control-volume and finite-element formulation, a volume-of-fluid-type method for the interface-capturing based on a compressive control-volume advection method. The framework also features second-order finite-element methods, and a force-balanced algorithm for the surface tension implementation, minimising the spurious velocities often found in many simulations involving capillary-driven flows. The numerical results generated using this framework are compared with high-speed images of the interfacial shapes of the deformed droplet, and the cavity formed upon impact, yielding good agreement. EPSRC, UK, MEMPHIS program Grant (EP/K003976/1), RAEng Research Chair (OKM).

Amylase, lipase, and volume of drainage fluid in gastrectomy for the early detection of complications caused by pancreatic leakage.

PubMed

Seo, Kyung Won; Yoon, Ki Young; Lee, Sang Ho; Shin, Yeon Myung; Choi, Kyung Hyun; Hwang, Hyun Yong

2011-12-01

Pancreatic leakage is a serious complication of gastrectomy due to stomach cancer. Therefore, we analyzed amylase and lipase concentrations in blood and drainage fluid, and evaluated the volume of drainage fluid to discern their usefulness as markers for the early detection of serious pancreatic leakage requiring reoperation after gastrectomy. From January 2001 to December 2007, we retrospectively analyzed data from 24,072 patient samples. We divided patients into two groups; 1) complications with pancreatic leakage (CG), and 2) no complications associated with pancreatic leakage (NCG). Values of amylase and lipase in the blood and drainage fluid, volume of the drainage fluid, and relationships among the volumes, amylase values, and lipase values in the drainage fluid were evaluated, respectively in the two groups. The mean amylase values of CG were significantly higher than those of NCG in blood and drainage fluid (P < 0.05). For lipase, statistically significant differences were observed in drainage fluid (P < 0.05). The mean volume (standard deviation) of the drained fluid through the tube between CG (n = 22) and NCG (n = 236) on postoperative day 1 were 368.41 (266.25) and 299.26 (300.28), respectively. There were no statistically significant differences between the groups (P = 0.298). There was a correlation between the amylase and lipase values in the drainage fluid (r = 0.812, P = 0.000). Among postoperative amylase and lipase values in blood and drainage fluid, and the volume of drainage fluid, the amylase in drainage fluid was better differentiated between CG and NCG than other markers. The volume of the drainage fluid did not differ significantly between groups.

The control of ultrasonic transmission by the metamaterials structure of electrorheological fluid and metal foam

NASA Astrophysics Data System (ADS)

Li, Linlin; Wang, Mingzhong; Wang, Jiahui; Zhao, Xiaopeng

2017-11-01

A metamaterial structure formed by foamed metal and starch and oil-based electrorheological (ER) fluid is designed in this paper. Experiments show that the metamaterial structure exhibits a regulation effect on the amplitude and phase of the transmitted waves of 35-80 kHz ultra-wideband ultrasonic waves in water. With the increase of the electric field, the transmission amplitude and phase of the ultrasonic wave increases, whereas the control ability of the same gradient electric field decreases. The amplitude of the transmission controlled by the metamaterial structure and electric field increases at first, and then decreases with the increase in volume fraction of the ER fluid. Thus, it is thought that the interaction between the microstructure produced by the rheological properties of the ER fluid and the porous foam metal affects the propagation of the acoustic wave.

Measurement of net whole-body transcapillary fluid transport and effective vascular compliance in humans

NASA Technical Reports Server (NTRS)

Watenpaugh, D. E.; Gaffney, F. A.; Schneider, S. M. (Principal Investigator)

1998-01-01

BACKGROUND: Net whole-body transcapillary fluid transport (TFT) between the circulation and the interstitial (extravascular) space may be calculated as: IV - deltaPV - UV - IL, where IV=infused or ingested volume (when applicable), deltaPV = change in plasma volume, UV=urine volume, and IL=insensible loss. RESULTS: Infusion of 30 mL/kg isotonic saline over 25 minutes increased supine TFT from a basal capillary reabsorption of -106+/-24 mL/h (mean+/-SE) to a net filtration of 1,229+/-124 mL/h. One hour after infusion, reabsorption of -236+/-102 mL/h was seen, and control reabsorption levels returned by 3 hours. Four hours of 30 mm Hg lower body negative pressure (LBNP) elicited no net TFT, probably because of upper body reabsorptive compensation for lower body capillary filtration. When ingestion of 1 L of isotonic saline accompanied LBNP, filtration of 145+/-10 mL/h occurred. Reabsorption of extravascular fluid into the circulation always followed LBNP. CONCLUSION: Application of this technique could aid understanding of physiologic conditions, experimental interventions, disease states, and therapies that cause or are influenced by fluid shifts between intravascular and interstitial compartments.

Advances in Engineering Science, Volume 4

NASA Technical Reports Server (NTRS)

1976-01-01

The following areas of flight science are discussed in detail; (1) inviscid flow, (2) viscous flow, (3) aircraft aerodynamics, (4) fluid mechanics, (5) propulsion and combustion, and (6) flight dynamics and control.

A Dual Wedge Microneedle for sampling of perilymph solution via round window membrane

PubMed Central

Watanabe, Hirobumi; Cardoso, Luis; Lalwani, Anil K.; Kysar, Jeffrey W.

2017-01-01

Objective Precision medicine for inner-ear disease is hampered by the absence of a methodology to sample inner-ear fluid atraumatically. The round window membrane (RWM) is an attractive portal for accessing cochlear fluids as it heals spontaneously. In this study, we report on the development of a microneedle for perilymph sampling that minimizes size of RWM perforation, facilitates quick aspiration, and provides precise volume control. Methods Considering the mechanical anisotropy of the RWM and hydrodynamics through a microneedle, a 31G stainless steel pipe was machined into wedge-shaped design via electrical discharge machining. Guinea pig RWM was penetrated in vitro, and 1 μ1 of perilymph was sampled and analyzed via UV-vis spectroscopy. Results The prototype wedge shaped needle created oval perforation with minor and major diameter of 143 and 344 μm (n=6). The sampling duration and standard deviation of aspirated volume were seconds and 6.8% respectively. The protein concentration was 1.74 mg/mL. Conclusion The prototype needle facilitated precise perforation of RWMs and rapid aspiration of cochlear fluid with precise volume control. The needle design is promising and requires testing in human cadaveric temporal bone and further optimization to become clinically viable. PMID:26888440

Cytokine signalling in rat pulp interstitial fluid and transcapillary fluid exchange during lipopolysaccharide-induced acute inflammation

PubMed Central

Bletsa, Athanasia; Berggreen, Ellen; Fristad, Inge; Tenstad, Olav; Wiig, Helge

2006-01-01

The dental pulp consists of loose connective tissue encased in rigid dentinal walls. Because of its topography the tissue has low interstitial compliance and limited capacity to expand during fluid volume changes. Due to limitations regarding access to interstitial fluid, basic knowledge on transcapillary fluid transport parameters is lacking for this organ. The scope of this project was dual: first we aimed at establishing a method for isolation of pulp interstitial fluid (IF), and second we applied the method in rats subjected to lipopolysaccharide (LPS)-induced endotoxaemia. The aim was to measure colloid osmotic pressure (COP) and pro-inflammatory cytokines in the pulp IF during acute inflammation. Fluid volumes and pulpal blood flow (PBF) were measured to obtain more information about microcirculatory changes that take place in this pulpitis model. By centrifugation of incisor pulp at 239 g we were able to extract fluid representative for IF. Pulp IF had a relative high control COP (∼83% of plasma COP) and was similar to plasma COP 3 h after LPS challenge. The pulp exhibited a high content of IF (0.60 ± 0.03 ml (g wet weight)−1) and a vascular volume of 0.03 ± 0.01 ml (g w.w.)−1 No differences were observed in the distribution of fluid volumes after 1.5 and 3 h LPS exposure. PBF and systemic blood pressure dropped significantly after LPS administration. PBF remained low whereas systemic blood pressure was re-established during the 3-h period, implying organ dysfunction. There was a differential pattern of cytokine expression in pulp IF and serum with cytokines such as IL-1α, IL-1β and TNF-α locally produced, whereas others such as IFN-γ and IL-6 were produced systemically and probably spilled over to the pulp IF after LPS exposure. Our findings show that pulp IF can be isolated by centrifugation and that this method is useful when studying fluid balance and extracellular signalling mechanisms in the dental pulp in normal and pathological conditions. PMID:16527857

Body Fluid Regulation and Hemopoiesis in Space Flight

NASA Technical Reports Server (NTRS)

1997-01-01

In this session, Session JA2, the discussion focuses on the following topics: Bodymass and Fluid Distribution During Longterm Spaceflight with and without Countermeasures; Plasma Volume, Extracellular Fluid Volume, and Regulatory Hormones During Long-Term Space Flight; Effect of Microgravity and its Ground-Based Models on Fluid Volumes and Hemocirculatory Volumes; Seventeen Weeks of Horizontal Bed Rest, Lower Body Negative Pressure Testing, and the Associated Plasma Volume Response; Evaporative Waterloss in Space Theoretical and Experimental Studies; Erythropoietin Under Real and Simulated Micro-G Conditions in Humans; and Vertebral Bone Marrow Changes Following Space Flight.

Effects of Hydration and Calcium Supplementation on Urine Calcium Concentration in Healthy Postmenopausal Women.

PubMed

Harris, Susan S; Dawson-Hughes, Bess

2015-01-01

The aim of this study was to determine whether calcium supplementation, compared with placebo, increases urine calcium concentrations to levels indicative of increased renal stone risk, and the role that fluid intake, as indicated by urine volume, may play in mitigating this risk. This is a secondary analysis of data from a randomized placebo-controlled trial of 500 mg/d calcium supplementation to prevent bone loss. Subjects were 240 white postmenopausal women age 40 to 70 years in good general health. Effects of supplementation on 1-year changes in 24h urine calcium concentration and urine volume were examined. Both treatment group and urine volume were strong independent predictors of urine calcium concentration (p < 0.001). Among subjects with urine volume under 2 L/24 h, more than half of placebo subjects were at lowest risk for renal stones compared with less than 35% of calcium-supplemented subjects. Among those with higher urine volumes, all placebo subjects and more than 80% of calcium supplemented subjects were at lowest risk. The increased risk of renal stones with calcium supplement use may be largely eliminated with adequate fluid intake, but older adults may not spontaneously consume adequate fluids to minimize this risk and should be counseled to do so.

System and Method for Wirelessly Determining Fluid Volume

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

2009-01-01

A system and method are provided for determining the volume of a fluid in container. Sensors are positioned at distinct locations in a container of a fluid. Each sensor is sensitive to an interface defined by the top surface of the fluid. Interfaces associated with at least three of the sensors are determined and used to find the volume of the fluid in the container in a geometric process.

Sildenafil Citrate Therapy for Oligohydramnios: A Randomized Controlled Trial.

PubMed

Maher, Mohammad Ahmed; Sayyed, Tarek Mohammad; Elkhouly, Nabih

2017-04-01

To compare sildenafil plus hydration with hydration alone in improving the amniotic fluid index and neonatal outcomes in pregnancies complicated by idiopathic oligohydramnios ( amniotic fluid index less than 5 cm without underlying maternal or fetal causes and with normal fetal growth). This was an open-label randomized trial for women carrying singleton pregnancies at 30 weeks of gestation or more with idiopathic oligohydramnios detected during routine ultrasonogram. Women received either oral sildenafil citrate (25 mg every 8 hours) plus intravenous infusion of 2 L isotonic solution or fluids only until delivery. The primary study outcome was the amniotic fluid volume at 6 weeks of follow-up or the final volume before delivery, whichever occurred first. Secondary outcomes were duration of pregnancy prolongation, mode of delivery, and select neonatal outcomes. The study was powered to detect a 45% difference between groups, so, at an α level of 0.05 and 80% power, a sample size of 167 women was required. From February 24, 2015, through April 2016, 196 women were screened and 184 were randomized. Follow-up was completed in 166 (90%): 82 in the sildenafil group and 84 in the hydration group. Baseline characteristics were similar between groups. The amniotic fluid volume was higher in the sildenafil group at the final assessment (11.5 compared with 5.4 cm, P=.02). The sildenafil group delivered later (38.3 compared with 36.0 weeks of gestation, P=.001), had a lower rate of cesarean delivery (28% compared with 73%), and their neonates were less likely to be admitted to the neonatal intensive care unit (11% compared with 41%, P=.001). Sildenafil citrate increases amniotic fluid volume in pregnancies complicated by oligohydramnios. ClinicalTrials.gov, www.clinicaltrials.gov, NCT02372487.

Incorporating Dynamic Assessment of Fluid Responsiveness Into Goal-Directed Therapy: A Systematic Review and Meta-Analysis

PubMed Central

Fridfinnson, Jason A.; Kumar, Anand; Blanchard, Laurie; Rabbani, Rasheda; Bell, Dean; Funk, Duane; Turgeon, Alexis F.; Abou-Setta, Ahmed M.; Zarychanski, Ryan

2017-01-01

Objective: Dynamic tests of fluid responsiveness have been developed and investigated in clinical trials of goal-directed therapy. The impact of this approach on clinically relevant outcomes is unknown. We performed a systematic review and meta-analysis to evaluate whether fluid therapy guided by dynamic assessment of fluid responsiveness compared with standard care improves clinically relevant outcomes in adults admitted to the ICU. Data Sources: Randomized controlled trials from MEDLINE, EMBASE, CENTRAL, clinicaltrials.gov, and the International Clinical Trials Registry Platform from inception to December 2016, conference proceedings, and reference lists of relevant articles. Study Selection: Two reviewers independently identified randomized controlled trials comparing dynamic assessment of fluid responsiveness with standard care for acute volume resuscitation in adults admitted to the ICU. Data Extraction: Two reviewers independently abstracted trial-level data including population characteristics, interventions, clinical outcomes, and source of funding. Our primary outcome was mortality at longest duration of follow-up. Our secondary outcomes were ICU and hospital length of stay, duration of mechanical ventilation, and frequency of renal complications. The internal validity of trials was assessed in duplicate using the Cochrane Collaboration’s Risk of Bias tool. Data Synthesis: We included 13 trials enrolling 1,652 patients. Methods used to assess fluid responsiveness included stroke volume variation (nine trials), pulse pressure variation (one trial), and stroke volume change with passive leg raise/fluid challenge (three trials). In 12 trials reporting mortality, the risk ratio for death associated with dynamic assessment of fluid responsiveness was 0.59 (95% CI, 0.42–0.83; I2 = 0%; n = 1,586). The absolute risk reduction in mortality associated with dynamic assessment of fluid responsiveness was –2.9% (95% CI, –5.6% to –0.2%). Dynamic assessment of fluid responsiveness was associated with reduced duration of ICU length of stay (weighted mean difference, –1.16 d [95% CI, –1.97 to –0.36]; I2 = 74%; n = 394, six trials) and mechanical ventilation (weighted mean difference, –2.98 hr [95% CI, –5.08 to –0.89]; I2 = 34%; n = 334, five trials). Three trials were adjudicated at unclear risk of bias; the remaining trials were at high risk of bias. Conclusions: In adult patients admitted to intensive care who required acute volume resuscitation, goal-directed therapy guided by assessment of fluid responsiveness appears to be associated with reduced mortality, ICU length of stay, and duration of mechanical ventilation. High-quality clinical trials in both medical and surgical ICU populations are warranted to inform routine care. PMID:28817481

Fluid Volume Overload and Congestion in Heart Failure: Time to Reconsider Pathophysiology and How Volume Is Assessed.

PubMed

Miller, Wayne L

2016-08-01

Volume regulation, assessment, and management remain basic issues in patients with heart failure. The discussion presented here is directed at opening a reassessment of the pathophysiology of congestion in congestive heart failure and the methods by which we determine volume overload status. Peer-reviewed historical and contemporary literatures are reviewed. Volume overload and fluid congestion remain primary issues for patients with chronic heart failure. The pathophysiology is complex, and the simple concept of intravascular fluid accumulation is not adequate. The dynamics of interstitial and intravascular fluid compartment interactions and fluid redistribution from venous splanchnic beds to central pulmonary circulation need to be taken into account in strategies of volume management. Clinical bedside evaluations and right heart hemodynamic assessments can alert clinicians of changes in volume status, but only the quantitative measurement of total blood volume can help identify the heterogeneity in plasma volume and red blood cell mass that are features of volume overload in patients with chronic heart failure and help guide individualized, appropriate therapy-not all volume overload is the same. © 2016 American Heart Association, Inc.

The interrelationship of research in the laboratory and the field to assess hydration status and determine mechanisms involved in water regulation during physical activity.

PubMed

Stachenfeld, Nina S

2014-05-01

Changes in skin blood and sweating are the primary mechanisms for heat loss in humans. A hot, humid environment concomitant with dehydration limits the ability to increase skin blood flow for the purpose of transferring heat from the body core to skin surface and evaporate sweat to maintain core temperature within safe limits during exercise. Adequate hydration improves thermoregulation by maintaining blood volume to support skin blood flow and sweating. Humans rely on fluid intake to maintain total body water and blood volume, and have developed complex mechanisms to sense changes in the amount and composition of fluid in the body. This paper addresses the interrelationship of research in the laboratory and the field to assess hydration status involved in body water and temperature regulation during exercise. In the controlled setting of a research laboratory, investigators are able to investigate the contributions of volume and tonicity of fluid in the plasma to body water and temperature regulation during exercise and recovery. For example, laboratory studies have shown that tonicity in a rehydration beverage maintains the thirst mechanism (and stimulates drinking), and contributes to the ongoing stimulation of renal fluid retention hormones, ultimately leading to a more complete rehydration. Research in the field cannot control the environment precisely, but these studies provide a natural, 'real-life' setting to study fluid and temperature regulation during exercise. The conditions encountered in the field are closest to the environment during competition, and data collected in the field can have an immediate impact on performance and safety during exercise. There is an important synergy between these two methods of collecting data that support performance and protect athletes from harm during training and improve performance during competition.

Hemodynamic and permeability characteristics of acute experimental necrotizing enterocolitis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, M.J.; Adams, J.; Gu, X.A.

1990-10-01

We examined the local hemodynamic response of intestinal loops during acute necrotizing enterocolitis (NEC) in anesthetized rabbits. NEC was induced in ileal loops by transmural injection of a solution containing casein (10 mg/ml) and calcium gluconate (50 mg/ml) acidified to pH 4.0 with propionic or acetic acid. Control loops received casein only (pH 5.0). Mucosal damage was quantified by the blood-to-lumen movement of (51Cr)EDTA, fluid shifts into the lumen, and histology. Mean arterial pressure and loop blood flow were steady over the 3-hr period, loop fluid volume decreased, and there was no evidence of necrosis or epithelial damage. In loopsmore » receiving acidified casein and calcium gluconate, there was an immediate dramatic increase in loop blood flow that returned to baseline by 50 min. In addition, loop fluid volume was dramatically increased, necrosis was noted in the form of blunting and loss of villi, and sevenfold increase in (51Cr)EDTA permeability was evident. Administration of CV 1808 (30 mg/kg/hr), a selective adenosine2 agonist, which maintained and elevated loop blood flow throughout the 3 hr protocol, failed to alter the changes in loop fluid volume or prevent necrosis. Histamine levels in loop fluid levels were significantly elevated 20-30 min after NEC induction when compared to saline controls, indicating an early activation of mucosal defenses with this luminal insult. Thus, this model of NEC is characterized by a transient, acute hyperemia, increased intestinal permeability, and histamine release. As mucosal damage was independent of ischemia and could not be prevented by vasodilatory therapy, this model supports the clinical findings that NEC is correlated with luminal factors related to feeding and independent of cardiovascular stress.« less

Fluid intake and changes in limb volumes in male ultra-marathoners: does fluid overload lead to peripheral oedema?

PubMed

Bracher, Alexia; Knechtle, Beat; Gnädinger, Markus; Bürge, Jolanda; Rüst, Christoph Alexander; Knechtle, Patrizia; Rosemann, Thomas

2012-03-01

An increase in body mass due to oedema has been previously described. The aim of this study was to investigate a potential association between both fluid and electrolyte intake and the formation of peripheral oedemas. Fluid and electrolyte intakes and the changes in limb volumes in 50 male 100-km ultra-marathoners were measured. Pre- and post-race serum sodium concentration ([Na(+)]), serum aldosterone concentration, serum copeptin concentration, serum and urine osmolality and body mass were determined. Fluid intake, renal function parameters and urinary output, as well as the changes of volume in the extremities, were measured. The changes of volume in the limbs were measured using plethysmography. Serum [Na(+)] increased by 1.6%; body mass decreased by 1.9 kg. Serum copeptin and aldosterone concentrations were increased. The change in serum copeptin concentration and the change in serum [Na(+)] correlated positively; the change in serum [Na(+)] and body mass correlated negatively. A mean fluid intake of 0.58 L/h was positively related to running speed and negatively to post-race serum [Na(+)]. Total fluid intake was positively related to the changes in both arm and lower leg volumes. Running speed was positively associated with the changes in arm and lower leg volumes; race time was related to the changes in serum copeptin or aldosterone concentrations. To conclude, fluid intake was related to the changes in limb volumes, where athletes with an increased fluid intake developed an increase in limb volumes.

Quantification of the cerebrospinal fluid from a new whole body MRI sequence

NASA Astrophysics Data System (ADS)

Lebret, Alain; Petit, Eric; Durning, Bruno; Hodel, Jérôme; Rahmouni, Alain; Decq, Philippe

2012-03-01

Our work aims to develop a biomechanical model of hydrocephalus both intended to perform clinical research and to assist the neurosurgeon in diagnosis decisions. Recently, we have defined a new MR imaging sequence based on SPACE (Sampling Perfection with Application optimized Contrast using different flip-angle Evolution). On these images, the cerebrospinal fluid (CSF) appears as a homogeneous hypersignal. Therefore such images are suitable for segmentation and for volume assessment of the CSF. In this paper we present a fully automatic 3D segmentation of such SPACE MRI sequences. We choose a topological approach considering that CSF can be modeled as a simply connected object (i.e. a filled sphere). First an initial object which must be strictly included in the CSF and homotopic to a filled sphere, is determined by using a moment-preserving thresholding. Then a priority function based on an Euclidean distance map is computed in order to control the thickening process that adds "simple points" to the initial thresholded object. A point is called simple if its addition or its suppression does not result in change of topology neither for the object, nor for the background. The method is validated by measuring fluid volume of brain phantoms and by comparing our volume assessments on clinical data to those derived from a segmentation controlled by expert physicians. Then we show that a distinction between pathological cases and healthy adult people can be achieved by a linear discriminant analysis on volumes of the ventricular and intracranial subarachnoid spaces.

30 CFR 250.456 - What safe practices must the drilling fluid program follow?

Code of Federal Regulations, 2011 CFR

2011-07-01

... fluid. You must circulate a volume of drilling fluid equal to the annular volume with the drill pipe... fluid volume needed to fill the hole. Both sets of numbers must be posted near the driller's station... warrant. Your tests must conform to industry-accepted practices and include density, viscosity, and gel...

HOW DOES ADDING AND REMOVING LIQUID FROM SOCKET BLADDERS AFFECT RESIDUAL LIMB FLUID VOLUME?

PubMed Central

Sanders, JE; Cagle, JC; Harrison, DS; Myers, TR; Allyn, KJ

2015-01-01

Adding and removing liquid from socket bladders is a means for people with limb loss to accommodate residual limb volume change. Nineteen people with trans-tibial amputation using their regular prosthetic socket fitted with fluid bladders on the inside socket surface underwent cycles of bladder liquid addition and removal. In each cycle, subjects sat, stood, and walked for 90s with bladder liquid added and then sat, stood, and walking for 90s again with the bladder liquid removed. The amount of bladder liquid added was increased in each cycle. Bioimpedance analysis was implemented to measure residual limb fluid volume. Results showed that the preferred bladder liquid volume was 16.8 mL (s.d.8.4), corresponding to 1.7% (s.d.0.8%) of the average socket volume between the bioimpedance voltage-sensing electrodes. Limb fluid volume driven out of the residual limb when bladder liquid was added was typically not recovered upon subsequent bladder liquid removal. Fifteen of nineteen subjects experienced a gradual limb fluid volume loss over the test session. Care should be taken when implementing adjustable socket technologies in people with limb amputation. Reducing socket volume may accentuate limb fluid volume loss. PMID:24203546

Apparatus and Methods for Fluid Storage and Delivery

NASA Technical Reports Server (NTRS)

Parazynski, Scott E. (Inventor); Bue, Grant C. (Inventor); Urban, Kase C. (Inventor); Schaefbauer, Mark E. (Inventor)

2014-01-01

An apparatus and method for storing and delivering fluid to a person comprises, in at least one specific embodiment, a fluid reservoir having an internal volume therein with an opening disposed through a first wall or a second wall of the fluid reservoir and located toward a first end of the fluid reservoir. A first portion of a tube can be exterior to the fluid reservoir and a second portion of the tube can be disposed through the opening and within the internal volume. At least one insulation layer can be disposed about the exterior of the first wall of the fluid reservoir. The second wall of the fluid reservoir can be configured for transferring heat from or to the internal volume or from the person. At least one baffle is disposed within the internal volume and connected to the first wall and the second wall of the fluid reservoir.

Graphene nanoplatelets as high-performance filtration control material in water-based drilling fluids

NASA Astrophysics Data System (ADS)

Ridha, Syahrir; Ibrahim, Arif; Shahari, Radzi; Fonna, Syarizal

2018-05-01

The main objective of this work is to evaluate the effectiveness of graphene nanoplatelets (GNP) as filtration control materials in water based drilling fluids. Three (3) general samples of water based drilling fluids were prepared including basic potassium chloride (KCl) drilling fluids, nanosilica (NS) drilling fluids and GNP drilling fluids. Several concentrations of NS and GNP were dispersed in controlled formulations of water based drilling fluids. Standard API filtration tests were carried out for comparison purposes as well as High Temperature High Pressure (HTHP) filtration tests at 150 °F (∼66 °C), 250 °F (∼121 °C) and 350 °F (∼177 °C) at a fixed 500 (∼3.45MPa) psi to study the filtration trend as a function of temperature. Mud cake samples from several tests were selectively chosen and analyzed under Field Emission Scanning Electron Microscope (FESEM) for its morphology. Results from this work show that nanoparticle concentrations play a factor in filtration ability of colloid materials in water based drilling fluids when studied at elevated temperature. Low temperature filtration, however, shows only small differences in volume in all the drilling fluid samples. 0.1 ppb concentrations of GNP reduced the fluid loss of 350 °F by 4.6 mL as compared to the similar concentration of NS drilling fluids.

Computation of porosity redistribution resulting from thermal convection in slanted porous layers

NASA Astrophysics Data System (ADS)

Gouze, Phillippe; Coudrain-Ribstein, Anne; Bernard, Dominique

1994-01-01

Unlike fluid displacement due to regional hydraulic head, thermoconvetive motions are generally slow. The thermal impacts of such movements are very weak, whereas their chemical impacts may be significant because of their cumulated effects over geologic time. For nonhorizontal thick sedimentary reservoirs, the fluid velocity due to thermal convection can be accurately approximated by an explicit function of the dip of the reservior, the permeability and the difference in thermal conductivity between the aquifer and the confining beds. The latter parameter controls the rotation direction of the flow and, for clastic reservoirs bounded by impervious clayey media, fluid moves up the slope along the caprock layer. As the fluid velocity is small, the major rock-forming minerals control the fluid composition by thermodynamic equilibrium. Thus, whereas the volume of redistributed mineral depends on the volume of water circulated, the localization of porosity enhancement is strongly controlled by the reservoir mineralogy. With realistic values of permeability and layer thickness, several per cent of secondary porosity per million years can be created or lost at shallow depth (less than 2 km), depending on the chlorinity, the set of representative minerals and the temperature. In sandstone resevoirs and high-chlorinity calcarenite resoervoirs, the porosity decreases under the caprock where hydrocarbons can accumulate. In chlorinity calcarenite resevoirs, the porosity decreases under the caprock where hydrocarbons can accumulate. In chloride-depleted carbonate aquifers, the simulataneous control by carbonates, silica and aluminosilicates can produce a decrease of porosity above the bedrock and an enhancement of porosity under the caprock. However, computations show that the quality of the upper part of the reservoir is mainly reduced by the precipitation of silica and clays.

A study of unsteady physiological magneto-fluid flow and heat transfer through a finite length channel by peristaltic pumping.

PubMed

Tripathi, Dharmendra; Bég, O Anwar

2012-08-01

Magnetohydrodynamic peristaltic flows arise in controlled magnetic drug targeting, hybrid haemodynamic pumps and biomagnetic phenomena interacting with the human digestive system. Motivated by the objective of improving an understanding of the complex fluid dynamics in such flows, we consider in the present article the transient magneto-fluid flow and heat transfer through a finite length channel by peristaltic pumping. Reynolds number is small enough and the wavelength to diameter ratio is large enough to negate inertial effects. Analytical solutions for temperature field, axial velocity, transverse velocity, pressure gradient, local wall shear stress, volume flowrate and averaged volume flowrate are obtained. The effects of the transverse magnetic field, Grashof number and thermal conductivity on the flow patterns induced by peristaltic waves (sinusoidal propagation along the length of channel) are studied using graphical plots. The present study identifies that greater pressure is required to propel the magneto-fluid by peristaltic pumping in comparison to a non-conducting Newtonian fluid, whereas, a lower pressure is required if heat transfer is effective. The analytical solutions further provide an important benchmark for future numerical simulations.

Spinning fluids reactor

DOEpatents

Miller, Jan D; Hupka, Jan; Aranowski, Robert

2012-11-20

A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

Structurally Controlled Geothermal Systems in the Central Cascades Arc-Backarc Regime, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wannamaker, Philip E.

The goal of this project has been to analyze available magnetotelluric (MT) geophysical surveys, structural geology based on mapping and LiDAR, and fluid geochemical data, to identify high-temperature fluid upwellings, critically stressed rock volumes, and other evidence of structurally-controlled geothermal resources. Data were to be integrated to create conceptual models of volcanic-hosted geothermal resources along the Central Cascades arc segment, especially in the vicinity of Mt. Jefferson to Three Sisters. LiDAR data sets available at Oregon State University (OSU) allowed detailed structural geology modeling through forest canopy. Copious spring and well fluid chemistries, including isotopes, were modeled using Geo-T andmore » TOUGHREACT software.« less

Fluidic origami cellular structure -- combining the plant nastic movements with paper folding art

NASA Astrophysics Data System (ADS)

Li, Suyi; Wang, K. W.

2015-04-01

By combining the physical principles behind the nastic plant movements and the rich designs of paper folding art, we propose a new class of multi-functional adaptive structure called fluidic origami cellular structure. The basic elements of this structure are fluid filled origami "cells", made by connecting two compatible Miura-Ori stripes along their crease lines. These cells are assembled seamlessly into a three dimensional topology, and their internal fluid pressure or volume are strategically controlled just like in plants for nastic movements. Because of the unique geometry of the Miura-Ori, the relationships among origami folding, internal fluid properties, and the crease bending are intricate and highly nonlinear. Fluidic origami can exploit such relationships to provide multiple adaptive functions concurrently and effectively. For example, it can achieve actuation or morphing by actively changing the internal fluid volume, and stillness tuning by constraining the fluid volume. Fluidic origami can also be bistable because of the nonlinear correlation between folding and crease material bending, and such bistable character can be altered significantly by fluid pressurization. These functions are natural and essential companions with respect to each other, so that fluidic origami can holistically exhibit many attractive characteristics of plants and deliver rapid and efficient actuation/morphing while maintaining a high structural stillness. The purpose of this paper is to introduce the design and working principles of the fluidic origami, as well as to explore and demonstrate its performance potential.

Development of an accurate fluid management system for a pediatric continuous renal replacement therapy device

PubMed Central

SANTHANAKRISHNAN, ARVIND; NESTLE, TRENT T.; MOORE, BRIAN L.; YOGANATHAN, AJIT P.; PADEN, MATTHEW L.

2013-01-01

Acute kidney injury is common in critically ill children and renal replacement therapies provide a life saving therapy to a subset of these children. However, there is no Food and Drug Administration approved device to provide pediatric continuous renal replacement therapy (CRRT). Consequently, clinicians adapt approved adult CRRT devices for use in children due to lack of safer alternatives. Complications occur using adult CRRT devices in children due to inaccurate fluid balance (FB) between the volumes of ultrafiltrate (UF) removed and replacement fluid (RF) delivered. We demonstrate the design and validation of a pediatric fluid management system for obtaining accurate instantaneous and cumulative FB. Fluid transport was achieved via multiple novel pulsatile diaphragm pumps. The conservation of volume principle leveraging the physical property of fluid incompressibility along with mechanical coupling via a crankshaft was used for FB. Accuracy testing was conducted in vitro for 8-hour long continuous operation of the coupled UF and RF pumps. The mean cumulative FB error was <1% across filtration flows from 300 mL/hour to 3000 mL/hour. This approach of FB control in a pediatric specific CRRT device would represent a significant accuracy improvement over currently used clinical implementations. PMID:23644618

Characterization of fluid physics effects on cardiovascular response to microgravity (G-572)

NASA Technical Reports Server (NTRS)

Pantalos, George M.; Sharp, M. Keith; Woodruff, Stewart J.; Lorange, Richard D.; Bennett, Thomas E.; Sojka, Jan J.; Lemon, Mark W.

1993-01-01

The recognition and understanding of cardiovascular adaptation to spaceflight has experienced substantial advancement in the last several years. In-flight echocardiographic measurements of astronaut cardiac function on the Space Shuttle have documented a 15 percent reduction in both left ventricular volume index and stroke volume with a compensatory increase in heart rate to maintain cardiac output. To date, the reduced cardiac size and stroke volume have been presumed to be the consequence of the reduction in circulating fluid volume following diuresis and other physiological processes to reduce blood volume within a few days after orbital insertion. However, no specific mechanism for the reduced stroke volume has been elucidated. The following investigation proposes the use of a hydraulic model of the cardiovascular system to examine the possibility that the observed reduction in stroke volume may, in part, be related to fluid physics effects on heart function. The automated model is being prepared to fly as a GAS payload. The experimental apparatus consists of a pneumatically actuated, elliptical artificial ventricle connected to a closed-loop, hydraulic circuit with compliance and resistance elements to create physiologic pressure and flow conditions. The ventricle is instrumented with high-fidelity, acceleration-insensitive, catheter-tip pressure transducers (Millar Instruments) in the apex and base to determine the instantaneous ventricular pressures and (delta)P(sub LV) across the left ventricle (LVP(sub apex)-LVP(sub base). The ventricle is also instrumented with a flow probe and pressure transducers immediately upstream of the inflow valve and downstream of the outflow valve. The experiment will be microprocessor controlled with analog signals stored on the FM data tape recorder. By varying the circulating fluid volume, ventricular function can be determined for varying preload pressures with fixed afterload pressure. Pilot experiments on board the NASA KC-135 aircraft have demonstrated proof-of-concept and provided early support for the proposed hypothesis. A review of the pilot experiments and developmental progress on the GAS version of this experiment will be presented.

The effect of type and volume of fluid hydration on labor duration of nulliparous women: a randomized controlled trial.

PubMed

Garmi, Gali; Zuarez-Easton, Sivan; Zafran, Noah; Ohel, Iris; Berkovich, Ilanit; Salim, Raed

2017-06-01

Type and volume of fluid administered for intrapartum maintenance had been reported to differently affect labor length, delivery mode, and cord artery pH and glucose level. We aimed to compare the effect of three different fluid regimens on labor duration. In a randomized trial, healthy nulliparous in labor were randomized into one of three intravenous fluid regimens: group 1, the reference group, lactated Ringer's solution infused at a rate of 125 mL/h; group 2, lactated Ringer's solution infused at a rate of 250 mL/h; group 3, 0.9% saline solution boosted with 5% glucose, infused at a rate of 125 mL/h. The primary outcome was labor length from enrollment until delivery. Between December 2010 and July 2015, 300 women were randomized to one of the three groups. Demographic and baseline obstetric characteristics were comparable between the groups. There was no significant difference in the time from enrollment to delivery (p = 0.62). Furthermore, there were no significant differences in second stage duration (p = 0.73), mode of delivery (p = 0.21), cord artery pH and glucose level between the groups. Increasing the intravenous volume of lactated Ringer's solution or substituting to fluid containing 5% glucose solution does not affect labor length. ClinicalTrials.gov, http://www.clinicaltrials.gov , NCT01242293.

Supplemental Intravenous Crystalloid Administration Does Not Reduce the Risk of Surgical Wound Infection

PubMed Central

Kabon, Barbara; Akça, Ozan; Taguchi, Akiko; Nagele, Angelika; Jebadurai, Ratnaraj; Arkilic, Cem F.; Sharma, Neeru; Ahluwalia, Arundhathi; Galandiuk, Susan; Fleshman, James; Sessler, Daniel I.; Kurz, Andrea

2005-01-01

Wound perfusion and oxygenation are important determinants of the development of postoperative wound infections. Supplemental fluid administration significantly increases tissue oxygenation in surrogate wounds in the subcutaneous tissue of the upper arm in perioperative surgical patients. We tested the hypothesis that supplemental fluid administration during and after elective colon resections decreases the incidence of postoperative wound infections. Patients undergoing open colon resection were randomly assigned to small (n=124, 8 mL·kg-1·h-1) or large volume (n=129, 16-18 mL·kg-1·h-1) fluid management. Our major outcomes were two distinct criteria for diagnosis of surgical wound infections: 1) purulent exudate combined with a culture positive for pathogenic bacteria and 2) Center for Disease Control criteria for diagnosis of surgical wound infections. All wound infections diagnosed using either criterion by a blinded observer in the 15 days following surgery were considered in the analysis. Wound healing was evaluated with the ASEPSIS scoring system. Of the patients given small fluid administration, 14 had surgical wound infections; 11 given large fluid therapy had infections, P=0.46. ASEPSIS wound healing scores were similar in both groups: 7±16 (small volume) vs. 8±14 (large volume), P=0.70. Our results suggest that supplemental hydration in the range tested does not impact wound infection rate. PMID:16244030

Gastric Fluid Volume Change After Oral Rehydration Solution Intake in Morbidly Obese and Normal Controls: A Magnetic Resonance Imaging-Based Analysis.

PubMed

Shiraishi, Toshie; Kurosaki, Dai; Nakamura, Mitsuyo; Yazaki, Taiji; Kobinata, Satomi; Seki, Yosuke; Kasama, Kazunori; Taniguchi, Hideki

2017-04-01

Although preoperative fluid intake 2 hours before anesthesia is generally considered safe, there are concerns about delayed gastric emptying in obese subjects. In this study, the gastric fluid volume (GFV) change in morbidly obese subjects was investigated after ingesting an oral rehydration solution (ORS) and then compared with that in nonobese subjects. GFV change over time after the ingestion of 500 mL of ORS containing 2.5% carbohydrate (OS-1) was measured in 10 morbidly obese subjects (body mass index [BMI], >35) scheduled for bariatric surgery and 10 nonobese (BMI, 19-24) using magnetic resonance imaging. After 9 hours of fasting, magnetic resonance imaging scans were performed at preingestion, 0 min (just after ingestion), and every 30 minutes up to 120 minutes. GFV values were compared between morbidly obese and control groups and also between preingestion and postingestion time points. The morbidly obese group had a significantly higher body weight and BMI than the control group (mean body weight and BMI in morbidly obese, 129.6 kg and 46.3 kg/m, respectively; control, 59.5 kg and 21.6 kg/m, respectively). GFV was significantly higher in the morbidly obese subjects compared with the control group at preingestion (73 ± 30.8 mL vs 31 ± 19.9 mL, P = .001) and at 0 minutes after ingestion (561 ± 30.8 mL vs 486 ± 42.8 mL; P < .001). GFV declined rapidly in both groups and reached fasting baseline levels by 120 minutes (morbidly obese, 50 ± 29.5 mL; control, 30 ± 11.6 mL). A significant correlation was observed between preingestion residual GFV and body weight (r = .66; P = .001). Morbidly obese subjects have a higher residual gastric volume after 9 hours of fasting compared with subjects with a normal BMI. However, no differences were observed in gastric emptying after ORS ingestion in the 2 populations, and GFVs reached baseline within 2 hours after ORS ingestion. Further studies are required to confirm whether the preoperative fasting and fluid management that are recommended for nonobese patients could also be applied to morbidly obese patients.

Fluid overload in the ICU: evaluation and management.

PubMed

Claure-Del Granado, Rolando; Mehta, Ravindra L

2016-08-02

Fluid overload is frequently found in acute kidney injury patients in critical care units. Recent studies have shown the relationship of fluid overload with adverse outcomes; hence, manage and optimization of fluid balance becomes a central component of the management of critically ill patients. In critically ill patients, in order to restore cardiac output, systemic blood pressure and renal perfusion an adequate fluid resuscitation is essential. Achieving an appropriate level of volume management requires knowledge of the underlying pathophysiology, evaluation of volume status, and selection of appropriate solution for volume repletion, and maintenance and modulation of the tissue perfusion. Numerous recent studies have established a correlation between fluid overload and mortality in critically ill patients. Fluid overload recognition and assessment requires an accurate documentation of intakes and outputs; yet, there is a wide difference in how it is evaluated, reviewed and utilized. Accurate volume status evaluation is essential for appropriate therapy since errors of volume evaluation can result in either in lack of essential treatment or unnecessary fluid administration, and both scenarios are associated with increased mortality. There are several methods to evaluate fluid status; however, most of the tests currently used are fairly inaccurate. Diuretics, especially loop diuretics, remain a valid therapeutic alternative. Fluid overload refractory to medical therapy requires the application of extracorporeal therapies. In critically ill patients, fluid overload is related to increased mortality and also lead to several complications like pulmonary edema, cardiac failure, delayed wound healing, tissue breakdown, and impaired bowel function. Therefore, the evaluation of volume status is crucial in the early management of critically ill patients. Diuretics are frequently used as an initial therapy; however, due to their limited effectiveness the use of continuous renal replacement techniques are often required for fluid overload treatment. Successful fluid overload treatment depends on precise assessment of individual volume status, understanding the principles of fluid management with ultrafiltration, and clear treatment goals.

Assessment and Management of Volume Overload and Congestion in Chronic Heart Failure: Can Measuring Blood Volume Provide New Insights?

PubMed

Miller, Wayne L

2017-01-01

Volume overload and fluid congestion remain primary clinical challenges in the assessment and management of patients with chronic heart failure (HF). The pathophysiology of volume regulation is complex, and the simple concept of passive intravascular fluid accumulation is not adequate. The dynamics of interstitial and intravascular fluid compartment interactions and fluid redistribution from venous splanchnic beds to the central pulmonary circulation need to be taken into account in strategies of volume management. Clinical bedside evaluations and right heart hemodynamic assessments can alert of changes in volume status, but only the quantitative measurement of total blood volume can help identify the heterogeneity in plasma volume and red blood cell mass that are features of volume overload in chronic HF. The quantitative assessment of intravascular volume is an effective tool to help guide individualized, appropriate therapy. Not all volume overload is the same, and the measurement of intravascular volume identifies heterogeneity to guide tailored therapy.

Mechanistic Fluid Transport Model to Estimate Gastrointestinal Fluid Volume and Its Dynamic Change Over Time.

PubMed

Yu, Alex; Jackson, Trachette; Tsume, Yasuhiro; Koenigsknecht, Mark; Wysocki, Jeffrey; Marciani, Luca; Amidon, Gordon L; Frances, Ann; Baker, Jason R; Hasler, William; Wen, Bo; Pai, Amit; Sun, Duxin

2017-11-01

Gastrointestinal (GI) fluid volume and its dynamic change are integral to study drug disintegration, dissolution, transit, and absorption. However, key questions regarding the local volume and its absorption, secretion, and transit remain unanswered. The dynamic fluid compartment absorption and transit (DFCAT) model is proposed to estimate in vivo GI volume and GI fluid transport based on magnetic resonance imaging (MRI) quantified fluid volume. The model was validated using GI local concentration of phenol red in human GI tract, which was directly measured by human GI intubation study after oral dosing of non-absorbable phenol red. The measured local GI concentration of phenol red ranged from 0.05 to 168 μg/mL (stomach), to 563 μg/mL (duodenum), to 202 μg/mL (proximal jejunum), and to 478 μg/mL (distal jejunum). The DFCAT model characterized observed MRI fluid volume and its dynamic changes from 275 to 46.5 mL in stomach (from 0 to 30 min) with mucus layer volume of 40 mL. The volumes of the 30 small intestine compartments were characterized by a max of 14.98 mL to a min of 0.26 mL (0-120 min) and a mucus layer volume of 5 mL per compartment. Regional fluid volumes over 0 to 120 min ranged from 5.6 to 20.38 mL in the proximal small intestine, 36.4 to 44.08 mL in distal small intestine, and from 42 to 64.46 mL in total small intestine. The DFCAT model can be applied to predict drug dissolution and absorption in the human GI tract with future improvements.

Lubrication Flows.

ERIC Educational Resources Information Center

Papanastasiou, Tasos C.

1989-01-01

Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

Cochlear fluid space dimensions for six species derived from reconstructions of three-dimensional magnetic resonance images.

PubMed

Thorne, M; Salt, A N; DeMott, J E; Henson, M M; Henson, O W; Gewalt, S L

1999-10-01

To establish the dimensions and volumes of the cochlear fluid spaces. Fluid space volumes, lengths, and cross-sectional areas were derived for the cochleas from six species: human, guinea pig, bat, rat, mouse, and gerbil. Three-dimensional reconstructions of the fluid spaces were made from magnetic resonance microscopy (MRM) images. Consecutive serial slices composed of isotropic voxels (25 microm3) representing the entire volume of fixed, isolated cochleas were obtained. The boundaries delineating the fluid spaces, including Reissner's membrane, were resolved for all specimens, except for the human, in which Reissner's membrane was not consistently resolved. Three-dimensional reconstructions of the endolymphatic and perilymphatic fluid spaces were generated. Fluid space length and variation of cross-sectional area with distance were derived by an algorithm that followed the midpoint of the space along the length of the spiral. The total volume of each fluid space was derived from a voxel count for each specimen. Length, volume, and cross-sectional areas are provided for six species. In all cases, the length of the endolymphatic fluid space was consistently longer than that of either perilymphatic scala, primarily as a result of a greater radius of curvature. For guinea pig specimens, the measured volumes of the fluid spaces were considerably lower than those suggested by previous reports based on histological data. The quantification of cochlear fluid spaces provided by this study will enable the more accurate calculation of drug and other solute movements in fluids of the inner ear during experimental or clinical manipulations.

CMC blade with pressurized internal cavity for erosion control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Crespo, Andres; Goike, Jerome Walter

A ceramic matrix composite blade for use in a gas turbine engine having an airfoil with leading and trailing edges and pressure and suction side surfaces, a blade shank secured to the lower end of each airfoil, one or more interior fluid cavities within the airfoil having inlet flow passages at the lower end which are in fluid communication with the blade shank, one or more passageways in the blade shank corresponding to each one of the interior fluid cavities and a fluid pump (or compressor) that provides pressurized fluid (nominally cool, dry air) to each one of the interiormore » fluid cavities in each airfoil. The fluid (e.g., air) is sufficient in pressure and volume to maintain a minimum fluid flow to each of the interior fluid cavities in the event of a breach due to foreign object damage.« less

Fluid transport in reaction induced fractures

NASA Astrophysics Data System (ADS)

Ulven, Ole Ivar; Sun, WaiChing; Malthe-Sørenssen, Anders

2015-04-01

The process of fracture formation due to a volume increasing chemical reaction has been studied in a variety of different settings, e.g. weathering of dolerites by Røyne et al. te{royne}, serpentinization and carbonation of peridotite by Rudge et al. te{rudge} and replacement reactions in silica-poor igneous rocks by Jamtveit et al. te{jamtveit}. It is generally assumed that fracture formation will increase the net permeability of the rock, and thus increase the reactant transport rate and subsequently the total rate of material conversion, as summarised by Kelemen et al. te{kelemen}. Ulven et al. te{ulven_1} have shown that for fluid-mediated processes the ratio between chemical reaction rate and fluid transport rate in bulk rock controls the fracture pattern formed, and Ulven et al. te{ulven_2} have shown that instantaneous fluid transport in fractures lead to a significant increase in the total rate of the volume expanding process. However, instantaneous fluid transport in fractures is clearly an overestimate, and achievable fluid transport rates in fractures have apparently not been studied in any detail. Fractures cutting through an entire domain might experience relatively fast advective reactant transport, whereas dead-end fractures will be limited to diffusion of reactants in the fluid, internal fluid mixing in the fracture or capillary flow into newly formed fractures. Understanding the feedback process between fracture formation and permeability changes is essential in assessing industrial scale CO2 sequestration in ultramafic rock, but little is seemingly known about how large the permeability change will be in reaction-induced fracturing. In this work, we study the feedback between fracture formation during volume expansion and fluid transport in different fracture settings. We combine a discrete element model (DEM) describing a volume expanding process and the related fracture formation with different models that describe the fluid transport in the fractures. This provides new information on how much reaction induced fracturing might accelerate a volume expanding process. Jamtveit, B, Putnis, C. V., and Malthe-Sørenssen, A., ``Reaction induced fracturing during replacement processes,'' Contrib. Mineral Petrol. 157, 2009, pp. 127 - 133. Kelemen, P., Matter, J., Streit, E. E., Rudge, J. F., Curry, W. B., and Blusztajn, J., ``Rates and Mechanisms of Mineral Carbonation in Peridotite: Natural Processes and Recipes for Enhanced, in situ CO2 Capture and Storage,'' Annu. Rev. Earth Planet. Sci. 2011. 39:545 - 76. Rudge, J. F., Kelemen, P. B., and Spiegelman, M., ``A simple model of reaction induced cracking applied to serpentinization and carbonation of peridotite,'' Earth Planet. Sc. Lett. 291, Issues 1-4, 2010, pp. 215 - 227. Røyne, A., Jamtveit, B., and Malthe-Sørenssen, A., ``Controls on rock weathering rates by reaction-induced hierarchial fracturing,'' Earth Planet. Sc. Lett. 275, 2008, pp. 364 - 369. Ulven, O. I., Storheim, H., Austrheim, H., and Malthe-Sørenssen, A. ``Fracture initiation during volume increasing reactions in rocks and applications for CO2 sequestration'', Earth Planet. Sc. Lett. 389C, 2014, pp. 132 - 142, doi:10.1016/j.epsl.2013.12.039. Ulven, O. I., Jamtveit, B., and Malthe-Sørenssen, A., ``Reaction-driven fracturing of porous rock'', J. Geophys. Res. Solid Earth 119, 2014, doi:10.1002/2014JB011102.

Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

NASA Astrophysics Data System (ADS)

Dolejš, David; Wagner, Thomas

2008-01-01

We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic alteration commencing with alkali-feldspar breakdown and leading to potassic, phyllic and argillic assemblages; this is associated with reduction and iron metasomatism as observed in nature and (3) interaction with a multicomponent fluid at 600 °C produces sodic-calcic metasomatism. Na, Ca and Fe are the most mobile elements whereas immobility of Al is limited by f/r ∼ 400. All simulations predict a volume decrease by 3.4-5.4%, i.e., porosity formation at f/r < 30. At higher fluid/rock ratios simulation (2) produces a substantial volume increase (59%) due to mineral precipitation, whereas simulation (3) predicts a volume decrease by 49% at the advanced albitization-desilication stage. Volume changes closely correlate with mass changes of SiO2 and are related to silica solubility in fluids. The combined effects of oxygen fugacity, fluid acidity and pH for breakdown of aqueous metal complexes and precipitation of ore minerals were evaluated by means of reduced activity products. Sharp increases in saturation indexes for oxidative breakdown occur at each alteration zone whereas reductive breakdown or involvement of other chloride complexes favor precipitation at high fluid/rock ratios only. Calculations of multicomponent aqueous-solid equilibria at high temperatures and pressures are able to accurately predict rock mineralogy and fluid chemistry and are applicable to diverse reactive flow processes in the Earth's crust.

Numerical simulation of water evaporation inside vertical circular tubes

NASA Astrophysics Data System (ADS)

Ocłoń, Paweł; Nowak, Marzena; Majewski, Karol

2013-10-01

In this paper the results of simplified numerical analysis of water evaporation in vertical circular tubes are presented. The heat transfer in fluid domain (water or wet steam) and solid domain (tube wall) is analyzed. For the fluid domain the temperature field is calculated solving energy equation using the Control Volume Method and for the solid domain using the Finite Element Method. The heat transfer between fluid and solid domains is conjugated using the value of heat transfer coefficient from evaporating liquid to the tube wall. It is determined using the analytical Steiner-Taborek correlation. The pressure changes in fluid are computed using Friedel model.

Active mixing of complex fluids at the microscale

DOE PAGES

Ober, Thomas J.; Foresti, Daniele; Lewis, Jennifer A.

2015-09-22

Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. As a result, active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks withmore » programmable control of local composition.« less

Active mixing of complex fluids at the microscale

PubMed Central

Ober, Thomas J.; Foresti, Daniele; Lewis, Jennifer A.

2015-01-01

Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition. PMID:26396254

Perioperative fluid management: comparison of high, medium and low fluid volume on tissue oxygen pressure in the small bowel and colon.

PubMed

Hiltebrand, L B; Pestel, G; Hager, H; Ratnaraj, J; Sigurdsson, G H; Kurz, A

2007-11-01

Insufficient blood flow and oxygenation in the intestinal tract is associated with increased incidence of postoperative complications after bowel surgery. High fluid volume administration may prevent occult regional hypoperfusion and intestinal tissue hypoxia. We tested the hypothesis that high intraoperative fluid volume administration increases intestinal wall tissue oxygen pressure during laparotomy. In all, 27 pigs were anaesthetized, ventilated and randomly assigned to one of the three treatment groups (n = 9 in each) receiving low (3 mL kg-1 h-1), medium (7 mL kg-1 h-1) or high (20 mL kg-1 h-1) fluid volume treatment with lactated Ringer's solution. All animals received 30% and 100% inspired oxygen in random order. Cardiac index was measured with thermodilution and tissue oxygen pressure with a micro-oximetry system in the jejunum and colon wall and subcutaneous tissue. Groups receiving low and medium fluid volume treatment had similar systemic haemodynamics. The high fluid volume group had significantly higher mean arterial pressure, cardiac index and subcutaneous tissue oxygenation. Tissue oxygen pressures in the jejunum and colon were comparable in all three groups. The three different fluid volume regimens tested did not affect tissue oxygen pressure in the jejunum and colon, suggesting efficient autoregulation of intestinal blood flow in healthy subjects undergoing uncomplicated abdominal surgery.

Refractory Hypertension Is not Attributable to Intravascular Fluid Retention as Determined by Intracardiac Volumes.

PubMed

Velasco, Alejandro; Siddiqui, Mohammed; Kreps, Eric; Kolakalapudi, Pavani; Dudenbostel, Tanja; Arora, Garima; Judd, Eric K; Prabhu, Sumanth D; Lloyd, Steven G; Oparil, Suzanne; Calhoun, David A

2018-06-04

Refractory hypertension (RfHTN) is an extreme phenotype of antihypertensive treatment failure defined as lack of blood pressure control with ≥5 medications, including a long-acting thiazide and a mineralocorticoid receptor antagonist. RfHTN is a subgroup of resistant hypertension (RHTN), which is defined as blood pressure >135/85 mm Hg with ≥3 antihypertensive medications, including a diuretic. RHTN is generally attributed to persistent intravascular fluid retention. It is unknown whether alternative mechanisms are operative in RfHTN. Our objective was to determine whether RfHTN is characterized by persistent fluid retention, indexed by greater intracardiac volumes determined by cardiac magnetic resonance when compared with controlled RHTN patients. Consecutive patients evaluated in our institution with RfHTN and controlled RHTN were prospectively enrolled. Exclusion criteria included advanced chronic kidney disease and masked or white coat hypertension. All enrolled patients underwent biochemical testing and cardiac magnetic resonance. The RfHTN group (n=24) was younger (mean age, 51.7±8.9 versus 60.6±11.5 years; P =0.003) and had a greater proportion of women (75.0% versus 43%; P =0.02) compared with the controlled RHTN group (n=30). RfHTN patients had a greater left ventricular mass index (88.3±35.0 versus 54.6±12.5 g/m 2 ; P <0.001), posterior wall thickness (10.1±3.1 versus 7.7±1.5 mm; P =0.001), and septal wall thickness (14.5±3.8 versus 10.0±2.2 mm; P <0.001). There was no difference in B-type natriuretic peptide levels and left atrial or ventricular volumes. Diastolic dysfunction was noted in RfHTN. Our findings demonstrate greater left ventricular hypertrophy without chamber enlargement in RfHTN, suggesting that antihypertensive treatment failure is not attributable to intravascular volume retention. © 2018 American Heart Association, Inc.

Role of atrial natriuretic peptide in systemic responses to acute isotonic volume expansion

NASA Technical Reports Server (NTRS)

Watenpaugh, Donald E.; Yancy, Clyde W.; Buckey, Jay C.; Lane, Lynda D.; Hargens, Alan R.; Blomqvist, C. G.

1992-01-01

A hypothesis is proposed that a temporal relationship exists between increases in cardiac filling pressure and plasma artrial natriuretic peptide (ANP) concentration and also between ANP elevation and vasodilation, fluid movement from plasma to interstitium, and increased urine volume (UV). To test the hypothesis, 30 ml/kg isotonic saline were infused in supine male subjects over 24 min and responses were monitored for 3 h postinfusion. Results show that at end infusion, mean arterial pressure (RAP), heart rate and plasma volume exhibited peak increases of 146, 23, and 27 percent, respectively. Mean plasma ANP and UV peaked (45 and 390 percent, respectively) at 30 min postinfusion. Most cardiovascular variables had returned toward control levels by 1 h postinfusion, and net reabsorption of extravascular fluid ensued. It is concluded that since ANP was not significantly increased until 30 min postinfusion, factors other than ANP initiate responses to intravascular fluid loading. These factors include increased vascular pressures, baroreceptor-mediated vasolidation, and hemodilution of plasma proteins. ANP is suggested to mediate, in part, the renal response to saline infusion.

Non-Invasive Electromagnetic Skin Patch Sensor to Measure Intracranial Fluid–Volume Shifts

PubMed Central

Griffith, Jacob; Cluff, Kim; Eckerman, Brandon; Aldrich, Jessica; Becker, Ryan; Moore-Jansen, Peer; Patterson, Jeremy

2018-01-01

Elevated intracranial fluid volume can drive intracranial pressure increases, which can potentially result in numerous neurological complications or death. This study’s focus was to develop a passive skin patch sensor for the head that would non-invasively measure cranial fluid volume shifts. The sensor consists of a single baseline component configured into a rectangular planar spiral with a self-resonant frequency response when impinged upon by external radio frequency sweeps. Fluid volume changes (10 mL increments) were detected through cranial bone using the sensor on a dry human skull model. Preliminary human tests utilized two sensors to determine feasibility of detecting fluid volume shifts in the complex environment of the human body. The correlation between fluid volume changes and shifts in the first resonance frequency using the dry human skull was classified as a second order polynomial with R2 = 0.97. During preliminary and secondary human tests, a ≈24 MHz and an average of ≈45.07 MHz shifts in the principal resonant frequency were measured respectively, corresponding to the induced cephalad bio-fluid shifts. This electromagnetic resonant sensor may provide a non-invasive method to monitor shifts in fluid volume and assist with medical scenarios including stroke, cerebral hemorrhage, concussion, or monitoring intracranial pressure. PMID:29596338

Research into the Physiology of Cerebrospinal Fluid Reaches a New Horizon: Intimate Exchange between Cerebrospinal Fluid and Interstitial Fluid May Contribute to Maintenance of Homeostasis in the Central Nervous System

PubMed Central

MATSUMAE, Mitsunori; SATO, Osamu; HIRAYAMA, Akihiro; HAYASHI, Naokazu; TAKIZAWA, Ken; ATSUMI, Hideki; SORIMACHI, Takatoshi

2016-01-01

Cerebrospinal fluid (CSF) plays an essential role in maintaining the homeostasis of the central nervous system. The functions of CSF include: (1) buoyancy of the brain, spinal cord, and nerves; (2) volume adjustment in the cranial cavity; (3) nutrient transport; (4) protein or peptide transport; (5) brain volume regulation through osmoregulation; (6) buffering effect against external forces; (7) signal transduction; (8) drug transport; (9) immune system control; (10) elimination of metabolites and unnecessary substances; and finally (11) cooling of heat generated by neural activity. For CSF to fully mediate these functions, fluid-like movement in the ventricles and subarachnoid space is necessary. Furthermore, the relationship between the behaviors of CSF and interstitial fluid in the brain and spinal cord is important. In this review, we will present classical studies on CSF circulation from its discovery over 2,000 years ago, and will subsequently introduce functions that were recently discovered such as CSF production and absorption, water molecule movement in the interstitial space, exchange between interstitial fluid and CSF, and drainage of CSF and interstitial fluid into both the venous and the lymphatic systems. Finally, we will summarize future challenges in research. This review includes articles published up to February 2016. PMID:27245177

Shuttle cryogenic supply system optimization study. Volume 3: Technical report, section 10, 11 and 12

NASA Technical Reports Server (NTRS)

1973-01-01

The evaluation of candidate cryogenic fuel systems for space shuttle vehicles is discussed. A set of guidelines was used to establish a matrix of possible combinations for the integration of potential cryogenic systems. The various concepts and combinations which resulted from the integration efforts are described. The parameters which were considered in developing the matrix are: (1) storage of cryogenic materials, (2) fuel lines, (3) tank pressure control, (4) thermal control, (5) fluid control, and (6) fluid conditioning. Block diagrams and drawings of the candidate systems are provided. Performance predictions for the systems are outlined in tables of data.

Medication and volume delivery by gravity-driven micro-drip intravenous infusion: potential variations during "wide-open" flow.

PubMed

Pierce, Eric T; Kumar, Vikram; Zheng, Hui; Peterfreund, Robert A

2013-03-01

Gravity-driven micro-drip infusion sets allow control of medication dose delivery by adjusting drops per minute. When the roller clamp is fully open, flow in the drip chamber can be a continuous fluid column rather than discrete, countable, drops. We hypothesized that during this "wide-open" state, drug delivery becomes dependent on factors extrinsic to the micro-drip set and is therefore difficult to predict. We conducted laboratory experiments to characterize volume delivery under various clinically relevant conditions of wide-open flow in an in vitro laboratory model. A micro-drip infusion set, plugged into a bag of normal saline, was connected to a high-flow stopcock at the distal end. Vertically oriented IV catheters (gauges 14-22) were connected to the stopcock. The fluid meniscus height in the bag was fixed (60-120 cm) above the outflow point. The roller clamp on the infusion set was in fully open position for all experiments resulting in a continuous column of fluid in the drip chamber. Fluid volume delivered in 1 minute was measured 4 times with each condition. To model resistive effects of carrier flow, volumetric infusion pumps were used to deliver various flow rates of normal saline through a carrier IV set into which a micro-drip infusion was "piggybacked." We also compared delivery by micro-drip infusion sets from 3 manufacturers. The volume of fluid delivered by gravity-driven infusion under wide-open conditions (continuous fluid column in drip chamber) varied 2.9-fold (95% confidence interval, 2.84-2.96) depending on catheter size and fluid column height. Total model resistance of the micro-drip with stopcock and catheter varied with flow rate. Volume delivered by the piggybacked micro-drip decreased up to 29.7% ± 0.8% (mean ± SE) as the carrier flow increased from 0 to 1998 mL/min. Delivery characteristics of the micro-drip infusion sets from 3 different manufacturers were similar. Laboratory simulation of clinical situations with gravity-driven micro-drip infusion sets under wide-open flow conditions revealed that infusion rate (drug and/or volume delivery) can vary widely depending on extrinsic factors including catheter size, fluid column height, and carrier flow. The variable resistance implies nonlaminar flow in the micro-drip model that cannot be easily predicted mathematically. These findings support the use of mechanical pumps instead of gravity-driven micro-drips to enhance the precision and safety of IV infusions, especially for vasoactive drugs.

Universal scaling of permeability through the granular-to-continuum transition

NASA Astrophysics Data System (ADS)

Wadsworth, F. B.; Scheu, B.; Heap, M. J.; Kendrick, J. E.; Vasseur, J.; Lavallée, Y.; Dingwell, D. B.

2015-12-01

Magmas fragment forming a transiently granular material, which can weld back to a fluid-continuum. This process results in dramatic changes in the gas-volume fraction of the material, which impacts the gas permeability. We collate published data for the gas-volume fraction and permeability of volcanic and synthetic materials which have undergone this process to different amounts and note that in all cases there exists a discontinuity in the relationship between these two properties. By discriminating data for which good microstructural information are provided, we use simple scaling arguments to collapse the data in both the still-granular, high gas-volume fraction regime and the fluid-continuum low gas-volume fraction regime such that a universal description can be achieved. We use this to argue for the microstructural meaning of the well-described discontinuity between gas-permeability and gas-volume fraction and to infer the controls on the position of this transition between dominantly granular and dominantly fluid-continuum material descriptions. As a specific application, we consider the transiently granular magma transported through and deposited in fractures in more-coherent magmas, thought to be a primary degassing pathway in high viscosity systems. We propose that our scaling coupled with constitutive laws for densification can provide insights into the longevity of such degassing channels, informing sub-surface pressure modelling at such volcanoes.

Energy-efficient MRF clutch avoiding no-load losses

NASA Astrophysics Data System (ADS)

Güth, Dirk; Schamoni, Markus; Maas, Jürgen

2013-04-01

A challenge opposing a commercial use of actuators like brakes and clutches based on magnetorheological fluids (MRF) are durable no-load losses. A complete torque-free separation of these actuators is inherently not yet possible due to the permanent liquid intervention for the fluid engaging parts. Especially for applications with high rotational speeds up to some thousand RPM, this drawback of MRF actuators is not acceptable. In this paper, a novel approach will be presented that allows a controlled movement of the MRF from a torque-transmitting volume of the shear gap into an inactive volume of the shear gap, enabling a complete separation of the fluid engaging surfaces. This behavior is modeled for a novel clutch design by the use of the ferrohydrodynamics and therefore simulations are performed to investigate the transitions between engaged and idle mode. Measurements performed with a realized clutch show that the viscous induced drag torque can be reduced significantly.

The relationship between nocturnal polyuria and the distribution of body fluid: assessment by bioelectric impedance analysis.

PubMed

Torimoto, Kazumasa; Hirayama, Akihide; Samma, Shoji; Yoshida, Katsunori; Fujimoto, Kiyohide; Hirao, Yoshihiko

2009-01-01

Increased nocturnal urinary volume is closely associated with nocturia. We investigated the relationship between nocturnal polyuria and the variation of body fluid distribution during the daytime using bioelectric impedance analysis. A total of 34 men older than 60 years were enrolled in this study. A frequency volume chart was recorded. Nocturnal polyuria was defined as a nocturnal urine volume per 24-hour production of greater than 0.35 (the nocturnal polyuria index). Bioelectric impedance analysis was performed 4 times daily at 8 and 11 a.m., and 5 and 9 p.m. using an InBody S20 body composition analyzer (BioSpace, Seoul, Korea). A significant difference was found in mean +/- SEM 24-hour urine production per fat-free mass between the groups with and without nocturnal polyuria (17.8 +/- 1.4 vs 7.7 +/- 0.9 ml/kg). The increase in fluid in the legs compared with the volume at 8 a.m. was significantly larger at 5 p.m., while there was no difference in the arms or trunk. Nocturnal urine volume significantly correlated with the difference in fluid volume in the legs (r = 0.527, p = 0.0019) and extracellular fluid volume (r = 0.3844, p = 0.0248) between the volumes at 8 a.m. and 9 p.m. Overproduction of urine per fat-free mass leads to nocturnal polyuria. Extracellular fluid accumulates as edema in the legs during the day in patients with nocturnal polyuria. The volume of accumulated extracellular fluid correlates with nocturnal urine volume. We suggest that leg edema is the source of nocturnal urine volume and decreasing edema may cure nocturnal polyuria.

Understanding the heterogeneity in volume overload and fluid distribution in decompensated heart failure is key to optimal volume management: role for blood volume quantitation.

PubMed

Miller, Wayne L; Mullan, Brian P

2014-06-01

This study sought to quantitate total blood volume (TBV) in patients hospitalized for decompensated chronic heart failure (DCHF) and to determine the extent of volume overload, and the magnitude and distribution of blood volume and body water changes following diuretic therapy. The accurate assessment and management of volume overload in patients with DCHF remains problematic. TBV was measured by a radiolabeled-albumin dilution technique with intravascular volume, pre-to-post-diuretic therapy, evaluated at hospital admission and at discharge. Change in body weight in relation to quantitated TBV was used to determine interstitial volume contribution to total fluid loss. Twenty-six patients were prospectively evaluated. Two patients had normal TBV at admission. Twenty-four patients were hypervolemic with TBV (7.4 ± 1.6 liters) increased by +39 ± 22% (range, +9.5% to +107%) above the expected normal volume. With diuresis, TBV decreased marginally (+30 ± 16%). Body weight declined by 6.9 ± 5.2 kg, and fluid intake/fluid output was a net negative 8.4 ± 5.2 liters. Interstitial compartment fluid loss was calculated at 6.2 ± 4.0 liters, accounting for 85 ± 15% of the total fluid reduction. TBV analysis demonstrated a wide range in the extent of intravascular overload. Dismissal measurements revealed marginally reduced intravascular volume post-diuretic therapy despite large reductions in body weight. Mobilization of interstitial fluid to the intravascular compartment with diuresis accounted for this disparity. Intravascular volume, however, remained increased at dismissal. The extent, composition, and distribution of volume overload are highly variable in DCHF, and this variability needs to be taken into account in the approach to individualized therapy. TBV quantitation, particularly serial measurements, can facilitate informed volume management with respect to a goal of treating to euvolemia. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms.

PubMed

Umeda, Yasuyuki; Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

2017-01-01

This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.016). The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

Heat pipe temperature control utilizing a soluble gas absorption reservior

NASA Technical Reports Server (NTRS)

Saaski, E. W.

1976-01-01

A new gas-controlled heat pipe design is described which uses a liquid matrix reservior, or sponge, to replace the standard gas reservior. Reservior volume may be reduced by a factor of five to ten for certain gas-liquid combinations, while retaining the same level of temperature control. Experiments with ammonia, butane, and carbon dioxide control gases with methanol working fluid are discussed.

The effect of autologous fibrin tissue adhesive on postoperative cerebrospinal fluid leak in spinal cord surgery: a randomized controlled trial.

PubMed

Nakamura, Hiroshi; Matsuyama, Yukihiro; Yoshihara, Hisatake; Sakai, Yoshihito; Katayama, Yoshito; Nakashima, Shojiro; Takamatsu, Jyunki; Ishiguro, Naoki

2005-07-01

A prospective randomized study evaluating the efficacy of autologous fibrin tissue adhesive for decreasing postoperative cerebrospinal fluid (CSF) leak in spinal cord surgery. To compare postoperative CSF leak in 3 groups (i.e., autologous fibrin tissue adhesive used, commercial fibrin glue used, and no fibrin tissue adhesive used) of patients undergoing spinal surgery who needed dural incision. Spinal cord operations, particularly when dural incision is inevitable, sometimes involve postoperative CSF leak. Because CSF leak is a serious complication, countermeasure is necessary to prevent it after dural suture. Commercial fibrin tissue adhesive was formerly used. Because the possibility of prion infection was widely noticed, commercial fibrin tissue adhesive containing animal components has been used less often. In 13 of 39 cases in which dural incision would be made, 400 mL whole blood was drawn, and autologous fibrin tissue adhesive was made of plasma. Cases were divided into 3 groups: (1) dural closure alone, (2) use of autologous fibrin tissue adhesive after dural closure, and (3) use of commercial fibrin tissue adhesive after dural closure. The primary outcome measure was determined as postoperative (3 days) volume of drainage fluid, and results were analyzed using the analysis of variance. The secondary outcome measure was general blood test, coagulation assay, and plasma fibrinogen, and these were analyzed also using the analysis of variance. There was a significant difference in the primary outcome between the autologous and control groups. No complications such as infection or continuous CSF leak were observed in any case. The mean volume of drainage fluid was 586.2 mL in the group with autologous fibrin tissue adhesive and 1026.1 mL in the group without fibrin tissue adhesive. The volume of drainage fluid was significantly lower in the former group than that in the latter group. There was no statistical difference between the volumes of the group with autologous adhesive and with commercial adhesive (639.2 mL). We used autologous fibrin tissue adhesive as a new sealant after dural closure instead of commercial fibrin tissue adhesive. No definitive CSF leak was observed, and the volume of drainage fluid was significantly lower in the group with autologous fibrin tissue adhesive than that in the group without fibrin tissue adhesive. The use of autologous fibrin tissue adhesive was superior to that of commercial fibrin tissue adhesive in cost.

Pneumatic shutoff and time-delay valve operates at controlled rate

NASA Technical Reports Server (NTRS)

Horning, J. L.; Tomlinson, L. E.

1966-01-01

Shutoff and time delay valve, which incorporates a metering spool that moves at constant velocity under pneumatic pressure and spring compression, increases fluid-flow area at a uniform rate. Diaphragm areas, control cavity volume, and bleed-orifice size may be varied to give any desired combination of time delay and spool travel time.

Action of polysaccharides of similar average mass but differing molecular volume and charge on fluid drainage through synovial interstitium in rabbit knees

PubMed Central

Scott, D; Coleman, P J; Mason, R M; Levick, J R

2000-01-01

Hyaluronan (HA), an anionic polysaccharide of synovial fluid, attenuates fluid loss from joints as joint pressure is raised (‘outflow buffering’). The buffering is thought to depend on the expanded molecular domain of the polymer, which causes reflection by synovial extracellular matrix, leading to flow-dependent concentration polarization. We therefore assessed the effects of polysaccharides of differing average molecular volume and charge. Trans-synovial fluid drainage(Q̇s) was measured at controlled joint fluid pressure (Pj) in knees of anaesthetized rabbits. The joints were infused with polydisperse HA of weight-average mass 2100 kDa (4 mg ml−1, n = 17), with polydisperse neutral dextran of similar average mass (2000 kDa; n = 7) or with Ringer solution vehicle (n = 2). The role of polymer charge was assessed by infusions of neutral or sulphated dextran of average molecular mass 500 kDa (n = 6). When HA was present, Q̇s increased little with pressure, forming a virtual plateau of ∼4 μl min−1 from 10 to 25 cmH2O. Neutral dextran 2000 failed to replicate this effect. Instead, Q̇s increased steeply with Pj, reaching eight times the HA value by 20 cmH2O (P = 0.0001, ANOVA). Dextran 2000 reduced flows in comparison with Ringer solution. Analysis of the aspirated joint fluid showed that 31 ± 0.07 % (s.e.m.) of dextran 2000 in the filtrand was reflected by synovium, compared with ≥ 79 % for HA. The viscometric molecular radius of the dextran, ∼31 nm, was smaller than that of HA (101–181 nm), as was its osmotic pressure. Anionic dextran 500 failed to buffer fluid drainage, but it reduced fluid escape and synovial conductance dQ̇s/dPj more than neutral dextran 500 (P < 0.0001, ANOVA). The anionic charge increased the molecular volume and viscosity of dextran 500. The results support the hypothesis that polymer molecular volume influences its reflection by interstitial matrix and outflow buffering. Polymer charge influences flow through an effect on viscosity and possibly electrostatic interactions with negatively charged interstitial matrix. PMID:11060134

Mapping biological to clinical phenotypes during the development (21 days) and resolution (21 days) of experimental gingivitis.

PubMed

Scott, Ann E; Milward, Mike; Linden, Gerard J; Matthews, John B; Carlile, Monica J; Lundy, Fionnuala T; Naeeni, Mojgan A; Lorraine Martin, S; Walker, Brian; Kinane, Denis; Brock, Gareth R; Chapple, Iain L C

2012-02-01

To characterize and map temporal changes in the biological and clinical phenotype during a 21-day experimental gingivitis study. Experimental gingivitis was induced over 21 days in healthy human volunteers (n = 56), after which normal brushing was resumed (resolution phase). Gingival and plaque indices were assessed. Gingival crevicular fluid was collected from four paired test and contra-lateral control sites in each volunteer during induction (Days 0, 7, 14 and 21) and resolution (Days 28 and 42) of experimental gingivitis. Fluid volumes were measured and a single analyte was quantified from each site-specific, 30s sample. Data were evaluated by analysis of repeated measurements and paired sample tests. Clinical indices and gingival crevicular fluid volumes at test sites increased from Day 0, peaking at Day 21 (test/control differences all p < 0.0001) and decreased back to control levels by Day 28. Levels of four inflammatory markers showed similar patterns, with significant differences between test and control apparent at Day 7 (substance P, cathepsin G, interleukin-1β, elastase: all p < 0.03) and peaking at Day 21 (all p < 0.002). Levels of α-1-antitrypsin showed no pattern. Levels of substance P, cathepsin G, interleukin-1β and neutrophil elastase act as objective biomarkers of gingival inflammation induction and resolution that typically precede phenotypical changes. © 2011 John Wiley & Sons A/S.

High resolution pipette

DOEpatents

Beroz, Justin Douglas; Hart, Anastasios John

2016-06-07

A pipette includes a movable piston and a diaphragm that at least partly defines a fluid chamber enclosing a volume of working fluid. The piston displaces a volumetric amount of the working fluid in the chamber when moved. In response, the diaphragm displaces a smaller volumetric amount of fluid outside the chamber. A deamplification ratio is defined by the ratio of the volume displaced by the diaphragm to the volume displaced by the piston. The deamplification ratio is adjustable by adjusting or changing the diaphragm and/or by adjusting the size of the fluid chamber. The deamplifying pipette enables measuring and dispensing of very small volumes of liquid and is easily adapted to commercially available pipette components. Pipette components such as a pipette tip or adaptor may include a diaphragm to enable deamplification of the nominal volume capacity of a given pipette device.

Numerical study of heat and mass transfer in inertial suspensions in pipes.

NASA Astrophysics Data System (ADS)

Niazi Ardekani, Mehdi; Brandt, Luca

2017-11-01

Controlling heat and mass transfer in particulate suspensions has many important applications such as packed and fluidized bed reactors and industrial dryers. In this work, we study the heat and mass transfer within a suspension of spherical particles in a laminar pipe flow, using the immersed boundary method (IBM) to account for the solid fluid interactions and a volume of fluid (VoF) method to resolve temperature equation both inside and outside of the particles. Tracers that follow the fluid streamlines are considered to investigate mass transfer within the suspension. Different particle volume fractions 5, 15, 30 and 40% are simulated for different pipe to particle diameter ratios: 5, 10 and 15. The preliminary results quantify the heat and mass transfer enhancement with respect to a single-phase laminar pipe flow. We show in particular that the heat transfer from the wall saturates for volume fractions more than 30%, however at high particle Reynolds numbers (small diameter ratios) the heat transfer continues to increase. Regarding the dispersion of tracer particles we show that the diffusivity of tracers increases with volume fraction in radial and stream-wise directions however it goes through a peak at 15% in the azimuthal direction. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

Experimental study of the effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid

NASA Astrophysics Data System (ADS)

yang, P.

2013-12-01

Experimental study of the effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid Ping Yang 1,2, Min-hui Wu2, Xue-wen Zhu2, Tao Deng2, Xue-qing Sun2 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092,China 2. Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China Abstract The process of filtrate loss of low-solids drilling fluid was tested by changing the polyanionic cellulose content in low-solids drilling fluid. The effect of polyanionic cellulose on process of filtrate loss of low-solids drilling fluid was analyzed. The test results showed that when time of filtration is same, the volume of filtrate loss decreases linearly with increasing polyanionic cellulose content. When polyanionic cellulose content is same, the rate of filtrate loss decreases nonlinearly with increasing time and the rate of filtrate loss will reach a stable value.The volume of filtrate loss in 7 to 8 minutes can reaches half of the total volume of filtrate loss. At the same time, the rate of filtrate loss of drilling fluid decreases nonlinearly with increasing viscosity.When the apparent viscosity is between 3.5~4.15 MPa.s, decrease speed of rate of filtrate loss of drilling fluid is quick. The results are helpful for characteristics evaluation of filtrate loss of drilling fluid and control of filtrate loss. Keyword Polyanionic Cellulose,Drilling Fluid,Process of Filtrate Loss Acknowledgments This investigation was supported by the National Natural Science Foundation of China (projects No. 41002093 and 41072205); the Fundamental Research Funds for the Central Universities; the Shanghai Leading Academic Discipline Project (project No. B308), Tongji University; and the Program for Young Excellent Talents, Tongji University. The authors are extremely grateful for the financial support from these five organizations.

Depressed left ventricular performance. Response to volume infusion in patients with sepsis and septic shock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ognibene, F.P.; Parker, M.M.; Natanson, C.

Volume infusion, to increase preload and to enhance ventricular performance, is accepted as initial management of septic shock. Recent evidence has demonstrated depressed myocardial function in human septic shock. We analyzed left ventricular performance during volume infusion using serial data from simultaneously obtained pulmonary artery catheter hemodynamic measurements and radionuclide cineangiography. Critically ill control subjects (n = 14), patients with sepsis but without shock (n = 21), and patients with septic shock (n = 21) had prevolume infusion hemodynamic measurements determined and received statistically similar volumes of fluid resulting in similar increases in pulmonary capillary wedge pressure. There was amore » strong trend (p = 0.004) toward less of a change in left ventricular stroke work index (LVSWI) after volume infusion in patients with sepsis and septic shock compared with control subjects. The LVSWI response after volume infusion was significantly less in patients with septic shock when compared with critically ill control subjects (p less than 0.05). These data demonstrate significantly altered ventricular performance, as measured by LVSWI, in response to volume infusion in patients with septic shock.« less

Fluid displacement from intraluminal thrombus of abdominal aortic aneurysm as a result of uniform compression.

PubMed

van Noort, Kim; Schuurmann, Richte Cl; Wermelink, Bryan; Slump, Cornelis H; Kuijpers, Karel C; de Vries, Jean-Paul Pm

2017-10-01

Objectives The results after aneurysm repair with an endovascular aneurysm sealing (EVAS) system are dependent on the stability of the aneurysm sac and particularly the intraluminal abdominal aortic thrombus (ILT). The postprocedural ILT volume is decreased compared with preprocedural ILT volume in aortic aneurysm patients treated with EVAS. We hypothesize that ILT is not stable in all patients and pressurization of the ILT may result in displacement of fluids from the ILT, no differently than serum is displaced from whole blood when it settles. To date, the mechanism and quantification of fluid displacement from ILT are unknown. Methods The study included 21 patients who underwent elective open abdominal aortic aneurysm repair. The ILT was harvested as a routine procedure during the operation. After excision of a histologic sample of the ILT specimen in four patients, ILT volume was measured and the ILT was compressed in a dedicated compression setup designed to apply uniform compression of 200 mmHg for 5 min. After compression, the volumes of the remaining thrombus and the displaced fluid were measured. Results The median (interquartile-range) of ILT volume before compression was 60 (66) mL, and a median of 5.7 (8.4) mL of fluid was displaced from the ILT after compression, resulting in a median thrombus volume decrease of 11% (10%). Fluid components can be up to 31% of the entire ILT volume. Histologic examination of four ILT specimens showed a reduction of the medial layer of the ILT after compression, which was the result of compression of fluid-containing canaliculi. Conclusions Applying pressure of 200 mmHg to abdominal aortic aneurysm ILT resulted in the displacement of fluid, with a large variation among patients. Fluid displacement may result in decrease of ILT volume during and after EVAS, which might have implications on pre-EVAS volume planning and on stability of the endobags during follow-up which may lead to migration, endoleak or both.

Light Microscopy Module: An On-Orbit Microscope Planned for the Fluids and Combustion Facility on the International Space Station

NASA Technical Reports Server (NTRS)

Doherty, Michael P.; Motil, Susan M.; Snead, John H.; Griffin, DeVon W.

2001-01-01

The Light Microscopy Module (LMM) is planned as a fully remotely controllable on-orbit microscope subrack facility, allowing flexible scheduling and control of fluids and biology experiments within NASA Glenn Research Center's Fluids and Combustion Facility on the International Space Station. Within the Fluids and Combustion Facility, four fluids physics experiments will utilize an instrument built around a light microscope. These experiments are the Constrained Vapor Bubble experiment (Peter C. Wayner of Rensselaer Polytechnic Institute), the Physics of Hard Spheres Experiment-2 (Paul M. Chaikin of Princeton University), the Physics of Colloids in Space-2 experiment (David A. Weitz of Harvard University), and the Low Volume Fraction Colloidal Assembly experiment (Arjun G. Yodh of the University of Pennsylvania). The first experiment investigates heat conductance in microgravity as a function of liquid volume and heat flow rate to determine, in detail, the transport process characteristics in a curved liquid film. The other three experiments investigate various complementary aspects of the nucleation, growth, structure, and properties of colloidal crystals in microgravity and the effects of micromanipulation upon their properties. Key diagnostic capabilities for meeting the science requirements of the four experiments include video microscopy to observe sample features including basic structures and dynamics, interferometry to measure vapor bubble thin film thickness, laser tweezers for colloidal particle manipulation and patterning, confocal microscopy to provide enhanced three-dimensional visualization of colloidal structures, and spectrophotometry to measure colloidal crystal photonic properties.

Fluid therapy and the hypovolemic microcirculation.

PubMed

Gruartmoner, G; Mesquida, J; Ince, Can

2015-08-01

In shock states, optimizing intravascular volume is crucial to promote an adequate oxygen delivery to the tissues. Our current practice in fluid management pivots on the Frank-Starling law of the heart, and the effects of fluids are measured according to the induced changes on stroke volume. The purpose of this review is to evaluate the boundaries of current macrohemodynamic approach to fluid administration, and to introduce the microcirculatory integration as a fundamental part of tissue perfusion monitoring. Macrocirculatory changes induced by volume expansion are not always coupled to proportional changes in microcirculatory perfusion. Loss of hemodynamic coherence limits the value of guiding fluid therapy according to macrohemodynamics, and highlights the importance of evaluating the ultimate target of volume administration, the microcirculation. Current approach to intravascular volume optimization is made from a macrohemodynamic perspective. However, several situations wherein macrocirculatory and microcirculatory coherence is lost have been described. Future clinical trials should explore the usefulness of integrating the microcirculatory evaluation in fluid optimization.

Quantitative computer tomography analysis of post-operative subdural fluid volume predicts recurrence of chronic subdural haematoma.

PubMed

Xu, Fei-Fan; Chen, Jin-Hong; Leung, Gilberto Ka Kit; Hao, Shu-Yu; Xu, Long; Hou, Zong-Gang; Mao, Xiang; Shi, Guang-Zhi; Li, Jing-Sheng; Liu, Bai-Yun

2014-01-01

Post-operative volume of subdural fluid is considered to correlate with recurrence in chronic subdural haematoma (CSDH). Information on the applications of computer-assisted volumetric analysis in patients with CSDHs is lacking. To investigate the relationship between haematoma recurrence and longitudinal changes in subdural fluid volume using CT volumetric analysis. Fifty-four patients harbouring 64 CSDHs were studied prospectively. The association between recurrence rate and CT findings were investigated. Eleven patients (20.4%) experienced post-operative recurrence. Higher pre-operative (over 120 ml) and/or pre-discharge subdural fluid volumes (over 22 ml) were significantly associated with recurrence; the probability of non-recurrence for values below these thresholds were 92.7% and 95.2%, respectively. CSDHs with larger pre-operative (over 15.1 mm) and/or residual (over 11.7 mm) widths also had significantly increased recurrence rates. Bilateral CSDHs were not found to be more likely to recur in this series. On receiver-operating characteristic curve, the areas under curve for the magnitude of changes in subdural fluid volume were greater than a single time-point measure of either width or volume of the subdural fluid cavity. Close imaging follow-up is important for CSDH patients for recurrence prediction. Using quantitative CT volumetric analysis, strong evidence was provided that changes in the residual fluid volume during the 'self-resolution' period can be used as significantly radiological predictors of recurrence.

Pressure-controlled drainage of cerebrospinal fluid: clinical experience with a new type of ventricular catheter (Ventcontrol MTC)and an integrated Piezo-resistive sensor at its tip: technical note.

PubMed

Piek, J; Raes, P

1996-01-01

We described a new ventricular catheter that is the combination of a "classic" ventricular catheter with a piezo-resistive transducer at its tip. The device allows parallel recordings of intraventricular fluid pressure via a chip and a fluid-filled external transducer, drainage of cerebrospinal fluid from the ventricle or injection of fluid into the ventricle with simultaneous monitoring of intracranial pressure, and recording of brain tissue pressure in cases of misplacement or dislocation of the ventricular catheter or in cases of progressively narrowing ventricles caused by brain edema. Clinical tests in various situations at different pressure ranges (total recording time, 1356 h in 13 patients) gave excellent correlations of both pressures. Application of the device is especially indicated in clinical situations in which pressure-controlled drainage is desirable, occlusion of ventricular bolts is likely, or pressure-volume tests are needed.

Preferential effects of low volume versus high volume replacement with crystalloid fluid in a hemorrhagic shock model in pigs.

PubMed

Ponschab, Martin; Schöchl, Herbert; Keibl, Claudia; Fischer, Henrik; Redl, Heinz; Schlimp, Christoph J

2015-10-06

Fluid resuscitation is a core stone of hemorrhagic shock therapy, and crystalloid fluids seem to be associated with lower mortality compared to colloids. However, as redistribution starts within minutes, it has been suggested to replace blood loss with a minimum of a three-fold amount of crystalloids. The hypothesis was that in comparison to high volume (HV), a lower crystalloid volume (LV) achieves a favorable coagulation profile and exerts sufficient haemodynamics in the acute phase of resuscitation. In 24 anaesthetized pigs, controlled arterial blood loss of 50 % of the estimated blood volume was either (n = 12) replaced with a LV (one-fold) or a HV (three-fold) volume of a balanced, acetated crystalloid solution at room temperature. Hemodynamic parameters, dilution effects and coagulation profile by standard coagulation tests and thromboelastometry at baseline and after resuscitation were determined in both groups. LV resuscitation increased MAP significantly less compared to the HV, 61 ± 7 vs. 82 ± 14 mmHg (p < 0.001) respectively, with no difference between lactate and base excess between groups. Haematocrit after fluid replacement was 0.20 vs. 0.16 (LV vs. HV, p < 0.001), suggesting a grade of blood dilution of 32 vs. 42 % (p < 0.001) compared to baseline values. Compared to LV, HV resulted in decreased core temperature (37.5 ± 0.2 vs. 36.0 ± 0.6 °C, p < 0.001), lower platelet count (318 ± 77 vs. 231 ± 53 K/μL, p < 0.01) and lower plasma fibrinogen levels (205 ± 19 vs. 168 ± 24 mg/dL, p < 0.001). Thromboelastometric measurements showed a significant impairment on viscoelastic clot properties following HV group. While prothrombin time index decreased significantly more in the HV group, activated partial thromboplastin time did not differ between both groups. HV did not result in hyperchloraemic acidosis. Coagulation parameters represented by plasma fibrinogen and ROTEM parameters were also less impaired with LV. With regrad to hematocrit, 60 % of LV remained intracascular , while in HV only 30 % remained in circulation within the first hour of administration. In the acute setting of 50 % controlled blood loss, a one fold LV crystalloid replacement strategy is sufficient to adequately raise blood pressure up to a mean arterial pressure >50 mm Hg. The concept of damage control resuscitation (DCR) with permissive hypotension may be better met by using LV as compared to a three fold HV resuscitation strategy. High volume administration of an acetated balanced crystalloid does not lead to hyperchloraemic acidosis, but may negatively influence clinical parameters, such as higher blood pressure, lower body temperature and impaired coagulation parameters, which could potentially increase bleeding after trauma. Replacement of acute blood loss with just an equal amount of an acetated balanced crystalloid appears to be the preferential treatment strategy in the acute phase after controlled bleeding.

A randomized trial of goal directed vs. standard fluid therapy in cytoreductive surgery with hyperthermic intraperitoneal chemotherapy.

PubMed

Colantonio, Luca; Claroni, Claudia; Fabrizi, Luana; Marcelli, Maria Elena; Sofra, Maria; Giannarelli, Diana; Garofalo, Alfredo; Forastiere, Ester

2015-04-01

The use of adequate fluid therapy during cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) remains controversial. The aim of the study was to assess whether the use of fluid therapy protocol combined with goal-directed therapy (GDT) is associated with a significant change in morbidity, length of hospital stay, and mortality compared to standard fluid therapy. Patients American Society of Anesthesiologists (ASA) II-III undergoing CRS and HIPEC were randomized into two groups. The GDT group (N = 38) received fluid therapy according to a protocol guided by monitored hemodynamic parameters. The control group (N = 42) received standard fluid therapy. We evaluated incidence of major complications, total length of hospital stay, total amount of fluids administered, and mortality rate. The incidence of major abdominal complications was 10.5% in GDT group and 38.1% in the control group (P = 0.005). The median duration of hospitalization was 19 days in GDT group and 29 days in the control group (P < 0.0001). The mortality rate was zero in GDT group vs. 9.5% in the control group (P = 0.12). GDT group received a significantly (P < 0.0001) lower amount of fluid (5812 ± 1244 ml) than the control group (8269 ± 1452 ml), with a significantly (P < 0.0001) lower volume of crystalloids (3884 ± 1003 vs. 68,528 ± 1413 ml). In CRS and HIPEC, the use of a GDT improves outcome in terms of incidence of major abdominal and systemic postoperative complications and length of hospital stay, compared to standard fluid therapy protocol.

Microfluidic viscometers for shear rheology of complex fluids and biofluids

PubMed Central

Wang, William S.; Vanapalli, Siva A.

2016-01-01

The rich diversity of man-made complex fluids and naturally occurring biofluids is opening up new opportunities for investigating their flow behavior and characterizing their rheological properties. Steady shear viscosity is undoubtedly the most widely characterized material property of these fluids. Although widely adopted, macroscale rheometers are limited by sample volumes, access to high shear rates, hydrodynamic instabilities, and interfacial artifacts. Currently, microfluidic devices are capable of handling low sample volumes, providing precision control of flow and channel geometry, enabling a high degree of multiplexing and automation, and integrating flow visualization and optical techniques. These intrinsic advantages of microfluidics have made it especially suitable for the steady shear rheology of complex fluids. In this paper, we review the use of microfluidics for conducting shear viscometry of complex fluids and biofluids with a focus on viscosity curves as a function of shear rate. We discuss the physical principles underlying different microfluidic viscometers, their unique features and limits of operation. This compilation of technological options will potentially serve in promoting the benefits of microfluidic viscometry along with evincing further interest and research in this area. We intend that this review will aid researchers handling and studying complex fluids in selecting and adopting microfluidic viscometers based on their needs. We conclude with challenges and future directions in microfluidic rheometry of complex fluids and biofluids. PMID:27478521

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients.

PubMed

Zhu, F; Kuhlmann, M K; Kaysen, G A; Sarkar, S; Kaitwatcharachai, C; Khilnani, R; Stevens, L; Leonard, E F; Wang, J; Heymsfield, S; Levin, N W

2006-02-01

Discrepancies in body fluid estimates between segmental bioimpedance spectroscopy (SBIS) and gold-standard methods may be due to the use of a uniform value of tissue resistivity to compute extracellular fluid volume (ECV) and intracellular fluid volume (ICV). Discrepancies may also arise from the exclusion of fluid volumes of hands, feet, neck, and head from measurements due to electrode positions. The aim of this study was to define the specific resistivity of various body segments and to use those values for computation of ECV and ICV along with a correction for unmeasured fluid volumes. Twenty-nine maintenance hemodialysis patients (16 men) underwent body composition analysis including whole body MRI, whole body potassium (40K) content, deuterium, and sodium bromide dilution, and segmental and wrist-to-ankle bioimpedance spectroscopy, all performed on the same day before a hemodialysis. Segment-specific resistivity was determined from segmental fat-free mass (FFM; by MRI), hydration status of FFM (by deuterium and sodium bromide), tissue resistance (by SBIS), and segment length. Segmental FFM was higher and extracellular hydration of FFM was lower in men compared with women. Segment-specific resistivity values for arm, trunk, and leg all differed from the uniform resistivity used in traditional SBIS algorithms. Estimates for whole body ECV, ICV, and total body water from SBIS using segmental instead of uniform resistivity values and after adjustment for unmeasured fluid volumes of the body did not differ significantly from gold-standard measures. The uniform tissue resistivity values used in traditional SBIS algorithms result in underestimation of ECV, ICV, and total body water. Use of segmental resistivity values combined with adjustment for body volumes that are neglected by traditional SBIS technique significantly improves estimations of body fluid volume in hemodialysis patients.

A Solar Volumetric Receiver: Influence of Absorbing Cells Configuration on Device Thermal Performance

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Shuja, S. Z.

2017-01-01

Thermal performance of a solar volumetric receiver incorporating the different cell geometric configurations is investigated. Triangular, hexagonal, and rectangular absorbing cells are incorporated in the analysis. The fluid volume fraction, which is the ratio of the volume of the working fluid over the total volume of solar volumetric receiver, is introduced to assess the effect of cell size on the heat transfer rates in the receiver. In this case, reducing the fluid volume fraction corresponds to increasing cell size in the receiver. SiC is considered as the cell material, and air is used as the working fluid in the receiver. The Lambert's Beer law is incorporated to account for the solar absorption in the receiver. A finite element method is used to solve the governing equation of flow and heat transfer. It is found that the fluid volume fraction has significant effect on the flow field in the solar volumetric receiver, which also modifies thermal field in the working fluid. The triangular absorbing cell gives rise to improved effectiveness of the receiver and then follows the hexagonal and rectangular cells. The second law efficiency of the receiver remains high when hexagonal cells are used. This occurs for the fluid volume fraction ratio of 0.5.

Fluid volume displacement at the oval and round windows with air and bone conduction stimulation.

PubMed

Stenfelt, Stefan; Hato, Naohito; Goode, Richard L

2004-02-01

The fluids in the cochlea are normally considered incompressible, and the fluid volume displacement of the oval window (OW) and the round window (RW) should be equal and of opposite phase. However, other channels, such as the cochlear and vestibular aqueducts, may affect the fluid flow. To test if the OW and RW fluid flows are equal and of opposite phase, the volume displacement was assessed by multiple point measurement at the windows with a laser Doppler vibrometer. This was done during air conduction (AC) stimulation in seven fresh human temporal bones, and with bone conduction (BC) stimulation in eight temporal bones and one human cadaver head. With AC stimulation, the average volume displacement of the two windows is within 3 dB, and the phase difference is close to 180 degrees for the frequency range 0.1 to 10 kHz. With BC stimulation, the average volume displacement difference between the two windows is greater: below 2 kHz, the volume displacement at the RW is 5 to 15 dB greater than at the OW and above 2 kHz more fluid is displaced at the OW. With BC stimulation, lesions at the OW caused only minor changes of the fluid flow at the RW.

Fluid volume displacement at the oval and round windows with air and bone conduction stimulation

NASA Astrophysics Data System (ADS)

Stenfelt, Stefan; Hato, Naohito; Goode, Richard L.

2004-02-01

The fluids in the cochlea are normally considered incompressible, and the fluid volume displacement of the oval window (OW) and the round window (RW) should be equal and of opposite phase. However, other channels, such as the cochlear and vestibular aqueducts, may affect the fluid flow. To test if the OW and RW fluid flows are equal and of opposite phase, the volume displacement was assessed by multiple point measurement at the windows with a laser Doppler vibrometer. This was done during air conduction (AC) stimulation in seven fresh human temporal bones, and with bone conduction (BC) stimulation in eight temporal bones and one human cadaver head. With AC stimulation, the average volume displacement of the two windows is within 3 dB, and the phase difference is close to 180° for the frequency range 0.1 to 10 kHz. With BC stimulation, the average volume displacement difference between the two windows is greater: below 2 kHz, the volume displacement at the RW is 5 to 15 dB greater than at the OW and above 2 kHz more fluid is displaced at the OW. With BC stimulation, lesions at the OW caused only minor changes of the fluid flow at the RW.

Apparatus for removing a contaminant from a fluid stream

DOEpatents

Brewster, M.D.; Posa, R.P.

1998-12-22

A device for removing a contaminant from a fluid stream flowing within a conduit is disclosed. The device includes a container and a barrier. The container has a first wall generated about an axis and a second wall generated about the same axis. The first wall defines a first volume therewithin, while the first and second walls define an annular second volume therebetween. Both the first and second volumes are sealed at one end of the device, while at the other end of the device the second volume only is sealed. A filter material occupies the second volume. The first and second walls are permeable to the fluid stream and are capable of retaining the filter material in the second volume. The barrier is impermeable to the fluid stream and creates a seal between the second wall and the conduit wall. The barrier is positioned adjacent the other end of the device such that when the other end of the device is the upstream end, the fluid stream must sequentially pass into the first volume, through the first wall, into the second volume and through the filter material, and through the second wall. 4 figs.

Apparatus for removing a contaminant from a fluid stream

DOEpatents

Brewster, Michael D.; Posa, Richard P.

1998-01-01

A device for removing a contaminant from a fluid stream flowing within a conduit is disclosed. The device includes a container and a barrier. The container has a first wall generated about an axis and a second wall generated about the same axis. The first wall defines a first volume therewithin, while the first and second walls define an annular second volume therebetween. Both the first and second volumes are sealed at one end of the device, while at the other end of the device the second volume only is sealed. A filter material occupies the second volume. The first and second walls are permeable to the fluid stream and are capable of retaining the filter material in the second volume. The barrier is impermeable to the fluid stream and creates a seal between the second wall and the conduit wall. The barrier is positioned adjacent the other end of the device such that when the other end of the device is the upstream end, the fluid stream must sequentially pass into the first volume, through the first wall, into the second volume and through the filter material, and through the second wall.

Apparatus for Pumping a Fluid

NASA Technical Reports Server (NTRS)

van Boeyen, Roger W. (Inventor); Reeh, Jonathan A. (Inventor); Kesmez, Mehmet (Inventor); Heselmeyer, Eric A. (Inventor); Parkey, Jeffrey S. (Inventor)

2016-01-01

An electrochemically actuated pump and an electrochemical actuator for use with a pump. The pump includes one of various stroke volume multiplier configurations with the pressure of a pumping fluid assisting actuation of a driving fluid bellows. The electrochemical actuator has at least one electrode fluidically coupled to the driving fluid chamber of the first pump housing and at least one electrode fluidically coupled to the driving fluid chamber of the second pump housing. Accordingly, the electrochemical actuator selectively pressurizes hydrogen gas within a driving fluid chamber. The actuator may include a membrane electrode assembly including an ion exchange membrane with first and second catalyzed electrodes in contact with opposing sides of the membrane, and first and second hydrogen gas chambers in fluid communication with the first and second electrodes, respectively. A controller may reverse the polarity of a voltage source electrically coupled to the current collectors.

Fluid resuscitation with isotonic or hypertonic saline solution avoids intraneural calcium influx after traumatic brain injury associated with hemorrhagic shock.

PubMed

Balbino, Marcos; Capone Neto, Antonio; Prist, Ricardo; Ferreira, Alice Teixeira; Poli-de-Figueiredo, Luiz F

2010-04-01

Calcium is one of the triggers involved in ischemic neuronal death. Because hypotension is a strong predictor of outcome in traumatic brain injury (TBI), we tested the hypothesis that early fluid resuscitation blunts calcium influx in hemorrhagic shock associated to TBI. Fifteen ketamine-halothane anesthetized mongrel dogs (18.7 kg +/- 1.4 kg) underwent unilateral cryogenic brain injury. Blood was shed in 5 minutes to a target mean arterial pressure of 40 mm Hg to 45 mm Hg and maintained at these levels for 20 minutes (shed blood volume = 26 mL/kg +/- 7 mL/kg). Animals were then randomized into three groups: CT (controls, no fluid resuscitation), HS (7.5% NaCl, 4 mL/kg, in 5 minutes), and LR (lactate Ringer's, 33 mL/kg, in 15 minutes). Twenty minutes later, a craniotomy was performed and cerebral biopsies were obtained next to the lesion ("clinical penumbra") and from the corresponding contralateral side ("lesion's mirror") to determine intracellular calcium by fluorescence signals of Fura-2-loaded cells. Controls remained hypotensive and in a low-flow state, whereas fluid resuscitation improved hemodynamic profile. There was a significant increase in intracellular calcium in the injured hemisphere in CT (1035 nM +/- 782 nM), compared with both HS (457 nM +/- 149 nM, p = 0.028) and LR (392 nM +/- 178 nM, p = 0.017), with no differences between HS and LR (p = 0.38). Intracellular calcium at the contralateral, uninjured hemisphere was 438 nM +/- 192 nM in CT, 510 nM +/- 196 nM in HS, and 311 nM +/- 51 nM in LR, with no significant differences between them. Both small volume hypertonic saline and large volume lactated Ringer's blunts calcium influx in early stages of TBI associated to hemorrhagic shock. No fluid resuscitation strategy promotes calcium influx and further neural damage.

Fluid therapy for children: facts, fashions and questions

PubMed Central

Holliday, Malcolm A; Ray, Patricio E; Friedman, Aaron L

2007-01-01

Fluid therapy restores circulation by expanding extracellular fluid. However, a dispute has arisen regarding the nature of intravenous therapy for acutely ill children following the development of acute hyponatraemia from overuse of hypotonic saline. The foundation on which correct maintenance fluid therapy is built is examined and the difference between maintenance fluid therapy and restoration or replenishment fluid therapy for reduction in extracellular fluid volume is delineated. Changing practices and the basic physiology of extracellular fluid are discussed. Some propose changing the definition of “maintenance therapy” and recommend isotonic saline be used as maintenance and restoration therapy in undefined amounts leading to excess intravenous sodium chloride intake. Intravenous fluid therapy for children with volume depletion should first restore extracellular volume with measured infusions of isotonic saline followed by defined, appropriate maintenance therapy to replace physiological losses according to principles established 50 years ago. PMID:17175577

Energy dissipation in a finite volume of magnetic fluid

NASA Astrophysics Data System (ADS)

Bashtovoi, V.; Motsar, A.; Reks, A.

2017-06-01

This study is devoted to investigation of energy dissipation processes which happen in a magnetic fluid drop with compound magnet during its motion in cylindrical non magnetic container. The possibility of energy dissipation control by means of electromagnetic field is examined. It's found that a change of magnetic field of compound magnet can lead to both increase and decrease of oscillation decay time and relative damping factor can be varied in a range of ±35%.

Optimization of MR fluid Yield stress using Taguchi Method and Response Surface Methodology Techniques

NASA Astrophysics Data System (ADS)

Mangal, S. K.; Sharma, Vivek

2018-02-01

Magneto rheological fluids belong to a class of smart materials whose rheological characteristics such as yield stress, viscosity etc. changes in the presence of applied magnetic field. In this paper, optimization of MR fluid constituents is obtained with on-state yield stress as response parameter. For this, 18 samples of MR fluids are prepared using L-18 Orthogonal Array. These samples are experimentally tested on a developed & fabricated electromagnet setup. It has been found that the yield stress of MR fluid mainly depends on the volume fraction of the iron particles and type of carrier fluid used in it. The optimal combination of the input parameters for the fluid are found to be as Mineral oil with a volume percentage of 67%, iron powder of 300 mesh size with a volume percentage of 32%, oleic acid with a volume percentage of 0.5% and tetra-methyl-ammonium-hydroxide with a volume percentage of 0.7%. This optimal combination of input parameters has given the on-state yield stress as 48.197 kPa numerically. An experimental confirmation test on the optimized MR fluid sample has been then carried out and the response parameter thus obtained has found matching quite well (less than 1% error) with the numerically obtained values.

Fluid responsiveness predicted by transcutaneous partial pressure of oxygen in patients with circulatory failure: a prospective study.

PubMed

Xu, Jingyuan; Peng, Xiao; Pan, Chun; Cai, Shixia; Zhang, Xiwen; Xue, Ming; Yang, Yi; Qiu, Haibo

2017-12-01

Significant effort has been devoted to defining parameters for predicting fluid responsiveness. Our goal was to study the feasibility of predicting fluid responsiveness by transcutaneous partial pressure of oxygen (PtcO 2 ) in the critically ill patients. This was a single-center prospective study conducted in the intensive care unit of a tertiary care teaching hospital. Shock patients who presented with at least one clinical sign of inadequate tissue perfusion, defined as systolic blood pressure <90 mmHg or a decrease >40 mmHg in previously hypertensive patients or the need for vasopressive drugs; urine output <0.5 ml/kg/h for 2 h; tachycardia; lactate >4 mmol/l, for less than 24 h in the absence of a contraindication for fluids were eligible to participate in the study. PtcO 2 was continuously recorded before and during a passive leg raising (PLR) test, and then before and after a 250 ml rapid saline infusion in 10 min. Fluid responsiveness is defined as a change in the stroke volume ≥10% after 250 ml of volume infusion. Thirty-four patients were included, and 14 responded to volume expansion. In the responders, the mean arterial pressure, central venous pressure, cardiac output, stroke volume and PtcO 2 increased significantly, while the heart rate decreased significantly by both PLR and volume expansion. Changes in the stroke volume induced either by PLR or volume expansion were significantly greater in responders than in non-responders. The correlation between the changes in PtcO 2 and stroke volume induced by volume expansion was significant. Volume expansion induced an increase in the PtcO 2 of 14% and PLR induced an increase in PtcO 2 of 13% predicted fluid responsiveness. This study suggested the changes in PtcO 2 induced by volume expansion and a PLR test predicted fluid responsiveness in critically ill patients. Trial registration NCT02083757.

Episodic Tremor and Slip Explained by Fluid-Enhanced Microfracturing and Sealing

NASA Astrophysics Data System (ADS)

Bernaudin, M.; Gueydan, F.

2018-04-01

Episodic tremor and slow-slip events at the deep extension of plate boundary faults illuminate seismic to aseismic processes around the brittle-ductile transition. These events occur in volumes characterized by overpressurized fluids and by near failure shear stress conditions. We present a new modeling approach based on a ductile grain size-sensitive rheology with microfracturing and sealing, which provides a mechanical and field-based explanation of such phenomena. We also model pore fluid pressure variation as a function of changes in porosity/permeability and strain rate-dependent fluid pumping. The fluid-enhanced dynamic evolution of microstructures defines cycles of ductile strain localization and implies increase in pore fluid pressure. We propose that slow-slip events are ductile processes related to transient strain localization, while nonvolcanic tremor corresponds to fracturing of the whole rock at the peak of pore fluid pressure. Our model shows that the availability of fluids and the efficiency of fluid pumping control the occurrence and the P-T conditions of episodic tremor and slip.

Blood pool scintigraphy of the skull in relation to head-down tilt provocation in patients with chronic tension-type headache and controls.

PubMed

Hannerz, Jan; Schnell, P-O; Larsson, Stig; Jacobsson, Hans

2004-03-01

To investigate the mechanisms behind the increase of chronic tension-type headache during head-down tilt. The pathophysiology of chronic tension-type headache is unknown. Ten patients suffering from chronic tension-type headache and 10 age- and sex-matched controls were studied with respect to pain intensity and alterations in cranial blood volume using planar scintigraphy and radiolabeled autologous erythrocytes before, during, and after head-down tilt, a procedure known to increase chronic tension-type headache. Four of 8 patients with chronic tension-type headache studied had increased cerebrospinal fluid pressure. During head-down tilt, the pain increased significantly in the group with chronic tension-type headache (P <.001) while the procedure did not cause headache in the controls. Blood volume significantly increased extracranially and decreased intracranially in both groups during head-down tilt. The extracranial nasal blood volume was significantly related to the pain experienced by the patients with chronic tension-type headache before and during head-down tilt. Although the changes in blood volume and, presumably, the increase of intracranial pressure were similar in the patients with chronic tension-type headache and the controls, only the patients experienced pain and pain increase during head-down tilt. This indicates that the pre-head-down tilt conditions must be different in the 2 groups and should be related to increased cerebrospinal fluid pressure/intracranial venous pressure in patients with chronic tension-type headache compared with controls. A difference in central mechanisms may, however, also be of importance for the difference in headache provocation in the 2 groups during head-down tilt.

Systems and methods for separating a multiphase fluid

NASA Technical Reports Server (NTRS)

Weislogel, Mark M. (Inventor); Thomas, Evan A. (Inventor); Graf, John C. (Inventor)

2011-01-01

Apparatus and methods for separating a fluid are provided. The apparatus can include a separator and a collector having an internal volume defined at least in part by one or more surfaces narrowing toward a bottom portion of the volume. The separator can include an exit port oriented toward the bottom portion of the volume. The internal volume can receive a fluid expelled from the separator into a flow path in the collector and the flow path can include at least two directional transitions within the collector.

Heat recovery system employing a temperature controlled variable speed fan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, W.T.

1986-05-20

A heat recovery system is described for use in recovering heat from an industrial process producing a heated fluid comprising: a source of inlet air; a housing coupled to the source and including a heat exchanger; means for passing the heated fluid through the heat exchanger; the housing including means for moving a variable volume of air adjustable over a continuous range from the source through the heat exchanger; air discharge means communicating with the housing for discharging air which has passed through the heat exchanger; a control system including first temperature sensing means for sensing the discharge temperature ofmore » the discharge air moving through the discharge means and a control circuit coupled to the first temperature sensing means and to the moving means for varying the volume of air moved in response to the sensed discharge temperature to control the temperature of discharge air passing through the discharge means at a first predetermined value; and the control system including second temperature sensing means for sensing the temperature of the source of inlet air and valve means coupled to and controlled by the control circuit to cause liquid to bypass the heat exchanger when the inlet air temperature rises above a second predetermined value.« less

A new approach for determining the volume of cerebral extracellular fluid and demonstration of its communication with c.s.f

PubMed Central

Friede, Reinhard L.; Hu, Kuo Hao

1971-01-01

1. A new technique is presented for determining the volume of extracellular space in bowfin (Amia calva) brain during in vitro incubation. It consists of solving simultaneous equations which are applied to determine the volume of extracellular space as well as intracellular marker concentration. This technique allows for a better insight into the redistribution of marker between incubation medium and extracellular space as well as between extracellular and intracellular space. 2. Na+, K+ and Cl- equilibrated within 10-15 min between incubation medium and extracellular space. There was no evidence of a homoeostatic mechanism controlling the concentration of these ions in the extracellular fluid, which appeared to be in equilibrium with cerebrospinal fluid. The extracellular spaces of these ions were identical: Na+, 23·4; K+, 23·3 and Cl-, 23·2%. 3. Sorbitol equilibrated with the extracellular fluid within 45 min and indicated an extracellular space of 22·6%, nearly identical with that for electrolytes. 4. Vastly different `spaces' were obtained for [3H]methoxy inulin, which equilibrated within 45 min with a 13% space and [14C]carboxyl inulin, which showed a 46% space value for only 30 min. The difference may be explained by marker decomposition. The 9% difference between the [3H]methoxy inulin and sorbitol spaces may be explained by a `packing' factor attributable to molecular size. PMID:5124573

40 CFR Appendix 7 to Subpart A of... - Determination of the Amount of Non-Aqueous Drilling Fluid (NAF) Base Fluid From Drill Cuttings by...

Code of Federal Regulations, 2013 CFR

2013-07-01

... multiplying the density of the small volume NAF-cuttings discharges (ρsvd) times the volume of the small...-cuttings discharges (kg) ρsvd = density of the small volume NAF-cuttings discharges (kg/bbl) VSVD = volume of the small volume NAF-cuttings discharges (bbl) The density of the small volume NAF-cuttings...

40 CFR Appendix 7 to Subpart A of... - Determination of the Amount of Non-Aqueous Drilling Fluid (NAF) Base Fluid From Drill Cuttings by...

Code of Federal Regulations, 2014 CFR

2014-07-01

... multiplying the density of the small volume NAF-cuttings discharges (ρsvd) times the volume of the small...-cuttings discharges (kg) ρsvd = density of the small volume NAF-cuttings discharges (kg/bbl) VSVD = volume of the small volume NAF-cuttings discharges (bbl) The density of the small volume NAF-cuttings...

40 CFR Appendix 7 to Subpart A of... - Determination of the Amount of Non-Aqueous Drilling Fluid (NAF) Base Fluid From Drill Cuttings by...

Code of Federal Regulations, 2012 CFR

2012-07-01

... multiplying the density of the small volume NAF-cuttings discharges (ρsvd) times the volume of the small...-cuttings discharges (kg) ρsvd = density of the small volume NAF-cuttings discharges (kg/bbl) VSVD = volume of the small volume NAF-cuttings discharges (bbl) The density of the small volume NAF-cuttings...

Passenger fluid volumes measured before and after a prolonged commercial jet flight.

NASA Technical Reports Server (NTRS)

Johnson, P. C.; Carpentier, W. R.; Driscoll, T. B.; Lapinta, C. K.; Rummel, J. A.; Sawin, C. F.

1972-01-01

Interstitial and intracellular fluid volumes were calculated from measured plasma volume, extracellular volume and total body water of six subjects before and after a 24-hour commercial overseas flight. No change occurred in these spaces or in peripheral hematocrit or total serum protein concentration. The subjective feeling of dehydration and the actual swelling of the lower extremities characteristically found among passengers at the end of a long trip of this type seems to represent a shift in body fluids to the dependent portions of the body rather than water retention or a decrease in the intravascular water volume.

Rapid Weight Loss and the Body Fluid Balance and Hemoglobin Mass of Elite Amateur Boxers

PubMed Central

Reljic, Dejan; Hässler, Eike; Jost, Joachim; Friedmann-Bette, Birgit

2013-01-01

Context Dehydration is assumed to be a major adverse effect associated with rapid loss of body mass for competing in a lower weight class in combat sports. However, the effects of such weight cutting on body fluid balance in a real-life setting are unknown. Objective To examine the effects of 5% or greater loss of body mass within a few days before competition on body water, blood volume, and plasma volume in elite amateur boxers. Design Case-control study. Setting Sports medicine laboratory. Patients or Other Participants Seventeen male boxers (age = 19.2 ± 2.9 years, height = 175.1 ± 7.0 cm, mass = 65.6 ± 9.2 kg) were assigned to the weight-loss group (WLG; n = 10) or the control group (CON; n = 7). Intervention(s) The WLG reduced body mass by restricting fluid and food and inducing excessive sweat loss by adhering to individual methods. The CON participated in their usual precompetition training. Main Outcome Measure(s) During an ordinary training period (t-1), 2 days before competition (t-2), and 1 week after competition (t-3), we performed bioelectrical impedance measurements; calculated total body water, intracellular water, and extracellular water; and estimated total hemoglobin mass (tHbmass), blood volume, and plasma volume by the CO-rebreathing method. Results In the WLG, the loss of body mass (5.6% ± 1.7%) led to decreases in total body water (6.0% ± 0.9%), extracellular water (12.4% ± 7.6%), tHbmass (5.3% ± 3.8%), blood volume (7.6% ± 2.1%; P < .001), and plasma volume (8.6% ± 3.9%). The intracellular water did not change (P > .05). At t-3, total body water, extracellular water, and plasma volume had returned to near baseline values, but tHbmass and blood volume still were less than baseline values (P < .05). In CON, we found no changes (P > .05). Conclusions In a real-life setting, the loss of approximately 6% body mass within 5 days induced hypohydration, which became evident by the decreases in body water and plasma volume. The reduction in tHbmass was a surprising observation that needs further investigation. PMID:23672332

Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms

PubMed Central

Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

2017-01-01

Objective This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). Method A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Result Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01–1.11; P = 0.016). Conclusion The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms. PMID:29284057

Structural Brain Abnormalities in Successfully Treated HIV Infection: Associations With Disease and Cerebrospinal Fluid Biomarkers.

PubMed

van Zoest, Rosan A; Underwood, Jonathan; De Francesco, Davide; Sabin, Caroline A; Cole, James H; Wit, Ferdinand W; Caan, Matthan W A; Kootstra, Neeltje A; Fuchs, Dietmar; Zetterberg, Henrik; Majoie, Charles B L M; Portegies, Peter; Winston, Alan; Sharp, David J; Gisslén, Magnus; Reiss, Peter

2017-12-27

Brain structural abnormalities have been reported in persons living with human immunodeficiency virus (HIV; PLWH) who are receiving suppressive combination antiretroviral therapy (cART), but their pathophysiology remains unclear. We investigated factors associated with brain tissue volumes and white matter microstructure (fractional anisotropy) in 134 PLWH receiving suppressive cART and 79 comparable HIV-negative controls, aged ≥45 years, from the Comorbidity in Relation to AIDS cohort, using multimodal neuroimaging and cerebrospinal fluid biomarkers. Compared with controls, PLWH had lower gray matter volumes (-13.7 mL; 95% confidence interval, -25.1 to -2.2) and fractional anisotropy (-0.0073; 95% confidence interval, -.012 to -.0024), with the largest differences observed in those with prior clinical AIDS. Hypertension and the soluble CD14 concentration in cerebrospinal fluid were associated with lower fractional anisotropy. These associations were independent of HIV serostatus (Pinteraction = .32 and Pinteraction = .59, respectively) and did not explain the greater abnormalities in brain structure in relation to HIV infection. The presence of lower gray matter volumes and more white matter microstructural abnormalities in well-treated PLWH partly reflect a combination of historical effects of AIDS, as well as the more general influence of systemic factors, such as hypertension and ongoing neuroinflammation. Additional mechanisms explaining the accentuation of brain structure abnormalities in treated HIV infection remain to be identified. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

The Protective Role of Dexpanthenol on the Endometrial Implants in an Experimentally Induced Rat Endometriosis Model.

PubMed

Soylu Karapinar, Oya; Pinar, Neslihan; Özgür, Tümay; Özcan, Oğuzhan; Bayraktar, H Suphi; Kurt, Raziye Keskin; Nural, Orhan

2017-02-01

Dexpanthenol (Dxp), antioxidant and anti-inflammatory agent, plays an important role in the repair systems against oxidative stress and inflammatory response. The objective of this study is to determine the effect of Dxp on experimental endometriosis model. A prospective experimental study was conducted in Experimental Animal Laboratory of Mustafa Kemal University, Hatay. Twenty nonpregnant female Wistar albino rats, in which experimental model of endometriosis was surgically induced, were randomly divided into 2 groups. Group 1 was administered 500 mg/kg/d Dxp intraperitoneally for 14 days, and group 2 was given the same amount of saline solution. After 2 weeks of medication, the rats were killed and implant volumes, histopathologic scores; and levels of serum total antioxidant status, total oxidant status (TOS), and oxidative stress index (OSI) were evaluated. Plasma and peritoneal fluid levels of tumor necrosis factor α (TNF-α) were analyzed. The endometriotic implant volumes, histopathologic scores, and serum TOS and OSI values were significantly decreased ( P < .05) in the Dxp group compared to the control group. Plasma and peritoneal fluid TNF-α levels were significantly decreased ( P < .05) in the Dxp group compared to the control group. Dexpanthenol has free radical scavenger effects, and antioxidant properties has significantly regressed endometriotic implant volumes, histopathologic scores, and serum TOS and OSI values. Serum and peritoneal fluid TNF-α levels were significantly decreased in the Dxp group. So Dxp decreased oxidative stress.

Thoracic Impedance as a Potential Indicator of Gz-induced Presyncope

NASA Technical Reports Server (NTRS)

Howarth, M. S.; Moore, F. B.; Hinghofer-Szalkay, H.; Jezova, D.; Diedrich, A.; Ferris, M. B.; Patwardhan, A. R.; Knapp, C. F.; Evans, J. M.

2008-01-01

We investigated fluid shifts and regulatory responses to variations of posture, exercise, Gz level and radius of rotation in subjects riding NASA Ames 20G centrifuge. Results are from 4 protocols that address radius and exercise effects only. Protocol A: After 10 min supine control, 12 healthy men (35 9 yr, 82.8 7.9 kg) were exposed to rotational 1 Gz (2.5 m radius) for 2 min followed by 20 min alternating between 1 and 1.25 Gz. Blood samples were taken pre and post spin. Protocol B: Same as A, but lower limb exercise (70% V02max) preceded ramps to 1.25 Gz. Protocol C: Same as A but radius of rotation 8.3 m. Protocol D: Same as B but at 8.3 m. The 8 subjects who completed all protocols, increased heart rate (HR) from control by: A: 5, B: 39, C: 11, D: 44 bpm; and the 4 who did not: A: 6, B: 35, C: 20, D: 50 bpm. For thoracic fluid volume, (bioimpedance), the 8 subjects changed from control: A: -394, B: -548, C: -537, D: -708 mL; and the 4: A: -516, B: -652, C: -583, D: -1263 mL. The 4 subjects lost more thoracic fluid volume than the 8, especially in protocol D. A slightly greater increase in HR for the 4 compared to the 8 was not adequate to maintain cardiac output during D. Our data support the concept that thoracic impedance can detect inability to return adequate fluid to the heart, thereby predicting presyncope.

Taylor bubbles at high viscosity ratios: experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Hewakandamby, Buddhika; Hasan, Abbas; Azzopardi, Barry; Xie, Zhihua; Pain, Chris; Matar, Omar

2015-11-01

The Taylor bubble is a single long bubble which nearly fills the entire cross section of a liquid-filled circular tube, often occurring in gas-liquid slug flows in many industrial applications, particularly oil and gas production. The objective of this study is to investigate the fluid dynamics of three-dimensional Taylor bubble rising in highly viscous silicone oil in a vertical pipe. An adaptive unstructured mesh modelling framework is adopted here which can modify and adapt anisotropic unstructured meshes to better represent the underlying physics of bubble rising and reduce computational effort without sacrificing accuracy. The numerical framework consists of a mixed control volume and finite element formulation, a `volume of fluid'-type method for the interface-capturing based on a compressive control volume advection method, and a force-balanced algorithm for the surface tension implementation. Experimental results for the Taylor bubble shape and rise velocity are presented, together with numerical results for the dynamics of the bubbles. A comparison of the simulation predictions with experimental data available in the literature is also presented to demonstrate the capabilities of our numerical method. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

Numerical Cerebrospinal System Modeling in Fluid-Structure Interaction.

PubMed

Garnotel, Simon; Salmon, Stéphanie; Balédent, Olivier

2018-01-01

Cerebrospinal fluid (CSF) stroke volume in the aqueduct is widely used to evaluate CSF dynamics disorders. In a healthy population, aqueduct stroke volume represents around 10% of the spinal stroke volume while intracranial subarachnoid space stroke volume represents 90%. The amplitude of the CSF oscillations through the different compartments of the cerebrospinal system is a function of the geometry and the compliances of each compartment, but we suspect that it could also be impacted be the cardiac cycle frequency. To study this CSF distribution, we have developed a numerical model of the cerebrospinal system taking into account cerebral ventricles, intracranial subarachnoid spaces, spinal canal and brain tissue in fluid-structure interactions. A numerical fluid-structure interaction model is implemented using a finite-element method library to model the cerebrospinal system and its interaction with the brain based on fluid mechanics equations and linear elasticity equations coupled in a monolithic formulation. The model geometry, simplified in a first approach, is designed in accordance with realistic volume ratios of the different compartments: a thin tube is used to mimic the high flow resistance of the aqueduct. CSF velocity and pressure and brain displacements are obtained as simulation results, and CSF flow and stroke volume are calculated from these results. Simulation results show a significant variability of aqueduct stroke volume and intracranial subarachnoid space stroke volume in the physiological range of cardiac frequencies. Fluid-structure interactions are numerous in the cerebrospinal system and difficult to understand in the rigid skull. The presented model highlights significant variations of stroke volumes under cardiac frequency variations only.

Effects of immersion water temperature on whole-body fluid distribution in humans.

PubMed

Stocks, J M; Patterson, M J; Hyde, D E; Jenkins, A B; Mittleman, K D; Taylor, N A S

2004-09-01

In this study, we quantified acute changes in the intracellular and extracellular fluid compartments during upright neutral- and cold-water immersion. We hypothesized that, during short-term cold immersion, fluid shifts would be wholly restricted to the extracellular space. Seven males were immersed 30 days apart: control (33.3 degrees SD 0.6 degrees C); and cold (18.1 degrees SD 0.3 degrees C). Posture was controlled for 4 h prior to a 60-min seated immersion. Significant reductions in terminal oesophageal (36.9 degrees +/- 0.1 degrees -36.3 degrees +/- 0.1 degrees C) and mean skin temperatures (30.3 degrees +/- 0.3 degrees -23.0 degrees +/- 0.3 degrees C) were observed during the cold, but not the control immersion. Both immersions elicited a reduction in intracellular fluid [20.17 +/- 6.02 mL kg(-1) (control) vs. 22.72 +/- 9.90 mL kg(-1)], while total body water (TBW) remained stable. However, significant plasma volume (PV) divergence was apparent between the trials at 60 min [12.5 +/- 1.0% (control) vs. 6.1 +/- 3.1%; P < 0.05], along with a significant haemodilution in the control state (P < 0.05). Plasma atrial natriuretic peptide concentration increased from 18.0 +/- 1.6 to 58.7 +/- 15.1 ng L(-1) (P < 0.05) during cold immersion, consistent with its role in PV regulation. We observed that, regardless of the direction of the PV change, both upright immersions elicited reductions in intracellular fluid. These observations have two implications. First, one cannot assume that PV changes reflect those of the entire extracellular compartment. Second, since immersion also increases interstitial fluid pressure, fluid leaving the interstitium must have been rapidly replaced by intracellular water.

Neural mechanisms of volume regulation.

PubMed

DiBona, G F

1983-05-01

Under steady-state conditions, urinary sodium excretion matches dietary sodium intake. Because extracellular fluid osmolality is tightly regulated, the quantity of sodium in the extracellular fluid determines the volume of this compartment. The left atrial volume receptor mechanism is an example of a neural mechanism of volume regulation. The left atrial mechanoreceptor, which functions as a sensor in the low-pressure vascular system, has a well-defined compliance relating intravascular volume to filling pressure and responds to changes in wall tension by discharging into afferent vagal fibers. These fibers have appropriate central nervous system representation whose related efferent neurohumoral mechanisms regulate thirst, renal excretion of water and sodium, and the redistribution of the extracellular fluid volume.

Characterization of fluid flow by digital correlation of scattered light

NASA Technical Reports Server (NTRS)

Gilbert, John A.; Matthys, Donald R.

1989-01-01

The objective is to produce a physical system suitable for a space environment that can measure fluid velocities in a three-dimensional volume by the development of a particle correlation velocimetry technique. Experimental studies were conducted on a field test cell to demonstrate the suitability and accuracy of digital correlation techniques for measuring two-dimensional fluid flows. This objective was satisfied by: (1) the design of an appropriate illumination and detection system for making velocity measurements within a test cell; (2) the design and construction of a test cell; (3) the preliminary evaluations on fluid and seeding requirements; and (4) the performance of controlled tests using a multiple exposure correlation technique. This presentation is represented by viewgraphs with very little text.

Fluid-fluid interfacial mobility from random walks

NASA Astrophysics Data System (ADS)

Barclay, Paul L.; Lukes, Jennifer R.

2017-12-01

Dual control volume grand canonical molecular dynamics is used to perform the first calculation of fluid-fluid interfacial mobilities. The mobility is calculated from one-dimensional random walks of the interface by relating the diffusion coefficient to the interfacial mobility. Three different calculation methods are employed: one using the interfacial position variance as a function of time, one using the mean-squared interfacial displacement, and one using the time-autocorrelation of the interfacial velocity. The mobility is calculated for two liquid-liquid interfaces and one liquid-vapor interface to examine the robustness of the methods. Excellent agreement between the three calculation methods is shown for all the three interfaces, indicating that any of them could be used to calculate the interfacial mobility.

Physiology of Fluid and Electrolyte Responses During Inactivity: Water Immersion and Bed Rest

NASA Technical Reports Server (NTRS)

Greenleaf, John E.

1984-01-01

This manuscript emphasizes the physiology of fluid-electrolyte-hormonal responses during the prolonged inactivity of bed rest and water immersion. An understanding of the total mechanism of adaptation (deconditioning) should provide more insight into the conditioning process. Findings that need to be confirmed during bed rest and immersion are: (1) the volume and tissues of origin of fluid shifted to the thorax and head; (2) interstitial fluid pressure changes in muscle and subcutaneous tissue, particularly during immersion; and (3) the composition of the incoming presumably interstitial fluid that contributes to the early hypervolemia. Better resolution of the time course and source of the diuretic fluid is needed. Important data will be forthcoming when hypotheses are tested involving the probable action of the emerging diuretic and natriuretic hormones, between themselves and among vasopressin and aldosterone, on diuresis and blood pressure control.

THERMAL EVALUATION OF CONTAMINATED LIQUID ONTO CELL FLOORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

NOEMAIL), J

2009-05-04

For the Salt Disposition Integration Project (SDIP), postulated events in the new Salt Waste Processing Facility (SWPF) can result in spilling liquids that contain Cs-137 and organics onto cell floors. The parameters of concern are the maximum temperature of the fluid following a spill and the time required for the maximum fluid temperature to be reached. Control volume models of the various process cells have been developed using standard conduction and natural convection relationships. The calculations are performed using the Mathcad modeling software. The results are being used in Consolidated Hazards Analysis Planning (CHAP) to determine the controls that maymore » be needed to mitigate the potential impact of liquids containing Cs-137 and flammable organics that spill onto cell floors. Model development techniques and the ease of making model changes within the Mathcad environment are discussed. The results indicate that certain fluid spills result in overheating of the fluid, but the times to reach steady-state are several hundred hours. The long times allow time for spill clean up without the use of expensive mitigation controls.« less

Orbital Spacecraft Consumables Resupply System (OSCRS). Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1987-01-01

The objective was to establish an earth storable fluid tanker concept which satisfies the initial resupply requirements for the Gamma Ray Observatory (GRO) at a reasonable front end cost while providing growth potential for foreseeable future earth storable fluid resupply mission requirements. The estimated costs required to design, develop, qualify, fabricate, and deliver a flight tanker and its associated control avionics, ground support equipment (GSE), and processing facilities, and the contractors costs to support the first operations mission are reviewed.

Space shuttle inflight and postflight fluid shifts measured by leg volume changes.

PubMed

Moore, T P; Thornton, W E

1987-09-01

This is a study of the inflight and postflight leg volume changes associated with spaceflight on Space Shuttle missions. The results of this study show an inflight volume loss of 2 L from lower extremities, 1 L from each leg, representing an 11.6% volume change. The vast majority of this change appears to be a shift in body fluids, both intravascular and extravascular. The fluid shift occurs rapidly on Mission Day 1 (MD-1), with it being essentially complete by 6 to 10 h. The regional origin of shift and leg volume change shows a far greater absolute volume (708 ml vs. 318 ml) and percentage (69% vs. 31%) of the total change coming from the thigh as compared to the lower leg. Postflight, the return of fluid to the lower extremities occurs rapidly with the majority of volume return complete within 1.5 h postlanding. At 1 week postflight there is a residual leg volume decrement of 283 ml or 3.2% that is probably due to tissue loss secondary to atrophic deconditioning and weight loss.

Space Shuttle inflight and postflight fluid shifts measured by leg volume changes

NASA Technical Reports Server (NTRS)

Moore, Thomas P.; Thornton, William E.

1987-01-01

This is a study of the inflight and postflight leg volume changes associated with spaceflight on Space Shuttle missions. The results show an inflight volume loss of 2 l from the lower extremities, 1 l from each leg, representing an 11.6 percent volume change. The vast majority of this change appears to be a shift in body fluids, both intravascular and extravascular. The fluid shift occurs mostly on Mission Day One and is essentially complete by 6 to 10 hr. The regional origin of shift and leg volume changes shows a far greater absolute volume (708 ml vs. 318 ml) and percentage (69 percent vs. 31 percent) of the total change coming from the higher as compared to the lower leg. Postflight, the return of fluid to the lower extremities occurs rapidly with the majority of volume return complete within 1.5 hr postlanding. At 1 week postflight, there is a residual leg volume decrement of 283 ml or 3.2 percent that is probably due to tissue loss secondary to atrophic deconditioning and weight loss.

A combination of biocompatible peritoneal dialysis solutions and residual renal function, peritoneal transport, and inflammation markers: a randomized clinical trial.

PubMed

Lui, Sing Leung; Yung, Susan; Yim, Andrew; Wong, Kui Man; Tong, Kwok Lung; Wong, Kin Shing; Li, Chun Sang; Au, Tak Cheung; Lo, Wai Kei; Ho, Yiu Wing; Ng, Flora; Tang, Colin; Chan, Tak Mao

2012-12-01

The benefits of biocompatible peritoneal dialysis (PD) fluids, particularly for residual renal function (RRF), are controversial. Moreover, the clinical effects of a PD regimen consisting of different biocompatible PD fluids have not been fully established. Prospective, randomized, controlled, open-label study. Patients with end-stage kidney disease newly started on continuous ambulatory PD therapy (N = 150). A 12-month intervention with 3 biocompatible PD fluids (a neutral-pH, low glucose degradation product, 1.5% glucose solution; a solution with 1.1% amino acid; and a fluid with 7.5% icodextrin) or conventional PD fluid. The primary outcome was change in RRF and daily urine volume. Secondary outcomes were peritoneal transport and inflammation markers. RRF, daily urine volume, serum and dialysate cytokine levels. RRF(3.24 ± 1.98 vs 2.88 ± 2.43 mL/min/1.73 m(2); P = 0.9) and rate of decline in RRF (-0.76 ± 1.77 vs -0.91 ± 1.92 mL/min/1.73 m(2) per year; P = 0.6) did not differ between the biocompatible- and conventional-PD-fluid groups. However, patients using the biocompatible PD fluids had better preservation of daily urine volume (959 ± 515 vs 798 ± 615 mL/d in the conventional group, P = 0.02 by comparison of difference in overall change by repeated-measures analysis of variance). Their dialysate-plasma creatinine ratio at 4 hours was higher at 12 months (0.78 ± 0.13 vs 0.68 ± 0.12; P = 0.01 for comparison of the difference in overall change by repeated-measures analysis of variance). They also had significantly higher serum levels of adiponectin and overnight spent dialysate levels of cancer antigen 125, adiponectin, and interleukin 6 (IL-6). No differences between the 2 groups were observed for serum C-reactive protein and IL-6 levels. Unblinded, relatively short follow-up; no formal sample-size calculations. Use of a combination of 3 biocompatible PD fluids for 12 months compared with conventional PD fluid did not affect RRF, but was associated with better preservation of daily urine volume. The biocompatible PD fluids also lead to changes in small-solute transport and an increase in dialysate cancer antigen 125, IL-6, adiponectin, and systemic adiponectin levels, but have no effect on systemic inflammatory response. The clinical significance of these changes, while of great interest, remains to be determined by further studies. Copyright © 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Targets of perioperative fluid therapy and their effects on postoperative outcome: a systematic review and meta-analysis.

PubMed

Berger, M M; Gradwohl-Matis, I; Brunauer, A; Ulmer, H; Dünser, M W

2015-07-01

Perioperative fluid management plays a fundamental role in maintaining organ perfusion, and is considered to affect morbidity and mortality. Targets according to which fluid therapy should be administered are poorly defined. This systematic review aimed to identify specific targets for perioperative fluid therapy. The PubMed database (January 1993-December 2013) and reference lists were searched to identify clinical trials which evaluated specific targets of perioperative fluid therapy and reported clinically relevant perioperative endpoints in adult patients. Only studies in which targeted fluid therapy was the sole intervention were included into the main data analysis. A pooled data analysis was used to compare mortality between goal-directed fluid therapy and control interventions. Thirty-six clinical studies were selected. Sixteen studies including 1224 patients specifically evaluated targeted fluid therapy and were included into the main data analysis. Three specific targets for perioperative fluid therapy were identified: a systolic or pulse pressure variation <10-12%, an increase in stroke volume <10%, and a corrected flow time of 0.35-0.4 s in combination with an increase in stroke volume <10%. Targeting any one of these goals resulted in less postoperative complications (pooled data analysis: OR 0.53; CI95, 0.34-0.83; P=0.005) and a shorter length of intensive care unit/hospital stay, but no difference in postoperative mortality (pooled data analysis: OR 0.61; CI95, 0.33-1.11; P=0.12). This systematic review identified three goals for perioperative fluid administration, targeting of which appeared to be associated with less postoperative complications and shorter intensive care unit/hospital lengths of stay. Perioperative mortality remained unaffected.

Dynamics of pleural fluid effusion and chylothorax in the fetus and newborn: role of the lymphatic system.

PubMed

Bellini, C; Ergaz, Z; Boccardo, F; Bellini, T; Campisi, C C; Bonioli, E; Ramenghi, L A

2013-06-01

Pleural fluid effusion particularly chylothorax is a relatively rare occurrence in the newborn, but when it occurs it is often life-threatening. In this article, we describe and illustrate the morphologic features of the visceral and parietal pleura including pleural lymphatics and the physiology and pathophysiology of pleural fluid balance. The role and function of the lymphatic system in controlling the volume and composition of pleural liquid are detailed and a conceptual scheme presented. Finally, the crucial role of inadequate lymphatic drainage (either functional overload from an imbalance in Starling forces or mechanical insufficiency from lymphatic dysplasia) is emphasized.

Stress, Aging and Thirst

NASA Technical Reports Server (NTRS)

Greenleaf, John E.

1998-01-01

After growth during adolesence, total body water decreases progressively with aging from 65% of body weight to about 53% of body weight in the 70th decade; a majority of the loss occurs from the extracellular volume, from 42% to about 25%, respectively. Cellular volume also reaches equilibrium in the 70th decade at about 25% of body weight. Various stresses such as exercise, heat and attitude exposure, ad prior dehydration attenuate voluntary fluid intake (involuntary dehydration). Voluntary fluid intake appears to decrease with aging (involuntary dehydration in this sense aging can be considered as a stress. Kidney function and muscle mass (80% water) decrease somewhat with aging, and voluntary fluid intake (thirst) is also attenuated. Thirst is stimulated by increasing osmolality (hypernatremia) of the extracellular fluid and by decreased extracellular volume (mainly plasma volume) which act to increase intracellular fluid volume osmolality to activiate drinking. The latter decreases fluid compartment osmolality which ' It terminates drinking. However, this drinking mechanism seems to be attenuated with aging such that increasing plasma osmolality no longer stimulates fluid intake appropriately. Hypernatremia in the elderly has been associated all too frequently with greater incidence of bacterial infection and increased mortality. Involuntary dehydration can be overcome in young men by acclimation to an intermittent exercise-in-heat training program. Perhaps exercise training in the elderly would also increase voluntary fluid intake and increase muscle mass to enhance retention of water.

Clinical usefulness of the definitions for defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output in decompensated heart failure: a descriptive exploratory study.

PubMed

de Souza, Vanessa; Zeitoun, Sandra Salloum; Lopes, Camila Takao; de Oliveira, Ana Paula Dias; Lopes, Juliana de Lima; de Barros, Alba Lucia Bottura Leite

2015-09-01

To assess the clinical usefulness of the operational definitions for the defining characteristics of the NANDA International nursing diagnoses, activity intolerance, decreased cardiac output and excess fluid volume, and the concomitant presence of those diagnoses in patients with decompensated heart failure. Content validity of the operational definitions for the defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output have been previously validated by experts. Their clinical usefulness requires clinical validation. This was a descriptive exploratory study. Two expert nurses independently assessed 25 patients with decompensated heart failure for the presence or absence of 29 defining characteristics. Interrater reliability was analysed using the Kappa coefficient as a measure of clinical usefulness. The Fisher's exact test was used to test the association of the defining characteristics of activity intolerance and excess fluid volume in the presence of decreased cardiac output, and the correlation between the three diagnoses. Assessments regarding the presence of all defining characteristics reached 100% agreement, except with anxiety. Five defining characteristics of excess fluid volume were significantly associated with the presence of decreased cardiac output. Concomitant presence of the three diagnoses occurred in 80% of the patients. However, there was no significant correlation between the three diagnoses. The operational definitions for the diagnoses had strong interrater reliability, therefore they were considered clinically useful. Only five defining characteristics were representative of the association between excess fluid volume and decreased cardiac output. Therefore, excess fluid volume is related to decreased cardiac output, although these diagnoses are not necessarily associated with activity intolerance. The operational definitions may favour early recognition of the sequence of responses to decompensation, guiding the choice of common interventions to improve or resolve excess fluid volume and decreased cardiac output. © 2015 John Wiley & Sons Ltd.

Buckling of Dielectric Elastomeric Plates for Electrically Active Microfludic Pumps

NASA Astrophysics Data System (ADS)

Holmes, Douglas; Tavakol, Behrouz; Bozlar, Michael; Froehlicher, Guillaume; Stone, Howard; Aksay, Ilhan

2013-11-01

Fluid flow can be directed and controlled by a variety of mechanisms within industrial and biological environments. Advances in microfluidic technology have required innovative ways to control fluid flow on a small scale, and the ability to actively control fluid flow within microfluidic devices is crucial for advancements in nanofluidics, biomedical fluidic devices, and digital microfluidics. In this work, we present a means for microfluidic control via the electrical actuation of thin, flexible valves within microfluidic channels. These structures consist of a dielectric elastomer confined between two compliant electrodes that can be actively and reversibly buckle out of plane to pump fluids from an applied voltage. The out-of-plane deformation can be quantified using two parameters: net change in surface area and the shape of deformation. Change in surface area depends on the voltage, while the deformation shape, which significantly affects the flow rate, is a function of voltage, and the pressure and volume of the chambers on each side of the thin plate. The use of solid electrodes enables a robust and reversible pumping mechanism that will have will enable advancements in rapid microfluidic diagnostics, adaptive materials, and artificial muscles.

Investigation of smoothness-increasing accuracy-conserving filters for improving streamline integration through discontinuous fields.

PubMed

Steffen, Michael; Curtis, Sean; Kirby, Robert M; Ryan, Jennifer K

2008-01-01

Streamline integration of fields produced by computational fluid mechanics simulations is a commonly used tool for the investigation and analysis of fluid flow phenomena. Integration is often accomplished through the application of ordinary differential equation (ODE) integrators--integrators whose error characteristics are predicated on the smoothness of the field through which the streamline is being integrated--smoothness which is not available at the inter-element level of finite volume and finite element data. Adaptive error control techniques are often used to ameliorate the challenge posed by inter-element discontinuities. As the root of the difficulties is the discontinuous nature of the data, we present a complementary approach of applying smoothness-enhancing accuracy-conserving filters to the data prior to streamline integration. We investigate whether such an approach applied to uniform quadrilateral discontinuous Galerkin (high-order finite volume) data can be used to augment current adaptive error control approaches. We discuss and demonstrate through numerical example the computational trade-offs exhibited when one applies such a strategy.

Control volume analyses of glottal flow using a fully-coupled numerical fluid-structure interaction model

NASA Astrophysics Data System (ADS)

Yang, Jubiao; Krane, Michael; Zhang, Lucy

2013-11-01

Vocal fold vibrations and the glottal jet are successfully simulated using the modified Immersed Finite Element method (mIFEM), a fully coupled dynamics approach to model fluid-structure interactions. A self-sustained and steady vocal fold vibration is captured given a constant pressure input at the glottal entrance. The flow rates at different axial locations in the glottis are calculated, showing small variations among them due to the vocal fold motion and deformation. To further facilitate the understanding of the phonation process, two control volume analyses, specifically with Bernoulli's equation and Newton's 2nd law, are carried out for the glottal flow based on the simulation results. A generalized Bernoulli's equation is derived to interpret the correlations between the velocity and pressure temporally and spatially along the center line which is a streamline using a half-space model with symmetry boundary condition. A specialized Newton's 2nd law equation is developed and divided into terms to help understand the driving mechanism of the glottal flow.

Pin stack array for thermoacoustic energy conversion

DOEpatents

Keolian, Robert M.; Swift, Gregory W.

1995-01-01

A thermoacoustic stack for connecting two heat exchangers in a thermoacoustic energy converter provides a convex fluid-solid interface in a plane perpendicular to an axis for acoustic oscillation of fluid between the two heat exchangers. The convex surfaces increase the ratio of the fluid volume in the effective thermoacoustic volume that is displaced from the convex surface to the fluid volume that is adjacent the surface within which viscous energy losses occur. Increasing the volume ratio results in an increase in the ratio of transferred thermal energy to viscous energy losses, with a concomitant increase in operating efficiency of the thermoacoustic converter. The convex surfaces may be easily provided by a pin array having elements arranged parallel to the direction of acoustic oscillations and with effective radial dimensions much smaller than the thicknesses of the viscous energy loss and thermoacoustic energy transfer volumes.

3D Volumetric Analysis of Fluid Inclusions Using Confocal Microscopy

NASA Astrophysics Data System (ADS)

Proussevitch, A.; Mulukutla, G.; Sahagian, D.; Bodnar, B.

2009-05-01

Fluid inclusions preserve valuable information regarding hydrothermal, metamorphic, and magmatic processes. The molar quantities of liquid and gaseous components in the inclusions can be estimated from their volumetric measurements at room temperatures combined with knowledge of the PVTX properties of the fluid and homogenization temperatures. Thus, accurate measurements of inclusion volumes and their two phase components are critical. One of the greatest advantages of the Laser Scanning Confocal Microscopy (LSCM) in application to fluid inclsion analsyis is that it is affordable for large numbers of samples, given the appropriate software analysis tools and methodology. Our present work is directed toward developing those tools and methods. For the last decade LSCM has been considered as a potential method for inclusion volume measurements. Nevertheless, the adequate and accurate measurement by LSCM has not yet been successful for fluid inclusions containing non-fluorescing fluids due to many technical challenges in image analysis despite the fact that the cost of collecting raw LSCM imagery has dramatically decreased in recent years. These problems mostly relate to image analysis methodology and software tools that are needed for pre-processing and image segmentation, which enable solid, liquid and gaseous components to be delineated. Other challenges involve image quality and contrast, which is controlled by fluorescence of the material (most aqueous fluid inclusions do not fluoresce at the appropriate laser wavelengths), material optical properties, and application of transmitted and/or reflected confocal illumination. In this work we have identified the key problems of image analysis and propose some potential solutions. For instance, we found that better contrast of pseudo-confocal transmitted light images could be overlayed with poor-contrast true-confocal reflected light images within the same stack of z-ordered slices. This approach allows one to narrow the interface boundaries between the phases before the application of segmentation routines. In turn, we found that an active contour segmentation technique works best for these types of geomaterials. The method was developed by adapting a medical software package implemented using the Insight Toolkit (ITK) set of algorithms developed for segmentation of anatomical structures. We have developed a manual analysis procedure with the potential of 2 micron resolution in 3D volume rendering that is specifically designed for application to fluid inclusion volume measurements.

Microfluidic valve with cored glass microneedle for microinjection.

PubMed

Lee, Sanghoon; Jeong, Wonje; Beebe, David J

2003-08-01

In this paper, a new microinjection device was constructed by fusing a glass microneedle and a PDMS-based microvalve. The microneedle was fabricated via traditional micropipette pulling. The PDMS-based microvalve regulates the fluid flow in the microchannel and microneedle. The 'ON/OFF' operation of the valve was controlled by manually supplied pneumatic pressure. The valve membrane utilized a two level geometry to improve control at low flow rates. The relation between pressure and flow was measured and the results showed that very small volumes of fluid (>1 nl) could be controlled. The valve operation was investigated by monitoring the tip of the needle and pneumatic pressure simultaneously and it demonstrated very stable 'ON/OFF' operation to the pressure change.

Effect of an eigenstrain on slow viscous flow of compressible fluid films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, P.E.

We present a general formulation of the mechanics of slow viscous flow of slightly compressible fluid films in the presence of an eigenstrain. An eigenstrain represents a constrained volume change due to temperature, concentration of a dissolved species, or a chemical transformation. A silicon dioxide film grown on a silicon surface is an example of a viscous fluid film that is affected by a constrained volume change. We obtain a general expression for pressure in a fluid film produced by a surface chemical reaction accompanied by a volume change. This result is used to study the effect of an eigenstrainmore » on viscous stress relaxation in fluid films.« less

Choice of the replacement fluid during large volume plasma-exchange.

PubMed

Nydegger, U E

1983-01-01

The replacement fluid used during therapeutic large volume plasma-exchange can be seen as an important factor influencing the result of such treatment. The choice includes fluids such as electrolyte solutions, gelatin, hydroxyethyl-starch, albumin and fresh frozen plasma. By evaluating the pathophysiology of the underlying disease, it is possible to choose between merely replacing the removed volume by non-protein fluids or rather to introduce plasma protein components into the patient's circulation by substituting with purified or enriched proteins such as albumin, clotting factors, antithrombin III or fresh frozen plasma. This paper analyzes the rationale for the choice of the appropriate replacement fluid taking into account pathophysiologic, pharmacologic and logistic criteria.

Determination of gas volume trapped in a closed fluid system

NASA Technical Reports Server (NTRS)

Hunter, W. F.; Jolley, J. E.

1971-01-01

Technique involves extracting known volume of fluid and measuring system before and after extraction, volume of entrapped gas is then computed. Formula derived from ideal gas laws is basis of this method. Technique is applicable to thermodynamic cycles and hydraulic systems.

Efficacy and Safety of Stroke Volume Variation-Guided Fluid Therapy for Reducing Blood Loss and Transfusion Requirements During Radical Cystectomy: A Randomized Clinical Trial.

PubMed

Kong, Yu-Gyeong; Kim, Ji Yoon; Yu, Jihion; Lim, Jinwook; Hwang, Jai-Hyun; Kim, Young-Kug

2016-05-01

Radical cystectomy, which is performed to treat muscle-invasive bladder tumors, is among the most difficult urological surgical procedures and puts patients at risk of intraoperative blood loss and transfusion. Fluid management via stroke volume variation (SVV) is associated with reduced intraoperative blood loss. Therefore, we evaluated the efficacy and safety of SVV-guided fluid therapy for reducing blood loss and transfusion requirements in patients undergoing radical cystectomy.This study included 48 patients who underwent radical cystectomy, and these patients were randomly allocated to the control group and maintained at <10% SVV (n = 24) or allocated to the trial group and maintained at 10% to 20% SVV (n = 24). The primary endpoints were comparisons of the amounts of intraoperative blood loss and transfused red blood cells (RBCs) between the control and trial groups during radical cystectomy. Intraoperative blood loss was evaluated through the estimated blood loss and estimated red cell mass loss. The secondary endpoints were comparisons of the postoperative outcomes between groups.A total of 46 patients were included in the final analysis: 23 patients in the control group and 23 patients in the trial group. The SVV values in the trial group were significantly higher than in the control group. Estimated blood loss, estimated red cell mass loss, and RBC transfusion requirements in the trial group were significantly lower than in the control group (734.3 ± 321.5 mL vs 1096.5 ± 623.9 mL, P = 0.019; 274.1 ± 207.8 mL vs 553.1 ± 298.7 mL, P <0.001; 0.5 ± 0.8 units vs 1.9 ± 2.2 units, P = 0.005). There were no significant differences in postoperative outcomes between the two groups.SVV-guided fluid therapy (SVV maintained at 10%-20%) can reduce blood loss and transfusion requirements in patients undergoing radical cystectomy without resulting in adverse outcomes. These findings provide useful information for optimal fluid management during radical cystectomy.

Myocardial, smooth muscle, nephron, and collecting duct gene targeting reveals the organ sites of endothelin A receptor antagonist fluid retention.

PubMed

Stuart, Deborah; Chapman, Mark; Rees, Sara; Woodward, Stephanie; Kohan, Donald E

2013-08-01

Endothelin-1 binding to endothelin A receptors (ETA) elicits profibrogenic, proinflammatory, and proliferative effects that can promote a wide variety of diseases. Although ETA antagonists are approved for the treatment of pulmonary hypertension, their clinical utility in several other diseases has been limited by fluid retention. ETA blocker-induced fluid retention could be due to inhibition of ETA activation in the heart, vasculature, and/or kidney; consequently, the current study was designed to define which of these sites are involved. Mice were generated with absence of ETA specifically in cardiomyocytes (heart), smooth muscle, the nephron, the collecting duct, or no deletion (control). Administration of the ETA antagonist ambrisentan or atrasentan for 2 weeks caused fluid retention in control mice on a high-salt diet as assessed by increases in body weight, total body water, and extracellular fluid volume (using impedance plethysmography), as well as decreases in hematocrit (hemodilution). Mice with heart ETA knockout retained fluid in a similar manner as controls when treated with ambrisentan or atrasentan. Mice with smooth muscle ETA knockout had substantially reduced fluid retention in response to either ETA antagonist. Mice with nephron or collecting duct ETA disruption were completely prevented from ETA blocker-induced fluid retention. Taken together, these findings suggest that ETA antagonist-induced fluid retention is due to a direct effect of this class of drug on the collecting duct, is partially related to the vascular action of the drugs, and is not due to alterations in cardiac function.

A Novel CO2-Responsive Viscoelastic Amphiphilic Surfactant Fluid for Fracking in Enhanced Oil/Gas Recovery

NASA Astrophysics Data System (ADS)

Zhong, L.; Wu, X.; Dai, C.

2017-12-01

Over the past decade, the rapid rise of unconventional shale gas and tight sandstone oil development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources. Hydraulic fracturing fluids play very important roles in enhanced oil/gas recovery. However, damage to the reservoir rock and environmental contamination caused by hydraulic fracturing flowback fluids has raised serious concerns. The development of reservoir rock friendly and environmental benign fracturing fluids is in immediate demand. Studies to improve properties of hydraulic fracturing fluids have found that viscoelastic surfactant (VES) fracturing fluid can increase the productivity of gas/oil and be efficiently extracted after fracturing. Compared to conventional polymer fracturing fluid, VES fracturing fluid has many advantages, such as few components, easy preparation, good proppant transport capacity, low damage to cracks and formations, and environment friendly. In this work, we are developing a novel CO2-responsive VES fracking fluid that can readily be reused. This fluid has a gelling-breaking process that can be easily controlled by the presence of CO2 and its pressure. We synthesized erucamidopropyl dimethylamine (EA) as a thickening agent for hydraulic fracturing fluid. The influence of temperature, presence of CO2 and pressure on the viscoelastic behavior of this fluid was then investigated through rheological measurements. The fracturing fluid performance and recycle property were lastly studied using core flooding tests. We expect this fluid finds applications not only in enhanced oil/gas recovery, but also in areas such as controlling groundwater pollution and microfluidics.

Methods for recovering a polar solvent from a fluid stream contaminated with at least one polar impurity

DOEpatents

Ginosar, Daniel M.; Wendt, Daniel S.

2012-11-13

A method of removing a polar solvent from a fluid volume contaminated with at least one polar impurity, such as a free fatty acid, is provided. The method comprises providing a fluid volume that includes at least one polar impurity dissolved in at least one solvent. The fluid volume is contacted with an expanding gas to remove the at least one solvent. The expanding gas may be dissolved into the at least one solvent in the fluid volume to form a gas-expanded solvent. The immiscibility of the polar impurities in the gas-expanded solvent enables separation of the polar impurities from the gas-expanded solvent. After separation of the polar impurities, at least one of the temperature and pressure may be reduced to separate the solvent from the expanding gas such that the clean solvent may be reused.

Early Fluid and Protein Shifts in Men During Water Immersion

NASA Technical Reports Server (NTRS)

Hinghofer-Szalkay, H.; Harrison, M. H.; Greenleaf, J. E.

1987-01-01

High precision blood and plasma densitometry was used to measure transvascular fluid shifts during water immersion to the neck. Six men (28-49 years) undertook 30 min of standing immersion in water at 35.0 +/- 0.2 C; immersion was preceded by 30 min control standing in air at 28 +/- 1 C. Blood was sampled from an antecubital catheter for determination of Blood Density (BD), Plasma Density (PD), Haematocrit (Ht), total Plasma Protein Concentration (PPC), and Plasma Albumin Concentration (PAC). Compared to control, significant decreases (p less than 0.01) in all these measures were observed after 20 min immersion. At 30 min, plasma volume had increased by 11.0 +/- 2.8%; the average density of the fluid shifted from extravascular fluid into the vascular compartment was 1006.3 g/l; albumin moved with the fluid and its albumin concentration was about one-third of the plasma protein concentration during early immersion. These calculations are based on the assumption that the F-cell ratio remained unchanged. No changes in erythrocyte water content during immersion were found. Thus, immersion-induced haemodilution is probably accompanied by protein (mainly albumin) augmentation which accompanies the intra-vascular fluid shift.

Residual stress at fluid interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, P.E.

We extend the Navier-Stokes equations to allow for residual stress in Newtonian fluids. A fluid, which undergoes a constrained volume change, will have residual stress. Corresponding to every constrained volume change is an eigenstrain. We present a method to include in the equations of fluid motion the eigenstrain that is a result of the presence in a fluid of a soluble chemical species. This method is used to calculate the residual stress associated with a chemical transformation. 9 refs., 1 fig.

Determining the IV fluids required for a ten day medical emergency on Space Station Freedom - Comparison of packaged vs. on-orbit produced solutions

NASA Technical Reports Server (NTRS)

Creager, Gerald J.; Lloyd, Charles W.

1991-01-01

To aid planning for the storage of supplies onboard Space Station Freedom, an estimate was made of the amount of intravenous (IV) fluid required to support a patient who has suffered a medical emergency for a period of up to 10 days. Six different medical scenarios were evaluated, and the volume of IV fluids required for each scenario was estimated. Up to 220 liters of fluid would be required to support a patient for all of the scenarios. When optimizing the volumes to support any single scenario, a total of 123 liters is required. Use of a water polishing system to produce sterile water for injection from potable supplies and on-station formulation of IV fluids results in a smaller mass and volume requirement for the Fluid Therapy Subsystem than carrying prepackaged bags of fluid.

Perioperative fluid therapy: defining a clinical algorithm between insufficient and excessive.

PubMed

Strunden, Mike S; Tank, Sascha; Kerner, Thoralf

2016-12-01

In the perioperative scenario, adequate fluid and volume therapy is a challenging task. Despite improved knowledge on the physiology of the vascular barrier function and its respective pathophysiologic disturbances during the perioperative process, clear-cut therapeutic principles are difficult to implement. Neglecting the physiologic basis of the vascular barrier and the cardiovascular system, numerous studies proclaiming different approaches to fluid and volume therapy do not provide a rationale, as various surgical and patient risk groups, and different fluid regimens combined with varying hemodynamic measures and variable algorithms led to conflicting results. This review refers to the physiologic basis and answers questions inseparably conjoined to a rational approach to perioperative fluid and volume therapy: Why does fluid get lost from the vasculature perioperatively? Whereto does it get lost? Based on current findings and rationale considerations, which fluid replacement algorithm could be implemented into clinical routine? Copyright © 2016 Elsevier Inc. All rights reserved.

Development of a high-resolution automatic digital (urine/electrolytes) flow volume and rate measurement system of miniature size

NASA Technical Reports Server (NTRS)

Liu, F. F.

1975-01-01

To aid in the quantitative analysis of man's physiological rhythms, a flowmeter to measure circadian patterns of electrolyte excretion during various environmental stresses was developed. One initial flowmeter was designed and fabricated, the sensor of which is the approximate size of a wristwatch. The detector section includes a special type of dielectric integrating type sensor which automatically controls, activates, and deactivates the flow sensor data output by determining the presence or absence of fluid flow in the system, including operation under zero-G conditions. The detector also provides qualitative data on the composition of the fluid. A compact electronic system was developed to indicate flow rate as well as total volume per release or the cumulative volume of several releases in digital/analog forms suitable for readout or telemetry. A suitable data readout instrument is also provided. Calibration and statistical analyses of the performance functions required of the flowmeter were also conducted.

Hemodiafiltration history, technology, and clinical results.

PubMed

Ronco, Claudio; Cruz, Dinna

2007-07-01

Hemodiafiltration (HDF) is an extracorporeal renal-replacement technique using a highly permeable membrane, in which diffusion and convection are conveniently combined to enhance solute removal in a wide spectrum of molecular weights. In this modality, ultrafiltration exceeds the desired fluid loss in the patient, and replacement fluid must be administered to achieve the target fluid balance. Over the years, various HDF variants have emerged, including acetate-free biofiltration, high-volume HDF, internal HDF, paired-filtration dialysis, middilution HDF, double high-flux HDF, push-pull HDF, and online HDF. Recent technology has allowed online production of large volumes of microbiologically ultrapure fluid for reinfusion, greatly simplifying the practice of HDF. Several advantages of HDF over purely diffusive hemodialysis techniques have been described in the literature, including a greater clearance of urea, phosphate, beta(2)-microglobulin and other larger solutes, reduction in dialysis hypotension, and improved anemia management. Although randomized controlled trials have failed to show a survival benefit of HDF, recent data from large observational studies suggest a positive effect of HDF on survival. This article provides a brief review of the history of HDF, the various HDF techniques, and summary of their clinical effects.

Comparison of lung protective ventilation strategies in a rabbit model of acute lung injury.

PubMed

Rotta, A T; Gunnarsson, B; Fuhrman, B P; Hernan, L J; Steinhorn, D M

2001-11-01

To determine the impact of different protective and nonprotective mechanical ventilation strategies on the degree of pulmonary inflammation, oxidative damage, and hemodynamic stability in a saline lavage model of acute lung injury. A prospective, randomized, controlled, in vivo animal laboratory study. Animal research facility of a health sciences university. Forty-six New Zealand White rabbits. Mature rabbits were instrumented with a tracheostomy and vascular catheters. Lavage-injured rabbits were randomized to receive conventional ventilation with either a) low peak end-expiratory pressure (PEEP; tidal volume of 10 mL/kg, PEEP of 2 cm H2O); b) high PEEP (tidal volume of 10 mL/kg, PEEP of 10 cm H2O); c) low tidal volume with PEEP above Pflex (open lung strategy, tidal volume of 6 mL/kg, PEEP set 2 cm H2O > Pflex); or d) high-frequency oscillatory ventilation. Animals were ventilated for 4 hrs. Lung lavage fluid and tissue samples were obtained immediately after animals were killed. Lung lavage fluid was assayed for measurements of total protein, elastase activity, tumor necrosis factor-alpha, and malondialdehyde. Lung tissue homogenates were assayed for measurements of myeloperoxidase activity and malondialdehyde. The need for inotropic support was recorded. Animals that received a lung protective strategy (open lung or high-frequency oscillatory ventilation) exhibited more favorable oxygenation and lung mechanics compared with the low PEEP and high PEEP groups. Animals ventilated by a lung protective strategy also showed attenuation of inflammation (reduced tracheal fluid protein, tracheal fluid elastase, tracheal fluid tumor necrosis factor-alpha, and pulmonary leukostasis). Animals treated with high-frequency oscillatory ventilation had attenuated oxidative injury to the lung and greater hemodynamic stability compared with the other experimental groups. Both lung protective strategies were associated with improved oxygenation, attenuated inflammation, and decreased lung damage. However, in this small-animal model of acute lung injury, an open lung strategy with deliberate hypercapnia was associated with significant hemodynamic instability.

Prenatal programming of renal salt wasting resets postnatal salt appetite, which drives food intake in the rat.

PubMed

Alwasel, Saleh H; Barker, David J P; Ashton, Nick

2012-03-01

Sodium retention has been proposed as the cause of hypertension in the LP rat (offspring exposed to a maternal low-protein diet in utero) model of developmental programming because of increased renal NKCC2 (Na+/K+/2Cl- co-transporter 2) expression. However, we have shown that LP rats excrete more rather than less sodium than controls, leading us to hypothesize that LP rats ingest more salt in order to maintain sodium balance. Rats were fed on either a 9% (low) or 18% (control) protein diet during pregnancy; male and female offspring were studied at 4 weeks of age. LP rats of both sexes held in metabolism cages excreted more sodium and urine than controls. When given water to drink, LP rats drank more and ate more food than controls, hence sodium intake matched excretion. However, when given a choice between saline and water to drink, the total volume of fluid ingested by LP rats fell to control levels, but the volume of saline taken was significantly larger [3.8±0.1 compared with 8.8±1.3 ml/24 h per 100 g of body weight in control and LP rats respectively; P<0.001]. Interestingly food intake also fell to control levels. Total body sodium content and ECF (extracellular fluid) volumes were greater in LP rats. These results show that prenatal programming of renal sodium wasting leads to a compensatory increase in salt appetite in LP rats. We speculate that the need to maintain salt homoeostasis following malnutrition in utero stimulates greater food intake, leading to accelerated growth and raised BP (blood pressure).

Separation and/or sequestration apparatus and methods

DOEpatents

Rieke, Peter C; Towne, Silas A; Coffey, Greg W; Appel, Aaron M

2015-02-03

Apparatus for separating CO.sub.2 from an electrolyte solution are provided. Example apparatus can include: a vessel defining an interior volume and configured to house an electrolyte solution; an input conduit in fluid communication with the interior volume; an output conduit in fluid communication with the interior volume; an exhaust conduit in fluid communication with the interior volume; and an anode located within the interior volume. Other example apparatus can include: an elongated vessel having two regions; an input conduit extending outwardly from the one region; an output conduit extending outwardly from the other region; an exhaust conduit in fluid communication with the one region; and an anode located within the one region. Methods for separating CO.sub.2 from an electrolyte solution are provided. Example methods can include: providing a CO.sub.2 rich electrolyte solution to a vessel containing an anode; and distributing hydrogen from the anode to acidify the electrolyte solution.

[Fluid management and cause of death during shock period in patients with severe burns or burns complicated by inhalation injury].

PubMed

Zhang, Ming-liang; Li, Chi; Ma, Chun-xu

2003-11-01

To explore fluid management and cause of death during shock period in severe burns or burns with inhalation injury. One hundred and twelve patients with severe burns or burn complicated by inhalation injury admitted to our hospital from 1991 to 2000 were analyzed. The fluid management and death conditions during shock period were discussed. The fluid volume for resuscitation could be described as follows: the total fluid volume was 2.2 ml/(%TBSA.kg) including colloid fluid 0.5 ml/(%TBSA.kg), crystalloid fluid 1 ml/(%TBSA.kg)and water 0.7 ml/(%TBSA.kg) during first 24 hours. The total fluid volume was 1.8 ml/(%TBSA.kg) including colloid fluid 0.4 ml/(%TBSA.kg), crystalloid fluid 0.7 ml/(%TBSA.kg) and water 0.7 ml/(%TBSA.kg) during second 24 hours. There were no difference in fluid management between burns and burns with inhalation injury. Seven patients died due to respiratory failure during shock period. Many fluid formula can provide guidance for resuscitation and it is very important that early fluid therapy should accord with concrete clinical conditions of patients in order to pass smoothly through shock period. Early fluid management is not different between burns and burns with inhalation injury.

Optics-Integrated Microfluidic Platforms for Biomolecular Analyses

PubMed Central

Bates, Kathleen E.; Lu, Hang

2016-01-01

Compared with conventional optical methods, optics implemented on microfluidic chips provide small, and often much cheaper ways to interrogate biological systems from the level of single molecules up to small model organisms. The optical probing of single molecules has been used to investigate the mechanical properties of individual biological molecules; however, multiplexing of these measurements through microfluidics and nanofluidics confers many analytical advantages. Optics-integrated microfluidic systems can significantly simplify sample processing and allow a more user-friendly experience; alignments of on-chip optical components are predetermined during fabrication and many purely optical techniques are passively controlled. Furthermore, sample loss from complicated preparation and fluid transfer steps can be virtually eliminated, a particularly important attribute for biological molecules at very low concentrations. Excellent fluid handling and high surface area/volume ratios also contribute to faster detection times for low abundance molecules in small sample volumes. Although integration of optical systems with classical microfluidic analysis techniques has been limited, microfluidics offers a ready platform for interrogation of biophysical properties. By exploiting the ease with which fluids and particles can be precisely and dynamically controlled in microfluidic devices, optical sensors capable of unique imaging modes, single molecule manipulation, and detection of minute changes in concentration of an analyte are possible. PMID:27119629

Well fluid isolation and sample apparatus and method

DOEpatents

Schalla, Ronald; Smith, Ronald M.; Hall, Stephen H.; Smart, John E.

1995-01-01

The present invention specifically permits purging and/or sampling of a well but only removing, at most, about 25% of the fluid volume compared to conventional methods and, at a minimum, removing none of the fluid volume from the well. The invention is an isolation assembly that is inserted into the well. The isolation assembly is designed so that only a volume of fluid between the outside diameter of the isolation assembly and the inside diameter of the well over a fluid column height from the bottom of the well to the top of the active portion (lower annulus) is removed. A seal may be positioned above the active portion thereby sealing the well and preventing any mixing or contamination of inlet fluid with fluid above the packer. Purged well fluid is stored in a riser above the packer. Ports in the wall of the isolation assembly permit purging and sampling of the lower annulus along the height of the active portion.

Magnetic Resonance Imaging Quantification of Fasted State Colonic Liquid Pockets in Healthy Humans.

PubMed

Murray, Kathryn; Hoad, Caroline L; Mudie, Deanna M; Wright, Jeff; Heissam, Khaled; Abrehart, Nichola; Pritchard, Susan E; Al Atwah, Salem; Gowland, Penny A; Garnett, Martin C; Amidon, Gregory E; Spiller, Robin C; Amidon, Gordon L; Marciani, Luca

2017-08-07

The rate and extent of drug dissolution and absorption from solid oral dosage forms is highly dependent on the volume of liquid in the gastrointestinal tract (GIT). However, little is known about the time course of GIT liquid volumes after drinking a glass of water (8 oz), particularly in the colon, which is a targeted site for both locally and systemically acting drug products. Previous magnetic resonance imaging (MRI) studies offered novel insights on GIT liquid distribution in fasted humans in the stomach and small intestine, and showed that freely mobile liquid in the intestine collects in fairly distinct regions or "pockets". Based on this previous pilot data, we hypothesized that (1) it is possible to quantify the time course of the volume and number of liquid pockets in the undisturbed colon of fasted healthy humans following ingestion of 240 mL, using noninvasive MRI methods; (2) the amount of freely mobile water in the fasted human colon is of the order of only a few milliliters. Twelve healthy volunteers fasted overnight and underwent fasted abdominal MRI scans before drinking 240 mL (∼8 fluid ounces) of water. After ingesting the water they were scanned at frequent intervals for 2 h. The images were processed to quantify freely mobile water in the total and regional colon: ascending, transverse, and descending. The fasted colon contained (mean ± SEM) 11 ± 5 pockets of resting liquid with a total volume of 2 ± 1 mL (average). The colonic fluid peaked at 7 ± 4 mL 30 min after the water drink. This peak fluid was distributed in 17 ± 7 separate liquid pockets in the colon. The regional analysis showed that pockets of free fluid were found primarily in the ascending colon. The interindividual variability was very high; the subjects showed a range of number of colonic fluid pockets from 0 to 89 and total colonic freely mobile fluid volume from 0 to 49 mL. This is the first study measuring the time course of the number, regional location, and volume of pockets of freely mobile liquid in the undisturbed colon of fasted humans after ingestion of a glass of water. Novel insights into the colonic fluid environment will be particularly relevant to improve our understanding and design of the in vivo performance of controlled release formulations targeted to the colon. The in vivo quantitative information presented here can be input into physiologically based mechanistic models of dissolution and absorption, and can be used in the design and set up of novel in vitro performance tools predictive of the in vivo environment.

Space flight affects magnocellular supraoptic neurons of young prepuberal rats: transient and permanent effects

NASA Technical Reports Server (NTRS)

Garcia-Ovejero, D.; Trejo, J. L.; Ciriza, I.; Walton, K. D.; Garcia-Segura, L. M.

2001-01-01

Effects of microgravity on postural control and volume of extracellular fluids as well as stress associated with space flight may affect the function of hypothalamic neurosecretory neurons. Since environmental modifications in young animals may result in permanent alterations in neuroendocrine function, the present study was designed to determine the effect of a space flight on oxytocinergic and vasopressinergic magnocellular hypothalamic neurons of prepuberal rats. Fifteen-day-old Sprague-Dawley female rats were flown aboard the Space Shuttle Columbia (STS-90, Neurolab mission, experiment 150) for 16 days. Age-matched litters remained on the ground in cages similar to those of the flight animals. Six animals from each group were killed on the day of landing and eight animals from each group were maintained under standard vivarium conditions and killed 18 weeks after landing. Several signs of enhanced transcriptional and biosynthetic activity were observed in magnocellular supraoptic neurons of flight animals on the day of landing compared to control animals. These include increased c-Fos expression, larger nucleoli and cytoplasm, and higher volume occupied in the neuronal perikaryon by mitochondriae, endoplasmic reticulum, Golgi apparatus, lysosomes and cytoplasmic inclusions known as nematosomes. In contrast, the volume occupied by neurosecretory vesicles in the supraoptic neuronal perikarya was significantly decreased in flight rats. This decrease was associated with a significant decrease in oxytocin and vasopressin immunoreactive levels, suggestive of an increased hormonal release. Vasopressin levels, cytoplasmic volume and c-Fos expression returned to control levels by 18 weeks after landing. These reversible effects were probably associated to osmotic stimuli resulting from modifications in the volume and distribution of extracellular fluids and plasma during flight and landing. However, oxytocin levels were still reduced at 18 weeks after landing in flight animals compared to controls. This indicates that space flight during prepuberal age may induce irreversible modifications in the regulation of oxytocinergic neurons, which in turn may result in permanent endocrine and behavioral impairments.

Characterization of seismic properties across scales: from the laboratory- to the field scale

NASA Astrophysics Data System (ADS)

Grab, Melchior; Quintal, Beatriz; Caspari, Eva; Maurer, Hansruedi; Greenhalgh, Stewart

2016-04-01

When exploring geothermal systems, the main interest is on factors controlling the efficiency of the heat exchanger. This includes the energy state of the pore fluids and the presence of permeable structures building part of the fluid transport system. Seismic methods are amongst the most common exploration techniques to image the deep subsurface in order to evaluate such a geothermal heat exchanger. They make use of the fact that a seismic wave caries information on the properties of the rocks in the subsurface through which it passes. This enables the derivation of the stiffness and the density of the host rock from the seismic velocities. Moreover, it is well-known that the seismic waveforms are modulated while propagating trough the subsurface by visco-elastic effects due to wave induced fluid flow, hence, delivering information about the fluids in the rock's pore space. To constrain the interpretation of seismic data, that is, to link seismic properties with the fluid state and host rock permeability, it is common practice to measure the rock properties of small rock specimens in the laboratory under in-situ conditions. However, in magmatic geothermal systems or in systems situated in the crystalline basement, the host rock is often highly impermeable and fluid transport predominately takes place in fracture networks, consisting of fractures larger than the rock samples investigated in the laboratory. Therefore, laboratory experiments only provide the properties of relatively intact rock and an up-scaling procedure is required to characterize the seismic properties of large rock volumes containing fractures and fracture networks and to study the effects of fluids in such fractured rock. We present a technique to parameterize fractured rock volumes as typically encountered in Icelandic magmatic geothermal systems, by combining laboratory experiments with effective medium calculations. The resulting models can be used to calculate the frequency-dependent bulk modulus K(ω) and shear modulus G(ω), from which the P- and S-wave velocities V P(ω) and V S(ω) and the quality factors QP(ω) and QS(ω) of fluid saturated fractured rock volumes can be estimated. These volumes are much larger and contain more complex structures than the rock samples investigated in the laboratory. Thus, the derived quantities describe the elastic and anelastic (energy loss due to wave induced fluid flow) short-term deformation induced by seismic waves at scales that are relevant for field-scale seismic exploration projects.

Numerical simulation of immiscible viscous fingering using adaptive unstructured meshes

NASA Astrophysics Data System (ADS)

Adam, A.; Salinas, P.; Percival, J. R.; Pavlidis, D.; Pain, C.; Muggeridge, A. H.; Jackson, M.

2015-12-01

Displacement of one fluid by another in porous media occurs in various settings including hydrocarbon recovery, CO2 storage and water purification. When the invading fluid is of lower viscosity than the resident fluid, the displacement front is subject to a Saffman-Taylor instability and is unstable to transverse perturbations. These instabilities can grow, leading to fingering of the invading fluid. Numerical simulation of viscous fingering is challenging. The physics is controlled by a complex interplay of viscous and diffusive forces and it is necessary to ensure physical diffusion dominates numerical diffusion to obtain converged solutions. This typically requires the use of high mesh resolution and high order numerical methods. This is computationally expensive. We demonstrate here the use of a novel control volume - finite element (CVFE) method along with dynamic unstructured mesh adaptivity to simulate viscous fingering with higher accuracy and lower computational cost than conventional methods. Our CVFE method employs a discontinuous representation for both pressure and velocity, allowing the use of smaller control volumes (CVs). This yields higher resolution of the saturation field which is represented CV-wise. Moreover, dynamic mesh adaptivity allows high mesh resolution to be employed where it is required to resolve the fingers and lower resolution elsewhere. We use our results to re-examine the existing criteria that have been proposed to govern the onset of instability.Mesh adaptivity requires the mapping of data from one mesh to another. Conventional methods such as consistent interpolation do not readily generalise to discontinuous fields and are non-conservative. We further contribute a general framework for interpolation of CV fields by Galerkin projection. The method is conservative, higher order and yields improved results, particularly with higher order or discontinuous elements where existing approaches are often excessively diffusive.

A budget of energy transfer in a sustained vocal folds vibration in glottis

NASA Astrophysics Data System (ADS)

Zhang, Lucy; Yang, Jubiao; Krane, Michael

2016-11-01

A set of force and energy balance equations using the control volume approach is derived based on the first principles of physics for a sustained vocal folds vibration in glottis. The control volume analysis is done for compressible airflow in a moving and deforming control volume in the vicinity of the vocal folds. The interaction between laryngeal airflow and vocal folds are successfully simulated using the modified Immersed Finite Element Method (mIFEM), a fully coupled approach to simulate fluid-structure interactions. Detailed mathematical terms are separated out for deeper physical understanding and utilization of mechanical energy is quantified with the derived equation. The results show that majority of energy input is consumed for driving laryngeal airflow, while a smaller portion is for compensating viscous losses in and sustaining the vibration of the vocal folds. We acknowledge the funding support of NIH 2R01DC005642-10A1.

Finite element analysis in fluids; Proceedings of the Seventh International Conference on Finite Element Methods in Flow Problems, University of Alabama, Huntsville, Apr. 3-7, 1989

NASA Technical Reports Server (NTRS)

Chung, T. J. (Editor); Karr, Gerald R. (Editor)

1989-01-01

Recent advances in computational fluid dynamics are examined in reviews and reports, with an emphasis on finite-element methods. Sections are devoted to adaptive meshes, atmospheric dynamics, combustion, compressible flows, control-volume finite elements, crystal growth, domain decomposition, EM-field problems, FDM/FEM, and fluid-structure interactions. Consideration is given to free-boundary problems with heat transfer, free surface flow, geophysical flow problems, heat and mass transfer, high-speed flow, incompressible flow, inverse design methods, MHD problems, the mathematics of finite elements, and mesh generation. Also discussed are mixed finite elements, multigrid methods, non-Newtonian fluids, numerical dissipation, parallel vector processing, reservoir simulation, seepage, shallow-water problems, spectral methods, supercomputer architectures, three-dimensional problems, and turbulent flows.

Ad libitum fluid consumption via self- or external administration.

PubMed

Yeargin, Susan W; Finn, Megan E; Eberman, Lindsey E; Gage, Matthew J; McDermott, Brendon P; Niemann, Andrew

2015-01-01

During team athletic events, athletic trainers commonly provide fluids with water bottles. When a limited number of water bottles exist, various techniques are used to deliver fluids. To determine whether fluid delivered via water-bottle administration influenced fluid consumption and hydration status. Crossover study. Outdoor field (22.2°C ± 3.5°C). Nineteen participants (14 men, 5 women, age = 30 ± 10 years, height = 176 ± 8 cm, mass = 72.5 ± 10 kg) were recruited from the university and local running clubs. The independent variable was fluid delivery with 3 levels: self-administration with mouth-to-bottle direct contact (SA-DC), self-administration with no contact between mouth and bottle (SA-NC), and external administration with no contact between the mouth and the bottle (EA-NC). Participants warmed up for 10 minutes before completing 5 exercise stations, after which an ad libitum fluid break was given, for a total of 6 breaks. We measured the fluid variables of total volume consumed, total number of squirts, and average volume per squirt. Hydration status via urine osmolality and body-mass loss, and perceptual variables for thirst and fullness were recorded. We calculated repeated-measures analyses of variance to assess hydration status, fluid variables, and perceptual measures to analyze conditions across time. The total volume consumed for EA-NC was lower than for SA-DC (P = .001) and SA-NC (P = .001). The total number of squirts for SA-DC was lower than for SA-NC (P = .009). The average volume per squirt for EA-NC was lower than for SA-DC (P = .020) and SA-NC (P = .009). Participants arrived (601.0 ± 21.3 mOsm/L) and remained (622.3 ± 38.3 mOsm/L) hydrated, with no difference between conditions (P = .544); however, the EA-NC condition lost more body mass than did the SA-DC condition (P = .001). There was no main effect for condition on thirst (P = .147) or fullness (P = .475). External administration of fluid decreased total volume consumed via a decreased average volume per squirt. The SA-DC method requires fewer squirts within a specific time frame. Fluid breaks every 15 minutes resulted in maintenance of euhydration; however, loss of body mass was influenced by fluid administration. Athletic trainers should avoid external administration to promote positive hydration behaviors. When fluid is self-administered, individual bottles may be the best clinical practice because more volume can be consumed per squirt.

Finasteride for chronic central serous chorioretinopathy.

PubMed

Forooghian, Farzin; Meleth, Annal D; Cukras, Catherine; Chew, Emily Y; Wong, Wai T; Meyerle, Catherine B

2011-04-01

To evaluate the safety and efficacy of finasteride, an inhibitor of dihydrotestosterone synthesis, in the treatment of chronic central serous chorioretinopathy. Five patients with chronic central serous chorioretinopathy were prospectively enrolled in this pilot study. Patients were administered finasteride (5 mg) daily for 3 months, after which study medication was withheld and patients were observed for 3 months. Main outcome measures included best-corrected visual acuity, central subfield macular thickness, and subretinal fluid volume as assessed by optical coherence tomography. Serum dihydrotestosterone, serum testosterone, and urinary cortisol were also measured. There was no change in mean best-corrected visual acuity. Mean center-subfield macular thickness and subretinal fluid volume reached a nadir at 3 months and rose to levels that were below baseline by 6 months. The changes in both optical coherence tomography parameters paralleled those in serum dihydrotestosterone level. In four patients, center-subfield macular thickness and/or subretinal fluid volume increased after discontinuation of finasteride. In the remaining patient, both optical coherence tomography parameters normalized with finasteride and remained stable when the study medication was discontinued. Finasteride may represent a novel medical treatment for chronic central serous chorioretinopathy. Larger controlled clinical trials are needed to further assess the efficacy of finasteride for the treatment of central serous chorioretinopathy.

Finasteride for Chronic Central Serous Chorioretinopathy

PubMed Central

Forooghian, Farzin; Meleth, Annal D.; Cukras, Catherine; Chew, Emily Y.; Wong, Wai T.; Meyerle, Catherine B.

2010-01-01

Purpose To evaluate the safety and efficacy of finasteride, an inhibitor of dihyroxytestosterone (DHT) synthesis, in the treatment of chronic central serous chorioretinopathy (CSC). Methods Five patients with chronic CSC were prospectively enrolled in this pilot study. Patients were administered finasteride (5mg) daily for 3 months, following which study medication was withheld and patients were observed for 3 months. Main outcome measures included best-corrected visual acuity (BCVA), center-subfield macular thickness and subretinal fluid volume as assessed by optical coherence tomography (OCT). Serum DHT, serum testosterone, and urinary cortisol were also measured. Results There was no change in mean BCVA. Mean center-subfield macular thickness and subretinal fluid volume reached a nadir at 3 months, and rose to levels that were below baseline by 6 months. The changes in both OCT parameters paralleled changes in serum DHT level. In four patients, center-subfield macular thickness and/or subretinal fluid volume increased following discontinuation of finasteride. In the remaining patient, both OCT parameters normalized with finasteride and remained stable when the study medication was discontinued. Conclusion Finasteride may represent a novel medical treatment for chronic CSC. Larger controlled clinical trials are needed to further assess the efficacy of finasteride for the treatment of CSC. Summary Pilot study to evaluate finasteride for treatment of chronic central serous chorioretinopathy suggests efficacy and tolerability. PMID:21273946

Microfluidic device and method for focusing, segmenting, and dispensing of a fluid stream

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN

2008-09-09

A microfluidic device and method for forming and dispensing minute volume segments of a material are described. In accordance with the present invention, a microfluidic device and method are provided for spatially confining the material in a focusing element. The device is also adapted for segmenting the confined material into minute volume segments, and dispensing a volume segment to a waste or collection channel. The device further includes means for driving the respective streams of sample and focusing fluids through respective channels into a chamber, such that the focusing fluid streams spatially confine the sample material. The device may also include additional means for driving a minute volume segment of the spatially confined sample material into a collection channel in fluid communication with the waste reservoir.

Microfluidic device and method for focusing, segmenting, and dispensing of a fluid stream

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2004-09-14

A microfluidic device for forming and/or dispensing minute volume segments of a material is described. In accordance with one aspect of the present invention, a microfluidic device and method is provided for spatially confining the material in a focusing element. The device is also capable of segmenting the confined material into minute volume segments, and dispensing a volume segment to a waste or collection channel. The device further includes means for driving the respective streams of sample and focusing fluids through respective channels into a chamber, such that the focusing fluid streams spatially confine the sample material. The device may also include additional means for driving a minute volume segment of the spatially confined sample material into a collection channel in fluid communication with the waste reservoir.

Anthropogenic seismicity rates and operational parameters at the Salton Sea Geothermal Field.

PubMed

Brodsky, Emily E; Lajoie, Lia J

2013-08-02

Geothermal power is a growing energy source; however, efforts to increase production are tempered by concern over induced earthquakes. Although increased seismicity commonly accompanies geothermal production, induced earthquake rate cannot currently be forecast on the basis of fluid injection volumes or any other operational parameters. We show that at the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. After correcting for the aftershock rate, the net fluid volume (extracted-injected) provides the best correlation with seismicity in recent years. We model the background earthquake rate with a linear combination of injection and net production rates that allows us to track the secular development of the field as the number of earthquakes per fluid volume injected decreases over time.

Feet swelling in a multistage ultraendurance triathlete: a case study

PubMed Central

Knechtle, Beat; Zingg, Matthias Alexander; Knechtle, Patrizia; Rosemann, Thomas; Rüst, Christoph Alexander

2015-01-01

Recent studies investigating ultraendurance athletes showed an association between excessive fluid intake and swelling of the lower limbs such as the feet. To date, this association has been investigated in single-stage ultraendurance races, but not in multistage ultraendurance races. In this case study, we investigated a potential association between fluid intake and feet swelling in a multistage ultraendurance race such as a Deca Iron ultratriathlon with ten Ironman triathlons within 10 consecutive days. A 49-year-old well-experienced ultratriathlete competed in autumn 2013 in the Deca Iron ultratriathlon held in Lonata del Garda, Italy, and finished the race as winner within 129:33 hours:minutes. Changes in body mass (including body fat and lean body mass), foot volume, total body water, and laboratory measurements were assessed. Food and fluid intake during rest and competing were recorded, and energy and fluid turnovers were estimated. During the ten stages, the volume of the feet increased, percentage body fat decreased, creatinine and urea levels increased, hematocrit and hemoglobin values decreased, and plasma [Na+] remained unchanged. The increase in foot volume was significantly and positively related to fluid intake during the stages. The poststage volume of the foot was related to poststage total body water, poststage creatinine, and poststage urea. This case report shows that the volume of the foot increased during the ten stages, and the increase in volume was significantly and positively related to fluid intake during the stages. Furthermore, the poststage volume of the foot was related to poststage total body water, poststage creatinine, and poststage urea. The continuous feet swelling during the race was most probably due to a combination of a high fluid intake and a progressive decline in renal function (ie, continuous increase in creatinine and urea), leading to body fluid retention (ie, increase in total body water). PMID:26508884

The Renal Renin-Angiotensin System

ERIC Educational Resources Information Center

Harrison-Bernard, Lisa M.

2009-01-01

The renin-angiotensin system (RAS) is a critical regulator of sodium balance, extracellular fluid volume, vascular resistance, and, ultimately, arterial blood pressure. In the kidney, angiotensin II exerts its effects to conserve salt and water through a combination of the hemodynamic control of renal blood flow and glomerular filtration rate and…

The effects of goal-directed fluid therapy based on dynamic parameters on post-surgical outcome: a meta-analysis of randomized controlled trials.

PubMed

Benes, Jan; Giglio, Mariateresa; Brienza, Nicola; Michard, Frederic

2014-10-28

Dynamic predictors of fluid responsiveness, namely systolic pressure variation, pulse pressure variation, stroke volume variation and pleth variability index have been shown to be useful to identify in advance patients who will respond to a fluid load by a significant increase in stroke volume and cardiac output. As a result, they are increasingly used to guide fluid therapy. Several randomized controlled trials have tested the ability of goal-directed fluid therapy (GDFT) based on dynamic parameters (GDFTdyn) to improve post-surgical outcome. These studies have yielded conflicting results. Therefore, we performed this meta-analysis to investigate whether the use of GDFTdyn is associated with a decrease in post-surgical morbidity. A systematic literature review, using MEDLINE, EMBASE, and The Cochrane Library databases through September 2013 was conducted. Data synthesis was obtained by using odds ratio (OR) and weighted mean difference (WMD) with 95% confidence interval (CI) by random-effects model. In total, 14 studies met the inclusion criteria (961 participants). Post-operative morbidity was reduced by GDFTdyn (OR 0.51; CI 0.34 to 0.75; P <0.001). This effect was related to a significant reduction in infectious (OR 0.45; CI 0.27 to 0.74; P = 0.002), cardiovascular (OR 0.55; CI 0.36 to 0.82; P = 0.004) and abdominal (OR 0.56; CI 0.37 to 0.86; P = 0.008) complications. It was associated with a significant decrease in ICU length of stay (WMD -0.75 days; CI -1.37 to -0.12; P = 0.02). In surgical patients, we found that GDFTdyn decreased post-surgical morbidity and ICU length of stay. Because of the heterogeneity of studies analyzed, large prospective clinical trials would be useful to confirm our findings.

The Effect of Water Loading on Acute Weight Loss Following Fluid Restriction in Combat Sports Athletes.

PubMed

Reale, Reid; Slater, Gary; Cox, Gregory R; Dunican, Ian C; Burke, Louise M

2018-05-03

Novel methods of acute weight loss practiced by combat sport athletes include "water loading," the consumption of large fluid volumes for several days prior to restriction. We examined claims that this technique increases total body water losses, while also assessing the risk of hyponatremia. Male athletes were separated into control (n = 10) and water loading (n = 11) groups and fed a standardized energy-matched diet for 6 days. Days 1-3 fluid intake was 40 and 100 ml/kg for control and water loading groups, respectively, with both groups consuming 15 ml/kg on Day 4 and following the same rehydration protocol on Days 5 and 6. We tracked body mass (BM), urine sodium, urine specific gravity and volume, training-related sweat losses and blood concentrations of renal hormones, and urea and electrolytes throughout. Physical performance was assessed preintervention and postintervention. Following fluid restriction, there were substantial differences between groups in the ratio of fluid input/output (39%, p < .01, effect size = 1.2) and BM loss (0.6% BM, p = .02, effect size = 0.82). Changes in urine specific gravity, urea and electrolytes, and renal hormones occurred over time (p < .05), with an interaction of time and intervention on blood sodium, potassium, chloride, urea, creatinine, urine specific gravity, and vasopressin (p < .05). Measurements of urea and electrolyte remained within reference ranges, and no differences in physical performance were detected over time or between groups. Water loading appears to be a safe and effective method of acute BM loss under the conditions of this study. Vasopressin-regulated changes in aquaporin channels may potentially partially explain the mechanism of increased body water loss with water loading.

High altitude haemofiltration.

PubMed

Stevens, P E; Bloodworth, L L; Rainford, D J

1986-05-24

Evacuating people in acute renal failure by air is difficult because the hazards of fluid overload and anaemia are potentiated by altitude. In two such patients continuous arteriovenous haemofiltration was used to control their fluid problems during aeromedical evacuation. In the first case, a patient with renal failure and blast lung, haemofiltration was performed at 500 ml/h over a four hour journey; in the second, a woman with severe pre-eclamptic toxaemia who developed acute renal failure after caesarean section, haemofiltration was performed at 200 ml/h over a 14 hour flight. Both patients recovered fully. In these two cases haemofiltration permitted control of the intravascular volume during aeromedical evacuation. The technique represents a major advance in the safe transfer of casualties.

Fornix Under Water? Ventricular Enlargement Biases Forniceal Diffusion Magnetic Resonance Imaging Indices in Anorexia Nervosa.

PubMed

Kaufmann, Lisa-Katrin; Baur, Volker; Hänggi, Jürgen; Jäncke, Lutz; Piccirelli, Marco; Kollias, Spyros; Schnyder, Ulrich; Pasternak, Ofer; Martin-Soelch, Chantal; Milos, Gabriella

2017-07-01

Acute anorexia nervosa (AN) is characterized by reduced brain mass and corresponding increased sulcal and ventricular cerebrospinal fluid. Recent studies of white matter using diffusion tensor imaging consistently identified alterations in the fornix, such as reduced fractional anisotropy (FA). However, because the fornix penetrates the ventricles, it is prone to cerebrospinal fluid-induced partial volume effects that interfere with a valid assessment of FA. We investigated the hypothesis that in the acute stage of AN, FA of the fornix is markedly affected by ventricular volumes. First, using diffusion tensor imaging data we established the inverse associations between forniceal FA and volumes of the third and lateral ventricles in a prestudy with 32 healthy subjects to demonstrate the strength of ventricular influence on forniceal FA independent of AN. Second, we investigated a sample of 25 acute AN patients and 25 healthy control subjects. Using ventricular volumes as covariates markedly reduced the group effect of forniceal FA, even with tract-based spatial statistics focusing only on the center of the fornix. In addition, after correcting for free water on voxel level, the group differences in forniceal FA between AN patients and controls disappeared completely. It is unlikely that microstructural changes affecting FA occurred in the fornix of AN patients. Previously identified alterations in acute AN may have been biased by partial volume effects and the proposed central role of this structure in the pathophysiology may need to be reconsidered. Future studies on white matter alterations in AN should carefully deal with partial volume effects. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

The rotating heat pipe - Implementation as a uniform-temperature heat source

NASA Astrophysics Data System (ADS)

Limoges, R. F.

1981-11-01

A wickless rotating heat pipe, if properly controlled, is a uniform heat source. The data presented are based on work done with 12.7 cm diameter x 76 cm long rotating heat pipes operating between 120 and 140 C. The major areas reviewed are: materials of fabrication, working fluids, sealing, temperature control, heaters, and safety. The optimum rotating heat pipe defined by these studies is fabricated of type 304 stainless steel, uses water as the working fluid, is sealed with welded joints, and utilizes a pressure switch and a fast-response quartz lamp for temperature control. Surface-temperature control of + or - 0.15 C and temperature uniformity within 0.8 C are obtained. Results of experiments designed to study the effects of hydrogen in the enclosed volume of the heat pipe are presented.

Implementation and effects of pulse-contour- automated SVV/CI guided goal directed fluid therapy algorithm for the routine management of pancreatic surgery patients.

PubMed

Kratz, Thomas; Simon, Christina; Fendrich, Volker; Schneider, Ralph; Wulf, Hinnerk; Kratz, Caroline; Efe, Turgay; Schüttler, Karl F; Zoremba, Martin

2016-11-14

Goal directed fluid management in major abdominal surgery has shown to reduce perioperative complications. The approach aims to optimize the intravascular fluid volume by use of minimally invasive devices which calculate flow-directed variables such as stroke volume (SV) and stroke volume variation (SVV). We aimed to show the feasibility of routinely implementing this type of hemodynamic monitoring during pancreatic surgery, and to evaluate its effects in terms of perioperative fluid management and postoperative outcomes. All patients undergoing pancreatic surgery at a university hospital during two successive 12 months periods were included in this retrospective cohort analysis. Twelve months after the implementation of a standard operating procedure for a goal directed therapy (GDT, N = 45) using a pulse contour automated hemodynamic device were compared with a similar period before its use (control, N = 31) regarding mortality, length of hospital and ICU stay, postoperative complications and the use of fluids and vasopressors. Overall, 76 patients were analysed. Significantly less crystalloids were used in the GDT group. Patients receiving GDT showed significantly fewer severe complications (insufficiency of intestinal anastomosis: 0 vs. 5 (P = 0.0053) and renal failure: 0 vs. 4 (P = 0.0133). Mortality for pancreatic surgery was 1 vs. 3 patients, (P = 0.142), and length of stay (LOS) in the intensive care unit (ICU) was 4.38 ± 3.63 vs. 6.87 ± 10.02 (P= 0.0964) days. Use of blood products was significantly less within the GDT group. Implementation of a SOP for a GDT in the daily routine using flow-related parameters is feasible and is associated with better outcomes in pancreatic surgery.

Kinetics of reciprocating drug delivery to the inner ear.

PubMed

Pararas, Erin E Leary; Chen, Zhiqiang; Fiering, Jason; Mescher, Mark J; Kim, Ernest S; McKenna, Michael J; Kujawa, Sharon G; Borenstein, Jeffrey T; Sewell, William F

2011-06-10

Reciprocating drug delivery is a means of delivering soluble drugs directly to closed fluid spaces in the body via a single cannula without an accompanying fluid volume change. It is ideally suited for drug delivery into small, sensitive and unique fluid spaces such as the cochlea. We characterized the pharmacokinetics of reciprocating drug delivery to the scala tympani within the cochlea by measuring the effects of changes in flow parameters on the distribution of drug throughout the length of the cochlea. Distribution was assessed by monitoring the effects of DNQX, a reversible glutamate receptor blocker, delivered directly to the inner ear of guinea pigs using reciprocating flow profiles. We then modeled the effects of those parameters on distribution using both an iterative curve-fitting approach and a computational fluid dynamic model. Our findings are consistent with the hypothesis that reciprocating delivery distributes the drug into a volume in the base of the cochlea, and suggest that the primary determinant of distribution throughout more distal regions of the cochlea is diffusion. Increases in flow rate distributed the drug into a larger volume that extended more apically. Over short time courses (less than 2h), the apical extension, though small, significantly enhanced apically directed delivery of drug. Over longer time courses (>5h) or greater distances (>3mm), maintenance of drug concentration in the basal scala tympani may prove more advantageous for extending apical delivery than increases in flow rate. These observations demonstrate that this reciprocating technology is capable of providing controlled delivery kinetics to the closed fluid space in the cochlea, and may be suitable for other applications such as localized brain and retinal delivery. Copyright © 2011 Elsevier B.V. All rights reserved.

Kinetics of Reciprocating Drug Delivery to the Inner Ear

PubMed Central

Leary Pararas, Erin E.; Chen, Zhiqiang; Fiering, Jason; Mescher, Mark J.; Kim, Ernest S.; McKenna, Michael J.; Kujawa, Sharon G.; Borenstein, Jeffrey T.; Sewell, William F.

2011-01-01

Reciprocating drug delivery is a means of delivering soluble drugs directly to closed fluid spaces in the body via a single cannula without an accompanying fluid volume change. It is ideally suited for drug delivery into small, sensitive and unique fluid spaces such as the cochlea. We characterized the pharmacokinetics of reciprocating drug delivery to the scala tympani within the cochlea by measuring the effects of changes in flow parameters on the distribution of drug throughout the length of the cochlea. Distribution was assessed by monitoring the effects of DNQX, a reversible glutamate receptor blocker, delivered directly to the inner ear of guinea pigs using reciprocating flow profiles. We then modeled the effects of those parameters on distribution using both an iterative curve-fitting approach and a computational fluid dynamic model. Our findings are consistent with the hypothesis that reciprocating delivery distributes the drug into a volume in the base of the cochlea, and suggest that the primary determinant of distribution throughout more distal regions of the cochlea is diffusion. Increases in flow rate distributed the drug into a larger volume that extended more apically. Over short time courses (less than 2 h), the apical extension, though small, significantly enhanced apically directed delivery of drug. Over longer time courses (>5 h) or greater distances (>3 mm), maintenance of drug concentration in the basal scala tympani may prove more advantageous for extending apical delivery than increases in flow rate. These observations demonstrate that this reciprocating technology is capable of providing controlled delivery kinetics to the closed fluid space in the cochlea, and may be suitable for other applications such as localized brain and retinal delivery. PMID:21385596

Sex dependence of brain size and shape in bipolar disorder: an exploratory study.

PubMed

Mackay, Clare E; Roddick, Elina; Barrick, Thomas R; Lloyd, Adrian J; Roberts, Neil; Crow, Tim J; Young, Allan H; Ferrier, I Nicol

2010-05-01

Anomalies of asymmetry and sex differences in brain structure have frequently been described in schizophrenic illnesses but have seldom been explored in bipolar disorder. We measured volumes of the left and right frontal, temporal, parietal, and occipital lobes and computed the magnitude of brain torque (i.e., rightward frontal and leftward occipital asymmetry) for 49 patients with bipolar disorder and 47 healthy controls and performed an exploratory analysis of sex differences in patients and controls. Patients had significantly greater cerebrospinal fluid volume than controls, but no difference in total brain volume. There were no main effects of diagnosis in gray matter lobe volume or brain torque, but when analyses were performed separately for male and female subjects, significant sex-by-diagnosis interactions were found in the volume of the left frontal, left temporal, right parietal, and right occipital lobes, such that male patients with bipolar disorder tend toward larger, more symmetric brains than male controls, whereas female patients tend toward smaller, more asymmetric brains than female controls. The lateralised nature of these interactions was such that the normal sex difference in volume was significantly accentuated, whilst the normal sex difference in asymmetry tended to be diminished in patients with bipolar disorder. We conclude that bipolar disorder in part reflects an interaction between brain growth and sex along the anterior-posterior axis of the human brain.

Fluid balance concepts in medicine: Principles and practice

PubMed Central

Roumelioti, Maria-Eleni; Glew, Robert H; Khitan, Zeid J; Rondon-Berrios, Helbert; Argyropoulos, Christos P; Malhotra, Deepak; Raj, Dominic S; Agaba, Emmanuel I; Rohrscheib, Mark; Murata, Glen H; Shapiro, Joseph I; Tzamaloukas, Antonios H

2018-01-01

The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water (TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment (mainly sodium salts) and in the intracellular compartment (mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume (EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in severe illness merits a separate third concept of body fluid balance. PMID:29359117

An Application of Cartesian-Grid and Volume-of-Fluid Methods to Numerical Ship Hydrodynamics

DTIC Science & Technology

2007-10-01

water-particle ve- locity is discontinuous across the air-water interface, and where CiEA is the Levi - Civita function. rj is the moment the vertical...methods and volume-of- immersed- body and volume-of-fluid (VOF) methods. fluid methods is used to simulate breaking waves around The governing equations are...of a ship hull is used as input to automat- body -fitted grids. The sole geometric input into NFA ically generate an immersed-boundary representation of

A pragmatic multi-centre randomised controlled trial of fluid loading in high-risk surgical patients undergoing major elective surgery--the FOCCUS study.

PubMed

Cuthbertson, Brian H; Campbell, Marion K; Stott, Stephen A; Elders, Andrew; Hernández, Rodolfo; Boyers, Dwayne; Norrie, John; Kinsella, John; Brittenden, Julie; Cook, Jonathan; Rae, Daniela; Cotton, Seonaidh C; Alcorn, David; Addison, Jennifer; Grant, Adrian

2011-01-01

Fluid strategies may impact on patient outcomes in major elective surgery. We aimed to study the effectiveness and cost-effectiveness of pre-operative fluid loading in high-risk surgical patients undergoing major elective surgery. This was a pragmatic, non-blinded, multi-centre, randomised, controlled trial. We sought to recruit 128 consecutive high-risk surgical patients undergoing major abdominal surgery. The patients underwent pre-operative fluid loading with 25 ml/kg of Ringer's solution in the six hours before surgery. The control group had no pre-operative fluid loading. The primary outcome was the number of hospital days after surgery with cost-effectiveness as a secondary outcome. A total of 111 patients were recruited within the study time frame in agreement with the funder. The median pre-operative fluid loading volume was 1,875 ml (IQR 1,375 to 2,025) in the fluid group compared to 0 (IQR 0 to 0) in controls with days in hospital after surgery 12.2 (SD 11.5) days compared to 17.4 (SD 20.0) and an adjusted mean difference of 5.5 days (median 2.2 days; 95% CI -0.44 to 11.44; P = 0.07). There was a reduction in adverse events in the fluid intervention group (P = 0.048) and no increase in fluid based complications. The intervention was less costly and more effective (adjusted average cost saving: £2,047; adjusted average gain in benefit: 0.0431 quality adjusted life year (QALY)) and has a high probability of being cost-effective. Pre-operative intravenous fluid loading leads to a non-significant reduction in hospital length of stay after high-risk major surgery and is likely to be cost-effective. Confirmatory work is required to determine whether these effects are reproducible, and to confirm whether this simple intervention could allow more cost-effective delivery of care. Prospective Clinical Trials, ISRCTN32188676.

A pragmatic multi-centre randomised controlled trial of fluid loading in high-risk surgical patients undergoing major elective surgery - the FOCCUS study

PubMed Central

2011-01-01

Introduction Fluid strategies may impact on patient outcomes in major elective surgery. We aimed to study the effectiveness and cost-effectiveness of pre-operative fluid loading in high-risk surgical patients undergoing major elective surgery. Methods This was a pragmatic, non-blinded, multi-centre, randomised, controlled trial. We sought to recruit 128 consecutive high-risk surgical patients undergoing major abdominal surgery. The patients underwent pre-operative fluid loading with 25 ml/kg of Ringer's solution in the six hours before surgery. The control group had no pre-operative fluid loading. The primary outcome was the number of hospital days after surgery with cost-effectiveness as a secondary outcome. Results A total of 111 patients were recruited within the study time frame in agreement with the funder. The median pre-operative fluid loading volume was 1,875 ml (IQR 1,375 to 2,025) in the fluid group compared to 0 (IQR 0 to 0) in controls with days in hospital after surgery 12.2 (SD 11.5) days compared to 17.4 (SD 20.0) and an adjusted mean difference of 5.5 days (median 2.2 days; 95% CI -0.44 to 11.44; P = 0.07). There was a reduction in adverse events in the fluid intervention group (P = 0.048) and no increase in fluid based complications. The intervention was less costly and more effective (adjusted average cost saving: £2,047; adjusted average gain in benefit: 0.0431 quality adjusted life year (QALY)) and has a high probability of being cost-effective. Conclusions Pre-operative intravenous fluid loading leads to a non-significant reduction in hospital length of stay after high-risk major surgery and is likely to be cost-effective. Confirmatory work is required to determine whether these effects are reproducible, and to confirm whether this simple intervention could allow more cost-effective delivery of care. Trial registration Prospective Clinical Trials, ISRCTN32188676 PMID:22177541

Particulate and microbial contamination in in-use admixed intravenous infusions.

PubMed

Yorioka, Katsuhiro; Oie, Shigeharu; Oomaki, Masafumi; Imamura, Akihisa; Kamiya, Akira

2006-11-01

We compared particulate and microbial contamination in residual solutions of peripheral intravenous admixtures after the termination of drip infusion between intravenous fluids admixed with glass ampoule drugs and those admixed with pre-filled syringe drugs. The mean number of particles>or=1.3 microm in diameter per 1 ml of residual solution was 758.4 for fluids (n=60) admixed with potassium chloride in a glass ampoule (20 ml volume), 158.6 for fluids (n=63) admixed with potassium chloride in a pre-filled syringe (20 ml volume), 736.5 for fluids (n=66) admixed with sodium chloride in a glass ampoule (20 ml volume), 179.2 for fluids (n=15) admixed with sodium chloride in a pre-filled syringe (20 ml volume), 1884.5 in fluids (n=30) admixed with dobutamine hydrochloride in 3 glass ampoules (5 ml volume), and 178.9 (n=10) in diluted dobutamine hydrochloride in pre-filled syringes (50 ml volume: For these samples alone, particulate and microbial contamination were evaluated in sealed products.) Thus, for potassium chloride or sodium chloride for injection, the number of particles>or=1.3 microm in diameter in the residual intravenous solution was significantly higher for fluids admixed with glass ampoule drugs than for those admixed with pre-filled syringe drugs (p<0.0001). For dobutamine hydrochloride for injection, the number of particles>or=1.3 microm in diameter in the residual intravenous solution was estimated to be higher for fluids admixed with its glass ampoule drug than for those admixed with its pre-filled syringe drug. Observation of the residual solutions of fluids admixed with potassium chloride, sodium chloride, or dobutamine hydrochloride in glass ampoules using an electron microscope with an X-ray analyzer showed glass fragments in each residual solution. Therefore, for the prevention of glass particle contamination in peripheral intravenous admixtures, the use of pre-filled syringe drugs may a useful method. No microbial contamination was observed in any of the residual solutions of 5 types of admixture.

Wettability effect on capillary trapping of supercritical CO2 at pore-scale: micromodel experiment and numerical modeling

NASA Astrophysics Data System (ADS)

Hu, R.; Wan, J.

2015-12-01

Wettability of reservoir minerals along pore surfaces plays a controlling role in capillary trapping of supercritical (sc) CO2 in geologic carbon sequestration. The mechanisms controlling scCO2 residual trapping are still not fully understood. We studied the effect of pore surface wettability on CO2 residual saturation at the pore-scale using engineered high pressure and high temperature micromodel (transparent pore networks) experiments and numerical modeling. Through chemical treatment of the micromodel pore surfaces, water-wet, intermediate-wet, and CO2-wet micromodels can be obtained. Both drainage and imbibition experiments were conducted at 8.5 MPa and 45 °C with controlled flow rate. Dynamic images of fluid-fluid displacement processes were recorded using a microscope with a CCD camera. Residual saturations were determined by analysis of late stage imbibition images of flow path structures. We performed direct numerical simulations of the full Navier-Stokes equations using a volume-of-fluid based finite-volume framework for the primary drainage and the followed imbibition for the micromodel experiments with different contact angles. The numerical simulations agreed well with our experimental observations. We found that more scCO2 can be trapped within the CO2-wet micromodel whereas lower residual scCO2 saturation occurred within the water-wet micromodels in both our experiments and the numerical simulations. These results provide direct and consistent evidence of the effect of wettability, and have important implications for scCO2 trapping in geologic carbon sequestration.

Factors influencing the restoration of fluid and electrolyte balance after exercise in the heat.

PubMed Central

Maughan, R J; Leiper, J B; Shirreffs, S M

1997-01-01

Maintenance of fluid balance is a major concern for all athletes competing in events held in hot climates. This paper reviews recent work relating to optimisation of fluid replacement after sweat loss induced by exercising in the heat. Data are taken from studies undertaken in our laboratory. Issues investigated were drink composition, volume consumed, effects of consuming food with a drink, effects of alcohol in rehydration effectiveness, voluntary intake of fluid, and considerations for women related to the menstrual cycle. The results are presented as a series of summaries of experiments, followed by a discussion of the implications. The focus of this review is urine output after ingestion of a drink; fluid excreted in urine counteracts rehydration. Also included are data on the restoration of plasma volume losses. Ingestion of large volumes of plain water will inhibit thirst and will also promote a diuretic response. If effective rehydration is to be maintained for some hours after fluid ingestion, drinks should contain moderately high levels of sodium (perhaps as much as 50-60 mmol/l) and possibly also some potassium to replace losses in the sweat. To surmount ongoing obligatory urine losses, the volume consumed should be greater than the volume of sweat lost. Palatability of drinks is important in stimulating intake and ensuring adequate volume replacement. Where opportunities allow, the electrolytes required may be ingested as solid food consumed with a drink. There are no special concerns for women related to changes in hormone levels associated with the menstrual cycle. Ingestion of carbohydrate-electrolyte drinks in the post-exercise period restores exercise capacity more effectively than plain water. The effects on performance of an uncorrected fluid deficit should persuade all athletes to attempt to remain fully hydrated at all times, and the aim should be to start each bout of exercise in a fluid replete state. This will only be achieved if a volume of fluid in excess of the sweat loss is ingested together with sufficient electrolytes. PMID:9298549

Modeling Ullage Dynamics of Tank Pressure Control Experiment during Jet Mixing in Microgravity

NASA Technical Reports Server (NTRS)

Kartuzova, O.; Kassemi, M.

2016-01-01

A CFD model for simulating the fluid dynamics of the jet induced mixing process is utilized in this paper to model the pressure control portion of the Tank Pressure Control Experiment (TPCE) in microgravity1. The Volume of Fluid (VOF) method is used for modeling the dynamics of the interface during mixing. The simulations were performed at a range of jet Weber numbers from non-penetrating to fully penetrating. Two different initial ullage positions were considered. The computational results for the jet-ullage interaction are compared with still images from the video of the experiment. A qualitative comparison shows that the CFD model was able to capture the main features of the interfacial dynamics, as well as the jet penetration of the ullage.

Well purge and sample apparatus and method

DOEpatents

Schalla, Ronald; Smith, Ronald M.; Hall, Stephen H.; Smart, John E.; Gustafson, Gregg S.

1995-01-01

The present invention specifically permits purging and/or sampling of a well but only removing, at most, about 25% of the fluid volume compared to conventional methods and, at a minimum, removing none of the fluid volume from the well. The invention is an isolation assembly with a packer, pump and exhaust, that is inserted into the well. The isolation assembly is designed so that only a volume of fluid between the outside diameter of the isolation assembly and the inside diameter of the well over a fluid column height from the bottom of the well to the top of the active portion (lower annulus) is removed. The packer is positioned above the active portion thereby sealing the well and preventing any mixing or contamination of inlet fluid with fluid above the packer. Ports in the wall of the isolation assembly permit purging and sampling of the lower annulus along the height of the active portion.

Well purge and sample apparatus and method

DOEpatents

Schalla, R.; Smith, R.M.; Hall, S.H.; Smart, J.E.; Gustafson, G.S.

1995-10-24

The present invention specifically permits purging and/or sampling of a well but only removing, at most, about 25% of the fluid volume compared to conventional methods and, at a minimum, removing none of the fluid volume from the well. The invention is an isolation assembly with a packer, pump and exhaust, that is inserted into the well. The isolation assembly is designed so that only a volume of fluid between the outside diameter of the isolation assembly and the inside diameter of the well over a fluid column height from the bottom of the well to the top of the active portion (lower annulus) is removed. The packer is positioned above the active portion thereby sealing the well and preventing any mixing or contamination of inlet fluid with fluid above the packer. Ports in the wall of the isolation assembly permit purging and sampling of the lower annulus along the height of the active portion. 8 figs.

Generalized Fluid System Simulation Program (GFSSP) - Version 6

NASA Technical Reports Server (NTRS)

Majumdar, Alok; LeClair, Andre; Moore, Ric; Schallhorn, Paul

2015-01-01

The Generalized Fluid System Simulation Program (GFSSP) is a finite-volume based general-purpose computer program for analyzing steady state and time-dependent flow rates, pressures, temperatures, and concentrations in a complex flow network. The program is capable of modeling real fluids with phase changes, compressibility, mixture thermodynamics, conjugate heat transfer between solid and fluid, fluid transients, pumps, compressors, flow control valves and external body forces such as gravity and centrifugal. The thermo-fluid system to be analyzed is discretized into nodes, branches, and conductors. The scalar properties such as pressure, temperature, and concentrations are calculated at nodes. Mass flow rates and heat transfer rates are computed in branches and conductors. The graphical user interface allows users to build their models using the 'point, drag, and click' method; the users can also run their models and post-process the results in the same environment. The integrated fluid library supplies thermodynamic and thermo-physical properties of 36 fluids, and 24 different resistance/source options are provided for modeling momentum sources or sinks in the branches. Users can introduce new physics, non-linear and time-dependent boundary conditions through user-subroutine.

Driving under the influence of cannabis: pitfalls, validation, and quality control of a UPLC-MS/MS method for the quantification of tetrahydrocannabinol in oral fluid collected with StatSure, Quantisal, or Certus collector.

PubMed

Wille, Sarah M R; Di Fazio, Vincent; Ramírez-Fernandez, Maria del Mar; Kummer, Natalie; Samyn, Nele

2013-02-01

"Driving under the influence of drugs" (DUID) has a large impact on the worldwide mortality risk. Therefore, DUID legislations based on impairment or analytical limits are adopted. Drug detection in oral fluid is of interest due to the ease of sampling during roadside controls. The prevalence of Δ9-tetrahydrocannabinol (THC) in seriously injured drivers ranges from 0.5% to 7.6% in Europe. For these reasons, the quantification of THC in oral fluid collected with 3 alternative on-site collectors is presented and discussed in this publication. An ultra-performance liquid chromatography-mass spectrometric quantification method for THC in oral fluid samples collected with the StatSure (Diagnostic Systems), Quantisal (Immunalysis), and Certus (Concateno) devices was validated according to the international guidelines. Small sample volumes of 100-200 μL were extracted using hexane. Special attention was paid to factors such as matrix effects, THC adsorption onto the collector, and stability in the collection fluid. A relatively high-throughput analysis was developed and validated according to ISO 17025 requirements. Although the effects of the matrix on the quantification could be minimized using a deuterated internal standard, and stability was acceptable according the validation data, adsorption of THC onto the collectors was a problem. For the StatSure device, THC was totally recovered from the collector pad after storage for 24 hours at room temperature or 7 days at 4°C. A loss of 15%-25% was observed for the Quantisal collector, whereas the recovery from the Certus device was irreproducible (relative standard deviation, 44%-85%) and low (29%-80%). During the roadside setting, a practical problem arose: small volumes of oral fluid (eg, 300 μL) were collected. However, THC was easily detected and concentrations ranged from 8 to 922 ng/mL in neat oral fluid. A relatively high-throughput analysis (40 samples in 4 hours) adapted for routine DUID analysis was developed and validated for THC quantification in oral fluid samples collected from drivers under the influence of cannabis.

High tidal volume ventilation induces NOS2 and impairs cAMP- dependent air space fluid clearance.

PubMed

Frank, James A; Pittet, Jean-Francois; Lee, Hyon; Godzich, Micaela; Matthay, Michael A

2003-05-01

Tidal volume reduction during mechanical ventilation reduces mortality in patients with acute lung injury and the acute respiratory distress syndrome. To determine the mechanisms underlying the protective effect of low tidal volume ventilation, we studied the time course and reversibility of ventilator-induced changes in permeability and distal air space edema fluid clearance in a rat model of ventilator-induced lung injury. Anesthetized rats were ventilated with a high tidal volume (30 ml/kg) or with a high tidal volume followed by ventilation with a low tidal volume of 6 ml/kg. Endothelial and epithelial protein permeability were significantly increased after high tidal volume ventilation but returned to baseline levels when tidal volume was reduced. The basal distal air space fluid clearance (AFC) rate decreased by 43% (P < 0.05) after 1 h of high tidal volume but returned to the preventilation rate 2 h after tidal volume was reduced. Not all of the effects of high tidal volume ventilation were reversible. The cAMP-dependent AFC rate after 1 h of 30 ml/kg ventilation was significantly reduced and was not restored when tidal volume was reduced. High tidal volume ventilation also increased lung inducible nitric oxide synthase (NOS2) expression and air space total nitrite at 3 h. Inhibition of NOS2 activity preserved cAMP-dependent AFC. Because air space edema fluid inactivates surfactant and reduces ventilated lung volume, the reduction of cAMP-dependent AFC by reactive nitrogen species may be an important mechanism of clinical ventilator-associated lung injury.

Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration.

PubMed

Evans, Gethin H; James, Lewis J; Shirreffs, Susan M; Maughan, Ronald J

2017-04-01

Hypohydration, or a body water deficit, is a common occurrence in athletes and recreational exercisers following the completion of an exercise session. For those who will undertake a further exercise session that day, it is important to replace water losses to avoid beginning the next exercise session hypohydrated and the potential detrimental effects on performance that this may lead to. The aim of this review is to provide an overview of the research related to factors that may affect postexercise rehydration. Research in this area has focused on the volume of fluid to be ingested, the rate of fluid ingestion, and fluid composition. Volume replacement during recovery should exceed that lost during exercise to allow for ongoing water loss; however, ingestion of large volumes of plain water results in a prompt diuresis, effectively preventing longer-term maintenance of water balance. Addition of sodium to a rehydration solution is beneficial for maintenance of fluid balance due to its effect on extracellular fluid osmolality and volume. The addition of macronutrients such as carbohydrate and protein can promote maintenance of hydration by influencing absorption and distribution of ingested water, which in turn effects extracellular fluid osmolality and volume. Alcohol is commonly consumed in the postexercise period and may influence postexercise rehydration, as will the coingestion of food. Future research in this area should focus on providing information related to optimal rates of fluid ingestion, advisable solutions to ingest during different duration recovery periods, and confirmation of mechanistic explanations for the observations outlined. Copyright © 2017 the American Physiological Society.

40 CFR 146.69 - Reporting requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... pursuant to § 146.67(f) and the response taken; (4) The total volume of fluid injected; (5) Any change in the annular fluid volume; (6) The physical, chemical and other relevant characteristics of injected...

Does adenosine triphosphate released into voided urodynamic fluid contribute to urgency signaling in women with bladder dysfunction?

PubMed

Cheng, Ying; Mansfield, Kylie J; Allen, Wendy; Walsh, Colin A; Burcher, Elizabeth; Moore, Kate H

2010-03-01

Adenosine triphosphate released from urothelium during stretch stimulates afferent nerves and conveys information on bladder fullness. We measured adenosine triphosphate released during cystometric bladder filling in women with idiopathic detrusor overactivity and stress incontinence (controls), and assessed whether the level of released adenosine triphosphate is related to cystometric parameters. Routine cystometry was done in 51 controls and 48 women with detrusor overactivity who were 28 to 87 years old. Voided urodynamic fluid was collected and stored at -30 C. Adenosine triphosphate was measured by a bioluminescence assay. Adenosine triphosphate levels were similar in voided urodynamic fluid of controls and patients with detrusor overactivity (p = 0.79). A significant inverse correlation was seen between adenosine triphosphate and maximal cystometric capacity in controls (p = 0.013), and between voided volume and adenosine triphosphate in controls (p = 0.015) and detrusor overactivity cases (p = 0.019). A significant correlation between first desire to void and adenosine triphosphate was also noted in detrusor overactivity cases (p = 0.033) but not in controls (p = 0.58). No correlation was seen between adenosine triphosphate and detrusor pressure during filling or voiding. Adenosine triphosphate measurement in voided urodynamic fluid is a novel approach to understanding signals that may contribute to the urgency sensation (a sudden compelling desire to pass urine). The inverse correlation between adenosine triphosphate in voided urodynamic fluid and first desire to void suggests that adenosine triphosphate has a role in modulating the early filling sensation in patients with detrusor overactivity. 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Fault geometry and fluid-rock reaction: Combined controls on mineralization in the Xinli gold deposit, Jiaodong Peninsula, China

NASA Astrophysics Data System (ADS)

Yang, Lin; Zhao, Rui; Wang, Qingfei; Liu, Xuefei; Carranza, Emmanuel John M.

2018-06-01

The structures and fluid-rock reaction in the Xinli gold deposit, Jiaodong Peninsula, were investigated to further understand their combined controls on the development of permeability associated with ore-forming fluid migration. Orebodies in this deposit are hosted by the moderately SE-to S-dipping Sanshandao-Cangshang fault (SCF). Variations in both dip direction and dip angle along the SCF plane produced fault bends, which controlled the fluid accumulation and ore-shoot formation. Gold mineralizations occurred in early gold-quartz-pyrite and late gold-quartz-polymetallic sulphide stages following pervasive sericitization and silicification alterations. Theoretical calculation indicates that sericitization caused 8-57% volume decrease resulting in the development/enlargement of voids, further increase of grain-scale permeability, and resultant precipitation of the early gold-quartz-pyrite pods, which destroyed permeability. The rock softening produced by alterations promoted activities of SCF secondary faults and formation of new fractures, which rebuilt the permeability and controlled the late gold-quartz-polymetallic sulfide veins. Quantitative studies on permeability distributions show that the southwestern and northeastern bend areas with similar alteration and mineralization have persistent and anti-persistent permeability networks, respectively. These were likely caused by different processes of rebuilding permeability due to different stress states resulting from changes in fault geometry.

Goal-directed fluid therapy may improve hemodynamic stability in parturient women under combined spinal epidural anesthesia for cesarean section and newborn well-being.

PubMed

Xiao, Wei; Duan, Qingfang; Zhao, Lei; Chi, Xinzuo; Wang, Fengying; Ma, Daqing; Wang, Tianlong

2015-10-01

To investigate whether goal-directed fluid therapy (GDFT) with the LiDCOrapid system can reduce the incidence of maternal hypotension and improve neonatal outcome. One hundred healthy term parturient women scheduled for elective cesarean section were recruited. After loading with 10 mL/kg Lactated Ringer's solution, parturient women were randomized to the GDFT and control group. In the GDFT group, individualized fluid therapy was implemented to optimize stroke volume, guided by the LiDCOrapid system. The control group received routine fluid therapy. Primary endpoints included onset of maternal hypotension, and vasopressor doses prior to delivery. The secondary endpoints included umbilical blood gas abnormalities and neonatal adverse events. Incidence of hypotension and mean phenylephrine dose administered prior to delivery were significantly higher in the control group than in the GDFT group (P < 0.01). There was no difference in Apgar score between the two groups. In the control group, mean umbilical artery and vein blood pH were significantly lower, corresponding to significantly higher incidences of neonatal hypercapnia and hypoxemia, compared with the GDFT group (P < 0.05). LiDCOrapid -guided GDFT may provide benefit to healthy parturient women and their newborns. © 2015 Japan Society of Obstetrics and Gynecology.

30 CFR 250.456 - What safe practices must the drilling fluid program follow?

Code of Federal Regulations, 2012 CFR

2012-07-01

... circulate a volume of drilling fluid equal to the annular volume with the drill pipe just off-bottom. You... volume needed to fill the hole. Both sets of numbers must be posted near the driller's station. You must... industry-accepted practices and include density, viscosity, and gel strength; hydrogenion concentration...

30 CFR 250.456 - What safe practices must the drilling fluid program follow?

Code of Federal Regulations, 2014 CFR

2014-07-01

... circulate a volume of drilling fluid equal to the annular volume with the drill pipe just off-bottom. You... volume needed to fill the hole. Both sets of numbers must be posted near the driller's station. You must... industry-accepted practices and include density, viscosity, and gel strength; hydrogenion concentration...

30 CFR 250.456 - What safe practices must the drilling fluid program follow?

Code of Federal Regulations, 2013 CFR

2013-07-01

... circulate a volume of drilling fluid equal to the annular volume with the drill pipe just off-bottom. You... volume needed to fill the hole. Both sets of numbers must be posted near the driller's station. You must... industry-accepted practices and include density, viscosity, and gel strength; hydrogenion concentration...

Unsteady force estimation using a Lagrangian drift-volume approach

NASA Astrophysics Data System (ADS)

McPhaden, Cameron J.; Rival, David E.

2018-04-01

A novel Lagrangian force estimation technique for unsteady fluid flows has been developed, using the concept of a Darwinian drift volume to measure unsteady forces on accelerating bodies. The construct of added mass in viscous flows, calculated from a series of drift volumes, is used to calculate the reaction force on an accelerating circular flat plate, containing highly-separated, vortical flow. The net displacement of fluid contained within the drift volumes is, through Darwin's drift-volume added-mass proposition, equal to the added mass of the plate and provides the reaction force of the fluid on the body. The resultant unsteady force estimates from the proposed technique are shown to align with the measured drag force associated with a rapid acceleration. The critical aspects of understanding unsteady flows, relating to peak and time-resolved forces, often lie within the acceleration phase of the motions, which are well-captured by the drift-volume approach. Therefore, this Lagrangian added-mass estimation technique opens the door to fluid-dynamic analyses in areas that, until now, were inaccessible by conventional means.

MRI Assessment of Superior Temporal Gyrus in Williams Syndrome

PubMed Central

Sampaio, Adriana; Sousa, Nuno; Férnandez, Montse; Vasconcelos, Cristiana; Shenton, Martha E.; Gonçalves, Óscar F.

2009-01-01

Objective To evaluate volumes and asymmetry of superior temporal gyrus (STG) and correlate these measures with a neurocognitive evaluation of verbal performance in Williams syndrome (WS) and in a typically developing age-matched and sex-matched group. Background Despite initial claims of language strength in WS, recent studies suggest delayed language milestones. The STG is implicated in linguistic processing and is a highly lateralized brain region. Method Here, we examined STG volumes and asymmetry of STG in WS patients and in age-matched controls. We also correlated volume of STG with a subset of verbal measures. Magnetic resonance imaging scans were obtained on a GE 1.5-T magnet with 1.5-mm contiguous slices, and were used to measure whole gray matter, white matter, and cerebrospinal fluid volumes, and also STG volume. Results Results revealed significantly reduced intracranial volume in WS patients, compared with controls. Right and left STG were also significantly smaller in WS patients. In addition, compared with normal controls, a lack of normal left >right STG asymmetry was evident in WS. Also of note was the finding that, in contrast to controls, WS patients did not reveal a positive correlation between verbal intelligence quotient and left STG volume, which further suggests a disruption in this region of the brain. Conclusions In conclusion, atypical patterns of asymmetry and reduced STG volume in WS were observed, which may, in part, contribute to some of the linguistic impairments found in this cohort of WS patients. PMID:18797257

Bioimpedance Measurement of Segmental Fluid Volumes and Hemodynamics

NASA Technical Reports Server (NTRS)

Montgomery, Leslie D.; Wu, Yi-Chang; Ku, Yu-Tsuan E.; Gerth, Wayne A.; DeVincenzi, D. (Technical Monitor)

2000-01-01

Bioimpedance has become a useful tool to measure changes in body fluid compartment volumes. An Electrical Impedance Spectroscopic (EIS) system is described that extends the capabilities of conventional fixed frequency impedance plethysmographic (IPG) methods to allow examination of the redistribution of fluids between the intracellular and extracellular compartments of body segments. The combination of EIS and IPG techniques was evaluated in the human calf, thigh, and torso segments of eight healthy men during 90 minutes of six degree head-down tilt (HDT). After 90 minutes HDT the calf and thigh segments significantly (P < 0.05) lost conductive volume (eight and four percent, respectively) while the torso significantly (P < 0.05) gained volume (approximately three percent). Hemodynamic responses calculated from pulsatile IPG data also showed a segmental pattern consistent with vascular fluid loss from the lower extremities and vascular engorgement in the torso. Lumped-parameter equivalent circuit analyses of EIS data for the calf and thigh indicated that the overall volume decreases in these segments arose from reduced extracellular volume that was not completely balanced by increased intracellular volume. The combined use of IPG and EIS techniques enables noninvasive tracking of multi-segment volumetric and hemodynamic responses to environmental and physiological stresses.

Peripheral i.v. analysis (PIVA) of venous waveforms for volume assessment in patients undergoing haemodialysis.

PubMed

Hocking, K M; Alvis, B D; Baudenbacher, F; Boyer, R; Brophy, C M; Beer, I; Eagle, S

2017-12-01

The assessment of intravascular volume status remains a challenge for clinicians. Peripheral i.v. analysis (PIVA) is a method for analysing the peripheral venous waveform that has been used to monitor volume status. We present a proof-of-concept study for evaluating the efficacy of PIVA in detecting changes in fluid volume. We enrolled 37 hospitalized patients undergoing haemodialysis (HD) as a controlled model for intravascular volume loss. Respiratory rate (F0) and pulse rate (F1) frequencies were measured. PIVA signal was obtained by fast Fourier analysis of the venous waveform followed by weighing the magnitude of the amplitude of the pulse rate frequency. PIVA was compared with peripheral venous pressure and standard monitoring of vital signs. Regression analysis showed a linear correlation between volume loss and change in the PIVA signal (R2=0.77). Receiver operator curves demonstrated that the PIVA signal showed an area under the curve of 0.89 for detection of 20 ml kg-1 change in volume. There was no correlation between volume loss and peripheral venous pressure, blood pressure or pulse rate. PIVA-derived pulse rate and respiratory rate were consistent with similar numbers derived from the bio-impedance and electrical signals from the electrocardiogram. PIVA is a minimally invasive, novel modality for detecting changes in fluid volume status, respiratory rate and pulse rate in spontaneously breathing patients with peripheral i.v. cannulas. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Design study of RL10 derivatives. Volume 3, part 1: Preliminary interface control document. [development of baseline engines for space tug vehicles

NASA Technical Reports Server (NTRS)

Adams, A.

1973-01-01

The Interface Control Document contains engine information necessary for installation of the baseline RL10 Derivative engines in the Space Tug vehicle. The ICD presents a description of the baseline engines and their operating characteristics, mass and load characteristics, and environmental criteria. The document defines the engine/vehicle mechanical, electrical, fluid and pneumatic interface requirements.

Journal of Special Operations Medicine. Volume 7, Edition 1, Winter 2007. Training Supplement: USSOCOM Medic Certification Program

DTIC Science & Technology

2007-01-01

Complicated intra-abdominal infections Complicated skin infections Pneumonia Complicated UTI , including pyelonephritis Acute pelvic infections Drug of...nitroimidazole derivatives. Pregnancy (first trimester in patients with Trichomoniasis). Administer with caution to patients with CNS diseases. Use with caution...under 12 years Dehydration Use with caution in pregnancy . Dosage: Patient in shock, bleeding not controlled: hold fluid and control bleeding. Patient

CT and MRI assessment of symptomatic organized pancreatic fluid collections and pancreatic duct disruption: an interreader variability study using the revised Atlanta classification 2012.

PubMed

Kamal, Ayesha; Singh, Vikesh K; Akshintala, Venkata S; Kawamoto, Satomi; Tsai, Salina; Haider, Maera; Fishman, Elliot K; Kamel, Ihab R; Zaheer, Atif

2015-08-01

Compare CT and MRI for fluid/debris component estimate and pancreatic duct (PD) communication with organized pancreatic fluid collections in acute pancreatitis. Evaluate fat density globules on CT as marker for debris. 29 Patients with 46 collections with CECT and MRI performed ≥4 weeks of symptom onset assessed for necrotizing pancreatitis, estimated percentage of fluid volume and PD involvement by two radiologists on separate occasions. T2WI used as standard for estimated percentage of fluid volume. Presence of fat globules and fluid attenuation on CT was recorded. Spearman rank correlation and kappa statistics were used to assess the correlation between imaging techniques and interreader agreement, respectively. Necrotizing pancreatitis seen on CT in 27 (93%, κ 0.119) vs. 20 (69%, κ 0.748) patients on MRI. CT identified 42 WON and 4 pseudocysts vs. 34 WON, and 12 pseudocysts on MRI. Higher interreader agreement for percentage fluid volume on MRI (κ = 0.55) vs. CT (κ = 0.196). Accuracy of CT in evaluation of percentage fluid volume was 65% using T2WI MRI used as standard. Fat globules identified on CT in 13(65%) out of 20 collections containing <75% fluid vs. 4(15%) out of 26 collections containing >75% fluid (p = 0.0001). PD involvement confidently excluded on CT in 68% collections vs. 93% on MRI. MRI demonstrates higher reproducibility for fluid to debris component estimation. Fat globules on CT were frequently seen in organized pancreatic fluid collections with large amount of debris. PD disruption more confidently excluded on MRI. This information may be helpful for pre-procedure planning.

Numerical analysis and experiment research on fluid orbital performance of vane type propellant management device

NASA Astrophysics Data System (ADS)

Hu, Q.; Li, Y.; Pan, H. L.; Liu, J. T.; Zhuang, B. T.

2015-01-01

Vane type propellant management device (PMD) is one of the key components of the vane-type surface tension tank (STT), and its fluid orbital performance directly determines the STT's success or failure. In present paper, numerical analysis and microgravity experiment study on fluid orbital performance of a vane type PMD were carried out. By using two-phase flow model of volume of fluid (VOF), fluid flow characteristics in the tank with the vane type PMD were numerically calculated, and the rules of fluid transfer and distribution were gotten. A abbreviate model test system of the vane type PMD is established and microgravity drop tower tests were performed, then fluid management and transmission rules of the vane type PMD were obtained under microgravity environment. The analysis and tests results show that the vane type PMD has good and initiative fluid orbital management ability and meets the demands of fluid orbital extrusion in the vane type STT. The results offer valuable guidance for the design and optimization of the new generation of vane type PMD, and also provide a new approach for fluid management and control in space environment.

The value of the 4-day headdown bedrest model for screening countermeasures

NASA Technical Reports Server (NTRS)

Vernikos, J.; Keil, L.; Ertl, A. C.; Wade, C. E.; Greenleaf, J. E.; Ohara, D.; Ludwig, D.

1992-01-01

In order to evaluate the benefits of periodic exposure to the +G(z) vector as a countermeasure to the physiological responses to minus 6 degree head down bedrest (HDT), we considered a two-tiered approach: (a) to use 4 days HDT as a quick and inexpensive means of screening countermeasures, (b) to use a 60 day HDT to validate the most promising candidates. The approach and results of a 4 day study are described here. Methods: Nine males were admitted to our Human Research Facility for one ambulatory control day followed by 4 days HDT and were released on the next day after completion of a peak oxygen consumption test (VO(sub 2 peak)). A battery of tests was selected and standardized to evaluate the known early effects of HDT on plasma volume, early bone markers, orthostatic tolerance, physical performance, and fluid and electrolytes and their hormone regulation. Fluid sodium (Na) and potassium (K) intake and output in the urine were monitored throughout. Plasma volume was determined with a modified Evans Blue method and orthostatic tolerance with a 60 degree head-up tilt test for 30 minutes - both of which were determined on the ambulatory control day and on day 4 of HDT. Immediately after completion of the tilt test subjects were returned to the minus 6 degree position until the next morning when a VO(sub 2 peak) (horizontal ergometer) was done. This was compared to a similar control test determined on 2 separate occasions before subject admission. Results: Four hours after going HDT produced significant decreases (p less than 0.05) in the circulating concentration of fluid and electrolyte regulating hormones. Plasma volume, orthostatic tolerance and VO(sub 2 peak) changed significantly after 4 days HDT. There was also the expected natriuresis on day 1 of HDT but no significant diuresis. The consistency of the pre-bedrest VO(sub 2 peak) tilt tests and plasma volumes was remarkable. Conclusions: The 4 day HDT model seems highly promising for screening a variety of countermeasures alone and in combination before validating their benefits in extended bedrest or flight experiments.

Influence of mechanical rock properties and fracture healing rate on crustal fluid flow dynamics

NASA Astrophysics Data System (ADS)

Sachau, Till; Bons, Paul; Gomez-Rivas, Enrique; Koehn, Daniel; de Riese, Tamara

2016-04-01

Fluid flow in the Earth's crust is very slow over extended periods of time, during which it occurs within the connected pore space of rocks. If the fluid production rate exceeds a certain threshold, matrix permeability alone is insufficient to drain the fluid volume and fluid pressure builds up, thereby reducing the effective stress supported by the rock matrix. Hydraulic fractures form once the effective pressure exceeds the tensile strength of the rock matrix and act subsequently as highly effective fluid conduits. Once local fluid pressure is sufficiently low again, flow ceases and fractures begin to heal. Since fluid flow is controlled by the alternation of fracture permeability and matrix permeability, the flow rate in the system is strongly discontinuous and occurs in intermittent pulses. Resulting hydraulic fracture networks are largely self-organized: opening and subsequent healing of hydraulic fractures depends on the local fluid pressure and on the time-span between fluid pulses. We simulate this process with a computer model and describe the resulting dynamics statistically. Special interest is given to a) the spatially and temporally discontinuous formation and closure of fractures and fracture networks and b) the total flow rate over time. The computer model consists of a crustal-scale dual-porosity setup. Control parameters are the pressure- and time-dependent fracture healing rate, and the strength and the permeability of the intact rock. Statistical analysis involves determination of the multifractal properties and of the power spectral density of the temporal development of the total drainage rate and hydraulic fractures. References Bons, P. D. (2001). The formation of large quartz veins by rapid ascent of fluids in mobile hydrofractures. Tectonophysics, 336, 1-17. Miller, S. a., & Nur, A. (2000). Permeability as a toggle switch in fluid-controlled crustal processes. Earth and Planetary Science Letters, 183(1-2), 133-146. Sachau, T., Bons, P. D., & Gomez-Rivas, E. (2015). Transport efficiency and dynamics of hydraulic fracture networks. Frontiers in Physics, 3.

A modeling technique for STOVL ejector and volume dynamics

NASA Technical Reports Server (NTRS)

Drummond, C. K.; Barankiewicz, W. S.

1990-01-01

New models for thrust augmenting ejector performance prediction and feeder duct dynamic analysis are presented and applied to a proposed Short Take Off and Vertical Landing (STOVL) aircraft configuration. Central to the analysis is the nontraditional treatment of the time-dependent volume integrals in the otherwise conventional control-volume approach. In the case of the thrust augmenting ejector, the analysis required a new relationship for transfer of kinetic energy from the primary flow to the secondary flow. Extraction of the required empirical corrections from current steady-state experimental data is discussed; a possible approach for modeling insight through Computational Fluid Dynamics (CFD) is presented.

A fluid secretion pathway unmasked by acinar-specific Tmem16A gene ablation in the adult mouse salivary gland

PubMed Central

Catalán, Marcelo A.; Kondo, Yusuke; Peña-Munzenmayer, Gaspar; Jaramillo, Yasna; Liu, Frances; Choi, Sooji; Crandall, Edward; Borok, Zea; Flodby, Per; Shull, Gary E.; Melvin, James E.

2015-01-01

Activation of an apical Ca2+-activated Cl− channel (CaCC) triggers the secretion of saliva. It was previously demonstrated that CaCC-mediated Cl− current and Cl− efflux are absent in the acinar cells of systemic Tmem16A (Tmem16A Cl− channel) null mice, but salivation was not assessed in fully developed glands because Tmem16A null mice die within a few days after birth. To test the role of Tmem16A in adult salivary glands, we generated conditional knockout mice lacking Tmem16A in acinar cells (Tmem16A−/−). Ca2+-dependent salivation was abolished in Tmem16A−/− mice, demonstrating that Tmem16A is obligatory for Ca2+-mediated fluid secretion. However, the amount of saliva secreted by Tmem16A−/− mice in response to the β-adrenergic receptor agonist isoproterenol (IPR) was comparable to that seen in controls, indicating that Tmem16A does not significantly contribute to cAMP-induced secretion. Furthermore, IPR-stimulated secretion was unaffected in mice lacking Cftr (Cftr∆F508/∆F508) or ClC-2 (Clcn2−/−) Cl− channels. The time course for activation of IPR-stimulated fluid secretion closely correlated with that of the IPR-induced cell volume increase, suggesting that acinar swelling may activate a volume-sensitive Cl− channel. Indeed, Cl− channel blockers abolished fluid secretion, indicating that Cl− channel activity is critical for IPR-stimulated secretion. These data suggest that β-adrenergic–induced, cAMP-dependent fluid secretion involves a volume-regulated anion channel. In summary, our results using acinar-specific Tmem16A−/− mice identify Tmem16A as the Cl− channel essential for muscarinic, Ca2+-dependent fluid secretion in adult mouse salivary glands. PMID:25646474

Liberal perioperative fluid administration is an independent risk factor for morbidity and is associated with longer hospital stay after rectal cancer surgery.

PubMed

Boland, M R; Reynolds, I; McCawley, N; Galvin, E; El-Masry, S; Deasy, J; McNamara, D A

2017-02-01

INTRODUCTION Recent studies have advocated the use of perioperative fluid restriction in patients undergoing major abdominal surgery as part of an enhanced recovery protocol. Series reported to date include a heterogenous group of high- and low-risk procedures but few studies have focused on rectal cancer surgery alone. The aim of this study was to assess the effects of perioperative fluid volumes on outcomes in patients undergoing elective rectal cancer resection. METHODS A prospectively maintained database of patients with rectal cancer who underwent elective surgery over a 2-year period was reviewed. Total volume of fluid received intraoperatively was calculated, as well as blood products required in the perioperative period. The primary outcome was postoperative morbidity (Clavien-Dindo grade I-IV) and the secondary outcomes were length of stay and major morbidity (Clavien-Dindo grade III-IV). RESULTS Over a 2-year period (2012-2013), 120 patients underwent elective surgery with curative intent for rectal cancer. Median total intraoperative fluid volume received was 3680ml (range 1200-9670ml); 65/120 (54.1%) had any complications, with 20/120 (16.6%) classified as major (Clavien-Dindo grade III-IV). Intraoperative volume >3500ml was an independent risk factor for the development of postoperative all-cause morbidity (P=0.02) and was associated with major morbidity (P=0.09). Intraoperative fluid volumes also correlated with length of hospital stay (Pearson's correlation coefficient 0.33; P<0.01). CONCLUSIONS Intraoperative fluid infusion volumes in excess of 3500ml are associated with increased morbidity and length of stay in patients undergoing elective surgery for rectal cancer.

Electrical capacitance volume tomography (ECVT) applied to bubbling fluid beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, J., Mei, J.

2012-01-01

These presentation visuals illustrate the apparatus and method for applying Electrical Capacitance Volume Tomography (ECVT) to bubbling fluid beds to their solid fraction and bubble properties. Results are compared to estimated values.

The effect of fluid overload on sleep apnoea severity in haemodialysis patients.

PubMed

Lyons, Owen D; Inami, Toru; Perger, Elisa; Yadollahi, Azadeh; Chan, Christopher T; Bradley, T Douglas

2017-04-01

As in heart failure, obstructive and central sleep apnoea (OSA and CSA, respectively) are common in end-stage renal disease. Fluid overload characterises end-stage renal disease and heart failure, and in heart failure plays a role in the pathogenesis of OSA and CSA. We postulated that in end-stage renal disease patients, those with sleep apnoea would have greater fluid volume overload than those without.End-stage renal disease patients on thrice-weekly haemodialysis underwent overnight polysomnography on a nondialysis day to determine their apnoea-hypopnoea index (AHI). Extracellular fluid volume of the total body, neck, thorax and right leg were measured using bioelectrical impedance.28 patients had an AHI ≥15 (sleep apnoea group; OSA:CSA 21:7) and 12 had an AHI <15 (no sleep apnoea group). Total body extracellular fluid volume was 2.6 L greater in the sleep apnoea group than in the no sleep apnoea group (p=0.006). Neck, thorax, and leg fluid volumes were also greater in the sleep apnoea than the no sleep apnoea group (p<0.05), despite no difference in body mass index (p=0.165).These findings support a role for fluid overload in the pathogenesis of both OSA and CSA in end-stage renal disease. Copyright ©ERS 2017.

On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

NASA Astrophysics Data System (ADS)

Kenjeres, S.

2016-09-01

In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and LIF) techniques to provide fundamental insights into the complex phenomena of interactions between imposed (or induced) electromagnetic fields and underlying fluid flow. Our analysis covers an extensive range of working fluids, i.e. weakly- and highly-electrically-conductive, as well as magnetized fluids. These interactions are defined through the presence of different types of body forces acting per volume of fluid. A fully closed system of governing equations containing an extended set of the Navier-Stokes and a simplified set of the Maxwell equations is presented. The four characteristic examples are selected: the electromagnetic control of self-sustained jet oscillations, the electromagnetic enhancement of heat transfer in thermal convection, the wake interactions behind magnetic obstacles and finally, the thermo-magnetic convection in differentially heated cubical enclosure. The comparative assessment between experimental and numerical results is presented. It is concluded that generally good agreement between simulations and experiments is obtained for all cases considered, proving the concept of electromagnetic modulation, which can be used in numerous technological applications.

A review on optical actuators for microfluidic systems

NASA Astrophysics Data System (ADS)

Yang, Tie; Chen, Yue; Minzioni, Paolo

2017-12-01

During the last few decades microfluidic systems have become more and more popular and their relevance in different fields is continually growing. In fact, the use of microchannels allows a significant reduction of the required sample-volume and opens the way to a completely new set of possible investigations, including the study of the properties of cells, the development of new cells’ separation techniques and the analysis of single-cell proteins. One of the main differences between microscopic and macroscopic systems is obviously dictated by the need for suitable actuation mechanisms, which should allow precise control of microscopic fluid volumes and of micro-samples inside the fluid. Even if both syringe-pump and pneumatic-pump technologies significantly evolved and they currently enable sub-μL samples control, completely new approaches were recently developed for the manipulation of samples inside the microchannel. This review is dedicated to describing different kinds of optical actuators that can be applied in microfluidic systems for sample manipulation as well as for pumping. The basic principles underlying the optical actuation mechanisms will be described first, and then several experimental demonstrations will be reviewed and compared.

[Expressions of EMMPRIN and its ligand CyPA in gingival crevicular fluid of chronic periodontitis patients].

PubMed

He, Yan-ping; Xie, Ming; Jiao, Ting

2016-02-01

To detect the expressions of EMMPRIN and its ligand CyPA in gingival crevicular fluid (GCF) of chronic periodontitis (CP) patients and explore their possible relation to the status of periodontal inflammation. GCF of CP patients (group CP) and periodontitis-free patients with intact dentition (the control group) were collected and assayed for EMMPRIN and CyPA expressions by ELISA. The clinical periodontal status of these patients were examined. Statistical analysis was performed by use of SPSS 17.0 software package. Spearman's correlation analysis was utilized to determine the relationships between the expressions of EMMPRIN and CyPA in GCF and the clinical parameters. In addition, analysis of variance (ANOVA) was used for comparing the difference between group CP and the control group. In group CP, GCF volume was positively correlated with EMMPRIN total amount, CyPA total amount and some clinical periodontal indexes (GI,SBI,AL). EMMPRIN total amount was positively correlated with GCF volume, CyPA total amount and some of clinical periodontal indexes (GI,SBI,AL), but it was negatively correlated with smoking status (P<0.05). Moreover, CyPA total amount was positively correlated with GCF volume, EMMPRIN total amount and some of clinical periodontal indexes (GI,SBI,AL). In the control group,there were significant positive correlations among GCF volume, EMMPRIN total amount and CyPA total amount. The difference of GCF, EMMPRIN and CyPA between the 2 groups were statistically significant (P<0.05). EMMPRIN and its ligand CyPA in GCF of periodontitis-free patients with intact dentition and CP patients were all detected. As the progress of periodontal inflammation, GCF secretion increases, as well as the expressions of EMMPRIN and CyPA in GCF.

Fluid Status in Peritoneal Dialysis Patients: The European Body Composition Monitoring (EuroBCM) Study Cohort

PubMed Central

Van Biesen, Wim; Williams, John D.; Covic, Adrian C.; Fan, Stanley; Claes, Kathleen; Lichodziejewska-Niemierko, Monika; Verger, Christian; Steiger, Jurg; Schoder, Volker; Wabel, Peter; Gauly, Adelheid; Himmele, Rainer

2011-01-01

Background Euvolemia is an important adequacy parameter in peritoneal dialysis (PD) patients. However, accurate tools to evaluate volume status in clinical practice and data on volume status in PD patients as compared to healthy population, and the associated factors, have not been available so far. Methods We used a bio-impedance spectroscopy device, the Body Composition Monitor (BCM) to assess volume status in a cross-sectional cohort of prevalent PD patients in different European countries. The results were compared to an age and gender matched healthy population. Results Only 40% out of 639 patients from 28 centres in 6 countries were normovolemic. Severe fluid overload was present in 25.2%. There was a wide scatter in the relation between blood pressure and volume status. In a multivariate analysis in the subgroup of patients from countries with unrestricted availability of all PD modalities and fluid types, older age, male gender, lower serum albumin, lower BMI, diabetes, higher systolic blood pressure, and use of at least one exchange per day with the highest hypertonic glucose were associated with higher relative tissue hydration. Neither urinary output nor ultrafiltration, PD fluid type or PD modality were retained in the model (total R2 of the model = 0.57). Conclusions The EuroBCM study demonstrates some interesting issues regarding volume status in PD. As in HD patients, hypervolemia is a frequent condition in PD patients and blood pressure can be a misleading clinical tool to evaluate volume status. To monitor fluid balance, not only fluid output but also dietary input should be considered. Close monitoring of volume status, a correct dialysis prescription adapted to the needs of the patient and dietary measures seem to be warranted to avoid hypervolemia. PMID:21390320

Flow rate measurement in a volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galvez, Cristhian

A system for measuring flow rate within a volume includes one or more transmission devices that transmit one or more signals through fluid contained within the volume. The volume may be bounded, at least in part, by an outer structure and by an object at least partially contained within the outer structure. A transmission device located at a first location of the outer structure transmits a first signal to a second location of the outer structure. A second signal is transmitted through the fluid from the second location to a third location of the outer structure. The flow rate ofmore » the fluid within the volume may be determined based, at least in part, on the time of flight of both the first signal and the second signal.« less

A liquid-delivery device that provides precise reward control for neurophysiological and behavioral experiments.

PubMed

Mitz, Andrew R

2005-10-15

Behavioral neurophysiology and other kinds of behavioral research often involve the delivery of liquid rewards to experimental subjects performing some kind of operant task. Available systems use gravity or pumps to deliver these fluids, but such methods are poorly suited to moment-to-moment control of the volume, timing, and type of fluid delivered. The design described here overcomes these limitations using an electronic control unit, a pressurized reservoir unit, and an electronically controlled solenoid. The control unit monitors reservoir pressure and provides precisely timed solenoid activation signals. It also stores calibration tables and does on-the-fly interpolation to support computer-controlled delivery calibrated directly in milliliters. The reservoir provides pressurized liquid to a solenoid mounted near the subject. Multiple solenoids, each supplied by a separate reservoir unit and control unit, can be stacked in close proximity to allow instantaneous selection of which liquid reward is delivered. The precision of droplet delivery was verified by weighing discharged droplets on a commercial analytical balance.

Vascular Uptake of Six Rehydration Drinks at Rest and Exercise

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Geelen, G.; Jackson, C. G. R.; Saumet, J.-L.; Juhos, L. T.; Keil, L. C.; Fegan-Meyer, D.; Dearborn, A.; Hinghofer-Szalkay, H.; Whittam, J. H.

1996-01-01

A report presents data on the effectiveness of each of six rehydration fluids in restoring total body water and plasma volume in human subjects during rest and exercise. One of the six fluids was water sweetened with aspartame: the others were water containing various amounts of sodium chloride and/or sodium citrate, plus various amounts of aspartame and/or other carbohydrates. In one experiment, five men who had previously dehydrated themselves for 24 hours drank one of the rehydration fluids, then sat for 70 minutes. Pretest plasma volumes were measured and changes in plasma volumes were calculated. This procedure was repeated at weekly intervals until all six rehydration fluids had been tested. Another similar experiment involved four men who exercised on a cycle ergometer for 70 minutes in the supine position after drinking the fluids.

Surface sampling concentration and reaction probe

DOEpatents

Van Berkel, Gary J; Elnaggar, Mariam S

2013-07-16

A method of analyzing a chemical composition of a specimen is described. The method can include providing a probe comprising an outer capillary tube and an inner capillary tube disposed co-axially within the outer capillary tube, where the inner and outer capillary tubes define a solvent capillary and a sampling capillary in fluid communication with one another at a distal end of the probe; contacting a target site on a surface of a specimen with a solvent in fluid communication with the probe; maintaining a plug volume proximate a solvent-specimen interface, wherein the plug volume is in fluid communication with the probe; draining plug sampling fluid from the plug volume through the sampling capillary; and analyzing a chemical composition of the plug sampling fluid with an analytical instrument. A system for performing the method is also described.

Transcapillary protein flux following blood volume modification in dog.

PubMed

Miki, K; Nose, H; Tanaka, Y; Morimoto, T

1984-01-01

The net fluid and protein movements between intravascular and interstitial space following blood withdrawal and retransfusion of 15% of circulating blood volume were measured in dogs using a continuous monitoring method of circulating blood volume. A significant (p less than 0.01) increase in transvascular fluid shift was observed after the start of blood withdrawal and a new equilibrium state was reached within 15 to 20 min. Associated with the fluid shift, a significant increase in plasma protein of about 1 g was observed. On the other hand, blood retransfusion caused significant (p less than 0.01) increases in the shift of fluid and protein from intravascular space to interstitial space. The magnitudes of the shift of fluid and protein were almost identical in both blood withdrawal and retransfusion. The Kedem-Katchalsky transport equation was applied to the results obtained in the present study in order to analyze the relative role of diffusion and convection and to estimate the reflection coefficient for protein. A significant (p less than 0.01) linear relationship was observed between fluid and protein movement. These results suggest that the convective process is involved in the shift of protein between intravascular and interstitial space observed after blood volume modification.

Difference gel electrophoresis (DiGE) identifies differentially expressed proteins in endoscopically-collected pancreatic fluid

PubMed Central

Paulo, Joao A.; Lee, Linda S.; Banks, Peter A.; Steen, Hanno; Conwell, Darwin L.

2012-01-01

Alterations in the pancreatic fluid proteome of individuals with chronic pancreatitis may offer insights into the development and progression of the disease. The endoscopic pancreas function test (ePFT) can safely collect large volumes of pancreatic fluid that are potentially amenable to proteomic analyses using difference gel electrophoresis (DiGE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pancreatic fluid was collected endoscopically using the ePFT method following secretin stimulation from three individuals with severe chronic pancreatitis and three chronic abdominal pain controls. The fluid was processed to minimize protein degradation and the protein profiles of each cohort, as determined by DiGE and LC-MS/MS, were compared. This DiGE-LC-MS/MS analysis reveals proteins that are differentially expressed in chronic pancreatitis compared to chronic abdominal pain controls. Proteins with higher abundance in pancreatic fluid from chronic pancreatitis individuals include: actin, desmoplankin, alpha-1-antitrypsin, SNC73, and serotransferrin. Those of relatively lower abundance include carboxypeptidase B, lipase, alpha-1-antichymotrypsin, alpha-2-macroglobulin, Arp2/3 subunit 4, glyceraldehyde-3-phosphate dehydrogenase, and protein disulfide isomerase. Endoscopic collection (ePFT) in tandem with DiGE-LC-MS/MS is a suitable approach for pancreatic fluid proteome analysis, however, further optimization of our protocol, as outlined herein, may improve proteome coverage in future analyses. PMID:21792986

Active Mixing in Microchannels using Surface Acoustic Wave Streaming on Lithium Niobate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branch, Darren W.; Meyer, Grant D.; Bourdon, Christopher Jay

2005-11-01

We present an active method for mixing fluid streams in microchannels at low Reynolds number with no dead volume. To overcome diffusion limited mixing in microchannels, surface acoustic wave streaming offers an extremely effective approach to rapidly homogenize fluids. This is a pivotal improvement over mixers based on complex 3D microchannels which have significant dead volume resulting in trapping or loss of sample. Our micromixer is integrable and highly adaptable for use within existing microfluidic devices. Surface acoustic wave devices fabricated on 128° YX LiNbO 3 permitted rapid mixing of flow streams as evidenced by fluorescence microscopy. Longitudinal waves createdmore » at the solid-liquid interface were capable of inducing strong nonlinear gradients within the bulk fluid. In the highly laminar regime (Re = 2), devices achieved over 93% mixing efficacy in less than a second. Micro-particle imaging velicometry was used to determine the mixing behavior in the microchannels and indicated that the liquid velocity can be controlled by varying the input power. Fluid velocities in excess of 3 cm•s -1 were measured in the main excitation region at low power levels (2.8mW). We believe that this technology will be pivotal in the development and advancement of microfluidic devices and applications.« less

Competition between reaction-induced expansion and creep compaction during gypsum formation: Experimental and numerical investigation

NASA Astrophysics Data System (ADS)

Skarbek, R. M.; Savage, H. M.; Spiegelman, M. W.; Kelemen, P. B.; Yancopoulos, D.

2017-12-01

Deformation and cracking caused by reaction-driven volume increase is an important process in many geological settings, however the conditions controlling these processes are poorly understood. The interaction of rocks with reactive fluids can change permeability and reactive surface area, leading to a large variety of feedbacks. Gypsum is an ideal material to study these processes. It forms rapidly at room temperature via bassanite hydration, and is commonly used as an analogue for rocks in high-temperature, high-pressure conditions. We conducted uniaxial strain experiments to study the effects of applied axial load on deformation and fluid flow during the formation of gypsum from bassanite. While hydration of bassanite to gypsum involves a solid volume increase, gypsum exhibits significant creep compaction when in contact with water. These two volume changing processes occur simultaneously during fluid flow through bassanite. We cold-pressed bassanite powder to form cylinders 2.5 cm in height and 1.2 cm in diameter. Samples were compressed with a static axial load of 0.01 to 4 MPa. Water infiltrated initially unsaturated samples through the bottom face and the height of the samples was recorded as a measure of the total volume change. We also performed experiments on pure gypsum samples to constrain the amount of creep observed in tests on bassanite hydration. At axial loads < 0.15 MPa, volume increase due to the reaction dominates and samples exhibit monotonic expansion. At loads > 1 MPa, creep in the gypsum dominates and samples exhibit monotonic compaction. At intermediate loads, samples exhibit alternating phases of compaction and expansion due to the interplay of the two volume changing processes. We observed a change from net compaction to net expansion at an axial load of 0.250 MPa. We explain this behavior with a simple model that predicts the strain evolution, but does not take fluid flow into account. We also implement a 1D poro-visco-elastic model of the imbibition process that includes the reaction and gypsum creep. We use the results of these models, with models of the creep rate in gypsum, to estimate the temperature dependence of the axial load where total strain transitions from compaction to expansion. Our results have implications for the depth dependence of reaction induced volume changes in the Earth.

Rapid Intravenous Rehydration Therapy in Children With Acute Gastroenteritis: A Systematic Review.

PubMed

Toaimah, Fatihi Hassan Soliman; Mohammad, Hala Mohammad Fathi

2016-02-01

Rapid intravenous (IV) rehydration is commonly used for the management of pediatric gastroenteritis in the emergency department. The current practice shows wide variation in the volume and rate of rapid IV hydration. The aim of this review was to assess the efficacy of rapid IV rehydration compared with standard method in children with gastroenteritis. MEDLINE (1946-2014), EMBASE (1974-2014), and CENTRAL via the Cochrane Library (Issue 8, 2014) were systematically searched to identify eligible studies. Inclusion criteria were randomized controlled trials of rapid IV rehydration in children with gastroenteritis. A total of 1513 articles were retrieved, and our inclusion criteria were met by 3 studies, with a total of 464 participants. The percentage of children who were successfully rehydrated and tolerated oral fluids at 2 to 4 hours after starting IV fluid therapy ranged from 69% to 100% in both rapid IV rehydration and standard method. Time to discharge ranged from 2 to 6 hours (rapid rehydration) versus 2 to 5 hours (standard rehydration). Emergency department revisits ranged from 3% to 16% (rapid rehydration) versus 5% to 14% (standard). Summarized results suggested that rapid IV rehydration may be associated with longer time-to-discharge and higher readmission rates. The new evidence fails to demonstrate superiority of large-volume (60 mL/kg/h) over standard (20 mL/kg/h) IV rehydration. Standard volume IV rehydration for 1 to 4 hours followed by oral hydration or maintenance IV fluids seems sufficient for most children with gastroenteritis requiring IV fluid administration. However, more evidence is needed to establish an optimal IV rehydration regimen.

Plasma volume and blood viscosity during 4 h sitting in a dry environment: effect of prehydration.

PubMed

Doi, Tatsuya; Sakurai, Masao; Hamada, Koichiro; Matsumoto, Keitaro; Yanagisawa, Kae; Kikuchi, Noriaki; Morimoto, Taketoshi; Greenleaf, John E

2004-06-01

Deep vein thrombosis and pulmonary thromboembolism are potential problems for travelers, including those who fly. We hypothesized that prehydration with an electrolyte-glucose beverage (EGB) would be better than water for maintaining body fluid balance and preventing increased blood viscosity in immobilized men. There were 12 healthy men (24-38 yr) who participated in crossover trials of prehydration using EGB and H2O as well as a control condition (Con) with no prehydration. Fluid intake was set at 6 ml x kg(-1) body weight (mean 418 ml). For each trial, subjects sat for 4 h at a dry-bulb temperature of 23.0-23.5 degrees C and a relative humidity of 18-36%. Plasma volume (PV) and whole blood viscosity (Bvis) were determined every hour; routine laboratory hematological tests, urine volume, and body weight were recorded at 2 h and 4 h. For Con, subjects lost approximately 110 ml h(-1); at 2 h, PV had decreased significantly by 3.4%, and Bvis had increased significantly by 9.3%, with no further change at 4 h. For prehydration, retention of the consumed fluid at 2 h was significantly higher for EGB (57%) than for H2O (38%), while both drinks prevented significant change in PV and Bvis. There were no significant differences between trials in coagulation variables, but Bvis measured at higher shear rates for EGB were significantly attenuated compared with Con. EGB and water prevented the increase of blood viscosity that occurred without prehydration. EGB was better than water for maintaining body fluid balance and preventing hypovolemia.

Injection-induced moment release can also be aseismic

USGS Publications Warehouse

McGarr, Arthur; Barbour, Andrew J.

2018-01-01

The cumulative seismic moment is a robust measure of the earthquake response to fluid injection for injection volumes ranging from 3100 to about 12 million m3. Over this range, the moment release is limited to twice the product of the shear modulus and the volume of injected fluid. This relation also applies at the much smaller injection volumes of the field experiment in France reported by Guglielmi, et al. (2015) and laboratory experiments to simulate hydraulic fracturing described by Goodfellow, et al. (2015). In both of these studies, the relevant moment release for comparison with the fluid injection was aseismic and consistent with the scaling that applies to the much larger volumes associated with injection-induced earthquakes with magnitudes extending up to 5.8. Neither the micro-earthquakes, at the site in France, nor the acoustic emission in the laboratory samples contributed significantly to the deformation due to fluid injection.

Use, misuse and abuse of diuretics.

PubMed

Bartoli, Ettore; Rossi, Luca; Sola, Daniele; Castello, Luigi; Sainaghi, Pier Paolo; Smirne, Carlo

2017-04-01

Resolution of edema requires a correct interpretation of body fluids-related renal function, to excrete the excess volume while restoring systemic hemodynamics and avoiding renal failure. In heart failure, the intensive diuresis should be matched by continuous fluids refeeding from interstitium to plasma, avoiding central volume depletion. The slowly reabsorbed ascites cannot refeed this contracted volume in cirrhosis: the ensuing activation of intrathoracic receptors, attended by increased adrenergic and Renin release, causes more avid sodium retention, producing a positive fluid and Na balance in the face of continuous treatment. High-dose-furosemide creates a defect in tubular Na causing diuresis adequate to excrete the daily water and electrolyte load in Chronic Renal Failure. Diuretic treatment requires care, caution and bedside "tricks" aimed at minimizing volume contraction by correctly assessing the homeostatic system of body fluids and related renal hemodynamics. Copyright © 2017 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Cardiovascular dynamics during the initial period of head-down tilt

NASA Technical Reports Server (NTRS)

Tomaselli, Clare Marie; Kenney, Richard A.; Frey, Mary Anne Bassett; Hoffler, G. Wyckliffe

1987-01-01

The cardiovascular response to 1 h of 60-deg head-down tilt was studied in 12 male subjects, ages 30-39 years, to simulate the early effects of weightlessness. Fluid shifts, hemodynamic variables, and indices of myocardial contractility were evaluated by utilizing electrocardiography, systolic time intervals, impedance cardiography, sphygmomanometry, and measurement of calf circumference. Most cardiovascular variables remained stable throughout the initial 30 min of the protocol, even though translocation of fluid from the legs to the thorax commenced immediately with the onset of head-down tilt. In contrast, minutes 30-60 were characterized by reduced stroke volume, cardiac output, mean stroke ejection rate, and Heather index concomitant with an elevation in mean arterial pressure. Intrathoracic fluid volume continued to increase, while leg volume continued to decrease. This latter physiological response suggests intrathoracic sequestration of fluid volume; blood was apparently redistributed to the pulmonary circulation rather than being retained in the great veins.

Differences in and correlations between cognitive abilities and brain volumes in healthy control, mild cognitive impairment, and Alzheimer disease groups.

PubMed

Chung, Soon-Cheol; Choi, Mi-Hyun; Kim, Hyung-Sik; Lee, Jung-Chul; Park, Sung-Jun; Jeong, Ul-Ho; Baek, Ji-Hye; Gim, Seon-Young; Choi, Young Chil; Lee, Beob-Yi; Lim, Dae-Woon; Kim, Boseong

2016-05-01

The purpose of this study is to investigate differences in and correlations between cognitive abilities and brain volumes in healthy control (HC), mild cognitive impairment (MCI), and Alzheimer's disease (AD) groups. The Korean Version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD-K), which is used to diagnose AD, was used to measure the cognitive abilities of the study subjects, and the volumes of typical brain components related to AD diagnosis-cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM)-were acquired. Of the CERAD-K subtests, the Boston Naming Test distinguished significantly among the HC, MCI, and AD groups. GM and WM volumes differed significantly among the three groups. There was a significant positive correlation between Boston Naming Test scores and GM and WM volumes. In conclusion, the Boston Naming Test and GM and WM brain volumes differentiated the three tested groups accurately, and there were strong correlations between Boston Naming Test scores and GM and WM volumes. These results will help to establish a test method that differentiates the three groups accurately and is economically feasible. © 2016 Wiley Periodicals, Inc.

Glacial uplift: fluid injection beneath an elastic sheet on a poroelastic substrate

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Hewitt, Duncan; Chini, Greg

2016-11-01

Supraglacial lakes can drain to the base of glaciers extremely rapidly, causing localised uplift of the surrounding glacier and affecting its sliding velocity. The means by which large volumes of drained water interact with and leak into the subglacial hydrological system is unclear, as is the role of the basal till. A theoretical study of the spread of fluid injected below an elastic sheet (the ice) is presented, where the ice lies above, and initially compresses, a deformable poroelastic layer. As pressurized fluid is injected, the deformable layer swells to accommodate more fluid. If sufficient fluid is injected, a 'blister' of fluid forms above the layer, causing the overburden to lift off the base. The flow is controlled by the local pressure drop across the tip of this blister, which depends subtly on both the flow of fluid through the porous layer below the tip, and on poroelastic deformation in the till ahead of the tip. The spreading behaviour and dependence on key parameters is analysed. Predictions of the model are compared to field measurements of uplift from draining glacial lakes in Greenland.

Hybrid mesh finite volume CFD code for studying heat transfer in a forward-facing step

NASA Astrophysics Data System (ADS)

Jayakumar, J. S.; Kumar, Inder; Eswaran, V.

2010-12-01

Computational fluid dynamics (CFD) methods employ two types of grid: structured and unstructured. Developing the solver and data structures for a finite-volume solver is easier than for unstructured grids. But real-life problems are too complicated to be fitted flexibly by structured grids. Therefore, unstructured grids are widely used for solving real-life problems. However, using only one type of unstructured element consumes a lot of computational time because the number of elements cannot be controlled. Hence, a hybrid grid that contains mixed elements, such as the use of hexahedral elements along with tetrahedral and pyramidal elements, gives the user control over the number of elements in the domain, and thus only the domain that requires a finer grid is meshed finer and not the entire domain. This work aims to develop such a finite-volume hybrid grid solver capable of handling turbulence flows and conjugate heat transfer. It has been extended to solving flow involving separation and subsequent reattachment occurring due to sudden expansion or contraction. A significant effect of mixing high- and low-enthalpy fluid occurs in the reattached regions of these devices. This makes the study of the backward-facing and forward-facing step with heat transfer an important field of research. The problem of the forward-facing step with conjugate heat transfer was taken up and solved for turbulence flow using a two-equation model of k-ω. The variation in the flow profile and heat transfer behavior has been studied with the variation in Re and solid to fluid thermal conductivity ratios. The results for the variation in local Nusselt number, interface temperature and skin friction factor are presented.

Goal-directed fluid therapy in major elective rectal surgery.

PubMed

Srinivasa, Sanket; Taylor, Matthew H G; Singh, Primal P; Lemanu, Daniel P; MacCormick, Andrew D; Hill, Andrew G

2014-12-01

Goal-Directed Fluid Therapy (GDFT) has been previously shown to decrease complications and hospital length of stay in major colorectal surgery but the data are not specific to rectal surgery and may be potentially outdated. This study investigated whether GDFT provides clinical benefits in patients undergoing major elective rectal surgery. There were 81 consecutive patients in this cohort study. Twenty-seven patients were allotted to GDFT using the Oesophageal Doppler Monitor (ODM) and received boluses of colloid fluid based on corrected flow time and stroke volume. These patients were compared with a historical cohort of the previous 54 patients managed without the ODM. The primary endpoint of the study was 30-day total complications which were defined and graded. Secondary endpoints included hospital length of stay (LOS) and fluid volumes administered. There were no differences at baseline between the two groups. Patients in the treatment group received a higher volume of colloid fluids (1000 mL vs. 500 mL; p < 0.01) but there were no differences in overall fluid volumes administered intraoperatively (3000 mL vs. 3000 mL; p = 0.41). A non-significant trend (p = 0.06) suggested that patients allotted to GDFT had decreased fluid requirement in the first 24 h after surgery. There were no differences in median total fluid volumes (12700 mL vs. 10407 mL; p = 0.95), total complications (22 [81%] vs. 44 [81%]; p = 1.00) or median hospital LOS (9 days vs. 10 days; p = 0.92) between the two groups. Intraoperative GDFT did not improve clinical outcomes following major elective rectal surgery. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

White matter lesions characterise brain involvement in moderate to severe chronic obstructive pulmonary disease, but cerebral atrophy does not.

PubMed

Spilling, Catherine A; Jones, Paul W; Dodd, James W; Barrick, Thomas R

2017-06-19

Brain pathology is relatively unexplored in chronic obstructive pulmonary disease (COPD). This study is a comprehensive investigation of grey matter (GM) and white matter (WM) changes and how these relate to disease severity and cognitive function. T1-weighted and fluid-attenuated inversion recovery images were acquired for 31 stable COPD patients (FEV 1 52.1% pred., PaO 2 10.1 kPa) and 24 age, gender-matched controls. T1-weighted images were segmented into GM, WM and cerebrospinal fluid (CSF) tissue classes using a semi-automated procedure optimised for use with this cohort. This procedure allows, cohort-specific anatomical features to be captured, white matter lesions (WMLs) to be identified and includes a tissue repair step to correct for misclassification caused by WMLs. Tissue volumes and cortical thickness were calculated from the resulting segmentations. Additionally, a fully-automated pipeline was used to calculate localised cortical surface and gyrification. WM and GM tissue volumes, the tissue volume ratio (indicator of atrophy), average cortical thickness, and the number, size, and volume of white matter lesions (WMLs) were analysed across the whole-brain and regionally - for each anatomical lobe and the deep-GM. The hippocampus was investigated as a region-of-interest. Localised (voxel-wise and vertex-wise) variations in cortical gyrification, GM density and cortical thickness, were also investigated. Statistical models controlling for age and gender were used to test for between-group differences and within-group correlations. Robust statistical approaches ensured the family-wise error rate was controlled in regional and local analyses. There were no significant differences in global, regional, or local measures of GM between patients and controls, however, patients had an increased volume (p = 0.02) and size (p = 0.04) of WMLs. In patients, greater normalised hippocampal volume positively correlated with exacerbation frequency (p = 0.04), and greater WML volume was associated with worse episodic memory (p = 0.05). A negative relationship between WML and FEV 1 % pred. approached significance (p = 0.06). There was no evidence of cerebral atrophy within this cohort of stable COPD patients, with moderate airflow obstruction. However, there were indications of WM damage consistent with an ischaemic pathology. It cannot be concluded whether this represents a specific COPD, or smoking-related, effect.

Guiding principles of fluid and volume therapy.

PubMed

Aditianingsih, Dita; George, Yohanes W H

2014-09-01

Fluid therapy is a core concept in the management of perioperative and critically ill patients for maintenance of intravascular volume and organ perfusion. Recent evidence regarding the vascular barrier and its role in terms of vascular leakage has led to a new concept for fluid administration. The choice of fluid used should be based on the fluid composition and the underlying pathophysiology of the patient. Avoidance of both hypo- and hypervolaemia is essential when treating circulatory failure. In daily practice, the assessment of individual thresholds in order to optimize cardiac preload and avoid hypovolaemia or deleterious fluid overload remains a challenge. Liberal versus restrictive fluid management has been challenged by recent evidence, and the ideal approach appears to be goal-directed fluid therapy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Current purpose and practice of hypertonic saline in neurosurgery: a review of the literature.

PubMed

Thongrong, Cattleya; Kong, Nicolas; Govindarajan, Barani; Allen, Duane; Mendel, Ehud; Bergese, Sergio D

2014-12-01

To review and summarize controversies and current concepts regarding the use of hypertonic saline during the perioperative period in neurosurgery. Relevant literature was searched on PubMed and Scopus electronic databases to identify all studies that have investigated the use of hypertonic saline in neurosurgery. Fluid management during the course of neurosurgical practice has been debated at length, especially strategies to control intracranial pressure and small volume resuscitation. The goal of fluid therapy includes minimizing cerebral edema, preserving intravascular volume, and maintaining cerebral perfusion pressure. Mannitol is widely recognized as the gold standard for treating intracranial hypertension but can result in systemic hypotension. Thus, hypertonic saline provides volume expansion and may improve cerebral and systemic hemodynamics. Recently published prospective data, however, regarding the use of osmotic agents fails to establish clear guidelines in neurosurgical patients. We suggest that hypertonic saline will emerge as an alternative to mannitol, especially for a long-term use or multiple doses are needed and lead to a great opportunity for collaborative research. Copyright © 2014 Elsevier Inc. All rights reserved.

Multicenter Study of Brain Volume Abnormalities in Children and Adolescent-Onset Psychosis

PubMed Central

Reig, Santiago; Parellada, Mara; Castro-Fornieles, Josefina; Janssen, Joost; Moreno, Dolores; Baeza, Inmaculada; Bargalló, Nuria; González-Pinto, Ana; Graell, Montserrat; Ortuño, Felipe; Otero, Soraya; Arango, Celso; Desco, Manuel

2011-01-01

The goal of the study is to determine the extent of structural brain abnormalities in a multicenter sample of children and adolescents with a recent-onset first episode of psychosis (FEP), compared with a sample of healthy controls. Total brain and lobar volumes and those of gray matter (GM), white matter, and cerebrospinal fluid (CSF) were measured in 92 patients with a FEP and in 94 controls, matched for age, gender, and years of education. Male patients (n = 64) showed several significant differences when compared with controls (n = 61). GM volume in male patients was reduced in the whole brain and in frontal and parietal lobes compared with controls. Total CSF volume and frontal, temporal, and right parietal CSF volumes were also increased in male patients. Within patients, those with a further diagnosis of “schizophrenia” or “other psychosis” showed a pattern similar to the group of all patients relative to controls. However, bipolar patients showed fewer differences relative to controls. In female patients, only the schizophrenia group showed differences relative to controls, in frontal CSF. GM deficit in male patients with a first episode correlated with negative symptoms. Our study suggests that at least part of the GM deficit in children and adolescent-onset schizophrenia and in other psychosis occurs before onset of the first positive symptoms and that, contrary to what has been shown in children-onset schizophrenia, frontal GM deficits are probably present from the first appearance of positive symptoms in children and adolescents. PMID:20478821

Self-propulsion of a body with rigid surface and variable coefficient of lift in a perfect fluid

NASA Astrophysics Data System (ADS)

Ramodanov, Sergey M.; Tenenev, Valentin A.; Treschev, Dmitry V.

2012-11-01

We study the system of a 2D rigid body moving in an unbounded volume of incompressible, vortex-free perfect fluid which is at rest at infinity. The body is equipped with a gyrostat and a so-called Flettner rotor. Due to the latter the body is subject to a lifting force (Magnus effect). The rotational velocities of the gyrostat and the rotor are assumed to be known functions of time (control inputs). The equations of motion are presented in the form of the Kirchhoff equations. The integrals of motion are given in the case of piecewise continuous control. Using these integrals we obtain a (reduced) system of first-order differential equations on the configuration space. Then an optimal control problem for several types of the inputs is solved using genetic algorithms.

Small-Portion Water Dispenser

NASA Technical Reports Server (NTRS)

Joerns, J. C.

1986-01-01

Pressure regulated and flow timed to control amount dispensed. Dispenser provides measured amount of water for reconstituting dehydrated foods and beverages. Dispenser holds food or beverage package while being filled with either cold or room-temperature water. Other uses might include dispensing of fluids or medicine. Pressure regulator in dispenser reduces varying pressure of water supply to constant pressure. Electronic timer stops flow after predetermined length of time. Timed flow at regulated pressure ensures controlled volume of water dispensed.

Investigation of the Capture of Magnetic Particles From High-Viscosity Fluids Using Permanent Magnets.

PubMed

Garraud, Alexandra; Velez, Camilo; Shah, Yash; Garraud, Nicolas; Kozissnik, Bettina; Yarmola, Elena G; Allen, Kyle D; Dobson, Jon; Arnold, David P

2016-02-01

This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a "collection volume" with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. The viscosity of the fluid strongly influences the velocity of the magnetic particles toward the magnet, hence, the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Numerical results showed good agreement with in vitro experimental magnetic collection results. In the long term, this paper aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient.

The use of cardiac output monitoring to guide the administration of intravenous fluid during hyperthermic intraperitoneal chemotherapy.

PubMed

Thanigaimani, K; Mohamed, F; Cecil, T; Moran, B J; Bell, J

2013-12-01

The optimal strategy for intravenous (IV) fluid management during administration of hyperthermic intraperitoneal chemotherapy (HIPEC) is unclear. In this prospective study we describe the use of a LiDCOrapid™ (LiDCO, Cambridge, UK) cardiac output monitor to guide IV fluid management during cytoreductive surgery (CRS) with HIPEC. The aim of this study was to determine whether cardiac output monitoring will allow close maintenance of physiological parameters during the HIPEC phase. Twenty-five patients who underwent CRS combined with HIPEC were included in the study. Intra-operative IV fluid boluses were titrated using parameters measured by the LiDCOrapid™ monitor. Stroke volume variation was maintained below 10% with fluid boluses and mean arterial pressure was maintained within 20% of the baseline figure with vasopressors. There was no significant change in heart rate and cardiac output. The systemic vascular resistance dropped from an average of 966 dyn.s/cm-5 to 797 dyn s/cm(5) at 60 min during the HIPEC phase (P = 0.62) despite an increase in the dose of phenylepherine. The average total volume of fluid given was 748 ml in the first 30 min and 630 ml in the second 30 min with an average urine output of 307 and 445 ml, respectively. The change in lactate levels was not statistically or clinically significant. LiDCOrapid™ is an effective noninvasive tool for guiding fluid management in this population. It allows the anaesthesiologist to maintain tight control of essential physiological parameters during a phase of the procedure in which there is a risk of renal injury. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain and Ireland.

Bioimpedance, dry weight and blood pressure control: new methods and consequences.

PubMed

Kuhlmann, Martin K; Zhu, Fansan; Seibert, E; Levin, Nathan W

2005-11-01

Chronic overhydration contributes to the development of left ventricular hypertrophy and a high cardiovascular mortality in end-stage renal disease. Assessment of dry weight is highly dependent on clinical assessment. Bioimpedance technology offers the potential to quantify body fluid compartments and to facilitate dry weight prescription. This review covers recent innovative approaches to dry weight assessment using bioimpedance technology. Three different bioimpedance approaches to determine dry weight have been published. The normovolemic/hypervolemic slope method applies whole body multifrequency bioimpedance to assess predialysis total body extracellular fluid volume and compares the extracellular fluid volume/body weight relation at hypervolemia with the standard value in normovolemic individuals. The resistance-reactance graph method uses whole body single frequency bioimpedance for assessment of hydration state and nutritional status from height-adjusted resistance and reactance. The resulting resistance-reactance vector is set in relation to a distribution range in a normovolemic population. An alternative method uses segmental bioimpedance in the form of continuous intradialytic calf bioimpedance to record changes in calf extracellular volume during dialysis. Dry weight by this method is defined as the weight at which calf extracellular volume is not further reduced despite ongoing ultrafiltration. Although promising, none of these methods has gained much popularity, probably due to the difficulties in understanding bioimpedance and the lack of gold standard methods for dry weight determination. Bioimpedance will improve dry weight assessment, but further refinement of the methods as well as large-scale clinical studies to demonstrate the accuracy and the clinical value of objective dry weight determination are needed.

Effects of saline or albumin resuscitation on standard coagulation tests.

PubMed

Bellomo, Rinaldo; Morimatsu, Hiroshi; Presneill, Jeff; French, Craig; Cole, Louise; Story, David; Uchino, Shigehiko; Naka, Toshio; Finfer, Simon; Cooper, D James; Myburgh, John

2009-12-01

To explore whether fluid resuscitation with normal saline or 4% albumin is associated with differential changes in routine clinical coagulation tests. Substudy from a large double-blind randomised controlled trial, the SAFE (Saline versus Albumin Fluid Evaluation) study. Three general intensive care units. Cohort of 687 critically ill patients. We randomly allocated patients to receive either 4% human albumin or normal saline for fluid resuscitation, and collected demographic and haematological data. Albumin was administered to 338 patients and saline to 349. At baseline, the two groups had similar mean activated partial thromboplastin time (APTT) of 37.2 s (albumin) v 39.1 s (saline); mean international normalised ratio (INR) of 1.38 v 1.34, and mean platelet count of 244 x 10(9)/L v 249 x 10(9)/L. After randomisation, during the first day of treatment, the APTT in the albumin group was prolonged by a mean of 2.7 s, but shortened slightly by a mean of -0.9 s in the saline group. The INR did not change in either group, while the platelet count decreased transiently in both groups. Using multivariate analysis of covariance to account for baseline coagulation status, albumin fluid resuscitation (P = 0.01) and a greater overall volume of resuscitation (P = 0.03) were independently associated with prolongation of APTT during the first day. Administration of albumin or of larger fluid volumes is associated with a prolongation of APTT. In ICU patients, the choice and amount of resuscitation fluid may affect a routinely used coagulation test.

Comparison of urodynamic volume measurements using room and body temperature saline: a double-blinded randomized crossover study design.

PubMed

Gehrich, Alan Paul; Hill, Micah J; McWilliams, Grant D E; Larsen, Wilma; McCartin, Tamarin

2012-01-01

Urodynamic studies, routinely performed in women with lower urinary tract symptoms, have a large impact on clinical decision making. Unfortunately, these studies are insensitive in reproducing idiopathic detrusor overactivity (IDO). We set out to examine whether serial cystometry with different distending fluid temperatures could better reproduce symptoms. Eighty-six women were enrolled in a double-blinded, randomized, crossover study. Two cystometries were performed in series, starting with either body temperature fluid (BTF) or room temperature fluid (RTF) and then repeating cystometry with the other temperature fluid. Primary outcomes included first sensation, first urge, and maximum cystometric capacity. Secondary outcomes included subjective sensation of bladder discomfort and the incidence of IDO. In aggregate, the temperature of the fluid did not affect volumes of bladder sensation. There were no differences in self-reported bladder irritation or IDO between the different temperature fluids. There was a significant carryover effect with BTF. BTF administered first reached sensory thresholds at lower volumes than when it was administered second after RTF. Room temperature fluid cystometry showed no statistical difference in volume between first fill and second fill. Idiopathic detrusor overactivity contractions were seen in 9% of studies and were not affected by period or temperature. These data suggest that BTF and RTF independently do not affect bladder sensory thresholds. The periodicity in combination with varying fluid temperature is of greater impact. This study documents that changes in temperature of the distending fluid from BTF to RTF or vice versa likely do not provoke IDO contractions.

Application of parallel distributed Lagrange multiplier technique to simulate coupled Fluid-Granular flows in pipes with varying Cross-Sectional area

DOE PAGES

Kanarska, Yuliya; Walton, Otis

2015-11-30

Fluid-granular flows are common phenomena in nature and industry. Here, an efficient computational technique based on the distributed Lagrange multiplier method is utilized to simulate complex fluid-granular flows. Each particle is explicitly resolved on an Eulerian grid as a separate domain, using solid volume fractions. The fluid equations are solved through the entire computational domain, however, Lagrange multiplier constrains are applied inside the particle domain such that the fluid within any volume associated with a solid particle moves as an incompressible rigid body. The particle–particle interactions are implemented using explicit force-displacement interactions for frictional inelastic particles similar to the DEMmore » method with some modifications using the volume of an overlapping region as an input to the contact forces. Here, a parallel implementation of the method is based on the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) library.« less

Rapid intravenous rehydration of children with acute gastroenteritis and dehydration: a systematic review and meta-analysis.

PubMed

Iro, M A; Sell, T; Brown, N; Maitland, K

2018-02-09

The World Health Organization (WHO) recommends rapid intravenous rehydration, using fluid volumes of 70-100mls/kg over 3-6 h, with some of the initial volume given rapidly as initial fluid boluses to treat hypovolaemic shock for children with acute gastroenteritis (AGE) and severe dehydration. The evidence supporting the safety and efficacy of rapid versus slower rehydration remains uncertain. We conducted a systematic review of randomised controlled trials (RCTs) on 11th of May 2017 comparing different rates of intravenous fluid therapy in children with AGE and moderate or severe dehydration, using standard search terms. Two authors independently assessed trial quality and extracted data. Non-RCTs and non-English articles were excluded. The primary endpoint was mortality and secondary endpoints included adverse events (safety) and treatment efficacy. Of the 1390 studies initially identified, 18 were assessed for eligibility. Of these, 3 studies (n = 464) fulfilled a priori criteria for inclusion; most studied children with moderate dehydration and none were conducted in resource-poor settings. Volumes and rates of fluid replacement varied from 20 to 60 ml/kg given over 1-2 h (fast) versus 2-4 h (slow). There was substantial heterogeneity in methodology between the studies with only one adjudicated to be of high quality. There were no deaths in any study. Safety endpoints only identified oedema (n = 6) and dysnatraemia (n = 2). Pooled analysis showed no significant difference between the rapid and slow intravenous rehydration groups for the proportion of treatment failures (N = 468): pooled RR 1.30 (95% CI: 0.87, 1.93) and the readmission rates (N = 439): pooled RR 1.39 (95% CI: 0.68, 2.85). Despite wide implementation of WHO Plan C guideline for severe AGE, we found no clinical evaluation in resource-limited settings, and only limited evaluation of the rate and volume of rehydration in other parts of the world. Recent concerns over aggressive fluid expansion warrants further research to inform guidelines on rates of intravenous rehydration therapy for severe AGE.

The preliminary exploration of 64-slice volume computed tomography in the accurate measurement of pleural effusion.

PubMed

Guo, Zhi-Jun; Lin, Qiang; Liu, Hai-Tao; Lu, Jun-Ying; Zeng, Yan-Hong; Meng, Fan-Jie; Cao, Bin; Zi, Xue-Rong; Han, Shu-Ming; Zhang, Yu-Huan

2013-09-01

Using computed tomography (CT) to rapidly and accurately quantify pleural effusion volume benefits medical and scientific research. However, the precise volume of pleural effusions still involves many challenges and currently does not have a recognized accurate measuring. To explore the feasibility of using 64-slice CT volume-rendering technology to accurately measure pleural fluid volume and to then analyze the correlation between the volume of the free pleural effusion and the different diameters of the pleural effusion. The 64-slice CT volume-rendering technique was used to measure and analyze three parts. First, the fluid volume of a self-made thoracic model was measured and compared with the actual injected volume. Second, the pleural effusion volume was measured before and after pleural fluid drainage in 25 patients, and the volume reduction was compared with the actual volume of the liquid extract. Finally, the free pleural effusion volume was measured in 26 patients to analyze the correlation between it and the diameter of the effusion, which was then used to calculate the regression equation. After using the 64-slice CT volume-rendering technique to measure the fluid volume of the self-made thoracic model, the results were compared with the actual injection volume. No significant differences were found, P = 0.836. For the 25 patients with drained pleural effusions, the comparison of the reduction volume with the actual volume of the liquid extract revealed no significant differences, P = 0.989. The following linear regression equation was used to compare the pleural effusion volume (V) (measured by the CT volume-rendering technique) with the pleural effusion greatest depth (d): V = 158.16 × d - 116.01 (r = 0.91, P = 0.000). The following linear regression was used to compare the volume with the product of the pleural effusion diameters (l × h × d): V = 0.56 × (l × h × d) + 39.44 (r = 0.92, P = 0.000). The 64-slice CT volume-rendering technique can accurately measure the volume in pleural effusion patients, and a linear regression equation can be used to estimate the volume of the free pleural effusion.

The yield of different pleural fluid volumes for Mycobacterium tuberculosis culture.

PubMed

von Groote-Bidlingmaier, Florian; Koegelenberg, Coenraad Frederik; Bolliger, Chris T; Chung, Pui Khi; Rautenbach, Cornelia; Wasserman, Elizabeth; Bernasconi, Maurizio; Friedrich, Sven Olaf; Diacon, Andreas Henri

2013-03-01

We prospectively compared the culture yields of two pleural fluid volumes (5 and 100 ml) inoculated in liquid culture medium in 77 patients of whom 58 (75.3%) were diagnosed with pleural tuberculosis. The overall fluid culture yield was high (60.3% of cases with pleural tuberculosis). The larger volume had a faster time to positivity (329 vs 376 h, p=0.055) but its yield was not significantly higher (53.5% vs 50%; p=0.75). HIV-positive patients were more likely to have positive cultures (78.9% vs 51.5%; p=0.002).

Evaluation of the use of automatic exposure control and automatic tube potential selection in low-dose cerebrospinal fluid shunt head CT.

PubMed

Wallace, Adam N; Vyhmeister, Ross; Bagade, Swapnil; Chatterjee, Arindam; Hicks, Brandon; Ramirez-Giraldo, Juan Carlos; McKinstry, Robert C

2015-06-01

Cerebrospinal fluid shunts are primarily used for the treatment of hydrocephalus. Shunt complications may necessitate multiple non-contrast head CT scans resulting in potentially high levels of radiation dose starting at an early age. A new head CT protocol using automatic exposure control and automated tube potential selection has been implemented at our institution to reduce radiation exposure. The purpose of this study was to evaluate the reduction in radiation dose achieved by this protocol compared with a protocol with fixed parameters. A retrospective sample of 60 non-contrast head CT scans assessing for cerebrospinal fluid shunt malfunction was identified, 30 of which were performed with each protocol. The radiation doses of the two protocols were compared using the volume CT dose index and dose length product. The diagnostic acceptability and quality of each scan were evaluated by three independent readers. The new protocol lowered the average volume CT dose index from 15.2 to 9.2 mGy representing a 39 % reduction (P < 0.01; 95 % CI 35-44 %) and lowered the dose length product from 259.5 to 151.2 mGy/cm representing a 42 % reduction (P < 0.01; 95 % CI 34-50 %). The new protocol produced diagnostically acceptable scans with comparable image quality to the fixed parameter protocol. A pediatric shunt non-contrast head CT protocol using automatic exposure control and automated tube potential selection reduced patient radiation dose compared with a fixed parameter protocol while producing diagnostic images of comparable quality.

The effect of intraocular gas and fluid volumes on intraocular pressure.

PubMed

Simone, J N; Whitacre, M M

1990-02-01

Large increases in the intraocular pressure (IOP) of postoperative gas-containing eyes may require the removal of gas or fluid to reduce the IOP to the normal range. Application of the ideal gas law to Friedenwald's equation provides a mathematical model of the relationship between IOP, intraocular gas and fluid volumes, and the coefficient of scleral rigidity. This mathematic model shows that removal of a given volume of gas or fluid produces an identical decrease in IOP and that the more gas an eye contains, the greater the volume reduction necessary to reduce the pressure. Application of the model shows that the effective coefficient of scleral rigidity is low (mean K, 0.0021) in eyes with elevated IOP that have undergone vitrectomy and retinal cryopexy and very low (mean K, 0.0013) in eyes with elevated IOP that have undergone placement of a scleral buckle and band. By using the appropriate mean coefficient of rigidity, the volume of material to be aspirated to produce a given decrease in IOP can be predicted with clinically useful accuracy.

Blood volume reduction counteracts fluid shifts in water immersion

NASA Technical Reports Server (NTRS)

Simanonok, Karl E.; Bernauer, Edmund

1993-01-01

Six healthy men were bled by 15 percent of their total blood volume (TBV) before 7 h of seated water immersion, to test the hypothesis that some of the major physiological responses to an expansion of central blood volume can be counteracted by prior reduction of TBV. Subjects were their own controls under two conditions: seated dry in air and seated immersed to the suprasternal notch in water. Immersion without prior reduction of TBV Wet Control (WC) caused a statistically significant 22-percent increase in cardiac output (CO), 368-percent increase in urine production, and 200-percent increase in sodium excretion relative to dry control (DC) sessions. When TBV was reduced before immersion, CO was the same as during DC sessions; however there were significant increases above DC in urine flow (+73 percent) and sodium excretion (+120 percent), although they were significantly reduced from WC values. Potassium excretion was similar during DC and WC sessions, but was significantly increased (+75 percent) when subjects were immersed after 15-percent reduction of TBV.

Volumetric Analysis of Gingival Crevicular Fluid and Peri-Implant Sulcus Fluid in Healthy and Diseased Sites: A Cross-Sectional Split-Mouth Pilot Study

PubMed Central

Bevilacqua, Lorenzo; De Biasi, Matteo; Lorenzon, Maria Giulia; Frattini, Costanza; Angerame, Daniele

2016-01-01

Background: Researchers have recently drawn attention to the analysis of gingival crevicular fluid (GCF) and peri-implant sulcus fluid (PISF) for the implementation of the diagnosis of periodontal and peri-implant disease. Nevertheless, the measurements of volume and biomarkers concentration can be critically biased when data collected from studies with parallel group design are compared, given the technical difficulties, methodological variables, as well as the variability of crevicular fluid characteristics among different individuals. Objective: The aim of the present study was to assess the GCF and PISF volumes in healthy and diseased sites belonging to the same patient. Method: Ten patients presenting a periodontally healthy tooth, a tooth with periodontitis, an implant with healthy peri-implant tissues and an implant with peri-implantitis were enrolled. Samples of GCF and PISF were collected from each site of interest and their volume measured with a Periotron 8000 device. Non-parametric statistical analysis was performed to test the significance of the differences in GCF and PISF volumes between i) sites of teeth and dental implants with the same condition of health or disease and ii) healthy and diseased sites of both teeth and dental implants subgroups. The correlation between probing pocket depth (PPD) and fluid production was also tested (p<0.05). Results: Healthy periodontal and peri-implant tissues produced comparable amounts of fluid that was significantly lower than in diseased sites (p<0.05). In the presence of diagnosed disease, the volumes of GCF and PISF were similar, too. The correlation between PPD and fluid production was significant only in healthy sites (PPD/GCF, ρ=0.890, p<0.001; PPD/PISF, ρ=0.810; p<0.005). Conclusion: The periodontal and peri-implant tissues behaved similarly in terms of fluid production in condition of both health and active disease. PMID:27335614

Neuroanatomical correlates of intelligence in healthy young adults: the role of basal ganglia volume.

PubMed

Rhein, Cosima; Mühle, Christiane; Richter-Schmidinger, Tanja; Alexopoulos, Panagiotis; Doerfler, Arnd; Kornhuber, Johannes

2014-01-01

In neuropsychiatric diseases with basal ganglia involvement, higher cognitive functions are often impaired. In this exploratory study, we examined healthy young adults to gain detailed insight into the relationship between basal ganglia volume and cognitive abilities under non-pathological conditions. We investigated 137 healthy adults that were between the ages of 21 and 35 years with similar educational backgrounds. Magnetic resonance imaging (MRI) was performed, and volumes of basal ganglia nuclei in both hemispheres were calculated using FreeSurfer software. The cognitive assessment consisted of verbal, numeric and figural aspects of intelligence for either the fluid or the crystallised intelligence factor using the intelligence test Intelligenz-Struktur-Test (I-S-T 2000 R). Our data revealed significant correlations of the caudate nucleus and pallidum volumes with figural and numeric aspects of intelligence, but not with verbal intelligence. Interestingly, figural intelligence associations were dependent on sex and intelligence factor; in females, the pallidum volumes were correlated with crystallised figural intelligence (r = 0.372, p = 0.01), whereas in males, the caudate volumes were correlated with fluid figural intelligence (r = 0.507, p = 0.01). Numeric intelligence was correlated with right-lateralised caudate nucleus volumes for both females and males, but only for crystallised intelligence (r = 0.306, p = 0.04 and r = 0.459, p = 0.04, respectively). The associations were not mediated by prefrontal cortical subfield volumes when controlling with partial correlation analyses. The findings of our exploratory analysis indicate that figural and numeric intelligence aspects, but not verbal aspects, are strongly associated with basal ganglia volumes. Unlike numeric intelligence, the type of figural intelligence appears to be related to distinct basal ganglia nuclei in a sex-specific manner. Subcortical brain structures thus may contribute substantially to cognitive performance.

The effect of ageing on grey and white matter reductions in schizophrenia.

PubMed

Bose, Subrata K; Mackinnon, Toby; Mehta, Mitul A; Turkheimer, Federico E; Howes, Oliver D; Selvaraj, Sudhakar; Kempton, Matthew J; Grasby, Paul M

2009-07-01

Total brain volume and, in particular gray matter (GM) volume is reduced in patients with schizophrenia and recent studies suggest there is greater progressive loss of brain volume in the patients with schizophrenia than in normal controls. However, as the longitudinal studies do not include life-long follow-up, it is not clear if this occurs across the lifespan or only in the early phase of the illness. In this study we investigated this by studying the effects of age on brain tissue volumes in schizophrenia (n=34, age range=27-65 years)to test the prediction that there is a progressive loss in grey matter volume with increasing age in patients compared to healthy controls (n=33, age range=18-73 years). The results showed there was diminished relative GM volume loss with age in patients with schizophrenia compared to controls--in contrast to our prediction. However, there was increased relative white matter (WM) loss with age in schizophrenia. The results also replicated previous findings that patients with schizophrenia have significantly lower total (1509 versus 1596 mm(3)) and regional GM volume (755 versus 822 mm(3)) and increased cerebrospinal fluid (CSF) volume when compared to matched healthy volunteers. Overall these findings indicate that the proportion of grey matter in schizophrenia is reduced compared to controls early in the illness, and this difference diminishes with age; the corresponding effect in the proportion of WM is an increase with age compared to controls. This suggests that illness related factors may differentially affect grey and white matter, with implications for understanding the pathophysiology of schizophrenia and related psychotic disorders.

Fluids and diuretics for acute ureteric colic.

PubMed

Worster, Andrew S; Bhanich Supapol, Wendy

2012-02-15

Acute ureteric colic is commonly associated with severe and debilitating pain. Theoretically, increasing fluid flow through the affected kidney might expedite stone passage, thereby improving symptoms more quickly. The efficacy and safety of interventions such as high volume intravenous (IV) or oral fluids and diuretics aimed at expediting ureteric stone passage is, however, uncertain. To look at the benefits and harms of diuretics and high volume (above maintenance) IV or oral fluid therapy for treating adult patients presenting with uncomplicated acute ureteric colic. We searched the Cochrane Renal Group's specialised register (3 January 2012). Previously we searched the Cochrane Central Register of Controlled Trials (CENTRAL The Cochrane Library), MEDLINE (from 1966), EMBASE (from 1980) and handsearched reference lists of nephrology and urology textbooks, review articles, relevant studies, and abstracts from nephrology scientific meetings. All randomised controlled trials (RCTs) and quasi-RCTs (including the first period of randomised cross-over studies) looking at diuretics or high volume IV or oral fluids for treating uncomplicated acute ureteric colic in adult patients presenting to the emergency department for the first time during that episode were included. Two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random-effects model for multiple studies of the same outcomes, otherwise the fixed-effect model was used. Results were expressed as risk ratios (RR) for dichotomous outcomes or as mean differences (MD) for continuous data with 95% confidence intervals (CI). Two studies (enrolling 118 participants) examined the association between intense hydration and ureteric colic outcomes. There was no significant difference in pain at six hours (1 study, 60 participants: RR 1.06, 95% CI 0.71 to 1.57), surgical stone removal (1 study, 60 participants: RR 1.20, 95% CI 0.41 to 3.51) or manipulation by cystoscopy (1 study, 60 participants: RR 0.67, 95% CI 0.21 to 2.13) when no fluids over six hours was compared to three litres IV fluids administered over a six hour period. There was no difference in stone clearance (1 study 43 participants: RR 1.38, 95% CI 0.50 to 3.84), hourly pain score or patients' narcotic requirements (P > 0.05 for all comparisons) when forced IV hydration of two litres over four hours was compared with minimal IV hydration at 20 mL/hour.One study did not provide any details which would have allowed us to assess any of the risk of bias items (selection, detection, performance, attrition or reporting bias). The second study did not report the method of randomisation or allocation (selection bias - unclear), they reported that the patients were blinded to therapy (low risk of bias), analgesics were administered according to predetermined pain score criteria (low risk), and assessment of stone passage was unlikely to have been biased by knowledge of group assignment (low risk). However the second study also reported a high percentage of participants excluded post randomisation (26%; high risk of bias). We were unable to assess or ascertain any of the other risk of bias items. We found no reliable evidence in the literature to support the use of diuretics and high volume fluid therapy for people with acute ureteric colic. However, given the potential positive therapeutic impact of fluids and diuretics to facilitate stone passage, the capacity of these interventions warrants further investigation to determine safety and efficacy profiles.

Recombinant human hyaluronidase PH20 (rHuPH20) facilitates subcutaneous infusions of large volumes of immunoglobulin in a swine model.

PubMed

Kang, David W; Jadin, Laurence; Nekoroski, Tara; Drake, Fred H; Zepeda, Monica L

2012-08-01

Many patients with primary immunodeficiency disease (PIDD) require lifelong immunoglobulin (Ig) replacement therapy. Home-based subcutaneous (SC) infusion provides advantages to patients with PIDD compared to hospital-based intravenous infusion. One limitation of current practice with SCIg infusion is the need for small-volume infusions at multiple injection sites on a frequent basis. A method was developed for large-volume SC infusion that uses preinfusion of recombinant human hyaluronidase (rHuPH20) to facilitate fluid dispersion. Miniature swine was used as a preclinical model to assess the effects of rHuPH20-facilitated infusions, of a single monthly dose, on fluid dispersion, infusion-related pressure, swelling, induration, and tissue damage. Preinfusion of vehicle (control) or rHuPH20 (75 U/g Ig) was performed simultaneously on contralateral abdominal sites on each animal, followed by infusion of 300 mL 10 % Ig (30 g) at each site. Compared to control infusions, rHuPH20 significantly reduced infusion pressure and induration (p < 0.05) and accelerated postinfusion Ig dispersion. Histological evaluation of infusion site tissue showed moderate to severe swelling for the control. Swelling after rHuPH20-facilitated infusion was mild on day 1 and had completely resolved shortly thereafter. Laser Doppler imaging of control infusion sites revealed local cutaneous hypoperfusion during Ig infusion, which was reduced almost 7-fold (p < 0.05) with the use of rHuPH20. These results demonstrate that rHuPH20-facilitated Ig infusion is associated with improved dispersion of Ig, resulting in reduced tissue pressure, induration, and reduced risk of tissue damage from mechanical trauma or local ischemia, thus enabling SC administration of large volumes of Ig at a single site.

Effect of soda consumption on urinary stone risk parameters.

PubMed

Passman, Corey M; Holmes, Ross P; Knight, John; Easter, Linda; Pais, Vernon; Assimos, Dean G

2009-03-01

Fluid consumption has been demonstrated to influence kidney stone formation. Studies have shown that consumption of cola may be a risk factor for stone disease, while fluids containing citric acid may attenuate stone activity. Diet was not always controlled in these investigations, however. We undertook a study to determine the impact of three different fluids on urinary stone risk factors. Six healthy nonstone-forming adults were placed on a standardized metabolic diet and consumed three different types of fluid during three 5-day periods. There was a 2-day washout between each sequence. The three fluids administered during these periods were Le Bleu water, caffeine-free Diet Coke, and Fresca (citrate containing). These two soda preparations were chosen to prevent the known increase in calcium excretion promoted by carbohydrates and caffeine. Twenty-four hour urine specimens were collected on days 4 and 5 of each sequence. The following urinary parameters were measured: Volume, calcium, oxalate, creatinine, uric acid, citrate, sodium, magnesium, phosphorus, sulfate, urea nitrogen, pH, and supersaturation indices. A paired t test was used for statistical analysis. Urinary volumes were significantly higher and supersaturation of calcium oxalate significantly lower compared with a self-selected dietary regimen. A decrease in uric acid was also seen in the Fresca cohort. There were no statistically significant differences for any of the urinary parameters. There is no increased risk or benefit to consuming Fresca or caffeine-free Diet Coke compared with Le Bleu bottled water with respect to stone formation.

Automatic, accurate, and reproducible segmentation of the brain and cerebro-spinal fluid in T1-weighted volume MRI scans and its application to serial cerebral and intracranial volumetry

NASA Astrophysics Data System (ADS)

Lemieux, Louis

2001-07-01

A new fully automatic algorithm for the segmentation of the brain and cerebro-spinal fluid (CSF) from T1-weighted volume MRI scans of the head was specifically developed in the context of serial intra-cranial volumetry. The method is an extension of a previously published brain extraction algorithm. The brain mask is used as a basis for CSF segmentation based on morphological operations, automatic histogram analysis and thresholding. Brain segmentation is then obtained by iterative tracking of the brain-CSF interface. Grey matter (GM), white matter (WM) and CSF volumes are calculated based on a model of intensity probability distribution that includes partial volume effects. Accuracy was assessed using a digital phantom scan. Reproducibility was assessed by segmenting pairs of scans from 20 normal subjects scanned 8 months apart and 11 patients with epilepsy scanned 3.5 years apart. Segmentation accuracy as measured by overlap was 98% for the brain and 96% for the intra-cranial tissues. The volume errors were: total brain (TBV): -1.0%, intra-cranial (ICV):0.1%, CSF: +4.8%. For repeated scans, matching resulted in improved reproducibility. In the controls, the coefficient of reliability (CR) was 1.5% for the TVB and 1.0% for the ICV. In the patients, the Cr for the ICV was 1.2%.

A Microfluidic Approach for Studying Piezo Channels.

PubMed

Maneshi, M M; Gottlieb, P A; Hua, S Z

2017-01-01

Microfluidics is an interdisciplinary field intersecting many areas in engineering. Utilizing a combination of physics, chemistry, biology, and biotechnology, along with practical applications for designing devices that use low volumes of fluids to achieve high-throughput screening, is a major goal in microfluidics. Microfluidic approaches allow the study of cells growth and differentiation using a variety of conditions including control of fluid flow that generates shear stress. Recently, Piezo1 channels were shown to respond to fluid shear stress and are crucial for vascular development. This channel is ideal for studying fluid shear stress applied to cells using microfluidic devices. We have developed an approach that allows us to analyze the role of Piezo channels on any given cell and serves as a high-throughput screen for drug discovery. We show that this approach can provide detailed information about the inhibitors of Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

Poor ultrafiltration during nighttime dialysis in CAPD patients and its effects on fluid balance.

PubMed

Pagé, D E; Levine, D Z

1993-01-01

To evaluate fluid retention during the long nighttime peritoneal dwell in continuous ambulatory peritoneal dialysis (CAPD) patients, we measured remaining volumes in 70 patients. In only 50% of these patients were more than 2 L of fluid recovered; in 30% between 1.5 and 2 L were recovered; and in 17% of patients we retrieved less than 1.5 L of peritoneal fluid. In 3 of these patients, who were edematous and had marked pitting edema, we shortened the nighttime dwell by having the patients awaken after 4 hours and drain the dwell. This resulted in 3-5 kg of weight loss in each patient, when compared with each patient's previous use of long nighttime dwells. Finally, we propose in this report two automated methods whereby the period of nighttime dialysis can be controlled, while patients sleep, using a system of timer clamps.

Evaluation of stroke volume variation obtained by arterial pulse contour analysis to predict fluid responsiveness intraoperatively.

PubMed

Lahner, D; Kabon, B; Marschalek, C; Chiari, A; Pestel, G; Kaider, A; Fleischmann, E; Hetz, H

2009-09-01

Fluid management guided by oesophageal Doppler monitor has been reported to improve perioperative outcome. Stroke volume variation (SVV) is considered a reliable clinical predictor of fluid responsiveness. Consequently, the aim of the present trial was to evaluate the accuracy of SVV determined by arterial pulse contour (APCO) analysis, using the FloTrac/Vigileo system, to predict fluid responsiveness as measured by the oesophageal Doppler. Patients undergoing major abdominal surgery received intraoperative fluid management guided by oesophageal Doppler monitoring. Fluid boluses of 250 ml each were administered in case of a decrease in corrected flow time (FTc) to <350 ms. Patients were connected to a monitoring device, obtaining SVV by APCO. Haemodynamic variables were recorded before and after fluid bolus application. Fluid responsiveness was defined as an increase in stroke volume index >10%. The ability of SVV to predict fluid responsiveness was assessed by calculation of the area under the receiver operating characteristic (ROC) curve. Twenty patients received 67 fluid boluses. Fifty-two of the 67 fluid boluses administered resulted in fluid responsiveness. SVV achieved an area under the ROC curve of 0.512 [confidence interval (CI) 0.32-0.70]. A cut-off point for fluid responsiveness was found for SVV > or =8.5% (sensitivity: 77%; specificity: 43%; positive predictive value: 84%; and negative predictive value: 33%). This prospective, interventional observer-blinded study demonstrates that SVV obtained by APCO, using the FloTrac/Vigileo system, is not a reliable predictor of fluid responsiveness in the setting of major abdominal surgery.

A Numerical Study of Mesh Adaptivity in Multiphase Flows with Non-Newtonian Fluids

NASA Astrophysics Data System (ADS)

Percival, James; Pavlidis, Dimitrios; Xie, Zhihua; Alberini, Federico; Simmons, Mark; Pain, Christopher; Matar, Omar

2014-11-01

We present an investigation into the computational efficiency benefits of dynamic mesh adaptivity in the numerical simulation of transient multiphase fluid flow problems involving Non-Newtonian fluids. Such fluids appear in a range of industrial applications, from printing inks to toothpastes and introduce new challenges for mesh adaptivity due to the additional ``memory'' of viscoelastic fluids. Nevertheless, the multiscale nature of these flows implies huge potential benefits for a successful implementation. The study is performed using the open source package Fluidity, which couples an unstructured mesh control volume finite element solver for the multiphase Navier-Stokes equations to a dynamic anisotropic mesh adaptivity algorithm, based on estimated solution interpolation error criteria, and conservative mesh-to-mesh interpolation routine. The code is applied to problems involving rheologies ranging from simple Newtonian to shear-thinning to viscoelastic materials and verified against experimental data for various industrial and microfluidic flows. This work was undertaken as part of the EPSRC MEMPHIS programme grant EP/K003976/1.

Comparison of cardiac output optimization with an automated closed-loop goal-directed fluid therapy versus non standardized manual fluid administration during elective abdominal surgery: first prospective randomized controlled trial.

PubMed

Lilot, Marc; Bellon, Amandine; Gueugnon, Marine; Laplace, Marie-Christine; Baffeleuf, Bruno; Hacquard, Pauline; Barthomeuf, Felicie; Parent, Camille; Tran, Thomas; Soubirou, Jean-Luc; Robinson, Philip; Bouvet, Lionel; Vassal, Olivia; Lehot, Jean-Jacques; Piriou, Vincent

2018-01-27

An intraoperative automated closed-loop system for goal-directed fluid therapy has been successfully tested in silico, in vivo and in a clinical case-control matching. This trial compared intraoperative cardiac output (CO) in patients managed with this closed-loop system versus usual practice in an academic medical center. The closed-loop system was connected to a CO monitoring system and delivered automated colloid fluid boluses. Moderate to high-risk abdominal surgical patients were randomized either to the closed-loop or the manual group. Intraoperative final CO was the primary endpoint. Secondary endpoints were intraoperative overall mean cardiac index (CI), increase from initial to final CI, intraoperative fluid volume and postoperative outcomes. From January 2014 to November 2015, 46 patients were randomized. There was a lower initial CI (2.06 vs. 2.51 l min -1 m -2 , p = 0.042) in the closed-loop compared to the control group. No difference in final CO and in overall mean intraoperative CI was observed between groups. A significant relative increase from initial to final CI values was observed in the closed-loop but not the control group (+ 28.6%, p = 0.006 vs. + 1.2%, p = 0.843). No difference was found for intraoperative fluid management and postoperative outcomes between groups. There was no significant impact on the primary study endpoint, but this was found in a context of unexpected lower initial CI in the closed-loop group.Trial registry number ID-RCB/EudraCT: 2013-A00770-45. ClinicalTrials.gov Identifier NCT01950845, date of registration: 17 September 2013.

Characterization of blood drawn rapidly for use in blood volume expansion studies: An animal model for simulated weightlessness

NASA Technical Reports Server (NTRS)

Chenault, V. Michelle; Lynch, Colleen D.; Morris, Mariana; Clodfelter, Jill; Hutchins, Phillip M.

1990-01-01

It was demonstrated that up to 8ml of blood can be drawn from donar rats without significantly increasing volume and stress sensitive hormones, and thus can be used for volume expansion studies. Infusion of whole blood allows more physiological changes that can be seen with volume expansion by saline or other ionic solutions. The infusion of whole blood to induce hypervolemia may provide an improved model to study the fluid balance and control mechanisms operative in weightlessness. Blood samples were drawn as quickly as possible from femoral artery catheters chronically implanted in Sprague Dawley rats and analyzed for hematocrit, plasma sodium, potassium, osmolality, corticosterone, epinepherine, norepinephrine, and vasopressin. The levels were found to be comparable to those of normal rats.

Storage of H.sub.2 by absorption and/or mixture within a fluid medium

DOEpatents

Berry, Gene David; Aceves, Salvador Martin

2007-03-20

For the first time, a hydrogen storage method, apparatus and system having a fluid mixture is provided. At predetermined pressures and/or temperatures within a contained substantially fixed volume, the fluid mixture can store a high density of hydrogen molecules, wherein a predetermined phase of the fluid mixture is capable of being withdrawn from the substantially fixed volume for use as a vehicle fuel or energy storage having reduced and/or eliminated evaporative losses, especially where storage weight, vessel cost, vessel shape, safety, and energy efficiency are beneficial.

White Matter Hyperintensities and Hypobaric Exposure

PubMed Central

McGuire, Stephen A.; Sherman, Paul M.; Wijtenburg, S. Andrea; Rowland, Laura M.; Grogan, Patrick M.; Sladky, John H.; Robinson, Andrew Y.; Kochunov, Peter V.

2014-01-01

Objective Demonstrate that occupational exposure to nonhypoxic hypobaria is associated with subcortical white matter hyperintensities (WMHs) on fluid-attenuated inversion recovery magnetic resonance imaging (MRI). Methods Eighty-three altitude chamber personnel (PHY), 105 U-2 pilots (U2P), and 148 age- controlled and health-matched doctorate degree controls (DOC) underwent high-resolution MRI. Subcortical WMH burden was quantified as count and volume of subcortical WMH lesions after transformation of images to the Talairach atlas–based stereo-tactic frame. Results Subcortical WMHs were more prevalent in PHY (volume p = 0.011/count p = 0.019) and U2P (volume p<0.001/count p<0.001) when compared to DOC, whereas PHY were not significantly different than U2P. Interpretation This study provides strong evidence that nonhypoxic hypobaric exposure may induce subcortical WMHs in a young, healthy population lacking other risk factors for WMHs and adds this occupational exposure to other environmentally related potential causes of WMHs. PMID:25164539

Effect of a central redistribution of fluid volume on response to lower-body negative pressure

NASA Technical Reports Server (NTRS)

Tomaselli, Clare M.; Frey, Mary A. B.; Kenney, Richard A.; Hoffler, G. Wyckliffe

1990-01-01

Cardiovascular responses to lower-body negative pressure (LBNP) were studied following 1 hour of 6-deg head-down tilt to determine whether a redistribution of blood volume toward the central circulation modifies the subsequent response to orthostatic stress. Responses of 12 men, ages 30-39 years, were evaluated by electrocardiography, impedance cardiography, sphygmomanometry, and measurement of calf circumference. During the LBNP that followed head-down tilt, as compared with control LBNP (no preceding head-down tilt) subjects, had smaller stroke volume and cardiac output, greater total peripheral resistance, and less calf enlargement. These differences reflect differences in the variables immediately preceding LBNP. Magnitudes of the responses from pre-LBNP to each pressure stage of the LBNP procedure did not differ between protocols. Mean and diastolic arterial pressures were slightly elevated after LBNP-control, but they fell slightly during LBNP post-tilt.

HSD is a better resuscitation fluid for hemorrhagic shock with pulmonary edema at high altitude.

PubMed

Liu, Liang-Ming; Hu, De-Yao; Zhou, Xue-Wu; Liu, Jiang-Cang; Li, Ping

2008-12-01

To investigate the fluid tolerance of hemorrhagic shock with pulmonary edema (HSPE) at high altitude in unacclimated rats and the beneficial effect of 7.5% hypertonic saline/6% dextran (HSD). One hundred seventy-six Sprague-Dawley rats, transported to LaSa, Tibet, 3,760 m above the sea level, were anesthetized with sodium pentobarbital (30 mg/kg, i.p.) within 1 week. Hemorrhagic shock with pulmonary edema was induced by bloodletting (50 mmHg for 1 h) plus intravenous injection of oleic acid (50 microL/kg). Seventy-seven rats were equally divided into 11 groups (n = 7/group) including sham-operated control group; hemorrhagic shock control group; HSPE control group; HSPE plus 0.5-, 1.0-, 1.5-, 2.0-, or 3.0-fold volumes of lactated Ringer's solution (LR) groups; and HSPE plus 4, 6, and 8 mL/kg of HSD groups. Hemodynamic parameters including mean arterial blood pressure, left intraventricular systolic pressure, and the maximal change rate of intraventricular pressure rise or decline (+/-dp/dtmax) were observed at baseline and at 15, 30, 60, and 120 min after infusion; blood gases were measured at 30 and 120 min after infusion, and the water content of lung and brain was determined at 120 min after infusion. Additional 99 rats were used to observe the effect of these treatments on the survival time of HSPE rats; 0.5 volume of LR infusion slightly increased the mean arterial blood pressure, left intraventricular systolic pressure, and +/-dp/dtmax and prolonged the survival time of HSPE animals as compared with the HSPE group (P < 0.05 - 0.01); it did not increase the water content of lung and brain and had no marked influences on blood gases. One volume of LR infusion had somewhat improved the hemodynamic parameters for HSPE animals, but had no apparent effect on the survival time and the water content of lung and brain. Lactate Ringer's solution infusion, 1.5, 2, and 3 volumes, significantly deteriorated the hemodynamic parameters, increased the water content of lung, and decreased the survival time of HSPE animals. Hypertonic saline/6% dextran (4 - 8 mL/kg) significantly increased the hemodynamic parameters, improved the blood gases, decreased the water content of lung and brain, and prolonged the survival time of HSPE rats. Among the three dosages of HSD, 6 mL/kg of HSD had the best effect. The tolerance of fluid infusion for hemorrhagic shock with pulmonary edema at high altitude is significantly decreased. More than one volume of LR infusion would aggravate the pulmonary edema and exacerbate the resuscitation effect, but only one volume of LR cannot reach the effective volume resuscitation. Small volume of HSD could better resuscitate hemorrhagic shock with pulmonary edema at high altitude.

Rebound and jet formation of a fluid-filled sphere

NASA Astrophysics Data System (ADS)

Killian, Taylor W.; Klaus, Robert A.; Truscott, Tadd T.

2012-12-01

This study investigates the impact dynamics of hollow elastic spheres partially filled with fluid. Unlike an empty sphere, the internal fluid mitigates some of the rebound through an impulse driven exchange of energy wherein the fluid forms a jet inside the sphere. Surprisingly, this occurs on the second rebound or when the free surface is initially perturbed. Images gathered through experimentation show that the fluid reacts more quickly to the impact than the sphere, which decouples the two masses (fluid and sphere), imparts energy to the fluid, and removes rebound energy from the sphere. The experimental results are analyzed in terms of acceleration, momentum and an energy method suggesting an optimal fill volume in the neighborhood of 30%. While the characteristics of the fluid (i.e., density, viscosity, etc.) affect the fluid motion (i.e., type and size of jet formation), the rebound characteristics remain similar for a given fluid volume independent of fluid type. Implications of this work are a potential use of similar passive damping systems in sports technology and marine engineering.

Isoflurane in contrast to propofol promotes fluid extravasation during cardiopulmonary bypass in pigs.

PubMed

Brekke, Hege Kristin; Hammersborg, Stig Morten; Lundemoen, Steinar; Mongstad, Arve; Kvalheim, Venny Lise; Haugen, Oddbjørn; Husby, Paul

2013-10-01

A highly positive intraoperative fluid balance should be prevented as it negatively impacts patient outcome. Analysis of volume-kinetics has identified an increase in interstitial fluid volume after crystalloid fluid loading during isoflurane anesthesia. Isoflurane has also been associated with postoperative hypoxemia and may be associated with an increase in alveolar epithelial permeability, edema formation, and hindered oxygen exchange. In this article, the authors compare fluid extravasation rates before and during cardiopulmonary bypass (CPB) with isoflurane- versus propofol-based anesthesia. Fourteen pigs underwent 2 h of tepid CPB with propofol (P-group; n = 7) or isoflurane anesthesia (I-group; n = 7). Fluid requirements, plasma volume, colloid osmotic pressures in plasma and interstitial fluid, hematocrit levels, and total tissue water content were recorded, and fluid extravasation rates calculated. Fluid extravasation rates increased in the I-group from the pre-CPB level of 0.27 (0.13) to 0.92 (0.36) ml·kg·min, but remained essentially unchanged in the P-group with significant between-group differences during CPB (pb = 0.002). The results are supported by corresponding changes in interstitial colloid osmotic pressure and total tissue water content. During CPB, isoflurane, in contrast to propofol, significantly contributes to a general increase in fluid shifts from the intravascular to the interstitial space with edema formation and a possible negative impact on postoperative organ function.

Combination of microscopic model and VoF-multiphase approach for numerical simulation of nodular cast iron solidification

NASA Astrophysics Data System (ADS)

Subasic, E.; Huang, C.; Jakumeit, J.; Hediger, F.

2015-06-01

The ongoing increase in the size and capacity of state-of-the-art wind power plants is highlighting the need to reduce the weight of critical components, such as hubs, main shaft bearing housings, gear box housings and support bases. These components are manufactured as nodular iron castings (spheroid graphite iron, or SGI). A weight reduction of up to 20% is achievable by optimizing the geometry to minimize volume, thus enabling significant downsizing of wind power plants. One method for enhancing quality control in the production of thick-walled SGI castings, and thus reducing tolerances and, consequently, enabling castings of smaller volume is via a casting simulation of mould filling and solidification based on a combination of microscopic model and VoF-multiphase approach. Coupled fluid flow with heat transport and phase transformation kinetics during solidification is described by partial differential equations and solved using the finite volume method. The flow of multiple phases is described using a volume of fluid approach. Mass conservation equations are solved separately for both liquid and solid phases. At the micro-level, the diffusion-controlled growth model for grey iron eutectic grains by Wetterfall et al. is combined with a growth model for white iron eutectic grains. The micro-solidification model is coupled with macro-transport equations via source terms in the energy and continuity equations. As a first step the methodology was applied to a simple geometry to investigate the impact of mould-filling on the grey-to-white transition prediction in nodular cast iron.

Effect of Age-Related Human Lens Sutures Growth on Its Fluid Dynamics.

PubMed

Wu, Ho-Ting D; Howse, Louisa A; Vaghefi, Ehsan

2017-12-01

Age-related nuclear cataract is the opacification of the clear ocular lens due to oxidative damage as we age, and is the leading cause of blindness in the world. A lack of antioxidant supply to the core of ever-growing ocular lens could contribute to the cause of this condition. In this project, a computational model was developed to study the sutural fluid inflow of the aging human lens. Three different SOLIDWORKS computational fluid dynamics models of the human lens (7 years old; 28 years old; 46 years old) were created, based on available literature data. The fluid dynamics of the lens sutures were modelled using the Stokes flow equations, combined with realistic physiological boundary conditions and embedded in COMSOL Multiphysics. The flow rate, volume, and flow rate per volume of fluid entering the aging lens were examined, and all increased over the 40 years modelled. However, while the volume of the lens grew by ∼300% and the flow rate increased by ∼400%, the flow rate per volume increased only by very moderate ∼38%. Here, sutural information from humans of 7 to 46 years of age was obtained. In this modelled age range, an increase of flow rate per volume was observed, albeit at very slow rate. We hypothesize that with even further increasing age (60+ years old), the lens volume growth would outpace its flow rate increases, which would eventually lead to malnutrition of the lens nucleus and onset of cataracts.

Frequency spectrum analysis of finger photoplethysmographic waveform variability during haemodialysis.

PubMed

Javed, Faizan; Middleton, Paul M; Malouf, Philip; Chan, Gregory S H; Savkin, Andrey V; Lovell, Nigel H; Steel, Elizabeth; Mackie, James

2010-09-01

This study investigates the peripheral circulatory and autonomic response to volume withdrawal in haemodialysis based on spectral analysis of photoplethysmographic waveform variability (PPGV). Frequency spectrum analysis was performed on the baseline and pulse amplitude variabilities of the finger infrared photoplethysmographic (PPG) waveform and on heart rate variability extracted from the ECG signal collected from 18 kidney failure patients undergoing haemodialysis. Spectral powers were calculated from the low frequency (LF, 0.04-0.145 Hz) and high frequency (HF, 0.145-0.45 Hz) bands. In eight stable fluid overloaded patients (fluid removal of >2 L) not on alpha blockers, progressive reduction in relative blood volume during haemodialysis resulted in significant increase in LF and HF powers of PPG baseline and amplitude variability (P < 0.01), when expressed in mean-scaled units. The augmentation of LF powers in PPGV during haemodialysis may indicate the recovery and possibly further enhancement of peripheral sympathetic vascular modulation subsequent to volume unloading, whilst the increase in respiratory HF power in PPGV is most likely a sign of preload reduction. Spectral analysis of finger PPGV may provide valuable information on the autonomic vascular response to blood volume reduction in haemodialysis, and can be potentially utilized as a non-invasive tool for assessing peripheral circulatory control during routine dialysis procedure.

Method, system and computer program product for monitoring and optimizing fluid extraction from geologic strata

DOEpatents

Medizade, Masoud [San Luis Obispo, CA; Ridgely, John Robert [Los Osos, CA

2009-12-15

An arrangement which utilizes an inexpensive flap valve/flow transducer combination and a simple local supervisory control system to monitor and/or control the operation of a positive displacement pump used to extract petroleum from geologic strata. The local supervisory control system controls the operation of an electric motor which drives a reciprocating positive displacement pump so as to maximize the volume of petroleum extracted from the well per pump stroke while minimizing electricity usage and pump-off situations. By reducing the electrical demand and pump-off (i.e., "pounding" or "fluid pound") occurrences, operating and maintenance costs should be reduced sufficiently to allow petroleum recovery from marginally productive petroleum fields. The local supervisory control system includes one or more applications to at least collect flow signal data generated during operation of the positive displacement pump. No flow, low flow and flow duration are easily evaluated using the flap valve/flow transducer arrangement.

Conceptual Design Optimization of an Augmented Stability Aircraft Incorporating Dynamic Response and Actuator Constraints

NASA Technical Reports Server (NTRS)

Welstead, Jason; Crouse, Gilbert L., Jr.

2014-01-01

Empirical sizing guidelines such as tail volume coefficients have long been used in the early aircraft design phases for sizing stabilizers, resulting in conservatively stable aircraft. While successful, this results in increased empty weight, reduced performance, and greater procurement and operational cost relative to an aircraft with optimally sized surfaces. Including flight dynamics in the conceptual design process allows the design to move away from empirical methods while implementing modern control techniques. A challenge of flight dynamics and control is the numerous design variables, which are changing fluidly throughout the conceptual design process, required to evaluate the system response to some disturbance. This research focuses on addressing that challenge not by implementing higher order tools, such as computational fluid dynamics, but instead by linking the lower order tools typically used within the conceptual design process so each discipline feeds into the other. In thisresearch, flight dynamics and control was incorporated into the conceptual design process along with the traditional disciplines of vehicle sizing, weight estimation, aerodynamics, and performance. For the controller, a linear quadratic regulator structure with constant gains has been specified to reduce the user input. Coupling all the disciplines in the conceptual design phase allows the aircraft designer to explore larger design spaces where stabilizers are sized according to dynamic response constraints rather than historical static margin and volume coefficient guidelines.

Management of Gastric Obstruction Caused by Adjustable Gastric Band.

PubMed

Czeiger, David; Abu-Swis, Shadi; Shaked, Gad; Ovnat, Amnon; Sebbag, Gilbert

2016-12-01

Optimal adjustment of the filling volume of laparoscopic adjustable gastric banding is challenging and commonly performed empirically. Patients with band over-inflation and gastric obstruction arrive at the emergency department complaining of recurrent vomiting. In cases of gastric obstruction, intra-band pressure measurement may assist in determining the amount of fluid that should be removed from the band; however, our investigations have determined that intra-band pressure assessment need not play a role in the treatment of gastric band obstruction. In patients coming to the emergency department with gastric band obstruction, we measured intra-band pressure at arrival and following stepped removal of fluid, comparing the initial pressure with post-deflation pressure and measuring the volume of fluid removed. Forty-eight patients participated in the study. Forty-five patients had a low-pressure/high-volume band. Their mean baseline pressure was 54.6 ± 22.3 mmHg. The mean volume of fluid removed from the band was 1.3 ± 0.8 ml. The mean post-deflation pressure was 22.5 ± 16.3 mmHg. Nearly 30 % of patients required as little as 0.5 ml of fluid removal, and 60 % of them were free of symptoms with removal of 1 ml. Our results indicate that intra-band pressure measurement is of little value for determining the amount of fluid that should be removed for treatment of band obstruction. We suggest the removal of fluid in volumes of 0.5 ml until symptoms are relieved. Only in complicated cases, such as in patients having recurrent obstructions, should additional modalities be employed for further management guidance.

Evaluation of Dowfrost(TM) HD as a Thermal Control Fluid for Constellation Vehicles

NASA Technical Reports Server (NTRS)

Lee, Steve

2009-01-01

A test was conducted from November 2008 to January 2009 to help determine the compatibility of an inhibited propylene glycol/water solution with planned Constellation vehicles. Dowfrost(TradeMark) HD was selected as the baseline for Orion, as well as other Constellation systems. Therefore, the same Dowfrost(TradeMark) HD/Water solution planned for Orion was chosen for this test. The fluid was subjected to a thermal fluid loop that had flightlike properties, as compared to Orion. The fluid loop had similar wetted materials, temperatures, flow rates, and aluminum wetted surface area to fluid volume ratio. The test was designed to last for 10 years, the life expectancy of the lunar habitat. However, the test lasted less than two months. System filters became clogged with precipitate, rendering the fluid system inoperable. Upon examination of the precipitate, it was determined that the precipitate composition contained aluminum, which could have only come from materials in the test stand, as aluminum is not part of the Dowfrost(TradeMark HD composition. Also, the fluid pH was determined to have increased from 10.1, at the first test sample, to 12.2, at the completion of the test. This high of a pH is corrosive to aluminum and was certainly a contributing factor to the development of precipitate. Chemical analyses and bench-top tests are currently ongoing to determine the underlying cause for this rapid degradation of the fluid. Hamilton Sundstrand, the contractor developing the Orion thermal fluid loop, is performing a parallel effort to not only understand the cause of fluid degradation in the test, but also to investigate solutions to avoid this problem in the Orion s thermal control system. JSC also consulted with the Hamilton Sundstrand team in the development of this test and the subsequent analysis.

Characterization of fluid physics effects on cardiovascular response to microgravity (G-572)

NASA Technical Reports Server (NTRS)

Pantalos, George M.; Bennett, Thomas E.; Sharp, M. Keith; Woodruff, Stewart; Oleary, Sean; Gillars, Kevin; Lemon, Mark; Sojka, Jan

1995-01-01

The investigation of cardiovascular adaptation to space flight has seen substantial advancement in the last several years. In-flight echocardiographic measurements of astronaut cardiac function on the Space Shuttle have documented an initial increase, followed by a progressive reduction in both left ventricular volume index and stroke volume with a compensatory increase in heart rate to maintain cardiac output. To date, the reduced cardiac size and stroke volume have been presumed to be the consequence of the reduction in circulating fluid volume within a few days after orbital insertion. However, no specific mechanism for the reduced stroke volume has been identified. The following investigation proposes the use of a hydraulic model of the cardiovascular system to examine the possibility that the observed reduction in stroke volume may, in part, be related to fluid physics effects on heart function. The automated model is being prepared to fly as a Get Away Special (GAS) payload within the next year.

Non-invasive method and apparatus for monitoring intracranial pressure and pressure volume index in humans

NASA Technical Reports Server (NTRS)

Cantrell, John H. (Inventor); Yost, William T. (Inventor)

1994-01-01

Non-invasive measuring devices responsive to changes in a patient's intracranial pressure (ICP) can be accurately calibrated for monitoring purposes by providing known changes in ICP by non-invasive methods, such as placing the patient on a tilting bed and calculating a change in ICP from the tilt angle and the length of the patient's cerebrospinal column, or by placing a pressurized skull cap on the patient and measuring the inflation pressure. Absolute values for the patient's pressure-volume index (PVI) and the steady state ICP can then be determined by inducing two known changes in the volume of cerebrospinal fluid while recording the corresponding changes in ICP by means of the calibrated measuring device. The two pairs of data for pressure change and volume change are entered into an equation developed from an equation describing the relationship between ICP and cerebrospinal fluid volume. PVI and steady state ICP are then determined by solving the equation. Methods for inducing known changes in cerebrospinal fluid volume are described.

Non-invasive method and apparatus for monitoring intracranial pressure and pressure volume index in humans

NASA Technical Reports Server (NTRS)

Yost, William T. (Inventor); Cantrell, Jr., John H. (Inventor)

1997-01-01

Non-invasive measuring devices responsive to changes in a patient's intracranial pressure (ICP) can be accurately calibrated for monitoring purposes by providing known changes in ICP by non-invasive methods, such as placing the patient on a tilting bed and calculating a change in ICP from the tilt angle and the length of the patient's cerebrospinal column, or by placing a pressurized skull cap on the patient and measuring the inflation pressure. Absolute values for the patient's pressure-volume index (PVI) and the steady state ICP can then be determined by inducing two known changes in the volume of cerebrospinal fluid while recording the corresponding changes in ICP by means of the calibrated measuring device. The two pairs of data for pressure change and volume change are entered into an equation developed from an equation describing the relationship between ICP and cerebrospinal fluid volume. PVI and steady state ICP are then determined by solving the equation. Methods for inducing known changes in cerebrospinal fluid volume are described.

Quality assessment of reservoirs by means of outcrop data and "discrete fracture network" models: The case history of Rosario de La Frontera (NW Argentina) geothermal system

NASA Astrophysics Data System (ADS)

Maffucci, R.; Bigi, S.; Corrado, S.; Chiodi, A.; Di Paolo, L.; Giordano, G.; Invernizzi, C.

2015-04-01

We report the results of a systematic study carried out on the fracture systems exposed in the Sierra de La Candelaria anticline, in the central Andean retrowedge of northwestern Argentina. The aim was to elaborate a kinematic model of the anticline and to assess the dimensional and spatial properties of the fracture network characterizing the Cretaceous sandstone reservoir of the geothermal system of Rosario de La Frontera. Special regard was devoted to explore how tectonics may affect fluid circulation at depth and control fluids' natural upwelling at surface. With this aim we performed a Discrete Fracture Network model in order to evaluate the potential of the reservoir of the studied geothermal system. The results show that the Sierra de La Candelaria regional anticline developed according to a kinematic model of transpressional inversion compatible with the latest Andean regional WNW-ESE shortening, acting on a pre-orogenic N-S normal fault. A push-up geometry developed during positive inversion controlling the development of two minor anticlines: Termas and Balboa, separated by further NNW-SSE oblique-slip fault in the northern sector of the regional anticline. Brittle deformation recorded at the outcrop scale is robustly consistent with the extensional and transpressional events recognized at regional scale. In terms of fluid circulation, the NNW-SSE and NE-SW fault planes, associated to the late stage of the positive inversion, are considered the main structures controlling the migration paths of hot fluids from the reservoir to the surface. The results of the fracture modeling performed show that fractures related to the same deformation stage, are characterized by the highest values of secondary permeability. Moreover, the DFN models performed in the reservoir volume indicates that fracture network enhances its permeability: its secondary permeability is of about 49 mD and its fractured portion represents the 0.03% of the total volume.

Albumin extravasation and tissue washout of hyaluronan after plasma volume expansion with crystalloid or hypooncotic colloid solutions.

PubMed

Berg, S; Golster, M; Lisander, B

2002-02-01

Intravascular volume expansion is followed by loss of fluid from the circulation. The extravasation of albumin in this readjustment is insufficiently known. Twelve male volunteers participated, each in three separate sessions, in a controlled, randomised, open fashion. They received one of the following: albumin 40 g/L,(7.1 mL/kg, i.e. 500 mL per 70 kg); Ringer's acetate (21.4 mL/kg), or dextran 30 g/L (7.1 mL/kg). The fluids were infused during 30 min and the subjects were followed for 180 min. ECG, arterial oxygen saturation and non-invasive arterial pressure were recorded. Haemoglobin, haematocrit, serum albumin and osmolality, plasma colloid osmotic pressure and hyaluronan concentration were determined in venous samples. The serum albumin concentration decreased (P < 0.05, anova) following Ringer's acetate or dextran, whereas serum osmolality was unchanged in all groups. The colloid osmotic pressure decreased (P < 0.05) after the Ringer solution. The blood volume increase was estimated from the decrease in haemoglobin concentration and did not differ between the three fluids. The cumulated extravasation of albumin was largest following albumin (10.4 +/- 5.4 g, mean +/- SD), less following dextran (5.6 +/- 5.0 g) and negligible in the Ringer group (0.5 +/- 10.0 g; P < 0.05 against albumin). However, the Ringer solution increased the plasma concentration of hyaluronan drastically. Infusion of hypotonic colloidal solutions entails net loss of albumin from the vascular space. This is not the case after Ringer's acetate. Increased interstitial hydration from the latter fluid is followed by lymphatic wash out of hyaluronan.

[State of the art in fluid and volume therapy : A user-friendly staged concept].

PubMed

Rehm, M; Hulde, N; Kammerer, T; Meidert, A S; Hofmann-Kiefer, K

2017-03-01

Adequate fluid therapy is highly important for the perioperative outcome of our patients. Both, hypovolemia and hypervolemia can lead to an increase in perioperative complications and can impair the outcome. Therefore, perioperative infusion therapy should be target-oriented. The main target is to maintain the patient's preoperative normovolemia by using a sophisticated, rational infusion strategy.Perioperative fluid losses should be discriminated from volume losses (surgical blood loss or interstitial volume losses containing protein). Fluid losses as urine or perspiratio insensibilis (0.5-1.0 ml/kg/h) should be replaced by balanced crystalloids in a ratio of 1:1. Volume therapy step 1: Blood loss up to a maximum value of 20% of the patient's blood volume should be replaced by balanced crystalloids in a ratio of 4(-5):1. Volume therapy step 2: Higher blood losses should be treated by using iso-oncotic, preferential balanced colloids in a ratio of 1:1. For this purpose hydroxyethyl starch can also be used perioperatively if there is no respective contraindication, such as sepsis, burn injuries, critically ill patients, renal impairment or renal replacement therapy, and severe coagulopathy. Volume therapy step 3: If there is an indication for red cell concentrates or coagulation factors, a differentiated application of blood and blood products should be performed.

Analytical Assessment of a Gross Leakage Event Within the International Space Station (ISS) Node 2 Internal Active Thermal Control System (IATCS)

NASA Technical Reports Server (NTRS)

Holt, James M.; Clanton, Stephen E.

1999-01-01

Results of the International Space Station (ISS) Node 2 Internal Active Thermal Control System (IATCS) gross leakage analysis are presented for evaluating total leakage flowrates and volume discharge caused by a gross leakage event (i.e. open boundary condition). A Systems Improved Numerical Differencing Analyzer and Fluid Integrator (SINDA/FLUINT) thermal hydraulic mathematical model (THMM) representing the Node 2 IATCS was developed to simulate system performance under steady-state nominal conditions as well as the transient flow effects resulting from an open line exposed to ambient. The objective of the analysis was to determine the adequacy of the leak detection software in limiting the quantity of fluid lost during a gross leakage event to within an acceptable level.

Analytical Assessment of a Gross Leakage Event Within the International Space Station (ISS) Node 2 Internal Active Thermal Control System (IATCS)

NASA Technical Reports Server (NTRS)

Holt, James M.; Clanton, Stephen E.

2001-01-01

Results of the International Space Station (ISS) Node 2 Internal Active Thermal Control System (IATCS) gross leakage analysis are presented for evaluating total leakage flow rates and volume discharge caused by a gross leakage event (i.e. open boundary condition). A Systems Improved Numerical Differencing Analyzer and Fluid Integrator (SINDA85/FLUINT) thermal hydraulic mathematical model (THMM) representing the Node 2 IATCS was developed to simulate system performance under steady-state nominal conditions as well as the transient flow effect resulting from an open line exposed to ambient. The objective of the analysis was to determine the adequacy of the leak detection software in limiting the quantity of fluid lost during a gross leakage event to within an acceptable level.

Capillary Imbibition of Hydraulic Fracturing Fluids into Partially Saturated Shale

NASA Astrophysics Data System (ADS)

Birdsell, D.; Rajaram, H.; Lackey, G.

2015-12-01

Understanding the migration of hydraulic fracturing fluids injected into unconventional reservoirs is important to assess the risk of aquifer contamination and to optimize oil and gas production. Capillary imbibition causes fracturing fluids to flow from fractures into the rock matrix where the fluids are sequestered for geologically long periods of time. Imbibition could explain the low amount of flowback water observed in the field (5-50% of the injected volume) and reduce the chance of fracturing fluid migrating out of formation towards overlying aquifers. We present calculations of spontaneous capillary imbibition in the form of an "imbibition rate parameter" (A) based on the only known exact analytical solution for spontaneous capillary imbibition. A depends on the hydraulic and capillary properties of the reservoir rock, the initial water saturation, and the viscosities of the wetting and nonwetting fluids. Imbibed volumes can be large for a high permeability shale gas reservoir (up to 95% of the injected volume) or quite small for a low permeability shale oil reservoir (as low as 3% of the injected volume). We also present a nondimensionalization of the imbibition rate parameter, which facilitates the calculation of A and clarifies the relation of A to initial saturation, porous medium properties, and fluid properties. Over the range of initial water saturations reported for the Marcellus shale (0.05-0.6), A varies by less than factors of ~1.8 and ~3.4 for gas and oil nonwetting phases respectively. However, A decreases significantly for larger initial water saturations. A is most sensitive to the intrinsic permeability of the reservoir rock and the viscosity of the fluids.

Simultaneous Determination of Fluid Shifts during Thermal Stress in a Small Animal Model,

DTIC Science & Technology

1985-09-01

extracellular fluid voitmie (BCF) was measured using a single injection c- inulin , technique, and plasma voilme (PV) was determined by ca.rdio--yreen dye...using tritiated water, extracell1ular fluid volume (ECF) was measured using a single injection C- inulin technique, and plasma volume (PV) was...space. However, inulin (10) has several advantages over the aforementioned because it Is not metabolized, stored, or incorporated by cells or

Analysis of head-down tilt as an analog of weightlessness using a methematical simulation model

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1984-01-01

Antiorthostasis or head down tilt of a moderate degree was used as a ground based analog of weightless space flight to study headward fluid shifts, decreased plasma volume, orthostatic intolerance and muscular skeletal degradation. A mathematical model was used to help interpret these observations. The model proved most valuable for these studies was originally developed as a description of the major circulatory, fluid and electrolyte control systems. Two different experimental studies are employed to validate the model. The first is a 24 hour head down tilt study and the second is a 7 day head down bed rest study. The major issues addressed include the reduction in plasma volume, the dynamic changes of venous pressure and cardiac output, the extent of central hypervolemia during long term zero g exposure, the existence of an early diuresis, the mechanisms which alter the renal regulating hormones during the short term and long term periods, the significance of potassium loss on other zero g responses, and the role of transcapillary filtration in adjusting fluid shifts. The use of mathematical models as an interpretive and analysis technique for experimental research for space life science is illustrated.

A Simple Apparatus for Demonstrating Fluid Forces and Newton's Third Law

NASA Astrophysics Data System (ADS)

Mohazzabi, Pirooz; James, Mark C.

2012-12-01

Over 2200 years ago, in order to determine the purity of a golden crown of the king of Syracuse, Archimedes submerged the crown in water and determined its volume by measuring the volume of the displaced water. This simple experiment became the foundation of what eventually became known as Archimedes' principle: An object fully or partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object. The principle is used to explain all questions regarding buoyancy, and the method is still prescribed for determination of the volume of irregularly shaped objects.2

Capacitance probe for fluid flow and volume measurements

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

1995-01-01

Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a microgravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

Capacitance Probe for Fluid Flow and Volume Measurements

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

1997-01-01

Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a micro-gravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

2013 AAHA/AAFP fluid therapy guidelines for dogs and cats.

PubMed

Davis, Harold; Jensen, Tracey; Johnson, Anthony; Knowles, Pamela; Meyer, Robert; Rucinsky, Renee; Shafford, Heidi

2013-01-01

Fluid therapy is important for many medical conditions in veterinary patients. The assessment of patient history, chief complaint, physical exam findings, and indicated additional testing will determine the need for fluid therapy. Fluid selection is dictated by the patient's needs, including volume, rate, fluid composition required, and location the fluid is needed (e.g., interstitial versus intravascular). Therapy must be individualized, tailored to each patient, and constantly re-evaluated and reformulated according to changes in status. Needs may vary according to the existence of either acute or chronic conditions, patient pathology (e.g., acid-base, oncotic, electrolyte abnormalities), and comorbid conditions. All patients should be assessed for three types of fluid disturbances: changes in volume, changes in content, and/or changes in distribution. The goals of these guidelines are to assist the clinician in prioritizing goals, selecting appropriate fluids and rates of administration, and assessing patient response to therapy. These guidelines provide recommendations for fluid administration for anesthetized patients and patients with fluid disturbances.

Intestinal fluid volumes and transit of dosage forms as assessed by magnetic resonance imaging.

PubMed

Schiller, C; Fröhlich, C-P; Giessmann, T; Siegmund, W; Mönnikes, H; Hosten, N; Weitschies, W

2005-11-15

The gastrointestinal transit of sequentially administered capsules was investigated in relation to the availability of fluid along the intestinal lumen by magnetic resonance imaging. Water-sensitive magnetic resonance imaging was performed on 12 healthy subjects during fasting and 1 h after a meal. Specifiable non-disintegrating capsules were administered at 7, 4 and 1 h prior to imaging. While food intake reduced the mean fluid volumes in the small intestine (105 +/- 72 mL vs. 54 +/- 41 mL, P < 0.01) it had no significant effect on the mean fluid volumes in the colon (13 +/- 12 mL vs. 18 +/- 26 mL). The mean number of separated fluid pockets increased in both organs after meal (small intestine: 4 vs. 6, P < 0.05; large intestine: 4 vs. 6, P < 0.05). The distribution of capsules between the small and large intestine was strongly influenced by food (colon: 3 vs. 17 capsules, P < 0.01). The results show that fluid is not homogeneously distributed along the gut, which likely contributes to the individual variability of drug absorption. Furthermore, transport of fluid and solids through the ileocaecal valve is obviously initiated by a meal-induced gastro-ileocaecal reflex.

Cerebral blood flow velocity and cranial fluid volume decrease during +Gz acceleration

NASA Technical Reports Server (NTRS)

Kawai, Y.; Puma, S. C.; Hargens, A. R.; Murthy, G.; Warkander, D.; Lundgren, C. E.

1997-01-01

Cerebral blood flow (CBF) velocity and cranial fluid volume, which is defined as the total volume of intra- and extracranial fluid, were measured using transcranial Doppler ultrasonography and rheoencephalography, respectively, in humans during graded increase of +Gz acceleration (onset rate: 0.1 G/s) without straining maneuvers. Gz acceleration was terminated when subjects' vision decreased to an angle of less than or equal to 60 degrees, which was defined as the physiological end point. In five subjects, mean CBF velocity decreased 48% from a baseline value of 59.4 +/- 11.2 cm/s to 31.0 +/- 5.6 cm/s (p<0.01) with initial loss of peripheral vision at 5.7 +/- 0.9 Gz. On the other hand, systolic CBF velocity did not change significantly during increasing +Gz acceleration. Cranial impedance, which is proportional to loss of cranial fluid volume, increased by 2.0 +/- 0.8% above the baseline value at the physiological end point (p<0.05). Both the decrease of CBF velocity and the increase of cranial impedance correlated significantly with Gz. These results suggest that +Gz acceleration without straining maneuvers decreases CBF velocity to half normal and probably causes a caudal fluid shift from both intra- and extracranial tissues.

Effect of hydration on interstitial distribution of charged albumin in rat dermis in vitro

PubMed Central

Wiig, Helge; Tenstad, Olav; Bert, Joel L

2005-01-01

At physiological pH, negatively charged glycosaminoglycans in the extracellular matrix may influence distribution volume of macromolecular probes, a phenomenon of importance for hydration of the interstitium and therefore for body fluid balance. We hypothesized that such charge effect was dependent on hydration. Human serum albumin (HSA) (the pH value for the isoelectric point (pI) = 4.9) was made neutral by cationization (cHSA) (pI = 7.6). Rat dermis was studied in vitro in a specially designed equilibration cell allowing control of hydration. Using a buffer containing labelled native HSA and cHSA, the distribution volumes were calculated relative to that of 51Cr-EDTA, an extracellular tracer. During changes in hydration (H), defined as (wet weight – dry weight) (dry weight)−1), the slope of the equation describing the relationship between extracellular fluid volume (Vx) (in g H2O (g dry weight)−1) and H (Vx = 0.925 H + 0.105) differed significantly from that for available volumes of cHSA (Va,cHSA = 0.624 H – 0.538) and HSA (Va,HSA = 0.518 H – 0.518). A gradual reduction in H led to a reduction in difference between available volumes for the two albumin species. Screening the fixed charges by 1 m NaCl resulted in similar available and excluded volumes of native HSA and neutral cHSA. We conclude that during gradual dehydration, there is a reduced effect of fixed negative charges on interstitial exclusion of charged macromolecules. This effect may be explained by a reduced hydration domain surrounding tissue and probe macromolecules in conditions of increased electrostatic interactions. Furthermore, screening of negative charges suggested that hyaluronan associated with collagen may influence intrafibrillar volume of collagen and thereby available and excluded volume fraction. PMID:16210353

The HYSLAR trial: a prospective randomized controlled trial of the use of a restrictive fluid regimen with 3% hypertonic saline versus lactated Ringers in patients undergoing pancreaticoduodenectomy.

PubMed

Lavu, Harish; Sell, Naomi M; Carter, Timothy I; Winter, Jordan M; Maguire, David P; Gratch, David M; Berman, Richard A; Feil, Marian G; Grunwald, Zvi; Leiby, Benjamin E; Pequignot, Edward C; Rosato, Ernest L; Yeo, Charles J

2014-09-01

This study was designed to determine whether the volume and type of fluid administered for pancreaticoduodenectomy impacts postoperative outcomes. Three percent hypertonic saline (HYS) has been suggested as a means of reducing the volume of fluid required to sustain tissue perfusion in the perioperative period. Between May 2011 and November 2013, patients undergoing pancreaticoduodenectomy were enrolled in an institutional review board-approved, single-center, prospective, parallel, randomized controlled trial (NCT 01428050), comparing lactated Ringers (LAR) (15 mL/kg/hr LAR intraoperation, 2 mL/kg/hr LAR postoperation) with HYS (9 mL/kg/hr LAR and 1 mL/kg/hr HYS intraoperation, 1 mL/kg/hr HYS postoperation). A total of 264 patients were randomized. Demographic variables between groups were similar. The HYS patients had a significantly reduced net fluid balance (65 vs 91 mL/kg, P = 0.02). The overall complication rate was reduced in the HYS group (43% vs 54%), with a relative risk of 0.79 [95% confidence interval (CI), 0.62-1.02; P = 0.073], factoring stratification for pancreas texture. After adjustment for age and weight, the relative risk was 0.75 [95% CI (0.58-0.96); P = 0.023]. The total number of complications was significantly reduced in the HYS group (93 vs 123), with an incidence rate ratio of 0.74 [95% CI (0.56-0.97); P = 0.027]. After adjustment for age and weight, the incidence rate ratio was 0.69 [95% CI (0.52-0.90); P = 0.0068]. Reoperations, length of stay, readmissions, and 90-day mortality were similar between groups. A moderately restrictive fluid regimen with HYS resulted in a statistically significant 25% reduction in complications when adjusted for age, weight, and pancreatic texture.

Coupled discrete element and finite volume solution of two classical soil mechanics problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Feng; Drumm, Eric; Guiochon, Georges A

One dimensional solutions for the classic critical upward seepage gradient/quick condition and the time rate of consolidation problems are obtained using coupled routines for the finite volume method (FVM) and discrete element method (DEM), and the results compared with the analytical solutions. The two phase flow in a system composed of fluid and solid is simulated with the fluid phase modeled by solving the averaged Navier-Stokes equation using the FVM and the solid phase is modeled using the DEM. A framework is described for the coupling of two open source computer codes: YADE-OpenDEM for the discrete element method and OpenFOAMmore » for the computational fluid dynamics. The particle-fluid interaction is quantified using a semi-empirical relationship proposed by Ergun [12]. The two classical verification problems are used to explore issues encountered when using coupled flow DEM codes, namely, the appropriate time step size for both the fluid and mechanical solution processes, the choice of the viscous damping coefficient, and the number of solid particles per finite fluid volume.« less

Accuracy of stroke volume variation in predicting fluid responsiveness: a systematic review and meta-analysis.

PubMed

Zhang, Zhongheng; Lu, Baolong; Sheng, Xiaoyan; Jin, Ni

2011-12-01

Stroke volume variation (SVV) appears to be a good predictor of fluid responsiveness in critically ill patients. However, a wide range of its predictive values has been reported in recent years. We therefore undertook a systematic review and meta-analysis of clinical trials that investigated the diagnostic value of SVV in predicting fluid responsiveness. Clinical investigations were identified from several sources, including MEDLINE, EMBASE, WANFANG, and CENTRAL. Original articles investigating the diagnostic value of SVV in predicting fluid responsiveness were considered to be eligible. Participants included critically ill patients in the intensive care unit (ICU) or operating room (OR) who require hemodynamic monitoring. A total of 568 patients from 23 studies were included in our final analysis. Baseline SVV was correlated to fluid responsiveness with a pooled correlation coefficient of 0.718. Across all settings, we found a diagnostic odds ratio of 18.4 for SVV to predict fluid responsiveness at a sensitivity of 0.81 and specificity of 0.80. The SVV was of diagnostic value for fluid responsiveness in OR or ICU patients monitored with the PiCCO or the FloTrac/Vigileo system, and in patients ventilated with tidal volume greater than 8 ml/kg. SVV is of diagnostic value in predicting fluid responsiveness in various settings.

The endocrine system in space flight

NASA Astrophysics Data System (ADS)

Leach, C. S.; Johnson, P. C.; Cintron, N. M.

Hormones are important effectors of the body's response to microgravity in the areas of fluid and electrolyte metabolism, erythropoiesis, and calcium metabolism. For many years antidiuretic hormone, cortisol and aldosterone have been considered the hormones most important for regulation of body fluid volume and blood levels of electrolytes, but they cannot account totally for losses of fluid and electrolytes during space flight. We have now measured atrial natriuretic factor (ANF), a hormone recently shown to regulate sodium and water excretion, in blood specimens obtained during flight. After 30 or 42 h of weightlessness, mean ANF was elevated. After 175 or 180 h, ANF had decreased by 59%, and it changed little between that time and soon after landing. There is probably an increase in ANF early inflight associated with the fluid shift, followed by a compensatory decrease in blood volume. Increased renal blood flow may cause the later ANF decrease. Erythropoietin (Ep), a hormone involved in the control of red blood cell production, was measured in blood samples taken during the first Spacelab mission and was significantly decreased on the second day of flight, suggesting also an increase in renal blood flow. Spacelab-2 investigators report that the active vitamin D metabolite 1α, 25-dihydroxyvitamin D 3 increased early in the flight, indicating that a stimulus for increased bone resorption occurs by 30 h after launch.

Substantia Nigra Volume Loss Before Basal Forebrain Degeneration in Early Parkinson Disease

PubMed Central

Ziegler, David A.; Wonderlick, Julien S.; Ashourian, Paymon; Hansen, Leslie A.; Young, Jeremy C.; Murphy, Alex J.; Koppuzha, Cecily K.; Growdon, John H.; Corkin, Suzanne

2017-01-01

Objective To test the hypothesis that degeneration of the substantia nigra pars compacta (SNc) precedes that of the cholinergic basal forebrain (BF) in Parkinson disease (PD) using new multispectral structural magnetic resonance (MR) imaging tools to measure the volumes of the SNc and BF. Design Matched case-control study. Setting The Athinoula A. Martinos Imaging Center at the McGovern Institute for Brain Research, Massachusetts Institute of Technology (MIT), and the Massachusetts General Hospital/MIT Morris Udall Center of Excellence in Parkinson Disease Research. Patients Participants included 29 patients with PD (Hoehn and Yahr [H&Y] stages 1–3) and 27 matched healthy control subjects. Main Outcome Measures We acquired multiecho T1-weighted, multiecho proton density, T2-weighted, and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences from each participant. For the SNc, we created a weighted mean of the multiple echoes, yielding a single volume with a high ratio of contrast to noise. We visualized the BF using T2-weighted FLAIR images. For each participant, we manually labeled the 2 structures and calculated their volumes. Results Relative to the controls, 13 patients with H&Y stage 1 PD had significantly decreased SNc volumes. Sixteen patients with H&Y stage 2 or 3 PD showed little additional volume loss. In contrast, the BF volume loss occurred later in the disease, with a significant decrease apparent in patients having H&Y stage 2 or 3 PD compared with the controls and the patients having H&Y stage 1 PD. The latter group did not differ significantly from the controls. Conclusion Our results support the proposed neuropathological trajectory in PD and establish novel multispectral methods as MR imaging biomarkers for tracking the degeneration of the SNc and BF. PMID:23183921

Unmasking a sustained negative effect of SGLT2 inhibition on body fluid volume in the rat.

PubMed

Masuda, Takahiro; Watanabe, Yuko; Fukuda, Keiko; Watanabe, Minami; Onishi, Akira; Ohara, Ken; Imai, Toshimi; Koepsell, Hermann; Muto, Shigeaki; Vallon, Volker; Nagata, Daisuke

2018-05-23

The chronic intrinsic diuretic and natriuretic tone of sodium-glucose cotransporter 2 (SGLT2) inhibitors is incompletely understood, because their effect on body fluid volume (BFV) has not been fully evaluated and because they often increase food and fluid intake at the same time. Here we first compared the effect of the SGLT2 inhibitor ipragliflozin (Ipra, 0.01% in diet for 8 weeks) and vehicle (Veh) in Spontaneously Diabetic Torii rat, a non-obese type 2 diabetic model, and non-diabetic Sprague-Dawley rats. In non-diabetic rats, Ipra increased urinary excretion of Na+ (UNaV) and fluid (UV) associated with increased food and fluid intake. Diabetes increased these 4 parameters, but Ipra had no further effect; probably due to its antihyperglycemic effect, such that glucosuria and as a consequence food and fluid intake were unchanged. Fluid balance and BFV, determined by bioimpedance spectroscopy, were similar among the 4 groups. To study the impact of food and fluid intake, non-diabetic rats were treated for 7 days with Veh, Ipra or Ipra+pair-feeding+pair-drinking (Pair-Ipra). Pair-Ipra maintained a small increase in UV and UNaV versus Veh despite similar food and fluid intake. Pair-Ipra induced a negative fluid balance and decreased BFV, while Ipra or Veh had no significant effect compared with basal values. In conclusion, SGLT2 inhibition induces a sustained diuretic and natriuretic tone. Homeostatic mechanisms are activated to stabilize body fluid volume, including compensatory increases in fluid and food intake.

Conservative fluid management prevents age-associated ventilator induced mortality.

PubMed

Herbert, Joseph A; Valentine, Michael S; Saravanan, Nivi; Schneck, Matthew B; Pidaparti, Ramana; Fowler, Alpha A; Reynolds, Angela M; Heise, Rebecca L

2016-08-01

Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hospital mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. 2month old and 20month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4h with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. At 4h, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1h in advanced age HVT subjects. In 4h ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in older subjects. Our study demonstrates that conservative fluid alone can attenuate the age associated increase in ventilator associated mortality. Copyright © 2016 Elsevier Inc. All rights reserved.

Conservative Fluid Management Prevents Age-Associated Ventilator Induced Mortality

PubMed Central

Herbert, Joseph A.; Valentine, Michael S.; Saravanan, Nivi; Schneck, Matthew B.; Pidaparti, Ramana; Fowler, Alpha A.; Reynolds, Angela M.; Heise, Rebecca L.

2017-01-01

Background Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hosptial mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. Methods 2 month old and 20 month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4 hours with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. Results At 4hrs, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1hr in advanced age HVT subjects. In 4hr ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in older subjects. Conclusion Our study demonstrates that conservative fluid alone can attenuate the age associated increase in ventilator associated mortality. PMID:27188767

Mother's but not father's education predicts general fluid intelligence in emerging adulthood: Behavioral and neuroanatomical evidence.

PubMed

Kong, Feng; Chen, Zhencai; Xue, Song; Wang, Xu; Liu, Jia

2015-11-01

Lower parental education impairs cognitive abilities of their offspring such as general fluid intelligence dependent on the prefrontal cortex (PFC), but the independent contribution of mother's and father's education is unknown. We used an individual difference approach to test whether mother's and father's education independently affected general fluid intelligence in emerging adulthood at both the behavioral and neural level. Behaviorally, mother's but not father's education accounted for unique variance in general fluid intelligence in emerging adulthood (assessed by the Raven's advanced progressive matrices). Neurally, the whole-brain correlation analysis revealed that the regional gray matter volume (rGMV) in the medial PFC was related to both mother's education and general fluid intelligence but not father's education. Furthermore, after controlling for mother's education, the association between general fluid intelligence and the rGMV in medial PFC was no longer significant, indicating that mother's education plays an important role in influencing the structure of the medial PFC associated with general fluid intelligence. Taken together, our study provides the first behavioral and neural evidence that mother's education is a more important determinant of general cognitive ability in emerging adulthood than father's education. © 2015 Wiley Periodicals, Inc.

Guide to Technical Documents. Volume 2. January 1983 through December 1983

DTIC Science & Technology

1983-12-01

4) inclu- sion of the fluid-structural interaction. CR 80.023 Flue Gas Desulfurization at Navy Bases, Navy Energy Guidance...availability, costs, and operating performance of industrial-sized flue gas desulfurization (FGD) systems for coal-fired boilers was performed for...to close visual inspection. N-1658 Control Strategies for Reducing Heating, Ventilating, and Air Conditioning (HVAC) Energy Consumption in Single

Initial susceptibility and viscosity properties of low concentration ɛ-Fe3 N based magnetic fluid

NASA Astrophysics Data System (ADS)

Huang, Wei; Wu, Jianmin; Guo, Wei; Li, Rong; Cui, Liya

2007-03-01

In this paper, the initial susceptibility of ɛ-Fe3N magnetic fluid at volume concentrations in the range Φ = 0.0 ˜ 0.0446 are measured. Compared with the experimental initial susceptibility, the Langevin, Weiss and Onsager susceptibility were calculated using the data obtained from the low concentration ɛ-Fe3N magnetic fluid samples. The viscosity of the ɛ-Fe3N magnetic fluid at the same concentrations is measured. The result shows that, the initial susceptibility of the low concentration ɛ-Fe3N magnetic fluid is proportional to the concentration. A linear relationship between relative viscosity and the volume fraction is observed when the concentration Φ < 0.02.

Process for heating coal-oil slurries

DOEpatents

Braunlin, W.A.; Gorski, A.; Jaehnig, L.J.; Moskal, C.J.; Naylor, J.D.; Parimi, K.; Ward, J.V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec[sup [minus]1]. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72. 29 figs.

Process for heating coal-oil slurries

DOEpatents

Braunlin, Walter A.; Gorski, Alan; Jaehnig, Leo J.; Moskal, Clifford J.; Naylor, Joseph D.; Parimi, Krishnia; Ward, John V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec.sup. -1. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72.

Using a tracer technique to identify the extent of non-ideal flows in the continuous mixing of non-Newtonian fluids

NASA Astrophysics Data System (ADS)

Patel, D.; Ein-Mozaffari, F.; Mehrvar, M.

2013-05-01

The identification of non-ideal flows in a continuous-flow mixing of non-Newtonian fluids is a challenging task for various chemical industries: plastic manufacturing, water and wastewater treatment, and pulp and paper manufacturing. Non-ideal flows such as channelling, recirculation, and dead zones significantly affect the performance of continuous-flow mixing systems. Therefore, the main objective of this paper was to develop an identification protocol to measure non-ideal flows in the continuous-flow mixing system. The extent of non-ideal flows was quantified using a dynamic model that incorporated channelling, recirculation, and dead volume in the mixing vessel. To estimate the dynamic model parameters, the system was excited using a frequency-modulated random binary input by injecting the saline solution (as a tracer) into the fresh feed stream prior to being pumped into the mixing vessel. The injection of the tracer was controlled by a computer-controlled on-off solenoid valve. Using the trace technique, the extent of channelling and the effective mixed volume were successfully determined and used as mixing quality criteria. Such identification procedures can be applied at various areas of chemical engineering in order to improve the mixing quality.

Neuroanatomical correlates of Klinefelter syndrome studied in relation to the neuropsychological profile☆

PubMed Central

Skakkebæk, Anne; Gravholt, Claus Højbjerg; Rasmussen, Peter Mondrup; Bojesen, Anders; Jensen, Jens Søndergaard; Fedder, Jens; Laurberg, Peter; Hertz, Jens Michael; Østergaard, John Rosendahl; Pedersen, Anders Degn; Wallentin, Mikkel

2013-01-01

Brain imaging in Klinefelter syndrome (47, XXY) (KS), a genetic disorder characterized by the presence of an extra X chromosome, may contribute to understanding the relationship between gene expression, brain structure, and subsequent cognitive disabilities and psychiatric disorders. We conducted the largest to date voxel-based morphometry study of 65 KS subjects and 65 controls matched for age and education and correlated these data to neuropsychological test scores. The KS patients had significantly smaller total brain volume (TBV), total gray matter volume (GMV) and total white matter volume (WMV) compared to controls, whereas no volumetric difference in cerebral spinal fluid (CSF) was found. There were no differences in TBV, GMV, WMV or CSF between testosterone treated KS (T-KS) and untreated KS (U-KS) patients. Compared to controls, KS patients had significantly decreased GMV bilaterally in insula, putamen, caudate, hippocampus, amygdala, temporal pole and frontal inferior orbita. Additionally, the right parahippocampal region and cerebellar volumes were reduced in KS patients. KS patients had significantly larger volumes in right postcentral gyrus, precuneus and parietal regions. Multivariate classification analysis discriminated KS patients from controls with 96.9% (p < 0.001) accuracy. Regression analyses, however, revealed no significant association between GMV differences and cognitive and psychological factors within the KS patients and controls or the groups combined. These results show that although gene dosage effect of having and extra X-chromosome may lead to large scale alterations of brain morphometry and extended cognitive disabilities no simple correspondence links these measures. PMID:24266006

Neural mechanisms in body fluid homeostasis.

PubMed

DiBona, G F

1986-12-01

Under steady-state conditions, urinary sodium excretion matches dietary sodium intake. Because extracellular fluid osmolality is tightly regulated, the quantity of sodium in the extracellular fluid determines the volume of this compartment. The left atrial volume receptor mechanism is an example of a neural mechanism of volume regulation. The left atrial mechanoreceptor, which functions as a sensor in the low-pressure vascular system, is located in the left atrial wall, which has a well-defined compliance relating intravascular volume to filling pressure. The left atrial mechanoreceptor responds to changes in wall left atrial tension by discharging into afferent vagal fibers. These fibers have suitable central nervous system representation whose related efferent neurohumoral mechanisms regulate thirst, renal excretion of water and sodium, and redistribution of the extracellular fluid volume. Efferent renal sympathetic nerve activity undergoes appropriate changes to facilitate renal sodium excretion during sodium surfeit and to facilitate renal sodium conservation during sodium deficit. By interacting with other important determinants of renal sodium excretion (e.g., renal arterial pressure), changes in efferent renal sympathetic nerve activity can significantly modulate the final renal sodium excretion response with important consequences in pathophysiological states (e.g., hypertension, edema-forming states).

Stokesian swimming of a helical swimmer across an interface

NASA Astrophysics Data System (ADS)

Godinez, Francisco; Ramos, Armando; Zenit, Roberto

2016-11-01

Microorganisms swim in flows dominated by viscous effects but in many instances the motion occurs across heterogeneous environments where the fluid properties may vary. To our knowledge, the effect of such in-homogeneity has not been addressed in depth. We conduct experiments in which a magnetic self-propelled helical swimmer displaces across the interface between two immiscible density stratified fluids. As the swimmer crosses the interface, at a fixed rotation rate, its speed is reduced and a certain volume of the lower fluid is dragged across. We quantify the drift volume and the change of swimming speed for different swimming speeds and different fluid combinations. We relate the reduction of the swimming speed with the interfacial tension of the interface. We also compare the measurements of the drift volume with some recent calculations found in the literature.

Recovery after exercise in the heat--factors influencing fluid intake

NASA Technical Reports Server (NTRS)

Mack, G. W.

1998-01-01

The restoration of body fluid balance following dehydration induced by exercise will occur through regulatory responses which stimulate ingestion of water and sodium ions. A number of different afferent signalling systems are necessary to generate appropriate thirst or sodium appetite. The primary sensory information of naturally occurring thirst is derived from receptors sensing cell volume and the volume of the extracellular fluid compartment. Sensory information from the oropharyngeal region is also an important determinant of thirst. The interaction of these various afferent signalling systems within the central nervous system determines the extent of fluid replacement following dehydration.

Numerical simulation of bubble deformation in magnetic fluids by finite volume method

NASA Astrophysics Data System (ADS)

Yamasaki, Haruhiko; Yamaguchi, Hiroshi

2017-06-01

Bubble deformation in magnetic fluids under magnetic field is investigated numerically by an interface capturing method. The numerical method consists of a coupled level-set and VOF (Volume of Fluid) method, combined with conservation CIP (Constrained Interpolation Profile) method with the self-correcting procedure. In the present study considering actual physical properties of magnetic fluid, bubble deformation under given uniform magnetic field is analyzed for internal magnetic field passing through a magnetic gaseous and liquid phase interface. The numerical results explain the mechanism of bubble deformation under presence of given magnetic field.

The DC dielectric breakdown strength of magnetic fluids based on transformer oil

NASA Astrophysics Data System (ADS)

Kopčanský, Peter; Tomčo, Ladislav; Marton, Karol; Koneracká, Martina; Timko, Milan; Potočová, Ivana

2005-03-01

The DC dielectric breakdown strength of magnetic fluids based on transformer oil TECHNOL US 4000, with different saturation magnetizations, was investigated in various orientations of external magnetic field. It was shown that the dielectric breakdown strength in H∣∣ E is strongly influenced by the aggregation effects. As a boundary volume concentration of magnetic particles, below which the magnetic fluids have better dielectric properties than pure transformer oil, the volume concentration Φ=0.01 was found. Thus magnetic fluids with Φ<0.01 are suitable for the use as a high-voltage insulation.

Numerical Simulation of Two-Fluid Mingling Using the Particle Finite Element Method with Applications to Magmatic and Volcanic Processes

NASA Astrophysics Data System (ADS)

de Mier, M.; Costa, F.; Idelsohn, S.

2008-12-01

Many magmatic and volcanic processes (e.g., magma differentiation, mingling, transport in the volcanic conduit) are controlled by the physical properties and flow styles of high-temperature silicate melts. Such processes can be experimentally investigated using analog systems and scaling methods, but it is difficult to find the suitable material and it is generally not possible to quantitatively extrapolate the results to the natural system. An alternative means of studying fluid dynamics in volcanic systems is with numerical models. We have chosen the Particle Finite Element Method (PFEM), which is based on a Delaunay mesh that moves with the fluid velocity, the Navier-Stokes equations in Lagrangian formulation, and linear elements for velocity, pressure, and temperature. Remeshing is performed when the grid becomes too distorted [E. Oñate et al., 2004. The Particle Finite Element Method: An Overview. Int. J. Comput. Meth. 1, 267-307]. The method is ideal for tracking material interfaces between different fluids or media. Methods based on Eulerian reference frames need special techniques, such as level-set or volume-of-fluid, to capture the interface position, and these techniques add a significant numerical diffusion at the interface. We have performed a series of two-dimensional simulations of a classical problem of fluid dynamics in magmatic and volcanic systems: intrusion of a basaltic melt in a silica-rich magma reservoir. We have used realistic physical properties and equations of state for the silicate melts (e.g., temperature, viscosity, and density) and tracked the changes in the system for geologically relevant time scales (up to 100 years). The problem is modeled by the low-Mach-number equations derived from an asymptotic analysis of the compressible Navier-Stokes equations that removes shock waves from the flow but allows however large variations of density due to temperature variations. Non-constant viscosity and volume changes are taken into account in the momentum conservation equation through the full shear-stress tensor. The implications of different magma intrusion rates, volumes, and times will be discussed in the context of mafic-silicic magma mixing and eruption triggers.

Packaged peristaltic micropump for controlled drug delivery application

NASA Astrophysics Data System (ADS)

Vinayakumar, K. B.; Nadiger, Girish; R. Shetty, Vikas; Dinesh, N. S.; Nayak, M. M.; Rajanna, K.

2017-01-01

Micropump technology has evolved significantly in the last two decades and is finding a variety of applications ranging from μTAS (micro Total Analysis System) to drug delivery. However, the application area of the micropump is limited owing to: simple pumping mechanism, ease of handling, controlled (microliter to milliliter) delivery, continuous delivery, and accuracy in flow rate. Here, the author presents the design, development, characterization, and precision flow controlling of a DC-motor driven peristaltic pump for controlled drug delivery application. All the micropump components were fabricated using the conventional fabrication technique. The volume flow variation of the pump has been characterized for different viscous fluids. The change in volume flow due to change in back pressure has been presented in detail. The fail-safe mode operation of the pump has been tested and leak rate was measured (˜0.14% leak for an inlet pressure of 140 kPa) for different inlet pressures. The precision volume flow of the pump has been achieved by measuring the pinch cam position and load current. The accuracy in the volume flow has been measured after 300 rotations. Finally, the complete system has been integrated with the necessary electronics and an android application has been developed for the self-administration of bolus and basal delivery of insulin.

Increased Milk Protein Concentration in a Rehydration Drink Enhances Fluid Retention Caused by Water Reabsorption in Rats.

PubMed

Ito, Kentaro; Saito, Yuri; Ashida, Kinya; Yamaji, Taketo; Itoh, Hiroyuki; Oda, Munehiro

2015-01-01

A fluid-retention effect is required for beverages that are designed to prevent dehydration. That is, fluid absorbed from the intestines should not be excreted quickly; long-term retention is desirable. Here, we focused on the effect of milk protein on fluid retention, and propose a new effective oral rehydration method that can be used daily for preventing dehydration. We first evaluated the effects of different concentrations of milk protein on fluid retention by measuring the urinary volumes of rats fed fluid containing milk protein at concentrations of 1, 5, and 10%. We next compared the fluid-retention effect of milk protein-enriched drink (MPD) with those of distilled water (DW) and a sports drink (SD) by the same method. Third, to investigate the mechanism of fluid retention, we measured plasma insulin changes in rats after ingesting these three drinks. We found that the addition of milk protein at 5 or 10% reduced urinary volume in a dose-dependent manner. Ingestion of the MPD containing 4.6% milk protein resulted in lower urinary volumes than DW and SD. MPD also showed a higher water reabsorption rate in the kidneys and higher concentrations of plasma insulin than DW and SD. These results suggest that increasing milk protein concentration in a beverage enhances fluid retention, which may allow the possibility to develop rehydration beverages that are more effective than SDs. In addition, insulin-modifying renal water reabsorption may contribute to the fluid-retention effect of MPD.

Mingus Discontinuous Multiphysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pat Notz, Dan Turner

Mingus provides hybrid coupled local/non-local mechanics analysis capabilities that extend several traditional methods to applications with inherent discontinuities. Its primary features include adaptations of solid mechanics, fluid dynamics and digital image correlation that naturally accommodate dijointed data or irregular solution fields by assimilating a variety of discretizations (such as control volume finite elements, peridynamics and meshless control point clouds). The goal of this software is to provide an analysis framework form multiphysics engineering problems with an integrated image correlation capability that can be used for experimental validation and model

Fluid injection and induced seismicity

NASA Astrophysics Data System (ADS)

Kendall, Michael; Verdon, James

2016-04-01

The link between fluid injection, or extraction, and induced seismicity has been observed in reservoirs for many decades. In fact spatial mapping of low magnitude events is routinely used to estimate a stimulated reservoir volume. However, the link between subsurface fluid injection and larger felt seismicity is less clear and has attracted recent interest with a dramatic increase in earthquakes associated with the disposal of oilfield waste fluids. In a few cases, hydraulic fracturing has also been linked to induced seismicity. Much can be learned from past case-studies of induced seismicity so that we can better understand the risks posed. Here we examine 12 case examples and consider in particular controls on maximum event size, lateral event distributions, and event depths. Our results suggest that injection volume is a better control on maximum magnitude than past, natural seismicity in a region. This might, however, simply reflect the lack of baseline monitoring and/or long-term seismic records in certain regions. To address this in the UK, the British Geological Survey is leading the deployment of monitoring arrays in prospective shale gas areas in Lancashire and Yorkshire. In most cases, seismicity is generally located in close vicinity to the injection site. However, in some cases, the nearest events are up to 5km from the injection point. This gives an indication of the minimum radius of influence of such fluid injection projects. The most distant events are never more than 20km from the injection point, perhaps implying a maximum radius of influence. Some events are located in the target reservoir, but most occur below the injection depth. In fact, most events lie in the crystalline basement underlying the sedimentary rocks. This suggests that induced seismicity may not pose a leakage risk for fluid migration back to the surface, as it does not impact caprock integrity. A useful application for microseismic data is to try and forecast induced seismicity during injection, with the aim of mitigating large induced events before they happen. Microseismic event population statistics can be used to make forecasts about the future maximum event magnitude as the injection program continues. By making such forecasts, mitigating actions may be possible if forecast maximum magnitudes exceed a predefined limit.

Dynamic Deployment Simulations of Inflatable Space Structures

NASA Technical Reports Server (NTRS)

Wang, John T.

2005-01-01

The feasibility of using Control Volume (CV) method and the Arbitrary Lagrangian Eulerian (ALE) method in LSDYNA to simulate the dynamic deployment of inflatable space structures is investigated. The CV and ALE methods were used to predict the inflation deployments of three folded tube configurations. The CV method was found to be a simple and computationally efficient method that may be adequate for modeling slow inflation deployment sine the inertia of the inflation gas can be neglected. The ALE method was found to be very computationally intensive since it involves the solving of three conservative equations of fluid as well as dealing with complex fluid structure interactions.

Perioperative intravenous fluid prescribing: a multi-centre audit.

PubMed

Harris, Benjamin; Schopflin, Christian; Khaghani, Clare; Edwards, Mark

2015-01-01

Excessive or inadequate intravenous fluid given in the perioperative period can affect outcomes. A number of guidelines exist but these can conflict with the entrenched practice, evidence base and prescriber knowledge. We conducted a multi-centre audit of intraoperative and postoperative intravenous fluid therapy to investigate fluid administration practice and frequency of postoperative electrolyte disturbances. A retrospective audit was done in five hospitals of adult patients undergoing elective major abdominal, gastrointestinal tract or orthopaedic surgery. The type, volume and quantity of fluid and electrolytes administered during surgery and in 3 days postoperatively was calculated, and electrolyte disturbances were studied using clinical records. Data from four hundred thirty-one patients in five hospitals covering 1157 intravenous fluid days were collected. Balanced crystalloid solutions were almost universally used in the operating theatre and were also the most common fluid administered postoperatively, followed by hypotonic dextrose-saline solutions and 0.9 % sodium chloride. For three common uncomplicated elective operations, the volume of fluid administered intraoperatively demonstrated considerable variability. Over half of the patients received no postoperative fluid on day 1, and even more were commenced on free oral fluids immediately postoperatively or on day 1. Postoperative quantities of sodium exceeded the recommended amounts for maintenance in half of the patients who continued to receive intravenous fluids. Potassium administration in those receiving intravenous fluids was almost universally inadequate. Hypokalaemia and hyponatraemia were the common findings. We documented the current clinical practice and confirmed that early free oral fluids and cessation of any intravenous fluids is common postoperatively in keeping with the aims of enhanced recovery after surgery programmes. Excessive sodium and water and inadequate potassium in those given intravenous fluids postoperatively is common and needs to be investigated. The variation in intraoperative fluid volume administration for three common procedures is considerable and in keeping with other international studies. Future trials of fluid therapy should include the intraoperative and postoperative phases.

Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve

PubMed Central

Velescu, C.; Popa, N. C.

2015-01-01

We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids' motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance. PMID:26167532

Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve.

PubMed

Velescu, C; Popa, N C

2015-01-01

We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids' motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance.

Apparatus and method for collection and concentration of respirable particles into a small fluid volume

DOEpatents

Simon, Jonathan N.; Brown, Steve B.

2002-01-01

An apparatus and method for the collection of respirable particles and concentration of such particles into a small fluid volume. The apparatus captures and concentrates small (1-10 .mu.m) respirable particles into a sub-millileter volume of fluid. The method involves a two step operation, collection and concentration: wherein collection of particles is by a wetted surface having small vertical slits that act as capillary channels; and concentration is carried out by transfer of the collected particles to a small volume (sub-milliliter) container by centrifugal force whereby the particles are forced through the vertical slits and contact a non-wetted wall surface, and are deflected to the bottom where they are contained for analysis, such as a portable flow cytometer or a portable PCR DNA analysis system.

Male Mating Rate Is Constrained by Seminal Fluid Availability in Bedbugs, Cimex lectularius

PubMed Central

Reinhardt, Klaus; Naylor, Richard; Siva-Jothy, Michael T.

2011-01-01

Sexual selection, differences in reproductive success between individuals, continues beyond acquiring a mating partner and affects ejaculate size and composition (sperm competition). Sperm and seminal fluid have very different roles in sperm competition but both components encompass production costs for the male. Theoretical models predict that males should spend ejaculate components prudently and differently for sperm and seminal fluid but empirical evidence for independent variation of sperm number and seminal fluid volume is scarce. It is also largely unknown how sperm and seminal fluid variation affect future mating rate. In bedbugs we developed a protocol to examine the role of seminal fluids in ejaculate allocation and its effect on future male mating rate. Using age-related changes in sperm and seminal fluid volume we estimated the lowest capacity at which mating activity started. We then showed that sexually active males allocate 12% of their sperm and 19% of their seminal fluid volume per mating and predicted that males would be depleted of seminal fluid but not of sperm. We tested (and confirmed) this prediction empirically. Finally, the slightly faster replenishment of seminal fluid compared to sperm did not outweigh the faster decrease during mating. Our results suggest that male mating rate can be constrained by the availability of seminal fluids. Our protocol might be applicable to a range of other organisms. We discuss the idea that economic considerations in sexual conflict research might benefit from distinguishing between costs and benefits that are ejaculate dose-dependent and those that are frequency-dependent on the mating rate per se. PMID:21779378

Drinking 300 mL of clear fluid two hours before surgery has no effect on gastric fluid volume and pH in fasting and non-fasting obese patients.

PubMed

Maltby, J Roger; Pytka, Saul; Watson, Neil C; Cowan, Robert A McTaggart; Fick, Gordon H

2004-02-01

To determine whether, in obese [body mass index (BMI) > 30 kg.m(2)] patients, oral intake of 300 mL clear liquid two hours before elective surgery affects the volume and pH of gastric contents at induction of anesthesia. A single-blind, randomized study of 126 adult patients, age > or = 18 yr, ASA physical status I or II, BMI > 30 kg.m(2) who were scheduled for elective surgery under general anesthesia. Patients were excluded if they had diabetes mellitus, symptoms of gastroesophageal reflux, or had taken medication within 24 hr that affects gastric secretion, gastric fluid pH or gastric emptying. All patients fasted from midnight and were randomly assigned to fasting or fluid group. Two hours before their scheduled time of surgery, all patients drank 10 mL of water containing phenol red 50 mg. Those in the fluid group followed with 300 mL clear liquid of their choice. Immediately following induction of general anesthesia and tracheal intubation, gastric contents were aspirated through a multiorifice Salem sump tube. The fluid volume, pH and phenol red concentration were recorded. Median (range) values in fasting vs fluid groups were: gastric fluid volume 26 (3-107) mL vs 30 (3-187) mL, pH 1.78 (1.31-7.08) vs 1.77 (1.27-7.34) and phenol red retrieval 0.1 (0-30)% vs 0.2 (0-15)%. Differences between groups were not statistically significant. Obese patients without comorbid conditions should follow the same fasting guidelines as non-obese patients and be allowed to drink clear liquid until two hours before elective surgery, inasmuch as obesity per se is not considered a risk factor for pulmonary aspiration.

Effect of Soda Consumption on Urinary Stone Risk Parameters

PubMed Central

Holmes, Ross P.; Knight, John; Easter, Linda; Pais, Vernon; Assimos, Dean G.

2009-01-01

Abstract Background and Purpose Fluid consumption has been demonstrated to influence kidney stone formation. Studies have shown that consumption of cola may be a risk factor for stone disease, while fluids containing citric acid may attenuate stone activity. Diet was not always controlled in these investigations, however. We undertook a study to determine the impact of three different fluids on urinary stone risk factors. Subjects and Methods Six healthy nonstone-forming adults were placed on a standardized metabolic diet and consumed three different types of fluid during three 5-day periods. There was a 2-day washout between each sequence. The three fluids administered during these periods were Le Bleu® water, caffeine-free Diet Coke,® and Fresca® (citrate containing). These two soda preparations were chosen to prevent the known increase in calcium excretion promoted by carbohydrates and caffeine. Twenty-four hour urine specimens were collected on days 4 and 5 of each sequence. The following urinary parameters were measured: Volume, calcium, oxalate, creatinine, uric acid, citrate, sodium, magnesium, phosphorus, sulfate, urea nitrogen, pH, and supersaturation indices. A paired t test was used for statistical analysis. Results Urinary volumes were significantly higher and supersaturation of calcium oxalate significantly lower compared with a self-selected dietary regimen. A decrease in uric acid was also seen in the Fresca cohort. There were no statistically significant differences for any of the urinary parameters. Conclusion There is no increased risk or benefit to consuming Fresca or caffeine-free Diet Coke compared with Le Bleu bottled water with respect to stone formation. PMID:19275488

Errors in fluid therapy in medical wards.

PubMed

Mousavi, Maryam; Khalili, Hossein; Dashti-Khavidaki, Simin

2012-04-01

Intravenous fluid therapy remains an essential part of patients' care during hospitalization. There are only few studies that focused on fluid therapy in the hospitalized patients, and there is not any consensus statement about fluid therapy in patients who are hospitalized in medical wards. The aim of the present study was to assess intravenous fluid therapy status and related errors in the patients during the course of hospitalization in the infectious diseases wards of a referral teaching hospital. This study was conducted in the infectious diseases wards of Imam Khomeini Complex Hospital, Tehran, Iran. During a retrospective study, data related to intravenous fluid therapy were collected by two clinical pharmacists of infectious diseases from 2008 to 2010. Intravenous fluid therapy information including indication, type, volume and rate of fluid administration was recorded for each patient. An internal protocol for intravenous fluid therapy was designed based on literature review and available recommendations. The data related to patients' fluid therapy were compared with this protocol. The fluid therapy was considered appropriate if it was compatible with the protocol regarding indication of intravenous fluid therapy, type, electrolyte content and rate of fluid administration. Any mistake in the selection of fluid type, content, volume and rate of administration was considered as intravenous fluid therapy errors. Five hundred and ninety-six of medication errors were detected during the study period in the patients. Overall rate of fluid therapy errors was 1.3 numbers per patient during hospitalization. Errors in the rate of fluid administration (29.8%), incorrect fluid volume calculation (26.5%) and incorrect type of fluid selection (24.6%) were the most common types of errors. The patients' male sex, old age, baseline renal diseases, diabetes co-morbidity, and hospitalization due to endocarditis, HIV infection and sepsis are predisposing factors for the occurrence of fluid therapy errors in the patients. Our result showed that intravenous fluid therapy errors occurred commonly in the hospitalized patients especially in the medical wards. Improvement in knowledge and attention of health-care workers about these errors are essential for preventing of medication errors in aspect of fluid therapy.

The reliability of the physical examination to guide fluid therapy in adults with severe falciparum malaria: an observational study.

PubMed

Hanson, Josh; Lam, Sophia W K; Alam, Shamsul; Pattnaik, Rajyabardhan; Mahanta, Kishore C; Uddin Hasan, Mahatab; Mohanty, Sanjib; Mishra, Saroj; Cohen, Sophie; Day, Nicholas; White, Nicholas; Dondorp, Arjen

2013-10-01

Adults with severe malaria frequently require intravenous fluid therapy to restore their circulating volume. However, fluid must be delivered judiciously as both under- and over-hydration increase the risk of complications and, potentially, death. As most patients will be cared for in a resource-poor setting, management guidelines necessarily recommend that physical examination should guide fluid resuscitation. However, the reliability of this strategy is uncertain. To determine the ability of physical examination to identify hypovolaemia, volume responsiveness, and pulmonary oedema, clinical signs and invasive measures of volume status were collected independently during an observational study of 28 adults with severe malaria. The physical examination defined volume status poorly. Jugular venous pressure (JVP) did not correlate with intravascular volume as determined by global end diastolic volume index (GEDVI; r(s) = 0.07, p = 0.19), neither did dry mucous membranes (p = 0.85), or dry axillae (p = 0.09). GEDVI was actually higher in patients with decreased tissue turgor (p < 0.001). Poor capillary return correlated with GEDVI, but was present infrequently (7% of observations) and, therefore, insensitive. Mean arterial pressure (MAP) correlated with GEDVI (rs = 0.16, p = 0.002), but even before resuscitation patients with a low GEDVI had a preserved MAP. Anuria on admission was unrelated to GEDVI and although liberal fluid resuscitation led to a median hourly urine output of 100 ml in 19 patients who were not anuric on admission, four (21%) developed clinical pulmonary oedema subsequently. MAP was unrelated to volume responsiveness (p = 0.71), while a low JVP, dry mucous membranes, dry axillae, increased tissue turgor, prolonged capillary refill, and tachycardia all had a positive predictive value for volume responsiveness of ≤50%. Extravascular lung water ≥11 ml/kg indicating pulmonary oedema was present on 99 of the 353 times that it was assessed during the study, but was identified on less than half these occasions by tachypnoea, chest auscultation, or an elevated JVP. A clear chest on auscultation and a respiratory rate <30 breaths/minute could exclude pulmonary oedema on 82% and 72% of occasions respectively. Findings on physical examination correlate poorly with true volume status in adults with severe malaria and must be used with caution to guide fluid therapy. Clinicaltrials.gov identifier: NCT00692627.

A noninvasive method to study regulation of extracellular fluid volume in rats using nuclear magnetic resonance

EPA Pesticide Factsheets

NMR fluid measurements of commonly used rat strains when subjected to SQ normotonic or hypertonic salines, as well as physiologic comparisons to sedentary and exercised subjects.This dataset is associated with the following publication:Gordon , C., P. Phillips , and A. Johnstone. A Noninvasive Method to Study Regulation of Extracellular Fluid Volume in Rats Using Nuclear Magnetic Resonance. American Journal of Physiology- Renal Physiology. American Physiological Society, Bethesda, MD, USA, 310(5): 426-31, (2016).

Effects of hypertonic saline (7.5%) on extracellular fluid volumes compared with normal saline (0.9%) and 6% hydroxyethyl starch after aortocoronary bypass graft surgery.

PubMed

Järvelä, K; Koskinen, M; Kaukinen, S; Kööbi, T

2001-04-01

To compare the effects of hypertonic (7.5%) saline (HS), normal (0.9%) saline (NS), and 6% hydroxyethyl starch (HES) on extracellular fluid volumes in the early postoperative period after cardiopulmonary bypass. A prospective, randomized, double-blind study. University teaching hospital. Forty-eight patients scheduled for elective coronary artery bypass graft surgery. Patients were randomly allocated to receive 4 mL/kg of HS, NS, or HES during 30 minutes when volume loading was needed during the postoperative rewarming period in the intensive care unit. Plasma volume was measured using a dilution of iodine-125-labeled human serum albumin. Extracellular water and cardiac output were measured by whole-body impedance cardiography. Plasma volume had increased by 19 +/- 7% in the HS group and by 10 +/- 3% in the NS group (p = 0.001) at the end of the study fluid infusion. After 1-hour follow-up time, the plasma volume increase was greatest (23 +/- 8%) in the group receiving HES (p < 0.001). The increase of extracellular water was greater than the infused volume in the HS and HES groups at the end of the infusion. One-hour diuresis after the study infusion was greater in the HS group (536 +/- 280 mL) than in the NS (267 +/- 154 mL, p = 0.006) and HES groups (311 +/- 238 mL, p = 0.025). The effect of HS on plasma volume was short-lasting, but it stimulated excretion of excess body fluid accumulated during cardiopulmonary bypass and cardiac surgery. HS may be used in situations in which excess free water administration is to be avoided but the intravascular volume needs correction. Copyright 2001 by W.B. Saunders Company

The interstitial distribution of macromolecules in rat tumours is influenced by the negatively charged matrix components

PubMed Central

Wiig, Helge; Gyenge, Christina C; Tenstad, Olav

2005-01-01

Knowledge of macromolecular distribution volumes is essential in understanding fluid transport within normal and pathological tissues. In this study in vivo we determined the distribution volumes of several macromolecules, including one monoclonal antibody, in tumours and tested whether charges associated with the tumour extracellular matrix influence their available volumes. Steady state levels of the monoclonal antibody trastuzumab (Herceptin) (pI = 9.2), IgG (pI = 7.6) as well as native (pI = 5.0) and cationized albumin (pI = 7.6) were established in rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours by continuous infusion using osmotic minipumps. After a 5–7 day infusion period, the rats were nephrectomized and the extracellular volume was determined with 51Cr-labelled EDTA. Plasma volumes were measured with 125I-labelled human serum albumin or rat IgM in a separate series. Steady state concentrations of probes were determined in the interstitial fluid that was isolated by centrifugation from tumours or by post mortem wick implantation in the back skin. Calculations were made for interstitial fluid volume (Vi), along with the available (Va/Vi) and excluded (Ve/Vi) relative interstitial volume fractions. The Ve/Vi for the positively charged trastuzumab in tumours averaged 0.29 ± 0.03 (n = 16), a value which was significantly lower than the corresponding one for IgG of 0.36 ± 0.02 (n = 16). Native albumin was excluded from 38% of the tumour interstitial fluid, whereas cationization of albumin reduced the excluded volume by ∼50%. Our experiments suggest that the tumour interstitium acts as a negatively charged matrix and is an important factor in determining the macromolecular distribution volume. PMID:15994186

The interstitial distribution of macromolecules in rat tumours is influenced by the negatively charged matrix components.

PubMed

Wiig, Helge; Gyenge, Christina C; Tenstad, Olav

2005-09-01

Knowledge of macromolecular distribution volumes is essential in understanding fluid transport within normal and pathological tissues. In this study in vivo we determined the distribution volumes of several macromolecules, including one monoclonal antibody, in tumours and tested whether charges associated with the tumour extracellular matrix influence their available volumes. Steady state levels of the monoclonal antibody trastuzumab (Herceptin) (pI = 9.2), IgG (pI = 7.6) as well as native (pI = 5.0) and cationized albumin (pI = 7.6) were established in rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours by continuous infusion using osmotic minipumps. After a 5-7 day infusion period, the rats were nephrectomized and the extracellular volume was determined with 51Cr-labelled EDTA. Plasma volumes were measured with 125I-labelled human serum albumin or rat IgM in a separate series. Steady state concentrations of probes were determined in the interstitial fluid that was isolated by centrifugation from tumours or by post mortem wick implantation in the back skin. Calculations were made for interstitial fluid volume (Vi), along with the available (Va/Vi) and excluded (Ve/Vi) relative interstitial volume fractions. The Ve/Vi for the positively charged trastuzumab in tumours averaged 0.29 +/- 0.03 (n = 16), a value which was significantly lower than the corresponding one for IgG of 0.36 +/- 0.02 (n = 16). Native albumin was excluded from 38% of the tumour interstitial fluid, whereas cationization of albumin reduced the excluded volume by approximately 50%. Our experiments suggest that the tumour interstitium acts as a negatively charged matrix and is an important factor in determining the macromolecular distribution volume.

Perilymph composition in scala tympani of the cochlea: influence of cerebrospinal fluid.

PubMed

Hara, A; Salt, A N; Thalmann, R

1989-11-01

A commonly used technique to obtain cochlear perilymph for analysis has been the aspiration of samples through the round window membrane. The present study has investigated the influence of the volume withdrawn on sample composition in the guinea pig. Samples of less than 200 nl in volume taken through the round window showed relatively high glycine content, comparable to the level found in samples taken from scala vestibuli. If larger volumes are withdrawn, lower glycine levels are observed. This is consistent with cerebrospinal fluid (having a low glycine content) being drawn into scala tympani through the cochlear aqueduct and contaminating the sample. The existence of a concentration difference for glycine between scala tympani perilymph and cerebrospinal fluid suggests the physiologic communication across the cochlear aqueduct is relatively small in this species. The observation of considerable exchange between cerebrospinal fluid and perilymph, as reported in some studies, is more likely to be an artifact of the experimental procedures, rather than of physiologic significance. Alternative sampling procedures have been evaluated which allow larger volumes of uncontaminated scala tympani perilymph to be collected.

A diffusion tensor imaging tractography algorithm based on Navier-Stokes fluid mechanics.

PubMed

Hageman, Nathan S; Toga, Arthur W; Narr, Katherine L; Shattuck, David W

2009-03-01

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color images of the DTI dataset.

A Diffusion Tensor Imaging Tractography Algorithm Based on Navier-Stokes Fluid Mechanics

PubMed Central

Hageman, Nathan S.; Toga, Arthur W.; Narr, Katherine; Shattuck, David W.

2009-01-01

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color (DEC) images of the DTI dataset. PMID:19244007

Method and apparatus for probing relative volume fractions

DOEpatents

Jandrasits, Walter G.; Kikta, Thomas J.

1998-01-01

A relative volume fraction probe particularly for use in a multiphase fluid system includes two parallel conductive paths defining therebetween a sample zone within the system. A generating unit generates time varying electrical signals which are inserted into one of the two parallel conductive paths. A time domain reflectometer receives the time varying electrical signals returned by the second of the two parallel conductive paths and, responsive thereto, outputs a curve of impedance versus distance. An analysis unit then calculates the area under the curve, subtracts the calculated area from an area produced when the sample zone consists entirely of material of a first fluid phase, and divides this calculated difference by the difference between an area produced when the sample zone consists entirely of material of the first fluid phase and an area produced when the sample zone consists entirely of material of a second fluid phase. The result is the volume fraction.

CFD Analysis of nanofluid forced convection heat transport in laminar flow through a compact pipe

NASA Astrophysics Data System (ADS)

Yu, Kitae; Park, Cheol; Kim, Sedon; Song, Heegun; Jeong, Hyomin

2017-08-01

In the present paper, developing laminar forced convection flows were numerically investigated by using water-Al2O3 nano-fluid through a circular compact pipe which has 4.5mm diameter. Each model has a steady state and uniform heat flux (UHF) at the wall. The whole numerical experiments were processed under the Re = 1050 and the nano-fluid models were made by the Alumina volume fraction. A single-phase fluid models were defined through nano-fluid physical and thermal properties calculations, Two-phase model(mixture granular model) were processed in 100nm diameter. The results show that Nusselt number and heat transfer rate are improved as the Al2O3 volume fraction increased. All of the numerical flow simulations are processed by the FLUENT. The results show the increment of thermal transfer from the volume fraction concentration.

Method and apparatus for probing relative volume fractions

DOEpatents

Jandrasits, W.G.; Kikta, T.J.

1998-03-17

A relative volume fraction probe particularly for use in a multiphase fluid system includes two parallel conductive paths defining therebetween a sample zone within the system. A generating unit generates time varying electrical signals which are inserted into one of the two parallel conductive paths. A time domain reflectometer receives the time varying electrical signals returned by the second of the two parallel conductive paths and, responsive thereto, outputs a curve of impedance versus distance. An analysis unit then calculates the area under the curve, subtracts the calculated area from an area produced when the sample zone consists entirely of material of a first fluid phase, and divides this calculated difference by the difference between an area produced when the sample zone consists entirely of material of the first fluid phase and an area produced when the sample zone consists entirely of material of a second fluid phase. The result is the volume fraction. 9 figs.

Thermally developed peristaltic propulsion of magnetic solid particles in biorheological fluids

NASA Astrophysics Data System (ADS)

Bhatti, M. M.; Zeeshan, A.; Tripathi, D.; Ellahi, R.

2018-04-01

In this article, effects of heat and mass transfer on MHD peristaltic motion of solid particles in a dusty fluid are investigated. The effects of nonlinear thermal radiation and Hall current are also taken into account. The relevant flow analysis is modelled for fluid phase and dust phase in wave frame by means of Casson fluid model. Computation of solutions is presented for velocity profile, temperature profile and concentration profile. The effects of all the physical parameters such as particle volume fraction, Hartmann number, Hall Effect, Prandtl number, Eckert number, Schmidt number and Soret number are discussed mathematically and graphically. It is noted that the influence of magnetic field and particle volume fraction opposes the flow. Also, the impact of particle volume fraction is quite opposite on temperature and concentration profile. This model is applicable in smart drug delivery systems and bacteria movement in urine flow through the ureter.

Implementation of a Water Flow Control System into the ISS'S Planned Fluids & Combustion Facility

NASA Technical Reports Server (NTRS)

Edwards, Daryl A.

2003-01-01

The Fluids and Combustion Facility (FCF) will become an ISS facility capable of performing basic combustion and fluids research. The facility consists of two independent payload racks specifically configured to support multiple experiments over the life of the ISS. Both racks will depend upon the ISS's Moderate Temperature Loop (MTL) for removing waste heat generated by the avionics and experiments operating within the racks. By using the MTL, constraints are imposed by the ISS vehicle on how the coolant resource is used. On the other hand, the FCF depends upon effective thermal control for maximizing life of the hardware and for supplying proper boundary conditions for the experiments. In the implementation of a design solution, significant factors in the selection of the hardware included ability to measure and control relatively low flow rates, ability to throttle flow within the time constraints of the ISS MTL, conserve energy usage, observe low mass and small volume requirements. An additional factor in the final design solution selection was considering how the system would respond to a loss of power event. This paper describes the method selected to satisfy the FCF design requirements while maintaining the constraints applied by the ISS vehicle.

Fluid and electrolyte shifts in women during +Gz acceleration after 15 days' bed rest

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Stinnett, H. O.; Davis, G. L.; Kollias, J.; Bernauer, E. M.

1977-01-01

Experiments were conducted on twelve women aged 23-34 yr - a bed rest (BR) group of eight subjects and an ambulatory (AMB) group of four subjects - to determine the effect of bed rest on shifts in plasma volume, electrolytes, and erythrocyte volume during +Gz acceleration on a centrifuge. The BR group underwent the +Gz acceleration during a two-week ambulatory control period, after 15 days of a 17-day BR period, and on the third day of ambulatory recovery. The AMB group underwent the same experimental procedures, but continued their normal daily routine during the BR period without additional prescribed physical exercise. Major conclusions are that (1) the higher the mean control tolerance, the greater the tolerance decline after BR; (2) relative confinement and reduced activity contribute as much to reduction in tolerance as does the horizontal body position during BR; (3) BR deconditioning has no effect on the erythrocyte volume during +3.0 Gz; and (4) about one-half the loss in tolerance after BR can be attributed to plasma volume and electrolyte shifts.

The MR appearance of volume overload in the lower extremities

NASA Technical Reports Server (NTRS)

Meler, J. D.; Solomon, M. A.; Steele, J. R.; Yancy, C. W. Jr; Parkey, R. W.; Fleckenstein, J. L.; Blomqvist, C. G. (Principal Investigator)

1997-01-01

PURPOSE: Our goal was to describe the MR findings of volume overload (VO) in the lower extremities. METHOD: Fifteen individuals were studied, including eight healthy controls and seven patients with VO (four cardiac, three renal). MR evaluation included various SE techniques. Edema detection, localization, and symmetry were assessed subjectively. Relaxation time estimates were also made of the subcutaneous tissue, marrow, and three muscles. RESULTS: Subcutaneous tissue was markedly edematous in seven of seven patients and asymmetric in four of seven, whereas marrow was normal in all patients. Muscle edema was mild and asymmetric in six and two of seven patients, respectively. Perifascial fluid collections were identified in six of seven patients. CONCLUSION: Subcutaneous tissue edema is the dominant feature of VO in the lower extremities. Perifascial fluid is common but does not necessarily distribute symmetrically. Muscle edema is relatively mild. These findings should aid in identifying VO as the potential cause of swelling in patients with swollen legs.

Fluid-electrolyte shifts and thermoregulation - Rest and work in heat with head cooling

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Van Beaumont, W.; Brock, P. J.; Montgomery, L. D.; Morse, J. T.; Shvartz, E.; Kravik, S.

1980-01-01

The effects of head cooling on thermoregulation and associated plasma fluid and electrolyte shifts during rest and submaximal exercise in the heat are investigated. Thermoregulatory responses and plasma volume were measured in four male subjects fitted with liquid-cooled neoprene headgear during 60 min of rest, 60 min of ergometer exercise at 45% maximal oxygen uptake and 30 min of recovery in the supine position at 40.1 C and 40% relative humidity. It is found that, compared to control responses, head cooling decreased thigh sweating and increased mean skin temperature at rest and attenuated increases in thigh sweating, heart rate, rectal temperature and ventilation during exercise. During recovery, cooling is observed to facilitate decreases in sweat rate, heart rate, rectal temperature and forearm blood flow and enhance the increase in average temperature. Cooling had no effect on plasma protein, osmotic or electrolyte shifts, and decreased plasma volume losses. The findings indicate the effectiveness of moderate head cooling for the improvement of human performance during exercise in heat.

Modeling of Compressible Flow with Friction and Heat Transfer Using the Generalized Fluid System Simulation Program (GFSSP)

NASA Technical Reports Server (NTRS)

Bandyopadhyay, Alak; Majumdar, Alok

2007-01-01

The present paper describes the verification and validation of a quasi one-dimensional pressure based finite volume algorithm, implemented in Generalized Fluid System Simulation Program (GFSSP), for predicting compressible flow with friction, heat transfer and area change. The numerical predictions were compared with two classical solutions of compressible flow, i.e. Fanno and Rayleigh flow. Fanno flow provides an analytical solution of compressible flow in a long slender pipe where incoming subsonic flow can be choked due to friction. On the other hand, Raleigh flow provides analytical solution of frictionless compressible flow with heat transfer where incoming subsonic flow can be choked at the outlet boundary with heat addition to the control volume. Nonuniform grid distribution improves the accuracy of numerical prediction. A benchmark numerical solution of compressible flow in a converging-diverging nozzle with friction and heat transfer has been developed to verify GFSSP's numerical predictions. The numerical predictions compare favorably in all cases.