自由基清除剂对体外冲击波碎石术肾损伤保护作用的动物实验研究

目的;探讨自由基清除剂古拉定在体外冲击波碎石术（ESWL）肾损伤中的保护作用。方法：选用24只2．5－3．0kg的大白兔,制备单肾模型（切除右肾,左肾上下极各夹银夹1只起定位作用）。随机选12只作为对照,ESWL前肌注生理盐水5ml。治疗组12只有ESWL前1h肌注古拉定,剂量300mg/kg体重。二组分别于ESWL前1d,后1,4,7d取血,尿标本。血标本检测过氧化物歧化酶（SOD）,丙二醛（MDA）值,尿标本检测β2－MG。两组于ESWL后第7天各处死10只,取左肾制备组织切片作光镜和电镜检查。结果：治疗组术后第1,4天血,SOD降低幅度和MDA升高幅度均明显低于对照组。光镜和电镜观察治疗组肾损伤病理变化较对照组轻。结论：在ESWL过程中存在氧自由基对肾脏损伤,加用外源性氧自由基清除剂可有效抑制这种损伤,从而对受治肾起到保护作用。     

新型可回收下腔静脉滤器的体外实验研究

目的通过建立体外模型,评估新型可回收下腔静脉滤器的滤过效果及稳定性。方法在体外建立下腔静脉模型,在不同管径、不同大小栓子及不同位置上分别评价滤器的稳定性及对栓子的捕获能力,并与Recovery可回收滤器进行对比。用牛血管重复实验,观察新型滤器滤过效果及稳定性。结果在体外下腔静脉模型中,新型可回收滤器对直径为2、3、5 mm的栓子滤过率分别为91.50%、96.50%和99.50%,管径为21、28 mm时滤过率为别为98.00%、93.67%,水平及垂直条件下栓子滤过率为94.33%、97.33%,总体滤过率为95.83%。Recovery可回收滤器在以上条件下的滤过率分别为81.00%,91.00%,95.00%;92.33%,85.67%及87.67%,90.33%,总体滤过率为89.00%。用牛血管取代硅胶管后,新型滤器在不同条件下的滤过率分别为88.50%,94.00%,98.00%;94.67%,92.33%及91.33%,95.67%,总体滤过率为93.50%。在实验过程中,两种滤器均未发现明显移位及偏斜现象。结论新型可回收下腔静脉滤器滤过效果及稳定性可靠,体外实验滤过效果优于Recovery滤器。     

体外膜肺氧合过程中心脏顿抑的动物实验

随着医学和科学技术的进展 ,体外膜肺氧合 (ＥＣＭＯ)成为治疗的有效手段之一。ＥＣＭＯ大量应用的过程中发现不少问题需探讨 ,心脏顿抑 (ｃａｒｄｉａｃｓｔｕｎ)就是其中之一〔1,2〕。我们的实验拟探讨心脏顿抑的可能机制。材料和方法　杂种犬 13条 (解放军总医院动物中心提供 ) ,体重 13～ 2 6ｋｇ。 2 5 %硫贲妥钠静脉麻醉 ,气管插管 ,呼吸机辅助呼吸。随机分 3组 :Ａ组为ＥＣＭＯ加冠状动脉 (冠脉 )结扎再灌注组 ,犬 7条 ,正中切口 ,建立右心房 主动脉径路ＥＣＭＯ转流 ,流量每分钟 10 0ｍｌ/ｋｇ ,灌注平均压 97 5ｍｍＨｇ(1ｍｍＨｇ…     

体外扩增的脐血细胞移植于BALB/C小鼠的实验研究

目的　探讨经体外扩增的脐血造血细胞对小鼠造血重建功能的影响 ,寻求脐血用于成人移植的可行方法。方法　将经致死剂量γ射线照射后的BALB/C小鼠 ,随机分为 4组 ,每组 10只。A组 :每只移植 2 .5× 10 6个新鲜脐血细胞 ;B组 :每只分别移植 1.2 5× 10 6个新鲜脐血细胞和 1.2 5×10 6个扩增培养 1周的脐血细胞 ;C组 :每只移植 2 .5× 10 6个扩增培养 1周的脐血细胞 ;D组 :每只仅输注 0 .5ml生理盐水。比较各组造血重建的差别。结果　在脐血细胞移植后第 13d ,A组存活 5只(5 0 % ) ,B组 8只 (80 % ) ,C组 6只 (6 0 % ) ,D组全部死亡。B组小鼠的死亡率最低。脐血细胞移植后 14d ,小鼠的WBC已开始回升 ,B组与C组的恢复明显较A组快 ,P <0 .0 5。结论　混合移植新鲜的和体外培养 1周的脐血造血细胞 ,可能是脐血移植的较好办法。     

体外冲击波碎石术对犬肾远期影响的实验研究

为了进一步了解体外冲击波碎石术（ＥＳＷＬ）对肾脏的远期影响，观察了２１只犬在ＥＳＷＬ后１、３、６及１２个月肾的肉眼、光镜和电镜的形态。结果显示：ＥＳＷＬ后１、３个月主要是肾小管的改变，但ＥＳＷＬ后６、１２个月时肾小管的病理改变不明显，而肾间质及肾小球的病理变化却逐渐明显，特别是肾小球系膜细胞胞浆中散在分布的肾素颗粒，表明ＥＳＷＬ后出现的高血压可能与所谓的“ｐａｇｅｋｉｄｎｅｙ效应”有关。     

体外冲击波碎石后结石高复发原因的实验研究

目的　探讨上尿路结石体外冲击波碎石 (ESWL)术后结石高复发的原因。　方法　构建羊肾盂结石动物模型 ,对模型动物行ESWL ,分期观察羊肾并行组织形态学检查。　结果　碎石后1周肾盂粘膜均有不同程度的损伤 ,粘膜内有结石微小颗粒嵌入 ,肾小盏内有弥散的小结石颗粒嵌入 ;2周后肾盂粘膜开始修复 ,4周基本恢复正常 ,但粘膜内嵌入的微小结石仍然存在 ,且周围出现纤维化包裹。　结论　ESWL术后结石复发与碎石所产生的微小颗粒粘膜嵌入肾盏及粘膜损伤有关。     

乳化异氟烷的溶血实验

目的 通过长期毒性研究来评价乳化异氟烷的溶血性.方法 健康SD大鼠100只,雌雄各半,体重100～160 g,6周龄,随机分为5组(n=20):对照组经尾静脉注射生理盐水3 ml/kg;溶媒组静脉注射30%脂肪乳3 ml/kg;乳化异氟烷高、中、低剂量组分别静脉注射乳化异氟烷132、108和84mg/kg;健康Beagle犬18只,雌雄各半,体重7.4～8.8 ks,7月龄,随机分为3组(n=6):对照组经前臂头静脉注射生理盐水2 ml/kg;溶媒组静脉注射30%脂肪乳2 ml/kg;乳化异氟烷组静脉注射乳化异氟烷135 mg/kg.所有动物每天给药1次,连续30 d(给药期).给药期结束时各组随机取半数动物,计数全血红细胞和网织红细胞,测定血红蛋白和总胆红素浓度,观察脾和肾组织病理学结果,Beagle犬行骨髓细胞学检查,各组剩余动物继续观察2周后(恢复期结束后)重复上述实验.结果 与对照组比较,乳化异氟烷高剂量组SD大鼠恢复期结束后全血红细胞计数降低(P<0.05),其余各指标差异无统计学意义(P0.05);各组Beagle犬给药期和恢复期结束后各指标差异均无统计学意义(P0.05);SD大鼠和Beagle犬脾和肾组织病理学结果未见异常,Beagle犬骨髓细胞学检查未见异常.结论 长期毒性研究时乳化异氧烷未引起大鼠和犬溶血反应.     

溶血卵磷脂开放胰腺炎大鼠血脑屏障的实验研究

目的:探讨胰腺炎时胰酶的作用产物之一溶血卵磷脂(LPC)对胰腺炎大鼠血脑屏障(BBB)通透性的影响。方法:首先将SD大鼠用Aho HJ法制成急性水肿型胰腺炎模型,随后实验组从大鼠的尾静脉注入LPC;对照组1在制成胰腺炎模型后从尾静脉注入生理盐水;对照组2为非手术组,单纯对其进行尾静脉注入LPC。其后7～10 d应用辣根过氧化物酶-二氨基联苯胺(HRP-DAB)显色法检测3组大鼠BBB的通透性,同时应用马根维显行磁共振造影检查其BBB的通透性。结果:HRP-DAB法显示实验组大鼠的BBB通透性明显升高,对照组BBB升高不明显,具有统计学差异;实验组大鼠表现为HRP局部血管外渗出;磁共振检查显示实验组及对照组大鼠BBB均无开放。结论:LPC能开放胰腺炎大鼠的BBB。     

体外脂肪细胞培养的实验研究

脂肪细胞属终末细胞，体外培养状态下是否可增殖，多数人持怀疑态度。我们在参考许多国外学者的经验基础上，采用密度梯度法分离脂肪细胞，ＤＭＥＭ和Ｆ１２混合培养基培养，同时加入糖皮质激素，胰岛素和碱性成纤维生长因子等促脂肪生长中因子，使脂肪细胞体外培养获得成功。     

ESWL对肾,输尿管影响的动物实验及临床观察

动物实验分为幼兔ＥＳＷＬ组、对照组及成年兔ＥＳＷＬ组，于ＥＳＷＬ后２４ｈ及３个月，分别观察分肾功能，肾生长发育，分肾静脉血及外周血肾素水平（ＰＲＡ）的变化。结果２４ｈ后冲击侧肾功能下降。３个月后肾功能已恢复，肾生长发育不受影响，冲击侧肾静脉血及外周血ＰＲＡ与对照组及未冲击侧相比未发现升高，肾内有灶性纤维化等改变，其中１只幼兔冲击肾发生萎缩，广泛纤维化。临床观察１６９２例ＥＳＷＬ患者中有３例输尿管结石ＥＳＷＬ后肾积水加重，血肌酐升高，３例冲击肾发生萎缩，其中１例功能丧失，１例伴肾周巨大血肿。认为一般情况下ＥＳＷＬ的危害不大，但个别情况可发生肾萎缩、功能丧失，故行ＥＳＷＬ时仍应谨慎为妥。     

Does Hematocrit Affect In Vitro Hemolysis Test Results? Preliminary Study with Baylor/NASA Prototype Axial Flow Pump

Abstract: The effect of hematocrit (Ht) on in vitro hemolysis test results (i. e., index of hemolysis) was evaluated using a Baylor/NASA prototype axial flow pump. Red blood cell suspensions of six different Ht (5, 10, 15, 20, 30, 40%; n = 30) were prepared and used for this evaluation. The pump was operated for 60 min under 5 L/min flow conditions, and blood samples were taken every 10 min to measure plasma free hemoglobin levels. The normalized index of hemolysis (NIH) was calculated using the regression line slope between time and plasma free hemoglobin level, and relationships between NIH and Ht or hemoglobin (Hb) were checked. NIH and Ht had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976, and NIH and Hb had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976. To reduce the effect of Ht, NIH/Ht was pro posed and compared with a modified index of hemolysis (MIH), which was normalized by the Hb level of blood. NIH/Ht and MIH had a poor correlation with Ht (coefficient of fit, 0.608) and Hb (coefficient of fit, 0.577), respectively. When blood that has a wide range of Ht or Hb values is used for in vitro hemolysis tests, NIH/Ht is suggested for use as an index of hemolysis to evaluate the hemolysis characteristics of rotary blood pumps because MIH has no dimension and it requires Hb values. In contrast, NIH/Ht has a dimension of g/100 L, which is quite understandable, and it does not require measurement of Hb levels of blood; it is therefore cost–effective.     

Relationship Between Pump Speed Design and Hemolysis in an Axial Flow Blood Pump

Abstract
In an attempt to reduce the hemolysis caused by axial flow blood pumps, we investigated whether the specific speed should be kept within the standard engineering range or whether pump speed should be minimized, thus making the specific speed beyond the standard range. Four pumps with 11.8 mm diameter impellers were designed to accommodate a flow of 5 L/min and a head of 100 mm Hg. The pumps were tested at 4 speeds: A, 14,000; B, 18,000; C, 22,000; and D, 26,000 rpm. Pump performance data were obtained, and the maximum point of total pump efficiency was found for each pump. The maximum efficiencies were A, 50%; B, 58%; C, 52%; and D, 53%. The specific speed of each pump recorded at the maximum efficiency point was calculated as A, 899; B, 954; C, 1,218; and D, 1,951 rpm. Hemolytic tests were performed with fresh goat blood in a closed, mock-loop circuit. Hemolytic indexes were A, 0.036; B, 0.22; C, 0.35; and D, 0.66. We have concluded that decreased hemolysis is correlated with a lower pump speed and that the specific speed for the lowest pump speed is less than the standard range. Having a specific speed outside the standard range was not correlated with reduced total pump efficiency.     

Development of an Axial Flow Ventricular Assist Device: In Vitro and In Vivo Evaluation

Abstract: A collaborative effort between Baylor College of Medicine and NASA/Johnson Space Center is underway to develop an axial flow ventricular assist device (VAD). We evaluated inducer/impeller component designs in a series of in vitro hemolysis tests. As a result of computational fluid dynamic analysis, a flow inducer was added to the front of the pump impeller. According to the surface pressure distribution, the flow inducer blades were connected to the impeller long blades. This modification eliminated high negative pressure areas at the leading edge of the impeller. Comparative studies were performed between inducer blade sections that flowed smoothly into the impeller blades (continuous blades) and those that formed discrete separate pumping sections (discontinuous blades). The inducer/impeller with continuous blades showed significantly (p < 0.003) lower hemolysis with a normalized index of hemolysis (NIH) of 0.018 ±< 0.007 g/100 L (n = 3), compared with the discontinuous model, which demonstrated an NIH of 0.050 ± 0.007 g/100 L (n = 3). The continuous blade model was evaluated in vivo for 2 days with no problems. One of the pumps evaluated ran for 5 days in vivo although thrombus formation was recognized on the flow straightener and the inducer/impeller. As a result of this study, the pump material was changed from polyether polyurethane to polycarbonate. The fabrication method was also changed to a computer numerically controlled (CNC) milling process with a final vapor polish. These changes resulted in an NIH of 0.0029 ± 0.0009 g/100 L (n = 4). which is a significant (p < .0001) value 6 times less than that of the previous model. This model was used for in vivo studies and achieved 9 days of operation with a sufficient flow between 3.6 and 4.7 L/min against 80 to 100 mm Hg mean arterial pressure. Plasma free hemoglobin levels remained at 2–3 mg/dl with a hematocrit of 20%.     

The Effect of the Impeller-Driver Magnetic Coupling Distance on Hemolysis in a Compact Centrifugal Pump

Abstract: Blood trauma is one of the important performance parameters of centrifugal pumps. To investigate the blood trauma induced by these pumps, in vitro hemolysis tests have become an important procedure and are increasingly used for pump development and comparisons. The Baylor compact eccentric inlet port (C1E) centrifugal blood pump was developed as a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump (CPB). The Baylor C1E pump incorporates a seal-less design with a blood stagnation-free structure. This pump can provide flows of 5 L/min against 350 mm Hg of total pressure head at 2,600 revolutions per minute. The pump impeller is magnetically coupled to the driver magnet in a seal-less manner. The latest hemolysis study revealed that hemolysis may be affected by the gap distance between the driver and the impeller magnet. The purpose of this study was to verify the effect of the magnetic coupling distance on the normalized index of hemolysis (NIH) with the C1E model and to obtain an optimal gap distance. The NIH value was clearly decreased by alteration of the magnetic coupling distance from 7.7 to 9.7 mm in CPB and left ventricular assist device (LVAD) conditions. The NIH, when using the pump as an LVAD condition, was reduced to a level of 0.0056 from 0.095 when the magnetic coupling distance was extended. The same results were also obtained when the pumps were used in a CPB condition. The magnetic coupling distance is an important factor for the C1E model in terms of hemolysis. Different coupling forces effect the bearings and impeller stability. These results suggest that an optimal driving condition with a proper magnetic coupling and an optimal force between the impeller and driver is necessary to develop an atraumatic centrifugal pump.     

The Need for Standardizing the Index of Hemolysis

Abstract: Hemolysis is one of the most important performance parameters of blood pumps. However, comparative in vitro evaluation of the reported hemolysis effect is difficult owing to the lack of uniformity in the test methods used. Currently, three types of formulas are generally accepted and widely used for the index of hemolysis: the traditionally used index of hemolysis (defined as grams of plasma free hemoglobin released per 100 L of blood pumped); the normalized index of hemolysis (normalized by hematocrit); and the modified index of hemolysis (taking into account not only hematocrit but also hemoglobin). In addition, the tested blood conditions are often not indicated in the reports. To address this confusing situation, all three indices of hemolysis were routinely derived in our laboratory. To avoid further confusion, the tested blood conditions and test loop were defined in each study in our laboratory. If we limit the acceptable range of hemoglobin in human blood, the normalized index of hemolysis is sufficient. Furthermore, using milligrams as the unit of expression would be easier and reasonable for comparing the less hemolytic blood pumps, such as the centrifugal pumps that are currently available clinically. We would like to propose this value of a normalized index of hemolysis in milligrams as the most useful formula for the index of hemolysis in the assessment of various types of rotary blood pumps.     

Experimental Investigation of Pulsatility Effect on the Deformability and Hemolysis of Blood Cells

In this study, we investigated the differences between pulsatile cardiopulmonary bypass (CPB) procedure and nonpulsatile CPB procedure in terms of their effects on hemolysis and deformability of red blood cells (RBCs) under various shear stress conditions. In order to research the effects on hemolysis and deformability, four parameters—free hemoglobin (fHb) concentration, normalized index of hemolysis (NIH), deformability index (DI) of RBCs, and elongation index of RBCs—have been deeply investigated. For these investigations, two randomly assigned adult mongrel dog groups—nonpulsatile group (NP, n = 6) and pulsatile group (P, n = 6)—were examined. According to our results, both types of perfusion did not show any statistical differences in terms of the concentrations of fHb as well as NIH. In addition, there were no significant differences in RBC deformability between perfusion types within an operation time of 3 h. Therefore, our studies suggest that pulsatile perfusion has no significant difference from nonpulsatile perfusion in terms of hemolysis and deformability of RBCs.     

Mechanical Blood Traumatization by Tubing and Throttles in In Vitro Pump Tests: Experimental Results and Implications for Hemolysis Theory

Abstract: Blood has become essential as a test fluid to evaluate hemolysis and biocompatibility of blood pumps in vitro. The blood is usually pumped from a blood bag into a circuit against elevated pressure. A throttle or a length of tubing is used to produce the pressure head. Blood damage caused by the shear stress in these pressure-reducing devices should be minimal. It is not known whether the high but short-lasting shear stress in a throttle is more or less damaging to the blood than the low but long-lasting stress in tubing. In this study, throttles (width 11 mm, minimal height 0.9 mm, length 30 mm; shear stress = 136 N/m² lasting for 3.23 ms); and tubing (inner diameter 9.5 mm, length 4.5 m, shear stress = 4.5 N/m² lasting for 3.5 s) were compared at a flow of 5 L/min and a pressure drop of 150 mm Hg. Experiments (n = 10) with bovine blood were performed in two parallel setups using Bio-Medicus pumps BP80. Free hemoglobin in plasma (fHb) and thromboxane B₂ (TXB₂) were measured. After 6 h, the fHb increase was 31.9 ± 19.1 mg% for the throttle setup and 32.3 ± 16.2 for the tubing setup. The TXB₂ release was 296 ± 70 and 305 ± 54 pg/0.1 ml respectively after 4 h. In summary, no significant differences between the two setups for either fHb or TXB₂ could be detected. So the use of a throttle, which requires far less priming volume and a smaller blood-contacting surface while also offering a wider range of adjustment, seems preferable. Furthermore, in contrast to some other in vitro studies, these results strongly indicate that blood is quite insensitive to high shear stress exposure in the millisecond range even if repetitively applied.     

In Vitro Performance of a Centrifugal, a Mixed Flow, and an Axial Flow Blood Pump

Abstract We specially devised 3 types of turbo pumps, a centrifugal pump (CFP), a mixed flow pump (MFP), and an axial flow pump (AFP), and analyzed their in vitro performance. The common structural design elements were an impeller diameter of 20 mm and sealless magnet couple driving. In vitro tests were carried out using heparinized fresh bovine blood. The hemolysis was comprehensively evaluated at 7–16 points by changing the flow rate and pressure head (mapping of hemolytic property). The maximum efficiency (motor output to pump output) was 44.9% at 7,000 rpm, 3.17 L/min, 191 mm Hg in the CFP; 66.3% at 7,000 rpm, 6.9 L/min, 136 mm Hg in the MFP; and 20.6% at 9,000 rpm, 5.54 L/min, 74 mm Hg in the AFP, respectively. The minimum normalized index of hemolysis (NIH) (g/100 L) was 0.038 at 5,000 rpm, 4.60 L/min, 38 mm Hg in the CFP; 0.010 at 7,000 rpm, 8.22 L/min, 100 mm Hg in the MFP; and 0.033 at 7,000 rpm, 2.84 L/min, 48 mm Hg in the AFP, respectively. The best efficiency and NIH were achieved in the MFP.     

Modification of a Pivot Bearing System on a Compact Centrifugal Pump

Abstract: The pivot bearing centrifugal blood pump was developed as a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. This pivot bearing supported centrifugal pump with an eccentric port (C1E) incorporates a seal-less design with a blood stagnation-free structure. This pump can provide flows of 12 L/min against 650 mm Hg total pressure head at 3,600 rpm, and in a CPB condition 5 L/min against 350 mm Hg total pressure head at 2,600 rpm. Very recently, the pivot bearing system was modified to obtain a stable and smooth spinning movement. The material of the female pivot was changed from ceramic to polyethylene. Three kinds of bearings were tested simultaneously with bovine blood in two types of in vitro circuits to determine the blood damage from the bearings. Pressure differences across the pump (total head pressure, A/¹) of 140 mm Hg (n = 12) and 330 mm Hg (n = 12) were examined. The normalized index of hemolysis (NIH) was slightly higher in a ball bearing (BB) pump than in a polyethylene bearing (PB) pump and statistically higher than the BioMedicus Pump (BP-80) on ΔP of 140 mm Hg. When the ΔP was at 330 mm Hg, a comparison between the three types of pumps revealed no difference in NIH. In addition, the primary vane of the impeller was redesigned to obtain an atraumatic structure. In the second study (n = 14), there was no difference in the NIH between BP-80 and the current model when the A/⁵ was 300 mm Hg (0.019 ± 0.002 vs. 0.027 ± 0.006, p = 0.3) and/or when the A/¹ was 100 mm Hg (0.0008 ± 0.0001 vs. 0.0014 ± 0.0002, p = 0.07). The modified pivot bearing had an improved spinning condition and no change in hemolysis. A proper selection of pivot bearing materials is important to develop an atraumatic centrifugal pump. The modification of the bearing system and redesign of the vane enabled a compact centrifugal pump to become a reality.     

Controller for an Axial Flow Blood Pump

Abstract: A rotary blood pump inherently provides only one noninvasive "observable'" parameter (motor current) and allows for only one "controllable" parameter (pump speed). To maintain the systemic circulation properly, the pump speed must be controlled to sustain appropriate outlet Hows and perfusion pressure while preventing pulmonary damage caused by extremes in preload. Steady-state data were collected at repeated intervals during chronic trials of the Nimbus AxiPump (Nimbus, Inc., Rancho Cordova, California, U.S.A.) in sheep (n = 7) and calves (n = 12). For each data set, the pump speed was increased at increments of 500 rpm until left ventricular and left atrial emptying was observed by left atrial pressure diminishing to zero. The effect of decreasing preload was evaluated perioperatively by inferior vena cava occlusion at a constant pump speed. Fourier analysis established a relationship between changes in the pump preload and the power spectra of the pump current waveform. Based on these results, a control method was devised to avoid ventricular collapse and maintain the preload within a physiologic range. The objective of this controller is the minimization of the second and third harmonic of the periodic current waveform. This method is intended to provide a noninvasive regulation of the pump by eliminating the need for extraneous transducers.