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Objective:The hemolytic prediction model of the axial flow impeller blood pump is carried out by using a computational fluid dynamics(CFD) multiphase flow model.Methods:The hydrodynamic performance of the pump and the flow field in the pump, and the shear stress distribution are analyzed. A hemolytic prediction model based on the shear stress is built based on the calculation results. Hemolysis tests in vitro were performed 6 times with fresh bovine blood. At each time, the flow of the ventricular assist device(VAD) is 5 L/min and the outflow tract pressure is 100 mmHg(13.3kPa). According to the tests, the plasma free hemoglobin(FHB) content and the hematocrit(HCT) are measured every half hour. At the end of each experiment Normal Index of Hemolysis(NIH) is calculated.Results:The average of NIH is 0.0055 g/100L, almost identical with that obtained from the hemolytic prediction model.Conclusion:Multiphase flow model can be used for quantitative predictions of the hemolytic behavior of a VAD. This method can be applied in the selection stage of a blood pump.
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Objective To establish a large animal ( sheep) model to serve the experiments of domestic pulsatile ventricular assist device.Methods Three small-tail Han-sheep were anesthetized and the vein access and artery access were achieved.The cardiopulmonary bypass was established through left thoracotomy.Ventricular fibrillation was induced. An hole was made in the apex of left ventricle and the apex cannulation was sutured to it.The aortic cannulation was su-tured to the descending aorta.The two cannulations were connected to the domestic pulsatile ventricular assist device ( DP-VAD) and the driver was turned on.The working of DPVAD and the conditions of the animals were observed.Results The DPVAD worked well and uni-directional blood flow was driven by positive and negative pressure.The left ventricle was unloaded and the blood pressure was raised up.Conclusion The establishment of sheep model of pulsatile ventrieular as-sist device may play important role for the research and development of DPVAD in our country.
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Objective To study the effects of improving elderly patients with bowel dysfunction after cardiopulmonary bypass.Methods Choose 54 elderly patients with CPB were randomly divided into tree groups:the control group and the Gln group and the Combination group,every group has 18 patients.Glutamine(Gln) at 0.4 g/kg was administrated to the patients in the Gln group and the combination group during the beginning at CPB and two days after the operation.Based on the Gln group,the patients of The Combination group were given the different oral Chinese medicine before and after operation,according to syndrome differentiation classification.Plasma endotoxin,IL-6 and DAO were measured before operation and at the endof operation and 24 h,48 h after operation.At the same time,we used German Siemens Company's X3000 Color Doppler machine to test every group of patients superior mesenteric artery.We tested before surgery,and one to two days after operation,from the starting point within 2cmof the superior mesenteric artery and the angle between the ultrasound beam flow was less than 60 °,the probe frequency was 3.5 MHz.The detection of hemodynamic indexes were EDV and PI.Results After the test,the plasma endotoxin and IL-6 levels and DAO levels of the Gln group were reduced than the Control group after cardiopulmonary bypass.The plasma endotoxin and IL-6 levels and DAO levels of the Combined gnup were decreased than the Gln group after cardiopulmonary bypass and one day after operation.Analyze superior mesenteric artery diastolic velocity (EDV)and pulsatility index (PI) by the Color Doppler.After operation,the EDV in the Gln group and the Combined grup were significantly higher than the control group,the Pl were lower than the control group.The parameters levels have significant difference after cardiopulmonary bypass and one day after operation(P ＜ 0.05 ).The Combined group was improved than the Gln group after cardiopulmonary bypass and one day after operation.According to the traditional Chinese medicine diagnosis,there were eighteen patients in the Combined group,including fifteen patients in type of deficiency of both qi and yin and three patients in type of fu-viscera syndnome.All of the patients have defecated within tree days after operation.In the type of deficiency of both qi and yin nine patients were cured and six were shown to be effective after operation.All the patients in type of fuviscera syndrome were cured.Conclusion N(2)-L-Alanyle-L-Glutmaine have protective effect on the intestinal mucosal barrier after CPB.Combined traditional Chinese Medicine preparation was more conducive to the intestinal function recovery of elderly patients after cartiopulmonary bypass.
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@#Objective To establish an animal model for implantable ventricular assist device. Methods Seven male calves, body weight 120 to 180 kg, were anesthetized and underwent surgical implantation through a left thoracotomy at the 4th intercostal space. The domestic-made implantable ventricular assist device (DIVAD) was implanted after cardiopulmonary bypass and induction of ventricular fibrillation. The major indexes of mechanical properties of the DIVAD are similar to those of imported devices. The DIVAD was 29.5 mm × 72 mm, with a total weight of 158 g. The maximal pump speed was 9000 rpm and the maximal pump flow was 8 L/min in in vitro experiment. A flow meter was incorporated into the pump. The DIVAD was constructed with an external controller, and the pump can be monitored and adjusted through it. The inflow cannula was positioned into the left ventricle and the outflow cannula was sutured to the descending aorta. The pump was run at 3,500 to 8,000 rpm. The cardiopulmonary bypass was weaned. The pump output and animal condition was continuously monitored. Heparin was administered to maintain the activated clotting time at 1.5 to 2 times its baseline value. Results All the seven calves weaned from cardiopulmonary bypass. The mean survival time is 20.28 hours with a range from 0.5 to more than 93 hours. Conclusion Calf is the right animal model for NIVAD implantation and there are some characteristics in its perioperative treatment. The establishment of this animal model may play important role for further improvement of NIVAD.