Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomeno...Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomenon caused by the coupling effect of inlet cannula blocking and pumps suction. Even for cavitation studies on ordinary centrifugal pumps, similar researches on this issue are rare. In this paper, the roles of throttling, rotation speed and fluid viscosity on bubble inception and intensity in a centrifugal blood pump are studied, on the basis of experimental observations. An adjustable throttle valve installed just upstream blood pump inlet is used to simulate the throttling effect of the narrowed inlet cannula. The rotation speed is adjusted from 2 600 r/rain to 3 200 r/min. Glycerin water solutions are used to investigate the influences of kinetic viscosity. Bubbles are recorded with a high-speed video camera. Direct observation shows that different from cavitation in industrial centrifugal pumps, gas nuclei appears at the nearby of vane leading edges while throttling is light, then moves upstream to the joint position of inlet pipe and pump with the closing of the valve. It＇s found that the critical inlet pressure, obtained when bubbles are first observed, decreases linearly with viscosity and the slope is independent with rotation speeds; the critical inlet pressure and the inlet extreme pressure which is obtained when the throttle valve is nearly closed, fall linearly with rotation speed respectively and the relative pressure between them is independent with rotation speed and fluid viscosity. This paper studies experimentally on cavitation in centrifugal blood pump that caused by the failure of assembled short inlet cannula, which mav beneficial the desima of centrifugal blood Dumo with inlet cannula.展开更多
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 pe...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.展开更多
This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient cond...This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.展开更多
In order to improve the surgical treatment of the congenital heart disease patient with single ventricle defect,two axial flow blood pumps,one with diffuser and the other without diffuser,were designed and virtually i...In order to improve the surgical treatment of the congenital heart disease patient with single ventricle defect,two axial flow blood pumps,one with diffuser and the other without diffuser,were designed and virtually implanted into an idealized total cavopulmonary connection(TCPC)model to form two types of Pump-TCPC physiological structure.Computational fluid dynamics(CFD)simulationswere performed to analyze the variations of the hemodynamic characteristics,such as flow field,wall shear stress(WSS),oscillatory shear index(OSI),relative residence time(RRT),between the two Pump-TCPC models.Numerical results indicate that the Pump-TCPC with diffuser has better flow field stability,less damage on endothelial cell of vessel wall,and lower risk of vascular injury and thrombosis formation than that without diffuser.展开更多
Objective To evaluate in vivo antithrombosis property of optimized FW-Ⅱaxial blood pump and provide evidence for future clinical use. Methods A left ventriclepump-descending aorta bypass model was established in five...Objective To evaluate in vivo antithrombosis property of optimized FW-Ⅱaxial blood pump and provide evidence for future clinical use. Methods A left ventriclepump-descending aorta bypass model was established in five healthy sheep (60 70 kg) and the circulation ofthese sheep was assisted by FW-Ⅱaxial blood pump for 2 weeks. At preoperative and postoperative day 1,2,3,7。展开更多
Fluorine-doped hydrogenated amorphous carbon (a-C:H:F) film was deposited on a flow-straightener, impeller and diffuser surface (SUS 304) of an enclosed-impeller type flow blood pump using the ionization deposition me...Fluorine-doped hydrogenated amorphous carbon (a-C:H:F) film was deposited on a flow-straightener, impeller and diffuser surface (SUS 304) of an enclosed-impeller type flow blood pump using the ionization deposition method with a source gas of C6F5H. The surface characteristics of the a-C:H:F film were examined using atomic force microscopy, X-ray photoelectron spectroscopy, and measurements of surface roughness, friction and surface potential. The a-C:H:F film tends to increase surface roughness and the negative surface charge. In addition, the surface energy and friction decrease with fluorine dopant in the a-C:H film. To estimate the hemolytic performance of a blood pump with the a-C:H:F film coating, the amount of hemolysis was measured using a mock circulatory system (in vitro test) with 500 mL of pig blood containing sodium citrate. In vitro test was conducted for 180 min with the blood flow and pump head maintained at 5 L/min and 100 mmHg, respectively. The a-C:H:F film coating reduced the amount of hemolysis and improved the hemolytic performance. Decreasing the surface energy and negative surface charge of the a-C:H:F film contributes to the improvement of the hemolytic performance. The a-C:H:F film coating is thus expected to be utilized in medical technology as a surface coating technology for artificial heart blood pumps.展开更多
From 1997 to 1999, we developed a spiral blood pump. The spiral pump consists of a brushless DC motor, the pump housing, a magnetic-fluid seal, bearings and a spiral impeller. The maximum diameter of the impeller is 2...From 1997 to 1999, we developed a spiral blood pump. The spiral pump consists of a brushless DC motor, the pump housing, a magnetic-fluid seal, bearings and a spiral impeller. The maximum diameter of the impeller is 21.8 mm and minimum is 9.8 mm, the cone angle of the impeller threads is 41.8 degrees. The housing has a maximum diameter of 30 mm. The pump was made from Titanium alloy, the total volume of pump housing and motor was 76 ml and its weight 220g. Methods used: The hydrodynamic performance of the spiral pump was examined from 8 000 to 10 000rpm rotation speeds in a closed circuit loop. This circuit consists of a reservoir, a clamp, two pressure transducers, an electric-magnetic flow rate transducer and glycerin-water solution. The damage test to blood was studied in a smaller circuit loop, that used fresh sheep blood and polyvinyl chloride bag instead of the glycerin-water solution and the reservoir. In this test, the damage of the spiral pump was compared with an axial flow blood pump. Furthermore the simulated condition was 5.0 L/ min flow rate and 100 mmHg pressure. Summarize Results: 1. The flow rate was 4.0 L/min against 120 mmHg pressure when pump rotated 10000 rpm. So the hydrodynamic performance of the spiral blood pump was enough to meet a patient’s need when the blood pump was used as a left ventricular assistant device. 2. The NIH results of three gaps were 0.074±0.022g/100L,0.086±.026g/100L and 0.111±0.034g/100L(n=40) respectively. The best hemolysis result was been at the gap of 0.14 mm. 3. The NIH result of the spiral pump with 0.40gap was 0.111±0.034g/100L, n=40; and the axial flow pump was 0.131±0.030g/100L, n=40 respectively; The mean fibrinogen decreases of two pumps between half of an hour were 4.281±2.098mg/100L and 9.625±5.630mg/100L(n=40). So we can conclude that the damage of the spiral pump to blood was less than the axial flow pump. (P<0.05).展开更多
For rotating blood pump, the sealing problem is a very important one to solve. In this paper, it was introduced that we designed and made a small axial flow pump, applying the magnetic coupling method. The pump consis...For rotating blood pump, the sealing problem is a very important one to solve. In this paper, it was introduced that we designed and made a small axial flow pump, applying the magnetic coupling method. The pump consisted of two pump housings, a brushless DC motor, an impeller with five wanes, a pair of magnetic discs, a spacer, an inlet and an outlet areas , bearings, a support frame, and etc. The pump is made of titanium and is 125 mm length, 147 ml volume, total 380g of weight. Performances of outputting, sealing, heat creating and damage to blood by the pump were investigated in vitro experiment. Results showed for external experiment that: (1)The pressure created by the pump was 90 mmHg, the flow rates were 1.2 L/min, 4 L/min, 5.9 L/min and 7.8 L/min correspondingly to 5000 rpm, 6000 rpm, 7000 rpm and 8000rpm rotation speeds. The hydrodynamic performance of the axial flow blood pump was enough to meet a patient need when the blood pump was used as a left ventricular assistant device. (2)The hemolysis test was studied by the normalized index of hemolysis(NIH). The NIH result of the axial flow pump was 0.08 g/100 L. (3)The outside temperature of the pump didnt change obviously in 120 hours of rotation, and the sealing function was very well.展开更多
Rotodynamic Left Ventricular Assist Devices(LVADs)are critical in managing severe heart failure by providing mechanical circulatory support.Improving these blood pumps'efficiency is crucial for both lowering the d...Rotodynamic Left Ventricular Assist Devices(LVADs)are critical in managing severe heart failure by providing mechanical circulatory support.Improving these blood pumps'efficiency is crucial for both lowering the device's energy consumption and enhancing patient comfort.In this study,the efficiency of a reference centrifugal blood pump was improved through geometric optimization and validated using computational fluid dynamics(CFD)simulations and experiments.The number of blades,inlet width,outlet width,inlet angle,and outlet angle are among the important impeller parameters that were optimized at three different levels.The orthogonal array of the Taguchi design method was used to reduce the 243 possible configurations from the full-factorial experimental design to 27 trial tests.Analysis of Variance(ANOVA)was used to determine the optimal geometric parameters,which led to maximum efficiency after S/N ratios were analyzed using MINITAB-18 software.The performance of the optimized pump was evaluated via CFD at 3300,3150,and 3450 pump rotation speeds,resulting in a 21% increase in hydraulic efficiency at the design point(5 L/min,3300 rpm,and 128.515 mm-Hg).Furthermore,experimental results demonstrated reduced power consumption for the optimized pump compared to the reference pump.This study highlights the potential of geometric optimization in advancing the performance of rotodynamic LVADs.展开更多
Long-lasting stability of the anticoagulant coating on centrifugal blood pumps(CBPs)is of vital importance to ensure the hemocompatibility of the blood circulation system therein.Heparin coatings are often prepared us...Long-lasting stability of the anticoagulant coating on centrifugal blood pumps(CBPs)is of vital importance to ensure the hemocompatibility of the blood circulation system therein.Heparin coatings are often prepared using static wet chemical technique,but these face risks of delamination or deactivation induced by blood flow.Inspired by the flow-shear-stress mediated conformation changes of von Willebrand factor,a novel fluid-driven deposition technique was employed to apply polydopamine-heparin coatings within CBPs.Moreover,most FDA-approved CBPs are designed for high-flow-rate CBPs of major organs like the heart and lungs(1000~8000 ml/min).Few are tailored for low-flow-rate perfusion of other organs such as the liver,kidney and brain(<50-300 mL/min).Our approach addresses this gap by developing low-flow-rate CBPs through anti-thrombogenic coat-ings and anti-hemolytic structural optimizations.In this study,we introduced an axial magnetic direct drive motor with our optimized low-flow-rate CBPs,achieving a stable-low-flow-rate rate ranging from 16.3 mL/min(300 rpm)to 121.0 mL/min(2000 rpm).The resulting CBPs system exhibited enhanced flow stability and hemocompatibility in rabbit model experiments,demonstrating significantly lower hemolysis rates and lower thrombus formation risks.These results indicate that the polydopamine-assisted heparin coating provides shortterm stability under dynamic flow,offering a promising strategy for low-flow-rate CBPs,though its long-term durability and clinical translation potential require further validation.展开更多
Extracorporeal membrane oxygenation(ECMO)is a powerful treatment for patients with severe heart and lung failure.However,bleeding,thrombosis,and hemolysis are three common clinical complications that limit the applica...Extracorporeal membrane oxygenation(ECMO)is a powerful treatment for patients with severe heart and lung failure.However,bleeding,thrombosis,and hemolysis are three common clinical complications that limit the application of ECMO.The high rotational speed of the centrifugal blood pump in an ECMO device can cause significant damage to red blood cells.Therefore,calculation and prediction of this damage are essential to evaluate ECMO devices and the associated pathological hemodynamics.In this study,the internal flow and hemolysis rate of an ECMO centrifugal blood pump are analyzed by computational fluid dynamics simulations.Using the discrete phase method,the damage to red blood cells caused by wall shear stress is investigated under clinical working condition of a centrifugal blood pump,and the hemolysis index of the pump is systematically evaluated to be 1.3%.It is found that the pump impeller is the main factor contributing to hemolysis,accounting for 84% of the total in the pump.The systematic evaluation of hemolysis in an ECMO centrifugal blood pump presented here will help provide theoretical support for risk assessment of ECMO systems in clinical application.展开更多
As the incidence of heart failure continues to rise globally,the demand for interventional blood pumps for heart failure treatment has increased.However,the use of these pumps may lead to infection issues.Given the li...As the incidence of heart failure continues to rise globally,the demand for interventional blood pumps for heart failure treatment has increased.However,the use of these pumps may lead to infection issues.Given the limited research on blood pump infections,methods for evaluating the risk of infection are crucial.In this study,first,an infection risk assessment model for blood pumps was constructed to quantify the relationships among the loss rate of leukocytes,shear strain rate,and temperature.A computational fluid dynamics(CFD)simulation model was subsequently developed to perform fluid–thermal coupling simulations of the internal flow field,temperature field,and index of infection of the blood pump.Furthermore,the impeller design was optimized via an orthogonal experimental design and regression analysis to reduce the risk of infection.Finally,in vitro experiments were conducted to validate the accuracy of the simulation results.Numerical simulations demonstrated that the impeller design significantly influenced the risk of infection.The optimized impeller design(with a larger proximal fillet radius and a smaller blood outlet axial length)reduced the risk of infection.The trends observed in the in vitro experimental results were consistent with the simulation values.The impeller optimization design method proposed in this study effectively reduces the risk of infection in interventional blood pumps,providing a theoretical basis and practical guidance for the design and risk assessment of interventional blood pumps.展开更多
This article presents the design of a new implantable axial-flow blood pump. The special feature of the flow channel inside the blood pump is that the blood is driven by a big-small tandem impeller installed in the in...This article presents the design of a new implantable axial-flow blood pump. The special feature of the flow channel inside the blood pump is that the blood is driven by a big-small tandem impeller installed in the inner hole of the cylinder magnet of a brushless direct current motor. The inner hole makes the main flow channel possible, while the gap between the inner end of the stator and the outer end of the cylinder magnet gives the shape of the tributary flow channel. There is no motor magnet inside the main flow channel, therefore, more blood can pass through it. The gap of the tributary flow channel is very small, but the blood flow in it is not blocked. Thus, the efficiency is increased and the volume and weight of blood pump can be reduced greatly. The outer diameter, length and weight of the manufactured implantable axial-flow blood pump are 29.6 mm, 76 mm and 158 g, respectively. The impeller spins at the speed of 9000 rpm and can generate a pressure head of 100 mmHg and a flow rate of 8 L/rain. In an animal experiment, the blood pump has been successfully applied as a Ventricular Assist Device （VAD） in the chest of a small cow. Besides a mathematical model is established to simulate the flow inside an axial-flow blood pump of implantable VAD. The numerical studies on the performance of the implantable axial-flow blood pump are carried out by combining this mathematical model and the Fluent software. The numerical results agree well with those of experiments, with the maximum error less than 10%.展开更多
Based on established numerical methods and hydrodynamic performance testing facilities,CFD technique are applied to improve the design of the implantable axial flow blood pump and the flow analysis.（1） Applying brus...Based on established numerical methods and hydrodynamic performance testing facilities,CFD technique are applied to improve the design of the implantable axial flow blood pump and the flow analysis.（1） Applying brushless machine magnet steel,reducing its thickness while increasing the length,the flow channel＇s cross-section is increased,with no space connection between the large and the small rotators,and with a cone transition segment from the bearing to the principal axis,the flow is made smoother.The rotating speed is lowered by 1000 rpm-1200 rpm under the same flow rate and pressure head,and thus the hemolysis can be avoided.（2） Different outlet stator guiding vanes are selected for the same blood pump for analyses of hydrodynamic performances and flow fields.An excellent design not only can regulate the rotating flow field into an axial one,reduce the circulation loss and improve the pump efficiency,but also can avoid backflow,vortex and secondary flow at the pump outlet,and thus the thrombus can be prevented.（3） The calf live tests show that some residual clots exist at the inner wall of the outlet connection bends,which are analyzed and explained by CFD techniques and the corresponding improvements are proposed.All results are verified by hydrodynamic performance tests and PIV flow field tests,and consistent conclusions are obtained.展开更多
The numerical simulation of the axial flow impeller blood pump NIVADIII is carried out by using a CFD multiphase flow model. The hydrodynamic performance of the pump and the flow field in the pump are analyzed, and th...The numerical simulation of the axial flow impeller blood pump NIVADIII is carried out by using a CFD multiphase flow model. The hydrodynamic performance of the pump and the flow field in the pump are analyzed, and the shear stress distribution is obtained. A hemolytic prediction model based on the shear stress is built based on the calculation results, and it can be used for qua- ntitative predictions of the hemolytic behavior of a blood pump. Hemolysis tests in vitro were performed 6 times with fresh bovine blood. At each time, the flow of the pump NIVADIII is 5 L/min and the outflow tract pressure is 100 mmHg. According to the tests, the plasma free hemoglobin （FHB） content and the hematocrit （HCT） are measured after 0 s, 0.5 s, 1 s, 1.5 s 4 s. At the end of each experiment Normal Index of Hemolysis （NIH） of NIVADIII is calculated. The average of NIH is 0.0055 g/100L, almost identi- cal with that obtained from the hemolytic prediction model. This method can be applied in the selection stage of a blood pump.展开更多
Blood pumps have been adopted to treat heart failure over the past decades. A novel blood pump adopting the rotor with splitter blades and tandem cascade stator was developed recently. A particle image velocimetry （...Blood pumps have been adopted to treat heart failure over the past decades. A novel blood pump adopting the rotor with splitter blades and tandem cascade stator was developed recently. A particle image velocimetry （P1V） experiment was carried out to verify the design of the blood pump based on computational fluid dynamics （CFD） and further analyze the flow properties in the rotor and stator. The original sized pump model with an acrylic housing and an experiment loop were constructed to perform the optical measurement. The PIV testing was carried out at the rotational speed of 6952±50 r/rain with the flow rate of 3.1 l/rain and at 8186±50 r/min with 3.5 l/rain, respectively. The velocity and the Reynolds shear stress distributions were investigated by PIV and CFD, and the comparisons between them will be helpful for the future blood pump design.展开更多
In recent years,ventricular assist devices(VADs,also known as blood pumps)have gradually entered clinical practice and provide effective treatment for heart failure patients.However,adverse events related to mechanica...In recent years,ventricular assist devices(VADs,also known as blood pumps)have gradually entered clinical practice and provide effective treatment for heart failure patients.However,adverse events related to mechanical blood damage in patients receiving the VAD treatment,were often reported and have become a major concern during the development of VADs,limiting their clinical and economic benefits.Compared with bench and in-vivo testing,computational fluid dynamics(CFD)is flexible and inexpensive,offering the possibility to predict hemodynamics and mechanical blood damage in a purely numerical manner.Thus,CFD has become an important tool for the design,optimization and evaluation of blood pumps.The stringent requirements of blood pumps require high fidelity simulations.Thus,this article reviews the current state of the art in high-fidelity methodologies for simulating blood flow and blood damage for the development and evaluation of rotary blood pumps;design and optimization methods of rotatory blood pumps using CFD,as well as future challenges.展开更多
The non-physiologic turbulent flows in centrifugal rotary blood pumps (RBPs) may result in complications such as the hemolysis and the platelet activation. Recent researches suggest that the turbulent viscous dissipat...The non-physiologic turbulent flows in centrifugal rotary blood pumps (RBPs) may result in complications such as the hemolysis and the platelet activation. Recent researches suggest that the turbulent viscous dissipation in the smallest eddies is the main factor of the blood trauma caused by the turbulent flow. The turbulent viscous shear stress (TVSS) was taken as the realistic physical force acting on the cells. However, limited by the temporal and spatial resolutions of the instrumentation currently available, very limited studies are available for the TVSS in the RBPs. In this paper, the large eddy particle image velocimetry (PIV) method is used to estimate the turbulent dissipation rate in the sub-grid scale, to investigate the effect of the TVSS on the blood trauma. Detailed flow characteristics, such as the relative velocity vectors, the estimated TVSS levels and the Kolmogorov length scales, are analyzed in three impeller phases at three constant flow rates (3 L/min, 5 L/min and 7 L/min). Over the measures range in this study, the maximum TVSS in the investigated RBP is lower than the reported critical value of stress. This study demonstrates that the large eddy PIV method is effective to evaluate the flow-dependent force on the cells. On the other hand, it is found that the TVSS is highly dependent on the flow behavior. Under severe off-design conditions, the complex flow characteristics, such as the flow separation and the vortical structures, will increase the TVSS. Thus, in order to reduce the hemolysis in the RBPs, the flow disturbance, induced by the departure of the incidence angle, should be avoided during the design of the RBPs.展开更多
Centrifugal blood pumps have become popular for adult extracorporeal membrane oxygenation(ECMO)due to their superior blood handling and reduced thrombosis risk featured by their secondary flow paths that avoid stagnan...Centrifugal blood pumps have become popular for adult extracorporeal membrane oxygenation(ECMO)due to their superior blood handling and reduced thrombosis risk featured by their secondary flow paths that avoid stagnant areas.However,the high rotational speed within a centrifugal blood pump can introduce high shear stress,causing a significant shear-induced hemolysis rate.The Revolution pump,the Rotaflow pump,and the CentriMag pump are three of the leading centrifugal blood pumps on the market.Although many experimental and computational studies have focused on evaluating the hydraulic and hemolytic performances of the Rotaflow and CentriMag pumps,there are few on the Revolution pump.Furthermore,a thorough direct comparison of these three pumps'flow characteristics and hemolysis is not available.In this study,we conducted a computational and experimental analysis to compare the hemolytic performances of the Revolution,Rotaflow,and CentriMag pumps operating under a clinically relevant condition,i.e.,the blood flow rate of 5 L/min and pump pressure head of 350 mmHg,for adult ECMO support.In silico simulations were used to characterize the shear stress distributions and predict the hemolysis index,while in vitro blood loop studies experimentally determined hemolysis performance.Comparative simulation results and experimental data demonstrated that the CentriMag pump caused the lowest hemolysis while the Revolution pump generated the highest hemolysis.展开更多
BACKGROUND： Ultraviolet blood irradiation and oxygenation （UBIO） has obtained better clinical effect in treating acute cerebral infarction, but the mechanism underlying this effect remains unclear. OBJECTIVE： To o...BACKGROUND： Ultraviolet blood irradiation and oxygenation （UBIO） has obtained better clinical effect in treating acute cerebral infarction, but the mechanism underlying this effect remains unclear. OBJECTIVE： To observe the effect of UBIO on the nerve function and activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase activities on the red blood cell （RBC） membrane of patients with acute cerebral infarction. DESIGN： A randomized and controlled study.SETTING： Department of Neurology, Xiangfan Central Hospital.PARTICIPANTS： From January 2000 to December 2001, excluding those above 70 years old, 58 cases of 700 patients with acute cerebral infarction admitted in the Department of Neurology, Xiangfan Central Hospital, were recruited and divided into two groups according to the random number table： UBIO treated group （n=28）, including 17 males and 11 females, aged 40-68 years; and control group （n=30）, including 20 males and 10 females, aged 44-69 years. All the patients agreed to participate in the therapeutic program and detected items. The general informations were comparable without obvious differences between the two groups （P 〉 0.05）.METHODS： ① The patients in both groups received routine treatments, besides, those in the UBIO treated group were given UBIO treatment by using the XL-200 type therapeutic apparatus produced in Shijiazhuang, whose ultraviolet wave was set at 253.7 nm with the energy density of 0.568 J/m^2 per second, UBIO treatment started from the second day after admission, once every other day, with a single course consisting of 5-7 treatments. ② In the UBIO treated group, the venous blood was sampled before and after the first, third and the completion of the treatment course respectively, the venous blood was taken at each corresponding time point in the control group. After centrifugation of the blood at 10 000 rounds per minute, the RBC membrane was separated and then the activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase were detected by means of phosphorus determination.③ The nerve function was scored before and after treatment in both groups with European stroke scale, which included 13 items, the total score was 0-100 points, the higher the score, the better the nerve function. MAIN OUTCOME MEASURES ：①Score of European stroke scale before and after treatment in both groups.② Comparison of the activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase on RBC membrane between the two groups before treatment and after the first, third and the completion of the treatment. RESULTS： All the 58 patients with cerebral infarction were involved in the analysis of results.① The score of European stroke scale had no obvious difference between the two groups [（49.31±11.48）, （50.58±12.63）, P 〉 0.05], and it was obviously higher in the UBIO treated group than in the control group after treatment [84.66±13.75）, （77.05±11.17）, P 〈 0.05].②The activity of K^＋-Na^＋-ATPase on RBC membrane in the UBIO treated group was significantly increased after the first and third treatment as compared with before treatment [（31.56±19.25）, （27.64±15.83）, （17.67±13.83）, P 〈 0.01], it was still higher after the completion of the treatment than before treatment without obvious difference [（20.86±14.53）, P 〉 0.05]. After the first and third treatment, it was obviously higher in the UBIO treated group than in the control group [19.31±11.88）, （17.44±10.42）, P 〈 0.01]. ③ In the UBIO treated group, Ca2^＋-Mg2^＋-ATPase activity on RBC membrane significantly increased after the first treatment and remained higher than the pre-treatment level throughout the treatment [（27.49±14.72）, （17.41±4.82）, P 〈 0.01]. The activity of Ca2^＋-Mg2^＋-ATPase on RBC membrane was markedly higher in the UBIO treated group than in the control group after after the first, third and the completion of treatment respectively [（24.83±12.88）, （17.70±5.69）; （28.08±13.44）, （16.32±5.29）; （17.42±6.04）, P〈 0.05-0.01]. CONCLUSION： The effect of UBIO treatment against acute cerebral infarction may be mediated by the increased K^＋-Na^＋ ATPase and Ca2^＋-Mg2^＋-ATPase activities on RBC membrane, which enhances the RBC transformation ability so as to lower RBC aggregation and correct high blood viscosity.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51275461)the Zhejiang Provincial Natural Science Foundation of China(Grant No.Z1110189)
文摘Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomenon caused by the coupling effect of inlet cannula blocking and pumps suction. Even for cavitation studies on ordinary centrifugal pumps, similar researches on this issue are rare. In this paper, the roles of throttling, rotation speed and fluid viscosity on bubble inception and intensity in a centrifugal blood pump are studied, on the basis of experimental observations. An adjustable throttle valve installed just upstream blood pump inlet is used to simulate the throttling effect of the narrowed inlet cannula. The rotation speed is adjusted from 2 600 r/rain to 3 200 r/min. Glycerin water solutions are used to investigate the influences of kinetic viscosity. Bubbles are recorded with a high-speed video camera. Direct observation shows that different from cavitation in industrial centrifugal pumps, gas nuclei appears at the nearby of vane leading edges while throttling is light, then moves upstream to the joint position of inlet pipe and pump with the closing of the valve. It＇s found that the critical inlet pressure, obtained when bubbles are first observed, decreases linearly with viscosity and the slope is independent with rotation speeds; the critical inlet pressure and the inlet extreme pressure which is obtained when the throttle valve is nearly closed, fall linearly with rotation speed respectively and the relative pressure between them is independent with rotation speed and fluid viscosity. This paper studies experimentally on cavitation in centrifugal blood pump that caused by the failure of assembled short inlet cannula, which mav beneficial the desima of centrifugal blood Dumo with inlet cannula.
基金supported by National Natural Science Foundation of China(Grant No.51275461)Zhejiang Provincial Natural Science Foundation of China(Grant No.Z1110189)+1 种基金National Hi-tech Research and Development Program of China(863 ProgramGrant No.2009AA045401)
文摘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.
文摘This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.
基金This work has been supported by the Natural Science Foundation of China(No.11872152).
文摘In order to improve the surgical treatment of the congenital heart disease patient with single ventricle defect,two axial flow blood pumps,one with diffuser and the other without diffuser,were designed and virtually implanted into an idealized total cavopulmonary connection(TCPC)model to form two types of Pump-TCPC physiological structure.Computational fluid dynamics(CFD)simulationswere performed to analyze the variations of the hemodynamic characteristics,such as flow field,wall shear stress(WSS),oscillatory shear index(OSI),relative residence time(RRT),between the two Pump-TCPC models.Numerical results indicate that the Pump-TCPC with diffuser has better flow field stability,less damage on endothelial cell of vessel wall,and lower risk of vascular injury and thrombosis formation than that without diffuser.
文摘Objective To evaluate in vivo antithrombosis property of optimized FW-Ⅱaxial blood pump and provide evidence for future clinical use. Methods A left ventriclepump-descending aorta bypass model was established in five healthy sheep (60 70 kg) and the circulation ofthese sheep was assisted by FW-Ⅱaxial blood pump for 2 weeks. At preoperative and postoperative day 1,2,3,7。
文摘Fluorine-doped hydrogenated amorphous carbon (a-C:H:F) film was deposited on a flow-straightener, impeller and diffuser surface (SUS 304) of an enclosed-impeller type flow blood pump using the ionization deposition method with a source gas of C6F5H. The surface characteristics of the a-C:H:F film were examined using atomic force microscopy, X-ray photoelectron spectroscopy, and measurements of surface roughness, friction and surface potential. The a-C:H:F film tends to increase surface roughness and the negative surface charge. In addition, the surface energy and friction decrease with fluorine dopant in the a-C:H film. To estimate the hemolytic performance of a blood pump with the a-C:H:F film coating, the amount of hemolysis was measured using a mock circulatory system (in vitro test) with 500 mL of pig blood containing sodium citrate. In vitro test was conducted for 180 min with the blood flow and pump head maintained at 5 L/min and 100 mmHg, respectively. The a-C:H:F film coating reduced the amount of hemolysis and improved the hemolytic performance. Decreasing the surface energy and negative surface charge of the a-C:H:F film contributes to the improvement of the hemolytic performance. The a-C:H:F film coating is thus expected to be utilized in medical technology as a surface coating technology for artificial heart blood pumps.
基金The project was support by National Nine- Five Years Foundation
文摘From 1997 to 1999, we developed a spiral blood pump. The spiral pump consists of a brushless DC motor, the pump housing, a magnetic-fluid seal, bearings and a spiral impeller. The maximum diameter of the impeller is 21.8 mm and minimum is 9.8 mm, the cone angle of the impeller threads is 41.8 degrees. The housing has a maximum diameter of 30 mm. The pump was made from Titanium alloy, the total volume of pump housing and motor was 76 ml and its weight 220g. Methods used: The hydrodynamic performance of the spiral pump was examined from 8 000 to 10 000rpm rotation speeds in a closed circuit loop. This circuit consists of a reservoir, a clamp, two pressure transducers, an electric-magnetic flow rate transducer and glycerin-water solution. The damage test to blood was studied in a smaller circuit loop, that used fresh sheep blood and polyvinyl chloride bag instead of the glycerin-water solution and the reservoir. In this test, the damage of the spiral pump was compared with an axial flow blood pump. Furthermore the simulated condition was 5.0 L/ min flow rate and 100 mmHg pressure. Summarize Results: 1. The flow rate was 4.0 L/min against 120 mmHg pressure when pump rotated 10000 rpm. So the hydrodynamic performance of the spiral blood pump was enough to meet a patient’s need when the blood pump was used as a left ventricular assistant device. 2. The NIH results of three gaps were 0.074±0.022g/100L,0.086±.026g/100L and 0.111±0.034g/100L(n=40) respectively. The best hemolysis result was been at the gap of 0.14 mm. 3. The NIH result of the spiral pump with 0.40gap was 0.111±0.034g/100L, n=40; and the axial flow pump was 0.131±0.030g/100L, n=40 respectively; The mean fibrinogen decreases of two pumps between half of an hour were 4.281±2.098mg/100L and 9.625±5.630mg/100L(n=40). So we can conclude that the damage of the spiral pump to blood was less than the axial flow pump. (P<0.05).
基金The projectwas supported by National Nine- Five Years Foundation(96 - 90 6 - 0 2 - 14 )
文摘For rotating blood pump, the sealing problem is a very important one to solve. In this paper, it was introduced that we designed and made a small axial flow pump, applying the magnetic coupling method. The pump consisted of two pump housings, a brushless DC motor, an impeller with five wanes, a pair of magnetic discs, a spacer, an inlet and an outlet areas , bearings, a support frame, and etc. The pump is made of titanium and is 125 mm length, 147 ml volume, total 380g of weight. Performances of outputting, sealing, heat creating and damage to blood by the pump were investigated in vitro experiment. Results showed for external experiment that: (1)The pressure created by the pump was 90 mmHg, the flow rates were 1.2 L/min, 4 L/min, 5.9 L/min and 7.8 L/min correspondingly to 5000 rpm, 6000 rpm, 7000 rpm and 8000rpm rotation speeds. The hydrodynamic performance of the axial flow blood pump was enough to meet a patient need when the blood pump was used as a left ventricular assistant device. (2)The hemolysis test was studied by the normalized index of hemolysis(NIH). The NIH result of the axial flow pump was 0.08 g/100 L. (3)The outside temperature of the pump didnt change obviously in 120 hours of rotation, and the sealing function was very well.
基金supported financially by the Konya Technical University,Coordinatorship of Scientific Research Projects under project Grant No.191010038.
文摘Rotodynamic Left Ventricular Assist Devices(LVADs)are critical in managing severe heart failure by providing mechanical circulatory support.Improving these blood pumps'efficiency is crucial for both lowering the device's energy consumption and enhancing patient comfort.In this study,the efficiency of a reference centrifugal blood pump was improved through geometric optimization and validated using computational fluid dynamics(CFD)simulations and experiments.The number of blades,inlet width,outlet width,inlet angle,and outlet angle are among the important impeller parameters that were optimized at three different levels.The orthogonal array of the Taguchi design method was used to reduce the 243 possible configurations from the full-factorial experimental design to 27 trial tests.Analysis of Variance(ANOVA)was used to determine the optimal geometric parameters,which led to maximum efficiency after S/N ratios were analyzed using MINITAB-18 software.The performance of the optimized pump was evaluated via CFD at 3300,3150,and 3450 pump rotation speeds,resulting in a 21% increase in hydraulic efficiency at the design point(5 L/min,3300 rpm,and 128.515 mm-Hg).Furthermore,experimental results demonstrated reduced power consumption for the optimized pump compared to the reference pump.This study highlights the potential of geometric optimization in advancing the performance of rotodynamic LVADs.
基金Beijing Natural Science Foundation 7244510(MJ)CHF-brain 2024-1-5041(MJ)+7 种基金CHF-brain 2024-3-2062(ML)Collaborative innovation project by Chinese Institutes for Medical Research CX25XT02(MJ)National Natural Science Foundation of China 82402444(MJ),52531008(ML),82102220(ML),82027802(XJ)Beijing Hospitals Authority Clinical Medicine Development of special funding support(YGLX202527)(MJ)Excellent Youth Fund of Capital Medical University B2305(ML)The Non-profit Central Research Institute Fund of Chinese Academy of Medical 2023-JKCS-09(ML),2023-JKCS-13(MJ)Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support from Yangfan Project YGLX202325(ML)Research Funding on Translational Medicine from Beijing Municipal Science and Technology Commission Z221100007422023(ML)。
文摘Long-lasting stability of the anticoagulant coating on centrifugal blood pumps(CBPs)is of vital importance to ensure the hemocompatibility of the blood circulation system therein.Heparin coatings are often prepared using static wet chemical technique,but these face risks of delamination or deactivation induced by blood flow.Inspired by the flow-shear-stress mediated conformation changes of von Willebrand factor,a novel fluid-driven deposition technique was employed to apply polydopamine-heparin coatings within CBPs.Moreover,most FDA-approved CBPs are designed for high-flow-rate CBPs of major organs like the heart and lungs(1000~8000 ml/min).Few are tailored for low-flow-rate perfusion of other organs such as the liver,kidney and brain(<50-300 mL/min).Our approach addresses this gap by developing low-flow-rate CBPs through anti-thrombogenic coat-ings and anti-hemolytic structural optimizations.In this study,we introduced an axial magnetic direct drive motor with our optimized low-flow-rate CBPs,achieving a stable-low-flow-rate rate ranging from 16.3 mL/min(300 rpm)to 121.0 mL/min(2000 rpm).The resulting CBPs system exhibited enhanced flow stability and hemocompatibility in rabbit model experiments,demonstrating significantly lower hemolysis rates and lower thrombus formation risks.These results indicate that the polydopamine-assisted heparin coating provides shortterm stability under dynamic flow,offering a promising strategy for low-flow-rate CBPs,though its long-term durability and clinical translation potential require further validation.
基金supported by the Medical and Health Research Project of Zhejiang Province(Grant No.2025ky799).
文摘Extracorporeal membrane oxygenation(ECMO)is a powerful treatment for patients with severe heart and lung failure.However,bleeding,thrombosis,and hemolysis are three common clinical complications that limit the application of ECMO.The high rotational speed of the centrifugal blood pump in an ECMO device can cause significant damage to red blood cells.Therefore,calculation and prediction of this damage are essential to evaluate ECMO devices and the associated pathological hemodynamics.In this study,the internal flow and hemolysis rate of an ECMO centrifugal blood pump are analyzed by computational fluid dynamics simulations.Using the discrete phase method,the damage to red blood cells caused by wall shear stress is investigated under clinical working condition of a centrifugal blood pump,and the hemolysis index of the pump is systematically evaluated to be 1.3%.It is found that the pump impeller is the main factor contributing to hemolysis,accounting for 84% of the total in the pump.The systematic evaluation of hemolysis in an ECMO centrifugal blood pump presented here will help provide theoretical support for risk assessment of ECMO systems in clinical application.
文摘As the incidence of heart failure continues to rise globally,the demand for interventional blood pumps for heart failure treatment has increased.However,the use of these pumps may lead to infection issues.Given the limited research on blood pump infections,methods for evaluating the risk of infection are crucial.In this study,first,an infection risk assessment model for blood pumps was constructed to quantify the relationships among the loss rate of leukocytes,shear strain rate,and temperature.A computational fluid dynamics(CFD)simulation model was subsequently developed to perform fluid–thermal coupling simulations of the internal flow field,temperature field,and index of infection of the blood pump.Furthermore,the impeller design was optimized via an orthogonal experimental design and regression analysis to reduce the risk of infection.Finally,in vitro experiments were conducted to validate the accuracy of the simulation results.Numerical simulations demonstrated that the impeller design significantly influenced the risk of infection.The optimized impeller design(with a larger proximal fillet radius and a smaller blood outlet axial length)reduced the risk of infection.The trends observed in the in vitro experimental results were consistent with the simulation values.The impeller optimization design method proposed in this study effectively reduces the risk of infection in interventional blood pumps,providing a theoretical basis and practical guidance for the design and risk assessment of interventional blood pumps.
基金supported by the National High Technology Research and Development program of China (863 Program, Grant No. 2007AA02Z439)The Program for Outstanding Medical Academic Leader of Shanghai
文摘This article presents the design of a new implantable axial-flow blood pump. The special feature of the flow channel inside the blood pump is that the blood is driven by a big-small tandem impeller installed in the inner hole of the cylinder magnet of a brushless direct current motor. The inner hole makes the main flow channel possible, while the gap between the inner end of the stator and the outer end of the cylinder magnet gives the shape of the tributary flow channel. There is no motor magnet inside the main flow channel, therefore, more blood can pass through it. The gap of the tributary flow channel is very small, but the blood flow in it is not blocked. Thus, the efficiency is increased and the volume and weight of blood pump can be reduced greatly. The outer diameter, length and weight of the manufactured implantable axial-flow blood pump are 29.6 mm, 76 mm and 158 g, respectively. The impeller spins at the speed of 9000 rpm and can generate a pressure head of 100 mmHg and a flow rate of 8 L/rain. In an animal experiment, the blood pump has been successfully applied as a Ventricular Assist Device （VAD） in the chest of a small cow. Besides a mathematical model is established to simulate the flow inside an axial-flow blood pump of implantable VAD. The numerical studies on the performance of the implantable axial-flow blood pump are carried out by combining this mathematical model and the Fluent software. The numerical results agree well with those of experiments, with the maximum error less than 10%.
基金supported by the National High Technology Research and Development Program of China (863 Program Grant No. 2007AA02Z439)The Program for Outstanding Medical Academic Leader of Shanghai
文摘Based on established numerical methods and hydrodynamic performance testing facilities,CFD technique are applied to improve the design of the implantable axial flow blood pump and the flow analysis.（1） Applying brushless machine magnet steel,reducing its thickness while increasing the length,the flow channel＇s cross-section is increased,with no space connection between the large and the small rotators,and with a cone transition segment from the bearing to the principal axis,the flow is made smoother.The rotating speed is lowered by 1000 rpm-1200 rpm under the same flow rate and pressure head,and thus the hemolysis can be avoided.（2） Different outlet stator guiding vanes are selected for the same blood pump for analyses of hydrodynamic performances and flow fields.An excellent design not only can regulate the rotating flow field into an axial one,reduce the circulation loss and improve the pump efficiency,but also can avoid backflow,vortex and secondary flow at the pump outlet,and thus the thrombus can be prevented.（3） The calf live tests show that some residual clots exist at the inner wall of the outlet connection bends,which are analyzed and explained by CFD techniques and the corresponding improvements are proposed.All results are verified by hydrodynamic performance tests and PIV flow field tests,and consistent conclusions are obtained.
基金Project supported by the National High Technology Research and Development Program of China (863 Program,Grant No. 2007AA02Z439)The Key Disciplines Group Construction Project of Pudong Health Bureau of Shanghai (Grant No. PKzxkq2010-01)the Outstanding Leaders Training Program of Pudong Health Bureau of Shanghai (Grant No.PKR2011-01)
文摘The numerical simulation of the axial flow impeller blood pump NIVADIII is carried out by using a CFD multiphase flow model. The hydrodynamic performance of the pump and the flow field in the pump are analyzed, and the shear stress distribution is obtained. A hemolytic prediction model based on the shear stress is built based on the calculation results, and it can be used for qua- ntitative predictions of the hemolytic behavior of a blood pump. Hemolysis tests in vitro were performed 6 times with fresh bovine blood. At each time, the flow of the pump NIVADIII is 5 L/min and the outflow tract pressure is 100 mmHg. According to the tests, the plasma free hemoglobin （FHB） content and the hematocrit （HCT） are measured after 0 s, 0.5 s, 1 s, 1.5 s 4 s. At the end of each experiment Normal Index of Hemolysis （NIH） of NIVADIII is calculated. The average of NIH is 0.0055 g/100L, almost identi- cal with that obtained from the hemolytic prediction model. This method can be applied in the selection stage of a blood pump.
基金supported by the National Natural Science Foundation of China (Grant Nos.50676004 and 50736007)the Science Foundation of Fuwai hospital (Grant No:2009F-010)the Key Subject Foundation of Beijing:Fluid Machinery and Engineering
文摘Blood pumps have been adopted to treat heart failure over the past decades. A novel blood pump adopting the rotor with splitter blades and tandem cascade stator was developed recently. A particle image velocimetry （P1V） experiment was carried out to verify the design of the blood pump based on computational fluid dynamics （CFD） and further analyze the flow properties in the rotor and stator. The original sized pump model with an acrylic housing and an experiment loop were constructed to perform the optical measurement. The PIV testing was carried out at the rotational speed of 6952±50 r/rain with the flow rate of 3.1 l/rain and at 8186±50 r/min with 3.5 l/rain, respectively. The velocity and the Reynolds shear stress distributions were investigated by PIV and CFD, and the comparisons between them will be helpful for the future blood pump design.
基金the National Natural Science Foundation of China(No.12072216)the Mobility Program of the Sino-German Center(No.M-0231).
文摘In recent years,ventricular assist devices(VADs,also known as blood pumps)have gradually entered clinical practice and provide effective treatment for heart failure patients.However,adverse events related to mechanical blood damage in patients receiving the VAD treatment,were often reported and have become a major concern during the development of VADs,limiting their clinical and economic benefits.Compared with bench and in-vivo testing,computational fluid dynamics(CFD)is flexible and inexpensive,offering the possibility to predict hemodynamics and mechanical blood damage in a purely numerical manner.Thus,CFD has become an important tool for the design,optimization and evaluation of blood pumps.The stringent requirements of blood pumps require high fidelity simulations.Thus,this article reviews the current state of the art in high-fidelity methodologies for simulating blood flow and blood damage for the development and evaluation of rotary blood pumps;design and optimization methods of rotatory blood pumps using CFD,as well as future challenges.
基金Project supported by the National Natural Science Foundation of China(Grant No.51536008)the National Key R&D Program of China(Grant No.2018 YFB0606101).
文摘The non-physiologic turbulent flows in centrifugal rotary blood pumps (RBPs) may result in complications such as the hemolysis and the platelet activation. Recent researches suggest that the turbulent viscous dissipation in the smallest eddies is the main factor of the blood trauma caused by the turbulent flow. The turbulent viscous shear stress (TVSS) was taken as the realistic physical force acting on the cells. However, limited by the temporal and spatial resolutions of the instrumentation currently available, very limited studies are available for the TVSS in the RBPs. In this paper, the large eddy particle image velocimetry (PIV) method is used to estimate the turbulent dissipation rate in the sub-grid scale, to investigate the effect of the TVSS on the blood trauma. Detailed flow characteristics, such as the relative velocity vectors, the estimated TVSS levels and the Kolmogorov length scales, are analyzed in three impeller phases at three constant flow rates (3 L/min, 5 L/min and 7 L/min). Over the measures range in this study, the maximum TVSS in the investigated RBP is lower than the reported critical value of stress. This study demonstrates that the large eddy PIV method is effective to evaluate the flow-dependent force on the cells. On the other hand, it is found that the TVSS is highly dependent on the flow behavior. Under severe off-design conditions, the complex flow characteristics, such as the flow separation and the vortical structures, will increase the TVSS. Thus, in order to reduce the hemolysis in the RBPs, the flow disturbance, induced by the departure of the incidence angle, should be avoided during the design of the RBPs.
基金The author(s)disclosed receipt of the following financial support for the research,authorship,and/or publication of this article:This work was funded by National Institutes of Health(Grant Numbers:R01HL118372,R01HL124170,R01HL131750,and R01HL141817)This publication was made possible by the University of Maryland Baltimore Institute for Clinical and Translational Research(ICTR)which is funded in part by Grant Number TL1 TR003100 from the National Center for Advancing Translational Sciences(NCATS)a component of the National Institutes of Health(NIH),and NIH Roadmap for Medical Research.Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the University of Maryland Baltimore ICTR,NCATS or NIH.
文摘Centrifugal blood pumps have become popular for adult extracorporeal membrane oxygenation(ECMO)due to their superior blood handling and reduced thrombosis risk featured by their secondary flow paths that avoid stagnant areas.However,the high rotational speed within a centrifugal blood pump can introduce high shear stress,causing a significant shear-induced hemolysis rate.The Revolution pump,the Rotaflow pump,and the CentriMag pump are three of the leading centrifugal blood pumps on the market.Although many experimental and computational studies have focused on evaluating the hydraulic and hemolytic performances of the Rotaflow and CentriMag pumps,there are few on the Revolution pump.Furthermore,a thorough direct comparison of these three pumps'flow characteristics and hemolysis is not available.In this study,we conducted a computational and experimental analysis to compare the hemolytic performances of the Revolution,Rotaflow,and CentriMag pumps operating under a clinically relevant condition,i.e.,the blood flow rate of 5 L/min and pump pressure head of 350 mmHg,for adult ECMO support.In silico simulations were used to characterize the shear stress distributions and predict the hemolysis index,while in vitro blood loop studies experimentally determined hemolysis performance.Comparative simulation results and experimental data demonstrated that the CentriMag pump caused the lowest hemolysis while the Revolution pump generated the highest hemolysis.
文摘BACKGROUND： Ultraviolet blood irradiation and oxygenation （UBIO） has obtained better clinical effect in treating acute cerebral infarction, but the mechanism underlying this effect remains unclear. OBJECTIVE： To observe the effect of UBIO on the nerve function and activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase activities on the red blood cell （RBC） membrane of patients with acute cerebral infarction. DESIGN： A randomized and controlled study.SETTING： Department of Neurology, Xiangfan Central Hospital.PARTICIPANTS： From January 2000 to December 2001, excluding those above 70 years old, 58 cases of 700 patients with acute cerebral infarction admitted in the Department of Neurology, Xiangfan Central Hospital, were recruited and divided into two groups according to the random number table： UBIO treated group （n=28）, including 17 males and 11 females, aged 40-68 years; and control group （n=30）, including 20 males and 10 females, aged 44-69 years. All the patients agreed to participate in the therapeutic program and detected items. The general informations were comparable without obvious differences between the two groups （P 〉 0.05）.METHODS： ① The patients in both groups received routine treatments, besides, those in the UBIO treated group were given UBIO treatment by using the XL-200 type therapeutic apparatus produced in Shijiazhuang, whose ultraviolet wave was set at 253.7 nm with the energy density of 0.568 J/m^2 per second, UBIO treatment started from the second day after admission, once every other day, with a single course consisting of 5-7 treatments. ② In the UBIO treated group, the venous blood was sampled before and after the first, third and the completion of the treatment course respectively, the venous blood was taken at each corresponding time point in the control group. After centrifugation of the blood at 10 000 rounds per minute, the RBC membrane was separated and then the activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase were detected by means of phosphorus determination.③ The nerve function was scored before and after treatment in both groups with European stroke scale, which included 13 items, the total score was 0-100 points, the higher the score, the better the nerve function. MAIN OUTCOME MEASURES ：①Score of European stroke scale before and after treatment in both groups.② Comparison of the activities of K^＋-Na^＋-ATPase and Ca2^＋-Mg2^＋-ATPase on RBC membrane between the two groups before treatment and after the first, third and the completion of the treatment. RESULTS： All the 58 patients with cerebral infarction were involved in the analysis of results.① The score of European stroke scale had no obvious difference between the two groups [（49.31±11.48）, （50.58±12.63）, P 〉 0.05], and it was obviously higher in the UBIO treated group than in the control group after treatment [84.66±13.75）, （77.05±11.17）, P 〈 0.05].②The activity of K^＋-Na^＋-ATPase on RBC membrane in the UBIO treated group was significantly increased after the first and third treatment as compared with before treatment [（31.56±19.25）, （27.64±15.83）, （17.67±13.83）, P 〈 0.01], it was still higher after the completion of the treatment than before treatment without obvious difference [（20.86±14.53）, P 〉 0.05]. After the first and third treatment, it was obviously higher in the UBIO treated group than in the control group [19.31±11.88）, （17.44±10.42）, P 〈 0.01]. ③ In the UBIO treated group, Ca2^＋-Mg2^＋-ATPase activity on RBC membrane significantly increased after the first treatment and remained higher than the pre-treatment level throughout the treatment [（27.49±14.72）, （17.41±4.82）, P 〈 0.01]. The activity of Ca2^＋-Mg2^＋-ATPase on RBC membrane was markedly higher in the UBIO treated group than in the control group after after the first, third and the completion of treatment respectively [（24.83±12.88）, （17.70±5.69）; （28.08±13.44）, （16.32±5.29）; （17.42±6.04）, P〈 0.05-0.01]. CONCLUSION： The effect of UBIO treatment against acute cerebral infarction may be mediated by the increased K^＋-Na^＋ ATPase and Ca2^＋-Mg2^＋-ATPase activities on RBC membrane, which enhances the RBC transformation ability so as to lower RBC aggregation and correct high blood viscosity.
