Is Avoidance of Air Contact Necessary for the In Vitro Evaluation of Thrombogenicity in Mechanical Circulatory Assist Devices?

An effective in vitro protocol for the investigation of thrombogenicity can provide many advantages in the development of mechanical circulatory assist devices. Strict avoidance of air contact with blood recently was proposed for reliable in vitro evaluation. This study was performed to confirm the necessity of avoidance of air contact for the in vitro test of thrombogenicity in a rotary pump. Two sets of mock circuits with the same rotary blood pumps, reservoirs, and connecting tubes were made. In one system, blood came in contact with air while the other did not. The test blood was heparinized at the dose of 1 IU per 1 ml of blood. The tests were terminated at an activated coagulation time of 1.5 times the control value. The levels of hematocrit, platelet, factors VIII and XII, fibrinogen, thromboxane B2, and plasma-free hemoglobin were measured during the procedures. After the experiments, the thrombi formed were observed, measured, and compared with those formed in in vivo circumstances. The tests were repeated 12 times. There were no statistically significant differences between the 2 groups in hematologic parameters and the amounts of thrombi formed. The thrombi observed in both groups showed the same pathologic findings as those formed in vivo with the exception of intermittent multiple air bubbles found in thrombi of the air-contact group. In conclusion, the effect of air contact in the in vitro investigation of thrombogenicity was negligible while the proposed in vitro test models of thrombogenesis in the mechanical circulatory assist device proved to be reliable.     

Tracheal Transplantation: Superior and Inferior Thyroid Artery Perfusion Territory

Objective: To determine the perfusion territories of the superior and inferior thyroid arteries in humans. Tracheal transplantation is a potential option for management of long-segment tracheal stenosis. However, the maximum length of vascularized trachea that can be reliably transplanted has not been established. Study Design: The tracheal vascular territory of individual superior and inferior thyroid arteries was determined separately in 10 humans postmortem. Methods: India ink was infused unilaterally under controlled pressure into the superior (n = 5) and inferior (n = 5) thyroid arteries of cadaveric tracheas. Tracheas were sectioned longitudinally and the caudalmost extent of mucosal dye staining was determined via microscopic assessment. Results: The tracheal perfusion territory of the superior thyroid artery was two to five rings (1.7 ± 0.5 cm) and the inferior thyroid artery, nine to 13 rings (6.5 ± 1.1 cm). In both cases, the tracheal mucosa on the contralateral side was stained to the same caudal level. Conclusions: The inferior thyroid artery was shown to perfuse the trachea maximally to the 13th ring (8.1 cm). As such, the unilateral inferior thyroid artery would serve as a suitable vascular component for long-segment tracheal transplantation in humans.     

Risk factors for respiratory syncytial virus associated apnoea

Respiratory syncytial virus (RSV) infections are characterized by upper or lower respiratory tract symptoms including bronchiolitis and pneumonia. Apnoea may be the first sign of disease in children with RSV infection. The aims of this study were the identification of independent risk factors for RSV associated apnoea and the prediction of the risk for mechanical ventilation in children with RSV associated apnoea. Medical records of children younger than 12 months of age admitted with RSV infection between 1992 and 1995 to the Sophia Children's Hospital, were reviewed. Demographic parameters, clinical features and laboratory parameters (SaO₂, pCO₂ and pH) were obtained upon admission and during hospitalization. Children with and without apnoea were compared using univariate and multivariate logistic and linear regression analysis. One hundred and eighty-five patients with RSV infection were admitted of whom 38 (21%) presented with apnoea. Patients with apnoea were significantly younger, had a significantly lower temperature, higher pCO₂ and lower pH and had on chest radiographs also more signs of atelectasis. The number of patients admitted to the ICU because of mechanical ventilation and oxygen administration was significantly higher in children with RSV associated apnoea. Apnoea at admission was a strong predictor for recurrent apnoea. The relative risk for mechanical ventilation increased with the number of episodes of apnoea: 2.4 (95% CI 0.8 – 6.6) in children with one episode of apnoea (at admission) versus 6.5 (95% CI 3.3 – 12.9) in children with recurrent episodes of apnoea. Conclusions Age below 2 months is the strongest independent risk factor for RSV associated apnoea. Apnoea at admission increases the risk for recurrent apnoea. The risk for mechanical ventilation significantly increases in children who suffer from recurrent apnoea. Received: 12 May 1997 / Accepted in revised form: 22 August 1997     

不同参数激光诱导脉络膜视网膜静脉吻合

目的　探讨不同激光参数、不同击射部位对脉络膜 视网膜静脉吻合形成的影响。方法　在视网膜分支静脉阻塞模型上 ,以不同参数在不同部位诱导吻合支的形成 ,以荧光素眼底血管造影、连续组织切片观察吻合支的建立及其周围组织反应情况。结果　功率 90 0、12 0 0、15 0 0、180 0mW诱导吻合支的成功率为 0、2 0 .83%、4 5 .83%、6 2 .5 0 % (P=0 .0 0 1) ;直径 5 0、10 0 μm诱导吻合支的成功率分别为 4 3.75 %、2 0 .83% (P =0 .0 16 ) ;击射部位距视盘边缘 2DD与 3DD对吻合支形成的影响无统计学意义 (P =0 .732 ) ,2DD与4DD间 (P =0 .0 2 8) ,3DD与 4DD间 (P =0 .0 2 3)差异均有显著性 ;12 0 0、15 0 0mW诱导的吻合支周围组织损伤较轻 ,180 0mW诱导的吻合支周围组织损伤较重。结论　功率、光斑直径是影响脉络膜 视网膜静脉吻合形成的 2个主要因素 ,其中功率起决定性作用 ;5 32nm激光诱导吻合支形成的最适功率和直径为 12 0 0～ 15 0 0mW、5 0 μm ;击射部位以距视盘 3DD处最佳     

渗出型老年性黄斑变性视网膜脉络膜血管吻合与视网膜色素上皮脱离的关系分析

目的 探讨老年性黄斑变性（AMD）视网膜脉络膜血管吻合（RCA）与视网膜色素上皮脱离（PED）的关系。 方法 回顾分析2000年10月～2003年12月诊治的渗出型AMD患者70例75只眼的光相干断层扫描（OCT）和眼底血管造影检查资料，观察有无RCA形成以及与PED 发生的关系。 结果 75只渗出型AMD患眼中，34只眼有RCA形成，占45.3% ；41只眼未见RCA ，占54.7%。有RCA形成同时存在PED者30只，占88.2%；不伴有PED者4只眼，占11.8%。无RCA 形成但存在PED者33只眼，占80.5%；不伴有PED者8只眼，占19.5%。有无RCA形成的患眼PED的发生率比较，差异无显著性的意义（χ2=0.83，P=0.5290）。无RCA形成的33只PED患眼中，发生PED裂孔者17只眼，占51.5%；有RCA形成的30只PED患眼中，发生PED裂孔者26只眼，占8 6.7%，二者比较，差异有显著性的意义（χ2=8.9612，P=0.0030）。 结论 RCA形成在渗出 型AMD患眼中并不少见；RCA多与PED并存，但两者之间无直接的因果关系；PED裂孔发生与RCA形成密切相关。 （中华眼底病杂志，2004，20：295-298）     

长期机械通气的老年患者医院内肺部感染的调查

目的调查和分析长期应用机械通气的老年患者医院内常见的肺部感染。方法对2002年1月~2005年6月住院期间中长期应用机械通气的69例患者进行回顾性分析;对其中普通肺炎的相关危险因素进行Logistic回归分析。结果69例患者中发生普通肺炎53例,肺结核7例,结核性胸膜炎1例,非结核分枝杆菌3例,卡氏肺囊虫8例;引发普通肺炎的相关危险因素是应用通气机的时间和误吸。结论缩短用通气机时间和防止误吸是预防普通细菌性肺炎的重要措施;对长期机械通气的老年患者,还要警惕结核分枝杆菌、非结核分枝杆菌以及卡氏肺囊虫引起的肺部感染。     

胆管空肠吻合术后营养支持研究

目的从临床角度分析胆管空肠吻合术后患者采用肠内营养与肠外营养对患者恢复的差别,评价肠内营养的作用。方法在行胆管空肠吻合术后的患者中,通过72例肠内营养组和67例肠外营养组之间的术后营养状态、免疫功能、并发症发生率、平均住院日、平均费用等的比较分析,比较两组间的差异。结果肠内营养组与肠外营养组术后营养状态、免疫功能无显著差异(P>0.05),并发症发生率、平均住院日、平均费用肠内营养组均明显少于肠外组(P<0.01)。结论早期肠内营养支持应是胆管空肠吻合术后的首选营养支持方案。     

机械通气下极低出生体重儿颅内出血相关因素分析

目的:探讨机械通气下极低出生体重儿(VLBW I)发生颅内出血的相关因素。方法:以NICU收治的机械通气治疗的VLBW I为研究对象,分为颅内出血组和无出血组进行对比分析。结果:颅内出血发生率为47.2%,两组VLBW I孕周越小,上机时间越早,持续时间越长者,越易发生颅内出血。而两组患儿出生体重、1分钟及5分钟Apgar评分均无显著差别(P>0.05);两组的最高FIO2、PIP、PEEP均无显著差别(P>0.05);两组患儿上机前后血气分析PCO2最高及最低值均无显著差别(P>0.05)。结论:在VLBW I需机械通气治疗时,除严格掌握机械通气的指征外,应尽早使用外源性肺表面活性物质,以延迟开始上机时间,缩短用机持续时间,并采取肺保护性通气策略,可减少机械通气下的VLBW I发生颅内出血。     

机械通气在新生儿麻醉中的应用

目的:评价机械通气在新生儿麻醉应用中的安全性和有效性。方法:47例新生儿手术,在全身麻醉气管插管后,行机械定压模式呼吸通气30 m in,监测通气前后动脉血气值、血氧饱和度(SpO2)、体温、呼气末CO2浓度(PetCO2)、气道压(Paw)、呼吸频率(f)、心电等参数。结果:新生儿手术全身麻醉控制呼吸,根据PetCO2适当调节呼吸参数,采用定压呼吸模式,能够维持动脉血氧分压(PaO2)、动脉血CO2分压(PaCO2)于正常范围。结论:机械通气能安全有效地应用于新生儿手术。     

胰腺移植中血管吻合重建的实验研究

目的:研究猪胰腺移植术中不同的血管吻合重建对术后移植胰功能恢复的影响。方法:采用健康小型猪18头体重30~50Kg,雌雄各半,随机分成A、B两组,均作带十二指肠袢的同种异体节段性胰腺移植。A组采用传统血管重建术;B组采用边灌注边吻合、先静脉后动脉的血管重建术。测定各组术后不同天数的胰液淀粉酶小时分泌量平均值、血清C-肽水平,了解移植胰的功能状况。结果:A组术后第5天始血清C-肽、AM分泌量低于B组,两组差异有统计学意义(P<0.05)。结论:胰腺移植术中采用改进后的血管吻合重建术可明显改善术后移植胰的功能。