scholarly journals Toward Development of a Higher Flow Rate Hemocompatible Biomimetic Microfluidic Blood Oxygenator

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 888
Author(s):  
Jose Santos ◽  
Else M. Vedula ◽  
Weixuan Lai ◽  
Brett C. Isenberg ◽  
Diana J. Lewis ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Single Layer ◽  
Blood Oxygenation ◽  
Gas Transfer ◽  
Large Area ◽  
Current Standard ◽  
Blood Distribution ◽  
Extracorporeal Lung Support ◽  
Recent Emergence

The recent emergence of microfluidic extracorporeal lung support technologies presents an opportunity to achieve high gas transfer efficiency and improved hemocompatibility relative to the current standard of care in extracorporeal membrane oxygenation (ECMO). However, a critical challenge in the field is the ability to scale these devices to clinically relevant blood flow rates, in part because the typically very low blood flow in a single layer of a microfluidic oxygenator device requires stacking of a logistically challenging number of layers. We have developed biomimetic microfluidic oxygenators for the past decade and report here on the development of a high-flow (30 mL/min) single-layer prototype, scalable to larger structures via stacking and assembly with blood distribution manifolds. Microfluidic oxygenators were designed with biomimetic in-layer blood distribution manifolds and arrays of parallel transfer channels, and were fabricated using high precision machined durable metal master molds and microreplication with silicone films, resulting in large area gas transfer devices. Oxygen transfer was evaluated by flowing 100% O2 at 100 mL/min and blood at 0–30 mL/min while monitoring increases in O2 partial pressures in the blood. This design resulted in an oxygen saturation increase from 65% to 95% at 20 mL/min and operation up to 30 mL/min in multiple devices, the highest value yet recorded in a single layer microfluidic device. In addition to evaluation of the device for blood oxygenation, a 6-h in vitro hemocompatibility test was conducted on devices (n = 5) at a 25 mL/min blood flow rate with heparinized swine donor blood against control circuits (n = 3). Initial hemocompatibility results indicate that this technology has the potential to benefit future applications in extracorporeal lung support technologies for acute lung injury.

Development of a self-pumping extracorporeal blood oxygenation device characterized by a rotating shaft with embedded fiber packages

2019 ◽  
Vol 43 (6) ◽  
pp. 393-400
Author(s):  
Antonino Rinaudo ◽  
Salvatore Pasta
Keyword(s):  
Blood Flow ◽  
Rotation Axis ◽  
Blood Oxygenation ◽  
Operating Conditions ◽  
Respiratory Support ◽  
Gas Transfer ◽  
Animal Testing ◽  
Rotating Shaft ◽  
Hollow Shaft

Introduction: To offer respiratory support for patients with lung disease, a novel technological solution for blood pumping and oxygenation is being developed. The pump–lung system was designed to integrate fiber membranes into six packages radially embedded in a rotating hollow shaft placed along the longitudinal axis of the device. Fiber packages are inclined with respect to the rotation axis so that the rotational motion of the rotating shaft allows a self-pumping system to be obtained. Method: Both hemodynamic and gas transfer performances were investigated using both in vitro experiments and in silico flow analyses. Results: The predicted flow velocity in the pump chamber was smooth and characterized by high peripheral velocities near the housing wall. As the blood flow enters the inlet, the static pressure increased with the angular momentum imparted to the fiber packages. Experiments confirmed that the proposed pump–lung system can provide adequate blood flow and oxygen transfer over the range of intended operating conditions (0.5–5 L/min and 500–1500 r/min). Conclusion: Although the study did not include animal testing, the novel pump-oxygenator solution is feasible for respiratory support in patients with lung diseases.

scholarly journals The Effect of Continuous Renal Replacement Therapy with the AN69ST Membrane on Inflammatory Markers and the Level of Consciousness of Hemodialysis Patients with Stroke: Comparison with Hemodialysis with Low Blood Flow Rate

PRILOZI ◽  
2018 ◽  
Vol 39 (2-3) ◽  
pp. 29-35
Author(s):  
Tomohiro Matsui ◽  
Takafumi Nakagawa ◽  
Hitomi Kikuchi ◽  
Hiroyuki Horio ◽  
Kazuhiko Hashimura
Keyword(s):  
Blood Flow ◽  
Renal Replacement Therapy ◽  
Continuous Renal Replacement Therapy ◽  
Replacement Therapy ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Current Standard ◽  
Reactive Protein ◽  
Inflammatory Parameters ◽  
Gcs Score

Abstract Introduction: Hemodialysis (HD) with low blood flow rate, continuous renal replacement therapy (CRRT), and peritoneal dialysis are recommended for patients with stroke complications to prevent intracranial hypertension because of the low diffusion capacity of the brain barrier. However, detailed guidelines are not currently available; thus, there is an urgent need to establish such guidelines. Material and Methods: We developed a novel protocol for performing CRRT with the AN69ST membrane, which has excellent adsorption capacity for various cytokines. The objective of this study was to compare the effect of the novel protocol with that of the current standard protocol, i.e. hemodialysis with low blood flow rate. To compare the effect of hemodialysis with low blood flow (HD group, n=27) and CRRT with AN69ST membrane (CRRT group, n=8), we measured the following consciousness and blood inflammatory parameters in patients with stroke complications at baseline and after 1 week of treatment: Glasgow Coma Scale (GCS) score, C-reactive protein (CRP) levels, and white blood cell (WBC) and platelet count. Results: After 1 week, the total GCS score did not improve in the HD group, but improved significantly in the CRRT group (HD group: 13.1±3.0 to 13.3±3.1, p=0.5508, CRRT group: 8.9±3.9 to 11.5±3.9, p=0.0313). Improvement in the CRRT group was significantly higher than in the HD group (p=0.0039). CRP levels did not change significantly in either the HD (3.8±5.5 to 5.3±4.3 n.s.) or CRRT groups (7.7±10.0 to 3.7±3.2 n.s.); however, they tended to increase in the HD group and decrease in the CRRT group. No significant changes were observed in WBC and platelet counts after 1 week of treatment in either group. Conclusion: CRRT with the AN69ST membrane might have a beneficial effect on the consciousness level and inflammation of patients with stroke.

Cost Optimization of a Multilayer Microchannel Dialyzer

2013 ◽  
Author(s):  
Mahshid Mohammadi ◽  
Kendra V. Sharp
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Cost Optimization ◽  
Life Quality ◽  
Single Layer ◽  
Blood Flow Rate ◽  
Porous Membrane ◽  
Dialysate Flow ◽  
Novel Approach ◽  
Dialysate Flow Rate

A microchannel-based hemodialyzer offers a novel approach to hemodialysis practice and holds many promises to improve kidney patients’ life quality and dialysis treatment efficiency. The hallow fiber hemodialyzer, a conventional dialysis device, has certain limitations including non-uniformity of the dialysate flow path which necessitates the use of a high dialysate flow rate. The microchannel-based hemodialyzer with flat membranes remarkably improves the mass transfer characteristics and enables the design of a smaller and less expensive unit with lower dialysate-to-blood flow rate ratios [1, 2]. In the microchannel-based design, successive stacked layers alternate between blood flow and dialysate flow. A porous membrane between these layers allows for the transport of toxins from blood side to dialysis fluid side. A schematic view of a single layer is shown in Fig. 1.

scholarly journals Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 956
Author(s):  
Philipp Taus ◽  
Adrian Prinz ◽  
Heinz D. Wanzenboeck ◽  
Patrick Schuller ◽  
Anton Tsenov ◽  
...  
Keyword(s):  
Electron Beam Lithography ◽  
Nanoimprint Lithography ◽  
Silicon Oxide ◽  
Three Dimensional ◽  
Single Layer ◽  
Fabrication Technology ◽  
Large Area ◽  
Structural Colors ◽  
Biomimetic Structures ◽  
Morpho Butterfly

Biomimetic structures such as structural colors demand a fabrication technology of complex three-dimensional nanostructures on large areas. Nanoimprint lithography (NIL) is capable of large area replication of three-dimensional structures, but the master stamp fabrication is often a bottleneck. We have demonstrated different approaches allowing for the generation of sophisticated undercut T-shaped masters for NIL replication. With a layer-stack of phase transition material (PTM) on poly-Si, we have demonstrated the successful fabrication of a single layer undercut T-shaped structure. With a multilayer-stack of silicon oxide on silicon, we have shown the successful fabrication of a multilayer undercut T-shaped structures. For patterning optical lithography, electron beam lithography and nanoimprint lithography have been compared and have yielded structures from 10 µm down to 300 nm. The multilayer undercut T-shaped structures closely resemble the geometry of the surface of a Morpho butterfly, and may be used in future to replicate structural colors on artificial surfaces.

scholarly journals Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7260
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Measurement Errors ◽  
Present Method ◽  
Test Fluid ◽  
Constant Flow Rate ◽  
Rbc Aggregation ◽  
Sinusoidal Flow ◽  
Analytical Expressions

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

EXTRACTION OF MINUTE GAS BUBBLES FROM LIQUIDS FLOWING IN A SIMULATED CARDIOPULMONARY BYPASS SYSTEM BY A VENTURI-ASPIRATOR UNIT

2002 ◽  
Vol 02 (03n04) ◽  
pp. 297-312
Author(s):  
WEN-JEI YANG ◽  
AMR EID ◽  
R. ECHIGO
Keyword(s):  
Cardiopulmonary Bypass ◽  
Flow Rate ◽  
Whole Blood ◽  
Pressure Difference ◽  
Gas Bubbles ◽  
Blood Oxygenation ◽  
Straight Tube ◽  
Suction Pressure ◽  
Total Flow ◽  
Total Flow Rate

An experimental study is performed to extract minute gas bubbles from liquids flowing in a simulated cardiopulmonary bypass system using a Venturi-aspirator unit. In other words, oxygen bubbles in oxygenated blood are simulated by air bubbles in water with AP30 (about same viscosity as whole blood). This study is intended to determine the feasibility of using a Venturi aspirator unit to extract minute gas bubbles from a simulated cardiopulmonary bypass system. Testing of the Venturi-type bubble extraction is carried out using three different test sections. Two Venturis are used, and a straight tube configuration is used as a control. The two Venturis are similar, with the exception that one has a longer inlet cone which causes the entering liquid to accelerate at a slower rate. Results are obtained for effectiveness of the aspirator unit as functions of total flow rate, extraction suction, suction pressure difference, and hydraulic head. It is concluded from the study that:(i) The effectiveness of the Venturis is typically between 90 and 100 percent. It increases with an increase in suction or suction pressure difference but decreases with an increase in total flow rate.(ii) The Venturi is most suitable for extraction of minute gas bubbles, especially for use with AP30 (whole blood), which yields substantially higher effectiveness than water.(iii) It is anticipated that a Venturi-aspirator unit can be superior to other bubble separation device as the cardiopulmonary bypass system for applications in extra corporeal blood oxygenation.

The Effect of Furosemide on the Intrarenal Blood Flow Distribution in the Dog

1972 ◽  
Vol 50 (8) ◽  
pp. 774-783 ◽  
Author(s):  
Serge Carrière ◽  
Michel Desrosiers ◽  
Jacques Friborg ◽  
Michèle Gagnan Brunette
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Urine Volume ◽  
Flow Distribution ◽  
Blood Flow Rate ◽  
Initial Distribution ◽  
Blood Flow Distribution ◽  
Intrarenal Blood Flow ◽  
Femoral Blood ◽  
Furosemide Administration

Furosemide (40 μg/min) was perfused directly into the renal artery of dogs in whom the femoral blood pressure was reduced (80 mm Hg) by aortic clamping above the renal arteries. This maneuver, which does not influence the intrarenal blood flow distribution, produced significant decreases of the urine volume, natriuresis, Ccreat, and CPAH, and prevented the marked diuresis normally produced by furosemide. Therefore the chances that systemic physiological changes occurred, secondary to large fluid movements, were minimized. In those conditions, however, furosemide produced a significant increase of the urine output and sodium excretion in the experimental kidney whereas Ccreat and CPAH were not affected. The outer cortical blood flow rate (ml/100 g-min) was modified neither by aortic constriction (562 ± 68 versus 569 ± 83) nor by the subsequent administration of furosemide (424 ± 70). The blood flow rate of the outer medulla in these three conditions remained unchanged (147 ± 52 versus 171 ± 44 versus 159 ± 54). The initial distribution of the radioactivity in each compartment remained comparable in the three conditions. In parallel with the results from the krypton-85 disappearance curves, the autoradiograms, silicone rubber casts, and EPAH did not suggest any change in the renal blood flow distribution secondary to furosemide administration.

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