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Sample records for blood pump development

  1. Engineering Aspects in Blood Pump Development

    NASA Technical Reports Server (NTRS)

    Golding, Leonard; Veres, Joseph P.

    1997-01-01

    NASA turbomachinery computer codes assisted in the design of the Cleveland Clinic Foundation's centrifugal bladed blood pump. The codes were originally developed for the aerospace industry, but are applicable to the blood pump because of a high degree of synergy with this application. Traditional turbomachinery design criteria were used in the design of the blood pump centrifugal impeller and volute casing. The fluid dynamic performance of the blood pump is meeting the engineering design goals of flow rate and pressure rise.

  2. Engineering Aspects in Blood Pump Development

    NASA Technical Reports Server (NTRS)

    Golding, Leonard; Veres, Joseph P.

    1997-01-01

    NASA turbomachinery computer codes assisted in the design of the Cleveland Clinic Foundation's centrifugal bladed blood pump. The codes were originally developed for the aerospace industry, but are applicable to the blood pump because of a high degree of synergy with this application. Traditional turbomachinery design criteria were used in the design of the blood pump centrifugal impeller and volute casing. The fluid dynamic performance of the blood pump is meeting the engineering design goals of flow rate and pressure rise.

  3. Development of an implantable centrifugal blood pump.

    PubMed

    Goldstein, A H; Pacella, J J; Trumble, D R; Clark, R E

    1992-01-01

    The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device.

  4. Rotary piston blood pumps: past developments and future potential of a unique pump type.

    PubMed

    Wappenschmidt, Johannes; Autschbach, Rüdiger; Steinseifer, Ulrich; Schmitz-Rode, Thomas; Margreiter, Raimund; Klima, Günter; Goetzenich, Andreas

    2016-08-01

    The design of implantable blood pumps is either based on displacement pumps with membranes or rotary pumps. Both pump types have limitations to meet the clinical requirements. Rotary piston blood pumps have the potential to overcome these limitations and to merge the benefits. Compared to membrane pumps, they are smaller and with no need for wear-affected membranes and valves. Compared to rotary pumps, the blood flow is pulsatile instead of a non-physiological continuous flow. Furthermore, the risk of flow-induced blood damage and platelet activation may be reduced due to low shear stress to the blood. The past developments of rotary piston blood pumps are summarized and the main problem for long-term application is identified: insufficient seals. A new approach with seal-less drives is proposed and current research on a simplified rotary piston design is presented. Expert commentary: The development of blood pumps focuses mainly on the improvement of rotary pumps. However, medical complications indicate that inherent limitations of this pump type remain and restrict the next substantial step forward in the therapy of heart failure patients. Thus, research on different pump types is reasonable. If the development of reliable drives and bearings succeeds, rotary piston blood pumps become a promising alternative.

  5. Performance of a newly developed implantable centrifugal blood pump.

    PubMed

    Tsukiya, T; Taenaka, Y; Tatsumi, E; Takano, H

    2001-01-01

    The performance of the newly developed implantable centrifugal blood pump was investigated in vitro. The pump was developed with the end goal of building a versatile system that includes a left ventricular assist system with an internal secondary battery or an implantable biventricular assist system with two implantable blood pumps. The hydrodynamic characteristics and efficiency of the blood pump were evaluated, and the mechanical damage to the blood caused by the blood pump was assessed through a hemolysis test using fresh goat blood. The pump could generate 120 mm Hg at a flow rate of 5 L/min and a motor speed of 2,500 rpm. The electric input power to the pump was approximately 5 watts under these working conditions. The hemolysis caused by the pump was a bit higher than that by the former model, but stayed within an acceptable range. Performance of the pump in vitro was considered sufficient for a left ventricular assist device, although further design improvement is necessary in terms of hemolysis and system efficiency to improve biocompatibility of the pump.

  6. Development of rotary blood pump technology: past, present, and future.

    PubMed

    Nosé, Y; Yoshikawa, M; Murabayashi, S; Takano, T

    2000-06-01

    Even though clinical acceptance of a nonpulsatile blood flow was demonstrated almost 45 years ago, the development of a nonpulsatile blood pump was completely ignored until 20 years ago. In 1979, the first author's group demonstrated that completely pulseless animals did not exhibit any abnormal physiology if 20% higher blood flows were provided to them. However, during the next 10 years (1979-1988), minimum efforts were provided for the development of a nonpulsatile, permanently implantable cardiac prosthesis. In 1989, the first author and his team at Baylor College of Medicine initiated a developmental strategy of various types of nonpulsatile rotary blood pumps, including a 2-day rotary blood pump for cardiopulmonary bypass application, a 2 week pump for ECMO and short-term circulatory assistance, a 2 year pump as a bridge to transplantation, and a permanently implantable cardiac prosthesis. Following the design and developmental strategy established in 1989, successful development of a 2-day pump (the Nikkiso-Fairway cardiopulmonary bypass pump) in 4 years (1989-1993), a 2 week pump (Kyocera gyro G1E3 pump) in 6 years (1992-1998), and a bridge to transplant pump (DeBakey LVAD-an axial flow blood pump) in 10 years (1988-1998) was made. Currently, a permanently implantable centrifugal blood pump development program is successfully completing its initial Phase 1 program of 5 years (1995-2000). Implantation exceeded 9 months without any negative findings. An additional 5 year Phase II program (2000-2005) is expected to complete such a device that will be clinically available.

  7. Development of a miniature intraventricular axial flow blood pump.

    PubMed

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. The spindle pump. Development of a nonpulsatile blood pump for assisted circulation.

    PubMed

    Hager, J; Brandstaetter, F; Koller, I; Unger, F

    1989-01-01

    The spindle pump is a combined working nonpulsatile blood pump, i.e., a centrifugally propelling device. This special concept was chosen to tackle the main problems of nonpulsatile pumps, such as thromboembolic complications, sealing difficulties, and traumatic hemolysis. The first two of these problems were relatively simple to solve compared with the third problem--traumatic hemolysis. Various modifications and constructive steps of the spindle pump were necessary to keep stress on blood components within adequate limits. The actual prototype--tested in three acute experiments and eight experiments with a longer pumping duration (the longest lasting 63 hours)--is described in extenso, and its development is discussed.

  9. Pitfalls in the development of a rotary blood pump controller.

    PubMed

    Konishi, H; Misawa, Y; Fuse, K; Sohara, Y

    2001-01-01

    The controller presents a major obstacle in the development of the rotary blood pump as a left ventricular assist device (LVAD). Clinically, LVAD flow is a good indicator in the regulation of circulatory conditions and pump flow changes, depending on pump preload and afterload. Many investigators have tried estimating pump flow by referencing the motor current. There have been pitfalls in in vitro experimental settings, however. Using a test loop with a pneumatically driven LV chamber and a centrifugal pump as an LVAD, we monitored pump flow and pressure head to evaluate the pump performance curve (H-Q curve). Under pulsatile LV conditions, the H-Q curve was a loop that changed, depending on LV contractility. The pneumatically driven LV chamber cannot mimic the Starling phenomenon, so the developed LV pressure does not change according to the LV preload. Rotary pump flow estimation is the most effective control method. In pulsatile conditions, however, the H-Q curve is a loop that changes under various LV contractility conditions, complicating determination of linear equation for calculating flow. In addition, the LV chamber in the test loop cannot mimic native heart contractility as described by Starling's law. This finding can lead to a misanalysis of the H-Q curve under pulsatile conditions.

  10. Blood Pump Development Using Rocket Engine Flow Simulation Technology

    NASA Technical Reports Server (NTRS)

    Kwak, Dochan; Kiris, Cetin

    2001-01-01

    This paper reports the progress made towards developing complete blood flow simulation capability in humans, especially in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed to quantify the flow in these devices such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological characterization of blood. As a first step, computational technology developed for aerospace applications was extended to the analysis and development of a ventricular assist device (VAD), i.e., a blood pump. The blood flow in a VAD is practically incompressible and Newtonian, and thus an incompressible Navier-Stokes solution procedure can be applied. A primitive variable formulation is used in conjunction with the overset grid approach to handle complex moving geometry. The primary purpose of developing the incompressible flow analysis capability was to quantify the flow in advanced turbopump for space propulsion system. The same procedure has been extended to the development of NASA-DeBakey VAD that is based on an axial blood pump. Due to massive computing requirements, high-end computing is necessary for simulating three-dimensional flow in these pumps. Computational, experimental, and clinical results are presented.

  11. Computational Approach for Developing Blood Pump

    NASA Technical Reports Server (NTRS)

    Kwak, Dochan

    2002-01-01

    This viewgraph presentation provides an overview of the computational approach to developing a ventricular assist device (VAD) which utilizes NASA aerospace technology. The VAD is used as a temporary support to sick ventricles for those who suffer from late stage congestive heart failure (CHF). The need for donor hearts is much greater than their availability, and the VAD is seen as a bridge-to-transplant. The computational issues confronting the design of a more advanced, reliable VAD include the modelling of viscous incompressible flow. A computational approach provides the possibility of quantifying the flow characteristics, which is especially valuable for analyzing compact design with highly sensitive operating conditions. Computational fluid dynamics (CFD) and rocket engine technology has been applied to modify the design of a VAD which enabled human transplantation. The computing requirement for this project is still large, however, and the unsteady analysis of the entire system from natural heart to aorta involves several hundred revolutions of the impeller. Further study is needed to assess the impact of mechanical VADs on the human body

  12. Blood Pump Development Using Rocket Engine Flow Simulation Technology

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin C.; Kwak, Dochan

    2002-01-01

    This viewgraph presentation provides information on the transfer of rocket engine flow simulation technology to work involving the development of blood pumps. Details are offered regarding the design and requirements of mechanical heart assist devices, or VADs (ventricular assist device). There are various computational fluid dynamics issues involved in the visualization of flow in such devices, and these are highlighted and compared to those of rocket turbopumps.

  13. Development of the pulsation device for rotary blood pumps.

    PubMed

    Yambe, Tomoyuki; Shiraishi, Yasuyuki; Sekine, Kazumitsu; Shibata, Mune-ichi; Yamaguchi, Tasuku; Jian, Liu Hong; Yoshizawa, Makoto; Tanaka, Akira; Matsuki, Hidetoshi; Sato, Fumihiro; Haga, You-ichi; Esashi, Masayoshi; Tabayashi, Kouichi; Mitamura, Yoshinori; Sasada, Hiroshi; Nitta, Shin-ichi

    2005-11-01

    A rotary blood pump (RP) is desirable as a small ventricular assist device (VAD). However, an RP is nonpulsatile. We tried to develop a device that attaches a pulse to the RP. We also tried to develop a pulse-generating equipment that was not air-pressure driven. The ball screw motor was considered a candidate. The application of a small-sized shape memory alloy was also attempted. An electrohydraulic system was adopted, and actuator power was connected to the diaphragm. The diaphragm was placed on the outer side of the ventricle. Most RPs that have been developed all over the world drain blood from the ventricle. The wave of a pulse should be generated if a pulse is added by the drawn part. The output assistance from the outer side of the ventricle was attempted in animal experiments, and the device operated effectively. This device can be used during implantable operation of RP. This may serve as an effective device in patients experiencing problems in peripheral circulation and in the function of internal organs.

  14. Development of a pump flow estimator for rotary blood pumps to enhance monitoring of ventricular function.

    PubMed

    Granegger, Marcus; Moscato, Francesco; Casas, Fernando; Wieselthaler, Georg; Schima, Heinrich

    2012-08-01

    Estimation of instantaneous flow in rotary blood pumps (RBPs) is important for monitoring the interaction between heart and pump and eventually the ventricular function. Our group has reported an algorithm to derive ventricular contractility based on the maximum time derivative (dQ/dt(max) as a substitute for ventricular dP/dt(max) ) and pulsatility of measured flow signals. However, in RBPs used clinically, flow is estimated with a bandwidth too low to determine dQ/dt(max) in the case of improving heart function. The aim of this study was to develop a flow estimator for a centrifugal pump with bandwidth sufficient to provide noninvasive cardiac diagnostics. The new estimator is based on both static and dynamic properties of the brushless DC motor. An in vitro setup was employed to identify the performance of pump and motor up to 20 Hz. The algorithm was validated using physiological ventricular and arterial pressure waveforms in a mock loop which simulated different contractilities (dP/dt(max) 600 to 2300 mm Hg/s), pump speeds (2 to 4 krpm), and fluid viscosities (2 to 4 mPa·s). The mathematically estimated pump flow data were then compared to the datasets measured in the mock loop for different variable combinations (flow ranging from 2.5 to 7 L/min, pulsatility from 3.5 to 6 L/min, dQ/dt(max) from 15 to 60 L/min/s). Transfer function analysis showed that the developed algorithm could estimate the flow waveform with a bandwidth up to 15 Hz (±2 dB). The mean difference between the estimated and measured average flows was +0.06 ± 0.31 L/min and for the flow pulsatilities -0.27 ± 0.2 L/min. Detection of dQ/dt(max) was possible up to a dP/dt(max) level of 2300 mm Hg/s. In conclusion, a flow estimator with sufficient frequency bandwidth and accuracy to allow determination of changes in ventricular contractility even in the case of improving heart function was developed.

  15. Development of a control algorithm for a rotary blood pump: prediction of recovery from cardiac failure.

    PubMed

    Konishi, H; Misawa, Y; Fuse, K

    1998-01-01

    Under extracorporeal membrane oxygenator (ECMO) support, it is difficult to predict recovery of cardiac function. The authors examined the rotary blood pump function curve and developed a new index of dynamic vascular impedance (DVI) for controlling the ECMO system. The cases of nine patients assisted by ECMO after cardiac surgery were analyzed. The index of DVI was calculated from the pump flow and the pressure difference (delta pressure) between the inlet and outlet of the pump. Seven patients were weaned from support. In the patients with recovery of cardiac function, the index of DVI was high and the delta pressure converged on the specific value. Analysis of the rotary blood pump function curve during ECMO support reflects the pump characteristics and provides data for the management of pump speed. The index of DVI can be used to predict the timing for weaning patients from ECMO support. The authors are developing an automatic control system that uses the index of DVI.

  16. Development of an implantable centrifugal blood pump for circulatory assist.

    PubMed

    Wakisaka, Y; Taenaka, Y; Chikanari, K; Okuzono, Y; Endo, S; Takano, H

    1997-01-01

    An implantable centrifugal pump (ICP) for prolonged circulatory assist has been developed, at 320 ml and 830 g. A central balancing hole was made in its impeller for better antithrombogenicity. Waterproofing and histocompatibility were supported by a silicone seal and a casing made of titanium and acrylic resin. Overall efficiency was 30% and normalized index of homolysis was 0.003 mg/dl, the same value as the BP-80, at a flow rate of 5 L/min and a head of 100 mmHg. Antithrombogenicity and hemolytic properties of the ICP were investigated in paracorporeal implantation in three goats (61-71 kg). Exothermicity, anatomic fit, and water tightness of the ICP were evaluated in intrathoracic implantation in an adult goat (66 kg). The ICP could run paracorporeally for 50, 200, and 381 days. There was no thrombus in the ICP after 381 days' pumping, and the ICP could run in the chest cavity for 40 days. The temperature of the motor rose 1.8 +/- 0.3 degrees C from that of the pleura. Moisture content of the seal remained normal. The ICP was completely covered with smooth fibrous tissue. Although a small area of atelectasis was found in the lingula, neither lung adhesion nor necrosis of the chest wall was observed. The ICP has satisfactory antithrombogenicity, hemolytic property, water tightness, anatomic fit, and exothermicity for use as an implantable circulatory assist device.

  17. Development of a magnetic fluid shaft seal for an axial-flow blood pump.

    PubMed

    Sekine, Kazumitsu; Mitamura, Yoshinori; Murabayashi, Shun; Nishimura, Ikuya; Yozu, Ryouhei; Kim, Dong-Wook

    2003-10-01

    A rotating impeller in a rotary blood pump requires a supporting system in blood, such as a pivot bearing or magnetic suspension. To solve potential problems such as abrasive wear and complexity of a supporting system, a magnetic fluid seal was developed for use in an axial-flow blood pump. Sealing pressures at motor speeds of up to 8,000 rpm were measured with the seal immersed in water or bovine blood. The sealing pressure was about 200 mm Hg in water and blood. The calculated theoretical sealing pressure was about 230 mm Hg. The seal remained perfect for 743 days in a static condition and for 180+ days (ongoing test) at a motor speed of 7,000 rpm. Results of measurement of cell growth activity indicated that the magnetic fluid has no negative cytological effects. The specially designed magnetic fluid shaft seal is useful for an axial-flow blood pump.

  18. Development of the Marseilles pulsatile rotary blood pump for permanent implantable left ventricular assistance.

    PubMed

    Montiès, J R; Havlik, P; Mesana, T; Trinkl, J; Tourres, J L; Demunck, J L

    1994-07-01

    We have developed a low-speed, double-lobed hypocycloidal pump that furnishes a pulsatile flow without valves. The pump is coupled to a specially designed electric motor. The motor/pump unit is totally implantable and has been extensively tested in vitro and in vivo in animals. Because this pump is volumetric, it is necessary to control speed precisely to avoid overpumping. Our control system, which is based on analysis of the motor current wave form, can detect and prevent negative pressures before they occur. The physical properties and hemocompatibility of several construction materials have been studied to determine their suitability for clinical use. These materials include a graphite substrate, titanium nitrate surface coating, boric carbon, and amorphous diamond. The pumps currently being tested are made of titanium, but clinical versions will be made of composite materials selected from this preliminary study. In vivo testing of this pump confirmed its good hemodynamic performance, low hemolysis rate, and biocompatibility (i.e., low heat, noise, and vibration levels). Animal experiments were terminated after 15 days because of mechanical failure related to the accumulation of blood components on moving parts. A new pump in which the mechanism is completely sealed from the blood flow has been designed and will soon be tested. If this sealed design is effective, the pump should be ready for use as a permanent implantable ventricular assistance device.

  19. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J. (Inventor); Akkerman, James W. (Inventor); Aber, Greg S. (Inventor); Vandamm, George A. (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1993-01-01

    A rotary blood pump is presented. The pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial, and radial clearances of the blades associated with the flow straightener, inducer portion, impeller portion, and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with crosslinked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  20. Development of a Compact Maglev Centrifugal Blood Pump Enclosed in a Titanium Housing

    NASA Astrophysics Data System (ADS)

    Pai, Chi Nan; Shinshi, Tadahiko; Asama, Junichi; Takatani, Setsuo; Shimokohbe, Akira

    A compact centrifugal blood pump consisting of a controlled two-degrees-of-freedom radial magnetic bearing and a brushless DC motor enclosed in a titanium housing has been developed for use as an implantable ventricular assist device. The magnetic bearing also supports axial and angular motions of the impeller via a magnetic coupling. The top housing is made of pure titanium, while the impeller and the stator are coated with pure titanium and Ti-6Al-7Nb, respectively, to improve the biocompatibility of the pump. The combination of pure titanium and titanium alloy was chosen because of the sensitivity of eddy current type displacement sensors through the intervening conducting wall. The dimensions of the pump are 69.0 mm in diameter and 28.5 mm in height. During a pump performance test, axial shifting of the impeller due to hydraulic forces led to variations in the rotational positioning signal, causing loss of control of the rotational speed. This problem was solved by conditioning the rotational positioning signal. With a flow rate of 5 l/min against a head pressure of 100 mmHg, the power consumption and efficiency of the pump were 5.5 W and 20%, respectively. Furthermore, the hemolysis of the blood pump was 43.6% lower when compared to that of a commercially available pump.

  1. Rotary Blood Pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George A. (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1996-01-01

    A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  2. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Benkowski, Robert J. (Inventor); Kiris, Cetin (Inventor); Kwak, Dochan (Inventor); Rosenbaum, Bernard J. (Inventor); Bacak, James W. (Inventor); DeBakey, Michael E. (Inventor)

    1999-01-01

    A blood pump that comprises a pump housing having a blood flow path therethrough, a blood inlet, and a blood outlet; a stator mounted to the pump housing, the stator having a stator field winding for producing a stator magnetic field; a flow straightener located within the pump housing, and comprising a flow straightener hub and at least one flow straightener blade attached to the flow straightener hub; a rotor mounted within the pump housing for rotation in response to the stator magnetic field, the rotor comprising an inducer and an impeller; the inducer being located downstream of the flow straightener, and comprising an inducer hub and at least one inducer blade attached to the inducer hub; the impeller being located downstream of the inducer, and comprising an impeller hub and at least one impeller blade attached to the impeller hub; and preferably also comprising a diffuser downstream of the impeller, the diffuser comprising a diffuser hub and at least one diffuser blade. Blood flow stagnation and clot formation within the pump are minimized by, among other things, providing the inducer hub with a diameter greater than the diameter of the flow straightener hub; by optimizing the axial spacing between the flow straightener hub and the inducer hub, and between the impeller hub and the diffuser hub; by optimizing the inlet angle of the diffuser blades; and by providing fillets or curved transitions between the upstream end of the inducer hub and the shaft mounted therein, and between the impeller hub and the shaft mounted therein.

  3. Centrifugal blood pumps for various clinical needs.

    PubMed

    Ichikawa, Seiji; Nosé, Yukihiko

    2002-11-01

    During the past 10 years, different types of blood pumps were developed to address various clinical needs. The Nikkiso centrifugal blood pump was developed for cardiopulmonary bypass application. This blood pump has been widely used in Japan in more than 20% of the cardiopulmonary bypass procedures. The Kyocera C1E3 Gryo pump was developed for short-term circulatory assistance and extracorporeal membrane oxygenation application for up to 2 weeks. This blood pump has been clinically used for up to 28 days without any blood clot formation. Through Phase I of the Japanese government New Energy and Industrial Technology Development Organization (NEDO) program, a chronically implanted centrifugal pump for left ventricular assistance was developed. This pump has already demonstrated its effectiveness, safety, and durability as a 2 year blood pump through in vitro and in vivo experiments. Currently, it is in the process of being converted from an experimental to a clinical device. Through Phase II of the NEDO program, a permanently implantable biventricular assist centrifugal blood pump system is under development. It has demonstrated that the previously mentioned left ventricular assist device blood pump is easily converted into a right ventricular assist pump by simply adding a spacer between the pump and the actuator. This communication discusses the historical development strategies for centrifugal blood pumps and their current status for different clinical needs.

  4. Development of a reliable automatic speed control system for rotary blood pumps.

    PubMed

    Vollkron, Michael; Schima, Heinrich; Huber, Leopold; Benkowski, Robert; Morello, Gino; Wieselthaler, Georg

    2005-11-01

    Axial blood pumps have been very successfully introduced into the arena of prolonged clinical support. However, they do not offer inherent load-responsive mechanisms for adjusting pumping performance to venous return and changes in physiologic requirements of the patient. To provide for these adjustments we developed an algorithm for demand-responsive pump control based on a reliable suction detection system. A PC-based system that analyzes pump performance based on available flow, heart rate and short-term performance history was developed. The physician defines levels of "desired flow" at rest and during exercise, depending on heart rate. In case this desired flow cannot be maintained due to limited venous return, the maximal available flow level is determined from an analysis of the actual pump data (flow, speed and power consumption). An expert system continuously checks the flow signal for any indication of suction. Periodic speed variations then adapt pump performance to the patient's condition. First, stability and functionality were proven under various settings in vitro. The algorithms were then tested in 15 patients in intensive care, in the standard ward, and during bicycle exercise. The system reacted properly to demand changes, at exercise level, in response to coughing and at various Valsalva maneuvers. Suction could also be successfully prevented during severe arrhythmia and in patients with critical cardiac geometry. Exercise tests showed decreases in pulmonary arterial pressure (-22 +/- 9.9%) and pulmonary capillary wedge pressure (-42 +/- 18.54%), and an increase in pump flow (19 +/- 9.5%) and workload (8 +/- 6.1%), all when compared with constant-speed pumping. A closed-loop control system equipped with an expert system for reliable suction detection was developed that improves response to change in venous return for rotary pump recipients. The system was robust, stable and safe under a wide range of everyday living conditions.

  5. Development of a closed air loop electropneumatic actuator for driving a pneumatic blood pump.

    PubMed

    Jeong, Gi Seok; Hwang, Chang Mo; Nam, Kyoung Won; Ahn, Chi Bum; Kim, Ho Chul; Lee, Jung Joo; Choi, Jaesoon; Son, Ho Sung; Fang, Yong Hu; Son, Kuk Hui; Lim, Choon Hak; Sun, Kyung

    2009-08-01

    In this study, we developed a small pneumatic actuator that can be used as an extracorporeal biventricular assist device. It incorporated a bellows-transforming mechanism to generate blood-pumping pressure. The cylindrical unit is 88 +/- 0.1 mm high, has a diameter of 150 +/- 0.1 mm, and weighs 2.4 +/- 0.01 kg. In vitro, maximal outflow at the highest pumping rate (PR) exceeded 8 L/min when two 55 mL blood sacs were used under an afterload pressure of 100 mm Hg. At a pumping rate of 100 beats per minute (bpm), maximal hydraulic efficiency was 9.34% when the unit supported a single ventricle and 13.8% when it supported both ventricles. Moreover, pneumatic efficiencies of the actuator were 17.3% and 33.1% for LVAD and BVAD applications, respectively. The energy equivalent pressure was 62.78 approximately 208.10 mm Hg at a PR of 60 approximately 100 bpm, and the maximal value of dP/dt during systole was 1269 mm Hg/s at a PR of 60 bpm and 979 mm Hg/s at a PR of 100 bpm. When the unit was applied to 15 calves, it stably pumped 3 approximately 4 L/min of blood at 60 bpm, and no mechanical malfunction was experienced over 125 days of operation. We conclude that the presently developed pneumatic actuator can be utilized as an extracorporeal biventricular assist device.

  6. Whole blood pumping with a microthrottle pump

    PubMed Central

    Davies, M. J.; Johnston, I. D.; Tan, C. K. L.; Tracey, M. C.

    2010-01-01

    We have previously reported that microthrottle pumps (MTPs) display the capacity to pump solid phase suspensions such as polystyrene beads which prove challenging to most microfluidic pumps. In this paper we report employing a linear microthrottle pump (LMTP) to pump whole, undiluted, anticoagulated, human venous blood at 200 μl min−1 with minimal erythrocyte lysis and no observed pump blockage. LMTPs are particularly well suited to particle suspension transport by virtue of their relatively unimpeded internal flow-path. Micropumping of whole blood represents a rigorous real-world test of cell suspension transport given blood’s high cell content by volume and erythrocytes’ relative fragility. A modification of the standard Drabkin method and its validation to spectrophotometrically quantify low levels of erythrocyte lysis by hemoglobin release is also reported. Erythrocyte lysis rates resulting from transport via LMTP are determined to be below one cell in 500 at a pumping rate of 102 μl min−1. PMID:21264059

  7. Development of the Baylor Gyro permanently implantable centrifugal blood pump as a biventricular assist device.

    PubMed

    Nonaka, K; Linneweber, J; Ichikawa, S; Yoshikawa, M; Kawahito, S; Mikami, M; Motomura, T; Ishitoya, H; Nishimura, I; Oestmann, D; Glueck, J; Schima, H; Wolner, E; Shinohara, T; Nosé, Y

    2001-09-01

    The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction

  8. Spiral blood pump: conception, development and clinical application of the original project.

    PubMed

    Dinkhuysen, Jarbas J; de Andrade, Aron José Pazin; Manrique, Ricardo; Saito, Claudia Sanches Medina; Leme, Juliana; Biscegli, Francisco

    2007-01-01

    This paper addresses an original project that encompasses the conception, development and clinical application of a helical bypass pump called the Spiral Pump, that uses the association of centrifugal and axial propulsion forces based de the Archimedes principle. This project has obtained a Brazilian Patent and an International Preliminary Report, defining it as an invention. The aim of this work was to evaluate the hemodynamic capacity and the impact of its application on blood cells by means of experimental in vitro tests, including hydrodynamic efficiency, effect on hemolysis and flow visualization. Moreover, in vivo experimental tests were carried out on lambs that were submitted to cardiopulmonary bypass for six hours and in 43 patients submitted to heart bypass surgery using the Spiral Pump. When the rotor-plastic casing gap was 1.5mm, the flow generated was nearly 9 L/min, the pressure was greater than 400 mmHg at 1500 rpm, and the normalized hemolytic indexes were not greater than 0.0375 g/100L in high-flow and pressure conditions. Additionally, by the flow visualization techniques, stagnation was not seen inside the pump nor was turbulence identified at the entrance or exit of the pump, or at the ends of the spindles. In the in vivo tests using cardiopulmonary bypasses for 6 hours in lambs, the pump maintained adequate pressure rates and the free hemoglobin levels ranged between 16.36 mg% and 44.90 mg%. Evaluating the results of the 43 patients who used this pump in heart bypass operations we observed that the free hemoglobin ranged from 9.34 mg% before to 44.16 mg% after surgery, the serum fibrinogen was from 236.65 mg% to 547.26mg%, platelet blood count from 152,465 to 98,139 and the lactic dehydrogenase from 238.12mg% to 547.26mg%. The Activated Coagulation Time was close to 800 seconds during the bypass. The Spiral Pump was very effective in generating adequate flow and pressure and caused no excessive harm to the blood cells.

  9. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  10. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  11. Turbine blood pumps.

    PubMed

    Noon, G P; Morley, D; Irwin, S; Abdelsayed, S; Benkowski, R; Lynch, B E

    2001-01-01

    After years of development and preclinical testing, clinical trials of the MicroMed DeBakey VAD began in November 1998 in Europe and in June 2000 in the United States. As of August 2000, 44 patients in Europe and 3 patients in the United States have undergone implantation with the MicroMed DeBakey VAD. In conclusion, data from the European clinical trial of the MicroMed DeBakey VAD support the safety and performance of the device. Results show that the device provides adequate left ventricular and circulatory support in patients with end-stage heart failure without unduly jeopardizing patient safety. Moreover, the device provides advantages not inherent to commercially available pulsatile devices: (1) miniature size, enabling implantation in smaller patients; (2) ease of implantation; (3) reduced surgical bleeding; and (4) a low incidence of postoperative infections, often a limiting factor with other devices. The MicroMed DeBakey VAD European clinical trial is the first demonstration of the compatibility of continuous blood flow with adequate tissue perfusion and overall maintenance of life for up to 4.5 months. This initial experience with the MicroMed DeBakey VAD suggests that the pump can provide circulatory support to bridge patients to cardiac transplantation and may provide an improved quality of life for the patient with end-stage heart failure.

  12. Development of magnetic bearing system for a new third-generation blood pump.

    PubMed

    Lee, Jung Joo; Ahn, Chi Bum; Choi, Jaesoon; Park, Jun Woo; Song, Seung-Joon; Sun, Kyung

    2011-11-01

    A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation

  13. Progress in the development of a transcutaneously powered axial flow blood pump ventricular assist system.

    PubMed

    Parnis, S M; Conger, J L; Fuqua, J M; Jarvik, R K; Inman, R W; Tamez, D; Macris, M P; Moore, S; Jacobs, G; Sweeney, M J; Frazier, O H

    1997-01-01

    Development of the Jarvik 2000 intraventricular assist system for long-term support is ongoing. The system integrates the Jarvik 2000 axial flow blood pump with a microprocessor based automatic motor controller to provide response to physiologic demands. Nine devices have been evaluated in vivo (six completed, three ongoing) with durations in excess of 26 weeks. Instrumented experiments include implanted transit-time ultrasonic flow probes and dual micromanometer LV/AoP catheters. Treadmill exercise and heart pacing studies are performed to evaluate control system response to increased heart rates. Pharmacologically induced cardiac dysfunction studies are performed in awake and anesthetized calves to demonstrate control response to simulated heart failure conditions. No deleterious effects or events were encountered during any physiologic studies. No hematologic, renal, hepatic, or pulmonary complications have been encountered in any study. Plasma free hemoglobin levels of 7.0 +/- 5.1 mg/dl demonstrate no device related hemolysis throughout the duration of all studies. Pathologic analysis at explant showed no evidence of thromboembolic events. All pump surfaces were free of thrombus except for a minimal ring of fibrin, (approximately 1 mm) on the inflow bearing. Future developments for permanent implantation will include implanted physiologic control systems, implanted batteries, and transcutaneous energy and data transmission systems.

  14. Development of a compact, sealless, tripod supported, magnetically driven centrifugal blood pump.

    PubMed

    Yuhki, A; Nogawa, M; Takatani, S

    2000-06-01

    In this study, a tripod supported sealless centrifugal blood pump was designed and fabricated for implantable application using a specially designed DC brushless motor. The tripod structure consists of 3 ceramic balls mounted at the bottom surface of the impeller moving in a polyethylene groove incorporated at the bottom pump casing. The follower magnet inside the impeller is coupled to the driver magnet of the motor outside the bottom pump casing, thus allowing the impeller to slide-rotate in the polyethylene groove as the motor turns. The pump driver has a weight of 230 g and a diameter of 60 mm. The acrylic pump housing has a weight of 220 g with the priming volume of 25 ml. At the pump rpm of 1,000 to 2,200, the generated head pressure ranged from 30 to 150 mm Hg with the maximum system efficiency being 12%. When the prototype pump was used in the pulsatile mock loop to assist the ventricle from its apex to the aorta, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics of the motor current power spectral density, was computed to possibly detect the suction occurring inside the ventricle due to the prototype centrifugal pump. When the WDI was kept under the value of 0.20 by adjusting the motor rpm, it was successful in suppressing the suction due to the centrifugal pump in the ventricle. The prototype sealless, centrifugal pump together with the control method based on the motor current waveform analysis may offer an intermediate support of the failing left or right ventricle bridging to heart transplantation.

  15. Current status of the gyro centrifugal blood pump--development of the permanently implantable centrifugal blood pump as a biventricular assist device (NEDO project).

    PubMed

    Nosé, Yukihiko; Furukawa, Kojiro

    2004-10-01

    The New Energy and Industrial Technology Development Organization (NEDO) project was started in 1995. The goal is the development of a multipurpose, totally implantable biventricular assist device (BVAD) that can be used for any patient who suffers from severe heart failure. Our C1E3 (two-week pump) centrifugal pump, called the Gyro pump, has three design characteristics: a magnetic coupling and double pivot bearing system, an eccentric inlet port, and secondary vanes on the bottom of the impeller. The pump was miniaturized. The C1E3 evolved into the NEDO PI-601, a totally implantable centrifugal pump for BVAD. The current NEDO PI-710 pump (five-year pump) system includes a centrifugal pump with pivot bearings, a hydraulically-levitated impeller, an rpm-controlled miniaturized actuator (all-in-one actuator plus controller), an emergency clamp on the left outflow, and a Frank-Starling-type flow control. The final mass production model is now finalized, and the final animal study and two-year endurance studies are ongoing.

  16. Mechanical drive for blood pump

    DOEpatents

    Bifano, N.J.; Pouchot, W.D.

    1975-07-29

    This patent relates to a highly efficient blood pump to be used as a replacement for a ventricle of the human heart to restore people disabled by heart disease. The mechanical drive of the present invention is designed to operate in conjunction with a thermoelectric converter power source. The mechanical drive system essentially converts the output of a rotary power into pulsatile motion so that the power demand from the thermoelectric converter remains essentially constant while the blood pump output is pulsed. (auth)

  17. Development of Lorentz force-type self-bearing motor for an alternative axial flow blood pump design.

    PubMed

    Lim, Tau Meng; Zhang, Dongsheng

    2006-05-01

    A Lorentz force-type self-bearing motor was developed to provide delivery of both motoring torque and levitation force for an alternative axial flow blood pump design with an enclosed impeller. The axial flow pumps currently available introduce electromagnetic coupling from the motor's stator to the impeller by means of permanent magnets (PMs) embedded in the tips of the pump's blades. This design has distinct disadvantages, for example, pumping efficiency and electromagnetic coupling transmission are compromised by the constrained or poor geometry of the blades and limited pole width of the PMs, respectively. In this research, a Lorentz force-type self-bearing motor was developed. It is composed of (i) an eight-pole PM hollow-cylindrical rotor assembly supposedly to house and enclose the impeller of an axial flow blood pump, and (ii) a six-pole stator with two sets of copper wire and different winding configurations to provide the motoring torque and levitating force for the rotor assembly. MATLAB's xPC Target interface hardware was used as the rapid prototyping tool for the development of the controller for the self-bearing motor. Experimental results on a free/simply supported rotor assembly validated the design feasibility and control algorithm effectiveness in providing both the motoring torque and levitation force for the rotor. When levitated, a maximum orbital displacement of 0.3 mm corresponding to 1050 rpm of the rotor was measured by two eddy current probes placed in the orthogonal direction. This design has the advantage of eliminating the trade-off between motoring torques, levitating force, and pumping efficiency of previous studies. It also indicated the benefits of enclosed-impeller design as having good dynamic response, linearity, and better reliability. The nonmechanical contact feature between rotating and stationary parts will further reduce hemolysis and thromboembolitic tendencies in a typical blood pump application.

  18. The valvo-pump. An axial, nonpulsatile blood pump.

    PubMed

    Mitamura, Y; Yozu, R; Tanaka, T; Yamazaki, K

    1991-01-01

    The valvo-pump, an axial, nonpulsatile blood pump implanted at the heart valve position while preserving diseased heart muscle, has several advantages over an artificial heart replacement, including 1) a good anatomic fit to the natural heart, 2) less blood contacting surface, and 3) ease of implantation. The housing for the pump is a tube, 37 mm in diameter (maximum) and 33 mm in length. Within the housing there is an impeller with either 10 vanes (33 mm in diameter) or 5 vanes (22 mm in diameter). The impeller is connected to a samarium-cobalt-rare-earth magnet direct current (DC) brushless motor measuring 23.8 mm in diameter and 30.2 mm in length. Sealing is achieved by means of a magnetic fluid seal. A guiding wheel with 4 vanes is located behind the impeller. The pump was studied on a hydraulic mock circulatory system to evaluate its performance characteristics. A pump flow of 6.9 L/min was obtained at a pump differential pressure of 48 mmHg, and flow of 3.1 L/min was obtained at 58 mmHg. The valvo-pump can be made feasible by developing a small, high-output, power motor and an endurable seal, as well as by optimizing the impeller design.

  19. Development of a miniaturized mass-flow meter for an axial flow blood pump based on computational analysis.

    PubMed

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-09-01

    In order to monitor the condition of patients with implantable left ventricular assist systems (LVAS), it is important to measure pump flow rate continuously and noninvasively. However, it is difficult to measure the pump flow rate, especially in an implantable axial flow blood pump, because the power consumption has neither linearity nor uniqueness with regard to the pump flow rate. In this study, a miniaturized mass-flow meter for discharged patients with an implantable axial blood pump was developed on the basis of computational analysis, and was evaluated in in-vitro tests. The mass-flow meter makes use of centrifugal force produced by the mass-flow rate around a curved cannula. An optimized design was investigated by use of computational fluid dynamics (CFD) analysis. On the basis of the computational analysis, a miniaturized mass-flow meter made of titanium alloy was developed. A strain gauge was adopted as a sensor element. The first strain gauge, attached to the curved area, measured both static pressure and centrifugal force. The second strain gauge, attached to the straight area, measured static pressure. By subtracting the output of the second strain gauge from the output of the first strain gauge, the mass-flow rate was determined. In in-vitro tests using a model circulation loop, the mass-flow meter was compared with a conventional flow meter. Measurement error was less than ±0.5 L/min and average time delay was 0.14 s. We confirmed that the miniaturized mass-flow meter could accurately measure the mass-flow rate continuously and noninvasively.

  20. A new blood pump for cardiopulmonary bypass: the HiFlow centrifugal pump.

    PubMed

    Göbel, C; Eilers, R; Reul, H; Schwindke, P; Jörger, M; Rau, G

    1997-07-01

    Centrifugal blood pumps are considered to be generally superior to the traditionally used roller pumps in cardiopulmonary bypass. In our institute a new lightweight centrifugal sealless blood pump with a unique spherical thrust bearing and with a magnetic coupling was developed, the HiFlow. The small design makes the pump suitable for applications in complex devices or close to a patient. Hemolysis tests were carried out in which the BioMedicus pump BP-80 and a roller pump were used as reference. The centrifugal pump HiFlow showed the least blood trauma within the group of investigated pumps. In summary, the HiFlow pump concept with its low priming volume and limited contact surfaces shows great potential for clinical applications in cardiopulmonary bypass. Also, the possibility of using the pump as a short-term assist device with an option of a pulsatile driving mode was demonstrated.

  1. Method for Reducing Pumping Damage to Blood

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Robert J. (Inventor); Benkowski, Robert J. (Inventor)

    1997-01-01

    Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed herein before. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

  2. Hemodialysis using a valveless pulsatile blood pump.

    PubMed

    Lee, Kyungsoo; Mun, Cho Hae; Lee, Sa Ram; Min, Byoung Goo; Yoo, Kyu Jae; Park, Yong Woo; Won, Yong Soon

    2008-01-01

    Research on pulsatile blood pumps for extracorporeal life support has been widely performed because of the proven advantageous effects of blood pulsation. However, studies on the use of pulsatile blood pumps for hemodialysis are limited, although available evidence demonstrates that pulsatile blood flow has a positive influence on dialysis outcome. Therefore, the authors designed a new pulsatile pump, which is characterized by minimal-occlusion of blood-containing tubing, no requirement for valves, and no blood flow regurgitation. In-vitro hemolysis tests were conducted using fresh bovine blood, and the normalized index of hemolysis was adopted to compare blood traumas induced by the devised pulsatile pump and a conventional roller pump. In addition, experimental hemodialyses with a canine renal failure model were performed using the devised pump. Normalized index of hemolysis levels obtained was much smaller for the devised pulse pump (45 +/- 21 mg/100 L) than for the roller pump (103 +/- 10 mg/100 L), and no technical problems were encountered during dialysis sessions. Blood and dialysate flow rates were maintained at predetermined values and molecular removal was satisfactory. Postdialysis urea and creatinine reduction ratios were 61.8% +/- 10.6% and 57.4% +/- 9.0%, respectively. Pulsatile flow has usually been generated using pulsatile devices containing valves, but the valves cause concern in terms of the clinical applications of these devices. However, the described pulsatile pump does not require valves, and yet no blood flow regurgitation was observed.

  3. A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential.

    PubMed

    Dame, Don

    1996-05-01

    Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required. © 1996 International Society for Artificial Organs.

  4. A teaspoon pump for pumping blood with high hydraulic efficiency and low hemolysis potential.

    PubMed

    Dame, D

    1996-06-01

    Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.

  5. Fluid Dynamics in Rotary Piston Blood Pumps.

    PubMed

    Wappenschmidt, Johannes; Sonntag, Simon J; Buesen, Martin; Gross-Hardt, Sascha; Kaufmann, Tim; Schmitz-Rode, Thomas; Autschbach, Ruediger; Goetzenich, Andreas

    2017-03-01

    Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid-structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

  6. Modeling of a rotary blood pump.

    PubMed

    Nestler, Frank; Bradley, Andrew P; Wilson, Stephen J; Timms, Daniel L

    2014-03-01

    The accurate representation of rotary blood pumps in a numerical environment is important for meaningful investigation of pump-cardiovascular system interactions. Although numerous models for ventricular assist devices (VADs) have been developed, modeling methods for rotary total artificial hearts (rTAHs) are still required. Therefore, an rTAH prototype was characterized in a steady flow, hydraulic test bench over a wide operational range for pump and hydraulic parameters. In order to develop a generic modeling method, a data-driven modeling approach was chosen. k-Nearest-neighbors, artificial neural networks, and support vector machines (SVMs) were the machine learning approaches evaluated. The best performing parameters for each algorithm were determined via optimization. The resulting multiple-input-multiple-output models were subsequently assessed under identical conditions, and a SVM with a radial basis function kernel was identified as the best performing. The achieved root mean squared errors were 0.03 L/min, 0.06 L/min, and 0.18 W for left and right flow and motor power consumption, respectively. In comparison with existing models for VADs, the flow errors are more than 70% lower. Further advantages of the SVM model are the robustness to measurement noise and the capability to operate outside of the trained parameter range. This proposed modeling method will accelerate further device refinements by providing a more appropriate numerical environment in which to evaluate the pump-cardiovascular system interaction.

  7. [Hemodynamic analysis of a centrifugal blood pump].

    PubMed

    Wang, Yang; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Li, Qilei; Xu, Liang

    2015-01-01

    This paper built the mathematical model of a centrifugal blood pump, which was designed by ourselves, combined it with that of the human cardiovascular system and simulated the coupling system using Matlab. Then we set up the experiment platform, linked the blood pump to mock human cardiovascular system in case of three-stage heart failure, and measured aortic pressure and flow under different speed. The comparison between experiment results and simulation results not only indicates the coupling model is correct and the blood pump works well, but also shows that with the increase of blood pump speed, the pulsation of aortic pressure and flow will be reduced, this situation will affect the structure and function of blood vessels.

  8. Fluid dynamics aspects of miniaturized axial-flow blood pump.

    PubMed

    Kang, Can; Huang, Qifeng; Li, Yunxiao

    2014-01-01

    Rotary blood pump (RBP) is a kind of crucial ventricular assist device (VAD) and its advantages have been evidenced and acknowledged in recent years. Among the factors that influence the operation performance and the durability of various rotary blood pumps, medium property and the flow features in pump's flow passages are conceivably significant. The major concern in this paper is the fluid dynamics aspects of such a kind of miniaturized pump. More specifically, the structural features of axial-flow blood pump and corresponding flow features are analyzed in detail. The narrow flow passage between blade tips and pump casing and the rotor-stator interaction (RSI) zone may exert a negative effect on the shear stress distribution in the blood flow. Numerical techniques are briefly introduced in view of their contribution to facilitating the optimal design of blood pump and the visualization of shear stress distribution and multiphase flow analysis. Additionally, with the development of flow measurement techniques, the high-resolution, effective and non-intrusive flow measurement techniques catering to the measurement of the flows inside rotary blood pumps are highly anticipated.

  9. Development of a disposable maglev centrifugal blood pump intended for one-month support in bridge-to-bridge applications: in vitro and initial in vivo evaluation.

    PubMed

    Someya, Takeshi; Kobayashi, Mariko; Waguri, Satoshi; Ushiyama, Tomohiro; Nagaoka, Eiki; Hijikata, Wataru; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2009-09-01

    MedTech Dispo, a disposable maglev centrifugal blood pump with two degrees of freedom magnetic suspension and radial magnetic coupling rotation, has been developed for 1-month extracorporeal circulatory support. As the first stage of a two-stage in vivo evaluation, 2-week evaluation of a prototype MedTech Dispo was conducted. In in vitro study, the pump could produce 5 L/min against 800 mm Hg and the normalized index of hemolysis was 0.0054 +/- 0.0008 g/100 L. In in vivo study, the pump, with its blood-contacting surface coated with biocompatible 2-methacryloyloxyethyl phosphorylcholine polymer, was implanted in seven calves in left heart bypass. Pump performance was stable with a mean flow of 4.49 +/- 0.38 L/min at a mean speed of 2072.1 +/- 64.5 rpm. The maglev control revealed its stability in rotor position during normal activity by the calves. During 2 weeks of operation in two calves which survived the intended study period, no thrombus formation was seen inside the pump and levels of plasma free hemoglobin were maintained below 4 mg/dL. Although further experiments are required, the pump demonstrated the potential for sufficient and reliable performance and biocompatibility in meeting the requirements for cardiopulmonary bypass and 1-week circulatory support.

  10. Development of design methods of a centrifugal blood pump with in vitro tests, flow visualization, and computational fluid dynamics: results in hemolysis tests.

    PubMed

    Takiura, K; Masuzawa, T; Endo, S; Wakisaka, Y; Tatsumi, E; Taenaka, Y; Takano, H; Yamane, T; Nishida, M; Asztalos, B; Konishi, Y; Miyazoe, Y; Ito, K

    1998-05-01

    There are few established engineering guidelines aimed at reducing hemolysis for the design of centrifugal blood pumps. In this study, a fluid dynamic approach was applied to investigate hemolysis in centrifugal pumps. Three different strategies were integrated to examine the relationship between hemolysis and flow patterns. Hemolytic performances were evaluated in in vitro tests and compared with the flow patterns analyzed by flow visualization and computational fluid dynamic (CFD). Then our group tried to establish engineering guidelines to reduce hemolysis in the development of centrifugal blood pumps. The commercially available Nikkiso centrifugal blood pump (HPM-15) was used as a standard, and the dimensions of 2 types of gaps between the impeller and the casing, the axial and the radial gap, were varied. Four impellers with different vane outlet angles were also prepared and tested. Representative results of the hemolysis tests were as follows: The axial gaps of 0.5, 1.0, and 1.5 mm resulted in normalized index of hemolysis (NIH) values of 0.0028, 0.0013 and 0.0008 g/100 L, respectively. The radial gaps of 0.5 and 1.5 mm resulted in NIH values of 0.0012 and 0.0008 g/100 L, respectively. The backward type vane and the standard one resulted in NIH values of 0.0013 and 0.0002 g/100 L, respectively. These results revealed that small gaps led to more hemolysis and that the backward type vane caused more hemolysis. Therefore, the design parameters of centrifugal blood pumps could affect their hemolytic performances. In flow visualization tests, vortices around the impeller outer tip and tongue region were observed, and their patterns varied with the dimensions of the gaps. CFD analysis also predicted high shear stress consistent with the results of the hemolysis tests. Further investigation of the regional flow patterns is needed to discuss the cause of the hemolysis in centrifugal blood pumps.

  11. Design of a Bearingless Blood Pump

    NASA Technical Reports Server (NTRS)

    Barletta, Natale; Schoeb, Reto

    1996-01-01

    In the field of open heart surgery, centrifugal blood pumps have major advantages over roller pumps. The main drawbacks to centrifugal pumps are however problems with the bearings and with the sealing of the rotor shaft. In this paper we present a concept for a simple, compact and cost effective solution for a blood pump with a totally magnetically suspended impeller. It is based on the new technology of the 'Bearingless Motor' and is therefore called the 'Bearingless Blood Pump.' A single bearingless slice motor is at the same time a motor and a bearing system and is able to stabilize the six degrees of freedom of the pump impeller in a very simple way. Three degrees of freedom are stabilized actively (the rotation and the radial displacement of the motor slice). The axial and the angular displacement are stabilized passively. The pump itself (without the motor-stator and the control electronics) is built very simply. It consists of two parts only: the impeller with the integrated machine rotor and the housing. So the part which gets in contact with blood and has therefore to be disposable, is cheap. Fabricated in quantities, it will cost less than $10 and will therefore be affordable for the use in a heart-lung-machine.

  12. In vivo evaluation of centrifugal blood pump for cardiopulmonary bypass-Spiral Pump.

    PubMed

    da Silva, Cibele; da Silva, Bruno Utiyama; Leme, Juliana; Uebelhart, Beatriz; Dinkhuysen, Jarbas; Biscegli, José F; Andrade, Aron; Zavaglia, Cecília

    2013-11-01

    The Spiral Pump (SP), a centrifugal blood pump for cardiopulmonary bypass (CPB), has been developed at the Dante Pazzanese Institute of Cardiology/Adib Jatene Foundation laboratories, with support from Sintegra Company (Pompeia, Brazil). The SP is a disposable pump with an internal rotor-a conically shaped fuse with double entrance threads. This rotor is supported by two ball bearings, attached to a stainless steel shaft fixed to the housing base. Worm gears provide axial motion to the blood column, and the rotational motion of the conically shaped impeller generates a centrifugal pumping effect, improving pump efficiency without increasing hemolysis. In vitro tests were performed to evaluate the SP's hydrodynamic performance, and in vivo experiments were performed to evaluate hemodynamic impact during usual CPB. A commercially available centrifugal blood pump was used as reference. In vivo experiments were conducted in six male pigs weighing between 60 and 90 kg, placed on CPB for 6 h each. Blood samples were collected just before CPB (T0) and after every hour of CPB (T1-T6) for hemolysis determination and laboratory tests (hematological and biochemical). Values of blood pressure, mean flow, pump rotational speed, and corporeal temperature were recorded. Also, ergonomic conditions were recorded: presence of noise, difficulty in removing air bubbles, trouble in installing the pump in the drive module (console), and difficulties in mounting the CPB circuit. Comparing the laboratory and hemolysis results for the SP with those of the reference pump, we can conclude that there is no significant difference between the two devices. In addition, reports made by medical staff and perfusionists described a close similarity between the two devices. During in vivo experiments, the SP maintained blood flow and pressure at physiological levels, consistent with those applied in cardiac surgery with CPB, without presenting any malfunction. Also, the SP needed lower rotational

  13. Piezohydraulic Pump Development

    NASA Technical Reports Server (NTRS)

    Lynch, Christopher S.

    2005-01-01

    Reciprocating piston piezohydraulic pumps were developed originally under the Smart Wing Phase II program (Lynch) and later under the CHAP program (CSA, Kinetic Ceramics). These pumps focused on 10 cm scale stack actuators operating below resonance and, more recently, at resonance. A survey of commercially available linear actuators indicates that obtaining power density and specific power greater than electromagnetic linear actuators requires driving the stacks at frequencies greater than 1 KHz at high fields. In the case of 10 cm scale actuators the power supply signal conditioning becomes large and heavy and the soft PZT stack actuators generate a lot of heat due to internal losses. Reciprocation frequencies can be increased and material losses significantly decreased through use of millimeter scale single crystal stack actuators. We are presently targeting the design of pumps that utilize stacks at the 1-10 mm length scale and run at reciprocating frequencies of 20kHz or greater. This offers significant advantages over current approaches including eliminating audible noise and significantly increasing the power density and specific power of the system (including electronics). The pump currently under development will comprise an LC resonant drive of a resonant crystal and head mass operating against a resonant fluid column. Each of these resonant systems are high Q and together should produce a single high Q second order system.

  14. Development of an Optical Detector of Thrombus Formation on the Pivot Bearing of a Rotary Blood Pump.

    PubMed

    Sakota, Daisuke; Fujiwara, Tatsuki; Ouchi, Katsuhiro; Kuwana, Katsuyuki; Yamazaki, Hiroyuki; Maruyama, Osamu

    2016-09-01

    Continuous optical monitoring of thrombus formation in extracorporeal mechanical circulatory support (EMCS) devices will contribute to safe, long-term EMCS. A clinically applicable optical detector must be able to distinguish among the optical characteristics of oxygen saturation (SaO2 ), hematocrit (Hct), and thrombus formation. In vitro studies of spectral changes at wavelengths from 400 to 900 nm associated with SaO2 , Hct, and thrombus formed around the top pivot bearing of a Gyro C1E3 pump were conducted. Fresh porcine blood anticoagulated with sodium citrate was circulated in a mock circuit using the pump. The SaO2 , Hct, and anticoagulation activity were altered using an oxygenator, autologous plasma, and calcium chlorite injection, respectively. Light from a xenon lamp was guided by an incident fiber perpendicularly fixed on the top bearing. This light was scattered by blood pooled between the male and female pivots. The detection fiber was perpendicularly fixed against the incident fiber, and the side-scattered light was detected and guided to a spectrophotometer. As a result, light at two different wavelengths, 420 and 810 nm, was identified as suitable for thrombus detection because it was negligibly influenced by SaO2 and was able to detect the optical characteristics of fibrin. The light at these two wavelengths responded more quickly to thrombus formation than the inlet or outlet pressure, and flow rate change. The optical changes showed the changes in Hct around the top pivot bearing, which is caused by the reduction in density of fibrin-trapped red blood cells (RBCs) due to the RBCs being swept away by the surrounding blood flow. The proposed method was also able to detect fibrin production by extracting subtle differences in the optical characteristics between the Hct and thrombus formation.

  15. Development of a novel centrifugal pump: magnetic rotary pump.

    PubMed

    Naganuma, S; Yambe, T; Sonobe, T; Kobayashi, S; Nitta, S

    1997-07-01

    The rotational axis of the centrifugal pump has some associated problems such as blood destruction and sealing between the axis and pump housing. To improve upon these deficits we have developed a new type of blood pump, the magnetic rotary pump (MRP). The MRP has an original design with no rotational axis and no impellers. We made a prototype MRP and examined its hemodynamics in mock circulation. The prototype MRP flow rate is only 1.0 L/min with an afterload of 30 mm Hg, and we have made some modifications in the size and drive mechanisms from these results. The modified MRP can achieve high flow rates and rotational speeds (6.0 L/min with an afterload of 100 mm Hg, 2,000 rpm) in a mock circuit, and the modified MRP was used for left heart assistance in an acute animal experiment. The MRP could maintain the hemodynamics of an anesthetized adult goat. These results suggest that the MRP needs to be improved in several areas, but the MRP may be useful as a blood pump.

  16. An implantable centrifugal blood pump for long term circulatory support.

    PubMed

    Yamazaki, K; Litwak, P; Kormos, R L; Mori, T; Tagusari, O; Antaki, J F; Kameneva, M; Watach, M; Gordon, L; Umezu, M; Tomioka, J; Koyanagi, H; Griffith, B P

    1997-01-01

    A compact centrifugal blood pump was developed as an implantable left ventricular assist system. The impeller diameter is 40 mm and the pump dimensions are 55 x 64 mm. This first prototype was fabricated from titanium alloy, resulting in a pump weight of 400 g including a brushless DC motor. Weight of the second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon to improve blood compatibility. Flow rates of over 7 L/min against 100 mmHg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system ("Cool-Seal") is used as a shaft seal. In this seal system, seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. The purge fluid is continuously purified and sterilized by an ultrafiltration filter incorporated into the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular apex-descending aorta bypass was performed utilizing a PTFE (Polytetrafluoroethylene) vascular graft, with the pump placed in the left thoracic cavity. In two in vivo experiments, pump flow rate was maintained at 5-8 L/min, and pump power consumption remained stable at 9-10 W. All plasma free hemoglobin levels were measured at < 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (< 0.5 ml/ day). Both animals remain under observation after 162 and 91 days of continuous pump function.

  17. Extracorporeal membrane oxygenator compatible with centrifugal blood pumps.

    PubMed

    Motomura, Tadashi; Maeda, Tomohiro; Kawahito, Shinji; Matsui, Takahiro; Ichikawa, Seiji; Ishitoya, Hiroshi; Kawamura, Masaki; Nishimura, Ikuya; Shinohara, Toshiyuki; Oestmann, Daniel; Glueck, Julia; Kawaguchi, Yoichiro; Sato, Koshiro; Nosé, Yukihiko

    2002-11-01

    Coil-type silicone membrane oxygenators can only be used with roller blood pumps due to the resistance from the high blood flow. Therefore, during extracorporeal membrane oxygenation (ECMO) treatment, the combination of a roller pump and an oxygenator with a high blood flow resistance will induce severe hemolysis, which is a serious problem. A silicone rubber, hollow fiber membrane oxygenator that has a low blood flow resistance was developed and evaluated with centrifugal pumps. During in vitro tests, sufficient gas transfer was demonstrated with a blood flow less than 3 L/min. Blood flow resistance was 18 mm Hg at 1 L/min blood flow. This oxygenator module was combined with the Gyro C1E3 (Kyocera, Japan), and veno-arterial ECMO was established on a Dexter strain calf. An ex vivo experiment was performed for 3 days with stable gas performance and low blood flow resistance. The combination of this oxygenator and centrifugal pump may be advantageous to enhance biocompatibility and have less blood trauma characteristics.

  18. Gas-heat-pump development

    SciTech Connect

    Creswick, F.A.

    1981-01-01

    Incentives for the development of gas heat pumps are discussed. Technical progress made on several promising technologies is reviewed. The status of development of gas-engine-driven heat pumps, the absorption cycle for the near- and long-term gas heat pump systems, the Stirling engine, the small Rankine-cycle engines, and gas-turbine-driven heat pump systems is briefly reviewed. Progress in the US, Japan, and Europe is noted. (MCW)

  19. Effects of scaling on centrifugal blood pumps.

    PubMed

    Wong, Yew Wah; Chan, Weng Kong; Yu, S C M; Chua, Leok Poh

    2002-11-01

    Experimental studies on the effects of scaling on the performance of centrifugal blood pumps were conducted in a closed-loop test rig. For the prototype, eight different impellers of the same outer diameter of 25 mm were tested at 1,500, 2,000, and 2,500 revolutions per minute (rpm) using blood analog as fluid medium. This corresponds to Reynolds numbers (Re) of 25,900, 34,500, and 43,200, respectively. The results indicated that the nondimensional pump characteristic is a function of Re. This is understandable since the typical operating Re for centrifugal blood pumps is less than 100,000. Thus, the effects of scaling cannot be ignored for centrifugal blood pumps. Experiments on a 5x scaled-up model have also indicated that the scaled-up model is more efficient than the prototype model. Our results showed that in the range of Re tested, the nondimensional head versus flow curve is a function of Re to the power of approximately 0.25. It is observed that the nondimensional head versus flow is a function of diameter ratio to the power of 0.2.

  20. Classification of physiologically significant pumping states in an implantable rotary blood pump: patient trial results.

    PubMed

    Karantonis, Dean M; Mason, David G; Salamonsen, Robert F; Ayre, Peter J; Cloherty, Shaun L; Lovell, Nigel H

    2007-01-01

    An integral component in the development of a control strategy for implantable rotary blood pumps is the task of reliably detecting the occurrence of left ventricular collapse due to overpumping of the native heart. Using the noninvasive pump feedback signal of impeller speed, an approach to distinguish between overpumping (or ventricular collapse) and the normal pumping state has been developed. Noninvasive pump signals from 10 human pump recipients were collected, and the pumping state was categorized as either normal or suction, based on expert opinion aided by transesophageal echocardiographic images. A number of indices derived from the pump speed waveform were incorporated into a classification and regression tree model, which acted as the pumping state classifier. When validating the model on 12,990 segments of unseen data, this methodology yielded a peak sensitivity/specificity for detecting suction of 99.11%/98.76%. After performing a 10-fold cross-validation on all of the available data, a minimum estimated error of 0.53% was achieved. The results presented suggest that techniques for pumping state detection, previously investigated in preliminary in vivo studies, are applicable and sufficient for use in the clinical environment.

  1. [Initial experience with a new blood pump].

    PubMed

    Margreiter, R; Schwab, W; Klima, G; Koller, J; Baum, M; Dietrich, H; Hager, J; Königsrainer, A

    1990-12-01

    A new type of blood pump was tested in calves for 6 hours. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotating on an eccentric shaft, describes a trochoidal path, thus creating a gap seal, the gap measuring a constant 10-35 microns. The pump is driven by a watercooled DC motor. For right ventricular assist, a cannula is inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assists. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 31 at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hours, and returned to 16 mg/dl after 6 hours. From these preliminary results it is concluded that this new rotary blood pump may be suitable as a circulatory assist device.

  2. Rotacor: a new rotary blood pump.

    PubMed

    Margreiter, R; Schwab, W; Klima, G; Koller, J; Baum, M; Dietrich, H; Hager, J; Königsrainer, A

    1990-01-01

    A new rotary blood pump was tested in calves for 6 hr. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotates on an eccentric shaft in a trochoidal path, thus creating a gap seal. The pump is driven by a water-cooled DC motor. For right ventricular assist, a cannula was inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assist. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 3 L at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hr, when it started to chop again; after 6 hr it was 16 mg/dl. From these preliminary results it is concluded that this new type of blood pump may be suitable as a circulatory assist device.

  3. Application of a magnetic fluid seal to rotary blood pumps.

    PubMed

    Mitamura, Y; Arioka, S; Sakota, D; Sekine, K; Azegami, M

    2008-05-21

    A magnetic fluid seal enables mechanical contact-free rotation of a shaft without frictional heat and material wear and hence has excellent durability. However, the durability of a magnetic fluid seal decreases in liquid. The life of a seal applied to a rotary blood pump is not known. We have developed a magnetic fluid seal that has a shield mechanism minimizing the influence of the rotary pump on the magnetic fluid. The developed magnetic fluid seal worked for over 286 days in a continuous flow condition, for 24 days (on-going) in a pulsatile flow condition and for 24 h (electively terminated) in blood flow. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps.

  4. Thermomechanical piston pump development

    NASA Technical Reports Server (NTRS)

    Sabelman, E. E.

    1971-01-01

    A thermally powered reciprocating pump has been devised to replace or augment an electric pump for the transport of temperature-control fluid on the Thermoelectric Outer Planet Spacecraft (TOPS). The thermally powered pump operates cyclically by extracting heat energy from the fluid by means of a vapor-pressure expansion system and by using the heat to perform the mechanical work of pumping. A feasibility test unit has been constructed to provide an output of 7 cu in during a 10- to 100-second cycle. It operates with a fluid input temperature of 200 to 300 F and a heat sink temperature of 0 to 30 F.

  5. Measurement of hemodynamic changes with the axial flow blood pump installed in descending aorta.

    PubMed

    Okamoto, Eiji; Yano, Tetsuya; Miura, Hidekazu; Shiraishi, Yasuyuki; Yambe, Tomoyuki; Mitamura, Yoshinori

    2017-09-08

    We have developed various axial flow blood pumps to realize the concept of the Valvo pump, and we have studied hemodynamic changes under cardiac assistance using an axial flow blood pump in series with the natural heart. In this study, we measured hemodynamic changes of not only systemic circulation but also cerebral circulation and coronary circulation under cardiac support using our latest axial flow blood pump placed in the descending aorta in an acute animal experiment. The axial flow blood pump was installed at the thoracic descending aorta through a left thoracotomy of a goat (43.8 kg, female). When the pump was on, the aortic pressure and aortic flow downstream of the pump increased with preservation of pulsatilities. The pressure drop upstream of the pump caused reduction of afterload pressure, and it may lead to reduction of left ventricular wall stress. However, cerebral blood flow and coronary blood flow were decreased when the pump was on. The axial flow blood pump enables more effective blood perfusion into systemic circulation, but it has the potential risk of blood perfusion disturbance into cerebral circulation and coronary circulation. The results indicate that the position before the coronary ostia might be suitable for implantation of the axial flow blood pump in series with the natural heart to avoid blood perfusion disturbances.

  6. A ferrofluidic seal specially designed for rotary blood pumps.

    PubMed

    Mitamura, Y; Fujiyoshi, M; Yoshida, T; Yozu, R; Okamoto, E; Tanaka, T; Kawada, S

    1996-06-01

    One of the key technologies required for rotary blood pumps is sealing of the motor shaft. A ferrofluidic seal was developed for an axial flow pump. The seal body was composed of a plastic magnet and two pole pieces. This seal was formed by injecting ferrofluid into the gap between the pole pieces and the motor shaft. To contain the ferrofluid in the seal and to minimize the possibility of ferrofluid making contact with blood, a shield with a small cavity was provided on the pole piece. Sealing pressure of the seal was measured. The sealing pressure was maintained at more than 23.3 kPa (175 mm Hg) for a motor speed up to 11,000 rpm. The specially designed ferrofluidic seal for sealing out liquids is useful for axial flow blood pumps.

  7. Intelligent pumping system developed

    SciTech Connect

    Not Available

    1983-06-01

    The oil field's first intelligent rod pumping system designed specifically to reduce the cost of pumping oil wells now is a reality. As a plus benefit, the system (called Liftronic) is compact and quiet. The new system combines an efficient mechanical design with a computer control system to reduce pumping costs. The unit stands less than 8 ft high, or approx. one-fourth the height of a comparable beam unit. It also mounts directly on the wellhead. The entire system can be concealed behind a fence or enclosed within a small building to make it a more attractive neighbor in residential, commercial, or recreational areas. It is useful also for agricultural areas where overhead irrigation systems restrict the use of many oil field pumping systems.

  8. Control and monitoring system for clinically employed pneumatic blood pumps.

    PubMed

    Normann, N A; Henrichsen, D W; Cooper, T G; King, R E; Noon, G P; DeBakey, M E

    1977-01-01

    Instantaneous position of the flexing member in pneumatic blood pumps is monitored on-line by measuring the electrical capacitance across the gas space within the pump. Monitor output is utilized in closed-loop pump control and for automatic pump shutdown in response to operational abnormalities. Thus, safety and efficacy are enhanced through operational optimization, automatic safety features, and facilitated evaluation.

  9. Inlet port positioning for a miniaturized centrifugal blood pump.

    PubMed

    Takano, Tamaki; Schulte-Eistrup, Sebastian; Kawahito, Shinji; Maeda, Tomohiro; Nonaka, Kenji; Linneweber, Joerg; Glueck, Julie; Fujisawa, Akira; Makinouchi, Kenzo; Yokokawa, Michihiro; Nosé, Yukihiko

    2002-01-01

    We are developing the Baylor-Kyocera KP implantable centrifugal blood pump for small sized adult and pediatric patients. This pump eccentrically positions the inlet port, which eliminates flow stagnation around the top pivot bearing. The inlet port design is important because it may vary the inlet orifice pressure on the top housing and change hydraulic performance and hemolytic characteristics. The pressure distribution inside the KP pump was assessed by a computational fluid dynamic (CFD) analysis with 2.7 x 10(5) elements and 3.16 x 10(5) nodes. Hydraulic performance and hemolysis were evaluated with 3 different pump housings, which had 3.8, 4.5, and 6.1 mm offset inlet ports from the center in a mock circuit. The CFD analysis revealed that the pressure gradually increased from the center toward the peripheral. The pressure difference between the 3.8 to 6.1 mm offsets was less than 600 Pa. The hydraulic performance did not drastically change at 3.8, 4.5, and 6.1 mm offset from the center. However, the hemolysis increased with the increase of the port offset from 0.0080+/- 0.0048 to 0.054 +/- 0.028 g/100 L. The inlet port positioning is important to attain less blood trauma in this small Gyro centrifugal blood pump. The preferable position of the inlet port is less than 4.5 mm offset from the center.

  10. Transformation of vibration signals in rotary blood pumps: the diagnostic potential of pump failure.

    PubMed

    Kawahito, Koji

    2013-09-01

    Although non-destructive and continuous monitoring is indispensable for long-term circulatory support with rotary blood pumps, a practical monitoring system has not yet been developed. The objective of this study was to investigate the possibility of detecting pump failure caused by thrombus formation through the monitoring of vibration signals. The data acquisition equipment included vibration pickups, a charge amplifier, vibration analysis systems, and exclusive hardware. A pivot-bearing centrifugal pump with a mock circuit was investigated for vibration analysis. To simulate the four common areas of thrombus formation, we used a piece of silicon attached to each of the following four locations: the total area of the bottom of the impeller, an eccentric shape on the bottom of the impeller, a circular shape around the shaft top, and an eccentric shape on the top of the impeller. Vibration signals were picked up, and the power spectrum density analysis was performed at pump rotational speeds of 2100, 2400, and 3000 rpm. In this study, pump failure could be detected, and the types of imitation thrombi could be determined. We conclude that vibration detection with a computerized analysis system is a potentially valuable diagnostic tool for long-term circulatory support with rotary blood pumps.

  11. Dynamic characteristics and mechatronics model for maglev blood pump

    NASA Astrophysics Data System (ADS)

    Sun, Kun; Chen, Chen

    2017-01-01

    Magnetic bearing system(MBs) has been developed in the new-generation blood pump due to its low power consumption, low blood trauma and high durability. However, MBs for a blood pump were almost influenced by a series of factors such as hemodynamics, rotation speeds and actuator response in working fluids, compared with those applied in other industrial fields. In this study, the dynamic characteristics of MBs in fluid environments, including the influence of the pumping fluid and rotation of the impeller on the radial dynamic model were investigated by measuring the frequency response to sinusoidal excitation upon coils, and the response of radial displacement during a raise in the speed. The excitation tests were conducted under conditions in which the blood pump was levitated in air and water and with or without rotation. The experimental and simulated results indicate that rotations of the impeller affected the characteristics of MBs in water apparently, and the vibration in water was decreased, compared with that in air due to the hydraulic force. During the start-up and rotation, the actuator failed to operate fully and timely, and the voltage supplied can be chosen under the consideration of the rotor displacement and consumption.

  12. A magnetically levitated centrifugal blood pump with a simple-structured disposable pump head.

    PubMed

    Hijikata, Wataru; Shinshi, Tadahiko; Asama, Junichi; Li, Lichuan; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2008-07-01

    A magnetically levitated centrifugal blood pump (MedTech Dispo) has been developed for use in a disposable extracorporeal system. The design of the pump is intended to eliminate mechanical contact with the impeller, to facilitate a simple disposable mechanism, and to reduce the blood-heating effects that are caused by motors and magnetic bearings. The bearing rotor attached to the impeller is suspended by a two degrees-of-freedom controlled radial magnetic bearing stator, which is situated outside the rotor. In the space inside the ringlike rotor, a magnetic coupling disk is placed to rotate the rotor and to ensure that the pump head is thermally isolated from the motor. In this system, the rotor can exhibit high passive stiffness due to the novel design of the closed magnetic circuits. The disposable pump head, which has a priming volume of 23 mL, consists of top and bottom housings, an impeller, and a rotor with a diameter of 50 mm. The pump can provide a head pressure of more than 300 mm Hg against a flow of 5 L/min. The normalized index of hemolysis of the MedTech Dispo is 0.0025 +/- 0.0005 g/100 L at 5 L/min against 250 mm Hg. This is one-seventh of the equivalent figure for a Bio Pump BPX-80 (Medtronic, Inc., Minneapolis, MN, USA), which has a value of 0.0170 +/- 0.0096 g/100 L. These results show that the MedTech Dispo offers high pumping performance and low blood trauma.

  13. Control of centrifugal blood pump based on the motor current.

    PubMed

    Iijima, T; Inamoto, T; Nogawa, M; Takatani, S

    1997-07-01

    In this study, centrifugal pump performance was examined in a mock circulatory loop to derive an automatic pump rotational speed (rpm) control method. The pivot bearing supported sealless centrifugal pump was placed in the left ventricular apex to aorta bypass mode. The pneumatic pulsatile ventricle was used to simulate the natural ventricle. To simulate the suction effect in the ventricle, a collapsible rubber tube was placed in the inflow port of the centrifugal pump in series with the apex of the simulated ventricle. Experimentally, the centrifugal pump speed (rpm) was gradually increased to simulate the suction effect. The pump flow through the centrifugal pump measured by an electromagnetic flowmeter, the aortic pressure, and the motor current were continuously digitized at 100 Hz and stored in a personal computer. The analysis of the cross-spectral density between the pump flow and motor current waveforms revealed that 2 waveforms were highly correlated at the frequency range between 0 and 4 Hz, with the coherence and phase angles being close to 1.0 and 0 degree, respectively. The fast Fourier transform analysis of the motor current indicated that the second harmonic component of the motor current power density increased with the occurrence of the suction effect in the circuit. The ratio of the fundamental to the second harmonic component decreased less than 1.3 as the suction effect developed in the circuit. It is possible to detect and prevent the suction effect of the centrifugal blood pump in the natural ventricle through analysis of the motor current waveform.

  14. Deformability of red blood cells and its relation to blood trauma in rotary blood pumps.

    PubMed

    Watanabe, Nobuo; Sakota, Daisuke; Ohuchi, Katsuhiro; Takatani, Setsuo

    2007-05-01

    In this study, mechanical trauma to red blood cells was evaluated by conventional hemolysis test and a newly developed cyclically reversing shear flow generator. The fresh porcine blood obtained from a local slaughterhouse was subjected to the conventional hemolysis test using a commercial centrifugal blood pump for the duration of 8 h. The measurements consisted of (i) plasma-free hemoglobin based on the standard optical measurement and (ii) the deformability of red blood cells (RBCs) using a cyclically reversing shear flow generator and microscope image acquisition system. The deformability of RBCs was expressed by the L/W value where L and W were the longer and shorter axes of the elongated RBCs' images. Although the plasma-free hemoglobin level increased with the pumping duration, the L/W remained unchanged for the duration of 8 h of pumping to indicate no alteration in the deformability. It was speculated that (i) although RBCs might have been circulated for so many times through the test pump, after each exposure to mechanical stress, RBCs might have recovered, and net effect due to shear stress-exposure time might have been small; and (ii) RBCs' deformability might be maintained near normal until sudden burst or membrane rupture, or the hemoglobin might have continuously leaked through the pores of the thinned membrane created by the mechanical stress. The deformability testing under a fluctuating shear flow could be a new method to quantify subhemolytic mechanical damage that has been accumulated in the RBCs' membrane and that may not be assessed by the conventional hemolysis test.

  15. Novel method to determine instantaneous blood volume in pulsatile blood pump using electrical impedance.

    PubMed

    Sasaki, E; Nakatani, T; Taenaka, Y; Takano, H; Hirose, H

    1994-08-01

    A novel real-time volumetric method was developed for a pulsatile pump. This method, the impedance method, used electrical impedance change in the blood chamber according to volume change while pumping. This method was evaluated with two kinds of air-driven diaphragm pumps. During in vitro tests, the impedance method indicated real-time volume change, and there was excellent correlation between computed stroke volume with the impedance method and measured stroke volume with the electromagnetic flowmeter. In chronic animal tests with goats and in a clinical case, the impedance method measured pump output accurately, and it detected diaphragm motion in real-time. In addition, excellent durability was seen. Full-fill to full-empty drive was realized accurately with this method. Application of the impedance method was easy, and it did not deteriorate native antithrombogencity of the pump. The impedance method is practical and useful to estimate the pumping condition of a pulsatile blood pump, especially a diaphragm pump. This method would be useful in clinical application.

  16. Computational fluid dynamics analysis of the pediatric tiny centrifugal blood pump (TinyPump).

    PubMed

    Kido, Kazuyuki; Hoshi, Hideo; Watanabe, Nobuo; Kataoka, Hiroyuki; Ohuchi, Katsuhiro; Asama, Junichi; Shinshi, Tadahiko; Yoshikawa, Masaharu; Takatani, Setsuo

    2006-05-01

    We have developed a tiny rotary centrifugal blood pump for the purpose of supporting circulation of children and infants. The pump is designed to provide a flow of 0.1-4.0 L/min against a head pressure of 50-120 mm Hg. The diameter of the impeller is 30 mm with six straight vanes. The impeller is supported by a hydrodynamic bearing at its center and rotated with a radial coupled magnetic driver. The bearing that supports rotation of the impeller of the tiny centrifugal blood pump is very critical to achieve durability, and clot-free and antihemolytic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify the secondary flow through the hydrodynamic bearing at the center of the impeller and investigated the effects of bearing clearance on shear stress to optimize hemolytic performance of the pump. Two types of bearing clearance (0.1 and 0.2 mm) were studied. The wall shear stress of the 0.1-mm bearing clearance was lower than that of 0.2-mm bearing clearance at 2 L/min and 3000 rpm. This was because the axial component of the shear rate significantly decreased due to the narrower clearance even though the circumferential component of the shear rate increased. Hemolysis tests showed that the normalized index of hemolysis was reduced to 0.0076 g/100 L when the bearing clearance was reduced to 0.1 mm. It was found that the CFD prediction supported the experimental trend. The CFD is a useful tool for optimization of the hydrodynamic bearing design of the centrifugal rotary blood pump to optimize the performance of the pump in terms of mechanical effect on blood cell elements, durability of the bearing, and antithrombogenic performance.

  17. Physiologic control algorithms for rotary blood pumps using pressure sensor input.

    PubMed

    Bullister, Edward; Reich, Sanford; Sluetz, James

    2002-11-01

    Hierarchical algorithms have been developed for enhanced physiologic control and monitoring of blood pumps using pressure inputs. Pressures were measured at pump inlet and outlet using APEX pressure sensors (APSs). The APS is a patented, long-term implantable, flow-through blood pressure sensor and designed to control implantable heart pumps. The algorithms have been tested using a Donavan circulatory mock-loop setup, a generic rotary pump, and LabVIEW software. The hierarchical algorithms control pump speed using pump inlet pressure as a primary independent variable and pump outlet pressure as a secondary dependent variable. Hierarchical control algorithms based on feedback from pressure sensors can control the speed of the pump to stably maintain ventricular filling pressures and arterial pressures. Monitoring algorithms based on pressure inputs are able to approximate flow rate and hydraulic power for the pump and the left ventricle.

  18. Design considerations of volute geometry of a centrifugal blood pump.

    PubMed

    Chan, Weng Kong; Wong, Yew Wah; Hu, Wei

    2005-12-01

    This article compares two different design techniques that are conventionally used in the design of volutes for centrifugal pumps. The imbalanced forces due to the geometry of the volute need to be taken into consideration especially in centrifugal blood pumps with magnetically suspended impeller. A reduction of these forces can reduce the instability of the impeller motion as well as the power needed to counteract its influence. Volutes using the constant angular momentum (CAM) and the constant mean velocity (CMV) methods were developed and modeled numerically. The computational results on the effect of volute geometry on the performance of a centrifugal blood pump impeller for six different volutes are presented here. For volutes designed using the CAM method, model B (volute expansion angle of 3 degrees ) had the lowest radial force of 0.26 N while the pressure head generated was 12,900 Pa. For volutes designed using the CMV method, model F (1.6 m/s) had the lowest imbalanced force of 0.45 N. However, the pressure developed by this pump was also one of the lowest at 10,652 Pa. Furthermore, when the peak scalar stresses and the mean exposure time of particles for all designs were determined using Lagrangian particle tracking method, it was observed that in general, the peak scalar stresses in CAM designed volutes are lower than those designed using CMV method. The mean exposure time of particles in the pump ranged from 400 to 500 ms. The simulation results showed that the volute designed using CAM method was superior to that of a CMV volute in terms of the magnitude of the radial force and the peak scalar stresses for the same pressure head generated. Results show that the design of volutes for blood pumps should go beyond conventional empirical methods to obtain optimal results.

  19. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2002-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  20. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2001-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  1. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2002-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  2. Blood Pump Having a Magnetically Suspended Rotor

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson J. (Inventor)

    2001-01-01

    A blood pump preferably has a magnetically suspended rotor that rotates within a housing. The rotor may rotate about a stator disposed within the housing. Radial magnetic bearings may be defined within the stator and the rotor in order to suspend the rotor. The radial magnetic bearings may be passive magnetic bearings that include permanent magnets disposed within the stator and the rotor or active magnetic bearings. The pump may further include an axial magnetic bearing that may be either a passive or an active magnetic bearing. A motor that drives the rotor may be disposed within the housing in order to more easily dissipate heat generated by the motor. A primary flow path is defined between the rotor and the stator, and a secondary flow path is defined between the stator and the rotor. Preferably, a substantial majority of blood passes through the primary flow path. The secondary flow path is large enough so that it provides adequate flushing of the secondary flow path while being small enough to permit efficient operation of the radial magnet bearings across the secondary flow path.

  3. [A review of drive system for pulsatile blood pump].

    PubMed

    Han, Yuan-jie; Yang, Ming

    2009-01-01

    Many varieties of pulsatile blood pumps exist in the fields of artificial hearts and ventricular assist devices. Effective sorts can be achieved with the differences in power source and transmission mechanism. Horizontal comparison across different pulsatile blood pumps, together with evolution of similar species is studied to find the commonness and evolution laws for pulsatile blood pumps. After a review of typical pulsatile blood pumps from the angle of power source and transmission mechanism, much analysis is focus on a pulsatile drive structure with flexible electro-hydraulic transmission, and importance of hydraulic transmission to improve the implantation property of pulsatile blood pumps is discussed. Finally new application of electro-hydraulic pulsatile blood pumps in the future, such as the application in Direct Mechanical Ventricular Assistant Device (DMVAD) is given.

  4. Identification and classification of physiologically significant pumping states in an implantable rotary blood pump.

    PubMed

    Karantonis, Dean M; Lovell, Nigel H; Ayre, Peter J; Mason, David G; Cloherty, Shaun L

    2006-09-01

    In a clinical setting it is necessary to control the speed of rotary blood pumps used as left ventricular assist devices to prevent possible severe complications associated with over- or underpumping. The hypothesis is that by using only the noninvasive measure of instantaneous pump impeller speed to assess flow dynamics, it is possible to detect physiologically significant pumping states (without the need for additional implantable sensors). By varying pump speed in an animal model, five such states were identified: regurgitant pump flow, ventricular ejection (VE), nonopening of the aortic valve over the cardiac cycle (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). These states are described in detail and a strategy for their noninvasive detection has been developed and validated using (n = 6) ex vivo porcine experiments. Employing a classification and regression tree, the strategy was able to detect pumping states with a high degree of sensitivity and specificity: state VE-99.2/100.0% (sensitivity/specificity); state ANO-100.0/100.0%; state PVC-I- 95.7/91.2%; state PVC-C-69.7/98.7%. With a simplified binary scheme differentiating suction (PVC-I, PVC-C) and nonsuction (VE, ANO) states, both such states were detected with 100% sensitivity.

  5. A multiple disk centrifugal pump as a blood flow device.

    PubMed

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.

  6. Development of a disposable magnetically levitated centrifugal blood pump (MedTech Dispo) intended for bridge-to-bridge applications--two-week in vivo evaluation.

    PubMed

    Nagaoka, Eiki; Someya, Takeshi; Kitao, Takashi; Kimura, Taro; Ushiyama, Tomohiro; Hijikata, Wataru; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2010-09-01

    Last year, we reported in vitro pump performance, low hemolytic characteristics, and initial in vivo evaluation of a disposable, magnetically levitated centrifugal blood pump, MedTech Dispo. As the first phase of the two-stage in vivo studies, in this study we have carried out a 2-week in vivo evaluation in calves. Male Holstein calves with body weight of 62.4–92.2 kg were used. Under general anesthesia, a left heart bypass with a MedTech Dispo pump was instituted between the left atrium and the descending aorta via left thoracotomy. Blood-contacting surface of the pump was coated with a 2-methacryloyloxyethyl phosphorylcholine polymer. Post-operatively, with activated clotting time controlled at 180–220 s using heparin and bypass flow rate maintained at 50 mL/kg/min, plasma-free hemoglobin (Hb), coagulation, and major organ functions were analyzed for evaluation of biocompatibility. The animals were electively sacrificed at the completion of the 2-week study to evaluate presence of thrombus inside the pump,together with an examination of major organs. To date, we have done 13 MedTech Dispo implantations, of which three went successfully for a 2-week duration. In these three cases, the pump produced a fairly constant flow of 50 mL/Kg/min. Neurological disorders and any symptoms of thromboembolism were not seen. Levels of plasma-free Hb were maintained very low. Major organ functions remained within normal ranges. Autopsy results revealed no thrombus formation inside the pump. In the last six cases, calves suffered from severe pneumonia and they were excluded from the analysis. The MedTech Dispo pump demonstrated sufficient pump performance and biocompatibility to meet requirements for 1-week circulatory support. The second phase (2-month in vivo study) is under way to prove the safety and efficacy of MedTech Dispo for 1-month applications.

  7. Development of Advanced Centrifugal Pumps

    SciTech Connect

    Rohatgi, U.

    2009-09-30

    A CRADA project was performed between BNL and Flowserve, California, under the auspices of Initiative for Proliferation Prevention (IPP) with the DOE support. The purpose was to jointly support a team of Russian institutes led by Kurchatov Institute to develop technology to increase operating life of centrifugal pumps. The work was performed from March 1, 2002 to September 30, 2009. The project resulted in development and validation the total cost of the sub-contract with Kurchatov Institute was $700,000, with matching fund from the industrial partner, Flowserve. The technical objective of this project is to develop advanced centrifugal pumps for the power, petroleum, chemical and water services industries by increasing the reliability of pumping equipment without a corresponding increase in life cycle cost. This major market need can be served by developing centrifugal pumps that generate only modest forces on the mechanical system even when operating under significant off-design conditions. This project is focused towards understanding the origin of hydraulic forces (both radial and axial, steady and time-dependent) and to develop design options, which reduce these forces over a broad flow range. This focus will include the force generation due to cavitation inside the pump as the operating conditions extend to low suction pressures. The results of research will reduce the inception of cavitation that leads to surface erosion and to find passive method of reducing peaks in axial thrust during whole range of flow rates.

  8. Miniaturization of a magnetically levitated axial flow blood pump.

    PubMed

    Cheng, Shanbao; Olles, Mark W; Olsen, Don B; Joyce, Lyle D; Day, Steven W

    2010-10-01

    This article introduces a unique miniaturization process of a magnetically levitated axial flow blood pump from a functional prototype to a pump suitable for animal trials. Through COMSOL three-dimensional finite element analysis and experimental verification, the hybrid magnetic bearings of the pump have been miniaturized, the axial spacing between magnetic components has been reduced, and excess material in mechanical components of the pump was reduced. Experimental results show that the pump performance was virtually unchanged and the smaller size resulted in the successful acute pump implantation in calves.

  9. [Centrifugal blood pumps (new possibilities of design improvement)].

    PubMed

    Leshchinskiĭ, B M; Itkin, G P; Zimin, N K

    1992-01-01

    Based on an analysis of 300 world information sources, 19 types of centrifugal blood pumps were ascertained. Five new designs suggested have an idea in common: combination of the inlet of the disk pump and of the outlet of the impeller pump. This allows uniting the merits of the above pumps and excluding their shortcomings. The designs suggested make it possible to solve the two basic problems: hemolysis and thrombogenesis inside the pumps. The use of the pumps designed on such a basis will afford a simple and reliable approach to heart function replacement.

  10. Design of a centrifugal blood pump: Heart Turcica Centrifugal.

    PubMed

    Demir, Onur; Biyikli, Emre; Lazoglu, Ismail; Kucukaksu, Suha

    2011-07-01

    A prototype of a new implantable centrifugal blood pump system named Heart Turcica Centrifugal (HTC) was developed as a left ventricular assist device (LVAD) for the treatment of end-stage cardiac failure. In the development of HTC, effects of blade height and volute tongue profiles on the hydraulic and hemolytic performances of the pump were investigated. As a result, the prototype was manufactured using the best blade height and volute tongue profiles. Performance of the prototype model was experimentally evaluated in a closed-loop flow system using water as the medium. The hydraulic performance requirement of an LVAD (5 L/min flow rate against a pressure difference of 100 mm Hg) was attained at 2800 rpm rotational speed.

  11. Condition monitoring of rotary blood pumps.

    PubMed

    Jammu, V B; Malanoski, S; Walter, T; Smith, W

    1997-01-01

    Long-term, trouble-free operation of ventricular assist devices (VADs) is critical to the patient. A catastrophic failure of the VAD could cost the patient's life, thus defeating the purpose of the device. The targeted 90% 5 year reliability also implies that the average device life would exceed the 5 year limit. Time based explantation of the device after the fifth year will replace many devices with significant additional life, subject the patient to unnecessary surgical risk, and increase costs. To preclude the need for time based replacements and prevent catastrophic failures, a condition monitor is proposed in this article for early detection of faults in VADs. To develop this monitor, the effectiveness of various sensing and monitoring methods for determining the VAD condition is investigated. A Hemadyne pump was instrumented with a set of eight sensors, and a series of experiments were performed to record and analyze signals from the normal and abnormal pumps with five different faults. Statistical, spectral, envelope, and ensemble averaging analyses were performed to characterize changes in sensor signals due to faults. Experimental results indicate that statistical and frequency information from the acceleration and dynamic pressure signals can clearly detect and identify various VAD faults.

  12. Noninvasive pulsatile flow estimation for an implantable rotary blood pump.

    PubMed

    Karantonis, Dean M; Cloherty, Shaun L; Mason, David G; Ayre, Peter J; Lovell, Nigel H

    2007-01-01

    A noninvasive approach to the task of pulsatile flow estimation in an implantable rotary blood pump (iRBP) has been proposed. Employing six fluid solutions representing a range of viscosities equivalent to 20-50% blood hematocrit (HCT), pulsatile flow data was acquired from an in vitro mock circulatory loop. The entire operating range of the pump was examined, including flows from -2 to 12 L/min. Taking the pump feedback signals of speed and power, together with the HCT level, as input parameters, several flow estimate models were developed via system identification methods. Three autoregressive with exogenous input (ARX) model structures were evaluated: structures I and II used the input parameters directly; structure II incorporated additional terms for HCT; and the third structure employed as input a non-pulsatile flow estimate equation. Optimal model orders were determined, and the associated models yielded minimum mean flow errors of 5.49% and 0.258 L/min for structure II, and 5.77% and 0.270 L/min for structure III, when validated on unseen data. The models developed in this study present a practical method of accurately estimating iRBP flow in a pulsatile environment.

  13. Magnetically suspended centrifugal blood pump with a self bearing motor.

    PubMed

    Masuzawa, Toru; Onuma, Hiroyuki; Kim, Seung-Jong; Okada, Yohji

    2002-01-01

    A magnetically suspended centrifugal blood pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semiopened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal blood pump is a candidate for an implantable left ventricular assist device.

  14. Implantable axialflow blood pump for left ventricular support.

    PubMed

    Untaroiu, Alexandrina; Wood, Houston G; Allaire, Paul E

    2008-01-01

    Artificial blood pumps, either ventricular assist devices (VADs) or total artificial hearts, are currently employed for bridge to recovery, bridge to transplant, and destination therapy situations. The clinical effectiveness of VADs has been demonstrated; however, all of the currently available pumps have a limited life because of either the damage they cause to blood or their limited mechanical design life. A magnetically suspended rotary blood pump offers the potential to meet the requirements of both extending design life and causing negligible blood damage due to superior hemodynamics. Therefore, over the last few years, efforts of an interdisciplinary research team at University of Virginia have been concentrated on the design and development of a fully implantable axial flow VAD with a magnetically levitated impeller (LEV-VAD). This paper details the second generation developmental prototype (LEV-VAD2 design configuration) and includes a complete CFD analysis of device performance. Based on encouraging results of the first design stage, including a good agreement between the CFD performance estimations and the experimental measurements, a second design phase was initiated in an attempt to enhance device flow performance and suspension system capabilities. Using iterative design optimization stages, the design of the impeller and the geometry of the stationary and rotating blades have been reevaluated. A thorough CFD analysis allowed for optimization of the blood flow path such that an optimal trade-off among the hydraulic performance, specific requirements of a blood pump, and manufacturing requirements has been achieved. Per the CFD results, the LEV-VAD2 produces 6 lpm and 100 mmHg at a rotational speed of 7,000 rpm. The pressure-flow performance predictions indicate the LEV-VAD2's ability to deliver adequate flow over physiologic pressures for rotational speeds varying from 5,000 to 8,000 rpm. The blood damage numerical predictions also demonstrate

  15. Development of novel ferrofluidic pumps.

    PubMed

    Andò, Bruno; Ascia, Alberto; Baglio, Salvatore; Pitrone, Nicola

    2006-01-01

    The development and realization of micropipettes and micropumps has captured the interest of people working in both biomedical and chemical areas for the capability of managing very low quantity of liquid (drug, biological liquid or expensive reagent) as well as everyone interested in controlling small flows for dedicated applications. In this paper a novel ferrofluidic pump adopting an electromagnetic actuation is proposed. The pump is realized by injecting three drops of ferrofluids into the pipe (two valves and a plunger are required) in the position where the pump must operate and by exploiting the forces produced onto each ferrofluid drop by some coils externally placed with respect to the pipe. The absence of any mechanical moving parts, the possibility to realize a volumetric pump in a section of an existing pipe without interruptions and deformation are the main advantages of the architecture proposed as compared to existing prototypes. A detailed description of the strategy proposed is presented along with a preliminary characterization of the prototype developed.

  16. Concept designs of nonrotating-type centrifugal blood pump and basic study on output characteristics of the oscillating disk-type centrifugal pump.

    PubMed

    Kabei, N; Tuichiya, K; Sakurai, Y

    1994-09-01

    When designing a turbo-type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating-type turbo pumps: a caudal-fin-type axial-flow pump, a caudal-fin-type centrifugal pump, a nutating-column-type centrifugal pump, a nutating-collapsible-tube-type centrifugal pump, and an oscillating-disk-type centrifugal pump. We selected and developed the oscillating-disk-type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high-speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i.e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16.9 ml. The performance of the pump was tested in a mock circulatory system.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Building a computer model of the Haemobear blood pump.

    PubMed

    Grönsfelder, Thomas; Schima, Heinrich; Reindl, Christian; Nordmann, Rainer

    2003-10-01

    Further development of the Haemobear blood pump requires theoretical predictions of the dynamic behavior of the rotor. These predictions can be used to compare different rotor geometry at desired operating conditions before a prototype is built. The study focuses on a rotor-dynamic model of the rigid rotor with six degrees of freedom (6-DoF), which is implemented using the Matlab-Simulink software package. The forces acting on the rotor are provided to Simulink in terms of constant values (e.g., gravity force), linear coefficients, or nonlinear functions. These coefficients or functions are obtained using numerical simulation results. Fluid forces and magnetic forces can be calculated using commercial software codes. The output of these codes has to be postprocessed to get the desired values for Simulink. This article will give an overview of how to implement arbitrary physical influences on the rotor in a computational model of the complete pump.

  18. [Research on flow characteristics in a non-blade centrifugal blood pump based on CFD technology].

    PubMed

    Cheng, Yunzhang; Luo, Binhai; Wu, Wenquan; Jiang, Lei

    2010-10-01

    The problem of thrombus and hemolysis in blood pump has always been an important topic to study in the development of the blood pump. Numbers of research results show that it is the complicated flow and the high shear stress of the mechanical movement that result in the thrombus and hemolysis. In this study, with the cooperation of Shanghai Children's Medical Center, we have used computational fluid dynamics (CFD) commercial software FLUENT to compute and analyze the flow characteristics in a non-blade centrifugal blood pump. The results figure out that this pump has a reasonable flow distribution and the shear stress distribution is under the critical broken state of red blood cell; meanwhile, there is less thrombus and hemolysis in this pump. So it is in the foreground for clinical use.

  19. An electromagnetic pneumatic blood pump driver.

    PubMed

    Whalen, R L; Briskman, R N

    1988-01-01

    An electromagnetic pneumatic pump driver has been developed with the goals of enhanced mechanical reliability and simplicity of operation. The new driver eliminates failure prone components such as solenoid valves or pressure regulators common to conventional pneumatic drive systems, has only a single moving part, and provides for closed-loop operation in which stroke volume and dP/dT are controlled on each beat in real time. Power is provided by a high force (178 N) electromagnetic linear actuator. This assembly uses a high energy density neodymium-iron-boron permanent magnet, low loss vanadium alloy pole pieces, and an energized moving coil. The nominal stroke length of the actuator is 1.7 cm. During operation, the moving coil always remains within a fixed annular air gap, resulting in a measured force output versus applied power linearity of better than 92% over its stroke range. The coil is directly attached to the free end of a 10 cm diameter, 21 convolution, welded titanium metal bellows that forms the gas containing element of the system. The comparatively low pressure gradients across the bellows in this application result in a predicted life for the bellows in excess of 10(9) cycles. Bellows position and internal pressure are monitored continuously to control the pneumatic output. The linear actuator total excursion and velocity are adjusted on each beat using a closed-loop servo system. This results in a pump driver with no operator required adjustment of drive pressure. Instead, there are user selected settings of stroke volume, operating mode, and fill sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Induction of ventricular collapse by an axial flow blood pump.

    PubMed

    Amin, D V; Antaki, J F; Litwak, P; Thomas, D; Wu, Z J; Watach, M

    1998-01-01

    An important consideration for clinical application of rotary blood pump based ventricular assist is the avoidance of ventricular collapse due to excessive operating speed. Because healthy animals do not typically demonstrate this phenomenon, it is difficult to evaluate control algorithms for avoiding suction in vivo. An acute hemodynamic study was thus conducted to determine the conditions under which suction could be induced. A 70 kg calf was implanted with an axial flow assist device (Nimbus/UoP IVAS; Nimbus Inc., Rancho Cordova, CA) cannulated from the left ventricular apex to ascending aorta. On initiation of pump operation, several vasoactive interventions were performed to alter preload, afterload, and contractility of the left ventricle. Initially, dobutamine increased contractility and heart rate ([HR] = 139; baseline = 70), but ventricular collapse was not achievable, even at the maximal pump speed of 15,000 rpm. Norepinephrine decreased HR (HR = 60), increased contractility, and increased systemic vascular resistance ([SVR] = 24; baseline = 15), resulting in ventricular collapse at a pump speed of 14,000 rpm. Isoproterenol (beta agonist) increased HR (HR = 103) and decreased SVR (SVR = 12), but ventricular collapse was not achieved. Inferior vena cava occlusion reduced preload, and ventricular collapse was achieved at speeds as low as 11,000 rpm. Esmolol (beta1 antagonist) decreased HR (HR = 55) and contractility, and ventricular collapse was achieved at 11,500 rpm. Episodes of ventricular collapse were characterized initially by the pump output exceeding the venous return and the aortic valve remaining closed throughout the cardiac cycle. If continued, the mitral valve would remain open throughout the cardiac cycle. Using these unique states of the mitral and aortic valves, the onset of ventricular collapse could reliably be identified. It is hoped that the ability to detect the onset of ventricular collapse, rather than the event itself, will assist in

  1. The valvo-pump, an axial blood pump implanted at the heart valve position: concept and initial results.

    PubMed

    Yamazaki, K; Okamoto, E; Yamamoto, K; Mitamura, Y; Tanaka, T; Yozu, R

    1992-06-01

    The valvo-pump, an axial nonpulsatile blood pump implanted at the heart valve position, has been developed. The valvo-pump consists of an impeller and a motor, which are encased in a housing. An impeller with 5 vanes (22.0 mm in diameter) is used. The impeller is connected to a samarium-cobalt-rare earth magnet direct current (DC) brushless motor measuring 21.3 mm in diameter and 18.5 mm in length. Sealing is achieved by means of a ferrofluidic seal. A pump flow of 10.5 L/min was obtained at a pump differential pressure of 3.3 kPa (25 mm Hg), and a flow of 4.9 L/min was obtained at 7.0 kPa (53 mm Hg). Sealing was kept perfect against a pressure of 29.3 kPa (220 mm Hg) at 9,000 rpm.

  2. In vitro investigation of thrombogenesis in rotary blood pumps.

    PubMed

    Schima, H; Siegl, H; Mohammad, S F; Huber, L; Müller, M R; Losert, U; Thoma, H; Wolner, E

    1993-07-01

    Thrombus formation at sealing and stagnation areas remains a major problem in the development of rotary blood pumps. Until now, the complex phenomena could only be studied in vivo. In this study, an in vitro mock circulation previously used for hemolysis studies was adapted for thrombosis evaluation. Blood was collected in the slaughterhouse with strict avoidance of air contact and was heparinized (1.5 U heparin/ml blood; activated coagulation time [ACT]: initially, 140-180 s; after collection, 400-600 s). During the test, the ACT decreased gradually. The tests were stopped after 90 to 180 min at an ACT of 1.5 times the initial value. Thrombus formation was observed at the same locations as observed in left-heart assist devices (sealing area, connecting bolts, and stagnant water areas at connectors). The thrombi were similar in shape, color, and histology to those found after 2 to 4 days in vivo. This test provides a valuable tool for evaluating thrombus formation in prototypes and screening tests of different rotary pump designs.

  3. The role of diastolic pump flow in centrifugal blood pump hemodynamics.

    PubMed

    Akimoto, T; Litwak, K N; Yamazaki, K; Litwak, P; Kihara, S I; Tagusari, O; Yamazaki, S I; Kameneva, M V; Watach, M J; Umezu, M; Tomioka, J; Kormos, R L; Koyanagi, H; Griffith, B P

    2001-09-01

    We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventricular (LV) output during systole. A calf (80 kg) was implanted with an implantable centrifugal blood pump (EVAHEART, SunMedical Technology Research Corp., Nagano, Japan) with left ventricle to aorta (LV-Ao) bypass, and parameters were recorded at different pump speeds under general anesthesia. Pump inflow and outflow pressure, arterial pressure, systemic and pulmonary blood flow, and electrocardiogram (ECG) were recorded on the computer every 5 ms. All parameters were separated into systolic and diastolic components and analyzed. The pulmonary flow was the same as the systemic flow during the study (p > 0.1). Systemic flow consisted of pump flow and LV output through the aortic valve. The ratio of systolic pump flow to pulmonary flow (51.3%) did not change significantly at variable pump speeds (p > 0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When pump flow increased during diastole, there was a corresponding decrease in the LV output (Y = -1.068X + 51.462; R(insert)(2) = 0.9501). These show that pump diastolic flow may regulate expansion of the left ventricle in diastole.

  4. Experimental Fluid Mechanics of Pulsatile Artificial Blood Pumps

    NASA Astrophysics Data System (ADS)

    Deutsch, Steven; Tarbell, John M.; Manning, Keefe B.; Rosenberg, Gerson; Fontaine, Arnold A.

    2006-01-01

    The fluid mechanics of artificial blood pumps has been studied since the early 1970s in an attempt to understand and mitigate hemolysis and thrombus formation by the device. Pulsatile pumps are characterized by inlet jets that set up a rotational "washing" pattern during filling. Strong regurgitant jets through the closed artificial heart valves have Reynolds stresses on the order of 10,000 dynes/cm2 and are the most likely cause of red blood cell damage and platelet activation. Although the flow in the pump chamber appears benign, low wall shear stresses throughout the pump cycle can lead to thrombus formation at the wall of the smaller pumps (10 50 cc). The local fluid mechanics is critical. There is a need to rapidly measure or calculate the wall shear stress throughout the device so that the results may be easily incorporated into the design process.

  5. Computational Fluid Dynamics-Based Design Optimization Method for Archimedes Screw Blood Pumps.

    PubMed

    Yu, Hai; Janiga, Gábor; Thévenin, Dominique

    2016-04-01

    An optimization method suitable for improving the performance of Archimedes screw axial rotary blood pumps is described in the present article. In order to achieve a more robust design and to save computational resources, this method combines the advantages of the established pump design theory with modern computer-aided, computational fluid dynamics (CFD)-based design optimization (CFD-O) relying on evolutionary algorithms and computational fluid dynamics. The main purposes of this project are to: (i) integrate pump design theory within the already existing CFD-based optimization; (ii) demonstrate that the resulting procedure is suitable for optimizing an Archimedes screw blood pump in terms of efficiency. Results obtained in this study demonstrate that the developed tool is able to meet both objectives. Finally, the resulting level of hemolysis can be numerically assessed for the optimal design, as hemolysis is an issue of overwhelming importance for blood pumps.

  6. An original versatile nonocclusive pressure-regulated blood roller pump for extracorporeal perfusion.

    PubMed

    Durandy, Yves; Wang, Shigang; Ündar, Akif

    2014-06-01

    Currently, only a small number of centrifugal pumps are being used for hemodynamic and/or respiratory support, but all of them have limitations. This article aims to present the Rhône-Poulenc 06 nonocclusive pressure-regulated blood pump. This pump was developed in France in the 1970s and used for decades in perfusion for cardiopulmonary bypass procedures, cardiac or lung assist as well as venovenous bypass during liver transplant. The intrinsic properties of this pump allowed us to describe a new technique for extracorporeal lung support in the 1980s, using a single cannula tidal flow venovenous bypass. This pump compared favorably with conventional pumps in terms of flow and pressure, hemolysis, pulsatility, safety, and cost-effectiveness. We believe that this simple pump could be an alternative to more sophisticated and expensive devices.

  7. Multivariate Assessment of the Effect of Pump Design and Pump Gap Design Parameters on Blood Trauma.

    PubMed

    Graefe, Roland; Henseler, Andreas; Steinseifer, Ulrich

    2016-06-01

    Pump gaps are the most critical regions in a rotary blood pump when it comes to blood trauma in the form of hemolysis, protein destruction, and platelet activation. This study investigated six pump design parameters affecting the flow in a radial pump gap. A multivariate approach was employed to determine individual and quantitative parameter effects on blood trauma as well as parameter interactions. To consider the effect of shear stress and blood cell residence time, a validated numerical Lagrangian particle tracking approach was used. Based on the results, small-diameter pumps can be as blood compatible, if not more blood compatible, as large-diameter pumps as long as identical circumferential velocities and clearance gaps are maintained. Furthermore, the results indicate that an eccentric rotor position in the casing is not harmful and that a pressure difference generating washout flow and thereby reducing the cell residence time is of significant importance. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  8. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  9. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  10. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  11. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  12. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  13. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  14. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  15. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  16. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through...

  17. 21 CFR 870.4360 - Nonroller-type cardiopulmonary bypass blood pump.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nonroller-type cardiopulmonary bypass blood pump... Nonroller-type cardiopulmonary bypass blood pump. (a) Identification. A nonroller-type cardiopulmonary bypass blood pump is a device that uses a method other than revolving rollers to pump the blood...

  18. A review of leakage flow in centrifugal blood pumps.

    PubMed

    Chan, Weng-Kong; Wong, Yew-Wah

    2006-05-01

    This article presents a new approach in determining the functional relationship between the leakage flow in a centrifugal blood pump and various parameters that affect it. While high leakage flow in a blood pump is essential for good washout and can help prevent thrombus formation, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Dimensional analysis is employed to provide a functional relationship between leakage flow rate and other important parameters governing the operation of a centrifugal blood pump. Results showed that pump performance with a smaller gap clearance is clearly superior compared to those of two other similar pumps with larger gap clearances. It was also observed that the nondimensional leakage flow rate varies almost linearly with dimensionless pump head. It also decreases with increasing volume flow rate. A smaller gap clearance will also increase the flow resistance and hence, decrease the nondimensional leakage flow rate. Increasing surface roughness, length of the gap clearance passage, or loss coefficient of the gap geometry will increase losses and hence, decrease the leakage flow rate. It is also interesting to note that for a given pump and gap clearance geometry, the nondimensional leakage flow rate is almost independent of the Reynolds number when specific speed is constant.

  19. Continuous Monitoring of Aortic Valve Opening in Rotary Blood Pump Patients.

    PubMed

    Granegger, Marcus; Masetti, Marco; Laohasurayodhin, Ravi; Schloeglhofer, Thomas; Zimpfer, Daniel; Schima, Heinrich; Moscato, Francesco

    2016-06-01

    Rotary blood pumps (RBPs) typically support the left ventricle by pumping blood from the ventricle to the aorta, partially bypassing the aortic valve (AV). Monitoring the AV opening during RBP support would provide important information about cardiac-pump interaction. However, currently this information is not continuously available. In this study, an algorithm to determine AV opening using available pump signals was evaluated in humans. Pump speed changes were performed in 15 RBP patients to elicit opening of the AV. Simultaneously to pump data recordings, the AV was continuously monitored using echocardiography. The algorithm, which classifies the AV state utilizing three features (skewness, kurtosis, and crest factor) calculated from the pump flow waveform, was compared to echocardiography by using cross-validation analysis. Additionally, numerical simulation was used to evaluate effects of different pump characteristics and cannula length, as well as mitral valve insufficiency on the AV opening detection method. More than 7000 heart beats were analyzed. The correct classification rate using the developed algorithm was 91.1% (sensitivity 91.0%, specificity 91.2%). Numerical simulations showed that the flow waveform shape used for AV opening detection is preserved under the different conditions studied. This study demonstrates that the AV opening can be reliably detected in RBP patients using available pump data. Once implemented in RBP controllers, this method will provide a novel tool to improve the management of RBP patients, particularly for adjustments of the pump speed and flow and for the evaluation of the assisted cardiac function.

  20. Sealing performance of a magnetic fluid seal for rotary blood pumps.

    PubMed

    Mitamura, Yoshinori; Takahashi, Sayaka; Kano, Kentaro; Okamoto, Eiji; Murabayashi, Shun; Nishimura, Ikuya; Higuchi, Taka-Aki

    2009-09-01

    A magnetic fluid (MF) for a rotary blood pump seal enables mechanical contact-free rotation of the shaft and, hence, has excellent durability. The performance of a MF seal, however, has been reported to decrease in liquids. We have developed a MF seal that has a "shield" mechanism and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Under the condition of continuous flow, the MF seal remained in perfect condition against a pressure of 298 mm Hg (pump flow rate: 3.96 L/min). The seal was also perfect against a pressure of 170 mm Hg in a continuous flow of 3.9 L/min for 275 days. We have developed a MF seal that works in liquid against clinically used pressures. The MF seal is promising as a shaft seal for rotary blood pumps.

  1. Classification of Implantable Rotary Blood Pump States With Class Noise.

    PubMed

    Ooi, Hui-Lee; Seera, Manjeevan; Ng, Siew-Cheok; Lim, Chee Peng; Loo, Chu Kiong; Lovell, Nigel H; Redmond, Stephen J; Lim, Einly

    2016-05-01

    A medical case study related to implantable rotary blood pumps is examined. Five classifiers and two ensemble classifiers are applied to process the signals collected from the pumps for the identification of the aortic valve nonopening pump state. In addition to the noise-free datasets, up to 40% class noise has been added to the signals to evaluate the classification performance when mislabeling is present in the classifier training set. In order to ensure a reliable diagnostic model for the identification of the pump states, classifications performed with and without class noise are evaluated. The multilayer perceptron emerged as the best performing classifier for pump state detection due to its high accuracy as well as robustness against class noise.

  2. Development of an implantable motor-driven assist pump system.

    PubMed

    Mitamura, Y; Okamoto, E; Hirano, A; Mikami, T

    1990-02-01

    A motor-driven artificial pump and its transcutaneous energy transmission (TET) system have been developed. The artificial pump consists of a high-speed dc brushless motor driving a ball screw and magnetic coupling mechanism between the blood pump and ball screw. The ball screw transfers high-speed rotary motion into low-speed rectilinear motion by a single component. Magnetic coupling enables active blood filling without applying an excess negative pressure to the pump. The transcutaneous transformer is formed from a pair of concave/convex ferrite cores. This design minimizes lateral motion of the external core. Information on motor voltage is transmitted through the skin by infrared pulses. The motor voltage is regulated by controlling the duty ratio of the square pulse supplied to the primary coil. Pump flow of 5.6 l/min was obtained with a mean outlet pressure of 100 mmHg at a drive rate of 100 bpm under preload of 15 mmHg. The performance of synchronous pumping has been very satisfactory. Continuous pumping was maintained by the backup battery in the case of interruption of TET. 24 W were transmitted by TET system with 78 percent of efficiency. Temperature rise of the internal core was 0.2 C. The developed system is promising as an implantable assist pump system.

  3. Preliminary validation of a new magnetic wireless blood pump.

    PubMed

    Kim, Sung Hoon; Ishiyama, Kazushi; Hashi, Shuichiro; Shiraishi, Yasuyuki; Hayatsu, Yukihiro; Akiyama, Masatoshi; Saiki, Yoshikatsu; Yambe, Tomoyuki

    2013-10-01

    In general, a blood pump must be small, have a simple configuration, and have sufficient hydrodynamic performance. Herein, we introduce new mechanisms for a wireless blood pump that is small and simple and provides wireless and battery-free operation. To achieve wireless and battery-free operation, we implement magnetic torque and force control methods that use two external drivers: an external coil and a permanent magnet with a DC-motor, respectively. Power harvesting can be used to drive an electronic circuit for wireless monitoring (the observation of the pump conditions and temperature) without the use of an internal battery. The power harvesting will be used as a power source to drive other electronic devices, such as various biosensors with their driving circuits. To have both a compact size and sufficient pumping capability, the fully magnetic impeller has five stages and each stage includes four backward-curved blades. The pump has total and inner volumes of 20 and 9.8 cc, respectively, and weighs 52 g. The pump produces a flow rate of approximately 8 L/min at 80 mm Hg and the power generator produces 0.3 W of electrical power at 120 Ω. The pump also produces a minimum flow rate of 1.5 L/min and a pressure of 30 mm Hg for circulation at a maximum distance of 7.5 cm.

  4. Hydraulic refinement of an intraarterial microaxial blood pump.

    PubMed

    Siess, T; Reul, H; Rau, G

    1995-05-01

    Intravascularly operating microaxial pumps have been introduced clinically proving to be useful tools for cardiac assist. However, a number of complications have been reported in literature associated with the extra-corporeal motor and the flexible drive shaft cable. In this paper, a new pump concept is presented which has been mechanically and hydraulically refined during the developing process. The drive shaft cable has been replaced by a proximally integrated micro electric motor and an extra-corporeal power supply. The conduit between pump and power supply consists of only an electrical power cable within the catheter resulting in a device which is indifferent to kinking and small curvature radii. Anticipated insertion difficulties, as a result of a large outer pump diameter, led to a two-step approach with an initial 6,4mm pump version and a secondary 5,4mm version. Both pumps meet the hydraulic requirement of at least 2.5l/min at a differential pressure of 80-100 mmHg. The hydraulic refinements necessary to achieve the anticipated goal are based on ongoing hydrodynamic studies of the flow inside the pumps. Flow visualization on a 10:1 scale model as well as on 1:1 scale pumps have yielded significant improvements in the overall hydraulic performance of the pumps. One example of this iterative developing process by means of geometrical changes on the basis of flow visualization is illustrated for the 6.4mm pump.

  5. Experimental determination of dynamic characteristics of the VentrAssist implantable rotary blood pump.

    PubMed

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Qian, Yi

    2004-12-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump consists of a shaftless impeller, which also acts as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, which result from the small clearances between the outside surfaces of the impeller and the pump cavity. These small clearances range from approximately 50 microm to 230 microm in size in the version of pump reported here. This article presents experimental investigation into the dynamic characteristics of the impeller-bearing-pump housing system of the rotary blood pump for increasing pump speeds at different flow rates. The pump was mounted on a suspension system consisting of a platform and springs, where the natural frequency and damping ratio for the suspension system were determined. Real-time measurements of the impeller's displacement were performed using Hall effect sensors. A vertical disturbance force was exerted onto the pump housing, causing the impeller to be displaced in vertical direction from its dynamic equilibrium position within the pump cavity. The impeller displacement was represented by a decaying sine wave, which indicated the impeller restoring to its equilibrium position. From the decaying sine wave the natural frequency and stiffness coefficient of the system were determined. Furthermore, the logarithmic decrement method was used to determine the damping ratio and eventually the damping coefficient of the system. Results indicate that stiffness and damping coefficients increased as flow rate and pump speed increased, representing an increase in stability with these changing conditions. However, pump speed had a greater influence on the stiffness and damping coefficients than flow rate did, which was evident through dynamic analysis. Overall the experimental method presented in this

  6. Centrifugal blood pump with a hydraulically-levitated impeller for a permanently implantable biventricular assist device.

    PubMed

    Watanabe, Kuniyoshi; Ichikawa, Seiji; Asai, Toshimasa; Motomura, Tadashi; Hata, Atsushi; Ito, Seiichi; Shinohara, Toshiyuki; Tsujimura, Shinichi; Glueck, Julia A; Oestmann, Daniel J; Nosé, Yukihiko

    2004-06-01

    A permanently implantable biventricular assist device (BVAD) system has been developed with a centrifugal pump which is activated by a hydraulically-levitated impeller. The pump impeller floats hydraulically into the top contact position; this position prevents thrombus formation by creating a washout effect at the bottom bearing area, a common stagnant region. The pump was subjected to in vitro studies using a pulsatile mock circulation loop to confirm the impeller's top contact position and the swinging motion produced by the pulsation. Eleven in vivo BVAD studies confirmed that this swinging motion eliminated blood clot formation. Twenty-one pumps im-planted for up to three months did not reveal any thrombosis in the pumps or downstream organs. One exception was a right pump which was exposed to severe low flow due to the kinking of the outflow graft by the accidental pulling of the flow meter cable. Three ninety-day BVAD studies were achieved without thrombus formation.

  7. A miniature intraventricular axial flow blood pump that is introduced through the left ventricular apex.

    PubMed

    Yamazaki, K; Umezu, M; Koyanagi, H; Kitamura, M; Eishi, K; Kawai, A; Tagusari, O; Niinami, H; Akimoto, T; Nojiri, C

    1992-01-01

    A new intraventricular axial flow blood pump has been designed and developed as an implantable left ventricular assist device (LVAD). The pump consists of a tube housing (10 cm in length and 14 mm in diameter), a three-vane impeller combined with a guide vane, and a DC motor. This pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged into the ascending aorta. A pump flow of > 8 L/min was obtained against 90 mmHg differential pressure in the mock circulatory system. In an acute dog model, this pump could produce a sufficient output of 200 ml/kg/min. In addition, the pump flow profile demonstrated a pulsatile pattern, although the rotation speed was fixed. This is mainly due to the changes in flow rate during a cardiac cycle--that is, during systole, the flow rate increases to the maximum, while the differential pressure between the LV and the aorta decreases to the minimum. Thus, this simple and compact axial flow blood pump can be a potential LVAD, with prompt accessibility and need for less invasive surgical procedures.

  8. Water Pump Development for the EVA PLSS

    NASA Technical Reports Server (NTRS)

    Schuller, Michael; Kurwitz, Cable; Goldman, Jeff; Morris, Kim; Trevino, Luis

    2009-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design, fabricate, and test a preflight prototype pump for use in the Extravehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump will accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting noncondensable gas without becoming "air locked." The chosen pump design consists of a 28 V DC, brushless, sealless, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. Although the planned flight unit will use a sensorless motor with custom designed controller, the preflight prototype to be provided for this project incorporates Hall effect sensors, allowing an interface with a readily available commercial motor controller. This design approach reduced the cost of this project and gives NASA more flexibility in future PLSS laboratory testing. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES will simulate the vacuum environment in which the flight pump will operate. Testing will verify that the pump meets design requirements for range of flow rates, pressure rise, power consumption, working fluid temperature, operating time, and restart capability. Pump testing is currently

  9. The status of failure and reliability testing of artificial blood pumps.

    PubMed

    Patel, Sonna M; Throckmorton, Amy L; Untaroiu, Alexandrina; Allaire, Paul E; Wood, Houston G; Olsen, Don B

    2005-01-01

    Artificial blood pumps are today's most promising bridge-to-transplant, bridge-to-recovery, and destination therapy solutions for patients with congestive heart failure. There is a critical need for increased reliability and safety as the next generation of artificial blood pumps approach final development for long-term destination therapy. To date, extensive failure and reliability studies of these devices are considered intellectual property and thus remain unpublished. Presently, the Novacor N100PC, Thoratec VAD, and HeartMate LVAS (IP and XVE) comprise the only four artificial blood pumps commercially available for the treatment of congestive heart failure in the United States. The CardioWest TAH recently received premarket approval from the US Food and Drug Administration. With investigational device exemptions, the AB-180, AbioCor, LionHeart, DeBakey, and Flowmaker are approved for clinical testing. Other blood pumps, such as the American BioMed-Baylor TAH, CorAide, Cleveland Clinic-Nimbus TAH, HeartMate III, Hemadyne, and MagScrew TAH are currently in various stages of mock loop and animal testing, as indicated in published literature. This article extensively reviews in vitro testing, in vivo testing, and the early clinical testing of artificial blood pumps in the United States, as it relates to failure and reliability. This detailed literature review has not been published before and provides a thorough documentation of available data and testing procedures regarding failure and reliability of these various pumps.

  10. An implantable centrifugal blood pump with a recirculating purge system (Cool-Seal system).

    PubMed

    Yamazaki, K; Litwak, P; Tagusari, O; Mori, T; Kono, K; Kameneva, M; Watach, M; Gordon, L; Miyagishima, M; Tomioka, J; Umezu, M; Outa, E; Antaki, J F; Kormos, R L; Koyanagi, H; Griffith, B P

    1998-06-01

    A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 x 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool-Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5-9 L/min, and pump power consumption remained stable at 9-10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).

  11. Simple in vitro testing method for antithrombogenic evaluation of centrifugal blood pumps.

    PubMed

    Maruyama, Osamu; Tomari, Yosuke; Sugiyama, Daisuke; Nishida, Masahiro; Tsutsui, Tatsuo; Yamane, Takashi

    2009-01-01

    We developed a simple in vitro antithrombogenic testing method using a mock circulation system as used in the hemolysis tests to evaluate the antithrombogenicity of centrifugal blood pumps. This method was not designed to substitute for animal experiments but was intended to be a screening test method for selecting pumps robust enough to operate properly during animal experiments. In this study, we were able to maintain an almost constant activated clotting time for test blood for 10 hours by using both trisodium citrate and calcium chloride. We carried out the in vitro antithrombogenic testing of monopivot type centrifugal blood pumps (models DD3 and DD6) and hydrodynamic bearing pumps (models HH2 and HH7), which were developed at Advanced Industrial Science and Technology. Thrombus formation was not observed in the DD3 or DD6 pumps but occurred in the HH2 and HH7 pumps. The HH2 pump generated thrombi during a 1.5-hour ex vivo test, and the test was terminated. We expect this in vitro testing method to be useful for undertaking evaluations before animal experiments.

  12. New investigations of a pulsatile impeller blood pump.

    PubMed

    Qian, K X

    1990-01-01

    For circulatory assist devices and total artificial heart systems, impeller blood pumps with small total volumes would be fully implantable. One of the main obstacles, however, is generation of a pulsatile flow. The simplest way to overcome this problem is by changing the pump's revolutions per minute (rpm) periodically, but this often results in severe hemolysis. After theoretic analysis, two in vitro models of impeller blood pumps have been devised, producing pulsatile flow with constant rpm. In the first model, the impeller oscillates in an axial direction during constant rotation. The pump is driven by a DC motor (rotating) and a pneumatic device (oscillating). The form of the pulsatile pressure wave depends upon duration and amplitude of the oscillation. With 40% systolic duration and a 50 mm axial amplitude, a 70 mmHg pressure amplitude (170/100) is achieved with a semiphysiologic shape at a flow of 12 L/min. The second model produces a pulsatile flow by differing the gaps between impeller and cap on the inlet pipe. Both the cap and impeller have cone-shaped heads, and impeller oscillations of 1.5-2 mm, for example, results in a pressure pulse of 40 mmHg (150-110) at 7 L/min flow. Results of theoretic analyses have shown that both models create less turbulence in the impeller, with a consequent reduction in blood cell damage as compared to pumps with changing rpms.

  13. A travelling wave dielectrophoretic pump for blood delivery.

    PubMed

    Lei, U; Huang, C W; Chen, James; Yang, C Y; Lo, Y J; Wo, Andrew; Chen, C F; Fung, T W

    2009-05-21

    The travelling wave dielectrophoretic pump studied here is essentially a rectangular straight micro-channel with an electrode array on part of its wall, and operated under an ac voltage with phase shift at neighbouring electrodes. The travelling wave dielectrophoretic force drives the cells, which drag the plasma, and after some sophisticated interaction between conventional dielectrophoresis, travelling wave dielectrophoresis and fluid mechanics, the whole blood is delivered. The pump was fabricated using MEMS techniques and studied in details for different parameters. It is found that the pumping velocity is maximized at an intermediate frequency around 20-30 MHz (varies with phase shift), and at an intermediate channel height at about 40 microm. The quasi-static average cell velocity can reach 15 microm s(-1) for a pump with 1 mm length and 16 electrodes (total array length 465 microm) operated at 5 V and 20 MHz with 90 degrees phase shift.

  14. Performance of enlarged blood pump models with five different impellers.

    PubMed

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In earlier studies, a 5:1 enlarged pump model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump had been constructed and the flow characteristics investigated. Although the results obtained were satisfactory, the medium used was air. A 5:1 enlarged pump model using water as the medium thus was designed and constructed. Five different impeller blade profile designs were used in the present study. By varying (1) the blade profile design: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed, the flow characteristics of the pump were investigated. It was found that the impeller with the higher number of blades, used in the forward and straight blade profiles, have the best performance.

  15. Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass.

    PubMed

    Orime, Y; Shiono, M; Yagi, S; Yamamoto, T; Okumura, H; Nakata, K; Kimura, S; Hata, M; Sezai, A; Kashiwazaki, S; Choh, S; Negishi, N; Sezai, Y; Matsui, T; Suzuki, M

    2000-06-01

    The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.

  16. Experimental and Numerical Investigation of an Axial Rotary Blood Pump.

    PubMed

    Schüle, Chan Yong; Thamsen, Bente; Blümel, Bastian; Lommel, Michael; Karakaya, Tamer; Paschereit, Christian Oliver; Affeld, Klaus; Kertzscher, Ulrich

    2016-11-01

    Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near-wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds-averaged Navier-Stokes simulations-computational fluid dynamics (URANS-CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall-particle image velocimetry technique, and the visualization of near-wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS-CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal

  17. Development and initial testing of a permanently implantable centrifugal pump.

    PubMed

    Nakazawa, T; Takami, Y; Benkowski, R; Ohtsubo, S; Yukio, O; Tayama, E; Ohtsuka, G; Niimi, Y; Glueck, J; Sueoka, A; Schmallegger, H; Schima, H; Wolner, E; Nosé, Y

    1997-07-01

    To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 L/min against 150 mm Hg at 2,500 rpm. The normalized index of hemolysis (NIH) value of this pump was 0.0028 g/100 L at 5 L/min against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device.

  18. Magnetically suspended centrifugal blood pump with a radial magnetic driver.

    PubMed

    Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

    2005-01-01

    A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps.

  19. A new rotary blood pump for versatile extracorporeal circulation: the DeltaStream.

    PubMed

    Göbel, C; Arvand, A; Rau, G; Reul, H; Meyns, B; Flameng, W; Eilers, R; Marseille, O

    2002-09-01

    Today, rotary pumps are routinely used for extracorporeal circulation in different clinical settings and applications. A review of these applications and specific limitations in extracorporeal perfusion was performed and served as a basis for the development of the DeltaStream. The DeltaStreams is a miniaturized rotary blood pump of a new and unique design with an integrated drive unit. Despite its small design, the pump maintains a sufficient hydraulic capacity, which makes the DeltaStream very flexible for intra- and perioperative applications. It also opens the field for short-term ventricular assist devices (VAD) applications or use as a component in extracorporeal life support systems (ECLS). The DeltaStream and, specifically, its impeller design have been optimized with respect to haemolysis and nonthrombogenicity. Also, the pump facilitates an effective pulse generation in VAD applications and simulates heart action in a more physiological way than other rotary pumps or roller pumps. Hydraulic and haematological properties have been tested in vitro and in vivo. In a series of seven animal experiments in two different setups, the pump demonstrated its biocompatibility and applicability. Basic aspects of the DeltaStream pump concept as well as important console features are presented. A summary of the final investigation of this pump is given with focus on hydraulic capabilities and results from animal studies.

  20. Axial type self-bearing motor for axial flow blood pump.

    PubMed

    Okada, Yohji; Masuzawa, Toru; Matsuda, Ken-Ichi; Ohmori, Kunihiro; Yamane, Takashi; Konishi, Yoshiaki; Fukahori, Shinya; Ueno, Satoshi; Kim, Seung-Jong

    2003-10-01

    An axial self-bearing motor is proposed which can drive an axial blood pump without physical contact. It is a functional combination of the bi-directional disc motor and the axial active magnetic bearing, where it actively controls single degree-of-freedom motion, while other motions such as lateral vibration are passively stable. For application to a blood pump, the proposed self-bearing motor has the advantages of simple structure and small size. Through the finite element method (FEM) analysis and the experimental test, its good feasibility is verified. Finally, the axial flow pump is fabricated using the developed magnetically suspended motor. The pump test is carried out and the results are discussed in detail.

  1. The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery.

    PubMed

    Datt, Bharat; Nguyen, Moui B; Plancher, Gary; Ruzmetov, Mark; O'Brien, Michael; Kube, Alicia; Munro, Hamish M; Pourmoghadam, Kamal K; DeCampli, William M

    2017-03-01

    Centrifugal pumps are considered to be less destructive to blood elements (1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients <13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group, n = 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group, n = 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p < .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p < .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining higher

  2. The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery

    PubMed Central

    Datt, Bharat; Nguyen, Moui B.; Plancher, Gary; Ruzmetov, Mark; O'Brien, Michael; Kube, Alicia; Munro, Hamish M.; Pourmoghadam, Kamal K.; DeCampli, William M.

    2017-01-01

    Abstract: Centrifugal pumps are considered to be less destructive to blood elements (1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients <13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group, n = 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group, n = 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p < .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p < .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining

  3. Microfabricated electrolysis pump system for isolating rare cells in blood

    NASA Astrophysics Data System (ADS)

    Furdui, Vasile I.; Kariuki, James K.; Jed Harrison, D.

    2003-07-01

    An integrated system for immunomagnetic separation of rare cells from blood is presented. A micromachined device was fabricated by bonding silicon die with etched structures to a glass cover plate on which electrodes are defined. Electrolytic generation of gas from 0.50 M KNO3 (aqueous) provided pumping actuation for a device that performed the capture and purification of rare cells spiked into a 7.5 µl reconstituted blood sample. The system consisted of two pumps, a sample and a wash buffer meander reservoir, and a main channel for magnetic field trapping of rare cells captured by antibody-coated magnetic beads. A maximum pumping rate of 1.4 +/- 0.1 µl min-1 was obtained at a current of 180 µA, and the maximum blood sample volume delivered to the capture bed was 6.5-7 µl. The trapped cells could be washed with the buffer from the second pump and then delivered to the exit port of the chip after removing the magnetic field.

  4. Computer modeling of interactions of an electric motor, circulatory system, and rotary blood pump.

    PubMed

    Xu, L; Fu, M

    2000-01-01

    The innovative ventricular assist systems (IVAS) is the next generation ventricular assist device for use as a permanent implantable device. Its practical application depends upon control of the electric motor and interactions of the electric motor, blood pump, and circulatory system. Computer modeling and simulation are necessary to investigate and evaluate the interactions and feasibility of sophisticated control algorithms. In this paper, a computer model of the complete system, including the cardiovascular system, blood pump, and electric motor, is proposed. The model is obtained based on an electric circuit model of the cardiovascular system, a parametric model of the blood pump, and a dynamic model of the electric motor. The cardiovascular system uses nonlinear parameters to simulate the time-varying property of the ventricles, and the cannula collapse effect caused by over-pumping. The blood pump model can be obtained either from pump design data, or test data. The motor control can be operated with closed-loop regulation, depending upon physiologic requirements. Different operation modes (current or speed) of the electric motor can be simulated. The computer model is implemented using MATLAB. Various motor operation modes are simulated and their effects are evaluated. By adjusting the motor input, the pump can achieve proper output so that normal physiology can be obtained. In addition to evaluating existing operation modes and their effect on the physiologic system, the computer simulation results show that this computer model can contribute significantly to the development of new physiologic control algorithms. It is demonstrated that, using this motor-pump-physiology interaction model, development of an innovative ventricular assist system can be greatly facilitated.

  5. Impact of hyperthermal rotary blood pump surfaces on blood clotting behavior: an approach.

    PubMed

    Hamilton, Kathrin F; Schlanstein, Peter C; Mager, Ilona; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2009-09-01

    The influence of heat dissipating systems, such as rotary blood pumps, was investigated. Titanium cylinders as rotary blood pump housing dummies were immersed in porcine blood and constantly tempered at specific temperatures (37-60 degrees C) over a defined period of time. The porcine blood was anticoagulated either by low heparin dosage or citrate. At frequent intervals, samples were taken for blood analysis and the determination of the plasmatic coagulation cascade. Blood parameters do not alter at surface temperatures below 50 degrees C. Hyperthermia-induced hemolysis could be confirmed. The plasmatic coagulation cascade is terminated at surface temperatures exceeding 55 degrees C. The adhesion of blood constituents on surfaces is temperature and time dependent, and structural changes of adhesions and blood itself were detected.

  6. A new design and computational fluid dynamics study of an implantable axial blood pump.

    PubMed

    Koochaki, Mojtaba; Niroomand-Oscuii, Hanieh

    2013-12-01

    Considering small thoracic space, using implantable ventricular assist device requires reduction in a pump size. Among many available blood pumps, axial blood pumps have attracted greatly because of their small size. In this article, a new miniature axial blood pump has been designed and studied which can be easily implanted in the human body. In this design, the pump overall length decreased by a little increasing in the pump diameter, and new blade geometry is used to produce a streamlined, idealized, and nonobstructing blood flow path in the pump. By means of computational fluid dynamic, the flow pattern through the pump has been predicted and overall pump performance and efficiency has been computed. Also, to ensure a reliable VAD design, two methods for checking wall shear stress were used to confirm that this pump wouldn't cause serious blood damage.

  7. Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near-infrared light.

    PubMed

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

    2014-09-01

    Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near-infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750 nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200 s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750 nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780 rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump.

  8. Survey of blood pump diaphragm damage in the NIPRO-ventricular assist device.

    PubMed

    Kashiwa, Koichi; Nishimura, Takashi; Nakahata, Aoi; Momose, Naoki; Umeda, Chinori; Kubo, Hitoshi; Tamai, Hisayoshi; Kinugawa, Koichiro; Adachi, Hideo; Yamaguchi, Atsushi; Yambe, Tomoyuki; Katohgi, Toshiyuki; Kyo, Shunei; Ono, Minoru

    2012-12-01

    We surveyed the incidence of blood pump diaphragm damage (rupture or crack) in the NIPRO-ventricular assist device (VAD). In the cases in which rupture or suspected blood pump crack was detected, we disassembled the pumps to visually check the condition of the diaphragm after replacement or use. Of 366 blood pumps surveyed, diaphragm damage was observed in 2.7 %. The duration of use of the blood pumps with diaphragm damage was significantly longer than that of pumps without damage. The incidence of diaphragm damage increased with longer duration of use. On the basis of these findings, blood pump diaphragm damage in the NIPRO-VAD may be associated with duration of use. However, some blood pumps were used for prolonged periods without diaphragm damage. All blood pumps with damage had a crack in the diaphragm on the air chamber side near the diaphragm-housing (D-H) junction. Cracks were not found in any specific part of the diaphragm. In blood pumps with diaphragm rupture, the crack had a through-hole reaching the blood-contacting surface. Although we were unable to identify the causes of the cracks, it is suggested that when a crack appears in the diaphragm it will gradually expand and eventually lead to rupture. If a crack is detected in a blood pump, we advocate replacing the pump before it grows. When the NIPRO-VAD is used, it is necessary to keep in mind that blood pump diaphragm damage may occur.

  9. Coal pump development phase 3

    NASA Technical Reports Server (NTRS)

    Kushida, R. O.; Sankur, V. D.; Gerbracht, F. G.; Mahajan, V.

    1980-01-01

    Techniques for achieving continuous coal sprays were studied. Coazial injection with gas and pressure atomization were studied. Coal particles, upon cooling, were found to be porous and fragile. Reactivity tests on the extruded coal showed overall conversion to gases and liquids unchanged from that of the raw coal. The potentials for applications of the coal pump to eight coal conversion processes were examined.

  10. Long-term animal experiments with an intraventricular axial flow blood pump.

    PubMed

    Yamazaki, K; Kormos, R L; Litwak, P; Tagusari, O; Mori, T; Antaki, J F; Kameneva, M; Watach, M; Gordon, L; Mukuo, H; Umezu, M; Tomioka, J; Outa, E; Griffith, B P; Koyanagai, H

    1997-01-01

    A miniature intraventricular axial flow blood pump (IVAP) is undergoing in vivo evaluation in calves. The IVAP system consists of a miniature (phi 13.9 mm) axial flow pump that resides within the left ventricular (LV) chamber and a brushless DC motor. The pump is fabricated from titanium alloy, and the pump weight is 170 g. It produces a flow rate of over 5 L/min against 100 mmHg pressure at 9,000 rpm with an 8 W total power consumption. The maximum total efficiency exceeds 17%. A purged lip seal system is used in prototype no. 8, and a newly developed "Cool-Seal" (a low temperature mechanical seal) is used in prototype no. 9. In the Cool-Seal system, a large amount of purge flow is introduced behind the seal faces to augment convective heat transfer, keeping the seal face temperature at a low level for prevention of heat denaturation of blood proteins. The Cool-Seal system consumes < 10 cc purge fluid per day and has greatly extended seal life. The pumps were implanted in three calves (26, 30, and 168 days of support). The pump was inserted through a left thoracotomy at the fifth intercostal space. Two pursestring sutures were placed on the LV apex, and the apex was cored with a myocardial punch. The pump was inserted into the LV with the outlet cannula smoothly passing through the aortic valve without any difficulty. Only 5 min elapsed between the time of chest opening and initiation of pumping. Pump function remained stable throughout in all experiments. No cardiac arrhythmias were detected, even at treadmill exercise tests. The plasma free hemoglobin level remained in the acceptable range. Post mortem examination did not reveal any interference between the pump and the mitral apparatus. No major thromboembolism was detected in the vital organs in Cases 1 or 2, but a few small renal infarcts were detected in Case 3.

  11. Impeller behavior and displacement of the VentrAssist implantable rotary blood pump.

    PubMed

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Woodard, John C

    2004-03-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 microm to 230 microm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy-current proximity sensors and laser proximity sensors. The second experiment used Hall-effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, theta(x), and theta(y)). The sixth degree of freedom, the rotation about the impeller axis (theta(z)), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 micro m to 222 microm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing.

  12. Classification of physiologically significant pumping states in an implantable rotary blood pump: effects of cardiac rhythm disturbances.

    PubMed

    Karantonis, Dean M; Lovell, Nigel H; Ayre, Peter J; Mason, David G; Cloherty, Shaun L

    2007-06-01

    Methods of speed control for implantable rotary blood pumps (iRBPs) are vital for providing implant recipients with sufficient blood flow to cater for their physiological requirements. The detection of pumping states that reflect the physiological state of the native heart forms a major component of such a control method. Employing data from a number of acute animal experiments, five such pumping states have been previously identified: regurgitant pump flow, ventricular ejection (VE), nonopening of the aortic valve (ANO), and partial collapse (intermittent [PVC-I] and continuous [PVC-C]) of the ventricle wall. An automated approach that noninvasively detects such pumping states, employing a classification and regression tree (CART), has also been developed. An extension to this technique, involving an investigation into the effects of cardiac rhythm disturbances on the state detection process, is discussed. When incorporating animal data containing arrhythmic events into the CART model, the strategy showed a marked improvement in detecting pumping states as compared to the model devoid of arrhythmic data: state VE--57.4/91.7% (sensitivity/specificity) improved to 97.1/100.0%; state PVC-I--66.7/83.1% improved to 100.0/88.3%, and state PVC-C--11.1/66.2% changed to 0.0/100%. With a simplified binary scheme differentiating suction (PVC-I, PVC-C) and nonsuction (VE, ANO) states, suction was initially detected with 100/98.5% sensitivity/specificity, whereas with the subsequent improved model, both these states were detected with 100% sensitivity. The accuracy achieved demonstrates the robustness of the technique presented, and substantiates its inclusion into any iRBP control methodology.

  13. Magnetically suspended rotary blood pump with radial type combined motor-bearing.

    PubMed

    Masuzawa, T; Kita, T; Matsuda, K; Okada, Y

    2000-06-01

    A magnetically suspended centrifugal blood pump is being developed with a combined motor-bearing for long-term ventricular assist systems. The combined motor-bearing actively suspends a rotor in a radial direction to deal with radial force unbalance in the pump and rotates the rotor by using the electric magnetic field. Therefore, the pump has no mechanical parts such as bearings of the motor and has a long lifetime. The developed pump consists of a thin rotor with a semi open-type 6 vane impeller and a stator to suspend and rotate the rotor. The rotor has 4-pole permanent magnets on the circumferential surface. The outer diameter and the thickness of the rotor are 60 mm and 8 mm, respectively. Axial movement and tilt of the rotor are restricted by passive stability based on the thin rotor structure. Radial movements of the rotor, such as levitation in radial direction and rotation, are controlled actively by using electric magnets of the stator. The electric magnet coils to produce levitation and rotation forces are constructed on the periphery stator. The p +/- 2-pole algorithm and the synchronous motor mechanism are adopted to levitate and rotate the rotor. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was connected to the developed pump to examine the basic performance of the pump and the magnetic suspension system. Maximum rotational speed, flow rate, and head were 2,800 rpm, 11 L/min, and 270 mm Hg, respectively. The rotor with the impeller could be suspended completely during the entire pumping process. We conclude the pump with the combined motor-bearing has sufficient performance for the blood pump.

  14. Magnetically suspended centrifugal blood pump with an axially levitated motor.

    PubMed

    Masuzawa, Toru; Ezoe, Shiroh; Kato, Tsuyoshi; Okada, Yohji

    2003-07-01

    The longevity of a rotary blood pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal blood pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The pump shows promise as a ventricular assist device.

  15. Development of the sonic pump levitation

    NASA Technical Reports Server (NTRS)

    Dunn, S. A.

    1984-01-01

    A prototype levitating/positioning device termed the Sonic Pump Levitator was designed, built and successfully tested in full gravity and in the reduced gravity of the parabolic flight regime of the KC-135. Positioning is achieved by timely and appropriate application of gas momentum from one or more of six sonic pumps. The sonic pumps, which are arranged orthogonally in opposed pairs about the levitation region, are activated by an electro-optical, computer controlled, feedback system. The sonic pump is a transducer which is capable of converting sound energy into a directed flow of gas. It consists of a loudspeaker whose face is sealed by a closure perforated by one or more orifices. The diaphragm of the loudspeaker is the only moving part of the sonic pump, no valves being needed. This very low inertia electromechanical device was developed to provide the short response time necessary to keep pace with the demands of computerized position keeping.

  16. Numerical Calculation for Whirling Motion of a Centrifugal Blood Pump with Conical Spiral Groove Bearings

    NASA Astrophysics Data System (ADS)

    Shigemaru, Daichi; Tsukamoto, Hiroshi

    2010-06-01

    Whirling motion of a pump impeller was calculated for the centrifugal blood pump with Conical Spiral Groove Bearings to get a criterion for the instability of impeller whirling motion. The motion of the centrifugal blood pump impeller was calculated based on a spring damping model, and unsteady flow in the pump was computed using the commercial CFD package ANSYS CFX. Also the whirling motion of rotating impeller was measured using two displacement sensors fixed to the blood pump casing. The numerical calculations were done for the blood pump impeller with conical spiral groove bearings, and impeller whirling motion was evaluated.

  17. Solar powered circulation pump development

    NASA Astrophysics Data System (ADS)

    Johnson, A. L.

    1980-09-01

    The state-of-the-art of liquid piston heat engines was examined. Next, a morphological analysis of the original concept was performed. An analysis of the pump performance from a theoretical basis was performed by deriving and solving the equations governing the cycle. The results are documented. An experimental evaluation of the condensing phenomena was performed. It was assumed that the boiling could be conducted in the solar panel. A number of solar panel designs were examined, and the most appropriate type of solar panel is described. A 1/4th scale unit was fabricated and tested. The overall efficiency was approximately 1% at the design point, compared with a theoretical limit of 1.6% for the given operating conditions. The production costs of the full size pump were examined. Systems integration aspects were considered and the results are presented.

  18. Design of axial blood pumps for patients with dysfunctional fontan physiology: computational studies and performance testing.

    PubMed

    Kafagy, Dhyaa H; Dwyer, Thomas W; McKenna, Kelli L; Mulles, Jean P; Chopski, Steven G; Moskowitz, William B; Throckmorton, Amy L

    2015-01-01

    Limited treatment options for patients having dysfunctional single ventricle physiology motivate the necessity for alternative therapeutic options. To address this unmet need, we are developing a collapsible axial flow blood pump. This study investigated the impact of geometric simplicity to facilitate percutaneous placement and maintain optimal performance. Three new pump designs were numerically evaluated. A transient simulation explored the impact of respiration on blood flow conditions over the entire respiratory cycle. Prototype testing of the top performing pump design was completed. The top performing Rec design generated the highest pressure rise range of 2-38 mm Hg for flow rates of 1-4 L/min at 4000-7000 RPM, exceeding the performance of the other two configurations by more than 26%. The blood damage indices for the new pump designs were determined to be below 0.5% and predicted hemolysis levels remained low at less than 7 × 10(-5)  g/100 L. Prototype testing of the Rec design confirmed numerical predictions to within an average of approximately 22%. These findings demonstrate that the pumps are reasonably versatile in operational ability, meet pressure-flow requirements to support Fontan patients, and are expected to have low levels of blood trauma.

  19. Completely pulsatile high flow circulatory support with a constant-speed centrifugal blood pump: mechanisms and early clinical observations.

    PubMed

    Yamazaki, Kenji; Saito, Satoshi; Kihara, Shinichiro; Tagusari, Osamu; Kurosawa, Hiromi

    2007-04-01

    Various types of rotary blood pumps (axial flow, centrifugal) have been introduced into clinical use recently. These pumps have different pressure-flow characteristics, and some investigators have noted that a limited pump flow rate and less pulsatility are the problems with the axial flow devices. A new implantable centrifugal blood pump was developed that has an extremely flat pressure-flow curve and is able to produce a significantly high pump flow rate of 20 l/min at a low pressure of 10-30mmHg. When the pressure difference between the left ventricle and aorta decreases during systole, an instant high peak flow is achieved, which results in a higher peak pressure in the aorta (systolic pressure). During the diastolic phase, the left ventricle-aorta pressure difference increases to maximum, and the pump flow rate decreases to minimum. Thus, the pump flow rate becomes completely pulsatile, and the high peak flow provides a higher mean pump flow rate. This pump was applied to two end-stage heart failure patients (dilated cardiomyopathy, New York Heart Association (NYHA) class IV, inotrope-dependent). The pump was observed to provide completely pulsatile high flow assistance of 6-9 l/min with a constant pump speed. Both patients are currently in NYHA class I after 1 year on the device with no major adverse events. The new centrifugal blood pump provides completely pulsatile high-flow circulatory support with a constant pump speed, which solves the current clinical problems with rotary blood pumps.

  20. Advanced heat pump research and development

    NASA Astrophysics Data System (ADS)

    Kuliasha, M. A.

    The Office of Building Energy Research and Development of the U.S. Department of Energy (DOE), has been funding R&D in advanced heat pumps and appliances since 1976. Much of that research has been managed for DOE by the Oak Ridge National Laboratory (ORNL). The objective of the Building Equipment Research (BER) program at ORNL has been to generate new concepts and develop a technology base for improving the energy efficiency and load characteristics of energy conversion equipment used in residential and commercial buildings. The research being pursued to achieve these objectives falls under three general areas: thermally activated heat pumps (TAHP), refrigeration systems, and building equipment systems. The TAHP work is concentrated on three technologies: (1) absorption heat pumps; (2) Stirling engine-driven heat pumps; and (3) internal combustion (IC) engine-driven heat pumps. Major project areas in refrigeration systems research include electric heat pumps, ground-coupled heat pumps, and refigerant mixtures. In the building equipment systems areas, project areas include advanced distribution systems, advanced insulation for appliances, and commercial building equipment.

  1. Circular pump support of blood circulation in the human body

    NASA Astrophysics Data System (ADS)

    Medvedev, A. E.; Fomin, V. M.; Prikhodko, Yu. M.; Cherniavskiy, A. M.; Fomichev, V. P.; Fomichev, A. V.; Chekhov, V. P.; Ruzmatov, T. M.

    2016-10-01

    The need of circulatory support systems in the treatment of chronic heart failure is increasing constantly, as 20% of patients in the waiting list die every year. Despite the great need for mechanical heart support systems, using of available systems is limited by the expensiveness. In addition, there is no one system that is 100% responsible to all medical and technical requirements, and would be completely safe for patient. Therefore, further research in the field of circu-latory support systems, considering health and technical requirements is relevant. One of the new directions in the study are disc pumps of viscous friction for liquid transporting, based on the Tesla pump principle. The operation principle of pumps based on the phenomenon of the boundary layer which is formed on the disk rotating in a fluid. There are experimental studies results of models with different variants of the rotor suspension, the various forms and the number of disks, forms the pump housing. However, none of the above samples was not brought to clinical trials. Furthermore, despite the promise of this model is still used today in some circulatory support systems are no similar type pump. Published data provide a basis for further development and testing of the pump model and allow to hope for leveling a number of significant shortcomings of modern left ventricular bypass systems.

  2. Design and evaluation of a single-pivot supported centrifugal blood pump.

    PubMed

    Yoshino, M; Uemura, M; Takahashi, K; Watanabe, N; Hoshi, H; Ohuchi, K; Nakamura, M; Fujita, H; Sakamoto, T; Takatani, S

    2001-09-01

    In order to develop a centrifugal blood pump that meets the requirements of a long-term, implantable circulatory support device, in this study a single-pivot bearing supported centrifugal blood pump was designed to evaluate its basic performance. The single-pivot structure consisted of a ceramic ball male pivot mounted on the bottom surface of the impeller and a polyethylene female pivot incorporated in the bottom pump casing. The follower magnet mounted inside the impeller was magnetically coupled to the driver magnet mounted on the shaft of the direct current brushless motor. As the motor rotated, the impeller rotated supported entirely by a single-pivot bearing system. The static pump performance obtained in the mock circulatory loop revealed an acceptable performance as a left ventricular assist device in terms of flow and head pressure. The pump flow of 5 L/min against the head pressure of 100 mm Hg was obtained at rotational speeds of 2,000 to 2,200 rpm. The maximum pump flow was 9 L/min with 2,200 rpm. The maximum electrical-to-hydraulic power conversion efficiency was around 14% at pump flows of 4 to 5 L/min. The stability of the impeller was demonstrated at the pump rpm higher than 1,400 with a single-pivot bearing without an additional support at its top. The single-pivot supported centrifugal pump can provide adequate flow and pressure as a ventricular assist device, but its mechanical stability and hemolytic as well as thrombotic performances must be tested prior to clinical use.

  3. Survey of advanced-heat-pump developments for space conditioning

    SciTech Connect

    Fairchild, P.D.

    1981-01-01

    A survey of heat pump projects with special emphasis on those supported by DOE, EPRI, and the Gas Research Institute is presented. Some historical notes on heat pump development are discussed. Market and equipment trends, well water and ground-coupled heat pumps, heat-actuated heat pump development, and international interest in heat pumps are also discussed. 30 references.

  4. HeartMate left ventricular assist devices: a multigeneration of implanted blood pumps.

    PubMed

    Maher, T R; Butler, K C; Poirier, V L; Gernes, D B

    2001-05-01

    The HeartMate family of implanted left ventricular assist devices (LVADs) developed by Thermo Cardiosystems, Inc. (TCI) span a time frame that goes back to the beginning of clinical use of mechanical circulatory support and will stretch well into the foreseeable future. Associated blood pump technology employed in the HeartMates range from an original pusher plate concept to the most advanced rotary pump devices. Starting initially with a pneumatic actuated pusher plate pump, clinical use of the HeartMate I began in 1986. In 1990, electric motor-actuated versions of the HeartMate I began to be used clinically. Presently, the HeartMate I has been implanted in some 2,300 patients worldwide, and this LVAD is a standard by which all others are currently measured. Following the HeartMate I is TCI's next-generation, the HeartMate II, a rotary-pump-based LVAD that uses an axial flow blood pump having blood immersed mechanical bearings. Clinical trials of the HeartMate II were initiated in 2000. The HeartMate III, representing TCI's next-generation LVAD, is structured around a centrifugal blood pump that uses a magnetically levitated rotating assembly. Compared to the HeartMate II, the HeartMate III has the potential for higher overall efficiency. The pump's operating life is not dependent on bearing wear. Given the significantly advanced LVAD technology represented by HeartMates II and III, coupled with the experience of HeartMate I, TCI is well-poised to keep its LVAD products as industry standards in the future.

  5. Evaluation of erythrocyte flow at a bearing gap in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Sakota, Daisuke; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2015-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support. In the blood pump, a spiral groove bearing was adopted for a thrust bearing. In the spiral groove bearing, separation of erythrocytes and plasma by plasma skimming has been postulated to occur. However, it is not clarified that plasma skimming occurs in a spiral groove bearing. The purpose of this study is to verify whether plasma skimming occurs in the spiral groove bearing of a hydrodynamically levitated centrifugal blood pump. For evaluation of plasma skimming in the spiral groove bearing, an impeller levitation performance test using a laser focus displacement meter and a microscopic visualization test of erythrocyte flow using a high-speed microscope were conducted. Bovine blood diluted with autologous plasma to adjust hematocrit to 1.0% was used as a working fluid. Hematocrit on the ridge region in the spiral groove bearing was estimated using image analysis. As a result, hematocrits on the ridge region with gaps of 45 μm, 31 μm, and 25 μm were calculated as 1.0%, 0.6%, and 0.3%, respectively. Maximum skimming efficiency in this study was calculated as 70% with a gap of 25 μm. We confirmed that separation of erythrocyte and plasma occurred in the spiral groove bearing with decrease in bearing gap in a hydrodynamically levitated centrifugal blood pump.

  6. [Study on optimal selection of structure of vaneless centrifugal blood pump with constraints on blood perfusion and on blood damage indexes].

    PubMed

    Hu, Zhaoyan; Pan, Youlian; Chen, Zhenglong; Zhang, Tianyi; Lu, Lijun

    2012-12-01

    This paper is aimed to study the optimal selection of structure of vaneless centrifugal blood pump. The optimal objective is determined according to requirements of clinical use. Possible schemes are generally worked out based on structural feature of vaneless centrifugal blood pump. The optimal structure is selected from possible schemes with constraints on blood perfusion and blood damage indexes. Using an optimal selection method one can find the optimum structure scheme from possible schemes effectively. The results of numerical simulation of optimal blood pump showed that the method of constraints of blood perfusion and blood damage is competent for the requirements of selection of the optimal blood pumps.

  7. A novel permanent maglev impeller TAH: most requirements on blood pumps have been satisfied.

    PubMed

    Qian, K X; Zeng, P; Ru, W M; Yuan, H Y

    2003-07-01

    Based on the development of an impeller total artificial heart (TAH) (1987) and a permanent maglev (magnetic levitation) impeller pump (2002), as well as a patented magnetic bearing and magnetic spring (1996), a novel permanent maglev impeller TAH has been developed. The device consists of a rotor and a stator. The rotor is driven radially. Two impellers with different dimensions are fixed at both the ends of the rotor. The levitation of the rotor is achieved by using two permanent magnetic bearings, which have double function: radial bearing and axial spring. As the rotor rotates at a periodic changing speed, two pumps deliver the pulsatile flow synchronously. The volume balance between the two pumps is realized due to self-modulation property of the impeller pumps, without need for detection and control. Because the hemo-dynamic force acting on the left impeller is larger than that on the right impeller, and this force during systole is larger than that during diastole, the rotor reciprocates axially once a cycle. This is beneficial to prevent the thrombosis in the pump. Furthermore, a small flow via the gap between stator and rotor from left pump into right pump comes to a full washout in the motor and the pumps. Therefore, it seems neither mechanical wear nor thrombosis could occur. The previously developed prototype impeller TAH had demonstrated that it could operate in animal experiments indefinitely, if the bearing would not fail to work. Expectantly, this novel permanent magnetic levitation impeller TAH with simplicity, implantability, pulsatility, compatibility and durability has satisfied the most requirements on blood pumps and will have more extensive applications in experiments and clinics.

  8. Tiny magnetic wireless pump: Fabrication of magnetic impeller and magnetic wireless manipulation for blood circulation in legs

    NASA Astrophysics Data System (ADS)

    Kim, Sung Hoon; Yu, Chang Ho; Ishiyama, K.

    2015-05-01

    This paper introduces a wireless pump that uses magnetic wireless manipulation to pump blood in the legs. A compact size and sufficient hydrodynamic performance were the most important requirements. Because the bonded magnet technique allows for a complex shape and various magnetization orientations, we fabricated a magnetic impeller from magnetic SmFeN powder. The impellers demonstrated a magnetic moment of 2772.64 emu and coercive force of 7.55 kOe. Using the impeller, we developed a tiny blood pump with a diameter of 22 mm and height of 6 mm. The pump allows for a maximum flow rate of 2.7 l/min and maximum pump head of approximately 170 mm Hg at a rotating speed of 6000 rpm. This level of hydrodynamic performance is sufficient to circulate blood in the legs. In this paper, we present the magnetic properties of the magnetic impeller and the hydrodynamic performance with wireless operation.

  9. Design and Hemocompatibility Analysis of a Double-Suction Injection Suspension Blood Pump Using Computational Fluid Dynamics Methods.

    PubMed

    Wu, Yue; Zhu, Liangfan; Luo, Yun

    2017-07-26

    The blood pump has become a possible solution to heart diseases. For the prevention of device failure and hemocompatibility problems, a rotary pump with suspended bearing is a preferred solution. In our previous work, a novel injection suspension method has been introduced to levitate the rotor. The suspension method is totally passive. This study aims to apply this suspension method to a double-suction pump, and the property of the pump was investigated using computational fluid dynamics (CFD) methods. The flow field of the pump is simulated based on the SST k-ω turbulent model. The characteristic curves of the pump were calculated. At the nominal working point of 5 L/min, 100 mm Hg, the suspension force acting on the rotor was detected, which could reach 0.46 N with a gap of 150 µm. We compared the pump with a previously developed single-suction injection pump to evaluate the blood compatibility of the double-suction design. The average scalar shear stress values were 3.13 Pa for the double-suction pump and 7.10 Pa for the single-suction pump. Larger volumes in the single-suction pump were exposed to shear stresses higher than 10 Pa. Thresholds for the von Willebrand factor cleavage, platelet activation, and hemolysis were defined to be 9 Pa, 50 Pa, and 150 Pa, respectively. The volume fractions for the double-suction pump are lower for all thresholds. The normalized index of hemolysis (NIH) values for the two pumps were calculated to be 0.008 g/100 L and 0.016 g/100 L. Results proved that the double-suction pump has a better hemocompatibility compared with the single-suction pump. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  10. PIV Investigations of the Flow Field in the Volute of a Rotary Blood Pump

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.; Kadambi, Jaikrishnan R.; Mehta, Mehul; Smith, William A.; Wernet, Mark P.

    2004-01-01

    A full-size acrylic model of a rotary blood pump was developed in order to utilize Particle Image Velocimetry (PIV) to make measurements of the fluid velocities and turbulent stresses throughout the device. The development of an understanding of the hemodynamics within the blood pump is critical to the development and validation of computational models. A blood analog solution, consisting of sodium iodide solution and glycerin, was developed to match physiological kinematic viscosity. The refractive indecies of the fluid, the pump casing and the impeller were matched to facilitate the use of PIV to make velocity measurements. Velocity measurements made in the volute exit/diffuser region are presented for pumps speeds of 3000-3850 rpm. At each speed data were obtained at a physiological pressure of 90 mmHg and at a maximum flow condition. Four hundred data pairs were used for each resultant mean velocity vector value, representing greater than an order of magnitude more data pairs than reported previously in the literature on similar devices and resulting in velocity uncertainty levels of approximately 2.9%.

  11. PIV Investigations of the Flow Field in the Volute of a Rotary Blood Pump

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.; Kadambi, Jaikrishnan R.; Smith, William A.; Wernet, Mark P.

    2004-01-01

    A full-size acrylic model of a rotary blood pump was developed in order to utilize Particle Image Velocimetry (PIV) to make measurements of the fluid velocities and turbulent stresses throughout the device. The development of an understanding of the hemodynamics within the blood pump is critical to the development and validation of computational models. A blood analog solution, consisting of sodium iodide solution and glycerin, was developed to match physiological kinematic viscosity. The refractive indices of the fluid, the pump casing, and the impeller were matched to facilitate the use of PIV to make velocity measurements. Velocity measurements made in the volute exit/diffuser region are presented for pumps speeds of 3000-3850 rpm. At each speed data were obtained at a physiological pressure of 12 kPa and at a maximum flow condition. Four hundred data pairs were used for each resultant mean velocity vector value, representing greater than an order of magnitude more data pairs than reported previously in the literature on similar devices and resulting in velocity uncertainty levels of approximately 22.9%.

  12. An orbiting scroll blood pump without valves or rotating seals.

    PubMed

    Sharp, M K

    1994-01-01

    Valves in blood pumps are expensive and provide modes of failure. Rotating seals offer sites of thrombus formation and infection. In this study, a prototype pump incorporating no valves or rotating seals was constructed and tested. In this device, fluid is pumped by the orbital action of a spiral shaped scroll relative to an identical stationary scroll whose starting axis is rotated 180 degrees with respect to the orbiting scroll. The two scrolls, which are machined integral with scroll plates, form pockets that are filled from the outside and then ejected in the center as the orbiting scroll completes each cycle. The orbiting scroll is driven by a crank mechanism connected to a motor. Fluid is contained in the space around the scrolls by a flexible collar and does not contact the driving mechanism. The prototype pump is approximately 7.6 cm in diameter and 2.5 cm thick and has an orbiting radius of 5.1 mm. The output of the pump was very sensitive to the clearance between the scroll tip and the base of the opposite scroll plate. For a clearance of 51 microns, pressure differences as high as 400 mmHg and flows as high as 7.7 l/min (of water) were produced at 260 rpm. At 450 rpm with a 330 microns clearance, pressure differences as high as 185 mmHg and flows as high as 7.3 l/min resulted. The relationships between pressure difference and flow were very linear in all cases. Volumetric efficiency was as high as 70% and increased with speed.

  13. In vivo experimental testing of a microaxial blood pump for right ventricular support.

    PubMed

    Christiansen, Stefan; Perez-Bouza, Alberto; Reul, Helmut; Autschbach, Rüdiger

    2006-02-01

    The incidence of isolated right ventricular (RV) failure is rare in postcardiotomy patients, but high in patients undergoing implantation of a left ventricular assist device or cardiac transplantation. Therefore, we have developed a new microaxial flow device and report on our first in vivo animal trials. Six healthy adult female sheep weighing 80-90 kg underwent implantation of the microaxial blood pump for partial unloading of the right ventricle. This pump is a miniaturized rotary blood pump with a diameter of only 6.4 mm and a weight of 11 g. The inner volume of the pump is limited to 12 mL, and the inner artificial blood contacting surface is 65 cm(2). The pump consists of a rotor driven by an incorporated brushless direct current motor, the housing of the rotor, the inflow cage, the outflow cannula, and the driveline. At the maximum speed of 32,500 rotations/min, a flow of 6 L/min can be delivered. The inflow and outflow conduit were anastomosed to the right atrium and the main pulmonary artery, respectively. Hemodynamic and echocardiographic data as well as blood samples were measured over the whole test period of 7 days. The hearts and lungs as well as the pump were explanted for a thorough examination at the end of the trial. Systemic arterial blood pressures remained unchanged during the entire test period. RV cardiac output was diminished significantly as demonstrated by the echocardiographic studies. The number of platelets decreased perioperatively, but recovered within the test period. The free hemoglobin was not enhanced postoperatively indicating no significant hemolysis. Liver function was only slightly impaired due to operative reasons (increase in bilirubin on the first postoperative day but normalization within the test period). The pathologic examination revealed some clots at the inflow cage and fibrin depositions on the impeller as well as on the inner surface of the outflow graft without an impairment of pump function. Our results

  14. Plasma Skimming in a Spiral Groove Bearing of a Centrifugal Blood Pump.

    PubMed

    Murashige, Tomotaka; Sakota, Daisuke; Kosaka, Ryo; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2016-09-01

    Plasma skimming is a phenomenon in which discharge hematocrit is lower than feed hematocrit in microvessels. Plasma skimming has been investigated at a bearing gap in a spiral groove bearing (SGB), as this has the potential to prevent hemolysis in the SGB of a blood pump. However, it is not clear whether plasma skimming occurs in a blood pump with the SGB, because the hematocrit has not been obtained. The purpose of this study is to verify plasma skimming in an SGB of a centrifugal blood pump by developing a hematocrit measurement method in an SGB. Erythrocyte observation using a high-speed microscope and a bearing gap measurement using a laser confocal displacement meter was performed five times. In these tests, bovine blood as a working fluid was diluted with autologous plasma to adjust the hematocrit to 1.0%. A resistor was adjusted to achieve a pressure head of 100 mm Hg and a flow rate of 5.0 L/min at a rotational speed of 2800 rpm. Hematocrit on the ridge region in the SGB was measured using an image analysis based on motion image of erythrocytes, mean corpuscular volume, the measured bearing gap, and a cross-sectional area of erythrocyte. Mean hematocrit on the ridge region in the SGB was linearly reduced from 0.97 to 0.07% with the decreasing mean bearing gap from 38 to 21 μm when the rotational speed was changed from 2250 to 3000 rpm. A maximum plasma skimming efficiency of 93% was obtained with a gap of 21 μm. In conclusion, we succeeded in measuring the hematocrit on the ridge region in the SGB of the blood pump. Hematocrit decreased on the ridge region in the SGB and plasma skimming occurred with a bearing gap of less than 30 μm in the hydrodynamically levitated centrifugal blood pump.

  15. Controlled pitch-adjustment of impeller blades for an intravascular blood pump.

    PubMed

    Throckmorton, Amy L; Sciolino, Michael G; Downs, Emily A; Saxman, Robert S; López-Isaza, Sergio; Moskowitz, William B

    2012-01-01

    Thousands of mechanical blood pumps are currently providing circulatory support, and the incidence of their use continues to increase each year. As the use of blood pumps becomes more pervasive in the treatment of those patients with congestive heart failure, critical advances in design features to address known limitations and the integration of novel technologies become more imperative. To advance the current state-of-the-art in blood pump design, this study investigates the inclusion of pitch-adjusting blade features in intravascular blood pumps as a means to increase energy transfer; an approach not explored to date. A flexible impeller prototype was constructed with a configuration to allow for a variable range of twisted blade geometries of 60-250°. Hydraulic experiments using a blood analog fluid were conducted to characterize the pressure-flow performance for each of these twisted positions. The flexible, twisted impeller was able to produce 1-25 mmHg for 0.5-4 L/min at rotational speeds of 5,000-8,000 RPM. For a given twisted position, the pressure rise was found to decrease as a function of increasing flow rate, as expected. Generally, a steady increase in the pressure rise was observed as a function of higher twisted degrees for a constant rotational speed. Higher rotational speeds for a specific twisted impeller configuration resulted in a more substantial pressure generation. The findings of this study support the continued exploration of this unique design approach in the development of intravascular blood pumps.

  16. Testing of a centrifugal blood pump with a high efficiency hybrid magnetic bearing.

    PubMed

    Locke, Dennis H; Swanson, Erik S; Walton, James F; Willis, John P; Heshmat, Hooshang

    2003-01-01

    The purpose of this article is to present test results for a second generation, high efficiency, nonpulsatile centrifugal blood pump that is being developed for use as a left ventricular assist device (LVAD). The LVAD pump uses a hybrid passive-active magnetic bearing support system that exhibits extremely low power loss, low vibration, and high reliability under transient conditions and varying pump orientations. A unique feature of the second generation design configuration is the very simple and direct flow path for both main and washing blood flows. The pump was tested in both vertical and horizontal orientations using a standard flow loop to demonstrate the performance and durability of the second generation LVAD. Steady state and transient orientation pump operating characteristics including pressure, flow, speed, temperatures, vibration, and rotor orientation were measured. During the tests, pump performance was mapped at several operating conditions including points above and below the nominal design of 5 L/min at 100 mm Hg pressure rise. Flow rates from 2 to 7 L/min and pressure rises from 50 to 150 mm Hg were measured. Pump speeds were varied during these tests from 2,500 to 3,500 rpm. The nominal design flow of 5 L/min at 100 mm Hg pressure rise was successfully achieved at the design speed of 3,000 rpm. After LVAD performance testing, both 28 day continuous duty and 5 day transient orientation durability tests were completed without incident. A hydrodynamic backup bearing design feasibility study was also conducted. Results from this design study indicate that an integral hydrodynamic backup bearing may be readily incorporated into the second generation LVAD and other magnetically levitated pump rotors.

  17. In vivo evaluation of a peripheral vascular access axial flow blood pump.

    PubMed

    Wampler, R K; Moise, J C; Frazier, O H; Olsen, D B

    1988-01-01

    More than 80 acute and chronic calf in vivo studies were utilized to develop a 3 L/min axial flow blood pump designed for intraarterial ventricular assist. The 7 mm diameter transvalvular inlet cannula of the cable driven pump receives blood from the left ventricle. The pump then discharges blood into the descending aorta. In the calf, the pump was introduced into the renal aorta. Safety and effectiveness of the device were demonstrated in three control and 21 implanted animals. Blood chemistry results showed an average plasma free hemoglobin of 3 mg/dl for control and 6.7 mg/dl for implanted animals. Platelets were 1.04 X 10(6) and 0.65 X 10(6), respectively, for control and implanted animals. Fibrinogen, BUN, creatinine, and bilirubin were essentially the same for both groups of animals. The hardware was typically free of deposits, and histopathologic examination revealed minimal injury to intracardiac structures, aortic valve leaflets, and aortic intima. The data indicates that the device may provide full support for a failing left ventricle with minimal trauma or risk.

  18. An intraventricular axial flow blood pump integrated with a bearing purge system.

    PubMed

    Yamazaki, K; Kormos, R; Mori, T; Umezu, M; Kameneva, M; Antaki, J; Outa, E; Litwak, P; Kerrigan, J; Tomczak, J

    1995-01-01

    The future development of implantable axial flow blood pumps must address two major issues: mechanically induced hemolysis and shaft seal reliability. The recent revisions to our miniature intraventricular axial flow left ventricular assist device (LVAD) were aimed particularly at addressing these concerns. To improve hemocompatibility, a new impeller has been designed according to the following criteria: 1) gradual pressure rise along the blade chord; 2) minimized local fluid acceleration to prevent cavitation; 3) minimum surface roughness; and 4) radius edges. Subsequent in vitro hemolysis tests conducted with bovine and ovine blood have demonstrated very low hemolysis (normalized index of hemolysis = 0.0051 +/- 0.0047 g/100 L) with this new impeller design. To address the need for a reliable seal, we have developed a purged seal system consisting of a miniature lip seal and ceramic pressure groove journal bearing that also acts as a purge pump. Several spiral grooves formed on the bearing surface provide viscous pumping of the purge fluid, generating more than 3,000 mmHg at 10,000 rpm. This purge flow flushes the lip seal and prevents blood backflow into the bearing. We have found this purge pump to offer several advantages because it is simple, compact, durable, does not require separate actuation, and offers a wide range of flow, depending upon the groove design. In vivo animal tests demonstrated the potential of the purged seal system.

  19. Gas exchange efficiency of an oxygenator with integrated pulsatile displacement blood pump for neonatal patients.

    PubMed

    Schlanstein, Peter C; Borchardt, Ralf; Mager, Ilona; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

    2014-01-01

    Oxygenators have been used in neonatal extracorporeal membrane oxygenation (ECMO) since the 1970s. The need to develop a more effective oxygenator for this patient cohort exists due to their size and blood volume limitations. This study sought to validate the next design iteration of a novel oxygenator for neonatal ECMO with an integrated pulsatile displacement pump, thereby superseding an additional blood pump. Pulsating blood flow within the oxygenator is generated by synchronized active air flow expansion and contraction of integrated silicone pump tubes and hose pinching valves located at the oxygenator inlet and outlet. The current redesign improved upon previous prototypes by optimizing silicone pump tube distribution within the oxygenator fiber bundle; introduction of an oval shaped inner fiber bundle core, and housing; and a higher fiber packing density, all of which in combination reduced the priming volume by about 50% (50 to 27 mL and 41 to 20 mL, respectively). Gas exchange efficiency was tested for two new oxygenators manufactured with different fiber materials: one with coating and one with smaller pore size, both capable of long-term use (OXYPLUS® and CELGARD®). Results demonstrated that the oxygen transfer for both oxygenators was 5.3-24.7 mlO2/min for blood flow ranges of 100-500 mlblood/min. Carbon dioxide transfer for both oxygenators was 3.7-26.3 mlCO2/min for the same blood flow range. These preliminary results validated the oxygenator redesign by demonstrating an increase in packing density and thus in gas transfer, an increase in pumping capacity and a reduction in priming volume.

  20. Prediction of leakage flow in a shrouded centrifugal blood pump.

    PubMed

    Teo, Ji-Bin; Chan, Weng-Kong; Wong, Yew-Wah

    2010-09-01

    This article proposes a phenomenological model to predict the leakage flow in the clearance gap of shrouded centrifugal blood pumps. A good washout in the gap clearance between the rotating impeller surfaces and volute casing is essential to avoid thrombosis. However, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Computational fluid dynamics (CFD) analysis was performed to investigate the leakage flow in a miniaturized shrouded centrifugal blood pump operating at a speed of 2000 rpm. Based on an analytical model derived earlier, a phenomenological model is proposed to predict the leakage flow. The leakage flow rate is found to be proportional to h(α) , where h is the gap size and the exponent α ranges from 2.955 to 3.15 for corresponding gap sizes of 0.2-0.5 mm. In addition, it is observed that α is a linear function of the gap size h. The exponent α compensates for the variation of pressure difference along the circumferential direction as well as inertia effects that are dominant for larger gap clearances. The proposed model displays good agreement with computational results. The CFD analysis also showed that for larger gap sizes, the total leakage flow rate is of the same order of magnitude as the operating flow rate, thus suggesting low volumetric efficiency.

  1. Design of a small centrifugal blood pump with magnetic bearings.

    PubMed

    Jahanmir, Said; Hunsberger, Andrew Z; Ren, Zhaohui; Heshmat, Hooshang; Heshmat, Crystal; Tomaszewski, Michael J; Walton, James F

    2009-09-01

    Design of a blood pump with a magnetically levitated rotor requires rigorous evaluation of the magnetic bearing and motor requirements and analysis of rotor dynamics and hydraulic performance with attention to hemolysis and thrombosis potential. Given the desired geometric dimensions, the required operating speed, flow in both the main and wash flow regions, and magnetic bearing performance, one of several design approaches was selected for a new prototype. Based on the estimated operating speed and clearance between the rotor and stator, the motor characteristics and dimensions were estimated. The motor stiffness values were calculated and used along with the hydraulic loading due to the fluid motion to determine the best design for the axial and radial magnetic bearings. Radial and axial stability of the left ventricular assist device prototype was verified using finite element rotor dynamic analysis. The analysis indicated that the rotor could be completely levitated and spun to the desired operating speed with low power loss and no mechanical contact. In vitro experiments with a mock loop test setup were performed to evaluate the performance of the new blood pump prototype.

  2. A new model of centrifugal blood pump for cardiopulmonary bypass: design improvement, performance, and hemolysis tests.

    PubMed

    Leme, Juliana; Fonseca, Jeison; Bock, Eduardo; da Silva, Cibele; da Silva, Bruno Utiyama; Dos Santos, Alex Eugênio; Dinkhuysen, Jarbas; Andrade, Aron; Biscegli, José F

    2011-05-01

    A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  3. Study of a centrifugal blood pump in a mock loop system.

    PubMed

    Uebelhart, Beatriz; da Silva, Bruno Utiyama; Fonseca, Jeison; Bock, Eduardo; Leme, Juliana; da Silva, Cibele; Leão, Tarcísio; Andrade, Aron

    2013-11-01

    An implantable centrifugal blood pump (ICBP) is being developed to be used as a ventricular assist device (VAD) in patients with severe cardiovascular diseases. The ICBP system is composed of a centrifugal pump, a motor, a controller, and a power supply. The electricity source provides power to the controller and to a motor that moves the pump's rotor through magnetic coupling. The centrifugal pump is composed of four parts: external conical house, external base, impeller, and impeller base. The rotor is supported by a pivot bearing system, and its impeller base is responsible for sheltering four permanent magnets. A hybrid cardiovascular simulator (HCS) was used to evaluate the ICBP's performance. A heart failure (HF) (when the heart increases beat frequency to compensate for decrease in blood flow) was simulated in the HCS. The main objective of this work is to analyze changes in physiological parameters such as cardiac output, blood pressure, and heart rate in three situations: healthy heart, HF, and HF with left circulatory assistance by ICBP. The results showed that parameters such as aortic pressure and cardiac output affected by the HF situation returned to normal values when the ICBP was connected to the HCS. In conclusion, the test results showed satisfactory performance for the ICBP as a VAD.

  4. Noninvasive average flow estimation for an implantable rotary blood pump: a new algorithm incorporating the role of blood viscosity.

    PubMed

    Malagutti, Nicolò; Karantonis, Dean M; Cloherty, Shaun L; Ayre, Peter J; Mason, David G; Salamonsen, Robert F; Lovell, Nigel H

    2007-01-01

    The effect of blood hematocrit (HCT) on a noninvasive flow estimation algorithm was examined in a centrifugal implantable rotary blood pump (iRBP) used for ventricular assistance. An average flow estimator, based on three parameters, input electrical power, pump speed, and HCT, was developed. Data were collected in a mock loop under steady flow conditions for a variety of pump operating points and for various HCT levels. Analysis was performed using three-dimensional polynomial surfaces to fit the collected data for each different HCT level. The polynomial coefficients of the surfaces were then analyzed as a function of HCT. Linear correlations between estimated and measured pump flow over a flow range from 1.0 to 7.5 L/min resulted in a slope of 1.024 L/min (R2=0.9805). Early patient data tested against the estimator have shown promising consistency, suggesting that consideration of HCT can improve the accuracy of existing flow estimation algorithms.

  5. Hemolytic evaluation using polyurethane microcapsule suspensions in circulatory support devices: normalized index of hemolysis comparisons of commercial centrifugal blood pumps.

    PubMed

    Maruyama, Osamu; Yamaguchi, Katsuhiro; Nishida, Masahiro; Onoguchi, Tomio; Tsutsui, Tatsuo; Jikuya, Tomoaki; Yamane, Takashi

    2008-02-01

    We have been developing some types of microcapsule suspensions with polyurethane membranes to evaluate the absolute hemolytic characteristics of the centrifugal blood pumps used in circulatory support devices such as artificial hearts. In order to facilitate/realize hemolysis testing on centrifugal blood pumps that have hemolysis levels as low as those of commercial centrifugal blood pumps, we eliminated capsules with diameters less than 72.2 microm, amounting to 15.4% of all capsules in the conventional suspension (crude suspension [CS]), and adjusted the capsule volume ratio to correspond to a hematocrit of 40%. In this way we succeeded in enhancing the sensitivity of the suspension to microcapsule destruction 61 fold. We used this new suspension (fine suspension [FS]) to perform hemolysis tests on four types of commercial pump with mock circulation systems. Under conditions of 500 mm Hg and 11.2 L/min, we successfully determined the hemolytic characteristics (normalized index of hemolysis [NIH]) of some of the centrifugal blood pumps; the results showed some correlation with those of hemolysis tests on bovine blood and suggest that microcapsule suspensions with polyurethane membranes are useful as standard test solutions for the absolute evaluation of centrifugal blood pumps.

  6. Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps

    PubMed Central

    Park, Marcelo; Mendes, Pedro Vitale; Hirota, Adriana Sayuri; dos Santos, Edzangela Vasconcelos; Costa, Eduardo Leite Vieira; Azevedo, Luciano Cesar Pontes

    2015-01-01

    Objective To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support. Methods Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury. Results This study showed that blood flow/pump rotations ratio variations are dependent on extracorporeal membrane oxygenation blood flow in a positive logarithmic fashion. Blood flow/pump rotation ratio variations are negatively associated with transmembrane pressure (R2 = 0.5 for blood flow = 1500mL/minute and R2 = 0.4 for blood flow = 3500mL/minute, both with p < 0.001) and positively associated with CO2 transfer variations (R2 = 0.2 for sweep gas flow ≤ 6L/minute, p < 0.001, and R2 = 0.1 for sweep gas flow > 6L/minute, p = 0.006), and the blood flow/pump rotation ratio is not associated with O2 transfer variations (R2 = 0.01 for blood flow = 1500mL/minute, p = 0.19, and R2 = - 0.01 for blood flow = 3500 mL/minute, p = 0.46). Conclusion Blood flow/pump rotation ratio variation is negatively associated with transmembrane pressure and positively associated with CO2 transfer in this animal model. According to the clinical situation, a decrease in the blood flow/pump rotation ratio can indicate artificial lung dysfunction without the occurrence of hypoxemia. PMID:26340159

  7. Blood flow/pump rotation ratio as an artificial lung performance monitoring tool during extracorporeal respiratory support using centrifugal pumps.

    PubMed

    Park, Marcelo; Mendes, Pedro Vitale; Hirota, Adriana Sayuri; dos Santos, Edzangela Vasconcelos; Costa, Eduardo Leite Vieira; Azevedo, Luciano Cesar Pontes

    2015-01-01

    To analyze the correlations of the blood flow/pump rotation ratio and the transmembrane pressure, CO2 and O2 transfer during the extracorporeal respiratory support. Five animals were instrumented and submitted to extracorporeal membrane oxygenation in a five-step protocol, including abdominal sepsis and lung injury. This study showed that blood flow/pump rotations ratio variations are dependent on extracorporeal membrane oxygenation blood flow in a positive logarithmic fashion. Blood flow/pump rotation ratio variations are negatively associated with transmembrane pressure (R2 = 0.5 for blood flow = 1500mL/minute and R2 = 0.4 for blood flow = 3500mL/minute, both with p < 0.001) and positively associated with CO2 transfer variations (R2 = 0.2 for sweep gas flow ≤ 6L/minute, p < 0.001, and R2 = 0.1 for sweep gas flow > 6L/minute, p = 0.006), and the blood flow/pump rotation ratio is not associated with O2 transfer variations (R2 = 0.01 for blood flow = 1500mL/minute, p = 0.19, and R2 = - 0.01 for blood flow = 3500 mL/minute, p = 0.46). Blood flow/pump rotation ratio variation is negatively associated with transmembrane pressure and positively associated with CO2 transfer in this animal model. According to the clinical situation, a decrease in the blood flow/pump rotation ratio can indicate artificial lung dysfunction without the occurrence of hypoxemia.

  8. In Vivo Testing of a Novel Blood Pump for Short-Term Extracorporeal Life Support

    PubMed Central

    Teman, Nicholas R; Demos, David S; Bryner, Benjamin S; Faliks, Bradley; Jahangir, Emilia M; Mazur, Daniel E; Rojas-Pena, Alvaro; Bartlett, Robert H; Haft, Jonathan W

    2014-01-01

    Background Centrifugal pumps are increasingly used for temporary mechanical support for the treatment of cardiogenic shock. However, centrifugal pumps can generate excessive negative pressure and are afterload-sensitive. A previously developed modified roller pump mitigates these limitations both in vitro and in preliminary animal experiments. We report the results of intermediate-term testing of our evolving pump technology, known as BioVAD. Methods The BioVAD was implanted in 6 adult male sheep (62.5 ± 3.9 kg), with drainage from the left atrium and reinfusion into the descending aorta. The sheep were monitored for 5 days. Heparin was given during the initial implantation, but no additional anti-coagulation was given. Data collected included hemodynamic status, pump flow and pressures, laboratory values to monitor end-organ function and hemolysis, pathologic specimens to evaluate for thromboembolic events and organ ischemia, and explanted pump evaluation. Results All animals survived the planned experimental duration and there were no pump malfunctions. Mean BioVAD flow was 3.57 ± 0.30 L/min (57.1 cc/kg/min) and mean inlet pressure was -30.51 ± 4.25 mmHg. Laboratory values, including plasma free hemoglobin, creatinine, lactate, and bilirubin levels, remained normal. Three animals had small renal cortical infarcts, but there were no additional thromboembolic events or other abnormalities seen on pathologic examination. No thrombus was identified in the BioVAD blood flow path. Conclusions The BioVAD performed well for five days in this animal model of temporary left ventricular assistance. Its potential advantages over centrifugal pumps may make it applicable for short-term mechanical circulatory support. PMID:24856794

  9. Fault-tolerant strategies for an implantable centrifugal blood pump using a radially controlled magnetic bearing.

    PubMed

    Pai, Chi Nan; Shinshi, Tadahiko

    2011-10-01

    In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5 l/min against 100 mmHg, was achieved using the motor for rotation of the impeller, with contact between the impeller and the stator.

  10. Third-generation blood pumps with mechanical noncontact magnetic bearings.

    PubMed

    Hoshi, Hideo; Shinshi, Tadahiko; Takatani, Setsuo

    2006-05-01

    This article reviews third-generation blood pumps, focusing on the magnetic-levitation (maglev) system. The maglev system can be categorized into three types: (i) external motor-driven system, (ii) direct-drive motor-driven system, and (iii) self-bearing or bearingless motor system. In the external motor-driven system, Terumo (Ann Arbor, MI, U.S.A.) DuraHeart is an example where the impeller is levitated in the axial or z-direction. The disadvantage of this system is the mechanical wear in the mechanical bearings of the external motor. In the second system, the impeller is made into the rotor of the motor, and the magnetic flux, through the external stator, rotates the impeller, while the impeller levitation is maintained through another electromagnetic system. The Berlin Heart (Berlin, Germany) INCOR is the best example of this principle where one-axis control combination with hydrodynamic force achieves high performance. In the third system, the stator core is shared by the levitation and drive coil to make it as if the bearing does not exist. Levitronix CentriMag (Zürich, Switzerland), which appeared recently, employs this concept to achieve stable and safe operation of the extracorporeal system that can last for a duration of 14 days. Experimental systems including HeartMate III (Thoratec, Woburn, MA, U.S.A.), HeartQuest (WorldHeart, Ottawa, ON, Canada), MagneVAD (Gold Medical Technologies, Valhalla, NY, U.S.A.), MiTiHeart (MiTi Heart, Albany, NY, U.S.A.), Ibaraki University's Heart (Hitachi, Japan) and Tokyo Medical and Dental University/Tokyo Institute of Technology's disposable and implantable maglev blood pumps are also reviewed. In reference to second-generation blood pumps, such as the Jarvik 2000 (Jarvik Heart, New York, NY, U.S.A.), which is showing remarkable achievement, a question is raised whether a complicated system such as the maglev system is really needed. We should pay careful attention to future clinical outcomes of the ongoing clinical

  11. Hemocompatibility of a hydrodynamic levitation centrifugal blood pump.

    PubMed

    Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Kosaka, Ryo; Sugiyama, Daisuke; Miyamoto, Yusuke; Kawamura, Hiroshi; Kato, Takahisa; Sano, Takeshi; Okubo, Takeshi; Sankai, Yoshiyuki; Shigeta, Osamu; Tsutsui, Tatsuo

    2007-01-01

    A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding the bearing gap. Thrombus formation in the bearing was examined with in vitro thrombogenesis tests and was reduced by changing the groove shapes to increase the bearing-gap flow to 3% of the external flow. Unnecessary vortices around the vanes were also eliminated by changing the number of vanes from four to six.

  12. Inducer analysis/pump model development

    NASA Technical Reports Server (NTRS)

    Cheng, Gary C.

    1994-01-01

    Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design information in a productive manner. The main goal of this study was to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A finite difference Navier-Stokes flow solver, FDNS, which includes an extended k-epsilon turbulence model and appropriate moving zonal interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. In the present study, three key components of the turbopump, the inducer, impeller, and diffuser, were investigated by the proposed pump model, and the numerical results were benchmarked by the experimental data provided by Rocketdyne. For the numerical calculation of inducer flows with tip clearance, the turbulence model and grid spacing are very important. Meanwhile, the development of the cross-stream secondary flow, generated by curved blade passage and the flow through tip leakage, has a strong effect on the inducer flow. Hence, the prediction of the inducer performance critically depends on whether the numerical scheme of the pump model can simulate the secondary flow pattern accurately or not. The impeller and diffuser, however, are dominated by pressure-driven flows such that the effects of turbulence model and grid spacing (except near leading and trailing edges of blades) are less sensitive. The present CFD pump model has been proved to be an efficient and robust analytical tool for pump design due to its very compact numerical structure (requiring small memory), fast turnaround computing time, and versatility for different geometries.

  13. Inducer analysis/pump model development

    NASA Astrophysics Data System (ADS)

    Cheng, Gary C.

    1994-03-01

    Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design information in a productive manner. The main goal of this study was to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A finite difference Navier-Stokes flow solver, FDNS, which includes an extended k-epsilon turbulence model and appropriate moving zonal interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. In the present study, three key components of the turbopump, the inducer, impeller, and diffuser, were investigated by the proposed pump model, and the numerical results were benchmarked by the experimental data provided by Rocketdyne. For the numerical calculation of inducer flows with tip clearance, the turbulence model and grid spacing are very important. Meanwhile, the development of the cross-stream secondary flow, generated by curved blade passage and the flow through tip leakage, has a strong effect on the inducer flow. Hence, the prediction of the inducer performance critically depends on whether the numerical scheme of the pump model can simulate the secondary flow pattern accurately or not. The impeller and diffuser, however, are dominated by pressure-driven flows such that the effects of turbulence model and grid spacing (except near leading and trailing edges of blades) are less sensitive. The present CFD pump model has been proved to be an efficient and robust analytical tool for pump design due to its very compact numerical structure (requiring small memory), fast turnaround computing time, and versatility for different geometries.

  14. Recent Development in Hydrogen Peroxide Pumped Propulsion

    SciTech Connect

    Ledebuhr, A G; Antelman, D R; Dobie, D W; Gorman, T S; Jones, M S; Kordas, J F; McMahon, D H; Ng, L C; Nielsen, D P; Ormsby, A E; Pittenger, L C; Robinson, J A; Skulina, K M; Taylor, W G; Urone, D A; Wilson, B A

    2004-03-22

    This paper describes the development of a lightweight high performance pump-fed divert and attitude control system (DACS). Increased kinetic Kill Vehicles (KV) capabilities (higher .v and acceleration capability) will especially be needed for boost phase engagements where a lower mass KV DACS enables smaller overall interceptors. To increase KV performance while reducing the total DACS dry mass (<10 kg), requires a design approach that more closely emulates those found in large launch vehicles, where pump-fed propulsion enables high propellant-mass-fraction systems. Miniaturized reciprocating pumps, on a scale compatible with KV applications, offer the potential of a lightweight DACS with both high {Delta}v and acceleration capability, while still enabling the rapid pulsing of the divert thrusters needed in the end-game fly-in. Pumped propulsion uses lightweight low-pressure propellant tanks, as the main vehicle structure and eliminates the need for high-pressure gas bottles, reducing mass and increasing the relative propellant load. Prior work used hydrazine and demonstrated a propellant mass fraction >0.8 and a vehicle propulsion dry mass of {approx}3 kg. Our current approach uses the non-toxic propellants 90% hydrogen peroxide and kerosene. This approach enables faster development at lower costs due to the ease of handling. In operational systems these non-toxic propellants can simplify the logistics for manned environments including shipboard applications. This DACS design configuration is expected to achieve sufficient mass flows to support divert thrusters in the 1200 N to 1330 N (270 lbf to 300 lbf) range. The DACS design incorporates two pairs of reciprocating differential piston pumps (oxidizer and fuel), a warm-gas drive system, compatible bi-propellant thrusters, lightweight valves, and lightweight low-pressure propellant tanks. This paper summarizes the current development status and plans.

  15. Muscle powered blood pump: design and initial test results.

    PubMed

    Trumble, D R; Magovern, J A

    1999-01-01

    A pneumatic ventricular assist device (Sarns/3M) has been redesigned for low volume hydraulic actuation to accommodate muscle powered drive systems. Design modifications include adding a bellows/piston mechanism (to compress the blood sac) and a compliance chamber for volume compensation. A simple prototype device was constructed to measure the efficacy of piston pump actuation and to validate pusher plate design. Device manufacture was affected by removing the drive line housing from the pneumatic pump and replacing it with a piston/bushing mechanism. A convex piston profile was chosen to maximize ejection fraction and minimize device size. Stroke volume was found to be a linear function of piston displacement (approximately 3 ml/mm) and reached a maximum value of 45 ml. Mean compression forces of 46-56 N acting during a 12 mm stroke (2.1 L/min at 60 cycles/min) were sufficient to generate mean afterload pressures of 70-110 mm Hg in a mock circulatory loop. Peak compression forces ranged from 72 to 86 N and work input was calculated to be 552-672 mJ/stroke. These data indicate that this method for delivering muscle power to the bloodstream is both mechanically viable and compatible with the functional capacity of conditioned latissimus dorsi muscle.

  16. Development (design and systematization) of HMS Group pump ranges

    NASA Astrophysics Data System (ADS)

    Tverdokhleb, I.; Yamburenko, V.

    2017-08-01

    The article reveals the need for pump range charts development for different applications and describes main principles used by HMS Group. Some modern approaches to pump selection are reviewed and highlighted the need for pump compliance with international standards and modern customer requirements. Even though pump design types are similar for different applications they need adjustment to specific requirements, which gets manufacturers develop their particular design for each pump range. Having wide pump ranges for different applications enables to create pump selection software, facilitating manufacturers to prepare high quality quotations in shortest time.

  17. Hemolysis generation from a novel, linear positive displacement blood pump for cardiopulmonary bypass on a six kilogram piglet: a preliminary report.

    PubMed

    Lawson, D Scott; Eilers, Derek; Osorio Lujan, Suzanne; Bortot, Maria; Jaggers, James

    2017-05-01

    Current blood pumps used for cardiopulmonary bypass generally fall into two different pump design categories; non-occlusive centrifugal pumps and occlusive, positive-displacement roller pumps. The amount of foreign surface area of extracorporeal circuits correlates with post-operative morbidity due to systemic inflammation, leading to a push for technology that reduces the amount of foreign surfaces. Current roller pumps are bulky and the tubing forms an arc in the pumping chamber (raceway), positioning the inlet 360 degrees from the outlet, making it very difficult to place the pump closer to the patient and to efficiently reduce tubing length. These challenges put existing roller pumps at a disadvantage for use in a compact cardiopulmonary bypass circuit. Centrifugal blood pumps are easier to incorporate into miniature circuit designs. However, the prime volumes of current centrifugal pump designs are large, especially for pediatric extracorporeal circuits where the prime volumes are too great to be of clinical value. We describe a preliminary report on a novel, occlusive, linear, single-helix, positive-displacement blood pump which allows for decreased prime volume and surface area of the extracorporeal circuit. This new experimental pump design was used to perfuse a 6 kilogram piglet with a pediatric cardiopulmonary bypass circuit for two hours of continuous use. Blood samples were obtained every thirty minutes and assayed for plasma free hemolysis generation. The results from this initial experiment showed low plasma free hemoglobin generation and encourages the authors to further develop this concept.

  18. Measurements of enlarged blood pump models using Laser Doppler Anemometer.

    PubMed

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  19. In vivo experimental testing of the FW axial blood pump for left ventricular support in Fu Wai Hospital.

    PubMed

    Zhang, Yan; Hu, Sheng-Shou; Zhou, Jian-Ye; Sun, Han-Song; Tang, Yue; Zhang, Hao; Zheng, Zhe; Li, Guo-Rong; Zhu, Xiao-Dong; Gui, Xin-Min

    2009-01-01

    A fully implantable, axial flow blood pump has been developed in Fu Wai Hospital aiming for clinical use. This ventricular assist device (VAD), which was developed after numerous CFD analyses for the flow characteristics of the pump, is 58.5-mm long, 30-mm wide (including DC motor), and weighs 240 g. The pump can deliver 5 L/min for pressures of 100 mm Hg over 8,000 rpm. In this study, short-term hemocompatibility effects of the axial left ventricular assist device (LVAD) (FW blood pump) were evaluated in four healthy sheep. The device was implanted into the left ventricular apex of beating hearts. The outflow graft of each device was anastomosed to the descending aorta. The hemolysis, which was evaluated in vivo by free hemoglobin value, was below 30 mg/dL. Evaluation of serum biochemical data showed that implantation of the FW blood pump in sheep with normal hearts did not impair end organ function. Gross and microscopic sections of kidney, liver, and lung revealed no evidence of microemboli. Performance of the pump in vivo was considered sufficient for a LVAD, although further design improvement is necessary in terms of hemolysis and antithrombosis to improve biocompatibility of the pump.

  20. Development of a simulated smart pump interface.

    PubMed

    Elias, Beth L; Moss, Jacqueline A; Shih, Alan; Dillavou, Marcus

    2014-01-01

    Medical device user interfaces are increasingly complex, resulting in a need for evaluation in clinicallyaccurate settings. Simulation of these interfaces can allow for evaluation, training, and use for research without the risk of harming patients and with a significant cost reduction over using the actual medical devices. This pilot project was phase 1 of a study to define and evaluate a methodology for development of simulated medical device interface technology to be used for education, device development, and research. Digital video and audio recordings of interface interactions were analyzed to develop a model of a smart intravenous medication infusion pump user interface. This model was used to program a high-fidelity simulated smart intravenous medication infusion pump user interface on an inexpensive netbook platform.

  1. Pulsatile blood pump with a linear drive actuator.

    PubMed

    Fukunaga, Kazuyoshi; Homma, Akihiko; Funakubo, Akio; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Kitamura, Soichiro; Fukui, Yasuhiro

    2007-01-01

    The main purpose of this study was to develop an implantable direct-electromagnetic left ventricular assist system driven by a linear actuator (linear LVAS). The linear LVAS is a pulsatile pump with a pusher plate that is driven directly by a linear oscillatory actuator (LOA) without any movement converters. This prototype pump unit with a LOA was 100 mm in diameter, 50 mm in thickness, and weighed 740 g. The full-fill/full-eject driving method was applied to the control algorithm. In addition, a mechanism to detect and release sucking was realized to overcome this problem that accompanies the active-filling type of VAS. The performance of the linear LVAS was evaluated in a long-term animal experiment using a goat (56 kg). The goat survived for 42 days. The reason why we terminated this experiment was that thrombus was found in the pump. There was no frictional debris found around the LOA. The linear LVAS did not exhibit electrical or mechanical problems during the first animal experiment.

  2. Electro-elastic modeling of a dielectric elastomer diaphragm for a prosthetic blood pump

    NASA Astrophysics Data System (ADS)

    Goulbourne, Nakhiah C.; Frecker, Mary I.; Mockensturm, Eric

    2004-07-01

    A dielectric elastomer diaphragm is to be designed for potential use in a prosthetic blood pump. Application of an electric field deforms the membrane such that it moves from an initially flat configuration to an inflated state. This motion creates positive displacement of blood from the cardiac chambers thus mimicking the pump-like behavior of the natural heart. A comprehensive large deformation model accounting for the combined dielectric and elastic effect has been formulated. This paper presents recent developments in the model to further incorporate the entire nonlinear range of material elastic behavior and to more accurately represent the applied electric field by keeping the voltage constant as the membrane thickness decreases. The updated model is used to calculate the effects of varying system parameters such as pressure, voltage, prestretch, material constants, and membrane geometry. Analytical results are obtained for biaxially stretched 3M VHB 4905 polyacrylate films.

  3. Shape optimization of the diffuser blade of an axial blood pump by computational fluid dynamics.

    PubMed

    Zhu, Lailai; Zhang, Xiwen; Yao, Zhaohui

    2010-03-01

    Computational fluid dynamics (CFD) has been a viable and effective way to predict hydraulic performance, flow field, and shear stress distribution within a blood pump. We developed an axial blood pump with CFD and carried out a CFD-based shape optimization of the diffuser blade to enhance pressure output and diminish backflow in the impeller-diffuser connecting region at a fixed design point. Our optimization combined a computer-aided design package, a mesh generator, and a CFD solver in an automation environment with process integration and optimization software. A genetic optimization algorithm was employed to find the pareto-optimal designs from which we could make trade-off decisions. Finally, a set of representative designs was analyzed and compared on the basis of the energy equation. The role of the inlet angle of the diffuser blade was analyzed, accompanied by its relationship with pressure output and backflow in the impeller-diffuser connecting region.

  4. Dynamic characteristics of a magnetically levitated impeller in a centrifugal blood pump.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2007-04-01

    Centrifugal blood pumps that employ hybrid active/passive magnetic bearings to support noncontact impellers have been developed in order to reduce bearing wear, pump size, the power consumption of the active magnetic bearing, and blood trauma. However, estimates made at the design stage of the vibration of the impeller in the direction of passive suspension during pump operation were inaccurate, because the influence of both the pumping fluid and the rotation of the impeller on the dynamic characteristics was not fully recognized. The purpose of this study is to investigate the dynamic characteristics in a fluid of a magnetically levitated rotating impeller by measuring both the frequency response to sinusoidal excitation of the housing over a wide frequency range and the displacement due to input of a pulsatile flow during left ventricular (LV) assist. The excitation tests were conducted under conditions in which the impeller was levitated in either air or water, and with or without rotation. The experimental and analytical results indicate that vibration of the impeller due to the external force in water was decreased, compared with that in air due to the hydraulic force of water. The axial resonant frequency rose quadratically with rotational speed, and the tilt mode had two resonant frequencies while rotating due to the gyroscopic effect. With the pump inserted into a mock systemic circulatory loop, the dynamic stability of the impeller when pulsatile pressure was applied during LV assist was verified experimentally. The amplitudes of vibration in response to the pulsatile flow in the passively constrained directions were considerably smaller in size than the dimensions of initial gaps between the impeller and the pump housing.

  5. Centrifugal blood pump for temporary ventricular assist devices with low priming and ceramic bearings.

    PubMed

    Leme, Juliana; da Silva, Cibele; Fonseca, Jeison; da Silva, Bruno Utiyama; Uebelhart, Beatriz; Biscegli, José F; Andrade, Aron

    2013-11-01

    A new model of centrifugal blood pump for temporary ventricular assist devices has been developed and evaluated. The design of the device is based on centrifugal pumping principles and the usage of ceramic bearings, resulting in a pump with reduced priming (35 ± 2 mL) that can be applied for up to 30 days. Computational fluid dynamic (CFD) analysis is an efficient tool to optimize flow path geometry, maximize hydraulic performance, and minimize shear stress, consequently decreasing hemolysis. Initial studies were conducted by analyzing flow behavior with different impellers, aiming to determine the best impeller design. After CFD studies, rapid prototyping technology was used for production of pump prototypes with three different impellers. In vitro experiments were performed with those prototypes, using a mock loop system composed of Tygon tubes, oxygenator, digital flow meter, pressure monitor, electronic driver, and adjustable clamp for flow control, filled with a solution (1/3 water, 1/3 glycerin, 1/3 alcohol) simulating blood viscosity and density. Flow-versus-pressure curves were obtained for rotational speeds of 1000, 1500, 2000, 2500, and 3000 rpm. As the next step, the CFD analysis and hydrodynamic performance results will be compared with the results of flow visualization studies and hemolysis tests.

  6. A new design for a compact centrifugal blood pump with a magnetically levitated rotor.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2004-01-01

    A compact centrifugal blood pump has been developed using a radial magnetic bearing with a two-degree of freedom active control. The proposed magnetic bearing exhibits high stiffness, even in passively controlled directions, and low power consumption because a permanent magnet, incorporated with the rotor, suspends its weight. The rotor is driven by a Lorentz force type of built-in motor, avoiding mechanical friction and material wear. The built-in motor is designed to generate only rotational torque, without radial and axial attractive forces on the rotor, leading to low power consumption by the magnetic bearing. The fabricated centrifugal pump measured 65 mm in diameter and 45 mm in height and weighed 0.36 kg. In the closed loop circuit filled with water, the pump provided a flow rate of 4.5 L/min at 2,400 rpm against a pressure head of 100 mm Hg. Total power consumption at that point was 18 W, including 2 W required for magnetic levitation, with a total efficiency of 5.7%. The experimental results showed that the design of the compact magnetic bearing was feasible and effective for use in a centrifugal blood pump.

  7. A durable, non power consumptive, simple seal for rotary blood pumps.

    PubMed

    Mitamura, Y; Sekine, K; Asakawa, M; Yozu, R; Kawada, S; Okamoto, E

    2001-01-01

    One of the key technologic requirements for rotary blood pumps is the sealing of the motor shaft. A mechanical seal, a journal bearing, magnetic coupling, and magnetic suspension have been developed, but they have drawbacks such as wear, thrombus formation, and power consumption. A magnetic fluid seal was developed for an axial flow pump. A magnetic fluid seal is durable, simple, and non power consumptive. Long-term experiments and finite element modeling (FEM) analyses confirmed these advantages. The seal body was composed of a Ned-Fe magnet and two pole pieces; the seal was formed by injecting ferrofluid into the gap (50 microm) between the pole pieces and the motor shaft. To contain the ferrofluid in the seal and to minimize the possibility of ferrofluid making contact with blood, a shield with a small cavity was attached to the pole piece. While submerged in blood, the sealing pressure of the seal was measured and found to be 188 mm Hg with ferrofluid LS-40 (saturated magnetization, 24.3 kA/m) at a motor speed of 10,000 rpm and 225 mm Hg under static conditions. The magnetic fluid seals performed perfectly at a pressure of 100 mm Hg for 594 + days in a static condition, and 51, 39+, and 34+ days at a motor speed of 8,000 rpm. FEM analyses indicated a theoretical sealing pressure of 260 mm Hg. The state of the magnetic fluid in the seal in water was observed with a microscope. Neither splashing of magnetic fluid nor mixing of the magnetic fluid and water was observed. The specially designed magnetic fluid seal for keeping liquids out is useful for axial flow blood pumps. The magnetic fluid seal was incorporated into an intracardiac axial flow pump.

  8. An ultradurable and compact rotary blood pump with a magnetically suspended impeller in the radial direction.

    PubMed

    Masuzawa, T; Kita, T; Okada, Y

    2001-05-01

    A magnetically suspended centrifugal blood pump has been developed with a self-bearing motor for long-term ventricular assist systems. The rotor of the self-bearing motor is not only actively suspended in the radial direction, but also is rotated by an electromagnetic field. The pump has a long lifetime because there are no mechanical parts such as seals and motor bearings. An outer rotor mechanism was adopted for the self-bearing motor. The stator was constructed in the central space of the motor. The rotor shaped thin ring was set at the circumferential space of the stator. Six vanes were extended from the upper surface of the rotor toward the center of the pump to construct an open-type impeller. The outer diameter and the height of the impeller are 63 mm and 34 mm, respectively. The magnetic bearing method and the servomotor mechanism were adopted to levitate and rotate the rotor. Radial movements of the rotor and rotation are controlled actively by using electromagnets in the stator. Axial movement and tilt of the rotor are restricted by passive stability to simplify the control. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was used to examine basic performance of the pump. Maximum flow rate and pressure head were 8 L/min and 200 mm Hg, respectively. Maximum amplitude of radial displacement of the impeller was 0.15 mm. The impeller could be suspended completely without touching the casing wall during the entire pumping process. Power consumption of the pump was only 9.5 W to produce a flow rate of 5 L/min against a pressure head of 100 mm Hg. We conclude that the pump has sufficient performance for the implantable ventricular assist system.

  9. Sealing properties of mechanical seals for an axial flow blood pump.

    PubMed

    Tomioka, J; Mori, T; Yamazaki, K; Koyanagi, H

    1999-08-01

    A miniature intraventricular axial flow blood pump for left ventricular support is under development. One of the key technologies required for such pumps is sealing of the motor shaft. In this study, to prevent blood backflow into the motor side, mechanical seals were developed and their sealing properties investigated. In the experimental apparatus, the mechanical seal separated the bovine blood on the chamber side from the cooling water on the motor side. A leakage of the blood was measured by inductively coupled plasma (ICP) light emission analysis. The rate of hemolysis was measured by the cyanmethemoglobin method. Frictional torque acting on the shaft was measured by a torque transducer. In the experiments, the rotational speed of the shaft was changed from 1,000 to 10,000 rpm, and the contact force of the seal faces was changed from 1.96 to 4.31 N. To estimate lubrication regimes, the Stribeck curve, a diagram of the coefficient of friction against the bearing characteristic G number, was drawn. The results of the experiments showed that both the leakage of blood and the rate of hemolysis were very small. The friction loss was also very small. The mechanical seal was operated in various lubrication regimes, from a fluid lubrication regime to a mixed lubrication regime.

  10. Long-term ex vivo bovine experiments with the Gyro C1E3 centrifugal blood pump.

    PubMed

    Kawahito, Shinji; Maeda, Tomohiro; Motomura, Tadashi; Takano, Tamaki; Nonaka, Kenji; Linneweber, Joerg; Ichikawa, Seiji; Kawamura, Masaki; Glueck, Julie; Fujisawa, Akira; Makinouchi, Kenzo; Nosé, Yukihiko

    2003-01-01

    Centrifugal blood pumps are used widely for cardiopulmonary bypass, as ventricular assist devices, and for extracorporeal membrane oxygenation (ECMO). However, there is no centrifugal blood pump that is suitable for long-term ECMO. The authors developed the Gyro C1E3 centrifugal blood pump (Kyocera Corporation, Kyoto, Japan), which has superior antithrombogenic, antitraumatic, and hydraulic features in comparison with the conventional centrifugal blood pumps. Five ex vivo long-term durability tests of the Gyro C1E3 were performed using healthy miniature calves. The ECMO circuit was composed of a prototype hollow fiber silicone membrane oxygenator and a Gyro C1E3 pump. Venous blood was drained from the left jugular vein of a calf, passed through the oxygenator and infused into the left carotid artery using a Gyro C1E3. Ex vivo studies were performed from 7 to 15 days at a blood flow rate of 1 L/min. During this period, the Gyro C1E3 demonstrated a stable performance without exchanging the pump. Bleeding complications were the major reason for termination of each experiment. Rotational speed was maintained around 2,000 rpm. All five calves demonstrated neither abnormal signs nor abnormal blood examination data throughout the experiment. Neither clot nor thrombus formations were found during the necropsy in the cannula or pump nor were infarctions observed in any of the major organs. In conclusion, the Gyro C1E3 showed a stable and reliable performance during long-term ex vivo bovine experiments under the conditions tested.

  11. A cost-effective extracorporeal magnetically-levitated centrifugal blood pump employing a disposable magnet-free impeller.

    PubMed

    Hijikata, W; Mamiya, T; Shinshi, T; Takatani, S

    2011-12-01

    In the field of rotary blood pumps, contactless support of the impeller by a magnetic bearing has been identified as a promising method to reduce blood damage and enhance durability. The authors developed a two-degrees-of-freedom radial controlled magnetic bearing system without a permanent magnet in the impeller in order that a low-cost disposable pump-head for an extracorporeal centrifugal blood pump could be manufactured more easily. Stable levitation and contactless rotation of the 'magnet-free' impeller were realized for a prototype blood-pump that made use of this magnetic bearing. The run-out of the impeller position at between 1000 r/min and 3000 r/min was less than 40 microm in the radial-controlled directions. The total power consumption of the magnetic bearing was less than 1 W at the same rotational speeds. When the pump was operated, a flow rate of 5 l/min against a head pressure of 78.66 kPa was achieved at a rotational speed of 4000 r/min, which is sufficient for extracorporeal circulation support. The proposed technology offers the advantage of low-cost mass production of disposable pump heads.

  12. Force and torque characteristics for magnetically driven blood pump

    NASA Astrophysics Data System (ADS)

    Zheng, Pan; Haik, Yousef; Kilani, Mohammad; Chen, Ching-Jen

    2002-03-01

    Magnetically driven screw pumps were designed and fabricated for pumping biological fluids. The magnetic field simulations for three different magnetic coupling arrangements were obtained numerically. The force and torque for the three arrangements were computed. The effect of the separation gap between poles and the rotational angle on the force and torque is also presented. The pump characteristics were obtained experimentally.

  13. Concept for a new hydrodynamic blood bearing for miniature blood pumps.

    PubMed

    Kink, Thomas; Reul, Helmut

    2004-10-01

    The most crucial element of a long-term implantable rotary blood pump is the rotor bearing. Because of heat generation and power loss resulting from friction, seals within the devices have to be avoided. Actively controlled magnetic bearings, although maintenance-free, increase the degree of complexity. Hydrodynamic bearings for magnetically coupled rotors may offer an alternative solution to this problem. Additionally, for miniature pumps, the load capacity of hydrodynamic bearings scales slower than that of, for example, magnetic bearings because of the cube-square-law. A special kind of hydrodynamic bearing is a spiral groove bearing (SGB), which features an excellent load capacity. Mock-loop tests showed that SGBs do not influence the hydraulic performance of the tested pumps. Although, as of now, the power consumption of the SBG is higher than for a mechanical pivot bearing, it is absolutely contact-free and has an unlimited lifetime. The liftoff of the rotor occurs already at 10% of design speed. Further tests and flow visualization studies on scaled-up models must demonstrate its overall blood compatibility.

  14. Note: Development of a cryocooler based high efficiency cryosorption pump

    NASA Astrophysics Data System (ADS)

    Verma, Ravi; Chatterjee, Aritra; Kasthurirengan, Srinivasan; Shivaprakash, N. C.; Behera, Upendra

    2017-08-01

    In this communication, we report the development of a cryosorption pump, whose pumping speeds are higher at least by a factor of 1.5 compared to the commercial pumps in specific pressure ranges. This uses a material of high adsorbing capacity along with an adhesive of high thermal conductivity. The measured pumping speeds of these pumps for different gases such as nitrogen, argon, hydrogen, and helium are higher than the commercial cryopumps in the pressure range from 5 × 10-6 mbar to 5 × 10-5 mbar. The developed pump will be quite useful for fusion applications.

  15. Automatic system for noninvasive blood pressure determination in rotary pump recipients.

    PubMed

    Schima, Heinrich; Boehm, Herbert; Huber, Leopold; Schmallegger, Helmut; Vollkron, Michael; Hiesmayr, Michael; Noisser, Robert; Wieselthaler, Georg

    2004-05-01

    In patients with implanted rotary pumps, the arterial pressure pulsatility is usually far lower than in normal individuals. Depending on the remaining degree of pulsatility, cuff-based systems such as the classical Riva-Rocci-determination of arterial blood pressure and correlated sounds or pressure measurements based on cuffpressure oscillations become inaccurate or even impossible. Therefore, a system was developed which evaluates the flow in the radial artery using an ultrasound wristwatch sensor, and this additional information is used for pressure determination. A computerized data acquisition and cuff-control system based on a PC using Matlab software, a wristwatch ultrasound device, and a compressor-driven pressure cuff was set up. The cuff was controlled for automatic inflation and deflation cycles. Cuff pressure and arterial flow was recorded. Several algorithm strategies were developed, which gave data for systolic blood pressure and heart rate together with a reliability index for data quality. Finally, the new algorithms were implemented in a microcontroller system. Comparisons with invasive measurements showed excellent correlation with systolic blood pressure (mean deltaP -0.3 mm Hg, n = 28). During exercise of rotary pump patients and therefore enhanced pulsatility the difference from manual evaluation was -2.1 mm Hg (n = 18). In conclusion, adaptation of the classical cuff-pressure method with ultrasound evaluation of peripheral flow allows reliable determination of blood pressure in patients with low pulsatility resulting from implanted rotary cardiac assist pumps. By development of a wristwatch sensor and an automatic control system a robust method for daily use could be developed.

  16. Evaluation of suction detection during different pumping states in an implantable rotary blood pump.

    PubMed

    Ng, Siew-Cheok; Lim, Einly; Mason, David G; Avolio, Alberto P; Lovell, Nigel H

    2013-08-01

    In recent times, the problem of noninvasive suction detection for implantable rotary blood pumps has attracted substantial research interest. Here, we compare the performance of various suction indices for different types of suction and non-suction events based on pump speed irregularity. A total of 171 different indices that consist of previously proposed as well as newly introduced suction indices are tested using regularized logistic regression. These indices can be classified as amplitude based (derived from the mean, maximum, and minimum values of a cycle), duration based (derived from the duration of a cycle), gradient based (derived from the first order as well as higher order differences) and frequency based (derived from the power spectral density). The non-suction event data consists of ventricular ejection with or without arrhythmia and intermittent and continuous non-opening of the aortic valve. The suction event data consists of partial ventricular collapse that occurs intermittently as well as continuously with or without arrhythmia. In addition, we also attempted to minimize the usage of multiple indices by applying the sequential forward floating selection method to find which combination of indices gives the best performance. In general, the amplitude-based and gradient-based indices performed quite well while the duration-based and frequency-based indices performed poorly. By having only two indices ([i] the maximum gradient change in positive slope; and [ii] the standard deviation of the maximum value in a cycle), we were able to achieve a sensitivity of 98.9% and a specificity of 99.7%.

  17. Solar powered circulation pump development. Final report

    SciTech Connect

    Johnson, A.L.

    1980-09-01

    An iterative design and evaluation process was undertaken to develop a prototype solar powered liquid circulation pump. The first effort was to review the state-of-the-art of liquid piston heat engines. Next a morphological analysis of the original concept was performed. An analysis of the pump performance from a theoretical basis was performed by deriving and solving the equations governing the cycle. The results are documented. An experimental evaluation of the condensing phenomena was performed. The design of the boiler was then undertaken. This effort showed a fundamental physical limitation imposed by the original geometry and the physics of water boiling. In an effort to resolve this problem, a number of alternate configurations were examined, with the result being that the boiler and heat pipe elements of the design were entirely eliminated. In their stead it was assumed that the boiling could be conducted in the solar panel. A number of solar panel designs were examined, and the most appropriate type of solar panel is described in the appendix. A 1/4th scale unit was fabricated and tested. The overall efficiency was approximately 1% at the design point, compared with a theoretical limit of 1.6% for the given operating conditions. The production costs of the full size pump were examined. Finally systems integration aspects were considered and the results presented.

  18. The effects of residual pump blood on patient plasma free haemoglobin levels post cardiac surgery.

    PubMed

    Schotola, H; Wetz, A J; Popov, A F; Bergmann, I; Danner, B C; Schöndube, F A; Bauer, M; Bräuer, A

    2016-09-01

    At the end of cardiopulmonary bypass, there are invariably several hundred millilitres of residual pump blood in the reservoir, which can either be re-transfused or discarded. The objective of this prospective observational study was to investigate the quality of the residual pump blood, focusing on plasma free haemoglobin (pfHb) and blood cell counts. Fifty-one consecutive patients were included in the study. Forty-nine units of residual pump blood and 58 units of transfused red blood cell (RBC) concentrates were analysed. The mean preoperative pfHb of the patients was 0.057 ± 0.062 g/l, which increased gradually to 0.55 ± 0.36 g/l on arrival in the intensive care unit postoperatively. On the first postoperative day, the mean pfHb had returned to within the normal range. Our data showed that haemoglobin, haematocrit, and erythrocyte counts of residual pump blood were approximately 40% of the values in standardised RBC concentrates. Plasma free haemoglobin was significantly higher in residual pump blood compared to RBC concentrates, and nearly twice as high as the pfHb in patient blood samples taken contemporaneously. Our findings indicate that residual pump blood pfHb levels are markedly higher compared to patients' blood and RBC concentrates, but that its administration does not significantly increase patients' pfHb levels.

  19. Parameter estimation and actuator characteristics of hybrid magnetic bearings for axial flow blood pump applications.

    PubMed

    Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh

    2009-07-01

    Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid.

  20. Recent Developments in Magnetically Coupled Vane Pumps for Tritium Service

    SciTech Connect

    Capuder, F. C.; Quigley, L. T.; Baker, C. K.

    1985-04-01

    Despite advances in shaft sealing, a totally reliable shaft seal for two-stage vane pumps has never been developed. Therefore, the magnetically coupled vane pump drive was developed to solve the critical problem of tritium leakage at the shaft seals of vane pumps. As a result, radioactive contamination of the work area and loss of valuable material can now be prevented.

  1. Space nuclear system thermoelectric NaK pump development

    NASA Technical Reports Server (NTRS)

    Johnson, J. L.

    1973-01-01

    The engineering, design, fabrication, and test history of the dual-throat thermoelectric NaK development pump is summarized, along with the engineering and design status of a similar prototype pump intended for use on the 5-kwe reactor thermoelectric system. The history of dc pump development and testing on previous programs is also summarized.

  2. Rotary blood pump control strategy for preventing left ventricular suction.

    PubMed

    Wang, Yu; Koenig, Steven C; Slaughter, Mark S; Giridharan, Guruprasad A

    2015-01-01

    The risk for left ventricular (LV) suction while maintaining adequate perfusion over a range of physiologic conditions during continuous flow LV assist device (LVAD) support is a significant clinical concern. To address this challenge, we developed a suction prevention and physiologic control (SPPC) algorithm for use with axial and centrifugal LVADs. The SPPC algorithm uses two gain-scheduled, proportional-integral controllers that maintain a differential pump speed (ΔRPM) above a user-defined threshold to prevent LV suction, while maintaining an average reference differential pressure (ΔP) between the LV and aorta to provide physiologic perfusion. Efficacy and robustness of the proposed algorithm were evaluated in silico during simulated rest and exercise test conditions for (1) ΔP/ΔRPM excessive setpoint (ES); (2) rapid eightfold increase in pulmonary vascular resistance (PVR); and (3) ES and PVR. Hemodynamic waveforms (LV pressure and volume; aortic pressure and flow) were simulated and analyzed to identify suction event(s), quantify total flow output (pump + cardiac output), and characterize the performance of the SPPC algorithm. The results demonstrated that the proposed SPPC algorithm prevented LV suction while maintaining physiologic perfusion for all simulated test conditions, and warrants further investigation in vivo.

  3. Mathematical Modeling of Rotary Blood Pumps in a Pulsatile In Vitro Flow Environment.

    PubMed

    Pirbodaghi, Tohid

    2017-01-18

    Nowadays, sacrificing animals to develop medical devices and receive regulatory approval has become more common, which increases ethical concerns. Although in vivo tests are necessary for development and evaluation of new devices, nonetheless, with appropriate in vitro setups and mathematical models, a part of the validation process can be performed using these models to reduce the number of sacrificed animals. The main aim of this study is to present a mathematical model simulating the hydrodynamic function of a rotary blood pump (RBP) in a pulsatile in vitro flow environment. This model relates the pressure head of the RBP to the flow rate, rotational speed, and time derivatives of flow rate and rotational speed. To identify the model parameters, an in vitro setup was constructed consisting of a piston pump, a compliance chamber, a throttle, a buffer reservoir, and the CentriMag RBP. A 40% glycerin-water mixture as a blood analog fluid and deionized water were used in the hydraulic circuit to investigate the effect of viscosity and density of the working fluid on the model parameters. First, model variables were physically measured and digitally acquired. Second, an identification algorithm based on regression analysis was used to derive the model parameters. Third, the completed model was validated with a totally different set of in vitro data. The model is usable for both mathematical simulations of the interaction between the pump and heart and indirect pressure measurement in a clinical context.

  4. Evaluation of a volumetric intravenous fluid infusion pump for transfusion of blood components containing red cells.

    PubMed

    Thompson, H W; Lasky, L C; Polesky, H F

    1986-01-01

    A method was devised to evaluate the suitability of an infusion pump for transfusing components containing red cells. With simulated transfusions of units of whole blood tested before or after the expiration date there was no increase in the plasma hemoglobin level in pumped blood compared with blood that was put through a standard blood transfusion set. With outdated units of red cells there was an increased level of plasma hemoglobin after pumping. The increases were greatest at maximum pump rates, but were not statistically or clinically significant. The authors' evaluation indicates that this pump causes minimal damage to the red cells, although care should be exercised when rapidly transfusing red cells with high hematocrit values.

  5. Development of a centrifugal pump with improved antithrombogenicity and hemolytic property for chronic circulatory support.

    PubMed

    Taenaka, Y; Wakisaka, Y; Masuzawa, T; Tatsumi, E; Toda, K; Miyazaki, K; Eya, K; Baba, Y; Nakatani, T; Ohno, T; Nishimura, T; Takano, H

    1996-06-01

    A centrifugal pump with a unique structure has been developed for chronic support. The pump is driven by a magnetic coupling and has no rotating shaft, no seal around the rotating part, and a balancing hole at the center of the impeller and the thrust bearing. The pump was improved in stepwise fashion to realize good antithrombogenicity and low hemolysis. The first pump, the National Cardiovascular Center (NCVC)-0, had an impeller with 4 rectangular and curved vanes; 6 triangularly shaped curved vanes were employed in the second model, the NCVC-1, to reduce trauma to the blood. In the third design, the NCVC-2, the central hole was enlarged, and the thrust bearing shoulder was rounded so that blood washing was enhanced around the impeller; stream lines also were smoothed for improved antithrombogenicity. The hemolytic property of the device was evaluated in vitro with heparinized fresh goat blood; hemolysis indexes of the NCVC-0, -1, and -2 were 0.05, 0.01, and 0.006 g per 100 L, respectively. Antithrombogenicity of the pumps was examined in animal experiments as a left heart bypass device in goals weighing 52-75 kg. Six NCVC-0 pumps were driven for 14 to 33 (22.0 +/- 7.6) days in goats receiving the antiplatelet drug cilostazol orally. Four NCVC-1 pumps ran for 1 to 80 (28.5 +/- 30.6) days with the same drug regimen in 2 cases and with no anticoagulation therapy in 2 cases. After 3 preliminary 1-week tests of NCVC-2 pumps in animals, the pump was installed in 3 goats; 2 pumps were still running on the 182nd and 58th pumping day. Intracorporeal implantation also was attempted successfully. The results indicate that this pump has promising features for chronic support although longer term and additional evaluations are necessary.

  6. Development of a cryogenic capillary pumped loop

    SciTech Connect

    Kroliczek, E.J.; Cullimore, B.

    1996-03-01

    This paper describes the initial development of a promising new cryogenic technology. Room temperature capillary pumped loops (CPLs), a derivative of heat pipe technology, have been under development for almost two decades and are emerging as a design solution for many spacecraft thermal control problems. While cryogenic capillary pumped loops have application to passive spacecraft radiators and to long term storage of cryogenic propellants and open-cycle coolants, their application to the integration of spacecraft cryocoolers has generated the most excitement. Without moving parts or complex controls, they are able to thermally connect redundant cryocoolers to a single remote load, eliminating thermal switches and providing mechanical isolation at the same time. Development of a cryogenic CPL (CCPL) presented some unique challenges including start-up from a super-critical state, the management of parasitic heat leaks and pressure containment at ambient temperatures. These challenges have been overcome with a novel design that requires no additional devices or preconditioning for start-up. This paper describes the design concept and development and results conducted under SBIR Phase I and Phase II. {copyright} {ital 1996 American Institute of Physics.}

  7. A compact highly efficient and low hemolytic centrifugal blood pump with a magnetically levitated impeller.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2006-03-01

    A magnetically levitated (maglev) centrifugal blood pump (CBP), intended for use as a ventricular assist device, needs to be highly durable and reliable for long-term use without any mechanical failure. Furthermore, maglev CBPs should be small enough to be implanted into patients of various size and weight. We have developed a compact maglev CBP employing a two-degree-of-freedom controlled magnetic bearing, with a magnetically suspended impeller directly driven by an internal brushless direct current (DC) motor. The magnetic bearing actively controls the radial motion of the impeller and passively supports axial and angular motions using a permanent magnet embedded in the impeller. The overall dimensions of the maglev CBP are 65 mm in diameter and 40 mm in height. The total power consumption and pump efficiency for pumping 6 L/min against a head pressure of 105 mm Hg were 6.5 W and 21%, respectively. To evaluate the characteristics of the maglev CBP when subjected to a disturbance, excitation of the base, simulating the movement of the patient in various directions, and the sudden interception of the outlet tube connected with the pump in a mock circulatory loop, simulating an unexpected kink and emergent clamp during a heart surgery, were tested by monitoring the five-degree-of-freedom motion of the impeller. Furthermore, the hemolytic characteristics of the maglev CBP were compared with those of the Medtronic Biomedicus BPX-80, which demonstrated the superiority of the maglev CBP.

  8. Noninvasive average flow and differential pressure estimation for an implantable rotary blood pump using dimensional analysis.

    PubMed

    Lim, Einly; Karantonis, Dean M; Reizes, John A; Cloherty, Shaun L; Mason, David G; Lovell, Nigel H

    2008-08-01

    Accurate noninvasive average flow and differential pressure estimation of implantable rotary blood pumps (IRBPs) is an important practical element for their physiological control. While most attempts at developing flow and differential pressure estimate models have involved purely empirical techniques, dimensional analysis utilizes theoretical principles of fluid mechanics that provides valuable insights into parameter relationships. Based on data obtained from a steady flow mock loop under a wide range of pump operating points and fluid viscosities, flow and differential pressure estimate models were thus obtained using dimensional analysis. The algorithm was then validated using data from two other VentrAssist IRBPs. Linear correlations between estimated and measured pump flow over a flow range of 0.5 to 8.0 L/min resulted in a slope of 0.98 ( R(2) = 0.9848). The average flow error was 0.20 +/- 0.14 L/min (mean +/- standard deviation) and the average percentage error was 5.79%. Similarly, linear correlations between estimated and measured pump differential pressure resulted in a slope of 1.027 ( R(2) = 0.997) over a pressure range of 60 to 180 mmHg. The average differential pressure error was 1.84 +/- 1.54 mmHg and the average percentage error was 1.51%.

  9. Twisted cardiovascular cages for intravascular axial flow blood pumps to support the Fontan physiology.

    PubMed

    Throckmorton, Amy L; Downs, Emily A; Hazelwood, John A; Monroe, Jonathan O; Chopski, Steven G

    2012-05-01

    Failing single ventricle physiology represents an ongoing challenge in mechanical assist device development, requiring pressure augmentation in the cavopulmonary circuit, reduction of systemic venous pressure, and increased cardiac output to achieve hemodynamic stabilization. To meet these requirements, we are developing a percutaneously-placed, axial flow blood pump to support ailing single ventricle physiology in adolescents and adults. We have modified the outer cage of the device to serve as both a protective and functional design component. This study examined the performance of 3 cage geometries with varying directions of filament twist using numerical simulations and hydraulic experiments. All 3 cage and pump models performed in acceptable ranges to support Fontan patients. The cage design employing filaments that are twisted in the opposite direction to the impeller blades and in the direction of the diffuser blades (against-with) demonstrated superior performance by generating a pressure rise range of 5-38 mmHg of flow rates of 0.5-6 l/min at rotational speeds of 5000-7000 rpm. The blood damage indices for all of the cages were found to be well below 2%, and the scalar stress levels were below 200 Pa. This study represents ongoing progress in the development of the impeller and cage assembly. Validation of the results will continue in experiments with blood bag evaluation as well as by particle image velocimetry measurements.

  10. Development of an algorithm to regulate pump output for a closed air-loop type pneumatic biventricular assist device.

    PubMed

    Nam, Kyoung Won; Lee, Jung Joo; Hwang, Chang Mo; Choi, Jaesoon; Choi, Hyuk; Choi, Seong Wook; Sun, Kyung

    2009-12-01

    The closed air space-type of extracorporeal pneumatic ventricular assist device (VAD) developed by the Korea Artificial Organ Center utilizes a bellows-transforming mechanism to generate the air pressure required to pump blood. This operating mechanism can reduce the size and weight of the driving unit; however, the output of the blood pump can be affected by the pressure loading conditions of the blood sac. Therefore, to guarantee a proper pump output level, regardless of the pressure loading conditions that vary over time, automatic pump output regulation of the blood pump is required. We describe herein a pump output regulation algorithm that was developed to maintain pump output around a reference level against various afterload pressures, and verified the pump performance in vitro. Based on actual operating conditions in animal experiments, the pumping rate was limited to 40-84 beats per minute, and the afterload pressure was limited to 80-150 mm Hg. The tested reference pump output was 4.0 L/min. During experiments, the pump output was successfully and automatically regulated within the preset area regardless of the varying afterload conditions. The results of this preliminary experiment can be used as the basis for an automatic control algorithm that can enhance the stability and reliability of the applied VAD.

  11. Numerical, hydraulic, and hemolytic evaluation of an intravascular axial flow blood pump to mechanically support Fontan patients.

    PubMed

    Throckmorton, Amy L; Kapadia, Jugal Y; Chopski, Steven G; Bhavsar, Sonya S; Moskowitz, William B; Gullquist, Scott D; Gangemi, James J; Haggerty, Christopher M; Yoganathan, Ajit P

    2011-01-01

    Currently available mechanical circulatory support systems are limited for adolescent and adult patients with a Fontan physiology. To address this growing need, we are developing a collapsible, percutaneously-inserted, axial flow blood pump to support the cavopulmonary circulation in Fontan patients. During the first phase of development, the design and experimental evaluation of an axial flow blood pump was performed. We completed numerical modeling of the pump using computational fluid dynamics analysis, hydraulic testing of a plastic pump prototype, and blood bag experiments (n=7) to measure the levels of hemolysis produced by the pump. Statistical analyses using regression were performed. The prototype with a 4-bladed impeller generated a pressure rise of 2-30 mmHg with a flow rate of 0.5-4 L/min for 3000-6000 RPM. A comparison of the experimental performance data to the numerical predictions demonstrated an excellent agreement with a maximum deviation being less than 6%. A linear increase in the plasma-free hemoglobin (pfHb) levels during the 6-h experiments was found, as desired. The maximum pfHb level was measured to be 21 mg/dL, and the average normalized index of hemolysis was determined to be 0.0097 g/100 L for all experiments. The hydraulic performance of the prototype and level of hemolysis are indicative of significant progress in the design of this blood pump. These results support the continued development of this intravascular pump as a bridge-to-transplant, bridge-to-recovery, bridge-to-hemodynamic stability, or bridge-to-surgical reconstruction for Fontan patients.

  12. Development of a compact, highly efficient, totally implantable motor-driven assist pump system.

    PubMed

    Okamoto, E; Tomoda, K; Yamamoto, K; Mitamura, Y; Mikami, T

    1994-12-01

    We have developed a compact, highly efficient, totally implantable assist pump system, which consists of a motor-driven assist pump and a transcutaneous energy and optical information transmission system. The motor-driven assist pump consists of a.d.c. brushless motor and a specially designed miniature ball screw. A magnetic coupling mechanism between the blood pump and an actuator provides active blood filling via mild suction force. The controller consists of a PID follow-up controller using an 8-bit one-chip microcomputer. The volume of the pump is 350 ml, and its controller is 210 ml. Pump outflow of 5.8 L/min was obtained against a mean after-load of 100 mm Hg. The pump showed a high efficiency rate and good durability. An efficiency rate of 19-21% (pump output/motor input) was obtained during 87 days of continuous pumping. No mechanical trouble occurred for an accumulated period of 6 months.

  13. Numerical analysis of the internal flow field in screw centrifugal blood pump based on CFD

    NASA Astrophysics Data System (ADS)

    Han, W.; Han, B. X.; Y Wang, H.; Shen, Z. J.

    2013-12-01

    As to the impeller blood pump, the high speed of the impeller, the local high shear force of the flow field and the flow dead region are the main reasons for blood damage. The screw centrifugal pump can effectively alleviate the problems of the high speed and the high shear stress for the impeller. The softness and non-destructiveness during the transfer process can effectively reduce the extent of the damage. By using CFD software, the characteristics of internal flow are analyzed in the screw centrifugal pump by exploring the distribution rules of the velocity, pressure and shear deformation rate of the blood when it flows through the impeller and the destructive effects of spiral blades on blood. The results show that: the design of magnetic levitation solves the sealing problems; the design of regurgitation holes solves the problem of the flow dead zone; the magnetic levitated microcirculation screw centrifugal pump can effectively avoid the vortex, turbulence and high shear forces generated while the blood is flowing through the pump. Since the distribution rules in the velocity field, pressure field and shear deformation rate of the blood in the blood pump are comparatively uniform and the gradient change is comparatively small, the blood damage is effectively reduced.

  14. Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field.

    PubMed

    Pinotti, M; Paone, N

    1996-06-01

    A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.

  15. [Numerical assessment of impeller features of centrifugal blood pump based on fast hemolysis approximation model].

    PubMed

    Shou, Chen; Guo, Yongjun; Su, Lei; Li, Yongqian

    2014-12-01

    The impeller profile, which is one of the most important factors, determines the creation of shear stress which leads to blood hemolysis in the internal flow of centrifugal blood pump. The investigation of the internal flow field in centrifugal blood pump and the estimation of the hemolysis within different impeller profiles will provide information to improve the performance of centrifugal blood pump. The SST kappa-omega with low Reynolds correction was used in our laboratory to study the internal flow fields for four kinds of impellers of centrifugal blood pump. The flow fields included distributions of pressure field, velocity field and shear stress field. In addition, a fast numerical hemolysis approximation was adopted to calculate the normalized index of hemolysis (NIH). The results indicated that the pressure field distribution in all kinds of blood pump were reasonable, but for the log spiral impeller pump, the vortex and backflow were much lower than those of the other pumps, and the high shear stress zone was just about 0.004%, and the NIH was 0.0089.

  16. In Vitro Testing of a Novel Blood Pump Designed for Temporary Extracorporeal Support

    PubMed Central

    Spurlock, DJ; Ranney, DN; Fracz, E; Mazur, DE; Bartlett, RH; Haft, JW

    2012-01-01

    Extracorporeal blood pumps are used as temporary ventricular assist devices or for extracorporeal membrane oxygenation. The ideal pump would be intrinsically self-regulating, carry no risk of cavitation or excessive inlet suction, be afterload insensitive, and valveless thus reducing thrombogenicity. Currently used technology, including roller, centrifugal, and pneumatic pulsatile pumps, does not meet these requirements. We studied a non-occlusive peristaltic pump (M-Pump) in two mock circulatory loops, and compared the performance to a frequently used centrifugal pump and a modified prototype of the M-Pump (the BioVAD). The simple resistance loop consisted of the investigated pump, a fixed height reservoir at 150 mmHg, and a variable inflow reservoir. The pulsatile circulation utilized a mock patient simulator with adjustable resistance elements connected to a pneumatic pulsatile pump. The M-Pump intrinsically regulated flow with changing preload, was afterload insensitive, and did not cavitate, unlike the centrifugal pump. The BioVAD also demonstrated these features, and could augment output with use of vacuum assistance. A non-occlusive peristaltic pump may be superior for short term extracorporeal circulatory assist by mitigating risks of excessive inlet suction, afterload sensitivity, and thrombosis. PMID:22236624

  17. In vitro testing of a novel blood pump designed for temporary extracorporeal support.

    PubMed

    Spurlock, David J; Ranney, David N; Fracz, Emilia M; Mazur, Daniel E; Bartlet, R H; Haft, Jonathan W

    2012-01-01

    Extracorporeal blood pumps are used as temporary ventricular assist devices or for extracorporeal membrane oxygenation. The ideal pump would be intrinsically self-regulating, carry no risk of cavitation or excessive inlet suction, be afterload insensitive, and valveless thus reducing thrombogenicity. Currently used technology, including roller, centrifugal, and pneumatic pulsatile pumps, does not meet these requirements. We studied a nonocclusive peristaltic pump (M-Pump) in two mock circulatory loops and compared the performance to a frequently used centrifugal pump and a modified prototype of the M-Pump (the BioVAD). The simple resistance loop consisted of the investigated pump, a fixed height reservoir at 150 mm Hg, and a variable inflow reservoir. The pulsatile circulation used a mock patient simulator with adjustable resistance elements connected to a pneumatic pulsatile pump. The M-Pump intrinsically regulated flow with changing preload, was afterload insensitive, and did not cavitate, unlike the centrifugal pump. The BioVAD also demonstrated these features and could augment output with the use of vacuum assistance. A nonocclusive peristaltic pump may be superior for short-term extracorporeal circulatory assist by mitigating risks of excessive inlet suction, afterload sensitivity, and thrombosis.

  18. Evaluation of performance parameters of indigenously developed roots pumping system

    NASA Astrophysics Data System (ADS)

    Maqsood, M.; Usman, A.; Bodla, M. F.; Ali, J.

    2016-08-01

    Roots pumping systems are widely used in industries to generate vacuum with high pumping speed. In the present work, the performance parameters of indigenously developed Roots pumping system have been studied. The performance parameters being studied are the ultimate pressure, working temperature, compression ratio and pumping speed. Ultimate pressure of the Roots pump after continuous running of eight hours is found to be 1.1x10-3 mbar. The most important parameter of the roots pump is the zero-gas flow compression Ratio (Ko) which is found to be 18 for the pumping system under study. Efficiency of Roots pump is found to be 76% which is in good agreement as reported in the literature.

  19. Magnetic drive system for a new centrifugal rotary blood pump.

    PubMed

    Hilton, Andrew; Tansley, Geoff

    2008-10-01

    The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60 degrees included out-lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, Ø, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, theta. The test was repeated for three backing conditions: (i) non-backed; (ii) steel-cupped; and (iii) steel plate back-iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12-magnet configuration at 0 degree cone angle with steel-back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s(2) shock excitation on the impeller. Although the 12 magnet 0 degree (theta) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics.

  20. Noninvasive blood-flow meter using a curved cannula with zero compensation for an axial flow blood pump.

    PubMed

    Kosaka, Ryo; Fukuda, Kyohei; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2013-01-01

    In order to monitor the condition of a patient using a left ventricular assist system (LVAS), blood flow should be measured. However, the reliable determination of blood-flow rate has not been established. The purpose of the present study is to develop a noninvasive blood-flow meter using a curved cannula with zero compensation for an axial flow blood pump. The flow meter uses the centrifugal force generated by the flow rate in the curved cannula. Two strain gauges served as sensors. The first gauges were attached to the curved area to measure static pressure and centrifugal force, and the second gauges were attached to straight area to measure static pressure. The flow rate was determined by the differences in output from the two gauges. The zero compensation was constructed based on the consideration that the flow rate could be estimated during the initial driving condition and the ventricular suction condition without using the flow meter. A mock circulation loop was constructed in order to evaluate the measurement performance of the developed flow meter with zero compensation. As a result, the zero compensation worked effectively for the initial calibration and the zero-drift of the measured flow rate. We confirmed that the developed flow meter using a curved cannula with zero compensation was able to accurately measure the flow rate continuously and noninvasively.

  1. [Research on the feasibility of a magnetic-coupling-driven axial flow blood pump].

    PubMed

    Yu, Xiaoqing; Ding, Wenxiang; Wang, Wei; Chen, En; Jiang, Zuming; Zou, Wenyan

    2004-02-01

    A new-designed axial flow blood pump, dived by magnetic coupling and using internal hollow brushless DC motor and inlet and outlet in line with impeller, was tested in mimic circuit. The results showed good performance of the new pump and indicated that its hydrodynamic characteristic can meet the demands of clinical extracorporeal circulation and auxiliary circulation.

  2. Development of a hybrid chemical/mechanical heat pump

    NASA Technical Reports Server (NTRS)

    Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

    1991-01-01

    The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

  3. Development of a hybrid chemical/mechanical heat pump

    NASA Technical Reports Server (NTRS)

    Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

    1991-01-01

    The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

  4. Elementary theory of synchronous arterio-arterial blood pumps

    NASA Technical Reports Server (NTRS)

    Jones, R. T.; Petscheck, H. E.; Kantrowitz, A. R.

    1976-01-01

    In the technique of arterio-arterial pumping, a volume of fluid is withdrawn from the aorta during systole and reinjected during diastole, thereby reducing the systolic pressure of the heart and adding energy to the systemic circulation. It is found that an upper bound for the effectiveness of such devices is given by a formula that considers stroke output of the unaided heart and the increment caused by the pump with a stroke. The division of effort of the pump between the reduction of pressure and the increase of flow depends on the physiological mechanical impedance of the heart. The total effect is, however, independent of the impedance.

  5. Sensorless Viscosity Measurement in a Magnetically-Levitated Rotary Blood Pump.

    PubMed

    Hijikata, Wataru; Rao, Jun; Abe, Shodai; Takatani, Setsuo; Shinshi, Tadahiko

    2015-07-01

    Controlling the flow rate in an implantable rotary blood pump based on the physiological demand made by the body is important. Even though various methods to estimate the flow rate without using a flow meter have been proposed, no adequate method for measuring the blood viscosity, which is necessary for an accurate estimate of the flow rate, without using additional sensors or mechanisms in a noninvasive way, has yet been realized. We have developed a sensorless method for measuring viscosity in magnetically levitated rotary blood pumps, which requires no additional sensors or mechanisms. By applying vibrational excitation to the impeller using a magnetic bearing, we measured the viscosity of the working fluid by measuring the phase difference between the current in the magnetic bearing and the displacement of the impeller. The measured viscosity showed a high correlation (R(2)  > 0.992) with respect to a reference viscosity. The mean absolute deviation of the measured viscosity was 0.12 mPa·s for several working fluids with viscosities ranging from 1.18 to 5.12 mPa·s. The proposed sensorless measurement method has the possibility of being utilized for estimating flow rate.

  6. Custom Unit Pump Development for the EVA PLSS

    NASA Technical Reports Server (NTRS)

    Schuller, Michael; Kurwitz, Cable; Little, Frank; Oinuma, Ryoji; Larsen, Ben; Goldman, Jeff; Reinis, Filip; Trevino, Luis

    2010-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design and test a pre-flight prototype pump for use in the Extra-vehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump must accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting non-condensable gas without becoming air locked. The chosen pump design consists of a 28 V DC, brushless, seal-less, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES verified that the pump meets the design requirements for range of flow rates, pressure drop, power consumption, working fluid temperature, operating time, gas ingestion, and restart capability under both ambient and vacuum conditions. The pump operated at 40 to 240 lbm/hr flow rate, 35 to 100 oF pump temperature, and 5 to 10 psid pressure rise. Power consumption of the pump controller at the nominal operating point in both ambient and vacuum conditions was 9.5 W, which was less than the 12 W predicted. Gas ingestion capabilities were tested by injecting 100 cc of air into the fluid line; the pump operated normally throughout this test.

  7. Computational fluid dynamics of gap flow in a biocentrifugal blood pump.

    PubMed

    Chua, Leok Poh; Song, Guoliang; Yu, Simon Ching Man; Lim, Tau Meng

    2005-08-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial heart pumps. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and the stationary pump housing inner surface. In this study, numerical simulations were carried out to investigate the flow fields in the gap of the Kyoto-NTN centrifugal blood pump. The flow patterns in the gap region of the blood pump were presented and regions of high and low velocity were identified. It was found that the radial velocity of the blood in the gap was closely related to the pressure distribution at the exit of the impeller, both the highest pressure gradient and the highest radial velocity in the gap occurred at an angular position of 170 degrees . The mass flow rate in the gap was estimated to be 25.2% of the pump outflow, which is close to the measurement results of a five times enlarged test pump. The wall shear stresses on the gap surface were found to be over 21 Pa and below 300 Pa, which is correspondingly higher than the threshold of thrombi formation and is lower than the shearing threshold of red blood cells. Comparison of the 1 : 1 simulation model with the measurement results on a five times enlarged test pump indicates that there are some differences in the resulting radial velocity distributions in the gap and thus the washout mechanism. Two symmetrical high washout regions at both the cutwater and splitter plate were observed in the simulation instead of a single washout region at the splitter plate found in the experimental study. This may be due to the scaling effect of the enlarged test pump; also the medium used in the experiment is different from the simulation.

  8. Noninvasive deadbeat control of an implantable rotary blood pump: a simulation study.

    PubMed

    Lim, E; Alomari, A H; Savkin, A V; Lovell, N H

    2009-01-01

    A deadbeat controller has been proposed for the control of pulsatile pump flow in an implantable rotary blood pump (IRBP). A lumped parameter model of the cardiovascular system, in combination with the stable dynamical models of pulsatile flow and differential pressure (head) estimation for the IRBP was used to evaluate the controller. Pump speed and current were used as the only measured variables of the control system. The control algorithm was tested using both constant and sinusoidal reference pump flow input, under healthy and heart failure conditions. Results showed that the controller is able to track the reference input with minimal error in the presence of model uncertainty.

  9. Development of the Valvo pump: an axial flow pump implanted at the heart valve position.

    PubMed

    Mitamura, Y; Nakamura, H; Okamoto, E; Yozu, R; Kawada, S; Kim, D W

    1999-06-01

    Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized index of hemolysis (NIH) was 0.030 +/- 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis.

  10. Experimental testing of a new left ventricular assist device--the microdiagonal blood pump.

    PubMed

    Christiansen, Stefan; Demircan, Lütfü; Kwant, Paul B; Akdis, Mustafa; Rex, Steffen; Buhre, Wolfgang; Langebartels, Georg; Kuruc, Norbert; Nikolin, Stefan; Reul, Helmut; Autschbach, Rüdiger

    2004-01-01

    All existing ventricular assist devices are associated with a considerable number of serious complications. This article reports on the first animal tests with a newly developed microdiagonal blood pump (MDP). Six adult female sheep weighing 80 to 90 kg underwent implantation of the microdiagonal blood pump. The inflow and outflow conduits were anastomosed to the left atrium and the descending aorta. Pump flow was adjusted to 2-3 L/minute. Hemodynamic and echocardiographic data, as well as blood samples, were measured over the entire test period of 7 days. All internal organs and the pump were explanted for thorough examination at the end of the trial. Mean arterial (range 88.5 +/- 13.1-103.7 +/- 10.7 mm Hg) and mean pulmonary arterial (18.3 +/- 2.7-21.6 +/- 20.5 mm Hg) pressures, as well as the pulmonary capillary wedge pressure (14.2 +/- 3.0 - 16.6 +/- 4.0 mm Hg), remained stable during the whole test period. Cardiac output (4.9 +/- 0.7 --> 3.2 +/- 0.5 L/minute) decreased postoperatively caused by partial unloading of the heart. Left ventricular end diastolic (4.1 +/- 0.5 --> 3.6 +/- 0.3 cm) and end systolic (3.2 +/- 0.4 --> 2.8 +/- 0.5 cm) diameters, as well as the ejection fraction (57 +/- 9 --> 42 +/- 5%), decreased after MDP implantation and did not change during the test period. Mean number of platelets (428 +/- 54 --> 286 +/- 66 x 10(3)/microL) and hemoglobin (9.8 +/- 1.3 --> 6.3 +/- 0.8 g/dL) decreased perioperatively because of surgical reasons and increased continuously in the postoperative course (platelet count and hemoglobin on day 7:441 +/- 74 x 10(3)/microL and 7.2 +/- 1.1 g/dL, respectively). Free hemoglobin was not enhanced in the postoperative course (mean value during the test period: 18.8 mmoL/L). Histologic examination of the organs did not demonstrate any infarctions of internal organs other than typical operative sequelae such as chronic pericarditis and some degree of atelectasis of the left lungs. These results demonstrate that the

  11. First clinical experience with an automatic control system for rotary blood pumps during ergometry and right-heart catheterization.

    PubMed

    Schima, Heinrich; Vollkron, Michael; Jantsch, Ursula; Crevenna, Richard; Roethy, Wilfried; Benkowski, Robert; Morello, Gino; Quittan, Michael; Hiesmayr, Michael; Wieselthaler, Georg

    2006-02-01

    At present, most clinically implanted rotary blood pumps are operated at constant speed and adjusted by the physician. It is generally assumed that an adaptation of pump speed to the patient's physiologic requirements would be beneficial. The data provided in this paper, based on hemodynamic and spirometric data during exercise in which a pre-load-sensitive control was used, lend quantitative support to this assumption. An automatic speed control was developed and implemented with Matlab on a dSpace controller board. The system uses pump speed, pump power, and pump flow as its only input signals. It was connected to the clinical hardware of the DeBakey VAD System. The control is pre-load-sensitive and uses an expert system to detect excessive unloading and eventual suction. This system was used to quantify the cardiovascular reaction of patients to both automatically controlled and constant pump speed. A sub-group of 5 patients underwent bicycle ergometry with Swan-Ganz catheterization and spiroergometry. The automatic, closed-loop speed control showed robust and stable performance. It provided an increase in pump flow (+0.94 +/- 0.5 liters/min, p < 0.05) compared with constant-speed mode in response to physical activity. Pulmonary arterial (PAP) and capillary wedge pressure (PCWP) clearly decreased (-7.4 +/- 4.1 mm Hg for PAP and -8.3 +/- 4.2 mm Hg for PCWP, p < 0.05), and venous oxygen saturation moderately increased (+5.2%). An automatic speed-control system for rotary blood pumps was developed and demonstrated by spiroergometry to be appropriately responsive to physiologic demand.

  12. A sliding mode-based starling-like controller for implantable rotary blood pumps.

    PubMed

    Bakouri, Mohsen A; Salamonsen, Robert F; Savkin, Andrey V; AlOmari, Abdul-Hakeem H; Lim, Einly; Lovell, Nigel H

    2014-07-01

    Clinically adequate implementation of physiological control of a rotary left ventricular assist device requires a sophisticated technique such as the recently proposed method based on the Frank-Starling mechanism. In this mechanism, the stroke volume of the heart increases in response to an increase in the volume of blood filling the left ventricle at the end of diastole. To emulate this process, changes in pump speed need to automatically regulate pump flow to ensure that the combined output of the left ventricle and pump match the output of the right ventricle across changing cardiovascular states. In this approach, we exploit the linear relationship between estimated mean pump flow (Q ̅ est) and pump flow pulsatility (PIQp) in a tracking control algorithm based on sliding mode control. The immediate response of the controller was assessed using a lumped parameter model of the cardiovascular system (CVS) and pump from which could be extracted both Q ̅ est and PIQp. Two different perturbations from the resting state in the presence of left ventricular failure were tested. The first was blood loss requiring a reduction in pump flow to match the reduced output from the right ventricle and to avoid the complication of ventricular suction. The second was exercise, requiring an increase in pump flow. The sliding mode controller induced the required changes in Qp within approximately five heart beats in the blood loss simulation and eight heart beats in the exercise simulation without clinically significant transients or steady-state errors.

  13. Turbulence measurements in an axial rotary blood pump with laser Doppler velocimetry.

    PubMed

    Schüle, Chan Y; Affeld, Klaus; Kossatz, Max; Paschereit, Christian O; Kertzscher, Ulrich

    2017-04-18

    The implantation of rotary blood pumps as ventricular assist devices (VADs) has become a viable therapy for quite a number of patients with end-stage heart failure. However, these rotary blood pumps cause adverse events that are related to blood trauma. It is currently believed that turbulence in the pump flow plays a significant role. But turbulence has not been measured to date because there is no optical access to the flow space in rotary blood pumps because of their opaque casings. This difficulty is overcome with a scaled-up model of the HeartMate II (HM II) rotary blood pump with a transparent acrylic housing. A 2-component laser Doppler velocimetry (LDV) system was used for the measurement of time resolved velocity profiles and velocity spectra upstream and downstream of the rotor blades. Observing similarity laws, the speed and pump head were adjusted to correspond closely to the design point of the original pump - 10,600 rpm speed and 80 mmHg pressure head. A model fluid consisting of a water-glycerol mixture was used. The measured velocity spectra were scalable by the Kolmogorov length and the Kolmogorov length was estimated to be between 14 and 24 µm at original scale, thus being about 1.5 to 3 times the size of a red blood cell. It can be concluded that turbulence is indeed present in the investigated blood pump and that it can be described by Kolmogorov's theory of turbulence. The size of the smallest vortices compares well to the turbulence length scales as found in prosthetic heart valves, for example.

  14. Identifying Physiologically Significant Pumping State Transitions in Implantable Rotary Blood Pumps Used as Left Ventricular Assist Devices: An In-Vivo Study

    DTIC Science & Technology

    2007-11-02

    bearing to support its impeller. The pump is to be used as a left ventricular assist device ( LVAD ). Varying pump speed can control the degree of left...These data indicate that the STI may be a valuable mechanism to in optimal LVAD control. Keywords - Implantable rotary blood pump, pumping states...as a left ventricular assist device ( LVAD ) with both bridge-to-transplant and long-term implantation anticipated. Current commercially used rotary

  15. Experimental study on shear stress distributions in a centrifugal blood pump.

    PubMed

    Mizunuma, Hiroshi; Nakajima, Ryou

    2007-07-01

    Wall shear stress on the pump casing cover was measured using a surface-mounted hot-film sensor. In addition, the shear stress distribution in the pump was qualitatively investigated by means of oil-film visualization. The characteristics of shear stress in the pump are discussed, including the results on the oil-film visualization. The centrifugal blood pump used was a Nikkiso HPM-15 (Nikkiso Co., Ltd, Tokyo, Japan). The hot-film measurement indicated that the shear stress was approximately proportional to the rotating speed, and exceeded 300 Pa when r/R > 0.5 at 3000 rpm. The circumferential average shear stress on the casing cover was of the same order as the characteristic stress sigma obtained from the pump axial torque. These results suggest that the shear stress on the casing cover can be used to evaluate the characteristic shear stress in the pump.

  16. [Determining wall shear stress in artificial blood pumps of heart assist devices].

    PubMed

    Debaene, P; Aguilera, D; Kertzscher, U; Affeld, K

    2002-01-01

    The walls in blood pumps are made of artificial material and thus are thrombogenic to a lesser or larger degree. Also the flow plays a role: a blood flow with no flow separations and stagnation zones is required to avoid the generation of thrombi. A precondition for solving this problem is the assessment of the wall shear rate. However this parameter is difficult to assess because of the deformability of the walls and the pulsation of the flow. Two methods are proposed to estimate the wall shear stress in bloodpumps. The paint erosion method allows a characterisation of the flow near the wall. The second method is a special development of standard Particle Image Velocimetry (PIV). A vector field of the flow close to the wall results. Both methods should permit the assessment of the wall shear stress in bloodpumps.

  17. Improvement of hemolysis in a centrifugal blood pump with hydrodynamic bearings and semi-open impeller.

    PubMed

    Kosaka, Ryo; Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku

    2007-01-01

    We have developed a centrifugal blood pump with hydrodynamic bearings and semi-open impeller, and evaluated the levitation performance test and the hemolysis test. This pump is operated without any complicated control circuit and displacement-sensing module. The casing diameter is 74 mm and the height is 38 mm including flanges for volts. The weight is 251 g and the volume is 159 cm3. By changing the stator relative position against the rotor, the levitation characteristics of the impeller can be adjusted. The diameter of impeller is 36 mm and the height is 25 mm. The impeller is levitated by the thrust bearing of spiral groove type and a radial bearing of herringbone type. The pump performance was evaluated through the levitation performance test and the hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.72 g/100 L to 0.024 g/100 L corresponding to the changes of the groove direction of the hydrodynamic bearing and the expansion of the bearing gap. During these studies, we confirmed that the hemolytic property was improved by balancing the fluid dynamic force and the magnetic force.

  18. Design and parameter estimation of hybrid magnetic bearings for blood pump applications

    NASA Astrophysics Data System (ADS)

    Lim, Tau Meng; Zhang, Dongsheng; Yang, Juanjuan; Cheng, Shanbao; Low, Sze Hsien; Chua, Leok Poh; Wu, Xiaowei

    2009-10-01

    This paper discusses the design and parameter estimation of the dynamics characteristics of a high-speed hybrid magnetic bearings (HMBs) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet (PM) brushless and sensorless DC motor. It is levitated by two HMBs at both ends in five-degree-of-freedom with proportional-integral-derivative (PID) controllers; among which four radial directions are actively controlled and one axial direction is passively controlled. Test results show that the rotor can be stably supported to speeds of 14,000 rpm. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMBs system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air—in both the radial and axial directions. The radial stiffness of the HMBs is compared to the Ansoft's Maxwell 2D/3D finite element magnetostatic results. Experimental estimation showed that the dynamics characteristics of the HMBs system are dominated by the frequency-dependent stiffness coefficients. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamics properties under normal operating conditions with fluid.

  19. Development of a surface micromachined spiral-channel viscous pump

    NASA Astrophysics Data System (ADS)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  20. Numerical study of a centrifugal blood pump with different impeller profiles.

    PubMed

    Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

    2010-01-01

    Computational fluid dynamic simulations of the Kyoto-NTN magnetically suspended centrifugal blood pump with 16 forward-bending blades (16FB), 16 straight blades (16SB), and eight backward-bending blades (8BB) impellers were performed in this study. Commercial CFD software package FLUENT were used as the solver. The purpose of this study is to find out how the impeller blade profiles affect the inner flow and the performance of the centrifugal blood pump. The simulations were carried out with the same impeller rotating speed of 2,000 rpm and pump flow rate of 5 L/min to compare the three pump models. It was found that the 16SB impeller can produce higher pressure head than the 16FB and 8BB impellers under the same impeller rotating speed and pump flow rate. The flow particle tracing was carried out to estimate the blood damage level caused by the three different impeller profiles. It was found that the 16FB and 8BB models have caused the highest and lowest blood damage, respectively. The 16SB is recommended among the three pumps because it can generate the highest pressure head and induce mild blood damage index, although it was higher than that of the 8BB model.

  1. An investigational study of minimum rotational pump speed to avoid retrograde flow in three centrifugal blood pumps in a pediatric extracorporeal life support model.

    PubMed

    Clark, Joseph B; Guan, Yulong; McCoach, Robert; Kunselman, Allen R; Myers, John L; Undar, Akif

    2011-05-01

    During extracorporeal life support with centrifugal blood pumps, retrograde pump flow may occur when the pump revolutions decrease below a critical value determined by the circuit resistance and the characteristics of the pump. We created a laboratory model to evaluate the occurrence of retrograde flow in each of three centrifugal blood pumps: the Rotaflow, the CentriMag, and the Bio-Medicus BP-50. At simulated patient pressures of 60, 80, and 100 mmHg, each pump was evaluated at speeds from 1000 to 2200 rpm and flow rates were measured. Retrograde flow occurred at low revolution speeds in all three centrifugal pumps. The Bio-Medicus pump was the least likely to demonstrate retrograde flow at low speeds, followed by the Rotaflow pump. The CentriMag pump showed the earliest transition to retrograde flow, as well as the highest degree of retrograde flow. At every pump speed evaluated, the Bio-Medicus pump delivered the highest antegrade flow and the CentriMag pump delivered the least.

  2. Evaluation of hydraulic radial forces on the impeller by the volute in a centrifugal rotary blood pump.

    PubMed

    Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-08-01

    In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  3. Power consumption of rotary blood pumps: pulsatile versus constant-speed mode.

    PubMed

    Pirbodaghi, Tohid; Cotter, Chris; Bourque, Kevin

    2014-12-01

    We investigated the power consumption of a HeartMate III rotary blood pump based on in vitro experiments performed in a cardiovascular simulator. To create artificial-pulse mode, we modulated the pump speed by decreasing the mean speed by 2000 rpm for 200 ms and then increasing speed by 4000 rpm (mean speeds plus 2000 rpm) for another 200 ms, creating a square waveform shape. The HeartMate III was connected to a cardiovascular simulator consisting of a hydraulic pump system to simulate left ventricle pumping action, arterial and venous compliance chambers, and an adjustable valve for peripheral resistance to facilitate the desired aortic pressure. The simulator operated based on Suga's elastance model to mimic the Starling response of the heart, thereby reproducing physiological blood flow and pressure conditions. We measured the instantaneous total electrical current and voltage of the pump to evaluate its power consumption. The aim was to answer these fundamental questions: (i) How does pump speed modulation affect pump power consumption? (ii) How does the power consumption vary in relation to external pulsatile flow? The results indicate that speed modulation and external pulsatile flow both moderately increase the power consumption. Increasing the pump speed reduces the impact of external pulsatile flow.

  4. Efficacy evaluation of syringe pump developed for continuous drug infusion

    PubMed Central

    Jung, Bongsu; Seo, Kwang-Suk; Kwon, Suk Jin; Lee, Kiyoung; Hong, Suyong; Seo, Hyounsoon; Kim, Gi-Young; Park, Geun-Mook; Jeong, Juhee

    2016-01-01

    Background In dental intravenous sedation, continuous intravenous infusion of a low-dose drug requires an infusion pump such as a syringe pump. To develop a new syringe pump for clinical use, the functions of the pump must meet certain international standards. Various safety and efficacy tests must be performed on the syringe pump, as stipulated by these standards, and an approval must be received from the approving agency based on such test results. Methods The authors of the present study developed a novel syringe pump and performed efficacy evaluation by testing its infusion speed at 1 and 25 ml/h, and infusion performance testing at 2 and 24 h. Moreover, performance evaluation was conducted by comparing the novel pump to an existing pump with the infusion speed varied from 1 to 5 ml/h. Results In the efficacy testing on the newly developed syringe pump, infusion with the infusion speed initially set to 1 ml/h resulted in infusion speeds of 1.00 and 0.99 ml/h in the 2- and 24-h assessment, respectively. Changing the infusion speed setting to 25 ml/h resulted in an infusion speed of 25.09 and 23.92 ml/h in the 2- and 24-h assessment, respectively. These results show no significant differences when compared with other commercially available pumps. Conclusions The efficacy testing of the newly developed syringe pump showed the accuracy to be within tolerance. Based on these findings, we believe that the newly developed syringe pump is suitable for clinical use. PMID:28879319

  5. Application of Adaptive Starling-Like Controller to Total Artificial Heart Using Dual Rotary Blood Pumps.

    PubMed

    Ng, Boon C; Smith, Peter A; Nestler, Frank; Timms, Daniel; Cohn, William E; Lim, Einly

    2017-03-01

    The successful clinical applicability of rotary left ventricular assist devices (LVADs) has led to research interest in devising a total artificial heart (TAH) using two rotary blood pumps (RBPs). The major challenge when using two separately controlled LVADs for TAH support is the difficulty in maintaining the balance between pulmonary and systemic blood flows. In this study, a starling-like controller (SLC) hybridized with an adaptive mechanism was developed for a dual rotary LVAD TAH. The incorporation of the adaptive mechanism was intended not only to minimize the risk of pulmonary congestion and atrial suction but also to match cardiac demand. A comparative assessment was performed between the proposed adaptive starling-like controller (A-SLC) and a conventional SLC as well as a constant speed controller. The performance of all controllers was evaluated by subjecting them to three simulated scenarios [rest, exercise, head up tilt (HUT)] using a mock circulation loop. The overall results showed that A-SLC was superior in matching pump flow to cardiac demand without causing hemodynamic instabilities. In contrast, improper flow regulation by the SLC resulted in pulmonary congestion during exercise. From resting supine to HUT, overpumping of the RBPs at fixed speed (FS) caused atrial suction, whereas implementation of SLC resulted in insufficient flow. The comparative study signified the potential of the proposed A-SLC for future TAH implementation particularly among outpatients, who are susceptible to variety of clinical scenarios.

  6. Disposable MagLev centrifugal blood pump utilizing a cone-shaped impeller.

    PubMed

    Hijikata, Wataru; Sobajima, Hideo; Shinshi, Tadahiko; Nagamine, Yasuyuki; Wada, Suguru; Takatani, Setsuo; Shimokohbe, Akira

    2010-08-01

    To enhance the durability and reduce the blood trauma of a conventional blood pump with a cone-shaped impeller, a magnetically levitated (MagLev) technology has been applied to the BioPump BPX-80 (Medtronic Biomedicus, Inc., Minneapolis, MN, USA), whose impeller is supported by a mechanical bearing. The MagLev BioPump (MagLev BP), which we have developed, has a cone-shaped impeller, the same as that used in the BPX-80. The suspension and driving system, which is comprised of two degrees of freedom, radial-controlled magnetic bearing, and a simply structured magnetic coupling, eliminates any physical contact between the impeller and the housing. To reduce both oscillation of the impeller and current in the coils, the magnetic bearing system utilizes repetitive and zero-power compensators. In this article, we present the design of the MagLev mechanism, measure the levitational accuracy of the impeller and pressure-flow curves (head-quantity [HQ] characteristics), and describe in vitro experiments designed to measure hemolysis. For the flow-induced hemolysis of the initial design to be reduced, the blood damage index was estimated by using computational fluid dynamics (CFD) analysis. Stable rotation of the impeller in a prototype MagLev BP from 0 to 2750 rpm was obtained, yielding a flow rate of 5 L/min against a head pressure in excess of 250 mm Hg. Because the impeller of the prototype MagLev BP is levitated without contact, the normalized index of hemolysis was 10% less than the equivalent value with the BPX-80. The results of the CFD analysis showed that the shape of the outlet and the width of the fluid clearances have a large effect on blood damage. The prototype MagLev BP satisfied the required HQ characteristics (5 L/min, 250 mm Hg) for extracorporeal circulation support with stable levitation of the impeller and showed an acceptable level of hemolysis. The simulation results of the CFD analysis indicated the possibility of further reducing the blood damage of

  7. Fluid dynamic characterization of operating conditions for continuous flow blood pumps.

    PubMed

    Wu, Z J; Antaki, J F; Burgreen, G W; Butler, K C; Thomas, D C; Griffith, B P

    1999-01-01

    As continuous flow pumps become more prominent as long-term ventricular assist devices, the wide range of conditions under which they must be operated has become evident. Designed to operate at a single, best-efficiency, operating point, continuous flow pumps are required to perform at off-design conditions quite frequently. The present study investigated the internal fluid dynamics within two representative rotary fluid pumps to characterize the quality of the flow field over a full range of operating conditions. A Nimbus/UoP axial flow blood pump and a small centrifugal pump were used as the study models. Full field visualization of flow features in the two pumps was conducted using a laser based fluorescent particle imaging technique. Experiments were performed under steady flow conditions. Flow patterns at inlet and outlet sections were visualized over a series of operating points. Flow features specific to each pump design were observed to exist under all operating conditions. At off-design conditions, an annular region of reverse flow was commonly observed within the inlet of the axial pump, while a small annulus of backflow in the inlet duct and a strong disturbed flow at the outlet tongue were observed for the centrifugal pump. These observations were correlated to a critical nondimensional flow coefficient. The creation of a "map" of flow behavior provides an additional, important criterion for determining favorable operating speed for rotary blood pumps. Many unfavorable flow features may be avoided by maintaining the flow coefficient above a characteristic critical coefficient for a particular pump, whereas the intrinsic deleterious flow features can only be minimized by design improvement. Broadening the operating range by raising the band between the critical flow coefficient and the designed flow coefficient, is also a worthy goal for design improvement.

  8. Outcomes of neonates undergoing extracorporeal membrane oxygenation support using centrifugal versus roller blood pumps.

    PubMed

    Barrett, Cindy S; Jaggers, James J; Cook, E Francis; Graham, Dionne A; Rajagopal, Satish K; Almond, Christopher S; Seeger, John D; Rycus, Peter T; Thiagarajan, Ravi R

    2012-11-01

    Advances in centrifugal blood pump technology have led to increased use of centrifugal pumps in extracorporeal membrane oxygenation (ECMO) circuits. Their efficacy and safety in critically ill neonates remains unknown. Blood cell trauma leading to hemolysis may result in end-organ injury in critically ill neonates receiving centrifugal pump ECMO. We hypothesized that neonates undergoing ECMO support using centrifugal pumps were at increased odds of hemolysis and subsequent end-organ injury. Children 30 days of age or younger who received support with venoarterial ECMO and were reported to the Extracorporeal Life Support Registry during 2007 to 2009 underwent propensity score matching (Greedy matching 1:1) using pre-ECMO support characteristics. A total of 1,592 neonates receiving ECMO (centrifugal pump = 163 and roller pump = 1,492) were identified. Significant differences in demographic, presupport, and cannulation variables were present before matching. One hundred seventy-six neonates who were supported using either centrifugal (n = 88) or roller pumps (n = 88) were matched using propensity scoring. No significant differences in demographic, presupport, or cannulation variables were present after matching. Neonates undergoing support using centrifugal pumps had increased odds of hemolysis (odds ratio [OR], 7.7 [2.8-21.2]), hyperbilirubinemia (OR, 20.8 [2.7-160.4]), hypertension (OR, 3.2 [1.3-8.0]), and acute renal failure (OR, 2.4 [1.1-5.6]). Survival to discharge was not different between pump types. Use of ECMO using centrifugal pumps is associated with increased odds of hemolysis that likely contributes to other end-organ injury. Research into the optimal use of centrifugal pumps and strategies to prevent support-related complications need to be investigated. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  9. Computational fluid dynamics and digital particle image velocimetry study of the flow through an optimized micro-axial blood pump.

    PubMed

    Triep, Michael; Brücker, Christoph; Schröder, Wolfgang; Siess, Thorsten

    2006-05-01

    A detailed knowledge of the flow field in a blood pump is indispensable in order to increase the efficiency of the pump and to reduce the shear-induced hemolysis. Thus, three different impeller designs were developed and tested by means of computational fluid dynamics (CFD) and digital particle image velocimetry (DPIV). The results show a good agreement of CFD and DPIV data. An optimization of the impeller could be achieved by following the concept of turbulent drag reduction for the axisymmetric center body.

  10. Pump

    SciTech Connect

    Johnson, J.W.; Abdul.Hye, A.B.M.

    1983-10-25

    A pump for injecting chemicals into a well employs a pivot arm for synchronous movement with a well pump. The pivot arm causes reciprocation of a plunger within the body of the chemical pump. The plunger, during its upward stroke causes the entry of chemicals from an outside source into the pump body and, during its downward stroke, causes the exiting of the chemicals into the well. (2 claims.

  11. Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    PubMed

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2013-09-01

    A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis.

  12. Computational fluid dynamics-based hydraulic and hemolytic analyses of a novel left ventricular assist blood pump.

    PubMed

    Yang, Xiao-Chen; Zhang, Yan; Gui, Xing-Min; Hu, Sheng-Shou

    2011-10-01

    The advent of various technologies has allowed mechanical blood pumps to become more reliable and versatile in recent decades. In our study group, a novel structure of axial flow blood pump was developed for assisting the left ventricle. The design point of the left ventricular assist blood pump 25 (LAP-25) was chosen at 4 Lpm with 100 mm Hg according to our clinical practice. Computational fluid dynamics was used to design and analyze the performance of the LAP-25. In order to obtain a required hydraulic performance and a satisfactory hemolytic property in the LAP-25 of a smaller size, a novel structure was developed including an integrated shroud impeller, a streamlined impeller hub, and main impeller blades with splitter blades; furthermore, tandem cascades were introduced in designing the diffuser. The results of numerical simulation show the LAP-25 can generate flow rates of 3-5 Lpm at rotational speeds of 8500-10,500 rpm, producing pressure rises of 27.5-148.3 mm Hg with hydraulic efficiency points ranging from 13.4 to 27.5%. Moreover, the fluid field and the hemolytic property of the LAP-25 were estimated, and the mean hemolysis index of the pump was 0.0895% with Heuser's estimated model. In conclusion, the design of the LAP-25 shows an acceptable result.

  13. Fluid dynamic design for low hemolysis in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi; Kuwana, Katsuyuki; Kawaguchi, Yasuo

    2013-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support as a bridge to decision pump. The impeller is levitated using hydrodynamic bearings without any complicated control circuit or displacement sensor. However, the effect of the outer circumferential velocity and the bearing area on the hemolytic property has not been clarified, even if the bearing gap is same size. The purpose of this study is to experimentally evaluate the effect of the outer circumferential velocity and the bearing area in the bearing gaps on the hemolytic property in a hydrodynamically levitated centrifugal blood pump. We prepared three models for testing. These models have the same bearing gap size by adjusting the impeller levitation position. However, the outer circumferential velocity of the impeller and the bearing area in the minimum bearing gaps are different. The outer circumferential velocity of the impeller and the bearing area were assumed to be related to the maximum shear rate and the exposure time. For the evaluation, we conducted an impeller levitation performance test and an in vitro hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.084 g/100 L to 0.040 g/100 L corresponding to a reduction in the outer circumferential velocity and a reduction in the bearing area, even if the minimum bearing gaps were same size. We confirmed that, even if the bearing gap was same size under the stably levitated condition, the outer circumferential velocity and the bearing area should be decreased in order to improve the hemolytic property.

  14. Diode pumped Nd:YAG laser development

    NASA Technical Reports Server (NTRS)

    Reno, C. W.; Herzog, D. G.

    1976-01-01

    A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.

  15. Infusion pumps and red blood cell damage in transfusion therapy: an integrative revision of the academic literature 1

    PubMed Central

    Wilson, Ana Maria Miranda Martins; Peterlini, Maria Angélica Sorgini; Pedreira, Mavilde da Luz Gonçalves

    2016-01-01

    ABSTRACT Objectives: to obtain information from scientific literature concerning infusion pumps used in administering erythrocyte (red blood cells) and to evaluate the implications in the practical use of this equipment by nurses when conducting transfusions. Method: an integrative revision of the following scientific databases: Pubmed/Medline, Scopus, the Virtual Library for Health, SciELO, Web of Science and Cochrane. The following descriptors were used: "infusion pumps", "blood transfusion", "transfused erythrocyte" and "hemolyis". There were no restrictions on the scope of the initial data and it was finalized in December 2014. 17 articles were identified in accordance with the inclusion and exclusion criteria. Results: all of the publications included in the studies were experimental in vitro and covered the use of infusion pumps in transfusion therapy. A summary of the data was presented in a synoptic chart and an analysis of it generated the following categories: cellular damage and the infusion mechanism. Conclusion: infusion pumps can be harmful to erythrocytes based on the infusion mechanism that is used, as the linear peristaltic pump is more likely to cause hemolysis. Cellular damage is related to the plasmatic liberation of markers that largely dominate free hemoglobin and potassium. We reiterate the need for further research and technological investments to guide the development of protocols that promote safe practices and that can contribute to future clinical studies. PMID:27533272

  16. Heat Pump Clothes Dryer Model Development

    SciTech Connect

    Shen, Bo

    2016-01-01

    A heat pump clothes dryer (HPCD) is an innovative appliance that uses a vapor compression system to dry clothes. Air circulates in a closed loop through the drum, so no vent is required. The condenser heats air to evaporate moisture out of the clothes, and the evaporator condenses water out of the air stream. As a result, the HPCD can achieve 50% energy savings compared to a conventional electric resistance dryer. We developed a physics-based, quasi-steady-state HPCD system model with detailed heat exchanger and compressor models. In a novel approach, we applied a heat and mass transfer effectiveness model to simulate the drying process of the clothes load in the drum. The system model is able to simulate the inherently transient HPCD drying process, to size components, and to reveal trends in key variables (e.g. compressor discharge temperature, power consumption, required drying time, etc.) The system model was calibrated using experimental data on a prototype HPCD. In the paper, the modeling method is introduced, and the model predictions are compared with experimental data measured on a prototype HPCD.

  17. Development of a numerical pump testing framework.

    PubMed

    Kaufmann, Tim A S; Gregory, Shaun D; Büsen, Martin R; Tansley, Geoff D; Steinseifer, Ulrich

    2014-09-01

    It has been shown that left ventricular assist devices (LVADs) increase the survival rate in end-stage heart failure patients. However, there is an ongoing demand for an increased quality of life, fewer adverse events, and more physiological devices. These challenges necessitate new approaches during the design process. In this study, computational fluid dynamics (CFD), lumped parameter (LP) modeling, mock circulatory loops (MCLs), and particle image velocimetry (PIV) are combined to develop a numerical Pump Testing Framework (nPTF) capable of analyzing local flow patterns and the systemic response of LVADs. The nPTF was created by connecting a CFD model of the aortic arch, including an LVAD outflow graft to an LP model of the circulatory system. Based on the same geometry, a three-dimensional silicone model was crafted using rapid prototyping and connected to an MCL. PIV studies of this setup were performed to validate the local flow fields (PIV) and the systemic response (MCL) of the nPTF. After validation, different outflow graft positions were compared using the nPTF. Both the numerical and the experimental setup were able to generate physiological responses by adjusting resistances and systemic compliance, with mean aortic pressures of 72.2-132.6 mm Hg for rotational speeds of 2200-3050 rpm. During LVAD support, an average flow to the distal branches (cerebral and subclavian) of 24% was found in the experiments and the nPTF. The flow fields from PIV and CFD were in good agreement. Numerical and experimental tools were combined to develop and validate the nPTF, which can be used to analyze local flow fields and the systemic response of LVADs during the design process. This allows analysis of physiological control parameters at early development stages and may, therefore, help to improve patient outcomes.

  18. Development of small centrifugal pumps for an electric propellant pump system

    NASA Astrophysics Data System (ADS)

    Johnsson, Göran; Bigert, Mikael

    Small centrifugal pumps with low specific speeds have been designed, manufactured and performance tested at Volvo Flygmotor AB under a contract from the European Space Agency (ESA) over the period mid-1985 to mid-1988. The development of the pumps is a part of the work carried out to develop an Electric Propellant Pump System (EPPS) for the storable propellant monomethyl hydrazine (MMH) and nitrogen tetraoxide (NTO). Supporting technology development has been funded by the Swedish Delegation for Space Activities (DFR) and Swedish Space Corporation (SSC) together with Volvo Flygmotor. The main advantages of a typical EPPS communication satellite application are weight and volume reduction of the propellant system compared with a pressure-fed system. Active engine mixture ratio control and improved propellant utilization are also possible. Refuelling in space is another potential application where EPPS can be used. The development work was focused on communication satellite apogee propulsion and used the MBB 3 kN engine as reference. This paper presents the pump design and analyses and the results from the test campaigns of three different pump configurations, carried out with water as test liquid. The head rise, efficiency and suction performance together with other characteristics are also given. The planned next development step is to demonstrate pump performance in the propellants and primarily in NTO. The step is funded by (DFR)/(SSC) together with Volvo Flygmotor.

  19. Hemolysis and heat generation in six different types of centrifugal blood pumps.

    PubMed

    Araki, K; Taenaka, Y; Masuzawa, T; Tatsumi, E; Wakisaka, Y; Watari, M; Nakatani, T; Akagi, H; Baba, Y; Anai, H

    1995-09-01

    What the most causative factor affecting hemolysis is still controversial. To resolve this problem, we investigated the relationship between hemolysis and heat generation in six types of centrifugal blood pumps (Bio-Pump, Delphin, Capiox, Nikkiso, Isoflow, and Toyobo). The analyzed parameters were index of hemolysis in fresh goat blood, pumping performance, and heat generation in a thermally isolated mock circuit. These parameters were analyzed at a flow rate of 5 L/min by changing the pressure head (100 mm Hg and 500 mm Hg). At 500 mm Hg of pressure head, the Bio-Pump needed the highest rotation number and showed the highest hemolytic rate and heat generation. The index of hemolysis is well correlated to heat generation (r2 = 0.721). Heat may originate from the motor by conduction, hydraulic energy loss, and mechanical friction between the shaft and seal. We strongly suspect that hemolysis was caused by a factor such as mechanical friction which generates heat locally.

  20. Development and test of a plastic deep-well pump

    NASA Astrophysics Data System (ADS)

    Zhang, Q. H.; Gao, X. F.; Xu, Y.; Shi, W. D.; Lu, W. G.; Liu, W.

    2013-12-01

    To develop a plastic deep-well pump, three methods are proposed on structural and forming technique. First, the major hydraulic components are constructed by plastics, and the connection component is constructed by steel. Thus the pump structure is more concise and slim, greatly reducing its weight and easing its transportation, installation, and maintenance. Second, the impeller is designed by maximum diameter method. Using same pump casing, the stage head is greatly increased. Third, a sealing is formed by impeller front end face and steel end face, and two slots are designed on the impeller front end face, thus when the two end faces approach, a lubricating pair is formed, leading to an effective sealing. With above methods, the pump's axial length is greatly reduced, and its stage head is larger and more efficient. Especially, the pump's axial force is effectively balanced. To examine the above proposals, a prototype pump is constructed, and its testing results show that the pump efficiency exceeds the national standard by 6%, and the stage head is improved by 41%, meanwhile, its structure is more concise and ease of transportation. Development of this pump would provide useful experiences for further popularity of plastic deep-well pumps.

  1. Influence of radial clearance and rotor motion to hemolysis in a journal bearing of a centrifugal blood pump.

    PubMed

    Kataoka, Hiroyuki; Kimura, Yuichi; Fujita, Hajime; Takatani, Setsuo

    2006-11-01

    Hemolysis due to narrow clearance of noncontact bearings is a critical problem for rotary blood pumps. We developed a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing, and found that the hemolysis in the narrow clearance depends not only on the clearance size, but also on the rotor stability. In this study, we quantified the relation between the hemolysis, radial clearance (c), and rotor stability through the measurement of the rotor motion and hemolysis. As a result, it was confirmed that the rotor of the current pump is stabilized within the oscillation of 20 microm in blood, and the hemolysis decreases with increase in the c, which is the opposite in the unstable rotor motion with the previous pump. In order to theoretically discuss this hemolysis tendency, we implemented hemolysis estimation in the c according to hydrodynamics and hemodynamics. This estimation can represent the measured hemolysis tendency, and revealed that the flow rate has large influence on the hemolysis in the c.

  2. Evaluation of cardiac function during left ventricular assist by a centrifugal blood pump.

    PubMed

    Kikugawa, D

    2000-08-01

    In this study, the effects on varying cardiac function during a left ventricular (LV) bypass from the apex to the descending aorta using a centrifugal blood pump were evaluated by analyzing the left ventricular pressure and the motor current of the centrifugal pump in a mock circulatory loop. Failing heart models (preload 15 mm Hg, afterload 40 mm Hg) and normal heart models (preload 5 mm Hg, afterload 100 mm Hg) were simulated by adjusting the contractility of the latex rubber left ventricle. In Study 1, the bypass flow rate, left ventricular pressure, aortic pressure, and motor current levels were measured in each model as the centrifugal pump rpm were increased from 1,000 to 1,500 to 2,000. In Study 2, the pump rpm were fixed at 1,300, 1,500, and 1,700, and at each rpm, the left ventricular peak pressure was increased from 40 to 140 mm Hg by steps of 20 mm Hg. The same measurements as in Study 1 were performed. In Study 1, the bypass flow rate and mean aortic pressure both increased with the increase in pump rpm while the mean left ventricular pressure decreased. In Study 2, a fairly good correlation between the left ventricular pressure and the motor current of the centrifugal pump was obtained. These results suggest that cardiac function as indicated by left ventricular pressure may be estimated from a motor current analysis of the centrifugal blood pump during left heart bypass.

  3. Real-Time Observation of Thrombus Growth Process in an Impeller of a Hydrodynamically Levitated Centrifugal Blood Pump by Near-Infrared Hyperspectral Imaging.

    PubMed

    Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Fujiwara, Tatsuki; Nishida, Masahiro; Maruyama, Osamu

    2015-08-01

    Understanding the thrombus formation in cardiovascular devices such as rotary blood pumps is the most important issue in developing more hemocompatible devices. The objective of this study was to develop a hyperspectral imaging (HSI) method to visualize the thrombus growth process within a rotary blood pump and investigate the optical properties of the thrombus. An in vitro thrombogenic test was conducted using fresh porcine blood and a specially designed hydrodynamically levitated centrifugal blood pump with a transparent bottom. The pump rotating at 3000 rpm circulated the blood at 1.0 L/min. The bottom surface of the pump was illuminated with white light pulsed at the same frequency as the pump rotation, and the backward-scattered light was imaged using the HSI system. Using stroboscopic HSI and an image construction algorithm, dynamic spectral imaging at wavelengths ranging from 608 to 752 nm within the rotating pump was achieved. After completing the experiment, we collected the red thrombus formed in the pump impeller and quantified the thrombus hemoglobin concentration (Hbthrombus ). The spectrum changed around the center of the impeller, and the area of change expanded toward the impeller flow path. The shape corresponded approximately to the shape of the thrombus. The spectrum change indicated that the light scattering derived from red blood cells decreased. The Hbthrombus was 4.7 ± 1.3 g/dL versus a total hemoglobin of 13 ± 0.87 g/dL. The study revealed that Hbthrombus was reduced by the surrounding blood flow.

  4. A compact centrifugal blood pump for extracorporeal circulation: design and performance.

    PubMed

    Tanaka, S; Yamamoto, S; Yamakoshi, K; Kamiya, A

    1987-08-01

    A new compact centrifugal blood pump driven by a miniature DC servomotor has been designed for use for short-term extra corporeal and cardiac-assisted circulation. The impeller of the pump was connected directly to the motor by using a simple-gear coupling. The shaft for the impeller was sealed from blood by both a V-ring and a seal bearing. Either pulsatile or nonpusatile flow was produced by controlling the current supply to the motor. The pump characteristics and the degree of hemolysis were evaluated with regard to the configuration of the impeller with a 38-mm outer diameter in vitro tests; the impeller having the blade angles at the inlet of 20 deg and at the outlet of 50 deg was the most appropriate as a blood pump. The performance in an operation, hemolysis and thrombus formation in the pump were assessed by a left ventricular bypass experiment in dogs. It was suggested by this study that this prototype pump appears promising for use not only in animal experiments but also in clinical application.

  5. Validation of an axial flow blood pump: computational fluid dynamics results using particle image velocimetry.

    PubMed

    Su, Boyang; Chua, Leok Poh; Wang, Xikun

    2012-04-01

    A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  6. Pediatric ECMO outcomes: comparison of centrifugal versus roller blood pumps using propensity score matching.

    PubMed

    Barrett, Cindy S; Jaggers, James J; Cook, E Francis; Graham, Dionne A; Yarlagadda, Vasmi V; Teele, Sarah A; Almond, Christopher S; Bratton, Susan L; Seeger, John D; Dalton, Heidi J; Rycus, Peter T; Laussen, Peter C; Thiagarajan, Ravi R

    2013-01-01

    Centrifugal blood pumps are being increasingly utilized in children supported with extracorporeal membrane oxygenation (ECMO). Our aim was to determine if survival and ECMO-related morbidities in children supported with venoarterial (VA) ECMO differed by blood pump type.Children aged less than 18 years who underwent VA ECMO support from 2007 to 2009 and reported to the Extracorporeal Life Support Organization registry were propensity score matched (Greedy 1:1 matching) using pre-ECMO characteristics.A total of 2,656 (centrifugal = 2,231, roller = 425) patients were identified and 548 patients (274 per pump type) were included in the propensity score-matched cohort. Children supported with centrifugal pumps had increased odds of hemolysis (odds ratio [OR], 4.03 95% confidence interval [CI], 2.37-6.87), hyperbilirubinemia (OR, 5.48; 95% CI, 2.62-11.49), need for inotropic support during ECMO (OR, 1.54; 95% CI, 1.09-2.17), metabolic alkalosis (blood pH > 7.6) during ECMO (OR, 3.13; 95% CI, 1.49-6.54), and acute renal failure (OR, 1.61; 95% CI, 1.10-2.39). Survival to hospital discharge did not differ by pump type.In a propensity score-matched cohort of pediatric ECMO patients, children supported with centrifugal pumps had increased odds of ECMO-related complications. There was no difference in survival between groups.

  7. Blood warming, pump heating and haemolysis in low-flow extracorporeal life support; an in vitro study using freshly donated human blood.

    PubMed

    Kusters, R W J; Simons, A P; Lancé, M D; Ganushchak, Y M; Bekers, O; Weerwind, P W

    2017-01-01

    Low-flow extracorporeal life support can be used for cardiopulmonary support of paediatric and neonatal patients and is also emerging as a therapy for patients suffering from exacerbation of chronic obstructive pulmonary disease. However, pump heating and haemolysis have proven to negatively affect the system and outcome. This in vitro study aimed at gaining insight into blood warming, pump heating and haemolysis related to the performance of a new low-flow centrifugal pump. Pump performance in the 400-1,500 ml/min flow range was modulated using small-sized dual-lumen catheters and freshly donated human blood. Measurements included plasma free haemoglobin, blood temperature, pump speed, pump pressure, blood flow and thermographic imaging. Blood warming (ΔTmax=0.5°C) had no relationship with pump performance or haemolysis (R(2)max=0.05). Pump performance-related parameters revealed no relevant relationships with haemolysis (R(2)max=0.36). Thermography showed no relevant heat zones in the pump (Tmax=36°C). Concerning blood warming, pump heating and haemolysis, we deem the centrifugal pump applicable for low-flow extracorporeal circulation.

  8. Feasibility of Pump Speed Modulation for Restoring Vascular Pulsatility with Rotary Blood Pumps.

    PubMed

    Ising, Mickey S; Sobieski, Michael A; Slaughter, Mark S; Koenig, Steven C; Giridharan, Guruprasad A

    2015-01-01

    Continuous flow (CF) left ventricular assist devices (LVAD) diminish vascular pressure pulsatility, which may be associated with clinically reported adverse events including gastrointestinal bleeding, aortic valve insufficiency, and hemorrhagic stroke. Three candidate CF LVAD pump speed modulation algorithms designed to augment aortic pulsatility were evaluated in mock flow loop and ischemic heart failure (IHF) bovine models by quantifying hemodynamic performance as a function of mean pump speed, modulation amplitude, and timing. Asynchronous and synchronous copulsation (high revolutions per minute [RPM] during systole, low RPM during diastole) and counterpulsation (low RPM during systole, high RPM during diastole) algorithms were tested for defined modulation amplitudes (±300, ±500, ±800, and ±1,100 RPM) and frequencies (18.75, 37.5, and 60 cycles/minute) at low (2,900 RPM) and high (3,200 RPM) mean LVAD speeds. In the mock flow loop model, asynchronous, synchronous copulsation, and synchronous counterpulsation algorithms each increased pulse pressure (ΔP = 931%, 210%, and 98% and reduced left ventricular external work (LVEW = 20%, 22%, 16%). Similar improvements in vascular pulsatility (1,142%) and LVEW (40%) were observed in the IHF bovine model. Asynchronous modulation produces the largest vascular pulsatility with the advantage of not requiring sensor(s) for timing pump speed modulation, facilitating potential clinical implementation.

  9. Onset of Buccal Pumping in Catshark Embryos: How Breathing Develops in the Egg Capsule

    PubMed Central

    Tomita, Taketeru; Nakamura, Masaru; Sato, Keiichi; Takaoka, Hiroko; Toda, Minoru; Kawauchi, Junro; Nakaya, Kazuhiro

    2014-01-01

    Respiration in fishes involves buccal pumping, which is characterized by the generation of nearly continuous water flow over the gills because of the rhythmic expansion/compression of the pharyngeal cavity. This mechanism is achieved by the functions of the vascular, skeletal, and muscular systems. However, the process by which the embryo establishes the mechanism remains a mystery. Morphological and kinematical observations on captive cloudy catsharks, Scyliorhinus torazame, have suggested that the embryo starts buccal pumping just before the respiratory slits open on the egg capsule. During the pre-opening period, the embryo acquires oxygen mainly via the external gill filaments. After slit opening, respiration of the embryo involves buccal pumping to pass water over the “internal gills.” The onset of buccal pumping accompanies four morphological changes: (1) regression of the external gill filaments, (2) development of blood vessels within the “internal gills,” (3) completion of the development of hyoid skeletal and muscular elements, and (4) development of the oral valve. A previous study showed that buccal pumping allows the embryo to actively regulate oxygen intake by changing the pumping frequency. Thus, establishment of buccal pumping in the egg capsule is probably important for embryo survival in the unstable oxygen environment of the egg capsule after slit opening. PMID:25329313

  10. Onset of buccal pumping in catshark embryos: how breathing develops in the egg capsule.

    PubMed

    Tomita, Taketeru; Nakamura, Masaru; Sato, Keiichi; Takaoka, Hiroko; Toda, Minoru; Kawauchi, Junro; Nakaya, Kazuhiro

    2014-01-01

    Respiration in fishes involves buccal pumping, which is characterized by the generation of nearly continuous water flow over the gills because of the rhythmic expansion/compression of the pharyngeal cavity. This mechanism is achieved by the functions of the vascular, skeletal, and muscular systems. However, the process by which the embryo establishes the mechanism remains a mystery. Morphological and kinematical observations on captive cloudy catsharks, Scyliorhinus torazame, have suggested that the embryo starts buccal pumping just before the respiratory slits open on the egg capsule. During the pre-opening period, the embryo acquires oxygen mainly via the external gill filaments. After slit opening, respiration of the embryo involves buccal pumping to pass water over the "internal gills." The onset of buccal pumping accompanies four morphological changes: (1) regression of the external gill filaments, (2) development of blood vessels within the "internal gills," (3) completion of the development of hyoid skeletal and muscular elements, and (4) development of the oral valve. A previous study showed that buccal pumping allows the embryo to actively regulate oxygen intake by changing the pumping frequency. Thus, establishment of buccal pumping in the egg capsule is probably important for embryo survival in the unstable oxygen environment of the egg capsule after slit opening.

  11. Development of the sonic pump levitator

    NASA Technical Reports Server (NTRS)

    Dunn, S. A.

    1985-01-01

    The process and mechanism involved in producing glass microballoons (GMBs) of acceptable quality for laser triggered inertial fusion through use of glass jet levitation and manipulation are considered. The gas jet levitation device, called sonic pumps, provides positioning by timely and appropriate application of gas mementum from one or more of six sonic pumps which are arranged orthogonally in opposed pairs about the levitation region and are activated by an electrooptical, computer controlled, feedback system. The levitation device was fabricated and its associated control systems were assembled into a package and tested in reduced gravity flight regime of the NASA KC-135 aircraft.

  12. FIELD TRIALS OF NEWLY DEVELOPED POSITIVE DISPLACEMENT SUBMERSIBLE PUMP

    SciTech Connect

    Rob Beard; Leland Traylor

    2002-12-01

    The purpose of this grant was to evaluate under real world conditions the performance of a new type of downhole pump, the hydraulically driven submersible diaphragm pump. This pump is supplied by Pumping Solutions Incorporated, Albuquerque NM. The original scope of the project was to install 10 submersible pumps, and compare that to 10 similar installations of rod pumps. As an operator, the system as tested was not ready for prime time. The PSI group did improve the product and offered excellent service. The latest design appears to be much better, but more test data is needed to show short run life is not a problem. This product should continue to be developed; the testing did not uncover any fundamental problems that would preclude it's widespread use. On the positive side, the pump was easy to run, was more power efficient then a rod pump, and is the only submersible that could handle the large quantities of solids typical of CBM production. The product shows much promise for the future, and with continued design and testing, this type of submersible pump has the potential to become the standard of the industry.

  13. Noninvasive miniaturized mass-flow meter using a curved cannula for implantable axial flow blood pump.

    PubMed

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-01-01

    Blood flow should be measured to monitor conditions of patients with implantable artificial hearts continuously and noninvasively. We have developed a noninvasive miniaturized mass-flow meter using a curved cannula for an axial flow blood pump. The mass-flow meter utilized centrifugal force generated by the mass-flow rate in the curved cannula. Two strain gauges served as sensors. Based on the numerical analysis, the first gauge, attached to the curved area, measured static pressure and centrifugal force, and the second, attached to the straight area, measured static pressure for static pressure compensation. The mass-flow rate was determined by the differences in output from the two gauges. To compensate for the inertia force under the pulsatile flow, a 0.75-Hz low-pass filter was added to the electrical circuit. In the evaluation tests, numerical analysis and an actual measurement test using bovine blood were performed to evaluate the measurement performances. As a result, in the numerical analysis, the relationship between the differential pressure caused by centrifugal force and the flow rate was verified. In the actual measurement test, measurement error was less than ± 0.5 L/min, and the time delay was 0.12 s. We confirmed that the developed mass-flow meter was able to measure mass-flow rate continuously and noninvasively.

  14. Modeling study of the failing heart and its interaction with an implantable rotary blood pump.

    PubMed

    Ramachandran, Deepa P; Luo, Chuan; Ma, Tony S; Clark, John W

    2011-01-01

    The effectiveness of clinical diagnosis and treatment of heart failure is a direct function of clinical signs that can be measured in a patient within cost and safety constraints. Large-scale mathematical modeling can be a key tool in revealing important, measurable clinical signs of heart failure, furthering medical understanding and development of treatment. In the first part of this study we have created two models of left heart failure--diastolic and systolic, using our human cardiovascular-respiratory system (H-CRS) model, and we present a comparison of the two types with emphasis on novel and differentiating clinical signs, such as tricuspid flow and septal motion. In the event of compromised left ventricular performance, mechanical left ventricular assist devices (LVAD) are often implanted to augment or completely replace the pumping action of the left ventricle (LV). One such type is the implantable rotary blood pump (iRBP). Several design issues related to the iRBP are difficult to study experimentally due to procedure complexity and limitations in animal models of heart failure [2]. Therefore, modeling has become a key tool in iRBP development. In the second part of this study, we have introduced an iRBP model based on [1]-[2] in the systolic failing heart to study the interactions. We consider optimal motor settings for different levels of LV assistance, the effects of the iRBP on the right heart, septum, and pulmonary circulation. Our model results align with those reported in [1]-[2]. Improvement in cardiac output, pulmonary congestion, and heart work are seen with the iRBP. We observe lowered septal assistance to RV and LV ejection with increasing pump speeds, elevating right ventricular (RV) work, reducing LVET, and causing ventricular mechanical dyssynchrony in ejection. These results suggest right heart compromise via the septum's reduced role with the introduction of an iRBP. This work emphasizes the critical role of modeling in heart failure and

  15. The effect of surface roughness on activation of the coagulation system and platelet adhesion in rotary blood pumps.

    PubMed

    Linneweber, Jörg; Dohmen, Pascal Maria; Kertzscher, Ulrich; Kerzscher, Ullrich; Affeld, Klaus; Nosé, Yukihiko; Konertz, Wolfgang

    2007-05-01

    The surface roughness of left ventricular assist devices (LVADs) is important for the biocompatibility of blood pumps. However, little is known about the effect of surface roughness on the antithrombogenicity of the device. The present study investigated the effect of surface roughness on the activation of the coagulation system and platelet adhesion in an impeller-type blood pump. Three identical Baylor Gyro 710 centrifugal blood pumps (Baylor College of Medicine, Houston, TX, USA) were manufactured with impeller surface roughness of 0.05, 0.2, and 0.4 microm, respectively, as determined by a stylus profilometer and by scanning electron microscopy. Whole blood was anticoagulated (1-IU heparin/mL, ACT 250 s) and circulated for 60 min in an artificial circulatory system, simulating LVAD perfusion (5-L/min flow against 100 mm Hg). Enzyme-linked immunosorbent assays were developed to quantify fibrinogen- and von Willebrand factor (vWf) adsorption as well as platelet adhesion directly on the impellers of the pumps. Levels of prothrombin fragment F1.2 and thrombin-antithrombin (TAT) complex were measured in order to quantify activation of coagulation. Compared with the 0.05-microm surface, platelet adhesion was 40 and 76% higher on the 0.2- and 0.4-microm surface, respectively (P < 0.01). The evaluation of adsorbed fibrinogen and vWf showed significant higher protein antigen levels on the rougher surfaces (P < 0.01). Furthermore, nonpulsatile perfusion activated the coagulation system. By contrast, the surface roughness had no significant influence on plasma prothrombin F1.2 fragment- and TAT concentrations. Antithrombogenicity was significantly reduced in pumps with inferior metal-finishing quality.

  16. Development of an atraumatic small centrifugal pump for second-generation cardiopulmonary bypass.

    PubMed

    Jikuya, T; Sasaki, T; Aizawa, T; Shiono, M; Glueck, J A; Smith, C P; Feldman, L; Sakuma, I; Sekela, M E; Noda, T

    1992-12-01

    A small and light direct-drive centrifugal pump has been developed for cardiopulmonary bypass. In the development process, blood compatibility studies including a hemolysis study, an in vitro fluid dynamic performance study, and in vivo durability and feasibility studies were performed. The centrifugal pump with a 50 mm diameter impeller resulted in almost the same index of hemolysis value as did a Bio-Medicus centrifugal pump. Heat dissipation from the motor was prevented by using a flexible drive cable. Forty-eight-hour sealing durability around the driving axis was accomplished by using a fluoro-rubber V-ring that connected to the hard chrome-plated stainless steel. In vitro and in vivo performances of the pump were satisfactory. Thrombus formation behind the impeller was prevented by using a holed impeller that generated blood flow from the back to the surface of the impeller. Elimination of air during priming procedures was also easier with this modification. This centrifugal pump has one-quarter of the priming volume, size, and weight of magnetically coupled centrifugal pump systems.

  17. [Development of blood cell measurement].

    PubMed

    Okada, T

    2000-10-01

    Automated blood cell analyzers used in hematology laboratories are required to measure many specimens rapidly and efficiency has been realized through increasing the measurement parameters and throughput volume in one instrument. In the period of 1950's through the early part of 1960's, only red blood cells and white blood cells could be counted. In 1965, Technicon Corporation developed an instrument which can measure the number of blood cells, hemoglobin, hematocrit and calculate corpuscular constants simultaneously. Thereafter, the methodologies for simultaneous platelet measurement and precise determination of blood cell distribution have been developed. Then, the development of new reagents has achieved three part differentials in the distribution of white blood cells. Thanks to this development, microscopic white blood cell differentials has been replaced by blood cell analyzers in screening tests. Though blood cell analyzers may be further improved by expanding of the number of parameters available for simultaneous measurements, meeting social needs in the new era will not be possible without the creation and realization of new concepts employing new technologies such as IT (Information Technology).

  18. Hemolytic performance of a MagLev disposable rotary blood pump (MedTech Dispo): effects of MagLev gap clearance and surface roughness.

    PubMed

    Hoshi, Hideo; Asama, Junichi; Hijikata, Wataru; Hara, Chikara; Shinshi, Tadahiko; Yasuda, Toshitaka; Ohuchi, Katsuhiro; Shimokohbe, Akira; Takatani, Setsuo

    2006-12-01

    Mechanical shaft seal bearing incorporated in the centrifugal blood pumps contributes to hemolysis and thrombus formation. In addition, the problem of durability and corrosion of mechanical shaft seal bearing has been recently reported from the safety point of view. To amend the shortcomings of the blood-immersed mechanical bearings, a magnetic levitated centrifugal rotary blood pump (MedTech Dispo Model 1; Tokyo Medical and Dental University, Tokyo, Japan) has been developed for extracorporeal disposable application. In this study, the hemolytic performance of the MedTech Dispo Model 1 centrifugal blood pump system was evaluated, with special focus on the narrow blood path clearance at the magnetic bearing between rotor and stator, and on the pump housing surface roughness. A pump flow of 5 L/min against the head pressure of 100 mm Hg for 4 h was included in the hemolytic test conditions. Anticoagulated fresh porcine blood was used as a working fluid. The clearance of blood path at the magnetic bearing was in the range of 100-250 micro m. Pump housing surface roughness was controlled to be around Ra = 0.1-1.5 micro m. The lowest hemolytic results were obtained at the clearance of 250 micro m and with the polished surface (Ra = 0.1 micro m) yielding the normalized index of hemolysis (NIH) of less than 0.001 g/100 L, which was 1/5 of the Biopump BP-80 (Medtronic Inc., Minneapolis, MN, USA, and 1/4 of the BPX-80. In spite of rough surface and narrow blood path, NIH levels were less than clinically acceptable level of 0.005 g/100 L. The noncontact, levitated impeller system is useful to improve pump performance in blood environment.

  19. Generic safety requirements for developing safe insulin pump software.

    PubMed

    Zhang, Yi; Jetley, Raoul; Jones, Paul L; Ray, Arnab

    2011-11-01

    The authors previously introduced a highly abstract generic insulin infusion pump (GIIP) model that identified common features and hazards shared by most insulin pumps on the market. The aim of this article is to extend our previous work on the GIIP model by articulating safety requirements that address the identified GIIP hazards. These safety requirements can be validated by manufacturers, and may ultimately serve as a safety reference for insulin pump software. Together, these two publications can serve as a basis for discussing insulin pump safety in the diabetes community. In our previous work, we established a generic insulin pump architecture that abstracts functions common to many insulin pumps currently on the market and near-future pump designs. We then carried out a preliminary hazard analysis based on this architecture that included consultations with many domain experts. Further consultation with domain experts resulted in the safety requirements used in the modeling work presented in this article. Generic safety requirements for the GIIP model are presented, as appropriate, in parameterized format to accommodate clinical practices or specific insulin pump criteria important to safe device performance. We believe that there is considerable value in having the diabetes, academic, and manufacturing communities consider and discuss these generic safety requirements. We hope that the communities will extend and revise them, make them more representative and comprehensive, experiment with them, and use them as a means for assessing the safety of insulin pump software designs. One potential use of these requirements is to integrate them into model-based engineering (MBE) software development methods. We believe, based on our experiences, that implementing safety requirements using MBE methods holds promise in reducing design/implementation flaws in insulin pump development and evolutionary processes, therefore improving overall safety of insulin pump

  20. Generic Safety Requirements for Developing Safe Insulin Pump Software

    PubMed Central

    Zhang, Yi; Jetley, Raoul; Jones, Paul L; Ray, Arnab

    2011-01-01

    Background The authors previously introduced a highly abstract generic insulin infusion pump (GIIP) model that identified common features and hazards shared by most insulin pumps on the market. The aim of this article is to extend our previous work on the GIIP model by articulating safety requirements that address the identified GIIP hazards. These safety requirements can be validated by manufacturers, and may ultimately serve as a safety reference for insulin pump software. Together, these two publications can serve as a basis for discussing insulin pump safety in the diabetes community. Methods In our previous work, we established a generic insulin pump architecture that abstracts functions common to many insulin pumps currently on the market and near-future pump designs. We then carried out a preliminary hazard analysis based on this architecture that included consultations with many domain experts. Further consultation with domain experts resulted in the safety requirements used in the modeling work presented in this article. Results Generic safety requirements for the GIIP model are presented, as appropriate, in parameterized format to accommodate clinical practices or specific insulin pump criteria important to safe device performance. Conclusions We believe that there is considerable value in having the diabetes, academic, and manufacturing communities consider and discuss these generic safety requirements. We hope that the communities will extend and revise them, make them more representative and comprehensive, experiment with them, and use them as a means for assessing the safety of insulin pump software designs. One potential use of these requirements is to integrate them into model-based engineering (MBE) software development methods. We believe, based on our experiences, that implementing safety requirements using MBE methods holds promise in reducing design/implementation flaws in insulin pump development and evolutionary processes, therefore improving

  1. The pivot wash in two impeller modes for the Baylor/Miwatec centrifugal blood pump.

    PubMed

    Yamane, Takashi; Kodama, Takayuki; Nishida, Masahiro; Maruyama, Osamu; Yamamoto, Yoshiro; Shinohara, Toshiyuki; Motomura, Tadashi; Nosé, Yukihiko

    2006-01-01

    A centrifugal blood pump with a double pivot impeller and an eccentric inlet port is being developed as an implantable artificial heart by the Baylor College of Medicine and Miwatec Co. Ltd. Flow visualization measurements were conducted to compare the flow around the pivot for two impeller operational modes: the top and the bottom contact modes. In the top contact mode, one-way flow in the pivot gap due to the eccentric vortex was observed, and sufficient wall shear rate to prevent thrombus formation was attained around the bottom pivot for over 1,400 rpm. Computational fluid dynamic analyses confirmed that the causes of the eccentric vortex were the inlet eccentricity and the pressure imbalance in the volute.

  2. Numerical study of a bio-centrifugal blood pump with straight impeller blade profiles.

    PubMed

    Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

    2010-02-01

    Computational fluid dynamic simulations of the flow in the Kyoto-NTN (Kyoto University, Kyoto, Japan) magnetically suspended centrifugal blood pump with a 16-straight-bladed impeller were performed in the present study. The flow in the pump was assumed as unsteady and turbulent, and blood was treated as a Newtonian fluid. At the impeller rotating speed of 2000 rpm and flow rate of 5 L/min, the pump produces a pressure head of 113.5 mm Hg according to the simulation. It was found that the double volute of the pump has caused symmetrical pressure distribution in the volute passages and subsequently caused symmetrical flow patterns in the blade channels. Due to the tangentially increasing pressure in the volute passages, the flow through the blade channels initially increases at the low-pressure region and then decreases due to the increased pressure. The reverse flow and vortices have been identified in the impeller blade channels. The high shear stress of the flow in the pump mainly occurred at the inlet and outlet of the blade channels, the beginning of the volute passages and the regions around the tips of the cutwater and splitter plate. Higher shear stress is obtained when the tips of the cutwater and splitter plate are located at the impeller blade trailing edges than when they are located at the middle of the impeller blade channel. It was found that the blood damage index assessed based on the blood corpuscle path tracing of the present pump was about 0.94%, which has the same order of magnitude as those of the clinical centrifugal pumps reported in the literature.

  3. WITHDRAWN: Modeling of Transient Phenomena in an Axial Flow Blood Pump

    NASA Astrophysics Data System (ADS)

    Wood, Houston

    2005-11-01

    A fully implantable axial flow Ventricular Assist Device (VAD) has been developed with a magnetically suspended impeller (LEV-VAD). The LEV-VAD's flow path design provides a single pass blood path with minimal turbulence. The pump design included the extensive use of CFD modeling and experimental validation under steady-state flow conditions. This CFD study explores transient flow phenomena in the pump simulating in vivo flow conditions. The LEV-VAD operates under transient conditions due to the pulsatile inlet flow rate induced by the patient's native heart and the spinning of the impeller. This study considered: (1) Time varying boundary conditions (TVBC); (2) Stationary-rotating blades interaction or transient sliding interfaces (TSI). The LEV-VAD performance and pressure-flow correlations were investigated under transient flow conditions. The fluid forces acting on the impeller were calculated to facilitate the suspension system and motor design. The transient simulations illustrate the LEV-VAD's response to dynamic flow conditions and demonstrated the ability to deliver flows from 2 to 10 LPM at rotational speeds varying from 5,000 to 8,000 RPM for physiological pressures corresponding to adult CHF patients.

  4. Mathematical model development and simulation of heat pump fruit dryer

    SciTech Connect

    Achariyaviriya, S.; Soponronnarit, S.; Terdyothin, A.

    2000-01-01

    A mathematical model of a heat pump fruit dryer was developed to study the performance of heat pump dryers. Using the moisture content of papaya glace drying, the refrigerant temperature at the evaporator and condenser and the performance, was verified. It was found that the simulated results using closed loop heat pump dryer were close to the experimental results. The criteria for evaluating the performance were specific moisture extraction rate and drying rate. The results showed that ambient conditions affected significantly on the performance of the open loop dryer and the partially closed loop dryer. Also, the fraction of evaporator bypass air affected markedly the performance of all heat pump dryers. In addition, it was found that specific air flow rate and drying air temperature affected significantly the performance of all heat pump dryers.

  5. Implantation of the VentrAssist Implantable Rotary Blood Pump in sheep.

    PubMed

    James, Natalie L; van der Meer, Anita L; Edwards, Glenn A; Snelling, Samuel R; Begg, John D; Esmore, Donald S; Woodard, John C

    2003-01-01

    The VentrAssist Implantable Rotary Blood Pump (IRBP) is a hydrodynamically suspended, electromagnetically driven, centrifugal blood pump that provides continuous flow of up to 10 L/min at 3,000 rpm. In vivo studies in sheep were conducted to assess system design and performance. Surgery involved thoracotomy with subdiaphragmatic pump placement. Cannulae were transdiaphragmatic, with inflow in the left ventricular apex and outflow anastomosed to the descending aorta. Animals had no anticoagulation or antiplatelet therapy after surgery and no prophylactic antibiotics after recovery. Twelve sheep were supported for 622 pump days. Estimated pump flow ranged from 1 to 5.5 L/min at 1,800 to 2,000 rpm using 2.5 to 4.5 W. There was no clinical evidence of hemolysis or cardiovascular, renal, or hepatic dysfunction. Adverse outcomes included kinking/disconnection of the outflow cannula caused by the graft bend relief (n = 4), which was addressed through cannula redesign. Pump electrical malfunction (n = 4), caused by a silicone potting compound, was corrected using a neutral curing potting material. Surgical/husbandry issues (n = 2) also were addressed. The VentrAssist IRBP provides high flow at low rotational speed and power consumption. Further trials are in progress in advance of in vivo studies of the safety and efficacy of the final system.

  6. Solar-pumped gas laser development

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.

    1981-01-01

    The direct conversion of solar radiation into an inverted population for extraction in an optical cavity holds promise as a relatively simple system design. Broad-band photoabsorption in the visible or near-UV range is required to excite large volumes of gas and to ensure good solar absorption efficiency. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than approximately 10 A. The system should show chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. A search of electronic-vibrational transitions in diatomic molecules satisfying these conditions is now in progress. A photodissociation-pumped atomic iodine laser is now being tested under solar pumping conditions. Photodissociation studies for thallium spin-flip metastable formation will begin in the near future.

  7. Solar-pumped gas laser development

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.

    1980-01-01

    A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

  8. Transient Stress- and Strain-Based Hemolysis Estimation in a Simplified Blood Pump

    PubMed Central

    Pauli, L.; Nam, J.; Pasquali, M.; Behr, M.

    2014-01-01

    SUMMARY We compare two approaches to numerical estimation of mechanical hemolysis in a simplified blood pump model. The stress-based model relies on the instantaneous shear stress in the blood flow, whereas the strain-based model uses an additional tensor equation to relate distortion of red blood cells to a shear stress measure. We use the newly proposed least-squares finite element method (LSFEM) to prevent negative concentration fields and show a stable and volume preserving LSFEM for the tensor equation. Application of both models to a simplified centrifugal blood pump at three different operating conditions show that the stress-based model overestimates the rate of hemolysis. The strain-based model is found to deliver lower hemolysis rates since it incorporates a more detailed description of biophysical phenomena into the simulation process. PMID:23922311

  9. Development of a Bearingless Ammonia Pump for Spacecraft Thermal Control

    DTIC Science & Technology

    2008-01-01

    2008 2. REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE Development of a Bearingless Ammonia Pump for Spacecraft ...REVIEW 245 SPACE RESEARCH AND SATELLITE TECHNOLOGY Development of a Bearingless Ammonia Pump for Spacecraft Thermal Control R.W. Baldauff, T. Kawecki, W...Purdy, and T.T. Hoang Spacecraft Engineering Department Advanced Thermal Control Technology for Navy’s Future Needs: The potential increase in

  10. Numerical simulation and experimental research on passive hydrodynamic bearing in a blood pump

    NASA Astrophysics Data System (ADS)

    Han, Qing; Ruan, Xiaodong; Chen, Wenyu; Fu, Xin

    2013-09-01

    The current research of hydrodynamic bearing in blood pump mainly focuses on the bearing structure design. Compared with the typical plane slider bearing and Rayleigh step bearing, spiral groove bearing has excellent performance in load-carrying capacity. However, the load-carrying capacity would decrease significantly with increasing flow rate in conventional designs. In this paper, the special treatment is made to the upper spiral groove bearing to make sure that both the circulatory flowing and load-carrying capacity are high. Three-dimensional computational fluid dynamics(CFD) models in the space between rotor and shaft are developed by using FLUENT software. Effects of groove number, film height and groove depth on load-carrying capacity of the spiral groove bearings are investigated by orthogonal experiment design. The experimental results show that film height is the most remarkable factor to the load-carrying capacity. The variation tendency of load-carrying capacity reveals that the best combination of geometry is the one with groove number of 8, film height 0.03 mm and groove depth 0.08 mm. The velocity and pressure distributions in spiral groove bearings are also analyzed, and the analysis result shows that the distributions are in conformity with the design of the blood pump based on the principle of hydrodynamic bearing. The displacement of the rotor with the best combination parameters is tested by using laser displacement sensors, the testing result shows that the suspending performance is satisfactory both in axial and radial directions. This research proposes a bearing design method which has sufficient load-carrying capacity to support rotor as an effective passive hydrodynamic bearing.

  11. Analysis of a new PM motor design for a rotary dynamic blood Pump.

    PubMed

    Xu, L; Wang, F; Fu, M; Medvedev, A; Smith, W A; Golding, L A

    1997-01-01

    The permanent magnet (PM) motor for a rotary dynamic blood pump requires high power density to coordinate the motor size with the limited pump space and high efficiency to reduce the size and weight of the associated batteries. The motor also serves as a passive axial magnetic thrust bearing, a reacting hydraulic force, and provides a stabilizing force for the radial journal bearing. This article presents analysis of a new PM motor for the blood pump application. High power density is achieved by using the Halbach magnetic array, and high efficiency is accomplished by optimizing the rotor magnet assembly and the stator slots/windings. While both radial and axial forces are greatly enhanced, pulsating components of the torque and force are also significantly reduced.

  12. Design of an artificial left ventricular muscle: an innovative way to actuate blood pumps?

    PubMed

    Van Der Smissen, Benjamin; Claessens, Tom; Verdonck, Pascal; Van Ransbeeck, Peter; Segers, Patrick

    2009-06-01

    Blood pumps assist or take over the pump function of a failing heart. They are essentially activated by a pusher plate, a pneumatic compression of collapsible sacs, or they are driven by centrifugal pumps. Blood pumps relying upon one of these actuator mechanisms do not account for realistic wall deformation. In this study, we propose an innovative design of a blood pump actuator device which should be able to mimic fairly well global left ventricular (LV) wall deformation patterns in terms of circumferential and longitudinal contraction, as well as torsion. In order to reproduce these basic wall deformation patterns in our actuator device, we designed a novel kind of artificial LV "muscle" composed of multiple actively contracting cells. Its contraction is based on a mechanism by which pressurized air, inside such a cell, causes contraction in one direction and expansion perpendicular to this direction. The organization and geometry of the contractile cells within one artificial LV muscle, the applied pressure in the cells, and the governing LV loading conditions (preload and afterload) together determine the global deformation of the LV wall. Starting from a simple plastic bag, an experimental model based on the above mentioned principle was built and connected to a lumped hydraulic model of the vascular system (including compliance and resistance). The wall deformation pattern of this device was validated visually and its pump performance was studied in terms of LV volume and pressure and heart rate. Our experimental results revealed (i) a global LV motion resembling a real LV, and (ii) a close correlation between our model and a real LV in terms of end-systolic volume and pressure, end-diastolic volume and pressure, stroke volume, ejection fraction and pressure-volume relationship. Our proposed model appears promising and it can be considered as a step forward when compared to currently applied actuator mechanisms, as it will likely result in more physiological

  13. In vitro hematological testing of rotary blood pumps: remarks on standardization and data interpretation.

    PubMed

    Mueller, M R; Schima, H; Engelhardt, H; Salat, A; Olsen, D B; Losert, U; Wolner, E

    1993-02-01

    Pump test procedures using blood will have to meet several standards not only to obtain reliable results in vitro but also to allow comparison of results of different investigators. This article reviews some of the issues that should be considered in pump testing, especially referring to the discussions held at the International Workshops on Rotary Blood Pumps in 1988 and 1991. The test loop itself should meet some requirements such as constant physiological temperature, standardized circulating volume, control of pressure and flow, and exact definition of the blood-contacting surface. Specifications have to be made concerning the test fluid blood, including sampling technique, anticoagulation, blood gases, pH, and glucose level. Only fresh blood should be used. Heparin is recommended for anticoagulation because it will be used also in vivo. Different procedures for cleaning and rinsing of plastic materials for reuse are mentioned. Bacterial overgrowth, which can lead to extreme oxygen consumption and acidosis, may be avoided through addition of antibiotics (e.g., gentamicin). To be able to compare data of the different working groups, a new modified index of hemolysis (MIH) has been defined.

  14. Development and application of soil coupled heat pump

    NASA Astrophysics Data System (ADS)

    Liu, Lu

    2017-05-01

    Soil coupled heat pump technology is a new clean heating mode, is the world's most energy efficient heating one of the ways. And because of the use of renewable geothermal resources with high heating performance so more and more people's attention. Although the use of soil-coupled heat pumps has been in use for more than 50 years (the first application in the United States), the market penetration of this technology is still in its infancy. This paper will focus on the development, characteristics and application of the coupled heat pump.

  15. Well development by jetting using coiled tubing and simultaneous pumping.

    PubMed

    Rosberg, Jan-Erik; Bjelm, Leif

    2009-01-01

    During flow testing of a deep, 1927-m, gravel packed screen completed well, it became apparent that well development was needed to increase productivity. A hydrojetting system using coiled tubing in combination with simultaneous pumping was developed and tested and found to be successful. To verify whether the jetting improved the well, the results of a pumping test conducted before and after the jetting operation are compared. In addition, flowmeter logging and hydraulic properties obtained from pumping tests conducted during the jetting operation were also used to verify the improvements. Hydrojetting in combination with simultaneous pumping proved to be an effective cleaning method. After 100 min of pumping, around 110 m less drawdown and 15 L/s higher average flow rate were obtained compared to the values before the jetting operation. The skin factor was positive before the jetting operation and negative thereafter, thus providing additional evidence of improvements of the well. The flowmeter data also confirmed the improvements and were valuable in optimizing the jetting operation. It was also found, from the short-term pumping tests conducted during the jetting operation, that the Hantush-Jacob method for leaky confined aquifers is a valuable indicator of the well development. The combination of methods used for the well development in this case can easily be applied on other deep well projects to obtain a controlled and time-efficient well development.

  16. PUMPS

    DOEpatents

    Thornton, J.D.

    1959-03-24

    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  17. Application of Drag-Reducing Polymer Solutions as Test Fluids for In Vitro Evaluation of Potential Blood Damage in Blood Pumps

    PubMed Central

    Daly, Amanda R.; Sobajima, Hideo; Olia, Salim E.; Takatani, Setsuo; Kameneva, Marina V.

    2011-01-01

    In vitro evaluation of the potential of a circulatory-assist device to damage blood cells has generally been performed using blood from various species. Problems with this approach include the variability of blood sensitivity to mechanical stress in different species, preparation of blood including the adjustment of hematocrit to a standard value, changes in the mechanical properties of blood that occur during storage, and necessity to pool blood samples to obtain an adequate amount of blood for in vitro circulating systems. We investigated whether the mechanical degradation of a drag-reducing polymer (DRP) solution resulting in the loss of drag-reducing ability can indicate the degree of shear-induced blood damage within blood pumps. DRP solution (polyethylene oxide, 4,500 kDa, 1,000 ppm) or porcine blood were driven through a turbulent flow system by a centrifugal pump, either the Bio-Pump BPX-80 (Medtronic, Inc.) or CentriMag (Levitronix LLC) at a constant pressure gradient of 300 mm Hg for 120 minutes. DRP mechanical degradation was evaluated by reduction of flow rate and solution viscosity. A proposed index of DRP mechanical degradation (PDI) is similar to the normalized index of hemolysis (NIH) typically used to quantify the results of in vitro testing of blood pumps. Results indicate that the mechanical degradation of DRP solutions may provide a sensitive standard method for the evaluation of potential blood trauma produced by blood pumps without the use of blood. PMID:20019596

  18. Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump.

    PubMed

    Antaki, J F; Diao, C-G; Shu, F-J; Wu, J-C; Zhao, R; Kameneva, M V

    2008-05-01

    A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump. A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50-200 microm) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens (40x), mercury lamp, and high-resolution charge-coupled device camera electronically triggered by the rotation of the impeller. Experiments with 7 microm fluorescent particles revealed the influence of the gap dimension on the trajectory across the blade thickness. The lateral component of velocity (perpendicular to the blade) was dramatically enhanced in the 50 microm gap compared with the 200 microm gap, thereby reducing the exposure time. Studies with diluted bovine blood (Ht = 0.5 per cent) showed that the concentration of cells traversing the gap is also reduced dramatically (30 per cent) as the blade tip clearance is reduced from 200 microm to 50 microm. These results motivate further investigation into the microfluidic phenomena responsible for cellular trauma within turbodynamic blood pumps.

  19. Flow-Field Simulations and Hemolysis Estimates for the Food and Drug Administration Critical Path Initiative Centrifugal Blood Pump.

    PubMed

    Heck, Margaret L; Yen, Allen; Snyder, Trevor A; O'Rear, Edgar A; Papavassiliou, Dimitrios V

    2017-02-07

    The design of blood pumps for use in ventricular assist devices, which provide life-saving circulatory support in patients with heart failure, require remarkable precision and attention to detail to replicate the functionality of the native heart. The United States Food and Drug Administration (FDA) initiated a Critical Path Initiative to standardize and facilitate the use of computational fluid dynamics in the study and development of these devices. As a part of the study, a simplified centrifugal blood pump model generated by computer-aided design was released to universities and laboratories nationwide. The effects of changes in fluid rheology due to temperature, hematocrit, and turbulent flow on key metrics of the FDA pump were examined in depth using results from a finite volume-based commercial computational fluid dynamics code. Differences in blood damage indices obtained using Eulerian and Lagrangian formulations were considered. These results are presented and discussed awaiting future validation using experimental results, which will be released by the FDA at a future date. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  20. Development of syringe pump assisted headspace sampler.

    PubMed

    Go, Un Jeong; Eom, In-Yong

    2014-09-26

    This report describes a new platform for headspace sampling technique, i.e. a syringe pump assisted headspace sampler (SPHS). The stand type pump's syringe itself was used as a sealed sample vial and a needle trap device (NTD) was adopted as a miniaturized sorbent tube. The NTD was directly used to inject trapped VOCs into a gas chromatograph. The proposed sampler was designed to take a whole headspace volume instead of a portion of it so as to enhance easily the extraction efficiency. The performance of the SPHS-NTD system was evaluated and compared with the solid-phase microextraction (SPME) with a static headspace (HS) sampling technique. Calibration curves were obtained for aqueous TEX (toluene, ethylbenzene, and o-xylene) solutions in the concentration range of ∼0.1-45 ng/mL. The calculated limit of detections (LOD, S/N=3) for TEX were 0.13 ng/mL or less. This SPHS-NTD was successfully applied to analyze aqueous TEX in river water samples and showed highly good recovery ranged from 97.2% to 105.8% for all tested VOCs.

  1. Considerations and problems in the development of the mini-spindle pump.

    PubMed

    Hager, J; Koller, J; Gschnitzer, F; Fitz, A; Klima, G; Brandstaetter, F

    1995-07-01

    The premise for the development of the mini-spindle pump, planned as an implantable device for assisted circulation, was to transport 4 L of water/min in mock circulation with a speed of 12-15,000 rpm against an afterload of 90 mm Hg. After calculations, the resulting first prototype had a spindle rotor with 3 threads (outer diameter, 18 mm; inner diameter, 6.2 mm; length, 45 mm) in a U-shaped housing, driven by an electric motor with a cooling system. In mock circulation, this pump moved 7.8 L of water/min at 18,000 rpm. To avoid animal experiments, its influence on the blood was tested in a Maxima oxygenator. The device circulated 4.2 L of blood/min with the same speed. Because of its high traumatic hemolysis rate (> 250 mg% of free hemoglobin after 7 h of pumping), the rotor was modified, first without effect at 2.5 threads and then at 4 threads. In addition, in this third prototype, the flow direction was reversed. This prototype was more effective (4.3 L of blood/min at 12,000 rpm in the oxygenator) and the hemolysis rate, after a pumping duration of 8 h, could only be reduced to 180 mg% of free hemoglobin. As a result, a fourth prototype was developed (i.e., the U-shape of the housing was abandoned). This device functioned better than the third prototype (4.5 L of blood/min at 12,000 rpm in the oxygenator), but the blood trauma increased (220 mg% of free hemoglobin after 7 h of pumping).(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Viscosity-adjusted estimation of pressure head and pump flow with quasi-pulsatile modulation of rotary blood pump for a total artificial heart.

    PubMed

    Yurimoto, Terumi; Hara, Shintaro; Isoyama, Takashi; Saito, Itsuro; Ono, Toshiya; Abe, Yusuke

    2016-09-01

    Estimation of pressure and flow has been an important subject for developing implantable artificial hearts. To realize real-time viscosity-adjusted estimation of pressure head and pump flow for a total artificial heart, we propose the table estimation method with quasi-pulsatile modulation of rotary blood pump in which systolic high flow and diastolic low flow phased are generated. The table estimation method utilizes three kinds of tables: viscosity, pressure and flow tables. Viscosity is estimated from the characteristic that differential value in motor speed between systolic and diastolic phases varies depending on viscosity. Potential of this estimation method was investigated using mock circulation system. Glycerin solution diluted with salty water was used to adjust viscosity of fluid. In verification of this method using continuous flow data, fairly good estimation could be possible when differential pulse width modulation (PWM) value of the motor between systolic and diastolic phases was high. In estimation under quasi-pulsatile condition, inertia correction was provided and fairly good estimation was possible when the differential PWM value was high, which was not different from the verification results using continuous flow data. In the experiment of real-time estimation applying moving average method to the estimated viscosity, fair estimation could be possible when the differential PWM value was high, showing that real-time viscosity-adjusted estimation of pressure head and pump flow would be possible with this novel estimation method when the differential PWM value would be set high.

  3. Modeling of a dielectric elastomer diaphragm for a prosthetic blood pump

    NASA Astrophysics Data System (ADS)

    Goulbourne, Nakhiah; Frecker, Mary I.; Mockensturm, Eric M.; Snyder, Alan J.

    2003-07-01

    The electromechanical behavior of dielectric elastomers is to be exploited for medical application in artificial blood pumps. It is required that the pump diaphragm achieves a swept volume increase of 70 cc into a systolic pressure of 120 mmHg with the main design objective being volumetric efficiency. As such, a model that accommodates large deformation behavior is used. In order to design prosthetic blood pumps that closely mimic the natural pumping chambers of the heart, a dielectric elastomer diaphragm design is proposed. The elastomer's change in shape in response to the applied electric field will permit it to be the active element of the pump just as the ventricular walls are in the natural heart. A comprehensive analytical model that accounts for the combined elastic and dielectric behavior of the membrane is used to compute the stresses and deformations of the inflated membrane. Dielectric elastomers are often pre-strained in order to obtain optimal electromechanical performance. The resulting model incorporates pre-strain and shows how system parameters such as pre-strain, pressure, electric field, and edge constraints affect membrane deformation. The model predicts more than adequate volume displacement for moderate pre-strain of the elastomer.

  4. PIV measurements of flow in a centrifugal blood pump: time-varying flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Measurements of the time-varying flow in a centrifugal blood pump operating as a left ventricular assist device (LVAD) are presented. This includes changes in both the pump flow rate as a function of the left ventricle contraction and the interaction of the rotating impeller and fixed exit volute. When operating with a pulsing ventricle, the flow rate through the LVAD varies from 0-11 L/min during each cycle of the heartbeat. Phase-averaged measurements of mean velocity and some turbulence statistics within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser, are reported at 20 phases of the cardiac cycle. The transient flow fields are compared to the constant flow rate condition that was reported previously in order to investigate the transient effects within the pump. It is shown that the quasi-steady assumption is a fair treatment of the time varying flow field in all regions of this representative pump, which greatly simplifies the comprehension and modeling of this flow field. The measurements are further interpreted to identify the effects that the transient nature of the flow field will have on blood damage. Although regions of recirculation and stagnant flow exist at some phases of the cardiac cycle, there is no location where flow is stagnant during the entire heartbeat.

  5. Non-invasive estimation and control of inlet pressure in an implantable rotary blood pump for heart failure patients.

    PubMed

    Alomari, A H; Savkin, A V; Ayre, P J; Lim, E; Mason, D G; Salamonsen, R F; Fraser, J F; Lovell, N H

    2011-08-01

    We propose a dynamical model for mean inlet pressure estimation in an implantable rotary blood pump during the diastolic period. Non-invasive measurements of pump impeller rotational speed (ω), motor power (P), and pulse width modulation signal acquired from the pump controller were used as inputs to the model. The model was validated over a wide range of speed ramp studies, including (i) healthy (C1), variations in (ii) heart contractility (C2); (iii) afterload (C2, C3, C4), and (iv) preload (C5, C6, C7). Linear regression analysis between estimated and extracted mean inlet pressure obtained from in vivo animal data (greyhound dogs, N = 3) resulted in a highly significant correlation coefficients (R(2) = 0.957, 0.961, 0.958, 0.963, 0.940, 0.946, and 0.959) and mean absolute errors of (e = 1.604, 2.688, 3.667, 3.990, 2.791, 3.215, and 3.225 mmHg) during C1, C2, C3, C4, C5, C6, and C7, respectively. The proposed model was also used to design a controller to regulate mean diastolic pump inlet pressure using non-invasively measured ω and P. In the presence of model uncertainty, the controller was able to track and settle to the desired input within a finite number of sampling periods and minimal error (0.92 mmHg). The model developed herein will play a crucial role in developing a robust control system of the pump that detects and thus avoids undesired pumping states by regulating the inlet pressure within a predefined physiologically realistic limit.

  6. Theoretical foundations of a Starling-like controller for rotary blood pumps.

    PubMed

    Salamonsen, Robert Francis; Lim, Einly; Gaddum, Nicholas; AlOmari, Abdul-Hakeem H; Gregory, Shaun David; Stevens, Michael; Mason, David Glen; Fraser, John F; Timms, Daniel; Karunanithi, Mohan K; Lovell, Nigel Hamilton

    2012-09-01

    A clinically intuitive physiologic controller is desired to improve the interaction between implantable rotary blood pumps and the cardiovascular system. This controller should restore the Starling mechanism of the heart, thus preventing overpumping and underpumping scenarios plaguing their implementation. A linear Starling-like controller for pump flow which emulated the response of the natural left ventricle (LV) to changes in preload was then derived using pump flow pulsatility as the feedback variable. The controller could also adapt the control line gradient to accommodate longer-term changes in cardiovascular parameters, most importantly LV contractility which caused flow pulsatility to move outside predefined limits. To justify the choice of flow pulsatility, four different pulsatility measures (pump flow, speed, current, and pump head pressure) were investigated as possible surrogates for LV stroke work. Simulations using a validated numerical model were used to examine the relationships between LV stroke work and these measures. All were approximately linear (r(2) (mean ± SD) = 0.989 ± 0.013, n = 30) between the limits of ventricular suction and opening of the aortic valve. After aortic valve opening, the four measures differed greatly in sensitivity to further increases in LV stroke work. Pump flow pulsatility showed more correspondence with changes in LV stroke work before and after opening of the aortic valve and was least affected by changes in the LV and right ventricular (RV) contractility, blood volume, peripheral vascular resistance, and heart rate. The system (flow pulsatility) response to primary changes in pump flow was then demonstrated to be appropriate for stable control of the circulation. As medical practitioners have an instinctive understanding of the Starling curve, which is central to the synchronization of LV and RV outputs, the intuitiveness of the proposed Starling-like controller will promote acceptance and enable rational

  7. The Effect of Geometry on the Efficiency and Hemolysis of Centrifugal Implantable Blood Pumps.

    PubMed

    Mozafari, Sahand; Rezaienia, Mohammad A; Paul, Gordon M; Rothman, Martin T; Wen, Pihua; Korakianitis, Theodosios

    The application of centrifugal pumps as heart assist devices imposes design limitations on the impeller geometry. Geometry and operating parameters will affect the performance and the hemocompatibility of the device. Among all the parameters affecting the hemocompatibility, pressure, rotational speed, blade numbers, angle, and width have significant impact on the blood trauma. These parameters directly (pressure, speed) and indirectly (geometry) affect the efficiency of the pump as well. This study describes the experimental investigation on geometric parameters and their effect on the performance of small centrifugal pumps suitable for Mechanical Circulatory Support (MCS) devices. Experimental and numerical techniques were implemented to analyze the performance of 15 centrifugal impellers with different characteristics. The effect of each parameter on the pump performance and hemolysis was studied by calculating the normalized index of hemolysis (NIH) and the shear stress induced in each pump. The results show five and six blades, 15-35° outlet angle, and the lowest outlet width that meets the required pressure rise are optimum values for an efficient hemocompatible pump.

  8. Development of the Permian Basin beam pump failure database

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammed Mahbubur

    Artificial Lift Energy Optimization Consortium (ALEOC) was formed by eleven oil companies operating in the Permian Basin with the primary goal of improving oil field operations through sharing experiences. Beam pumping system received special attention because it is the most widely used artificial lift method in the Permian Basin as well as in the world. The combined effort to optimize beam pumping system calls for the creation of a central database, which will hold beam pump related data from diverse sources and will offer ways to analyze the data to obtain valuable insight about the nature, magnitude and trend of beam pump failure. The database mentioned above has been created as part of this work. The database combines beam pump failure data from about 25,000 wells owned by different companies into a single, uniform and consistent format. Moreover, two front-end computer applications have been developed to interact with the database, to run queries, and to make plots form the query results. One application is designed for desktop, while the other one is designed for the Internet. Both applications calculate failure frequencies of pump, rod, and tubing, and summarize the results in various ways. Thus the database and the front-end applications together provide a powerful means for analyzing beam pump failure data. Much useful information can be gathered from the database, such as the most vulnerable component in the system, the best and the worst performers, and the most troublesome operating area. Such information can be used for benchmarking performance, identifying best design/operational practices, design modification, and long term production planning. Results from data analysis show that the pump has the highest probability to fail in a beam pumping system, followed by the rod string and the tubing string. The overall failure in the Permian Basin shows a general decline with time.

  9. Fluctuations in syringe-pump infusions: association with blood pressure variations in infants.

    PubMed

    Capes, D F; Dunster, K R; Sunderland, V B; McMillan, D; Colditz, P B; McDonald, C

    1995-08-01

    Flow continuity of two brands of syringe pumps and four brands of syringes was studied as a possible cause of hemodynamic fluctuations observed in neonates. Cyclical fluctuations were observed in the blood pressure of 14 neonates receiving dopamine infusions by syringe pump at flow rates from 0.2 to 1 mL/hr. Atom 235 and IVAC 770 pumps and various sizes of Terumo, Becton Dickinson, Omnifix, and IVAC syringes were evaluated. Flow continuity was assessed by using a gravimetric technique. The force needed to initiate and maintain syringe plunger motion was also measured. Noncontinuous flow was encountered most commonly with Terumo syringes, which delivered boluses at regular intervals at flow rates up to 5 mL/hr. The interval was dependent on flow rate and was similar to the time between the blood pressure fluctuations observed clinically. The syringe plunger force exhibited regular fluctuations indicative of the plunger sticking, and simultaneous measurement of flow established a direct temporal relationship with boluses. The other syringes tested did not exhibit such fluctuations. No differences were found between the two syringe pumps. Syringe plunger sticking, resulting in intermittent boluses and potential blood pressure fluctuations, may occur at low flow rates and with certain syringe brands. This appeared to be the cause of hemodynamic fluctuations in neonates receiving dopamine infusions.

  10. Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller.

    PubMed

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yambe, Tomoyuki; Imachi, Kou; Yamane, Takashi

    2013-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump with a semi-open impeller for long-term circulatory assist. The pump uses hydrodynamic bearings to enhance durability and reliability without additional displacement-sensors or control circuits. However, a narrow bearing gap of the pump has a potential for hemolysis. The purpose of this study is to develop the hydrodynamically levitated centrifugal blood pump with a semi-open impeller, and to evaluate the effect of a bearing gap on hemolytic property. The impeller levitates using a spiral-groove type thrust bearing, and a herringbone-groove type radial bearing. The pump design was improved by adopting a step type thrust bearing and optimizing the pull-up magnetic force. The pump performance was evaluated by a levitation performance test, a hemolysis test and an animal experiment. In these tests, the bearing gap increased from 1 to 63 μm. In addition, the normalized index of hemolysis (NIH) improved from 0.415 to 0.005 g/100 l, corresponding to the expansion of the bearing gap. In the animal experiment for 24 h, the plasma-free hemoglobin remained within normal ranges (<4.0 mg/dl). We confirmed that the hemolytic property of the pump was improved to the acceptable level by expanding the bearing gap greater than 60 μm.

  11. Ice-maker heat pump development

    NASA Astrophysics Data System (ADS)

    Baxter, V. D.

    1980-09-01

    Four test unit ice maker heat pumps (IMHPs) were tested under the annual cycle energy system (ACES) program. Performance results on the effects of harvesting scheme, plate loading, and cycling operation were compared. The ice packing density of IMHPs was also studied and compared with that of ice manufactured by commerical ice makers and brine chiller ACES. Three harvesting schemes were tested: hot gas, stored refrigerant, and dual fluid, off cycle. The hot gas scheme tended to penalize excessively the heating output of the system. Stored refrigerant schemes eliminated that problem but caused compressor failures due to flood-back and oil dilution. The dual fluid schemes exhibited no such problems and demonstrated an ability to harvest during compressor off cycles. Therefore, it was concluded that dual fluid, off cycle schemes are the best for use with IMPHs. Plate loading tests in which compressor speed and evaporator size are varied clearly showed that evaporator plate loading should be as low as possible.

  12. New mechanism to reduce the size of the monopivot magnetic suspension blood pump: direct drive mechanism.

    PubMed

    Yamane, T; Nishida, M; Kijima, T; Maekawa, J

    1997-07-01

    Size reduction of the monopivot magnetic suspension blood pump has been achieved by reducing the size of the magnetic suspension and employing a direct drive mechanism in place of a brushless DC motor and a magnetic coupling. The flow has also been improved using a closed hollow impeller to remove flow obstruction at the inlet and using radial straight vanes to reduce the impeller speed by 30%. Hemolysis testing was conducted for the new models. Results showed that model DD1 presented only a slightly higher level of hemolysis than a regular extracorporeal centrifugal pump.

  13. Development of a jet pump-assisted arterial heat pipe

    NASA Technical Reports Server (NTRS)

    Bienert, W. B.; Ducao, A. S.; Trimmer, D. S.

    1977-01-01

    The development of a jet pump assisted arterial heat pipe is described. The concept utilizes a built-in capillary driven jet pump to remove vapor and gas from the artery and to prime it. The continuous pumping action also prevents depriming during operation of the heat pipe. The concept is applicable to fixed conductance and gas loaded variable conductance heat pipes. A theoretical model for the jet pump assisted arterial heat pipe is presented. The model was used to design a prototype for laboratory demonstration. The 1.2 m long heat pipe was designed to transport 500 watts and to prime at an adverse elevation of up to 1.3 cm. The test results were in good agreement with the theoretical predictions. The heat pipe carried as much as 540 watts and was able to prime up to 1.9 cm. Introduction of a considerable amount of noncondensible gas had no adverse effect on the priming capability.

  14. PIV measurements of flow in a centrifugal blood pump: steady flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Magnetically suspended left ventricular assist devices have only one moving part, the impeller. The impeller has absolutely no contact with any of the fixed parts, thus greatly reducing the regions of stagnant or high shear stress that surround a mechanical or fluid bearing. Measurements of the mean flow patterns as well as viscous and turbulent stresses were made in a shaft-driven prototype of a magnetically suspended centrifugal blood pump at several constant flow rates (3-9 L/min) using particle image velocimetry (PIV). The chosen range of flow rates is representative of the range over which the pump may operate while implanted. Measurements on a three-dimensional measurement grid within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser are reported. The measurements are used to identify regions of potential blood damage due to high shear stress and/or stagnation of the blood, both of which have been associated with blood damage within artificial heart valves and diaphragm-type pumps. Levels of turbulence intensity and Reynolds stresses that are comparable to those in artificial heart valves are reported. At the design flow rate (6 L/min), the flow is generally well behaved (no recirculation or stagnant flow) and stress levels are below levels that would be expected to contribute to hemolysis or thrombosis. The flow at both high (9 L/min) and low (3 L/min) flow rates introduces anomalies into the flow, such as recirculation, stagnation, and high stress regions. Levels of viscous and Reynolds shear stresses everywhere within the pump are below reported threshold values for damage to red cells over the entire range of flow rates investigated; however, at both high and low flow rate conditions, the flow field may promote activation of the clotting cascade due to regions of elevated shear stress adjacent to separated or stagnant flow.

  15. Non-invasive estimation of pulsatile flow and differential pressure in an implantable rotary blood pump for heart failure patients.

    PubMed

    AlOmari, A H; Savkin, A V; Karantonis, D M; Lim, E; Lovell, N H

    2009-04-01

    We propose dynamical models for pulsatile flow and head estimation in an implantable rotary blood pump. Pulsatile flow and head data were obtained using a circulatory mock loop where fluid solutions with different values of viscosities were used as a blood analogue with varying haematocrit (HCT). Noninvasive measurements of power and pump speed were used with HCT values as inputs to the flow model while the estimated flow was used with the speed as inputs to a head estimation model. Linear regression analysis between estimated and measured flows obtained from a mock loop resulted in a highly significant correlation (R2=0.982) and a mean absolute error (e) of 0.323 L min(-1), while for head, R2=0.933 and e=7.682 mmHg were obtained. R2=0.849 and e=0.584 L min(-1) were obtained when the same model derived in the mock loop was used for flow estimation in ex vivo porcine data (N=6). Furthermore, in the steady state, the solution of the presented flow model can be described by a previously designed and verified static model. The models developed herein will play a vital role in developing a robust control system of the pump flow coping with changing physiological demands.

  16. A magnetic fluid seal for rotary blood pumps: effects of seal structure on long-term performance in liquid.

    PubMed

    Mitamura, Yoshinori; Takahashi, Sayaka; Amari, Shuichi; Okamoto, Eiji; Murabayashi, Shun; Nishimura, Ikuya

    2011-03-01

    A magnetic fluid (MF) seal enables mechanical contact-free rotation of the shaft and hence has excellent durability. The performance of an MF seal, however, has been reported to decrease in liquids. We developed an MF seal that has a "shield" mechanism, and a new MF with a higher magnetization of 47.9 kA/m. The sealing performance of the MF seal installed in a rotary blood pump was studied. Three types of MF seals were used. Seal A was a conventional seal without a shield. Seal B had the same structure as that of Seal A, but the seal was installed at 1 mm below liquid level. Seal C was a seal with a shield and the MF was set at 1 mm below liquid level. Seal A failed after 6 and 11 days. Seal B showed better results (20 and 73 days). Seal C showed long-term durability (217 and 275 days). The reason for different results in different seal structures was considered to be different flow conditions near the magnetic fluid. Fluid dynamics near the MF in the pump were analyzed using computational fluid dynamics (CFD) software. We have developed an MF seal with a shield that works in liquid for >275 days. The MF seal is promising as a shaft seal for rotary blood pumps.

  17. Modeling Study of the Failing Heart and its Interaction with an Implantable Rotary Blood Pump

    PubMed Central

    Ramachandran, Deepa P.; Luo, Chuan; Ma, Tony S.; Clark, John W.

    2016-01-01

    The effectiveness of clinical diagnosis and treatment of heart failure is a direct function of clinical signs that can be measured in a patient within cost and safety constraints. Large-scale mathematical modeling can be a key tool in revealing important, measurable clinical signs of heart failure, furthering medical understanding and development of treatment. In the first part of this study we have created two models of left heart failure diastolic and systolic, using our human cardiovascular-respiratory system (H-CRS) model, and we present a comparison of the two types with emphasis on novel and differentiating clinical signs, such as tricuspid flow and septal motion. In the event of compromised left ventricular performance, mechanical left ventricular assist devices (LVAD) are often implanted to augment or completely replace the pumping action of the left ventricle (LV). One such type is the implantable rotary blood pump (iRBP). Several design issues related to the iRBP are difficult to study experimentally due to procedure complexity and limitations in animal models of heart failure [2]. Therefore, modeling has become a key tool in iRBP development. In the second part of this study, we have introduced an iRBP model based on [1]-[2] in the systolic failing heart to study the interactions. We consider optimal motor settings for different levels of LV assistance, the effects of the iRBP on the right heart, septum, and pulmonary circulation. Our model results align with those reported in [1]-[2]. Improvement in cardiac output, pulmonary congestion, and heart work are seen with the iRBP. We observe lowered septal assistance to RV and LV ejection with increasing pump speeds, elevating right ventricular (RV) work, reducing LVET, and causing ventricular mechanical dyssynchrony in ejection. These results suggest right heart compromise via the septum s reduced role with the introduction of an iRBP. This work emphasizes the critical role of modeling in heart failure and

  18. Blood-mimicking delivery in polygonal structure of inner quadrupletip microneedle with valveless micro-pump

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. D.; Yunos, Y. S.; Rigit, A. R. H.; Mohtadzar, N. A. A.; Watanabe, N.; Sunami, Y.; Rahman, M. R. A.; Wong, L. K.; Mohtar, M. Z.

    2017-04-01

    This paper presents a titanium quadrupletip micro-needle integrated with a micro-pump with different inner designs, length and diameter of the micro-channels to measure and maximize the velocity flow in the micro-needle as blood delivered into human body. Titanium is used as the material of the micro-needle which are also the common material in manufacturing of micro-needle. The advancement of micro-needle technologies is improved in penetrating human outermost skin, stratum corneum and further to human blood vessels. The micro-needles with channel inner design of circular, square, hexagon, and dodecagon with quadruple tip designs are drawn with inner diameter parameter of 150μm and 100μm with two different channel length which are 10mm and 25mm. The characteristics of blood delivery in geometrically changed inner designs affect the output velocity in microneedle when the micropump is operating. The results showed that, when it is pumped at 0.04m/s, the blood velocity improved by 5.6% than when the pump is increased by 30% of its capacity. This is due to the backflow generated in the micropump.

  19. Sodium pump α2 subunits control myogenic tone and blood pressure in mice

    PubMed Central

    Zhang, Jin; Lee, Moo Yeol; Cavalli, Maurizio; Chen, Ling; Berra-Romani, Roberto; Balke, C William; Bianchi, Giuseppe; Ferrari, Patrizia; Hamlyn, John M; Iwamoto, Takahiro; Lingrel, Jerry B; Matteson, Donald R; Wier, W Gil; Blaustein, Mordecai P

    2005-01-01

    A key question in hypertension is: How is long-term blood pressure controlled? A clue is that chronic salt retention elevates an endogenous ouabain-like compound (EOLC) and induces salt-dependent hypertension mediated by Na+/Ca2+ exchange (NCX). The precise mechanism, however, is unresolved. Here we study blood pressure and isolated small arteries of mice with reduced expression of Na+ pump α1 (α1+/−) or α2 (α2+/−) catalytic subunits. Both low-dose ouabain (1–100 nm; inhibits only α2) and high-dose ouabain (≥1 μm; inhibits α1) elevate myocyte Ca2+ and constrict arteries from α1+/−, as well as α2+/− and wild-type mice. Nevertheless, only mice with reduced α2 Na+ pump activity (α2+/−), and not α1 (α1+/−), have elevated blood pressure. Also, isolated, pressurized arteries from α2+/−, but not α1+/−, have increased myogenic tone. Ouabain antagonists (PST 2238 and canrenone) and NCX blockers (SEA0400 and KB-R7943) normalize myogenic tone in ouabain-treated arteries. Only the NCX blockers normalize the elevated myogenic tone in α2+/− arteries because this tone is ouabain independent. All four agents are known to lower blood pressure in salt-dependent and ouabain-induced hypertension. Thus, chronically reduced α2 activity (α2+/− or chronic ouabain) apparently regulates myogenic tone and long-term blood pressure whereas reduced α1 activity (α1+/−) plays no persistent role: the in vivo changes in blood pressure reflect the in vitro changes in myogenic tone. Accordingly, in salt-dependent hypertension, EOLC probably increases vascular resistance and blood pressure by reducing α2 Na+ pump activity and promoting Ca2+ entry via NCX in myocytes. PMID:16166162

  20. Numerical Analysis of Blood Damage Potential of the HeartMate II and HeartWare HVAD Rotary Blood Pumps.

    PubMed

    Thamsen, Bente; Blümel, Bastian; Schaller, Jens; Paschereit, Christian O; Affeld, Klaus; Goubergrits, Leonid; Kertzscher, Ulrich

    2015-08-01

    Implantable left ventricular assist devices (LVADs) became the therapy of choice in treating end-stage heart failure. Although survival improved substantially and is similar in currently clinically implanted LVADs HeartMate II (HM II) and HeartWare HVAD, complications related to blood trauma are frequently observed. The aim of this study was to compare these two pumps regarding their potential blood trauma employing computational fluid dynamics. High-resolution structured grids were generated for the pumps. Newtonian flow was calculated, solving Reynolds-averaged Navier-Stokes equations with a sliding mesh approach and a k-ω shear stress transport turbulence model for the operating point of 4.5 L/min and 80 mm Hg. The pumps were compared in terms of volumes subjected to certain viscous shear stress thresholds, below which no trauma was assumed (von Willebrand factor cleavage: 9 Pa, platelet activation: 50 Pa, and hemolysis: 150 Pa), and associated residence times. Additionally, a hemolysis index was calculated based on a Eulerian transport approach. Twenty-two percent of larger volumes above 9 Pa were observed in the HVAD; above 50 Pa and 150 Pa the differences between the two pumps were marginal. Residence times were higher in the HVAD for all thresholds. The hemolysis index was almost equal for the HM II and HVAD. Besides the gap regions in both pumps, the inlet regions of the rotor and diffuser blades have a high hemolysis production in the HM II, whereas in the HVAD, the volute tongue is an additional site for hemolysis production. Thus, in this study, the comparison of the HM II and the HVAD using numerical methods indicated an overall similar tendency to blood trauma in both pumps. However, influences of turbulent shear stresses were not considered and effects of the pivot bearing in the HM II were not taken into account. Further in vitro investigations are required. Copyright © 2015 International Center for Artificial Organs and Transplantation and

  1. Optimal bearing gap of a multiarc radial bearing in a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    PubMed

    Kosaka, Ryo; Yasui, Kazuya; Nishida, Masahiro; Kawaguchi, Yasuo; Maruyama, Osamu; Yamane, Takashi

    2014-09-01

    We have developed a hydrodynamically levitated centrifugal pump as a bridge-to-decision device. The purpose of the present study is to determine the optimal bearing gap of a multiarc radial bearing in the developed blood pump for the reduction of hemolysis. We prepared eight pump models having bearing gaps of 20, 30, 40, 80, 90, 100, 180, and 250 μm. The driving conditions were set to a pressure head of 200 mm Hg and a flow rate of 4 L/min. First, the orbital radius of the impeller was measured for the evaluation of the impeller stability. Second, the hemolytic property was evaluated in an in vitro hemolysis test. As a result, the orbital radius was not greater than 15 μm when the bearing gap was between 20 and 100 μm. The relative normalized index of hemolysis (NIH) ratios in comparison with BPX-80 were 37.67 (gap: 20 μm), 0.95 (gap: 30 μm), 0.96 (gap: 40 μm), 0.82 (gap: 80 μm), 0.77 (gap: 90 μm), 0.92 (gap: 100 μm), 2.76 (gap: 180 μm), and 2.78 (gap: 250 μm). The hemolysis tended to increase at bearing gaps of greater than 100 μm due to impeller instability. When the bearing gap decreased from 30 to 20 μm, the relative NIH ratios increased significantly from 0.95 to 37.67 times (P < 0.01) due to high shear stress. We confirmed that the optimal bearing gap was determined between 30 and 100 μm in the developed blood pump for the reduction of hemolysis.

  2. Development of PACS Digital Pump and implications for other industries

    NASA Astrophysics Data System (ADS)

    Banister, M.; Vohnout, S.; Kenman, D.

    2007-04-01

    This paper discusses the development and system integration of the Pulse Activated Cell System (PACS) Digital Pump technology using 2 types of electro-activated polymer (EAP) actuators. This is a platform specifically developed for the integration of sensor feedback loops to create an autonomous fluidic monitoring, reaction and delivery system. Initial, proof of concept, performance testing results are discussed as well as development for a medical drug delivery device and higher volume infusion therapy device. Uses and applications of the technology in other industries is considered as the PAC System provides a new ability to pump single or multiple fluid flows in a single pump that is programmable with the ability to vary direction, pressure and flow rates. The result is digital control of fluidic delivery, testing and mixing in application scaleable product packages. This technology will lead to new low cost yet sophisticated fluidic processing products and devices for many industries.

  3. A hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: design of a hydrodynamic bearing.

    PubMed

    Mitamura, Yoshinori; Kido, Kazuyuki; Yano, Tetsuya; Sakota, Daisuke; Yambe, Tomoyuki; Sekine, Kazumitsu; OKamoto, Eiji

    2007-03-01

    To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear.

  4. Measurements of gap pressure and wall shear stress of a blood pump model.

    PubMed

    Chua, L P; Akamatsu, T

    2000-04-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial hearts. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and stationary surfaces. As the gap is only 0.2 mm in width, it is very difficult to conduct measurements with present instrumentation. An enlarged model with 5:1 ratio of the pump has been designed and constructed according to specifications. Dimensionless gap pressure measurements of the model are very close to the prototype. The measurements of wall shear stress of the fluid flow in the clearance gap between the impeller face and inlet casing of a blood pump model were accomplished through hot-wire anemometry and rotating disk apparatus. Regions of relatively high and low shear stresses are identified. These correspond to spots where the likelihood of hemolysis and thrombus formation is high. With the use of dimensional analysis, it is found that the highest wall shear stress is equivalent to 146 Pa which is much lower than the threshold value of 400 Pa for hemolysis reported in the literature.

  5. Physiological control of a rotary blood pump with selectable therapeutic options: control of pulsatility gradient.

    PubMed

    Arndt, Andreas; Nüsser, Peter; Graichen, Kurt; Müller, Johannes; Lampe, Bernhard

    2008-10-01

    A control strategy for rotary blood pumps meeting different user-selectable control objectives is proposed: maximum support with the highest feasible flow rate versus medium support with maximum ventricular washout and controlled opening of the aortic valve (AoV). A pulsatility index (PI) is calculated from the pressure difference, which is deduced from the axial thrust measured by the magnetic bearing of the pump. The gradient of PI with respect to pump speed (GPI) is estimated via online system identification. The outer loop of a cascaded controller regulates GPI to a reference value satisfying the selected control objective. The inner loop controls the PI to a reference value set by the outer loop. Adverse pumping states such as suction and regurgitation can be detected on the basis of the GPI estimates and corrected by the controller. A lumped-parameter computer model of the assisted circulation was used to simulate variations of ventricular contractility, pulmonary venous pressure, and aortic pressure. The performance of the outer control loop was demonstrated by transitions between the two control modes. Fast reaction of the inner loop was tested by stepwise reduction of venous return. For maximum support, a low PI was maintained without inducing ventricular collapse. For maximum washout, the pump worked at a high PI in the transition region between the opening and the permanently closed AoV. The cascaded control of GPI and PI is able to meet different control objectives and is worth testing in vitro and in vivo.

  6. An electric model with time varying resistance for a pneumatic membrane blood pump.

    PubMed

    Jin, Z; Qin, J

    1993-01-01

    To investigate the effects of an artificial heart and cardiac assist device on the cardiovascular system and determine the proper control method, an electrical model is an effective tool. An electric model with time varying resistance is proposed to represent a pneumatic membrane blood pump, by which the resistance of the valves in the pump is a function of time. The model is consistent over the whole cardiac cycle, and the important transitional processes between systole and diastole are considered. The calculated results based on this model are compared with the experimentally measured waveforms of the corresponding state-variables of a loaded pump, and the model parameters estimated using the least-squares criterion are compared with the measured physical values of corresponding functional parts. Results showed that this electric model is capable of representing a pneumatic membrane pump with quite satisfactory accuracy. They also showed that the transitional property of the valve resistance has a significant influence on the output characteristics of the pump.

  7. Improvement of hemocompatibility in centrifugal blood pump with hydrodynamic bearings and semi-open impeller: in vitro evaluation.

    PubMed

    Kosaka, Ryo; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku; Yamane, Takashi

    2009-10-01

    We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 microm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces.

  8. Effect of intra-aortic balloon pump on coronary blood flow during different balloon cycles support: A computer study.

    PubMed

    Aye, Thin Pa Pa; Htet, Zwe Lin; Singhavilai, Thamvarit; Naiyanetr, Phornphop

    2015-01-01

    Intra-aortic balloon pump (IABP) has been used in clinical treatment as a mechanical circulatory support device for patients with heart failure. A computer model is used to study the effect on coronary blood flow (CBF) with different balloon cycles under both normal and pathological conditions. The model of cardiovascular and IABP is developed by using MATLAB SIMULINK. The effect on coronary blood flow has been studied under both normal and pathological conditions using different balloon cycles (balloon off; 1:4; 1:2; 1:1). A pathological heart is implemented by reducing the left ventricular contractility. The result of this study shows that the rate of balloon cycles is related to the level of coronary blood flow.

  9. Differences between blood and a Newtonian fluid on the performance of a hydrodynamic bearing for rotary blood pumps.

    PubMed

    Amaral, Felipe; Egger, Christina; Steinseifer, Ulrich; Schmitz-Rode, Thomas

    2013-09-01

    Assuming that blood has a constant viscosity is a common practice when designing rotary blood pumps (RBPs), where shear stresses are generally higher than in the human body. This eases the design and allows numerical simulations and bench top experiments to be performed with Newtonian fluids. However, specific flow conditions may cause a change in cell distribution leading to an apparent lower blood viscosity. It has been observed that decreasing the vessel diameters and increasing flow velocities contribute to this effect. Because a hydrodynamic bearing operates under flow conditions following this pattern, it is important to verify whether this effect also takes place when this type of bearing is applied to a RBP. Because the operation of a hydrodynamic bearing depends directly on the fluid viscosity, a local change in cell distribution in the bearing gap can be reflected in changes in the bearing performance. In this work, a spiral groove hydrodynamic bearing was tested with porcine blood in a specially built test rig. The generated suspension force, cross flow, and bearing torque were recorded and compared with the reference response when using a solution of water and glycerol. Experiments with porcine blood yielded lower suspension forces, lower flows, and lower bearing torques than when using the glycerol solution. An explanation could be a lower apparent viscosity due to inhomogeneity of blood cell concentrations. Therefore, it is crucial to consider the effective blood viscosity when designing hydrodynamic bearings for RBPs and performing experiments. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

  10. Development and Optimized Design of Propeller Pump System & Structure with VFD in Low-head Pumping Station

    NASA Astrophysics Data System (ADS)

    Rentian, Zhang; Honggeng, Zhu; Arnold, Jaap; Linbi, Yao

    2010-06-01

    Compared with vertical-installed pumps, the propeller (bulb tubular) pump systems can achieve higher hydraulic efficiencies, which are particularly suitable for low-head pumping stations. More than four propeller pumping stations are being, or will be built in the first stage of the S-to-N Water Diversion Project in China, diverting water from Yangtze River to the northern part of China to alleviate water-shortage problems and develop the economy. New structures of propeller pump have been developed for specified pumping stations in Jiangsu and Shandong Provinces respectively and Variable Frequency Drives (VFDs) are used in those pumping stations to regulate operating conditions. Based on the Navier-Stokes equations and the standard k-e turbulent model, numerical simulations of the flow field and performance prediction in the propeller pump system were conducted on the platform of commercial software CFX by using the SIMPLEC algorithm. Through optimal design of bulb dimensions and diffuser channel shape, the hydraulic system efficiency has improved evidently. Furthermore, the structures of propeller pumps have been optimized to for the introduction of conventional as well as permanent magnet motors. In order to improve the hydraulic efficiency of pumping systems, both the pump discharge and the motor diameter were optimized respectively. If a conventional motor is used, the diameter of the pump casing has to be increased to accommodate the motor installed inside. If using a permanent magnet motor, the diameter of motor casing can be decreased effectively without decreasing its output power, thus the cross-sectional area is enlarged and the velocity of flowing water decreased favorably to reduce hydraulic loss of discharge channel and thereby raising the pumping system efficiency. Witness model tests were conducted after numerical optimization on specific propeller pump systems, indicating that the model system hydraulic efficiencies can be improved by 0.5%˜3.7% in

  11. Exercise studies in patients with rotary blood pumps: cause, effects, and implications for starling-like control of changes in pump flow.

    PubMed

    Salamonsen, Robert F; Pellegrino, Vincent; Fraser, John F; Hayes, Kate; Timms, Daniel; Lovell, Nigel Hamilton; Hayward, Christopher

    2013-08-01

    This multicenter study examines in detail the spontaneous increase in pump flow at fixed speed that occurs in exercise. Eight patients implanted with the VentrAssist rotary blood pump were subjected to maximal and submaximal cycle ergometry studies, the latter being completed with patients supine and monitored with right heart catheter and echocardiography. Maximal exercise studies conducted in each patient at three different pump speeds on separate days established initially the magnitude and consistency of increases in pump flow that correlated well with changes in heart rate. However, there was considerable variation, coefficients of variation for mean heart rate and pump flow being 47.9 and 49.3%, respectively. Secondly, these studies indicated that increasing pump flows caused significant improvements in maximal exercise capacity. An increase of 2.1 L/min (35%) in maximum blood flow caused 12 W (16%) further increase in achievable work, 1.26 (9.3%) mL/kg/min in maximal oxygen uptake, and 2.3 (23%) mL/kg/min in anaerobic threshold. Mean increases in lactate were 0.85 mm (24%), but mean B-type natiuretic peptide fell by 126 mm, (-78%). From submaximal supine exercise studies, multiple linear regression of pump flow on factors thought to underlie the spontaneous increase in pump flow indicated that it was associated with increases in heart rate (P = 0.039), pressure gradient across the left ventricle (P = 0.032), and right atrial pressure (P = 0.003). These changes have implications for the recently reported Starling-like controller for pump flow based on pump pulsatility values, which emulates the Starling curve relating pump output to left ventricular preload. Unmodified, the controller would not permit the full benefits of this effect to be afforded to patients implanted with rotary blood pumps. A modification to the pump control algorithm is proposed to eliminate this problem. © 2013, Copyright the Authors. Artificial Organs © 2013 Wiley

  12. [Insulin therapy by insulin pump: continuous or conventional self-blood glucose monitoring? ].

    PubMed

    Renard, E

    2003-04-01

    Use of portable pumps is increasing to achieve intensive insulin treatment. Beside unpredictable insulin absorption and insufficient reactivity to changes of insulin flow rate due to the subcutaneous route, this therapy is however limited by the lack of information on blood glucose level provided by self-blood glucose monitoring. Thus, patient interpretation only leads to speculative adaptation of pump flow rate. The lack of alert toward the risk of hypoglycemia or hyperglycemic ketogenic deviations can lead to the occurrence of deleterious metabolic distorsions, among which severe hypoglycemia stands in first rank. Starting experiences of continuous recording of interstitial glucose level by portable systems using glucose-oxidase allow on short time durations the identification of daily periods of poor metabolic control. Retrospective availability of information gives the possibility of more adequate treatment adaptations than conventional capillary blood glucose monitoring, but does not allow immediate prevention of metabolic events. Only devices providing real time or near-real time information to the patient can fulfill this function. However, the absence of tight parallelism between variations of interstitial and blood glucose levels may lead to erroneous decisions. A true continuous real time information on blood glucose level on long-term seems only expectable from implantable glucose sensors. Still under investigation, these systems should be able to insure vigilance toward the risk of hypo- and hyperglycemia on weekly or monthly periods. Initially used as complementary to capillary self-monitoring, their reliability should allow their use as substitutes for conventional monitoring, except for measurements aimed at signal calibration. Pump control by the sensor signal is conceivable if it corresponds to a direct, continuous, real time measurement of blood glucose, and subject to a simultaneous improvement of insulin infusion modes.

  13. Flow visualization in the outflow cannula of an axial blood pump.

    PubMed

    Liu, Guangmao; Zhang, Yan; Chen, Haibo; Sun, Hansong; Zhou, Jianye; Hu, Shengshou

    2014-01-01

    The properties of blood flow in the outflow cannula of an axial blood pump play a critical role in potential thrombus formation and vascular injury. In this study, an in vitro flow visualization technique using particle image velocimetry (PIV) was applied to investigate the flow characteristics in the outflow cannula of a FW-2 model axial pump. The two-dimensional (2-D) flow field in the axial central section and the three-dimensional (3-D) flow field in the whole outflow cannula were examined with the PIV system. Tests were carried out with a blood-mimic working fluid in the axial pump at a rotational speed of 8500 ± 20 rpm with a flow rate of 5 L/min. The velocity distribution in the outflow cannula was analyzed to evaluate the flow characteristics. There was no backflow or stagnant flow in the tested area, while the flow velocity rapidly increased outside the boundary layer. A spiral flow was observed near the boundary layer, but this was worn off within the tested area. Based on the results, hemolysis and thrombus formation in the cannula, and injury to aortic endothelium are unlikely to occur due to spiral flow.

  14. Development of an autoflow cruise control system for a centrifugal pump.

    PubMed

    Nishida, H; Beppu, T; Nakajima, M; Nishinaka, T; Nakatani, H; Ihashi, K; Katsumata, T; Kitamura, M; Aomi, S; Endo, M

    1995-07-01

    To improve the ease of driving a centrifugal pump that is afterload dependent, we have developed an automatic flow control system for the Terumo Capiox centrifugal pump system. This system consists of an autoflow cruise control system with a safety cutoff. The Capiox Pump Console 3000 was controlled by a personal computer through a serial communication line. In the usual manual mode, the motor speed knob works as a pump speed control, and in the autoflow mode, the same knob works as a blood flow rate control. After selecting and obtaining the desired flow rate, the mode was changed from manual to autoflow mode. In the autoflow mode, the computer compares the desired flow rate with the actual flow measured by an ultrasonic Doppler flowmeter and adjusts the motor rotational speed accordingly. During both in vivo and in vitro testing, this autoflow mode was able to return the changed flow that was disrupted by either clamping and declamping of the tubing or by the bolus injection of a vasomotor drug to the selected flow rate within 10 s without any significant fluctuation. In conclusion, the newly developed computer controlled autoflow system was able to produce a reliable and effective flow regulation for a centrifugal pump.

  15. Hemodynamics during Rotary Blood Pump support with speed synchronization in heart failure condition: A modelling study.

    PubMed

    Htet, Zwe Lin; Aye, Thin Pa Pa; Singhavilai, Thamvarit; Naiyanetr, Phornphop

    2015-01-01

    The aim of this work is to study the hemodynamic changes in the cardiovascular system under different modes of Rotary Blood Pump (RBP) support. Continuous mode (constant pump speed) and co-pulse mode (increased pump speed in systole) are studied. Computer simulation studies have been conducted to evaluate the performances of these two modes under normal and pathological conditions. The pathological heart condition is simulated by reducing the maximum systolic elestance (Emax) in the cardiovascular system model. The model is implemented by using MATLAB Simulink. The pressure-volume loop of different heart conditions (normal heart: 100% of normal contractility, pathological heart: 30% of normal contractility) and the different modes of RBP support (8 krpm and 11 krpm in continuous mode, between 8 krpm and 11 krpm in co-pulse mode) are simulated. The results of this study show the slope of end systolic pressure volume relationship (ESPVR) changes in pathological condition. The reduction of area inside pressure volume loops depend on the increasing level of pump speed. The results indicated systolic aortic pressures in co-pulse mode are higher than in the continuous mode. In normal condition, the value of systolic aortic pressure in co-pulse mode is 113 mmHg and the values of systolic aortic pressures in continuous modes are 109 mmHg (8 k) and 95 mmHg (11 k). In pathological condition, the value of systolic aortic pressure in co pulse mode is 100 mmHg and the values of systolic aortic pressures in continuous modes are 90 mmHg (8 k) and 95 mmHg (11 k). The hemodynamics results of this study are comparable in vivo data, clinical data and other simulation studies. Therefore, this simulation enables hemodynamic studies in patients with end-stage heart failure, and patients under different modes of rotary blood pump support.

  16. In vivo performance of a muscle-powered drive system for implantable blood pumps.

    PubMed

    Trumble, Dennis R; Melvin, David B; Dean, David A; Magovern, James A

    2008-01-01

    A unique biomechanical implant has been developed to convert muscle power into hydraulic energy for the purpose of driving an implanted blood pump. This device, called a muscle energy converter (MEC), is designed to attach to the humeral insertion of the latissimus dorsi (LD) muscle, so that stimulated contractions cause a rotary cam to compress a fluid-filled bellows. Here we report results from the latest in a series of canine implant trials where the MEC was connected to an adjustable pressure load to measure power output and assess long-term function. Full-length (2 cm) actuator strokes were maintained for a period of 1 month with no discernable discomfort to the animal. Load conditions were cycled periodically to measure stroke work capacity and pressure production. The peak driveline pressure recorded in this experiment was 1743 mm Hg. Steady state power generation was measured to 478 +/- 21 mJ/stroke (mean +/- SD) with stroke work levels reaching 785 mJ in one test. Normal left and right ventricular stroke work levels in dogs this size (35 kg) are 700 and 150 mJ, respectively. These data confirm that MEC/LD power levels--maintained in tandem with an appropriate cardiac assist device--are sufficient to provide significant long-term circulatory support. Further testing, however, is still needed to demonstrate the long-term stability of this drive system.

  17. Design analysis and performance assessment of hybrid magnetic bearings for a rotary centrifugal blood pump.

    PubMed

    Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F

    2009-01-01

    A hybrid magnetic bearing system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact bearings to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic bearing system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust bearing. The control position is continuously adjusted based on the electrical energy in the bearing coils, and thus passive magnetic forces carry static thrust loads to minimize the bearing current. Performance of the magnetic bearing system with associated control algorithm was evaluated at different operating conditions. The bearing current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The bearing parameters predicted by the analysis were validated by the experimental data.

  18. Feasibility of an air motor-driven centrifugal blood-pumping system.

    PubMed

    Forbes, S J; Akula, J; Smith, W A

    1996-07-01

    The use of cardiopulmonary bypass (CPB) is extending out of the cardiac surgery operating room into new venues. The long-term goal of this project is the development of a completely disposable temporary-use CPB system that could be economically distributed to all of the units where it might be needed. Centrifugal blood pumps have demonstrated successful and widespread use. However, they are not as widely available as might be desired because they require a large and expensive console. An inexpensive, small, lightweight, disposable unit, in contrast, could be widely distributed for emergency care of patients and would be logistically practical for patient transportation between the presenting institution and a major cardiac care facility equipped for definitive treatment. An air motor might be an approach to such a device. The current research project underway at the University of Akron in conjunction with the Cleveland Clinic Foundation has focused on the following key feasibility issues: air consumption, air motor noise, and sealing the rotating shaft. Prototypes have been constructed from commercially available vane and turbine motors. Early studies have demonstrated favorable results with regard to air consumption and shaft sealing and directions for handling air motor noise.

  19. Preload-based Starling-like control of rotary blood pumps: An in-vitro evaluation.

    PubMed

    Mansouri, Mahdi; Gregory, Shaun D; Salamonsen, Robert F; Lovell, Nigel H; Stevens, Michael C; Pauls, Jo P; Akmeliawati, Rini; Lim, Einly

    2017-01-01

    Due to a shortage of donor hearts, rotary left ventricular assist devices (LVADs) are used to provide mechanical circulatory support. To address the preload insensitivity of the constant speed controller (CSC) used in conventional LVADs, we developed a preload-based Starling-like controller (SLC). The SLC emulates the Starling law of the heart to maintain mean pump flow ([Formula: see text]) with respect to mean left ventricular end diastolic pressure (PLVEDm) as the feedback signal. The SLC and CSC were compared using a mock circulation loop to assess their capacity to increase cardiac output during mild exercise while avoiding ventricular suction (marked by a negative PLVEDm) and maintaining circulatory stability during blood loss and severe reductions in left ventricular contractility (LVC). The root mean squared hemodynamic deviation (RMSHD) metric was used to assess the clinical acceptability of each controller based on pre-defined hemodynamic limits. We also compared the in-silico results from our previously published paper with our in-vitro outcomes. In the exercise simulation, the SLC increased [Formula: see text] by 37%, compared to only 17% with the CSC. During blood loss, the SLC maintained a better safety margin against left ventricular suction with PLVEDm of 2.7 mmHg compared to -0.1 mmHg for CSC. A transition to reduced LVC resulted in decreased mean arterial pressure (MAP) and [Formula: see text] with CSC, whilst the SLC maintained MAP and [Formula: see text]. The results were associated with a much lower RMSHD value with SLC (70.3%) compared to CSC (225.5%), demonstrating improved capacity of the SLC to compensate for the varying cardiac demand during profound circulatory changes. In-vitro and in-silico results demonstrated similar trends to the simulated changes in patient state however the magnitude of hemodynamic changes were different, thus justifying the progression to in-vitro evaluation.

  20. Preload-based Starling-like control of rotary blood pumps: An in-vitro evaluation

    PubMed Central

    Gregory, Shaun D.; Salamonsen, Robert F.; Lovell, Nigel H.; Stevens, Michael C.; Pauls, Jo P.; Akmeliawati, Rini; Lim, Einly

    2017-01-01

    Due to a shortage of donor hearts, rotary left ventricular assist devices (LVADs) are used to provide mechanical circulatory support. To address the preload insensitivity of the constant speed controller (CSC) used in conventional LVADs, we developed a preload-based Starling-like controller (SLC). The SLC emulates the Starling law of the heart to maintain mean pump flow (QP¯) with respect to mean left ventricular end diastolic pressure (PLVEDm) as the feedback signal. The SLC and CSC were compared using a mock circulation loop to assess their capacity to increase cardiac output during mild exercise while avoiding ventricular suction (marked by a negative PLVEDm) and maintaining circulatory stability during blood loss and severe reductions in left ventricular contractility (LVC). The root mean squared hemodynamic deviation (RMSHD) metric was used to assess the clinical acceptability of each controller based on pre-defined hemodynamic limits. We also compared the in-silico results from our previously published paper with our in-vitro outcomes. In the exercise simulation, the SLC increased QP¯ by 37%, compared to only 17% with the CSC. During blood loss, the SLC maintained a better safety margin against left ventricular suction with PLVEDm of 2.7 mmHg compared to -0.1 mmHg for CSC. A transition to reduced LVC resulted in decreased mean arterial pressure (MAP) and QP¯ with CSC, whilst the SLC maintained MAP and QP¯. The results were associated with a much lower RMSHD value with SLC (70.3%) compared to CSC (225.5%), demonstrating improved capacity of the SLC to compensate for the varying cardiac demand during profound circulatory changes. In-vitro and in-silico results demonstrated similar trends to the simulated changes in patient state however the magnitude of hemodynamic changes were different, thus justifying the progression to in-vitro evaluation. PMID:28212401

  1. Fresh whole blood versus reconstituted blood for pump priming in heart surgery in infants.

    PubMed

    Mou, Steven S; Giroir, Brett P; Molitor-Kirsch, Erica A; Leonard, Steven R; Nikaidoh, Hisashi; Nizzi, Frank; Town, Deborah A; Roy, Lonnie C; Scott, William; Stromberg, Daniel

    2004-10-14

    In an attempt to reduce the coagulopathic and inflammatory responses seen after cardiopulmonary bypass, the use of fresh whole blood during heart operations has become the standard of care for neonates and infants at many institutions. We compared the use of fresh whole blood with the use of a combination of packed red cells and fresh-frozen plasma (reconstituted blood) for priming of the cardiopulmonary bypass circuit. We conducted a single-center, randomized, double-blind, controlled trial involving children less than one year of age who underwent open-heart surgery. Patients were assigned to receive either fresh whole blood that had been collected not more than 48 hours previously (96 patients) or reconstituted blood (104 patients) for bypass-circuit priming. Clinical outcomes and serologic measures of systemic inflammation and myocardial injury were compared between the groups. The group that received reconstituted blood had a shorter stay in the intensive care unit than the group that received fresh whole blood (70.5 hours vs. 97.0 hours, P=0.04). The group that received reconstituted blood also had a smaller cumulative fluid balance at 48 hours (-6.9 ml per kilogram of body weight vs. 28.8 ml per kilogram, P=0.003). Early postoperative chest-tube output, blood-product transfusion requirements, and levels of serum mediators of inflammation and cardiac troponin I were similar in the two groups. The use of fresh whole blood for cardiopulmonary bypass priming has no advantage over the use of a combination of packed red cells and fresh-frozen plasma during surgery for congenital heart disease. Moreover, circuit priming with fresh whole blood is associated with an increased length of stay in the intensive care unit and increased perioperative fluid overload. Copyright 2004 Massachusetts Medical Society.

  2. Development of an implantable oxygenator with cross-flow pump.

    PubMed

    Asakawa, Yuichi; Funakubo, Akio; Fukunaga, Kazuyoshi; Taga, Ichiro; Higami, Tetsuya; Kawamura, Tsuyoshi; Fukui, Yasuhiro

    2006-01-01

    Thrombogenicity, a problem with long-term artificial lungs, is caused by blood-biomaterial interactions and is made worse by nonuniform flow, which also causes decreased gas exchange. To overcome these obstacles, we changed the inlet and added a uniform flow pump to our previous oxygenator design. Conventional membrane oxygenators have a (1/2)-inch port for the inlet of blood. These port structures make it difficult for the blood to flow uniformly in the oxygenator. In addition, the complex blood flow patterns that occur in the oxygenator, including turbulence and stagnation, lead to thrombogenicity. A cross-flow pump (CFP) can result in uniform blood flow to the inlet side of an oxygenator. In this study, we evaluated the usefulness of an integrated oxygenator with a fiber bundle porosity of 0.6 and a membrane surface area of 1.3 m2. The inlet part of the oxygenator is improved and better fits the outlet of the CFP. Each of the three models of the improved oxygenator has a different inlet taper angle. The computational fluid dynamics analysis showed that, compared with the original design, uniform flow of the integrated oxygenator improved by 88.8% at the hollow fiber membrane. With the integrated oxygenator, O2 transfer increased by an average of 20.8%, and CO2 transfer increased by an average of 35.5%. The results of our experiments suggest that the CFP, which produces a wide, uniform flow to the oxygenator, is effective in attaining high gas exchange performance.

  3. One thousand dollar assist heart pump for patients from developing countries.

    PubMed

    Qian, Kun-Xi

    2007-06-28

    In spite of continuous improvements in device design and applications, the profound use of heart pump has been limited because of its high price. The available clinically applied heart pump costs mostly about 100 thousands US Dollars. The author has since long tried to develop a heart pump costing only 1000 Dollars for recovery or bridge to heart transplantation therapies. The device is a radially driven centrifugal pump with a brush-less DC motor and a streamlined impeller. Its bearing is rolling bearing using 4 to 6 needles, manufactured by special wear-proof polythene with super-high-molecular weight, thus the service life achieves more than 10 years. To avoid thrombus formation, a special purge system is introduced to the bearing, allowing the saline with heparin to be infused through the bearing into the pump. The bearing, therefore, keeps working in the saline, and absolutely no thrombus will be formed along the bearing. Animal experiments demonstrated that a 30 mL fluid infusion per hour is enough to prevent thrombus formation. With these improvements, the impeller pump has continuously run for 14 months in the laboratory, and no bearing wear can be measured. The device, weighing 150 g, is fully implantable, consumes approximately 9.6 W, delivers a 9Lmin-1 blood flow against a 120 mmHg mean pressure, and reaches a highest total efficiency of 24.7% for the motor (including the controller) and the pump. The device has been used in animal experiments together with an American artificial lung for more than one month in the University of Texas and also in human trials in the Taiwan University.

  4. One Thousand Dollar Assist Heart Pump for Patients from Developing Countries

    PubMed Central

    Qian, Kun-xi

    2007-01-01

    In spite of continuous improvements in device design and applications, the profound use of heart pump has been limited because of its high price. The available clinically applied heart pump costs mostly about 100 thousands US Dollars. The author has since long tried to develop a heart pump costing only 1000 Dollars for recovery or bridge to heart transplantation therapies. The device is a radially driven centrifugal pump with a brush-less DC motor and a streamlined impeller. Its bearing is rolling bearing using 4 to 6 needles, manufactured by special wear-proof polythene with super-high-molecular weight, thus the service life achieves more than 10 years. To avoid thrombus formation, a special purge system is introduced to the bearing, allowing the saline with heparin to be infused through the bearing into the pump. The bearing, therefore, keeps working in the saline, and absolutely no thrombus will be formed along the bearing. Animal experiments demonstrated that a 30 mL fluid infusion per hour is enough to prevent thrombus formation. With these improvements, the impeller pump has continuously run for 14 months in the laboratory, and no bearing wear can be measured. The device, weighing 150 g, is fully implantable, consumes approximately 9.6 W, delivers a 9Lmin-1 blood flow against a 120 mmHg mean pressure, and reaches a highest total efficiency of 24.7% for the motor (including the controller) and the pump. The device has been used in animal experiments together with an American artificial lung for more than one month in the University of Texas and also in human trials in the Taiwan University. PMID:19662122

  5. Development of a mercury electromagnetic centrifugal pump for the SNAP-8 refractory boiler development program

    NASA Technical Reports Server (NTRS)

    Fuller, R. A.; Schnacke, A. W.

    1974-01-01

    An electromagnetic pump, in which pressure is developed in mercury because of the interaction of the magnetic field and current which flows as a result of the voltage induced in the mercury contained in the pump duct, was developed for the SNAP-8 refractory boiler test facility. Pump performance results are presented for ten duct configurations and two stator sizes. These test results were used to design and fabricate a pump which met the SNAP-8 criteria of 530 psi developed pressure at 12,500 lb/hr. The pump operated continuously for over 13,000 hours without failure or performance degradation. Included in this report are descriptions of the experimental equipment, measurement techniques, all experimental data, and an analysis of the electrical losses in the pump.

  6. A new technique to control brushless motor for blood pump application.

    PubMed

    Fonseca, Jeison; Andrade, Aron; Nicolosi, Denys E C; Biscegli, José F; Legendre, Daniel; Bock, Eduardo; Lucchi, Júlio César

    2008-04-01

    This article presents a back-electromotive force (BEMF)-based technique of detection for sensorless brushless direct current motor (BLDCM) drivers. The BLDCM has been chosen as the energy converter in rotary or pulsatile blood pumps that use electrical motors for pumping. However, in order to operate properly, the BLDCM driver needs to know the shaft position. Usually, that information is obtained through a set of Hall sensors assembled close to the rotor and connected to the electronic controller by wires. Sometimes, a large distance between the motor and controller makes the system susceptible to interference on the sensor signal because of winding current switching. Thus, the goal of the sensorless technique presented in this study is to avoid this problem. First, the operation of BLDCM was evaluated on the electronic simulator PSpice. Then, a BEMF detector circuitry was assembled in our laboratories. For the tests, a sensor-dependent system was assembled where the direct comparison between the Hall sensors signals and the detected signals was performed. The obtained results showed that the output sensorless detector signals are very similar to the Hall signals at speeds of more than 2500 rpm. Therefore, the sensorless technique is recommended as a responsible or redundant system to be used in rotary blood pumps.

  7. Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA

    PubMed Central

    Cheng, Shanbao; Olles, Mark W.; Burger, Aaron F.; Day, Steven W.

    2011-01-01

    In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negative radial stiffness partially compensated for by increased current stiffness. Accordingly, the performance of the maglev axial flow blood pump with the optimized HMBs was improved: the maximum pump speed was increased from 6000 rpm to 9000 rpm (50%). The radial, axial and current stiffness of the HMB was found to be linear at nominal operational position from both 3-D FEA and empirical measurements. Stiffness values determined by FEA and empirical measurements agreed well with one another. The magnetic flux density distribution and flux loop of the HMB were also visualized via 3-D FEA which confirms the designers’ initial assumption about the function of this HMB. PMID:22065892

  8. Optimization of a Hybrid Magnetic Bearing for a Magnetically Levitated Blood Pump via 3-D FEA.

    PubMed

    Cheng, Shanbao; Olles, Mark W; Burger, Aaron F; Day, Steven W

    2011-10-01

    In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original design, the optimized HMB had twice the axial stiffness with the resulting increase of negative radial stiffness partially compensated for by increased current stiffness. Accordingly, the performance of the maglev axial flow blood pump with the optimized HMBs was improved: the maximum pump speed was increased from 6000 rpm to 9000 rpm (50%). The radial, axial and current stiffness of the HMB was found to be linear at nominal operational position from both 3-D FEA and empirical measurements. Stiffness values determined by FEA and empirical measurements agreed well with one another. The magnetic flux density distribution and flux loop of the HMB were also visualized via 3-D FEA which confirms the designers' initial assumption about the function of this HMB.

  9. A novel integrated rotor of axial blood flow pump designed with computational fluid dynamics.

    PubMed

    Zhang, Yan; Xue, Song; Gui, Xing-min; Sun, Han-song; Zhang, Hao; Zhu, Xiao-dong; Hu, Sheng-Shou

    2007-07-01

    Due to the smaller size, smaller artificial surface, and higher efficiency, axial blood pumps have been widely applied in clinic in recent years. However, because of its high rotor speed, axial flow pump always has a high risk for hemolysis, which the red blood cells devastated by the shearing of tip clearance flow. We reported a novel design with the integrated blade-shroud structure that was expected to solve this problem by abolishing the radial clearance between blade and casing designed with the techniques of computational fluid dynamics (CFD). However, the numerical simulation result of the newly designed structure showed an unexpected backflow (where flow velocity is reverse of the main flow direction) at the blade tip. In order to eliminate this backflow, four flow passes were attempted, and the expansion angles (which reflect the radial amplification of the flow pass, on the meridional section, and should be defined as the angle between the center line of the flow pass and the axial direction) of the blades of the integrated rotor are 0 degrees, 8 degrees, 15 degrees, and 20 degrees, respectively. In the CFD result, it could be easily found as the expansion angles increased, the backflow was restrained gradually, and was eliminated at last. After numerous "cut and try" circles, the pump model was finally optimized. The numerical simulation of this model also showed a stable hydraulic characteristic.

  10. The Aachen MiniHLM--a miniaturized heart-lung machine for neonates with an integrated rotary blood pump.

    PubMed

    Arens, Jutta; Schnoering, Heike; Pfennig, Michael; Mager, Ilona; Vázquez-Jiménez, Jaime F; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2010-09-01

    The operation of congenital heart defects in neonates often requires the use of heart-lung machines (HLMs) to provide perfusion and oxygenation. This is prevalently followed by serious complications inter alia caused by hemodilution and extrinsic blood contact surfaces. Thus, one goal of developing a HLM for neonates is the reduction of priming volume and contact surface. The currently available systems offer reasonable priming volumes for oxygenators, reservoirs, etc. However, the necessary tubing system contains the highest volumes within the whole system. This is due to the use of roller pumps; hence, the resulting placement of the complete HLM is between 1 and 2 m away from the operating table due to connective tubing between the components. Therefore, we pursued a novel approach for a miniaturized HLM (MiniHLM) by integrating all major system components in one single device. In particular, the MiniHLM is a HLM with the rotary blood pump centrically integrated into the oxygenator and a heat exchanger integrated into the cardiotomy reservoir which is directly connected to the pump inlet. Thus, tubing is only necessary between the patient and MiniHLM. A total priming volume of 102 mL (including arterial filter and a/v line) could be achieved. To validate the overall concept and the specific design we conducted several in vitro and in vivo test series. All tests confirm the novel concept of the MiniHLM. Its low priming volume and blood contact surface may significantly reduce known complications related to cardiopulmonary bypass in neonates (e.g., inflammatory reaction and capillary leak syndrome).

  11. Development of blood extraction system designed by female mosquito's blood sampling mechanism for bio-MEMS

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Kazuyoshi; Nakanishi, Naoyuki; Nakamachi, Eiji

    2005-02-01

    A compact and wearable wristwatch type Bio-MEMS such as a health monitoring system (HMS) to detect blood sugar level for diabetic patient, was newly developed. The HMS consists of (1) a indentation unit with a microneedle to generate the skin penetration force using a shape memory alloy(SMA) actuator, (2) a pumping unit using a bimorph PZT piezoelectric actuator to extract the blood and (3) a gold (Au) electrode as a biosensor immobilized GOx and attached to the gate electrode of MOSFET to detect the amount of Glucose in extracted blood. GOx was immobilized on a self assembled spacer combined with an Au electrode by the cross-link method using BSA as an additional bonding material. The device can extract blood in a few microliter through a painless microneedle with the negative pressure by deflection of the bimorph PZT piezoelectric actuator produced in the blood chamber, by the similar way the female mosquito extracts human blood with muscle motion to flex or relax. The performances of the liquid sampling ability of the pumping unit through a microneedle (3.8mm length, 100μm internal diameter) using the bimorph PZT piezoelectric microactuator were measured. The blood extraction micro device could extract human blood at the speed of 2μl/min, and it is enough volume to measure a glucose level, compared to the amount of commercial based glucose level monitor. The electrode embedded in the blood extraction device chamber could detect electrons generated by the hydrolysis of hydrogen peroxide produced by the reaction between GOx and glucose in a few microliter extracted blood, using the constant electric current measurement system of the MOSFET type hybrid biosensor. The output voltage for the glucose diluted in the chamber was increased lineally with increase of the glucose concentration.

  12. The cool seal system: a practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps.

    PubMed

    Yamazaki, K; Mori, T; Tomioka, J; Litwak, P; Antaki, J F; Tagusari, O; Koyanagi, H; Griffith, B P; Kormos, R L

    1997-01-01

    A critical issue facing the development of an implantable, rotary blood pump is the maintenance of an effective seal at the rotating shaft. Mechanical seals are the most versatile type of seal in wide industrial applications. However, in a rotary blood pump, typical seal life is much shorter than required for chronic support. Seal failure is related to adhesion and aggregation of heat denatured blood proteins that diffuse into the lubricating film between seal faces. Among the blood proteins, fibrinogen plays an important role due to its strong propensity for adhesion and low transition temperature (approximately 50 degrees C). Once exposed to temperature exceeding 50 degrees C, fibrinogen molecules fuse together by multi-attachment between heat denatured D-domains. This quasi-polymerized fibrin increases the frictional heat, which proliferates the process into seal failure. If the temperature of the seal faces is maintained well below 50 degrees C, a mechanical seal would not fail in blood. Based on this "Cool-Seal" concept, we developed a miniature mechanical seal made of highly thermally conductive material (SiC), combined with a recirculating purge system. A large supply of purge fluid is recirculated behind the seal face to augment convective heat transfer to maintain the seal temperature below 40 degrees C. It also cools all heat generating pump parts (motor coil, bearing, seal). The purge consumption has been optimized to virtually nil (< 0.5 cc/day). An ultrafiltration unit integrated in the recirculating purge system continuously purifies and sterilizes the purge fluid for more than 5 months without filter change. The seal system has now been incorporated into our intraventricular axial flow blood pump (IVAP) and newly designed centrifugal pump. Ongoing in vivo evaluation of these systems has demonstrated good seal integrity for more than 160 days. The Cool-Seal system can be applied to any type of rotary blood pump (axial, diagonal, centrifugal, etc.) and

  13. Computational fluid dynamics prediction of blood damage in a centrifugal pump.

    PubMed

    Song, Xinwei; Throckmorton, Amy L; Wood, Houston G; Antaki, James F; Olsen, Don B

    2003-10-01

    This study explores a quantitative evaluation of blood damage that occurs in a continuous flow left ventricular assist device due to fluid stress. Computational fluid dynamics (CFD) analysis is used to track the shear stress history of 388 particle streaklines. The accumulation of shear and exposure time is integrated along the streaklines to evaluate the levels of blood trauma. This analysis, which includes viscous and turbulent stresses, provides a statistical estimate of possible damage to cells flowing through the pump. In vitro normalized index of hemolysis values for clinically available ventricular assist devices were compared to our damage indices. This allowed for an order of magnitude comparison between our estimations and experimentally measured hemolysis levels, which resulted in a reasonable correlation. This work ultimately demonstrates that CFD is a convenient and effective approach to analyze the Lagranian behavior of blood in a heart assist device.

  14. Blood pressure regulation X: what happens when the muscle pump is lost? Post-exercise hypotension and syncope.

    PubMed

    Halliwill, John R; Sieck, Dylan C; Romero, Steven A; Buck, Tahisha M; Ely, Matthew R

    2014-03-01

    Syncope which occurs suddenly in the setting of recovery from exercise, known as post-exercise syncope, represents a failure of integrative physiology during recovery from exercise. We estimate that between 50 and 80% of healthy individuals will develop pre-syncopal signs and symptoms if subjected to a 15-min head-up tilt following exercise. Post-exercise syncope is most often neurally mediated syncope during recovery from exercise, with a combination of factors associated with post-exercise hypotension and loss of the muscle pump contributing to the onset of the event. One can consider the initiating reduction in blood pressure as the tip of the proverbial iceberg. What is needed is a clear model of what lies under the surface; a model that puts the observational variations in context and provides a rational framework for developing strategic physical or pharmacological countermeasures to ultimately protect cerebral perfusion and avert loss of consciousness. This review summarizes the current mechanistic understanding of post-exercise syncope and attempts to categorize the variation of the physiological processes that arise in multiple exercise settings. Newer investigations into the basic integrative physiology of recovery from exercise provide insight into the mechanisms and potential interventions that could be developed as countermeasures against post-exercise syncope. While physical counter maneuvers designed to engage the muscle pump and augment venous return are often found to be beneficial in preventing a significant drop in blood pressure after exercise, countermeasures that target the respiratory pump and pharmacological countermeasures based on the involvement of histamine receptors show promise.

  15. Blood Pressure-Lowering Effect of Orally Ingested Nitrite Is Abolished by a Proton Pump Inhibitor.

    PubMed

    Montenegro, Marcelo F; Sundqvist, Michaela L; Larsen, Filip J; Zhuge, Zhengbing; Carlström, Mattias; Weitzberg, Eddie; Lundberg, Jon O

    2017-01-01

    Inorganic nitrate and nitrite from dietary and endogenous sources are metabolized to NO and other bioactive nitrogen oxides that affect blood pressure. The mechanisms for nitrite bioactivation are unclear, but recent studies in rodents suggest that gastric acidity may influence the systemic effects of this anion. In a randomized, double-blind, placebo-controlled crossover study, we tested the effects of a proton pump inhibitor on the acute cardiovascular effects of nitrite. Fifteen healthy nonsmoking, normotensive subjects, aged 19 to 39 years, were pretreated with placebo or esomeprazole (3×40 mg) before ingesting sodium nitrite (0.3 mg kg(-1)), followed by blood pressure monitoring. Nitrite reduced systolic blood pressure by a maximum of 6±1.3 mm Hg when taken after placebo, whereas pretreatment with esomeprazole blunted this effect. Peak plasma nitrite, nitrate, and nitroso species levels after nitrite ingestion were similar in both interventions. In 8 healthy volunteers, we then infused increasing doses of sodium nitrite (1, 10, and 30 nmol kg(-1) min(-1)) intravenously. Interestingly, although plasma nitrite peaked at similar levels as with orally ingested nitrite (≈1.8 µmol/L), no changes in blood pressure were observed. In rodents, esomeprazole did not affect the blood pressure response to the NO donor, DEA NONOate, or vascular relaxation to nitroprusside and acetylcholine, demonstrating an intact downstream NO-signaling pathway. We conclude that the acute blood pressure-lowering effect of nitrite requires an acidic gastric environment. Future studies will reveal if the cardiovascular complications associated with the use of proton pump inhibitors are linked to interference with the nitrate-nitrite-NO pathway. © 2016 American Heart Association, Inc.

  16. Left ventricular volume unloading with axial and centrifugal rotary blood pumps.

    PubMed

    Giridharan, Guruprasad A; Koenig, Steven C; Soucy, Kevin G; Choi, Young; Pirbodaghi, Tohid; Bartoli, Carlo R; Monreal, Gretel; Sobieski, Michael A; Schumer, Erin; Cheng, Allen; Slaughter, Mark S

    2015-01-01

    Axial (AX) and centrifugal (CFG) rotary blood pumps have gained clinical acceptance for the treatment of advanced heart failure. Differences between AX and CFG designs and mechanism of blood flow delivery may offer clinical advantages. In this study, pump characteristics, and acute physiologic responses during support with AX (HeartMate II) and CFG (HVAD) left ventricular assist devices (LVAD) were investigated in mock loop and chronic ischemic heart failure bovine models. In the mock loop model, pump performance was characterized over a range of pump speeds (HeartMate II: 7,000-11,000 rpm, HVAD: 2,000-3,600 rpm) and fluid viscosities (2.7 cP, 3.2 cP, 3.7 cP). In the ischemic heart failure bovine model, hemodynamics, echocardiography, and end-organ perfusion were investigated. CFG LVAD had a flatter HQ curve, required less power, and had a more linear flow estimation relation than AX LVAD. The flow estimation error for the AX LVAD (±0.9 L/min at 2.7 cP, ±0.7 L/min at 3.2 cP, ±0.8 L/min at 3.7 cP) was higher than the CFG LVAD (±0.5 L/min at 2.7 cP, ±0.2 L/min at 3.2 cP, ±0.5 L/min at 3.7 cP). No differences in acute hemodynamics, echocardiography, or end-organ perfusion between AX and CFG LVAD over a wide range of support were statistically discernible. These findings suggest no pronounced acute differences in LV volume unloading between AX and CFG LVAD.

  17. The Effects of Ambulatory Accelerations on the Stability of a Magnetically Suspended Impeller for an Implantable Blood Pump.

    PubMed

    Paul, Gordon; Rezaienia, Mohammed Amin; Rahideh, Akbar; Munjiza, Ante; Korakianitis, Theodosios

    2016-09-01

    This article describes the effects of ambulatory accelerations on the stability of a magnetically suspended impeller for use in implantable blood pumps. A magnetic suspension system is developed to control the radial position of a magnetic impeller using coils in the pump casing. The magnitude and periodicity of ambulatory accelerations at the torso are measured. A test rig is then designed to apply appropriate accelerations to the suspension system. Accelerations from 0 to 1 g are applied to the suspended impeller with ambulatory periodicity while the radial position of the impeller and power consumption of the suspension system are monitored. The test is carried out with the impeller suspended in air, water, and a glycerol solution to simulate the viscosity of blood. A model is developed to investigate the effects of the radial magnetic suspension system and fluid damping during ambulatory accelerations. The suspension system reduces the average displacement of the impeller suspended in aqueous solutions within its casing to 100 µm with a power consumption of below 2 W during higher magnitude ambulatory accelerations (RMS magnitude 0.3 g). The damping effect of the fluid is also examined and it is shown that buoyancy, rather than drag, is the primary cause of the damping at the low displacement oscillations that occur during the application of ambulatory accelerations to such a suspension system.

  18. Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

    PubMed

    Bock, Eduardo; Antunes, Pedro; Leao, Tarcisio; Uebelhart, Beatriz; Fonseca, Jeison; Leme, Juliana; Utiyama, Bruno; da Silva, Cibele; Cavalheiro, Andre; Filho, Diolino Santos; Dinkhuysen, Jarbas; Biscegli, Jose; Andrade, Aron; Arruda, Celso

    2011-05-01

    An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

  19. A method for control of an implantable rotary blood pump for heart failure patients using noninvasive measurements.

    PubMed

    Lim, Einly; Alomari, Abdul-Hakeem H; Savkin, Andrey V; Dokos, Socrates; Fraser, John F; Timms, Daniel L; Mason, David G; Lovell, Nigel H

    2011-08-01

    We propose a deadbeat controller for the control of pulsatile pump flow (Q(p) ) in an implantable rotary blood pump (IRBP). Noninvasive measurements of pump speed and current are used as inputs to a dynamical model of Q(p) estimation, previously developed and verified in our laboratory. The controller was tested using a lumped parameter model of the cardiovascular system (CVS), in combination with the stable dynamical models of Q(p) and differential pressure (head) estimation for the IRBP. The control algorithm was tested with both constant and sinusoidal reference Q(p) as input to the CVS model. Results showed that the controller was able to track the reference input with minimal error in the presence of model uncertainty. Furthermore, Q(p) was shown to settle to the desired reference value within a finite number of sampling periods. Our results also indicated that counterpulsation yields the minimum left ventricular stroke work, left ventricular end diastolic volume, and aortic pulse pressure, without significantly affecting mean cardiac output and aortic pressure.

  20. A control system for rotary blood pumps based on suction detection.

    PubMed

    Ferreira, Antonio; Boston, J Robert; Antaki, James F

    2009-03-01

    A control system for rotary ventricular assist devices was developed to automatically regulate the pumping speed of the device to avoid ventricular suction. The control system comprises a suction detector and a fuzzy logic controller (FLC). The suction detector can correctly classify pump flow patterns, using a discriminant analysis (DA) model that combines several indices derived from the pump flow signal, to classify the pump status as one of the following: no suction (NS), moderate suction (MS), and severe suction (SS). The discriminant scores, which are the output of the suction detector, were used as inputs to the FLC. Based on this information, the controller updates pump speed, providing adequate flow and pressure perfusion to the patient. The performance of the control system was tested in simulations over a wide range of physiological conditions, including hypertension, exercise, and strenuous exercising for healthy, sick, and very sick hearts, using a lumped parameter model of the circulatory system coupled with a left ventricular assist device. The controller was able to maintain cardiac output and mean arterial pressure within acceptable physiologic ranges, while avoiding suction, demonstrating the feasibility of the proposed control system.

  1. Bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Kosaka, Ryo; Yoshida, Fumihiko; Nishida, Masahiro; Maruyama, Osamu; Kawaguchi, Yasuo; Yamane, Takashi

    2015-01-01

    The purpose of the present study is to investigate a bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump to realize a blood pump with a low hemolysis level. The impeller levitates axially by balancing a gravitational force, buoyancy, a magnetic force, and hydrodynamic forces on the top and bottom sides of the impeller. To adjust the levitation position of the impeller, the balance of acting forces on the impeller was adjusted by changing the shroud area on the bottom impeller. Three pumps having various shroud area were prepared as tested models: 817 mm(2) (HH-S), 875 mm(2) (HH-M) and 931 mm(2) (HH-L). First, for evaluating the bearing gap adjustment, the bearing gap was estimated by calculating a balancing position of the acting forces on the impeller. We actually measured the gravitational force, buoyancy and the magnetic force, and numerically analyzed hydrodynamic forces on the top and bottom sides of the impeller. Second, to verify accuracy of the estimated bearing gap, the measurement test of the bearing gap was performed. Finally, an in-vitro hemolysis test was performed to evaluate a hemolysis level of the pump. As a result, bottom bearing gaps were estimated as 40 μm (HH-S), 60 μm (HH-M) and 238 μm (HH-L). In the measurement test, bottom bearing gaps were measured as 63 μm (HH-S), 219 μm (HH-M), and 231 μm (HH-L). The estimated bearing gaps had positively correlated with the measured bearing gaps in relation to the shroud area on the impeller. In the hemolysis test, hemolysis level in every model was almost equivalent to that of BPX-80, when the bearing gap was adjusted greater than 60 μm. We could adjust the bearing gap by changing the shroud area on the impeller for improvement of levitation performance to realize a blood pump with a low hemolysis level.

  2. New generation extracorporeal membrane oxygenation with MedTech Mag-Lev, a single-use, magnetically levitated, centrifugal blood pump: preclinical evaluation in calves.

    PubMed

    Fujiwara, Tatsuki; Nagaoka, Eiki; Watanabe, Taiju; Miyagi, Naoto; Kitao, Takashi; Sakota, Daisuke; Mamiya, Taichi; Shinshi, Tadahiko; Arai, Hirokuni; Takatani, Setsuo

    2013-05-01

    We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, MedTech Mag-Lev, in a 3-week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio-Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH-R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio-Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200-240 s. All the MedTech ECMO calves completed the study duration. However, the Bio-Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the MedTech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO2 of the oxygenator outlet was higher than 400 mm Hg with the PCO2 below 45 mm Hg. Hemolysis and thrombus were not seen in the MedTech ECMO circuits (plasma-free hemoglobin [PFH] < 5 mg/dL), while severe hemolysis (PFH > 20 mg/dL) and large thrombus were observed in the Bio-Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three-week cardiopulmonary support was performed successfully with the MedTech ECMO without circuit exchanges. The MedTech Mag-Lev could help extend the durability of ECMO circuits by the improved biocompatible performances.

  3. Further development of high-power pump laser diodes

    NASA Astrophysics Data System (ADS)

    Schmidt, Berthold; Lichtenstein, Norbert; Sverdlov, Boris; Matuschek, Nicolai; Mohrdiek, Stefan; Pliska, Tomas; Mueller, Juergen; Pawlik, Susanne; Arlt, Sebastian; Pfeiffer, Hans-Ulrich; Fily, Arnaud; Harder, Christoph

    2003-12-01

    AlGaAs/InGaAs based high power pump laser diodes with wavelength of around 980 nm are key products within erbium doped fiber amplifiers (EDFA) for today's long haul and metro-communication networks, whereas InGaAsP/InP based laser diodes with 14xx nm emission wavelength are relevant for advanced, but not yet widely-used Raman amplifiers. Due to the changing industrial environment cost reduction becomes a crucial factor in the development of new, pump modules. Therefore, pump laser chips were aggressively optimized in terms of power conversion and thermal stability, which allows operation without active cooling at temperatures exceeding 70°C. In addition our submarine-reliable single mode technology was extended to high power multi-mode laser diodes. These light sources can be used in the field of optical amplifiers as well as for medical, printing and industrial applications. Improvements of pump laser diodes in terms of power conversion efficiency, fiber Bragg grating (FBG) locking performance of single mode devices, noise reduction and reliability will be presented.

  4. Dual-Pump CARS Development and Application to Supersonic Combustion

    NASA Technical Reports Server (NTRS)

    Magnotti, Gaetano; Cutler, Andrew D.

    2012-01-01

    A dual-pump Coherent Anti-Stokes Raman Spectroscopy (CARS) instrument has been developed to obtain simultaneous measurements of temperature and absolute mole fractions of N2, O2 and H2 in supersonic combustion and generate databases for validation and development of CFD codes. Issues that compromised previous attempts, such as beam steering and high irradiance perturbation effects, have been alleviated or avoided. Improvements in instrument precision and accuracy have been achieved. An axis-symmetric supersonic combusting coaxial jet facility has been developed to provide a simple, yet suitable flow to CFD modelers. Approximately one million dual-pump CARS single shots have been collected in the supersonic jet for varying values of flight and exit Mach numbers at several locations. Data have been acquired with a H2 co-flow (combustion case) or a N2 co-flow (mixing case). Results are presented and the effects of the compressibility and of the heat release are discussed.

  5. Detection of ventricular suction in an implantable rotary blood pump using support vector machines.

    PubMed

    Wang, Yu; Faragallah, George; Divo, Eduardo; Simaan, Marwan A

    2011-01-01

    A new suction detection algorithm for rotary Left Ventricular Assist Devices (LVAD) is presented. The algorithm is based on a Lagrangian Support Vector Machine (LSVM) model. Six suction indices are derived from the LVAD pump flow signal and form the inputs to the LSVM classifier. The LSVM classifier is trained and tested to classify pump flow patterns into three states: No Suction, Approaching Suction, and Suction. The proposed algorithm has been tested using existing in vivo data. When compared to three existing methods, the proposed algorithm produced superior performance in terms of classification accuracy, stability, and learning speed. The ability of the algorithm to detect suction provides a reliable platform in the development of a pump speed controller that has the capability of avoiding suction.

  6. Development and evaluation of a wearable blood glucose monitor.

    PubMed

    Zamzow, K L; Schmidt, D G; Shults, M C; Updike, S J; Rhodes, R K; von Heimburg, D F; Luebow, J O

    1990-01-01

    Complex operation, prolonged set-up time, reliability problems, high cost, and excessive size limits the use of currently available extracorporeal continuous blood glucose analyzers. A self-calibrating, wearable blood glucose monitor has been developed to overcome these impediments. The wearable blood glucose monitor is a 410 g forearm-mounted instrument with three miniature pumps for blood sampling, calibration, and insulin infusion, and a flow cell containing an enzyme-electrode sensor capable of determining plasma glucose levels accurately and precisely in undiluted whole blood. The unit is connected to a computer controller with graphics display. Venous blood is drawn from a 21 gauge single lumen cannula through the sensor flow cell. A rate determination of glucose is completed in 20 sec and the blood is returned to the arm vein. Heparinized saline wash solution follows. No blood loss or significant systemic heparinization occurs. Cycle time is set from 2 to 5 min. The method is linear to at least 300 mg/dl glucose, independent of hematocrit, and free of interferences from blood constituents at normal venous pO2 with a coefficient of variation of 1-3% between calibrations. The sensor has a service life of at least 3 weeks. This wearable blood glucose monitor, with its high performance sensor, reduced size, and ease of operation, shows promise for evaluating and treating diabetes.

  7. Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.

    PubMed

    Pai, C N; Shinshi, T; Shimokohbe, A

    2010-01-01

    Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

  8. Noninvasive activity-based control of an implantable rotary blood pump: comparative software simulation study.

    PubMed

    Karantonis, Dean M; Lim, Einly; Mason, David G; Salamonsen, Robert F; Ayre, Peter J; Lovell, Nigel H

    2010-02-01

    A control algorithm for an implantable centrifugal rotary blood pump (RBP) based on a noninvasive indicator of the implant recipient's activity level has been proposed and evaluated in a software simulation environment. An activity level index (ALI)-derived from a noninvasive estimate of heart rate and the output of a triaxial accelerometer-forms the noninvasive indicator of metabolic energy expenditure. Pump speed is then varied linearly according to the ALI within a defined range. This ALI-based control module operates within a hierarchical multiobjective framework, which imposes several constraints on the operating region, such as minimum flow and minimum speed amplitude thresholds. Three class IV heart failure (HF) cases of varying severity were simulated under rest and exercise conditions, and a comparison with other popular RBP control strategies was performed. Pump flow increases of 2.54, 1.94, and 1.15 L/min were achieved for the three HF cases, from rest to exercise. Compared with constant speed control, this represents a relative flow change of 30.3, 19.8, and -15.4%, respectively. Simulations of the proposed control algorithm exhibited the effective intervention of each constraint, resulting in an improved flow response and the maintenance of a safe operating condition, compared with other control modes.

  9. Optical Dynamic Analysis of Thrombus Inside a Centrifugal Blood Pump During Extracorporeal Mechanical Circulatory Support in a Porcine Model.

    PubMed

    Fujiwara, Tatsuki; Sakota, Daisuke; Ohuchi, Katsuhiro; Endo, Shu; Tahara, Tomoki; Murashige, Tomotaka; Kosaka, Ryo; Oi, Keiji; Mizuno, Tomohiro; Maruyama, Osamu; Arai, Hirokuni

    2017-03-20

    Complications due to pump thrombus remain the weak point of mechanical circulatory support (MCS), such as the use of a left ventricular assist device (LVAD) or extracorporeal membrane oxygenation, leading to poor outcomes. Hyperspectral imaging (HSI) is an effective imaging method using a hyperspectral (HS) camera, which comprises a spectrophotometer and a charge-coupled device camera to discriminate thrombus from whole blood. Animal experiments were conducted to analyze dynamic imaging of thrombus inside a prototype of a hydrodynamically levitated centrifugal blood pump using an HSI system. Six pigs were divided into a venous circulation group (n = 3) and an arterial circulation group (n = 3). Inflow and outflow cannulae were inserted into the jugular veins in the venous circulation group. The latter simulated an LVAD application. To create thrombogenic conditions, pump flow was maintained at 1 L/min without anticoagulation. An image of the bottom surface of the pump was captured by the HS camera every 4 nm over the wavelength range of 608-752 nm. Real-time dynamic images of the inside of the pump were displayed on the monitor. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment. This imaging system also succeeded in determining the origins of pump thrombus: from inside the pump in two cases, and from outside in four cases. Two main possible sources of pump thrombus originating outside the pump were identified on autopsy: wedge thrombus around the inflow cannula; and string-like thrombus at the junction between the pump inlet and circuit tube. The results of this study from close observation of the changing appearance of pump thrombus may contribute to improvements in the safety of extracorporeal MCS.

  10. Quantification of the secondary flow in a radial coupled centrifugal blood pump based on particle tracking velocimetry.

    PubMed

    Watanabe, Nobuo; Masuda, Takaya; Iida, Tomoya; Kataoka, Hiroyuki; Fujimoto, Tetsuo; Takatani, Setsuo

    2005-01-01

    Secondary flow in the centrifugal blood pump helps to enhance the washout effect and to minimize thrombus formation. On the other hand, it has an adverse effect on pump efficiency. Excessive secondary flow may induce hemolytic effects. Understanding the secondary flow is thus important to the design of a compact, efficient, biocompatible blood pump. This study examined the secondary flow in a radial coupled centrifugal blood pump based on a simple particle tracking velocimetry (PTV) technique. A radial magnetically coupled centrifugal blood pump has a bell-shaped narrow clearance between the impeller inner radius and the pump casing. In order to vary the flow levels through the clearance area, clearance widths of 0.25 mm and 0.50 mm and impeller washout holes with diameters of 0 mm, 2.5 mm, and 4 mm were prepared. A high-speed video camera (2000 frames per second) was used to capture the particle images from which radial flow components were derived. The flow in the space behind the impeller was assumed to be laminar and Couette type. The larger the inner clearance or diameter of washout hole, the greater was the secondary flow rate. Without washout holes, the flow behind the impeller resulted in convection. The radial flow through the washout holes of the impeller was conserved in the radial as well as in the axial direction behind the impeller. The increase in the secondary flow reduced the net pump efficiency. Simple PTV was successful in quantifying the flow in the space behind the impeller. The results verified the hypothesis that the flow behind the impeller was theoretically Couette along the circumferential direction. The convection flow observed behind the impeller agreed with the reports of other researchers. Simple PTV was effective in understanding the fluid dynamics to help improve the compact, efficient, and biocompatible centrifugal blood pump for safe clinical applications.

  11. Dual-Pump CARS Development and Application to Supersonic Combustion

    NASA Astrophysics Data System (ADS)

    Magnotti, Gaetano

    Successful design of hypersonic air-breathing engines requires new computational fluid dynamics (CFD) models for turbulence and turbulence-chemistry interaction in supersonic combustion. Unfortunately, not enough data are available to the modelers to develop and validate their codes, due to difficulties in taking measurements in such a harsh environment. Dual-pump coherent anti-Stokes Raman spectroscopy (CARS) is a non-intrusive, non-linear, laser-based technique that provides temporally and spatially resolved measurements of temperature and absolute mole fractions of N2, O2 and H2 in H2-air flames. A dual-pump CARS instrument has been developed to obtain measurements in supersonic combustion and generate databases for the CFD community. Issues that compromised previous attempts, such as beam steering and high irradiance perturbation effects, have been alleviated or avoided. Improvements in instrument precision and accuracy have been achieved. An axis-symmetric supersonic combusting coaxial jet facility has been developed to provide a simple, yet suitable flow to CFD modelers. The facility provides a central jet of hot "vitiated air" simulating the hot air entering the engine of a hypersonic vehicle flying at Mach numbers between 5 and 7. Three different silicon carbide nozzles, with exit Mach number 1, 1.6 and 2, are used to provide flows with the effects of varying compressibility. H2 co-flow is available in order to generate a supersonic combusting free jet. Dual-pump CARS measurements have been obtained for varying values of flight and exit Mach numbers at several locations. Approximately one million Dual-pump CARS single shots have been collected in the supersonic jet for varying values of flight and exit Mach numbers at several locations. Data have been acquired with a H2 co-flow (combustion case) or a N 2 co-flow (mixing case). Results are presented and the effects of the compressibility and of the heat release are discussed.

  12. LED pumped Nd:YAG laser development program

    NASA Technical Reports Server (NTRS)

    Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.

    1973-01-01

    The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

  13. Metal hydride/chemical heat pump development project

    NASA Astrophysics Data System (ADS)

    Madariaga, H. A.; Rohy, D. A.

    1982-02-01

    A mental hydride heat pump (MHHP) is a chemical heat pump containing two different hydrides and using hydrogen as a working fluid for the storage and/or recovery of thermal energy. It utilizes the heat of reaction of hydrogen with specific metal alloys. The MHHP design can be tailored to provide heating and cooling or temperature upgrading over a wide range of input and ambient temperatures. This system can be used with a variety of heat sources including industrial waste heat, solar energy or a fossil fuel. Temperature as low as 130 F can drive the MHHP when a suitable sink is provided. A project is currently underway to develop this unique heat pump for a specific application. The goals of the project include the development of cost effective hydride containers with high heat transfer and low mass; design and fabrication of a laboratory evaluation model; and design and fabrication of a demonstration unit. Extensive component and system test will provide the data for the design processes.

  14. A novel design of spiral groove bearing in a hydrodynamically levitated centrifugal rotary blood pump.

    PubMed

    Han, Qing; Zou, Jun; Ruan, Xiaodong; Fu, Xin; Yang, Huayong

    2012-08-01

    Good washout is very important in spiral groove bearing (SGB) designs when applied to blood pumps due to the micrometer scales of lubrication films and groove depths. To improve washout, flow rate or leakage through SGBs should be as large as possible. However, this special goal violates conventional SGB designs in which no leakage is desired as the leakage would decrease load-carrying capacity significantly. So, a design concept is formed fulfilling the two goals of high load-carrying capacity and large flow rate: let groove width decrease along flow path and the mating surface of the rotor rotate with a direction facilitating the flow through the grooves. Under this concept, a novel SGB is designed, contrary to conventional ones, with groove width decreasing with increasing spiral radius. This SGB is mounted on the motionless upper plate of our designed centrifugal blood pump, with the mating surface of rotor rotating with a direction facilitating the outward flow. To assess SGB designs, a characteristic plane is originally presented relating to pressure-normalized load-carrying capacity and flow rate. Comparisons between various kinds of SGB designs are made, and computational fluid dynamics (CFD) results are plotted in this characteristic plane from which load/flow performances can be directly read out. CFD and comparison results show that the new designs have superior load/flow characteristics. However, the impact of SGB designs upon hemolysis/thrombus formation is still to be verified according to the concept presented.

  15. Design and numerical evaluation of an axial partial-assist blood pump for Chinese and other heart failure patients.

    PubMed

    Liu, Guang-Mao; Jin, Dong-Hai; Zhou, Jian-Ye; Jiang, Xi-Hang; Sun, Han-Song; Zhang, Yan; Chen, Hai-Bo; Hu, Sheng-Shou; Gui, Xing-Min

    2017-08-02

    A fully implantable axial left ventricular assist device LAP31 was developed for Chinese or other heart failure patients who need partial support. Based on the 5-Lpm total cardiac blood output of Chinese without heart failure disease, the design point of LAP31 was set to a flow rate of 3 Lpm with 100-mmHg pressure head. To achieve the required pressure head and good hemolytic performance, a structure that includes a spindly rotor hub and a diffuser with splitter and cantilevered main blades was developed. Computational fluid dynamics (CFD) was used to analyze the hydraulic and hemodynamic performance of LAP31. Then in vitro hydraulics experiments were conducted. The numerical simulation results show that LAP31 could generate a 1 to 8 Lpm flow rate with a 60.9 to 182.7 mmHg pressure head when the pump was rotating between 9,000 and 12,000 rpm. The average scalar shear stress of the blood pump was 21.7 Pa, and the average exposure time was 71.0 milliseconds. The mean hemolysis index of LAP31 obtained using Heuser's hemolysis model and Giersiepen's model was 0.220% and 3.89 × 10-5% respectively. After adding the splitter blades, the flow separation at the suction surface of the diffuser was reduced. The cantilever structure reduced the tangential velocity from 6.1 to 4.7-1.4 m/s within the blade gap by changing the blade gap from shroud to hub. Subsequently, the blood damage caused by shear stress was reduced. In conclusion, the hydraulic and hemolytic characteristics of the LAP31 are acceptable for partial support.

  16. [Research on magnetic coupling centrifugal blood pump control based on a self-tuning fuzzy PI algorithm].

    PubMed

    Yang, Lei; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Wang, Wei; Zhang, Haibo; Han, Lu; Xu, Liang

    2014-10-01

    The purpose of this paper is to report the research and design of control system of magnetic coupling centrifugal blood pump in our laboratory, and to briefly describe the structure of the magnetic coupling centrifugal blood pump and principles of the body circulation model. The performance of blood pump is not only related to materials and structure, but also depends on the control algorithm. We studied the algorithm about motor current double-loop control for brushless DC motor. In order to make the algorithm adjust parameter change in different situations, we used the self-tuning fuzzy PI control algorithm and gave the details about how to design fuzzy rules. We mainly used Matlab Simulink to simulate the motor control system to test the performance of algorithm, and briefly introduced how to implement these algorithms in hardware system. Finally, by building the platform and conducting experiments, we proved that self-tuning fuzzy PI control algorithm could greatly improve both dynamic and static performance of blood pump and make the motor speed and the blood pump flow stable and adjustable.

  17. Development of the NEDO implantable ventricular assist device with Gyro centrifugal pump.

    PubMed

    Yoshikawa, M; Nonaka, K; Linneweber, J; Kawahito, S; Ohtsuka, G; Nakata, K; Takano, T; Schulte-Eistrup, S; Glueck, J; Schima, H; Wolner, E; Nosé, Y

    2000-06-01

    The Gyro centrifugal pump, PI (permanently implantable) series, is being developed as a totally implantable artificial heart. Our final goal is to establish a "functional TAH," a totally implantable biventricular assist system (BiVAS) with centrifugal pumps. A plastic prototype pump, Gyro PI 601, was evaluated through in vitro and in vivo studies as a single ventricular assist device (VAD). Based upon these results, the pump head material was converted to a titanium alloy, and the actuator was modified. These titanium Gyro pumps, PI 700 series, also were subjected to in vitro and in vivo studies. The Gyro PI 601 and PI 700 series have the same inner dimensions and characteristics, such as the eccentric inlet port, double pivot bearing system, secondary vane, and magnet coupling system; however, the material of the PI 700 is different from the PI 601. The Gyro PI series is driven by the Vienna DC brushless motor actuator. The inlet cannula of the right ventricular assist system (RVAS) specially made for this system consists of 2 parts: a hat-shaped silicone tip biolized with gelatin and an angled wire reinforced tube made of polyvinylchloride. The pump-actuator package was implanted into 8 calves in the preperitoneal space, bypassing from the left ventricle apex to the descending aorta for the left ventricular assist system (LVAS) and bypassing the right ventricle to the main pulmonary artery for the RVAS. According to the PI 601 feasibility protocol, 2 LVAS cases were terminated after 2 weeks, and 1 LVAS case and 1 RVAS were terminated after 1 month. The PI 700 series was implanted into 4 cases: 3 LVAS cases survived for a long term, 2 of them over 200 days (72-283 days), and 1 RVAS case survived for 1 month and was terminated according to the protocol for a short-term antithrombogenic screening and system feasibility study. Regarding power consumption, the plastic pump cases demonstrated from 6.2 to 12.1 W as LVAS and 7.3 W as RVAS, the titanium pump cases showed

  18. Development of a photo-voltaic pumping system using a brushless D.C. motor and helical rotor pump

    SciTech Connect

    Langridge, D.; Lawrance, W.; Wichert, B.

    1996-12-31

    A PV pumping system based on a brushless d.c. motor and helical rotor pump has been designed, simulated and a prototype constructed. The paper describes the operation of the system and the development of component models for the array, the brushless d.c. motor and helical rotor pump. Simulation results and subsequent test results for the complete system are included. Efficiencies of between 30 and 50% for the system (excluding the array) have been achieved over a range of loads and operating conditions for 4 x 1 and 4 x 2 array configurations. 9 refs., 10 figs., 2 tabs.

  19. Development of an optically pumped polarized deuterium target

    SciTech Connect

    Young, L.; Holt, R.J.; Green, M.C.; Kowalczyk, R.

    1987-01-01

    The development of a polarized deuterium target for internal use at an electron storage ring is of great interest for fundamental studies in nuclear physics. In order to achieve the maximum allowable target thickness, 10/sup 14/ nuclei/cm/sup 2/, consistent with various constraints imposed by the storage ring environment, a flux of 4 x 10/sup 17/ polarized atom/s must be provided. This flux exceeds the capability of conventional atomic beam sources by an order of magnitude. We have been developing an alternative source based upon the spin-exchange optical pumping method in which the flux is limited only by laser power. 7 refs., 1 fig.

  20. Preliminary design and optimization of an ECC blood pump by means of a parametric approach.

    PubMed

    Montevecchi, F M; Inzoli, F; Redaelli, A; Mammana, M

    1995-07-01

    This study concerns the development of an analytical parametric model of a centrifugal disk pump. The advantage of this kind of approach is to have an adaptable tool as a first step for the design of a pump device. The method allows the evaluation of the velocity profiles and the shear stresses within the impeller disks in the flow domain along with the performance of the device in terms of torque, mechanical power, power loss, head-flow performance, pump efficiency, and hemolytic index. Some simplifying hypotheses are assumed: steady state condition, laminar flow, Newtonian and incompressible fluid. The radial velocity profiles are assumed to be uniform and the flow cross-sectional area is assumed to be constant along the radius. The influence of the housing and secondary flows caused by recirculation are neglected. To test the approach reliability, the model was used to simulate a pump with the following characteristics: an external and internal radius of 50 mm and 5 mm, respectively, and a channel height of 2.5-0.25 mm (h) from inlet to outlet section. The angular velocity omega was varied in the range 500-3,000 rpm. The flow rate has been varied from 1 to 5 L/min. The results show that when the flow rate is increased, head performances obtained using this pump model vary from 411 to 100 mm Hg, and its efficiency varies from 48 to 15%. A parallel simulation has been carried out by means of a Finite Element Method model with an angular velocity equal to 2,000 rpm.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Anion-coupled Na efflux mediated by the human red blood cell Na/K pump

    PubMed Central

    1990-01-01

    The red cell Na/K pump is known to continue to extrude Na when both Na and K are removed from the external medium. Because this ouabain- sensitive flux occurs in the absence of an exchangeable cation, it is referred to as uncoupled Na efflux. This flux is also known to be inhibited by 5 mM Nao but to a lesser extent than that inhibitable by ouabain. Uncoupled Na efflux via the Na/K pump therefore can be divided into a Nao-sensitive and Nao-insensitive component. We used DIDS- treated, SO4-equilibrated human red blood cells suspended in HEPES- buffered (pHo 7.4) MgSO4 or (Tris)2SO4, in which we measured 22Na efflux, 35SO4 efflux, and changes in the membrane potential with the fluorescent dye, diS-C3 (5). A principal finding is that uncoupled Na efflux occurs electroneurally, in contrast to the pump's normal electrogenic operation when exchanging Nai for Ko. This electroneutral uncoupled efflux of Na was found to be balanced by an efflux of cellular anions. (We were unable to detect any ouabain-sensitive uptake of protons, measured in an unbuffered medium at pH 7.4 with a Radiometer pH-STAT.) The Nao-sensitive efflux of Nai was found to be 1.95 +/- 0.10 times the Nao-sensitive efflux of (SO4)i, indicating that the stoichiometry of this cotransport is two Na+ per SO4=, accounting for 60-80% of the electroneutral Na efflux. The remainder portion, that is, the ouabain-sensitive Nao-insensitive component, has been identified as PO4-coupled Na transport and is the subject of a separate paper. That uncoupled Na efflux occurs as a cotransport with anions is supported by the result, obtained with resealed ghosts, that when internal and external SO4 was substituted by the impermeant anion, tartrate i,o, the efflux of Na was inhibited 60-80%. This inhibition could be relieved by the inclusion, before DIDS treatment, of 5 mM Cli,o. Addition of 10 mM Ko to tartrate i,o ghosts, with or without Cli,o, resulted in full activation of Na/K exchange and the pump's electrogenicity

  2. Blood damage related to cardiopulmonary bypass: in vivo and in vitro comparison of two different centrifugal pumps.

    PubMed

    Paparella, Domenico; Galeone, Antonella; Venneri, Maria Teresa; Coviello, Maria; Visicchio, Giuseppe; Cappabianca, Giangiuseppe; Maselli, Giorgia; Marraudino, Nicola; Quaranta, Michele; De Luca Tupputi Schinosa, Luigi

    2004-01-01

    Cardiopulmonary bypass (CPB) induces hemolysis and the activation of the inflammatory and coagulation systems. Several components of the CPB equipment may contribute to such phenomenon. We tested the effects of two differently designed centrifugal pumps (Bio-Pump, Medtronic and Revolution, Cobe) on several markers of hemolysis, coagulation, and inflammation: plasma free hemoglobin,prothrombin fragment 1.2, platelet factor 4, and P-selectin. Twenty patients requiring coronary artery bypass grafting were randomized to undergo CPB with one of the study centrifugal pumps, and 10 experiments (5 for each pump) were performed with a closed loop circuit to assess pumps' performances over 6 circulation hours using human blood. CPB induced a significant elevation of all the tested markers. Neither in the in vivo nor in the in vitro study were significant differences observed between the groups. Because the Revolution centrifugal pump, which was recently designed and distributed, produced results comparable with those obtained with the BioPump, it should be considered as safe as the Bio-Pump to perform clinical CPB.

  3. What Is a Blood Transfusion?

    MedlinePlus

    ... from the NHLBI on Twitter. What Is a Blood Transfusion? A blood transfusion is a safe, common ... Very rarely, serious problems develop. Important Information About Blood The heart pumps blood through a network of ...

  4. Development of a low-voltage piezohydraulic pump for compact hydraulic systems

    NASA Astrophysics Data System (ADS)

    Valdovinos, John; Carman, Gregory P.

    2015-12-01

    Frequency-leveraged electrohydraulic and piezohydraulic pumps represent an alternative technology to traditional electromagnetic motors. The development of a 45 cm3 piezohydraulic pump utilizing a 2 g low-voltage piezoelectric stack is presented. The piezohydraulic pump flow rate and performance were measured and compared to existing pumps in the literature. The flow rate produced by piezohydraulic pump was a nonlinear function of pump operational frequency showing multiple peaks. These flow rate peaks were a function of accumulator size and hydraulic line resonance. The piezohydraulic pump was capable of producing a 125 kPa stall pressure, 186 mL min-1 no-load flow rate, and 0.14 W of power. This pump constitutes one of the two miniature piezohydraulic pumps capable of outputting useful mechanical work. In addition, these results demonstrate that the external hydraulic lines and hydraulic accumulators have a significant effect on the flow and power output of this technology.

  5. Development of a turbine in-tank fuel pump

    SciTech Connect

    Hattori, Y.; Kobayashi, H.; Shinoda, K.

    1987-01-01

    Considerations have been made on using turbine pumps as in-tank fuel pumps for electronic flue injection systems (EFI). Flow channel dimension values, which had not been previously used for these types of pumps, were found to be very suitable for use as a fuel pump. The oil film visualization method was used to observe the flow pattern within the pump, and the results served to improve the flow channel shape. This contributed to designing a compact and efficient high-pressure fuel pump.

  6. Feasibility of a miniature centrifugal rotary blood pump for low-flow circulation in children and infants.

    PubMed

    Takatani, Setsuo; Hoshi, Hideo; Tajima, Kennichi; Ohuchi, Katsuhiro; Nakamura, Makoto; Asama, Junichio; Shimshi, Tadahiko; Yoshikawa, Masaharu

    2005-01-01

    In this study, a seal-less, tiny centrifugal rotary blood pump was designed for low-flow circulatory support in children and infants. The design was targeted to yield a compact and priming volume of 5 ml with a flow rate of 0.5-4 l/min against a head pressure of 40-100 mm Hg. To meet the design requirements, the first prototype had an impeller diameter of 30 mm with six straight vanes. The impeller was supported with a needle-type hydrodynamic bearing and was driven with a six-pole radial magnetic driver. The external pump dimensions included a pump head height of 20 mm, diameter of 49 mm, and priming volume of 5 ml. The weight was 150 g, including the motor driver. In the mock circulatory loop, using fresh porcine blood, the pump yielded a flow of 0.5-4.0 l/min against a head pressure of 40-100 mm Hg at a rotational speed of 1800-4000 rpm using 1/4" inflow and outflow conduits. The maximum flow and head pressure of 5.25 l/min and 244 mm Hg, respectively, were obtained at a rotational speed of 4400 rpm. The maximum electrical-to-hydraulic efficiency occurred at a flow rate of 1.5-3.5 l/min and at a rotational speed of 2000-4400 rpm. The normalized index of hemolysis, which was evaluated using fresh porcine blood, was 0.0076 g/100 l with the impeller in the down-mode and a bearing clearance of 0.1 mm. Further refinement in the bearing and magnetic coupler are required to improve the hemolytic performance of the pump. The durability of the needle-type hydrodynamic bearing and antithrombotic performance of the pump will be performed before clinical applications. The tiny centrifugal blood pump meets the flow requirements necessary to support the circulation of pediatric patients.

  7. ADRC or adaptive controller--A simulation study on artificial blood pump.

    PubMed

    Wu, Yi; Zheng, Qing

    2015-11-01

    Active disturbance rejection control (ADRC) has gained popularity because it requires little knowledge about the system to be controlled, has the inherent disturbance rejection ability, and is easy to tune and implement in practical systems. In this paper, the authors compared the performance of an ADRC and an adaptive controller for an artificial blood pump for end-stage congestive heart failure patients using only the feedback signal of pump differential pressure. The purpose of the control system was to provide sufficient perfusion when the patients' circulation system goes through different pathological and activity variations. Because the mean arterial pressure is equal to the total peripheral flow times the total peripheral resistance, this goal was converted to an expression of making the mean aortic pressure track a reference signal. The simulation results demonstrated that the performance of the ADRC is comparable to that of the adaptive controller with the saving of modeling and computational effort and fewer design parameters: total peripheral flow and mean aortic pressure with ADRC fall within the normal physiological ranges in activity variation (rest to exercise) and in pathological variation (left ventricular strength variation), similar to those values of adaptive controller.

  8. [Magnetic field numerical calculation and analysis for magnetic coupling of centrifugal blood pump for extracorporeal circulation].

    PubMed

    Hu, Zhaoyan; Lu, Lijun; Zhang, Tianyi; Chen, Zhenglong; Zhang, Tao

    2013-12-01

    This paper mainly studies the driving system of centrifugal blood pump for extracorporeal circulation, with the core being disc magnetic coupling. Structure parameters of disc magnetic coupling are related to the ability of transferring magnetic torque. Therefore, it is necessary to carry out disc magnetic coupling permanent magnet pole number (n), air gap length (L(g)), permanent magnet thickness (L(m)), permanent magnet body inside diameter (R(i)) and outside diameter (R(o)), etc. thoroughly. This paper adopts the three-dimensional static magnetic field edge element method of Ansys for numerical calculation, and analyses the relations of magnetic coupling each parameter to transmission magnetic torque. It provides a good theory basis and calculation method for further optimization of the disc magnetic coupling.

  9. FIELD TRIALS OF NEWLY DEVELOPED POSITIVE DISPLACEMENT SUBMERSIBLE PUMP

    SciTech Connect

    Rob Beard

    2003-10-01

    The purpose of this grant was to evaluate under real world conditions the performance of a new type of downhole pump, the hydraulically driven submersible diaphragm pump. This pump is supplied by Pumping Solutions Incorporated, Albuquerque NM. The original scope of the project was to install 10 submersible pumps, and compare that to 10 similar installations of rod pumps. As an operator, the system as tested was not ready for prime time, but has shown the ability to reduce costs, and increase production, if run times can be improved. The PSI group did improve the product and offered excellent service. The latest design appears to be much better, but more test data is needed to show short run life is not a problem. PSI and Beard Oil intend to continue testing the pump with non-government funding. The testing to date did not uncover any fundamental problems that would preclude the widespread use of this pump, and as an operator, I believe that with further improvement and testing, the pump can have a significant impact on stripper well costs. On the positive side, the pump was easy to run, was more power efficient then a rod pump, and is the only submersible that could handle the large quantities of solids typical of the production environment found at the Weber field and in CMB production. The product shows much promise for the future, and with continued design and testing, this type of submersible pump has the potential to become the standard of the industry.

  10. Investigating the impact of non-Newtonian blood models within a heart pump.

    PubMed

    Al-Azawy, Mohammed G; Turan, A; Revell, A

    2017-01-01

    A detailed computational fluid dynamics (CFD) study of transient, turbulent blood flow through a positive displacement left ventricular assist device is performed. Two common models for non-Newtonian blood flow are compared to the Newtonian model to investigate their impact on predicted levels of shear rate and wall shear stress. Given that both parameters are directly relevant to the evaluation of risk from thrombus and haemolysis, there is a need to assess the sensitivity to modelling non-Newtonian flow effects within a pulsatile turbulent flow, in order to identify levels of uncertainly in CFD. To capture the effects of turbulence, the elliptic blending Reynolds stress model is used in the present study, on account of superior performance of second moment closure schemes previously identified by the present authors. The CFD configuration includes two cyclically rotating valves and a moving pusher plate to periodically vary the chamber volume. An overset mesh algorithm is used for each instance of mesh motion, and a zero gap technique was employed to ensure full valve closure. The left ventricular assist device was operated at a pumping rate of 86 BPM (beats per minute) and a systolic duration of 40% of the pumping cycle, in line with existing experimental data to which comparisons are made. The sensitivity of the variable viscosity models is investigated in terms of mean flow field, levels of turbulence and global shear rate, and a non-dimensional index is used to directly evaluate the impact of non-Newtonian effects. The clinical relevance of the results is reported along with a discussion of modelling uncertainties, observing that the turbulent kinetic energy is generally predicted to be higher in non-Newtonian flow than that observed in Newtonian flow. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Shaft/shaft-seal interface characteristics of a multiple disk centrifugal blood pump.

    PubMed

    Manning, K B; Miller, G E

    1999-06-01

    A multiple disk centrifugal pump (MDCP) is under investigation as a potential left ventricular assist device. As is the case with most shaft driven pumps, leakage problems around the shaft/shaft seal interface are of major interest. If leakage were to occur during or after implantation, potential events such as blood loss, clotting, blood damage, and/or infections might result in adverse effects for the patient. Because these effects could be quite disastrous, potential shaft and shaft seal materials have been investigated to determine the most appropriate course to limit these effects. Teflon and nylon shaft seals were analyzed as potential candidates along with a stainless steel shaft and a Melonite coated shaft. The materials and shafts were evaluated under various time durations (15, 30, 45, and 60 min), motor speeds (800, 1,000, 1,200, and 1,400 rpm), and outer diameters (1/2 and 3/4 inches). The motor speed and geometrical configurations were typical for the MDCP under normal physiologic conditions. An air and water study was conducted to analyze the inner diameter wear, the inner temperature values, and the outer temperature values. Statistical comparisons were computed for the shaft seal materials, the shafts, and the outer diameters along with the inner and outer temperatures. The conclusions made from the results indicate that both the tested shaft seal materials and shaft materials are not ideal candidates to be used for the MDCP. Teflon experienced a significant amount of wear in air and water studies. Nylon did experience little wear, but heat generation was an evident problem. A water study on nylon was not conducted because of its molecular structure.

  12. Ultrahigh head pump/turbine development program: Volume 5, Model tests: Basic performance: Final report

    SciTech Connect

    Yokoyama, T.

    1987-01-01

    Pump/turbine model tests for the Ultra-High Head Pump/Turbine Development Program were conducted for evaluating and refining the pump/turbine design, rated speed 720 rpm, net head 1450, output 655 MW on the scale model at Hitachi Hydraulic Research Laboratory. The basic testing resulted in verification of the design, analysis, and performance of the high head pump/turbine.

  13. Optical Pumping / Spin Exchange ^3He Neutron Spin Filter Development

    NASA Astrophysics Data System (ADS)

    Hwang, Shenq-Rong; Coulter, Kevin P.; Chupp, Timothy E.; Welsh, Robert C.

    1998-04-01

    We have instrumented a thermal neutron beam line at the 2MW Ford reactor at the University of Michigan to develop a ^3He neutron spin filter test stand. Due to a large, spin depedent neutron cross section at low energies, polarized ^3He can be used as a neutron spin filter. Our ^3He spin filter is a 10 amagat-cm ^3He cell polarized via optical pumping/spin exchange with Rb. The filter is made of Corning 7056 glass filled with Rb , several atmosphere of ^3He and a few hundred torr nitrogen as buffer gas. We apply two 15W diode array lasers to optically pump Rb. In this presentation we will discuss some progress of this development, including a rotating oven design and a stepping motor driven neutron chopper. Preliminary results of the 10 amagat-cm filter will be presented and compared with theoretical calculations. A study of systematic errors from the data acquisition system and the neutron chopper will also be discussed.

  14. DEVELOPMENT OF A HIGH PERFORMANCE COLD CLIMATE HEAT PUMP

    SciTech Connect

    Horton, W. Travis; Groll, Eckhard A.; Braun, James E.

    2014-06-01

    The primary goals of the proposed project were to develop, test, and evaluate a high performance and cost-effective vapor compression air-source heat pump for use in cold climate regions. Vapor compression heat pumps are a proven technology, and have been used for many years to meet heating requirements for buildings in residential, commercial, and industrial applications. However, in climate regions that experience very low outdoor ambient temperatures both the heating capacity and coefficient of performance (COP) of traditional air-source vapor compression heat pumps drops dramatically with a decrease in the outdoor air temperature. The efficiency of heat pumping equipment has improved substantially over the past 20 years; however, the efficiencies of the highest rated equipment on the market are approaching practical limits that cannot be surpassed without modifications to the basic cycle and possibly the use of additional hardware. In this report, three technologies to improve the efficiency of vapor compression systems are described. These are a) vapor injected compression, b) oil flooded compression and c) hybrid flow control of the evaporator. Compressor prototypes for both, oil flooded and vapor injected compression were developed by Emerson Climate Technologies. For the oil flooded compressor, the oil injection port location was optimized and an internal oil separator was added using several design iterations. After initial testing at Emerson Climate Technologies, further testing was done at Purdue University, and compressor models were developed. These models were then integrated into a system model to determine the achievable improvement of seasonal energy efficiency (SEER) for Minneapolis (Minnesota) climate. For the oil flooded compression, a 34% improvement in seasonal energy efficiency was found while a 21% improvement in seasonal energy efficiency ratio was found for the vapor injected compression. It was found that one benefit of both tested

  15. Development of a Compact, Efficient Cooling Pump for Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    van Boeyen, Roger; Reeh, Jonathan; Trevino, Luis

    2009-01-01

    A compact, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit primary life support systems (PLSSs). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops is discussed.

  16. Development of a Compact, Efficient Cooling Pump for Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    van Boeyen, Roger; Reeh, Jonathan; Trevino, Luis

    2009-01-01

    A compact, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit primary life support systems (PLSSs). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops is discussed.

  17. The Molecular Control of Blood Cell Development

    NASA Astrophysics Data System (ADS)

    Sachs, Leo

    1987-12-01

    The establishment of a cell culture system for the clonal development of blood cells has made it possible to identify the proteins that regulate the growth and differentiation of different blood cell lineages and to discover the molecular basis of normal and abnormal cell development in blood forming tissues. A model system with myeloid blood cells has shown that (i) normal blood cells require different proteins to induce cell multiplication (growth inducers) and cell differentiation (differentiation inducers), (ii) there is a hierarchy of growth inducers as cells become more restricted in their developmental program, and (iii) a cascade of interactions between proteins determines the correct balance between immature and mature cells in normal blood cell development. Gene cloning has shown that there is a family of different genes for these proteins. Normal protein regulators of blood cell development can control the abnormal growth of certain types of leukemic cells and suppress malignancy by incuding differentiation to mature nondividing cells. Chromosome abnormalities that give rise to malignancy in these leukemic cells can be bypassed and their effects nullified by inducing differentiation, which stops cells from multiplying. These blood cell regulatory proteins are active in culture and in the body, and they can be used clinically to correct defects in blood cell development.

  18. Estimation of left ventricular recovery level based on the motor current waveform analysis on circulatory support with centrifugal blood pump.

    PubMed

    Takahashi, K; Uemura, M; Watanabe, N; Ohuchi, K; Nakamura, M; Fukui, Y; Sakamoto, T; Takatani, S

    2001-09-01

    In a mock circulatory loop simulating the left heart bypass using a centrifugal blood pump, analysis of the motor current waveform of the centrifugal pump was performed to derive a useful parameter to evaluate the status of ventricular function. The relationship between the peak, amplitude, and the peak of the fundamental frequency of the power spectral density of the periodic motor current waveform (MCpsdP) that reflected the pulsatile ventricular pressure, and the peak of the left ventricular pressure (LVP) was examined. Although both peak and amplitude of the motor current waveform showed an excellent correlation with the peak LVP, they failed to predict the opening of the aortic valve. The MCpsdP that corresponds to the frequency of the heart rate showed an excellent correlation with the peak LVP throughout the LVP levels, but the slope between them changed with the opening of the aortic valve. Thus, it is possible to follow the change in the LVP and detect even the opening of the aortic valve, and, hence, the recovery of the left ventricle. However, the slope of the linear regression equation varied, depending on the pump speed. This result implies that the MCpsdP can be possibly used to follow the change of ventricular function during circulatory assistance with a centrifugal blood pump as well as to control the pump speed in response to varying ventricular function.

  19. Anion-coupled Na efflux mediated by the human red blood cell Na/K pump

    SciTech Connect

    Dissing, S.; Hoffman, J.F. )

    1990-07-01

    The red cell Na/K pump is known to continue to extrude Na when both Na and K are removed from the external medium. Because this ouabain-sensitive flux occurs in the absence of an exchangeable cation, it is referred to as uncoupled Na efflux. This flux is also known to be inhibited by 5 mM Nao but to a lesser extent than that inhibitable by ouabain. Uncoupled Na efflux via the Na/K pump therefore can be divided into a Nao-sensitive and Nao-insensitive component. We used DIDS-treated, SO4-equilibrated human red blood cells suspended in HEPES-buffered (pHo 7.4) MgSO4 or (Tris)2SO4, in which we measured 22Na efflux, 35SO4 efflux, and changes in the membrane potential with the fluorescent dye, diS-C3 (5). A principal finding is that uncoupled Na efflux occurs electroneurally, in contrast to the pump's normal electrogenic operation when exchanging Nai for Ko. This electroneutral uncoupled efflux of Na was found to be balanced by an efflux of cellular anions. (We were unable to detect any ouabain-sensitive uptake of protons, measured in an unbuffered medium at pH 7.4 with a Radiometer pH-STAT.) The Nao-sensitive efflux of Nai was found to be 1.95 +/- 0.10 times the Nao-sensitive efflux of (SO4)i, indicating that the stoichiometry of this cotransport is two Na+ per SO4=, accounting for 60-80% of the electroneutral Na efflux. The remainder portion, that is, the ouabain-sensitive Nao-insensitive component, has been identified as PO4-coupled Na transport and is the subject of a separate paper. That uncoupled Na efflux occurs as a cotransport with anions is supported by the result, obtained with resealed ghosts, that when internal and external SO4 was substituted by the impermeant anion, tartrate i,o, the efflux of Na was inhibited 60-80%. This inhibition could be relieved by the inclusion, before DIDS treatment, of 5 mM Cli,o.

  20. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    PubMed

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.

  1. Numerical modelling of blood flow behaviour in the valved catheter of the PUCA-pump, a LVAD.

    PubMed

    Morsink, P L; Verkerke, G J; Grootenboer, H J; Mihaylov, D; Rakhorst, G

    1997-05-01

    Mechanical heart assistance, performed by the PUlsatile CAtheter (PUCA) pump, chronologically takes place by sucking blood from the left ventricle and ejecting it into the ascending aorta. Within the pump activity the problem of hemolysis and clotting is encountered. In this study the influence of valve geometry on blood cell damage and stagnant zones has been investigated. A variable valve length coupled to a catheter ejection gap and a variable valve angle have been studied. In case of the studied valve, optimal parameter values have been determined. Compared to small catheter ejection gaps with a corresponding valve length, blood damage is found to be less for large ejection gaps with corresponding valve dimensions. In systole a valve positioned in a 0 degree angle proves to be best, whereas in diastole a +20 degree angle is preferable. Because the system is operating in both systole and diastole, a 0 degree angle valve is applied.

  2. Functional state of the plasma membrane Ca2+ pump in Plasmodium falciparum-infected human red blood cells.

    PubMed

    Tiffert, T; Staines, H M; Ellory, J C; Lew, V L

    2000-05-15

    The active Ca2+ transport properties of malaria-infected, intact red blood cells are unknown. We report here the first direct measurements of Ca2+ pump activity in human red cells infected with Plasmodium falciparum, at the mature, late trophozoite stage. Ca2+ pump activity was measured by the Co2+-exposure method adapted for use in low-K+ media, optimal for parasitised cells. This required a preliminary study in normal, uninfected red cells of the effects of cell volume, membrane potential and external Na+/K+ concentrations on Ca2+ pump performance. Pump-mediated Ca2+ extrusion in normal red cells was only slightly lower in low-K+ media relative to high-K+ media despite the large differences in membrane potential predicted by the Lew-Bookchin red cell model. The effect was prevented by clotrimazole, an inhibitor of the Ca2+-sensitive K+ (KCa) channel, suggesting that it was due to minor cell dehydration. The Ca2+-saturated Ca2+ extrusion rate through the Ca2+ pump (Vmax) of parasitised red cells was marginally inhibited (2-27 %) relative to that of both uninfected red cells from the malaria-infected culture (cohorts), and uninfected red cells from the same donor kept under identical conditions (co-culture). Thus, Ca2+ pump function is largely conserved in parasitised cells up to the mature, late trophozoite stage. A high proportion of the ionophore-induced Ca2+ load in parasitised red cells is taken up by cytoplasmic Ca2+ buffers within the parasite. Following pump-mediated Ca2+ removal from the host, there remained a large residual Ca2+ pool within the parasite which slowly leaked to the host cell, from which it was pumped out.

  3. CAD-design, stress analysis and in vitro evaluation of three leaflet blood-pump valves.

    PubMed

    Knierbein, B; Rosarius, N; Unger, A; Reul, H; Rau, G

    1992-07-01

    The computer-supported development of valves for cardiac-assist devices or artificial hearts is shown in relation to plastic technology. A CAD-system is used for the design development, whereas the dimensioning of the critical and highly stressed membranes is examined by FEM-analyses. Economic manufacture is permitted by the combined thermoforming-dip moulding technique; the blood-side components are made from biocompatible polyurethane to minimize blood damage. The first long-term results in the test set-up are compared to the FEM results.

  4. Development of a nonazeotropic heat pump for crew hygiene water heating

    NASA Technical Reports Server (NTRS)

    Walker, David H.; Deming, Glenn I.

    1991-01-01

    A heat pump system is currently under development to produce hot water for crew hygiene on future manned space missions. The heat pump uses waste heat sources and a nonazeotropic working fluid in a highly efficient cycle. The potential benefits include a reduction in peak power draw from 2 to 5 kW for electric cartridge heaters to just more than 100 W for the heat pump. As part of the heat pump development project, a unique high efficiency compressor was developed to maintain lubrication in a zero-gravity environment.

  5. Centrifugal Force Based Magnetic Micro-Pump Driven by Rotating Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Hashi, S.; Ishiyama, K.

    2011-01-01

    This paper presents a centrifugal force based magnetic micro-pump for the pumping of blood. Most blood pumps are driven by an electrical motor with wired control. To develop a wireless and battery-free blood pump, the proposed pump is controlled by external rotating magnetic fields with a synchronized impeller. Synchronization occurs because the rotor is divided into multi-stage impeller parts and NdFeB permanent magnet. Finally, liquid is discharged by the centrifugal force of multi-stage impeller. The proposed pump length is 30 mm long and19 mm in diameter which much smaller than currently pumps; however, its pumping ability satisfies the requirement for a blood pump. The maximum pressure is 120 mmHg and the maximum flow rate is 5000ml/min at 100 Hz. The advantage of the proposed pump is that the general mechanical problems of a normal blood pump are eliminated by the proposed driving mechanism.

  6. Measurement of the rotor motion and corresponding hemolysis of a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing.

    PubMed

    Kataoka, Hiroyuki; Kimura, Yuichi; Fujita, Hajime; Takatani, Setsuo

    2005-07-01

    This study proposed a centrifugal blood pump with a novel magnetic and hydrodynamic hybrid passive bearing, which consisted of a plain journal bearing for radial stability and a permanent magnetic bearing for axial and tilting stability. We measured the radial motion of the bearing and performed hemolysis tests for the different radial clearance sizes. In the results, it appeared that the radial motion had two modes: the stable center mode, in which the radius of the radial motion rapidly converged to less than 20 microm; and the unstable circle mode, in which the rotor suspension linearly increased with the rotation speed. It also appeared that the pumps with the radial clearance of 80 microm caused more hemolysis than with the smaller clearance sizes in the circle mode. The circle mode was avoidable by the higher rotation or the asymmetric pump structure, but the mechanism of hemolysis in this mode was still unclear.

  7. Development of an Ionic-Liquid Absorption Heat Pump

    SciTech Connect

    Holcomb, Don

    2011-03-29

    Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.

  8. Cardiovascular devices; reclassification of nonroller-type cardiopulmonary bypass blood pumps for cardiopulmonary and circulatory bypass; effective date of requirement for premarket approval for nonroller-type cardiopulmonary bypass blood pumps for temporary ventricular support. Final order.

    PubMed

    2015-06-08

    The Food and Drug Administration (FDA) is issuing a final order to reclassify nonroller-type cardiopulmonary bypass blood pump (NRP) devices for cardiopulmonary and circulatory bypass, a preamendments class III device, into class II (special controls), and to require the filing of a premarket approval application (PMA) for NRP devices for temporary ventricular support. FDA is also revising the title and identification of the regulation for NRP devices in this order.

  9. In vitro study to estimate particle release from a centrifugal blood pump.

    PubMed

    Takami, Yoshiyuki

    2006-05-01

    Centrifugal pumps have been increasingly used in clinical settings. Like roller pumps, centrifugal pumps can cause debris release due to mechanical stress. The objectives of this study were to evaluate in vitro the particle release from a centrifugal pump, Gyro Pump (Japan Medical Materials Co., Osaka, Japan), which is a pivot-bearing supported pump clinically used in Japan, and to identify the released particles. In the clean room Class 10,000, the pump was operated for 24 h at 4000 rpm and 6 L/min in a mock loop filled with lactated Ringer's solution. After 24 h, the sample fluid and a blank were filtered with a 0.45-microm membrane filter for microscopic counting, followed by observation with a scanning electron microscope and element analysis with an X-ray spectrometer. Microscopic countings were 128 +/- 42 in the test samples (n = 10) of the Gyro Pump and 98 +/- 42 in the blank samples (n = 10) (P = 0.12). The oxygen/carbon atomic ratio of the particles in the test samples was 0.32 +/- 0.06, which was similar to the ratio of the particles in the blank sample (0.34 +/- 0.06). The profiles of elements with an X-ray spectrometer showed that the released particles from the Gyro Pump were not derived from the pump materials. In conclusion, an in vitro test system has been established for estimation of particle release from a centrifugal pump. Based upon the results with the system, the Gyro Pump with a pivot-bearing system has little risk to release debris particles even in a severe condition.

  10. Development of an implantable intrathecal drug infusion pump.

    PubMed

    Hong, S; Lee, J S; Park, J W; Nam, K; Choi, J; Lee, J C; Park, J K; Ko, Y P; Jo, Y H

    2004-01-01

    An intrathecal drug infusion system has been designed, manufactured and tested. The system is composed of a drug reservoir and a pump/controller assembly. The drug reservoir made of SUS316L is a negative pressure gas chamber enclosing a bellows type drug chamber. The pump/controller assembly includes a bacterial filter, a controller circuit board, a battery and a micropump, and is connected to a catheter for intrathecal infusion. The micropump implements a peristaltic pumping of the drug by a sequential motion of three pairs of cam and cam-follower. In vitro performance tests were conducted with prototypes.

  11. Ground Source Integrated Heat Pump (GS-IHP) Development

    SciTech Connect

    Baxter, V. D.; Rice, K.; Murphy, R.; Munk, J.; Ally, Moonis; Shen, Bo; Craddick, William; Hearn, Shawn A.

    2013-05-24

    Between October 2008 and May 2013 ORNL and ClimateMaster, Inc. (CM) engaged in a Cooperative Research and Development Agreement (CRADA) to develop a groundsource integrated heat pump (GS-IHP) system for the US residential market. A initial prototype was designed and fabricated, lab-tested, and modeled in TRNSYS (SOLAR Energy Laboratory, et al, 2010) to predict annual performance relative to 1) a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of air-source heat pump (ASHP) and resistance water heater) and 2) a state-of-the-art (SOA) two-capacity ground-source heat pump with desuperheater water heater (WH) option (GSHPwDS). Predicted total annual energy savings, while providing space conditioning and water heating for a 2600 ft{sup 2} (242 m{sup 2}) house at 5 U.S. locations, ranged from 52 to 59%, averaging 55%, relative to the minimum efficiency suite. Predicted energy use for water heating was reduced 68 to 78% relative to resistance WH. Predicted total annual savings for the GSHPwDS relative to the same baseline averaged 22.6% with water heating energy use reduced by 10 to 30% from desuperheater contributions. The 1st generation (or alpha) prototype design for the GS-IHP was finalized in 2010 and field test samples were fabricated for testing by CM and by ORNL. Two of the alpha units were installed in 3700 ft{sup 2} (345 m{sup 2}) houses at the ZEBRAlliance site in Oak Ridge and field tested during 2011. Based on the steady-state performance demonstrated by the GS-IHPs it was projected that it would achieve >52% energy savings relative to the minimum efficiency suite at this specific site. A number of operational issues with the alpha units were identified indicating design changes needed to the system before market introduction could be accomplished. These were communicated to CM throughout the field test period. Based on the alpha unit test results and the diagnostic information coming from the field test

  12. The spiral groove bearing as a mechanism for enhancing the secondary flow in a centrifugal rotary blood pump.

    PubMed

    Amaral, Felipe; Gross-Hardt, Sascha; Timms, Daniel; Egger, Christina; Steinseifer, Ulrich; Schmitz-Rode, Thomas

    2013-10-01

    The rapid evolution of rotary blood pump (RBP) technology in the last few decades was shaped by devices with increased durability, frequently employing magnetic or hydrodynamic suspension techniques. However, the potential for low flow in small gaps between the rotor and pump casing is still a problem for hemocompatibility. In this study, a spiral groove hydrodynamic bearing (SGB) is applied with two distinct objectives: first, as a mechanism to enhance the washout in the secondary flow path of a centrifugal RBP, lowering the exposure to high shear stresses and avoiding thrombus formation; and second, as a way to allow smaller gaps without compromising the washout, enhancing the overall pump efficiency. Computational fluid dynamics was applied and verified via bench-top experiments. An optimization of selected geometric parameters (groove angle, width and depth) focusing on the washout in the gap rather than generating suspension force was conducted. An optimized SGB geometry reduced the residence time of the cells in the gap from 31 to 27 ms, an improvement of 14% compared with the baseline geometry of 200 μm without grooves. When optimizing for pump performance, a 15% smaller gap yielded a slightly better rate of fluid exchange compared with the baseline, followed by a 22% reduction in the volumetric loss from the primary pathway. Finally, an improved washout can be achieved in a pulsatile environment due to the SGB ability to pump inwardly, even in the absence of a pressure head.

  13. NO Metabolites Levels in Human Red Blood Cells are Affected by Palytoxin, an Inhibitor of Na(+)/K(+)-ATPase Pump.

    PubMed

    Carelli-Alinovi, Cristiana; Tellone, Ester; Russo, Anna Maria; Ficarra, Silvana; Pirolli, Davide; Galtieri, Antonio; Giardina, Bruno; Misiti, Francesco

    2014-01-01

    Palytoxin (PTX), a marine toxin, represents an increasing hazard for human health. Despite its high toxicity for biological systems, the mechanisms triggered by PTX, are not well understood. The high affinity of PTX for erythrocyte Na(+)/K(+)-ATPase pump is largely known, and it indicates PTX as a sensitive tool to characterize the signal transducer role for Na(+)/K(+)-ATPase pump. Previously, it has been reported that in red blood cells (RBC), probably via a signal transduction generated by the formation of a PTX-Na(+)/K(+)-ATPase complex, PTX alters band 3 functions and glucose metabolism. The present study addresses the question of which other signaling pathways are regulated by Na(+)/K(+)-ATPase in RBC. Here it has been evidenced that PTX following its interaction with Na(+)/K(+)-ATPase pump, alters RBC morphology and this event is correlated to decreases by 30% in nitrites and nitrates levels, known as markers of plasma membrane eNOS activity. Orthovanadate (OV), an antagonist of PTX binding to Na(+)/K(+)-ATPase pump, was able to reverse the effects elicited by PTX. Finally, current investigation firstly suggests that Na(+)/K(+)-ATPase pump, following its interaction with PTX, triggers a signal transduction involved in NO metabolism regulation.

  14. Development of a diagnostic system for an axial-plunger pump

    NASA Astrophysics Data System (ADS)

    Vakulich, E. A.; Gamov, S. V.; Zhukovskii, A. E.; Mordvintsev, E. Iu.

    An algorithm for diagnosing axial-plunger pumps operating as part of an oil pump station is described. The algorithm has been used in developing a technical diagnostic system for axial-plunger pumps. The system consists of pressure fluctuation transducers, a signal amplifier, a diagnostic module, a controller, an analog-to-digital converter, and a microcomputer. The operation of the diagnostic system is briefly described.

  15. Five-week use of a monopivot centrifugal blood pump as a right ventricular assist device in severe dilated cardiomyopathy.

    PubMed

    Inoue, Takamichi; Kitamura, Tadashi; Torii, Shinzo; Hanayama, Naoji; Oka, Norihiko; Itatani, Keiichi; Tomoyasu, Takahiro; Irisawa, Yusuke; Shibata, Miyuki; Hayashi, Hidenori; Ono, Minoru; Miyaji, Kagami

    2014-03-01

    Right heart failure is a critical complication in patients requiring mechanical ventricular support. However, it is often difficult to provide adequate right ventricular support in the acute phase. A 41-year-old woman diagnosed with dilated cardiomyopathy with severe right heart failure underwent implantation of a paracorporeal pulsatile left ventricular assist device (LVAD, Nipro Corporation, Tokyo, Japan) and a MERA monopivot centrifugal pump (Senko Medical Instrument Manufacturing Co., Ltd., Tokyo, Japan) as a right ventricular assist device (RVAD). The patient developed ischemic enteritis 3 weeks after surgery, necessitating fasting and reversal of anticoagulation therapy. A target international normalized ratio of 1.5 was selected, and aspirin administration was discontinued. Following recovery without thromboembolic events, the patient failed the RVAD discontinuation test. Five weeks after surgery, the monopivot centrifugal pump was exchanged for a pulsatile pump. No thrombus was evident on the centrifugal pump. The patient was undergoing cardiac rehabilitation at the time of this writing and awaiting heart transplantation.

  16. Experimental Study of Micro-Scale Taylor Vortices Within a Co-Axial Mixed-Flow Blood Pump.

    PubMed

    Shu, Fangjun; Tian, Ruijun; Vandenberghe, Stijn; Antaki, James F

    2015-12-29

    Taylor vortices in a miniature mixed-flow rotodynamic blood pump were investigated using micro-scale particle image velocimetry (μ-PIV) and a tracer particle visualization technique. The pump featured a cylindrical rotor (14.9 mm diameter) within a cylindrical bore, having a radial clearance of 500 μm and operated at rotational speeds varying from 1000 to 12 000 rpm. Corresponding Taylor numbers were 700-101 800, respectively. The critical Taylor number was observed to be highly dependent on the ratio of axial to circumferential velocity, increasing from 1200 to 18 000 corresponding to Rossby numbers from 0 to 0.175. This demonstrated a dramatic stabilizing effect of the axial flow. The size of Taylor vortices was also found to be inversely related to Rossby number. It is concluded that Taylor vortices can enhance the mixing in the annular gap and decrease the dwell time of blood cells in the high-shear-rate region, which has the potential to decrease hemolysis and platelet activation within the blood pump.

  17. Intrathoracic and intraabdominal wall implantation of a centrifugal blood pump for circulatory assist.

    PubMed

    Wakisaka, Y; Taenaka, Y; Chikanari, K; Okuzono, Y; Nishimura, T; Endo, S; Nakatani, T; Takano, H

    1998-06-01

    An implantable centrifugal pump (ICP) 320 ml in volume and 830 g in weight has been developed for prolonged circulatory assist. The antithrombogenicity of the ICP is provided by a balancing hole in the center of the impeller. The watertightness and histocompatibility of the ICP are supported by its silicone ring seal and its casing of titanium and acrylic resin, respectively. The total efficiency of the ICP was 30% at a 5 L/min flow rate and a 100 mm Hg head. The heat generation, watertightness, and anatomical fitting of the ICP were assessed in an intrathoracic implantation in a goat (66 kg) and in an intraabdominal wall implantation in a goat (70 kg). Warfarin was given for anticoagulation in each experiment to keep the prothrombin time around 1.7 times that of the control. The temperatures of the pump surface, the pleura, and the room were measured every 3 h. Anatomical fitting was evaluated by pathological observation after the termination of the experiment. The ICP could run for 40 days in the chest cavity and for 11 days in the abdominal wall. The temperature of the motor remained about 1.8 degrees C higher than the reference in both experiments. The ICP was completely covered by a layer of smooth fibrous tissue. The moisture content of the seals remained normal. Although a small amount of atelectasis was found in the lingula, neither lung adhesion nor necrotic change of the chest wall was observed. The inflammation of the surrounding tissue including foreign body reaction and thermal burn was minimal. In conclusion, the ICP has satisfied in vivo testing of its watertightness, exothermicity, and anatomical fitting.

  18. Evaluation of IVAC Variable Pressure Volumetric Pump Model 560 for the delivery of red blood cells, adenine-saline added.

    PubMed

    Gurdak, R G; Anderson, G; Mintz, P D

    1989-02-01

    Mechanical pump systems for the delivery of intravenous solutions have been used for the transfusion of red blood cells. In this study, the IVAC Variable Pressure Volumetric Pump Model 560 was evaluated for that purpose using flow rates of 70 mL/hour and 999 mL/hour through 16-, 19-, and 23-gauge needles and an 18-gauge angiocatheter. The largest degree of hemolysis induced by the delivery system resulted in a mean increase of plasma hemoglobin of 150 mg/L (15 mg/dL); this is equivalent to the loss of 0.03% of the red blood cells. When programmed to deliver 15 mL of red blood cells, the IVAC 560 delivered 15.0 +/- 0.3 mL at a rate of 70 mL/hour and 14.9 +/- 0.3 mL at 999 mL/hour. The authors conclude that the IVAC 560 can be used to deliver red blood cells with a minimal, acceptable level of hemolysis. It also delivers an accurate and precise volume of red blood cells that may be an aid to the transfusionist.

  19. Research and Development on Heat Pumps for Space Conditioning Applications: Proceedings of the DOE/ORNL Heat Pump Conference

    NASA Astrophysics Data System (ADS)

    Jacobs, V. A.; Powell, R. H., Jr.

    1985-08-01

    This conference was planned to provide information on current activities in the US Department of Energy (DOE) and Oak Ridge National Laboratory (ORNL) Building Equipment Research (BER) Program. It was primarily for the benefit of HVAC equipment manufacturers and other interested parties, including utilities, independent research and development organizations, universities, other government groups, and research funding and management organizations. The technical presentations were grouped into two principal subject areas: electric systems and thermally activated systems. Electric-system topics included field performance studies, laboratory experiments on cycling performance, analytical estimates of the benefits of variable capacity and zone control, nonazeotropic refrigerant mixtures, ground-coupled systems, and an analysis of Stirling-cycle heat pumps. In the area of thermally activated heat pumps, presentations centered on the development of absorption systems, Stirling-engine-driven systems, and a linear, free-piston IC-engine compressor. Separate abstracts have been prepared for 27 presentations for inclusion in the Energy Data Base.

  20. Development of a new control device for stabilizing blood level in reservoir during extracorporeal circulation.

    PubMed

    Momose, Naoki; Yamakoshi, Rie; Kokubo, Ryo; Yasuda, Toru; Iwamoto, Norio; Umeda, Chinori; Nakajima, Itsuro; Yanagisawa, Mitsunobu; Tomizawa, Yasuko

    2010-03-01

    We developed a simple device that stabilizes the blood level in the reservoir of the extracorporeal circulation open circuit system by measuring the hydrostatic pressure of the reservoir to control the flow rate of the arterial pump. When the flow rate of the venous return decreases, the rotation speed of the arterial pump is automatically slowed down. Consequently, the blood level in the reservoir is stabilized quickly between two arbitrarily set levels and never falls below the pre-set low level. We conducted a basic experiment to verify the operation of the device, using a mock circuit with water. Commercially available pumps and reservoir were used without modification. The results confirmed that the control method effectively regulates the reservoir liquid level and is highly reliable. The device possibly also functions as a safety device.

  1. Development of advanced heat pump. Part 2: Preliminary test of two-stage compression heat pump

    NASA Astrophysics Data System (ADS)

    Iwatsubo, Tetsushiro; Saikawa, Michinori; Hamamatsu, Teruhide

    1988-03-01

    A heat pump driven by electricity is one of the excellent electricity utilization systems and is promoted to be widely used. An advanced heat pump has been investigated to enlarge its applications in the field of hot water supply for domestic use which will be competitive with city gas and air conditioning in large scale buildings. An experimental unit with two-stage compression system was designed, which has the multi-function of air conditioning and hot water supply, and the trial system was fabricated. In the design, followings were considered; cooperative operations of two compressors by inverter driving, the temperature conditions of both the air for the air conditioning and the heat source, additional setting of the intermediate heat exchanger. The test operation was carried out with checking the start up procedure, the control sequence and so on. The probability of five operation modes: cooling, heating, hot water supply, cooling/hot water supply, and heating/hot water supply, were confirmed. In the mode of heating/hot water supply the hot water temperature was increased to 65 C, the excellent performance in hot water supply was demonstrated.

  2. Development of a Compact Efficient Cooling Pump for Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    vanBoeyen, Roger W.; Reeh, Jonathan A.; Trevino, Luis

    2008-01-01

    With the increasing demands placed on extravehicular activity (EVA) for the International Space Station (ISS) assembly and maintenance, along with planned lunar and Martian missions, the need for increased human productivity and capability becomes ever more critical. This is most readily achieved by reduction in space suit weight and volume, and increased hardware reliability, durability, and operating lifetime. Considerable progress has been made with each successive generation of space suit design; from the Apollo A7L suit, to the current Shuttle Extravehicular Mobile Unit (EMU) suit, and the next generation Constellation Space Suit Element (CSSE). However, one area of space suit design which has continued to lag is the fluid pump used to drive the water cooling loop of the Primary Life Support System (PLSS). The two main types of fluid pumps typically used in space applications are rotodynamic pumps (pumping is achieved through a rotary vaned impeller) and displacement pumps (which includes rotary and diaphragm pumps). The rotating and moving parts found in the pumps and electric motor add significantly to the susceptibility to wear and friction, thermal mismatch, and complexity of the pumps. Electric motor-driven pumps capable of achieving high operational reliability are necessarily large, heavy, and energy inefficient. This report describes a development effort conducted for NASA by Lynntech, Inc., who recently demonstrated the feasibility of an electrochemically-driven fluid cooling pump. With no electric motor and minimal lightweight components, an electrochemically-driven pump is expected to be significantly smaller, lighter and achieve a longer life time than conventional rotodynamic and displacement pumps. By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. It was also demonstrated that these membranes possess the

  3. Development of a Compact Efficient Cooling Pump for Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    vanBoeyen, Roger W.; Reeh, Jonathan A.; Trevino, Luis

    2008-01-01

    With the increasing demands placed on extravehicular activity (EVA) for the International Space Station (ISS) assembly and maintenance, along with planned lunar and Martian missions, the need for increased human productivity and capability becomes ever more critical. This is most readily achieved by reduction in space suit weight and volume, and increased hardware reliability, durability, and operating lifetime. Considerable progress has been made with each successive generation of space suit design; from the Apollo A7L suit, to the current Shuttle Extravehicular Mobile Unit (EMU) suit, and the next generation Constellation Space Suit Element (CSSE). However, one area of space suit design which has continued to lag is the fluid pump used to drive the water cooling loop of the Primary Life Support System (PLSS). The two main types of fluid pumps typically used in space applications are rotodynamic pumps (pumping is achieved through a rotary vaned impeller) and displacement pumps (which includes rotary and diaphragm pumps). The rotating and moving parts found in the pumps and electric motor add significantly to the susceptibility to wear and friction, thermal mismatch, and complexity of the pumps. Electric motor-driven pumps capable of achieving high operational reliability are necessarily large, heavy, and energy inefficient. This report describes a development effort conducted for NASA by Lynntech, Inc., who recently demonstrated the feasibility of an electrochemically-driven fluid cooling pump. With no electric motor and minimal lightweight components, an electrochemically-driven pump is expected to be significantly smaller, lighter and achieve a longer life time than conventional rotodynamic and displacement pumps. By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. It was also demonstrated that these membranes possess the

  4. Efficiency of an air filter at the drainage site in a closed circuit with a centrifugal blood pump: an in vitro study.

    PubMed

    Mitsumaru, A; Yozu, R; Matayoshi, T; Morita, M; Shin, H; Tsutsumi, K; Iino, Y; Kawada, S

    2001-01-01

    In a closed circuit with a centrifugal blood pump, one of the serious obstacles to clinical application is sucking of air bubbles into the drainage circuit. The goal of this study was to investigate the efficiency of an air filter at the drainage site. We used whole bovine blood and the experimental circuit consisted of a drainage circuit, two air filters, a centrifugal blood pump, a membrane oxygenator, a return circuit, and a reservoir. Air was injected into the drainage circuit with a roller pump, and the number and size of air bubbles were measured. The air filter at the drainage site could remove the air bubbles (>40 microm) by itself, but adding a vacuum removed more bubbles (>40 microm) than without vacuum. Our results suggest that an air filter at the drainage site could effectively remove air bubbles, and that adding the filter in a closed circuit with a centrifugal blood pump would be safer.

  5. Development of the Geothermal Heat Pump Market in China; Renewable Energy in China

    SciTech Connect

    Not Available

    2006-03-01

    This case study is one in a series of Success Stories on developing renewable energy technologies in China for a business audience. It focuses on the development of the geothermal heat pump market in China.

  6. Development, testing, and certification of Calmac Mfg. Corp. solar collector and solar operated pump

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1979-01-01

    Development of a rubber tube solar collector and solar operated pump for use with solar heating and cooling systems is discussed. The development hardware, problems encountered during fabrication and testing, and certification statements of performance are included.

  7. Development of low-cost, high-performance non-evaporable getter (NEG) pumps

    SciTech Connect

    Mase, Kazuhiko; Tanaka, Masato; Ida, Naoya; Kodama, Hiraku; Kikuchi, Takashi

    2016-07-27

    Low-cost, high-performance non-evaporable getter (NEG) pumps were constructed using commercial NEG pills comprising 70 wt% Zr, 24.6 wt% V, and 5.4 wt% Fe, a conflat flange with an outer diameter of 70, 152, or 203 mm (DN 40 CF, DN 100 CF, and DN 160 CF, respectively), and a tantalum heater. After activation at 400 °C for 30 min, the pumping speeds of a DN 40 CF NEG pump measured with the orifice method were 47–40, 8–6, 24–17, and 19–15 L/s for H{sub 2}, N{sub 2}, CO, and CO{sub 2} gasses, respectively. NEG pumps using DN 100 CF and DN 160 CF were also developed, and their pumping speeds are estimated. These NEG pumps are favorable alternatives to sputtering ion pumps in VSX beamlines because they do not produce hydrocarbons except during the activation period. The NEG pumps can also be used for accelerators, front ends, end stations, and differential pumping systems.

  8. Assessing the calf pulmonary function during a long-term biventricular assist device study with a centrifugal blood pump.

    PubMed

    Nonaka, Kenji; Linneweber, Joerg; Ichikawa, Seiji; Kawahito, Shinji; Motomura, Tadashi; Ishitoya, Hiroshi; Oestmann, Daniel; Glueck, Julia; Nosé, Yukihiko

    2002-11-01

    Pulmonary congestion due to inappropriate pump flow management is one major problem necessary to avoid during long-term biventricular assist device (BVAD) implantation. Our objective was to assess the effects of pulmonary arterial flow rate and flow rates of both (right and left) bypass pumps. Six healthy calves, which had been implanted with a BVAD system, were selected for this retrospective study. Pulmonary artery flows, both pump flow rates, oxygen saturation of the arterial blood, and pulmonary arterial pressures were assessed as parameters of pulmonary function as was routine clinical evaluation of respiratory rate and character and chest auscultation. The average pulmonary artery flow rate (PAF), systolic pressure of pulmonary artery (sPAP), and oxygen saturation were 148.8 ml/kg per min, 35.1 mm Hg, and 95.3%, respectively. Pulmonary dysfunction occurred in one case, in which the mean PAF, sPAP, and oxygen saturation were 169 ml/kg per min, 66.1 mm Hg, and 90.9%, respectively. The ratio for the right/left pump flow rate (R/L ratio) for the case having pulmonary dysfunction was 1.57 even though the ratio for the other cases was less than 1. Maintaining an R/L ratio less than 1 and/or PAF less than 160 ml/kg per min and PAP less than 50 mm Hg is recommended as the initial conditions to target to avoid pulmonary dysfunction during a BVAD implantation with a beating heart condition.

  9. Development of nonmetallic solar collector and solar-powered pump

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1979-01-01

    Design and building of two unique components for solar heating (1. flatplate solar collector using no metal components, and 2. solar powered pump for heating and cooling systems are outlined in report. Report also discusses hardware, deliverable end items, problems encountered during fabrication and testing, and performance certification.

  10. Capillary Pump Loop (CPL) heat pipe development status report

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The capillary pump loop (CPL) was re-introduced as a potential candidate for the management of large heat loads. It is currently being evaluated for application in the thermal management of large space structures. Test efforts were conducted to establish the feasibility of the CPL heat pipe design.

  11. Duration of red blood cell storage and outcomes in pediatric cardiac surgery: an association found for pump prime blood.

    PubMed

    Ranucci, Marco; Carlucci, Concetta; Isgrò, Giuseppe; Boncilli, Alessandra; De Benedetti, Donatella; De la Torre, Teresa; Brozzi, Simonetta; Frigiola, Alessandro

    2009-01-01

    Cardiac surgery using cardiopulmonary bypass in newborns, infants and small children often requires intraoperative red blood cell transfusions to prime the circuit and oxygenator and to replace blood lost during surgery. The purpose of this study was to investigate the influence of red blood cell storage time prior to transfusion on postoperative morbidity in pediatric cardiac operations. One hundred ninety-two consecutive children aged five years or less who underwent cardiac operations using cardiopulmonary bypass and who received red blood cells for priming the cardiopulmonary bypass circuit comprised the blood-prime group. Forty-seven patients receiving red blood cell transfusions after cardiopulmonary bypass were separately analyzed. Patients in the blood-prime group were divided into two groups based on the duration of storage of the red blood cells they received. The newer blood group included patients who received only red blood cells stored for less than or equal to four days and the older blood group included patients who received red blood cells stored for more than four days. Patients in the newer blood group had a significantly lower rate of pulmonary complications (3.5% versus 14.4%; P = 0.011) as well as a lower rate of acute renal failure (0.8% versus 5.2%; P = 0.154) than patients in the older blood group. Major complications (calculated as a composite score based on pulmonary, neurological, and gastroenterological complications, sepsis and acute renal failure) were found in 6.9% of the patients receiving newer blood and 17.1% of the patients receiving older blood (P = 0.027). After adjusting for other possible confounding variables, red blood cell storage time remained an independent predictor of major morbidity. The same association was not found for patients receiving red blood cell transfusions after cardiopulmonary bypass. The storage time of the red blood cells used for priming the cardiopulmonary bypass circuit in cardiac operations on

  12. The Role of Cardiovascular Muscle Cell Na+-K+ Pump Activity in the Development and Maintenance of Reduced Renal Mass Hypertension in Rats

    DTIC Science & Technology

    1981-09-28

    experimental hypertensive reduced renal mass rats, the objectives of this study were to: 1) assay blood from these animals for presence of a U humoral...REGION IN THE DEVELOPMENT OF REDUCED RENAL MASS HYPERTENSION, VASCULAR Na+-K^ PUMP ACTIVITY, AND CIRCULATING OUABAIN-LIKE FACTOR > 58 ASSAY FOR...clip or one-kidney, one wrap hypertension and bi- laterally nephrectomlzed, smaller, normotensive assay dogs to determine whether blood from the

  13. Development of a proof of concept low temperature 4He Superfluid Magnetic Pump

    NASA Astrophysics Data System (ADS)

    Jahromi, Amir E.; Miller, Franklin K.

    2017-03-01

    We describe the development and experimental results of a proof of concept Superfluid Magnetic Pump in this work. This novel low temperature, no moving part pump can replace the existing bellows-piston driven 4He or 3He-4He mixture compressor/circulators used in various sub Kelvin refrigeration systems such as dilution, Superfluid pulse tube, Stirling, or active magnetic regenerative refrigerators. Due to the superior thermal transport properties of sub-Lambda 4He this pump can also be used as a simple circulator to distribute cooling over large surface areas. Our pump was experimentally shown to produce a maximum flow rate of 440 mg/s (averaged over cycle), 665 mg/s (peak) and produced a maximum pressure difference of 2323 Pa using only the more common isotope of helium, 4He. This pump worked in an ;ideal; thermodynamic state: The experimental results matched with the theoretical values predicted by a computer model. Pump curves were developed to map the performance of this pump. This successful demonstration will enable this novel pump to be implemented in suitable sub Kelvin refrigeration systems.

  14. Numerical investigation of the effects of the clearance gap between the inducer and impeller of an axial blood pump.

    PubMed

    Chan, Weng-Kong; Wong, Yew-Wah; Ong, Wendy; Koh, Sy-Yuan; Chong, Victor

    2005-03-01

    A series of numerical models are generated to investigate the flow characteristics and performance of an axial blood pump. The pump model includes a straightener, an inducer-impeller, and diffuser. Numerical studies of the effects of angular alignment of the inducer and impeller blades and the axial clearance gap between the inducer and impeller are presented in this article. The pump characteristics derived from numerical simulation are validated with experimental data. Numerically simulated results showed a sinusoidal variation in the pressure generated across the pump with changes in angular alignment between the inducer and impeller. This is attributed to additional losses when flow is forced or diverted from the trailing edge of the inducer to either the pressure or suction side of the impeller blade when the alignment between the two sets of blades is not optimal. The pressure generated is a maximum when the impeller blades are at 0 or 30 degrees with respect to the inducer. The effect of rotating the impeller with respect to the inducer causes the sinusoidal pressure variation. In addition, it was observed that when the clearance gap between the inducer and impeller is reduced to 1 mm, the pressure generated is a minimum when compared to the other models. This is attributed to the interference between the inducer and impeller when the gap separating them is too small. The location of the maximum pressure on the pressure side of the impeller blade shifts upstream while its magnitude decreases for small clearance gap between the inducer and the impeller. There was no flow separation in the inducer while small regions of backflow are observed at the impeller trailing edge. Recommendations for future modifications and improvements to the pump design and model simulation are also given.

  15. Infusion pumps and red blood cell damage in transfusion therapy: an integrative revision of the academic literature.

    PubMed

    Wilson, Ana Maria Miranda Martins; Peterlini, Maria Angélica Sorgini; Pedreira, Mavilde da Luz Gonçalves

    2016-08-15

    to obtain information from scientific literature concerning infusion pumps used in administering erythrocyte (red blood cells) and to evaluate the implications in the practical use of this equipment by nurses when conducting transfusions. an integrative revision of the following scientific databases: Pubmed/Medline, Scopus, the Virtual Library for Health, SciELO, Web of Science and Cochrane. The following descriptors were used: "infusion pumps", "blood transfusion", "transfused erythrocyte" and "hemolyis". There were no restrictions on the scope of the initial data and it was finalized in December 2014. 17 articles were identified in accordance with the inclusion and exclusion criteria. all of the publications included in the studies were experimental in vitro and covered the use of infusion pumps in transfusion therapy. A summary of the data was presented in a synoptic chart and an analysis of it generated the following categories: cellular damage and the infusion mechanism. infusion pumps can be harmful to erythrocytes based on the infusion mechanism that is used, as the linear peristaltic pump is more likely to cause hemolysis. Cellular damage is related to the plasmatic liberation of markers that largely dominate free hemoglobin and potassium. We reiterate the need for further research and technological investments to guide the development of protocols that promote safe practices and that can contribute to future clinical studies. identificar na literatura a produção científica acerca dos efeitos de bomba de infusão na administração de hemácias e avaliar as implicações do uso desses equipamentos na prática transfusional de enfermagem. revisão integrativa de literatura nas bases de dados Pubmed/Medline, Scopus, Biblioteca Virtual em Saúde, SciELO, Web of Science e Cochrane, utilizando os descritores "bombas de infusão", "transfusão de sangue", "transfusão de eritrócitos" e "hemólise". A data inicial não foi delimitada e a final foi dezembro de

  16. Development of a Prototype Water Pump for Future Space Suit Applications

    NASA Technical Reports Server (NTRS)

    Hartman, David; Hodgson, Edward; Dionne, Steven; Gervais, Edward, III; Trevino, Luis

    2009-01-01

    NASA's next generation of space suit systems will place new demands on the pump used to circulate cooling water through the life support system and the crew's liquid cooling garment. Long duration missions and frequent EVA require increased durability and reliability; limited resupply mass requirements demand compatibility with recycled water, and changing system design concepts demand increased tolerance for dissolved and free gas and the ability to operate over a broader range of flow rates and discharge pressure conditions. This paper describes the development of a positive displacement prototype pump to meet these needs. A gerotor based design has been adapted to meet pump performance, gas tolerance, and durability requirements while providing a small, lightweight pump assembly. This design has been detailed and implemented using materials selected to address anticipated wat