In Vitro Perfusion of Hybrid Artificial Pancreas Devices at Low Flow Rates

ASAIO Journal ◽  
1992 ◽  
Vol 38 (3) ◽  
pp. M443-M449 ◽  
Author(s):  
CARLOS A. RAMÍREZ ◽  
MILDRED LÓPEZ ◽  
CONNIE L. STEPHENS
Keyword(s):  
Artificial Pancreas ◽  
Low Flow ◽  
In Vitro Perfusion ◽  
Flow Rates

scholarly journals In vitro estimation of the energy loss through turbulence in a porcine aortic valve stenosis model and silicone ascending aorta phantom using backlight particle tracking velocimetry

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
M Chiarelli ◽  
S F De Marchi ◽  
D Obrist ◽  
E Buffle
Keyword(s):  
Left Ventricle ◽  
Aortic Stenosis ◽  
Energy Loss ◽  
Particle Tracking Velocimetry ◽  
Ascending Aorta ◽  
Low Flow ◽  
Mean Flow ◽  
Flow Rates ◽  
Stenosis Severity

Abstract Introduction Patients suffering from low-flow, low-gradient aortic stenosis present a decreased stroke volume due to decreased contraction or relaxation function of the left ventricle. As a low stroke volume tends to cause a low transvalvular flow, transvalvular pressure gradient (TVPG) and effective orifice area, the clinician cannot rely on those parameters with confidence for the evaluation of aortic stenosis severity. Hence new diagnostic parameters have to be developed. Energy loss through turbulence associated with aortic stenosis represented the wasted left ventricle work. Currently, echocardiographic measurement of the turbulence intensity is not validated for clinical evaluations of aortic stenosis. Methods Two porcine aortic valves were harvested and inserted in a flow loop that replicates the pulsatile flow of the heart. A stiffening of the valves was achieved by treating them with formaldehyde. The stiffening was externally confirmed by a custom-made force-displacement device quantifying the rigidity of the leaflet yielding two stiffness grades per valve. Each valve was tested under three different mean flow rates (1, 2.5, and 4 l/min) at each of the two stiffness grades. Moreover the pressure in the left ventricle chamber and in the aortic chamber was recorded to calculate the TVPG. Particle tracking velocimetry measurements into the transparent silicone ascending aorta phantom allowed the computation of the turbulent kinetic energy (TKE), to evaluate the energy loss due to turbulence. Results We could confirm the enhanced rigidity of the valve leaflets with our custom device (data not shown) and measure a consistent increase in TVPG across all mean flow rates between the two stiffness grades. Moreover, an explicit increase of the TKE in the aortic phantom could be measured after the stiffening process (73.1% under 1 l/min, and 43% under both 2.5 and 4 l/min). In addition, a good correlation (R = 0.86) between the mean TVPG and the TKE was found. Conclusions This project demonstrated the possibility of quantifying the energy loss attributed to turbulence for porcine valves in vitro for native and added stiffness grade. This project lays the foundation for the development of a new diagnostic tool for the assessment of stenosis severity in patients with low-flow, low-gradient aortic stenosis in cardiac imaging tool such as echocardiography. FUNDunding Acknowledgement Type of funding sources: None. TVPG and its correlation with TKE Intensity graphs of the TKE

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 Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

A comparison of two non-radioactive digesta marker systems for the measurement of nutrient flow at the proximal duodenum of calves

1978 ◽  
Vol 90 (1) ◽  
pp. 157-163 ◽  
Author(s):  
D. E. Beever ◽  
R. C. Kellaway ◽  
D. J. Thomson ◽  
J. C. MacRae ◽  
C. C. Evans ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Low Flow ◽  
Dual Phase ◽  
Regression Equations ◽  
Flow Rates ◽  
Proximal Duodenum ◽  
Dietary Component ◽  
Sodium And Potassium

SUMMARYThe use of non-radioactive ruthenium phenanthroline (Ru-P) and chromium EDTA (Cr-EDTA) as dual phase markers of digesta flow was examined and compared with chromium sesquioxide (Cr2O3) in conjunction with spot samples of digesta collected from T-shaped cannulae situated in the proximal duodenum of weaned calves.In vitro estimates of organic matter digestibility indicated that on a cubed barley diet, Ru-P exhibited toxic effects at concentrations on 2·2 × 10–5 M and above. No such effects were noted with Cr-EDTA. Subsequently satisfactory infusion rates of 12 mg Ru and 280 mg Cr/kg dry-matter intake were established.Daily flows of organic matter, starch, nitrogen, fibre, sodium and potassium at the proximal duodenum were calculated by the dual phase marker system and by Cr2O3, and regression equations relating these two for each dietary component were calculated. Examination of the intercepts revealed that they all differed significantly from zero (P < 0·05) whilst all the regression coefficients were significantly different from unity (P < 0·05), thus indicating that Cr2O3 underestimated nutrient flows at low flow rates and overestimated them at high flow rates relative to the corresponding estimates based on Ru-P plus Cr-EDTA.

scholarly journals Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2020 ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

scholarly journals Influence of flow rate, fluid temperature, and extension line on Hotline and S-line heating capability: an in vitro study

2020 ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using room-temperature or cold fluid. Administering of the warm fluid at the same flow rate significantly increased the TProx and TDistal values in S-line more than the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. Administering warm fluid in S-line prevented a decrease in the fluid temperature at a high flow rate. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

Flow-dependent potassium secretion by rabbit cortical collecting tubule in vitro

1987 ◽  
Vol 253 (5) ◽  
pp. F896-F903 ◽  
Author(s):  
B. G. Engbretson ◽  
L. C. Stoner
Keyword(s):  
Flow Rate ◽  
Axial Flow ◽  
Low Flow ◽  
Sodium Reabsorption ◽  
Flow Rates ◽  
Chemical Gradients ◽  
Special Diet ◽  
Potassium Secretion ◽  
Collecting Tubules

Cortical collecting tubules (CCT) dissected from rabbits fed a diet designed to stimulate potassium transport secreted potassium in direct proportion to the flow rate in the range of 0.4-3 nl/min (r = 0.79). This relationship was also evident in tubules from rabbits maintained on standard laboratory chow (r = 0.80). The slope of the line relating the two parameters was almost six times greater in tubules from animals fed the special diet. When the range of flow rates was expanded, potassium secretion in nine CCTs appeared to peak at 5-6 nl/min and then failed to increase despite further elevation of flow to nearly 15 nl/min. We investigated the effects of the electrical and chemical gradients on flow-dependent potassium secretion. Because transepithelial voltage was unaffected by changes in axial flow, we conclude that the flow-dependent fraction of potassium secretion is not explained by the electrical gradient. To evaluate the role of luminal potassium concentration on flow-dependent potassium secretion, 11 CCTs were perfused with both 5 and 50 mM potassium solutions at two flow rates (approximately 1.5 and 4.0 nl/min). Increases in both potassium secretion (15.6 +/- 3.9 peq.mm-1.min-1) and sodium reabsorption (11.9 +/- 5.2 peq.mm-1.min-1) were evident in the tubules perfused with 5 mM potassium. Potassium secretion was not reduced by 50 mM luminal potassium at the low flow rate when the largest chemical gradients opposing net secretion were generated. When 50 mM potassium was present in the lumen, increasing flow did not stimulate potassium secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Influence of Flow Rate, Fluid Temperature, and Extension Line on Hotline and S-Line Heating Capability: an in Vitro Study

2020 ◽  
Author(s):  
Hosu Kim ◽  
Tae Kyong Kim ◽  
Sukha Yoo ◽  
Jin-Tae Kim
Keyword(s):  
Flow Rate ◽  
Room Temperature ◽  
In Vitro Study ◽  
High Flow ◽  
High Flow Rate ◽  
Low Flow ◽  
Fluid Temperature ◽  
Flow Rates ◽  
Fluid Warmer

Abstract Background A fluid warmer can prevent hypothermia during the perioperative period. This study evaluated the heating capabilities of Hotline and Barkey S-line under different flow rates and initial fluid temperatures, as well as after the extension line installation. Methods We measured the temperature of a 0.9% sodium chloride solution at the fluid warmer outlet (TProx) and the extension line end (TDistal) with three different initial fluid temperatures (room, warm, and cold) and two flow rates (250 ml/hr and 100 mL/hr). Results At a 250 ml/hr flow rate, the TProx and TDistal values were observed to be higher in Hotline than in S-line when using a room-temperature fluid; similar results were observed for the cold fluid. Administration of the warm fluid was observed to significantly increase the TProx and TDistal values in S-line at rates of 250 ml/hr more than the administration of the cold and room-temperature fluids. At flow rates of 100 ml/hr, TDistal values were significantly lower than TProx values in both devices regardless of the initial fluid temperature. Conclusions Hotline outperformed S-line for warming fluids at a high flow rate with cold or room-temperature fluids. The administration of the initially warm fluid prevented a decrease in the fluid temperature at a high flow rate in S-line. However, at a low flow rate, the fluid temperature significantly decreased in both devices after passing through an extension line.

The Effect of Heparin vs. Citrate on the Interaction of Platelets with Vascular Graft Materials

1985 ◽  
Vol 54 (04) ◽  
pp. 842-848 ◽  
Author(s):  
Kandice Kottke-Marchant ◽  
James M Anderson ◽  
Albert Rabinovitch ◽  
Richard A Huskey ◽  
Roger Herzig
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Vascular Graft ◽  
Time Course ◽  
Platelet Reactivity ◽  
Polymer Surfaces ◽  
In Vitro Perfusion ◽  
Citrate Anticoagulation ◽  
Platelet Release

SummaryHeparin is known to affect platelet function in vitro, but little is known about the effect of heparin on the interaction of platelets with polymer surfaces in general, and vascular graft materials in particular. For this reason, the effect of heparin vs. citrate anticoagulation on the interaction of platelets with the vascular graft materials expanded polytetrafluoroethylene (ePTFE), Dacron Bionit (DB) and preclotted Dacron Bionit (DB/PC) was studied in a recirculating, in vitro perfusion system. Platelet activation, as shown by a decrease in platelet count, an increase in platelet release and a decrease in platelet aggregation, was observed for all vascular graft materials tested using heparin and was greater for Dacron and preclotted Dacron than for ePTFE. Significant differences between heparin and citrate anticoagulation were seen for platelet release, platelet aggregation and the relative ranking of material platelet-reactivity. However, the trends and time course of platelet activation were similar with both heparin and citrate for the materials tested.

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