燃烧加热污染空气对超燃冲压发动机性能影响研究

针对燃烧加热地面试验设备存在的工质污染问题,采用数值模拟方法研究了燃烧加热污染空气对氢燃料超燃冲压发动机性能的影响。以飞行马赫数Ma=6.5,当量油气比ER=0.6为计算基准状态,分别对纯净空气和污染空气来流下氢燃料超燃冲压发动机的整机流场和性能进行了对比计算分析。燃烧化学反应模拟采用了改进的H₂/O₂七组分八方程模型,湍流模型为标准的 k-ε模型,并采用直连式燃烧室试验数据进行了数值方法的验证。研究结果表明:(1)相对于纯净空气来流,污染空气来流下的超燃冲压发动机推力和比冲均有所下降。(2)采用酒精燃烧加热器的前提下,来流参数匹配静温、静压、马赫数时,发动机性能与纯净空气来流下的结果最为接近,而匹配总温、总压、马赫数时相差最大。(3)来流参数匹配总焓、静压、马赫数的前提下,采用氢燃烧加热器时发动机性能与纯净空气来流下的结果最为接近,而采用甲烷燃烧加热器时相差最大。      

重力对FAIR序列肺灌注成像影响的研究

目的 用FAIR序列评价重力对MRI肺灌注血流分布的影响.资料与方法 对10例健康志愿者在仰卧位时,分别对5个冠状面FAIR图像的肺血流量(PBF)间进行分析.结果 在重力方向上存在灌注梯度,5个冠状面的PBF间的差异均有统计学意义(P<0.05),PBF由后至前是逐渐减小的.在非重力方向上,肺灌注不存在灌注梯度.右肺的回归系数是-4.98,左肺的回归系数是-5.16.结论 FAIR评价肺灌注在重力方向的灌注梯度是比较敏感的,可提高灌注缺损的检出率.     

Diagnostic accuracy of supine and prone thallium-201 stress myocardial perfusion single-photon emission computed tomography to detect coronary artery disease in inferior wall of left ventricle

OBJECTIVE: Prone thallium-201 ((201)Tl) myocardial perfusion single-photon emission computed tomography (SPECT) reduces false-positive rates when evaluating inferior wall abnormalities by minimizing diaphragmatic attenuation. The present study investigates the diagnostic validity of prone (201)Tl stress myocardial perfusion SPECT for detecting coronary artery disease in the inferior wall of the left ventricle in Japanese patients. METHODS: Of the 104 consecutive patients who underwent (201)Tl stress myocardial perfusion SPECT to diagnose coronary artery disease, we evaluated 46 who underwent image acquisition in both the supine and prone positions, and coronary angiography within 3 months thereafter. Images were acquired in the routine supine position immediately following (201)Tl (111 MBq) injection and 4 h following early acquisition. Images were acquired in the prone position only during the early phase following supine acquisition. We evaluated the SPECT images of the inferior half segments of the left ventricle using a five-point defect scoring system. According to the coronary angiographic findings, we investigated the diagnostic accuracy of stress-rest supine, stress supine, stress prone, and combined supine-prone images. Reduced uptake in the stress supine image of the combined images was considered as attenuation when uptake was normal in the prone image. RESULTS: The sensitivity of the stress-rest supine, stress supine, stress prone, and stress-combined supine-prone images was 77%, 86%, 55%, and 55%, and the specificity was 71%, 54%, 79%, and 83%, respectively. Diagnostic accuracy was the highest in stress-rest supine images. CONCLUSIONS: Prone images tended to improve the specificity of detecting coronary artery disease in the inferior wall, but not diagnostic accuracy compared with stress-rest supine images because of decreased sensitivity.     

急性脑梗死应用多模式CT指导下rt-PA静脉溶栓的疗效观察

目的:探讨多模式CT指导下的急性脑梗死rt-PA静脉溶栓的临床疗效.方法:将2015年2月~2016年2月间90例急性脑梗死患者根据治疗方法的不同分为观察组和对照组,观察组于治疗前及治疗后采用多模式CT检查,采用rt-PA静脉溶栓治疗,对照组采用奥扎格雷钠注射液+阿司匹林治疗.比较两组患者治疗后血管再通情况、神经功能改善情况及不良反应.结果:观察组血管再通率51.1%(23/45),显著高于对照组的26.7%(12/45.两组治疗后TIMI分级均显著改善,且观察组改善情况明显优于对照组.治疗后24h、7d及30d,两组NIHSS评分呈明显下降趋势,且观察组显著优于对照组.观察组共5例(11.1%)患者出现症状性脑出血,与对照组(4.4%)无统计学意义.结论:多模式CT指导下的急性脑梗死rt-PA静脉溶栓治疗能够明显改善患者血流灌注,促进神经功能恢复.     

Liver preservation with HTK: salutary effect of hypothermic aerobiosis by either gaseous oxygen or machine perfusion

The aim of the present study was to improve the viability of marginal livers from non-heart beating donors upon cold preservation using two different techniques for the provision of tissue aerobiosis. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein with 20 mL of heparinized Ringer's solution and 60 mL of histidine-tryptophan-ketoglutarate (HTK) preservation solution. Control livers were then stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to aerobic conditions by either insufflation of gaseous oxygen via the venous vascular system of the cold stored organ (VSOP) or pulsatile machine perfusion (MP) with oxygenated HTK at 5 mL/min at 4 degrees C. Superoxide dismutase (SOD) (7500 IU) was added to the last 10 mL of HTK in order to prevent adverse effects of high oxygen tensions at hypothermia. Viability of the livers was assessed upon isolated perfusion in vitro with oxygenated Krebs-Henseleit buffer at constant flow. VSOP or MP, both significantly improved vascular conductivity upon reperfusion as evaluated by portal venous pressure, reduced hepatic enzyme release and led to a rise in hepatic bile production upon reperfusion. Induction of apoptosis was also looked for in tissue homogenates by Western analysis for cleavage of poly(ADP-ribose)polymerase (PARP). Expression of cleaved PARP fragment could be found in reperfused control livers but also, though to a lesser extend, after VSOP or MP. In conclusion, provision of oxygen during cold preservation significantly contributes to improve organ viability upon reperfusion and must be regarded as a useful adjunct for marginal or pre-damaged livers. HTK has been shown for the first time to be also suitable for long-term MP preservation of the liver, but, as inferred from these data, simple insufflation of gaseous O2 may be considered a feasible alternative.     

亚甲蓝对感染性休克犬肠道灌注和氧合的影响

目的　研究鸟苷酸环化酶抑制药亚甲蓝对感染性休克犬肠道灌注和氧合的影响。方法　静脉注入内毒素诱导的 7只感染性休克犬模型 ,输注 0 9%氯化钠复苏后 15分钟内注入亚甲蓝2mg/kg。血流量仪测定基础、休克 1小时后、复苏后和亚甲蓝注入后 30分钟肠系膜上动脉血流量。分析动脉和肠系膜上静脉血气 ,计算肠道氧合。结果　犬感染性休克后 ,肠系膜上动脉 (肠道 )血流减少 6 1 8% (P <0 0 1) ,氧输送 (DO2 )减少 6 2 1% (P <0 0 1) ,氧摄取 (O2 extr)增加 2 3 5 %。复苏至肺动脉嵌压为 (12 1± 1 4 )mmHg后 ,肠道血流增加 5 4 6 % (P <0 0 1) ,DO2 增加 12 8% (P <0 0 1) ,O2 extr增加 2 0 9%。亚甲蓝注入后 ,肠道血流增加 19 4 % (P <0 0 1) ,DO2 则无明显变化 (P >0 0 5 ) ,O2 extr增加 14 8%。结论　感染性休克后肠道血流灌注减少 ,氧耗增加 ;液体复苏仅部分恢复肠道灌注 ;亚甲蓝增加肠道灌注和氧摄取     

贲门周围血管离断术前后肝硬化病人肝脏血流灌注的改变

目的：利用肝脏阻抗血流图探讨肝硬化门静脉高压症病人的肝脏血流灌注改变和贲门周围血管离断术对肝脏血流灌注的影响。方法：选取22例肝硬化门静脉高压症病人，分别在术前1周、术后2周检测肝血流阻抗改变，同时用Doppler检测门静脉血流动力学变化。结果：阻抗血流图表明，和对照XEG相比，门静脉高压症病人的肝动脉、门静脉向肝血流灌注明显下降，总肝灌注量降低；门静脉高压症病人术后门静脉向肝灌注增加，肝动态的向肝灌注无显著改变。Doppler测定表明门静脉高压症病人的门静脉直径增加，血流量增加，但血流速度无显著差别；术后门静脉血流动力学与术前无差别。结论：肝硬化病人肝动脉、门静脉向肝有效血流灌注都降低，肝脏总血流量下降；贲门周围血管离断术增加大部分病人的门静脉向肝血流灌注，但对肝动脉的向肝灌注无显著影响；肝脏阻抗血流图作为反映肝脏动态血流灌注的无创性检查，对于评价肝硬化病人的肝脏血流及评价手术对肝脏血流动力学的影响有一定的价值。     

硝酸甘油对移植犬肺的保护作用

目的评价硝酸甘油对犬肺的保护作用。方法将24只犬随机分为实验组和对照组两组,每组供、受体各6只。实验组用含硝酸甘油的低钾右旋糖酐(low potassium dextran,LPD)灌注液灌注供肺,对照组仅用LPD灌注液灌注供肺,留取供犬右肺继续于灌注液中保存至4h,修剪左肺作移植肺,两组受体犬均行左肺移植术。比较两组供体肺组织不同时间的髓过氧化酶(myeloperoxi-dase,MPO)活性、丙二醛(malondialdehyde,MDA)含量和湿/干重量比(W/D),比较两组受体犬移植前后不同时间肺血流动力学参数以及血气分析指标,并比较病理结果。结果与对照组相比,实验组肺组织灌注后各时间段的MPO活性、丙二醛含量均较低(均为P(0.05),两组W/D差异无统计学意义。实验组受体犬移植后的平均肺动脉压(mean pulmonary arterial pressure,MPAP)低于对照组而动脉血氧分压(PaO2)高于对照组(均为P(0.05)。移植后供肺肺组织的病理学结果显示,实验组肺组织水肿、炎性细胞浸润、损伤等病理变化较对照组减轻。结论在本实验条件下,在灌注液中加入硝酸甘油可以在犬肺移植过程中起到保护肺组织的作用。     

Evaluation of perfusion modes on vital organ recovery and thyroid hormone homeostasis in pediatric patients undergoing cardiopulmonary bypass

The objectives of this study were: (i) to evaluate the effects of perfusion modes (pulsatile vs. nonpulsatile) on vital organs recovery and (ii) to investigate the influences of two different perfusion modes on the homeostasis of thyroid hormones in pediatric patients undergoing cardiopulmonary bypass (CPB) procedures. Two hundred and eighty‐nine consecutive pediatric patients undergoing open heart surgery for repair of congenital heart disease were prospectively entered into the study and were randomly assigned to two groups: the pulsatile perfusion group (Group P, n = 208) and the nonpulsatile perfusion group (Group NP, n = 81). All patients received identical surgical, perfusional, and postoperative care. Study parameters included total drainage, mean urine output in the intensive care unit (ICU), intubation time, duration of ICU and hospital stay, the need for inotropic support, pre‐ and postoperative enzyme levels (ALT [alanine aminotransaminase] and AST [aspartate aminotransaminase]), c‐reactive protein, lactate, albumin, blood count (leukocytes, hematocrit, platelets), creatinine levels, and thyroid hormones (thyroid stimulating hormone [TSH], FT₃[free triiodothyronine], FT₄[free thyroxine]). All patients survived the perioperative and postoperative periods. There were no statistically significant differences in either preoperative or operative parameters between the two groups. Group P, compared to Group NP, required significantly less inotropic support, had a shorter intubation period, higher urine output in ICU, and shorter duration of ICU and hospital stay. Lower lactate levels and higher albumin levels were observed in Group P and there were no significant differences in creatinine, enzyme levels, blood counts, or drainage amounts between two groups. TSH, Total T₃, Total T₄, and FT₃, FT₄ levels were markedly reduced versus their preoperative values in both groups. FT₃ and FT₄ levels were reduced significantly further in the nonpulsatile group both during CPB and at 72 h postoperation. The results of this study confirm our opinion that pulsatile perfusion leads to better vital organ recovery and clinical outcomes in the early postoperative period as compared to nonpulsatile perfusion in pediatric patients undergoing CPB cardiac surgery. The plasma concentrations of thyroid hormones are dramatically reduced during and after CPB, but pulsatile perfusion seems to have a protective effect of thyroid hormone homeostasis compared to nonpulsatile perfusion.     

新型双球囊导管在经皮选择性隔离肝脏灌注化疗中的应用

目的探讨自制双球囊导管在经皮选择性肝脏隔离灌注化疗(PSIHP)中的应用效果。方法实验猪12头,利用介入放射学方法进行双球囊导管选择性隔离肝脏灌注化疗结合血液灌流。化疗药物选用5-FU。比较灌注及未灌注区域肝细胞形态和凋亡指数。结果灌注区域肝细胞损伤明显,肝细胞凋亡指数(51.82%±5.34%)明显高于未灌注区域肝细胞凋亡指数(4.12%±0.84%)(P<0.01)。结论自制新型双球囊导管能有效隔离肝脏,对未灌注区域肝组织有良好的保护作用,是一种理想的隔离肝脏灌注化疗的球囊导管。