scholarly journals The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study.

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1997 ◽  
Author(s):  
Fredrik Leijonhufvud ◽  
Fredrik Jöneby ◽  
Jan G. Jakobsson
Keyword(s):  
Gas Flow ◽  
Anaesthetic Agent ◽  
Point Of View ◽  
Low Flow ◽  
Test Lung ◽  
Minimal Alveolar Concentration ◽  
Flow Rates ◽  
Optimal Flow ◽  
Gas Consumption ◽  
The Impact

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system ( wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p<0.05) at higher flow rates (1 – 2 – 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates < 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The “optimal FGF” for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems “optimal” taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out.

scholarly journals The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study.

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1997 ◽  
Author(s):  
Fredrik Leijonhufvud ◽  
Fredrik Jöneby ◽  
Jan G. Jakobsson
Keyword(s):  
Gas Flow ◽  
Anaesthetic Agent ◽  
Point Of View ◽  
Low Flow ◽  
Test Lung ◽  
Minimal Alveolar Concentration ◽  
Flow Rates ◽  
Optimal Flow ◽  
Gas Consumption ◽  
The Impact

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system (wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p<0.05) at higher flow rates (1 – 2 – 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates < 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The “optimal FGF” for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems “optimal” taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out

scholarly journals Influence of mass transfer on bubble plume hydrodynamics

2016 ◽  
Vol 88 (1) ◽  
pp. 411-422 ◽  
Author(s):  
IRAN E. LIMA NETO ◽  
PRISCILA A.B. PARENTE
Keyword(s):  
Mass Transfer ◽  
Gas Flow ◽  
Low Flow ◽  
Integral Model ◽  
Bubble Plume ◽  
Flow Rates ◽  
Functional Relationships ◽  
Bubble Plumes ◽  
The Impact ◽  
Water Depths

ABSTRACT This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coefficient and factor of momentum amplification due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas flow rates and water depths. The results revealed a relevant impact when fine bubbles are considered, even for moderate water depths. Additionally, model simulations indicate that for weak bubble plumes (i.e., with relatively low flow rates and large depths and slip velocities), both dissolution and turbulence can affect plume hydrodynamics, which demonstrates the importance of taking the momentum amplification factor relationship into account. For deeper water conditions, simulations of bubble dissolution/decompression using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Sensitivity analysis showed that the water depth, followed by the bubble size and the flow rate are the most important parameters that affect plume hydrodynamics. Lastly, dimensionless correlations are proposed to assess the impact of mass transfer on plume hydrodynamics, including both the aeration and oxygenation modes.

Experimental Analysis of Different Coolants Used in Plasma Cutting Operation for the Improved Electrode Life

2015 ◽  
Vol 719-720 ◽  
pp. 46-49 ◽  
Author(s):  
Ginka Ranga Janardhana ◽  
Mani Senthil Kumar ◽  
B. Dhanasekar
Keyword(s):  
Temperature Rise ◽  
Metal Cutting ◽  
Cooling System ◽  
Heat Removal ◽  
Plasma Cutting ◽  
Life Test ◽  
Flow Rates ◽  
Optimal Flow ◽  
Cutting Operation ◽  
The Impact

The plasma cutting technology has been emerged as a developing technology which finds tremendous potential in fabrication and metal cutting industries. Thus for the cutting operation, the electrode inside the plasma torch plays a vital role for the plasma arc generation. The temperature of the arc is very high and at the electrode is around 3500°C. The cutting torch requires proper cooling system in order to prevent the electrode from quick wear due to the existence of high thermal gradient. The presented work aimed to study the impact of three coolants propylene glycol, ethylene glycol and de-ionized water flow over the electrode life. The experimental setups were arranged to study the heat transfer capabilities of the three coolants for different flow values and aimed to achieve the optimal flow rates for the efficient heat removal. The electrode life test trials were conducted to measure the electrode life for the flow values of three coolants in the temperature rise test. The optimal flow rates arrived from temperature rise test and the electrode life measured from life test are compared for the three coolant cases considered.

scholarly journals Promoting low-flow anaesthesia and volatile anaesthetic agent choice

2019 ◽  
Vol 8 (3) ◽  
pp. e000479 ◽  
Author(s):  
Louise A Carter ◽  
Molola Oyewole ◽  
Eleanor Bates ◽  
Kate Sherratt
Keyword(s):  
Gas Flow ◽  
Anaesthetic Agent ◽  
Cost Effective ◽  
Low Flow ◽  
Volatile Agent ◽  
Monthly Basis ◽  
Improvement Project ◽  
Effective Manner ◽  
Low Flow Anaesthesia ◽  
Volatile Agents

BackgroundAs doctors, we are increasingly aware of the financial implications of our practice. The need to work in a more conscientious, efficacious and cost-effective manner is greater than ever before. Environmental and financial benefits can be seen through employing the use of low-flow anaesthesia.AimsThis quality improvement project aimed to make anaesthetic practice more environmentally friendly and to reduce departmental spending. This could be achieved by promoting the use of low-flow anaesthesia and by encouraging isoflurane use where appropriate.MethodsAll anaesthetic consultants and trainees were invited to fill out an initial questionnaire relating to their personal preferences and practices when conducting anaesthesia. There were specific questions relating to low-flow anaesthesia and isoflurane use. Our main measure of improvement was any decrease in the number of bottles of volatile agent ordered by the department from pharmacy. Monthly spot audits were conducted to assess gas flow rates and volatile agent use in theatre. Departmental spending figures relating to the purchase of volatile agent bottles were obtained from pharmacy. Information was then disseminated to anaesthetists on a monthly basis via a ‘low-flow board’, which showed pictorial and graphical representations of differing gas flows and volatile agent usage in relation to cost.ResultsOur project showed a trend for the increased use of low-flow anaesthesia within the department. We also showed a decrease in the number of bottles of volatile agent ordered: 18% fewer bottles ordered compared with the same period the previous year. This represented a 25% decrease in total departmental expenditure on volatile agents despite an increase in theatre activity.ConclusionIncreasing awareness regarding anaesthetic choices and promoting low-flow anaesthesia and isoflurane use, translated into an overall decreased departmental spend on volatile agents without affecting patient care.

scholarly journals Treatment of oil and heavy metal contaminated water

2019 ◽  
pp. 83-88
Author(s):  
Bengt Sahlin ◽  
Sune Berg ◽  
K. Hakan Anderberg ◽  
Fredrik Tengstrom
Keyword(s):  
Environmental Management System ◽  
Spare Parts ◽  
Point Of View ◽  
Process Water ◽  
Low Flow ◽  
Modular System ◽  
Contaminated Water ◽  
Flow Rates ◽  
Wide Range ◽  
Voluntary Certification

The presence of oil contaminated water in many industrial processes causes a need for the development of techniques to purify waste process water. Purified process water can be reused, which is an advantage from an ecological as well as a financial point of view. Reuse of process water enables a reduction in water consumption, reduces the use of chemicals and results in less water that has to be disposed of. These factors will motivate companies to invest in equipment for purification of waste process water even if the flow rates are low. TTM-produkter is a Swedish company based in Kalmar aiming at developing know-how and equipment for water treatment. The company is together with the University of Kalmar developing a modular system for purification of process- and wastewater. The system will be on a low investment level, easy to operate and therefore well suited for small and mediumsized companies. The system will be tailored for a number of defined applications, easy to install and require almost no construction work on the building. A standard installation consists of a sludge and oil separator in polyethene placed on the floor, a hydrocyclone to remove particles and two filter cartridges filled with smart/selective adsorbents. Until now about 30 installations of the system have been made in Sweden and Poland. The installations cover a wide range of different industries such as car and bus washes, car demolishing plants, laundry services and ceramic, metal and graphic workshops. The best results from an ecological as well as a financial point of view has been achieved in mediumsized operations with a low flow rate of waste process water, for example a plant where 1-5 buses are washed each day or a machine for washing spare parts at a car demolishing plant. New environmental legislation and voluntary certification in accordance with ISO 1 4001 Environmental Management System not only forces but also motivates companies to invest in systems for treatment of waste process water even if the flow rates are low.

scholarly journals Investigations of wall effect on permeability through porous media at low flow rates

2017 ◽  
Vol 18 (1) ◽  
pp. 233-239 ◽  
Author(s):  
Rajat Kango ◽  
M. A. Alam ◽  
Vijay Shankar
Keyword(s):  
Point Of View ◽  
Wall Effect ◽  
Low Flow ◽  
Pressure Measurements ◽  
Relative Resistance ◽  
Seepage Velocity ◽  
Flow Rates ◽  
Bed Materials ◽  
Constant Head ◽  
Fluid Characteristics

Abstract The study of percolation of fluids through permeable subsoil strata has always been a subject of great significance from engineering point of view. The permeability depends upon both material properties and fluid characteristics. Previous studies are concentrated on the influence of regularly shaped particles on permeability, whereas the present study aims to analyse its variation due to natural randomly shaped particles. Seepage velocity of the fluid and hydraulic gradient of the soil bed materials are evaluated with the help of discharge and pressure measurements in a constant head permeameter. Specific gravity tests are conducted on different materials in order to calculate their porosities. The dependence of permeability on Dp/dg (i.e. ratio of permeameter size (Dp) to particle size (dg)) for various wall effect conditions is analysed through standard experimental procedures. The present study examines the effect of relative resistance of permeameter wall (i.e. the ratio of permeability of confined to unconfined bed) on Dp/dg. The results reveal that the aquifer confinement i.e. the distance up to which the region of randomly packing occurs directly influences the measure of permeability at lower values of Dp/dg. This effect decreases with increasing values of Dp/dg and becomes negligible at values 120 and above.

Effect of Flow Rates on Operation of a Solar Thermochemical Reactor for Splitting CO2 Via the Isothermal Ceria Redox Cycle

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Brandon J. Hathaway ◽  
Rohini Bala Chandran ◽  
Stephen Sedler ◽  
Daniel Thomas ◽  
Adam Gladen ◽  
...  
Keyword(s):  
Heat Recovery ◽  
Gas Flow ◽  
Gas Flows ◽  
Energy Costs ◽  
Redox Cycle ◽  
External Energy ◽  
Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Solar Thermochemical ◽  
The Impact

A prototype 4 kW solar thermochemical reactor for the continuous splitting of carbon dioxide via the isothermal ceria redox cycle is demonstrated. These first tests of the new reactor showcase both the innovation of continuous on-sun fuel production in a single reactor and remarkably effective heat recovery of the sensible heat of the reactant and product gases. The impact of selection of gas flow rates is explored with respect to reactor fuel productivity and external energy costs of gas separation and pumping. Thermal impacts of gas flow selection are explored by coupling measured temperatures with a computational fluid dynamics (CFD) model to calculate internal temperature distributions and estimate heat recovery. Optimized gas flows selected for operation provide a 75% increase in fuel productivity and reduction in parasitic energy costs by 10% with respect to the design case.

scholarly journals Regulation of glomerulotubular balance. I. Impact of dopamine on flow-dependent transport

2012 ◽  
Vol 303 (3) ◽  
pp. F386-F395 ◽  
Author(s):  
Zhaopeng Du ◽  
Qingshang Yan ◽  
Laxiang Wan ◽  
Sheldon Weinbaum ◽  
Alan M. Weinstein ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Proximal Tubules ◽  
Low Flow ◽  
Flow Rates ◽  
Luminal Flow ◽  
Flow Stimulation ◽  
Dependent Transport ◽  
The Impact ◽  
Glomerulotubular Balance

In response to volume expansion, locally generated dopamine decreases proximal tubule reabsorption by reducing both Na/H-exchanger 3 (NHE3) and Na-K-ATPase activity. We have previously demonstrated that mouse proximal tubules in vitro respond to changes in luminal flow with proportional changes in Na+ and HCO3− reabsorption and have suggested that this observation underlies glomerulotubular balance. In the present work, we investigate the impact of dopamine on the sensitivity of reabsorptive fluxes to changes in luminal flow. Mouse proximal tubules were microperfused in vitro at low and high flow rates, and volume and HCO3− reabsorption (Jv and JHCO3) were measured, while Na+ and Cl− reabsorption (JNa and JCl) were estimated. Raising luminal flow increased Jv, JNa, and JHCO3 but did not change JCl. Luminal dopamine did not change Jv, JNa, and JHCO3 at low flow rates but completely abolished the increments of Na+ absorption by flow and partially inhibited the flow-stimulated HCO3− absorption. The remaining flow-stimulated HCO3− absorption was completely abolished by bafilomycin. The DA1 receptor blocker SCH23390 and the PKA inhibitor H89 blocked the effect of exogenous dopamine and produced a two to threefold increase in the sensitivity of proximal Na+ reabsorption to luminal flow rate. Under the variety of perfusion conditions, changes in cell volume were small and did not always parallel changes in Na+ transport. We conclude that 1) dopamine inhibits flow-stimulated NHE3 activity by activation of the DA1 receptor via a PKA-mediated mechanism; 2) dopamine has no effect on flow-stimulated H-ATPase activity; 3) there is no evidence of flow stimulation of Cl− reabsorption; and 4) the impact of dopamine is a coordinated modulation of both luminal and peritubular Na+ transporters.

scholarly journals Comparison of Circular and Parallel-Plated Membrane Lungs for Extracorporeal Carbon Dioxide Elimination

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 398
Author(s):  
Leonie S. Schwärzel ◽  
Anna M. Jungmann ◽  
Nicole Schmoll ◽  
Stefan Caspari ◽  
Frederik Seiler ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Flow ◽  
Removal Rate ◽  
Low Flow ◽  
Chronic Obstructive ◽  
Co2 Removal ◽  
Circular Membrane ◽  
Flow Rates ◽  
Polypropylene Membrane ◽  
Removal Capacity

Extracorporeal carbon dioxide removal (ECCO2R) is an important technique to treat critical lung diseases such as exacerbated chronic obstructive pulmonary disease (COPD) and mild or moderate acute respiratory distress syndrome (ARDS). This study applies our previously presented ECCO2R mock circuit to compare the CO2 removal capacity of circular versus parallel-plated membrane lungs at different sweep gas flow rates (0.5, 2, 4, 6 L/min) and blood flow rates (0.3 L/min, 0.9 L/min). For both designs, two low-flow polypropylene membrane lungs (Medos Hilte 1000, Quadrox-i Neonatal) and two mid-flow polymethylpentene membrane lungs (Novalung Minilung, Quadrox-iD Pediatric) were compared. While the parallel-plated Quadrox-iD Pediatric achieved the overall highest CO2 removal rates under medium and high sweep gas flow rates, the two circular membrane lungs performed relatively better at the lowest gas flow rate of 0.5 L/min. The low-flow Hilite 1000, although overall better than the Quadrox i-Neonatal, had the most significant advantage at a gas flow of 0.5 L/min. Moreover, the circular Minilung, despite being significantly less efficient than the Quadrox-iD Pediatric at medium and high sweep gas flow rates, did not show a significantly worse CO2 removal rate at a gas flow of 0.5 L/min but rather a slight advantage. We suggest that circular membrane lungs have an advantage at low sweep gas flow rates due to reduced shunting as a result of their fiber orientation. Efficiency for such low gas flow scenarios might be relevant for possible future portable ECCO2R devices.

scholarly journals Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 389 ◽  
Author(s):  
Petter Jakobsson ◽  
Madleine Lindgren ◽  
Jan G. Jakobsson
Keyword(s):  
Gas Flow ◽  
Anaesthetic Machine ◽  
Flow Time ◽  
Lung Model ◽  
Low Flow ◽  
Major Influence ◽  
Test Lung ◽  
Depth Of Anaesthesia ◽  
Low Flow Anaesthesia ◽  
End Tidal

Background:Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods:We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

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