电阻抗法监护小猪腹膜后出血的实验研究

目的 通过应用电阻抗成像系统(EIT)对腹膜后出血动物模型进行监护实验,验证EIT的成像效果且为EIT的临床应用提供必要的理论和实验依据.方法 首先应用细针在B超引导下体外穿刺全身肝素化后的小猪肾脏,制成腹膜后出血动物模型,然后用EIT对穿刺后的小猪进行监护成像.结果 5只小猪被穿刺后均存活3h以上,且均发生了肾脏出血,动物模型成功率为100%,出血量在100～180ml之间.EIT监护系统成像清楚,出血区与未出血区图像比较反差大,图像对比度明显,并随穿刺后监护时间的延长,图像灰度值明显变小,相应部位阻抗值变小.经解剖及CT验证,后腹膜完整.血液局限于腹膜后间隙内.结论 EIT监护系统成像清晰,使用EIT监护腹膜后出血是可行的.     

家兔腹部内出血模型电阻抗断层成像初步研究

目的研究模拟动物腹部内出血与电阻抗断层成像之间的关系,以便为人体监护提供必要的理论和现实依据.方法实验环境选择在屏蔽室,采用家兔作为实验对象,采用银丝电极皮下缝埋,固定姿势分别向其腹部注入10ml、20ml、30ml、40ml、50ml血液,观察注血量与所呈图像灰度的变化.结果图像的灰度值随注血量的增加而减小.结论图像的灰度值与注血量高度相关.     

电阻抗成像监护家兔腹内出血的实验研究

目的 为腹腔内出血监护研究建立一种家兔动物模型。通过对家兔腹腔内出血动物模型进行的监护实验，检验一种新研制的腹部出血电阻抗成像监护系统（EIT腹腔内出血监护系统）的成像效果。方法 ①应用专用撞击器对家兔肝外部进行撞击，制作家兔腹内出血动物模型。②用EIT对撞击后的家兔进行监护成像，检验实际成像效果。结果 ①15只家兔被撞击后，均发生了肝出血，出血率为100％，出血量在35—50ml之间，15只家兔均在被撞击后存活3h以上。②EIT腹腔内出血监护系统成像清楚，出血与未出血图像比较反差很大，图像对比度明显，并随出血量的增多图像最小灰度值明显变小。结论 ①家兔腹腔出血动物模型的建立是成功的。②EIT腹腔内出血监护系统成像结果较为清晰，对比明显。     

异位妊娠的辅助检查评价——附110例临床分析

本文对我院1989年1月至1989年12月110例经手术及病理证实为异位妊娠的辅助检查进行分析，比较B超、血hcG、尿妊娠试验、诊刮、后穹窿穿刺、腹腔穿刺及血常规才诊断异位妊娠的价值。发现在辅助检查中，B超阳性率最高，达95%。血hcG阳性价值很大，假阳性罕见，但血hcG不能区别宫内孕与宫外孕。后穹窿穿刺或腹腔穿刺检查是宫外孕剖腹探查指征。尿妊娠试验一般作为疑有宫外孕或鉴别诊断时筛选检测项目。文中还就诊刮和Hb检查对宫外孕的诊断进行了评价。     

人体区域电阻抗测量的研究现状

生物电阻抗技术作为无创性人体信息检测方法，已在临床检查和监护中得到一定的应用，但为了获得良好的空间定位信息，需要提高空间分辨率，因此人体区域阻抗的测量一直是人们关心的问题。本文扼要介绍了近年人体区域阻抗测量的研究现状，涉及了电阻抗成像技术和采用保护电极法、补偿法和外加磁场法进行区域电阻抗测量的技术。     

人体区域电阻抗测量的研究现状

生物电阻抗技术作为无创性人体信息检测方法，已在临床检查和监护中得到一定的应用，但为了获得良好的空间定位信息，需要提高空间分辨率，因此人体区域阻抗的测量一直是人们关心的问题。本文扼要介绍了近年人体区域阻抗测量的研究现状，涉及了电阻抗成像技术和采用保护电极法、补偿法和外加磁场法进行区域电阻抗测量的技术。     

乳腺电阻抗投影成像算法及实现

研究并验证电阻抗乳腺投影成像算法。该算法将乳腺等效为均匀,利用均匀介质电流场扰动原理,将场域内电阻抗异常区域投影到边界的电流分布,采用物理模型实验进行验证。该算法能识别2mm的电阻抗扰动目标,识别的目标深度可达25mm。电阻抗乳腺投影成像算法可以用于乳腺内异常电阻区的探查。     

基于斜位电流注入的磁共振电阻抗成像谐函数Bz重建算法及实验研究

针对斜位电流注入的磁共振电阻抗成像,提出基于斜位电流注入的谐函数Bz电导率重建算法,并建立相应的二维电导率重建方案。在构建磁共振电阻抗成像实验系统的基础上,分别进行电导率分布图像的仿真和测量磁通密度的实验。仿真结果表明,所提出的重建算法能够获得电导率分布的图像,并且硬件系统能够获得对成像物体注入电流时的磁共振图像数据,进一步可以得到成像体内的磁通密度。     

多发性肝细胞腺瘤1例

患者,男,42岁。1984年因右上腹部阵发性疼痛伴恶心呕吐,曾去上海多家医院诊治,经B超、CT及肝扫描检查,诊为原发性肝癌。化疗两个疗程,因病人反应严重而中止治疗。两年后病情无明显变化,入本院复诊。查体:发育正常,营养良好,巩膜无黄染,腹部平坦,肝睥未触及,右上愎深压痛。肝功能化验正常,AFP阴性。B超示肝脏多发性占位性病变,考虑肝血管瘤。为明确诊断,于1987年3月行剖腹探查术。术中见肝脏表面呈多发性结节,其大小为0.4cm～3     

CT检查在肝脏外伤中的应用价值

目的探讨CT检查在肝脏外伤诊断中的临床应用价值。方法分析本院近年来20例肝脏创伤的CT影像表现。结果肝实质破裂出血12例,肝包膜下出血10例,腹腔积血16例。结论CT检查因其简便、直观,对肝脏损伤有极高的敏感性、特异性和准确性,能清晰显示肝脏的形态异常、临近器官的侵及情况及腹膜后结构异常,对肝脏外伤及其并发症的诊断和治疗具有重要指导作用。     

Value of semiquantitative cultures of blood drawn through catheter hubs for estimating the risk of catheter tip colonization in cancer patients.

Colonization of central catheter tips has been associated with catheter-related infections. This colonization is defined as the presence of over 15 CFU in a semiquantitative catheter tip culture performed after catheter removal. Using a simple pour-plate technique, we determined the microbial concentrations in samples of blood collected via the hubs of 205 central catheters while they were in position in 179 cancer patients. All catheters were removed within three days of blood collection via the hub and cultured semiquantitatively. We then compared the results for the hub blood cultures and catheter tip cultures. Cultures from 18% of the hub samples and 29% of the tips were positive. When a cutoff limit of 1,000 CFU/ml was used for the blood cultures, the sensitivity was 20% and the specificity was 99% for estimating catheter tip colonization. These values did not seem to be related to the underlying disease, the site of catheter insertion, or the antibiotic treatment administered at catheter removal. We conclude that, if positive, cultures of blood sampled via the catheter hub can be useful in assessing the risk of catheter colonization in cancer patients.     

Extracorporeal therapies: should we use plasma instead of blood?

The evolution of extracorporeal therapies has required the parallel evolution of devices designed to extract the blood from the patient and to move it in the extracorporeal circuit. Blood is a peculiar fluid in which viscosity may be strongly affected by the contingent operational conditions of the extracorporeal circuit. Because hematocrit is an important component of blood viscosity, and viscosity may definitely affect the performance of blood purification devices, major problems arise when high hematocrits are present in the patient. All these problems might be avoided if plasma could be used instead of whole blood. Plasma treatment is already performed in various therapies, but the treated plasma is obtained by separation from whole blood in the extracorporeal environment. In this paper we propose a new approach to perform different plasma treatments. Plasma is extracted directly from the patient thanks to a special catheter or plasma extraction device. Utilizing plasmafiltration technology to create a membrane that is placed on the tip of an intravascular catheter, plasma extraction may become easy to perform. The extracted plasma is then available for any type of treatment before being restituted to the patient via a second lumen in the same catheter.     

Precautions for measuring blood flow during anemia with the microsphere technique

Preliminary data from a study of the effects of anemia on organ blood flow showed large discrepancies between cardiac output measured with the microsphere technique and simultaneous values calculated by the Fick principle. The most likely explanation was that the reference sample drawn according to our standard procedure underestimated the microsphere concentration in arterial blood, resulting in erroneously high blood flow values. In the present experiments we compared our usual reference sample, from a small catheter advanced from a peripheral artery into the brachiocephalic artery (withdrawal rate 1.3 ml/min), with a simultaneous sample from a larger catheter withdrawn at the much higher rate (7.89 ml/min). At hematocrits above 32%, microsphere concentrations from the two catheters were similar, but below 32% the concentration of microspheres in blood from the larger catheter was 30-50% more than from the smaller. The discrepancy was not altered by changing the injection site from left ventricle to left atrium and thus was probably not the result of poor mixing within the heart. It may have been the result of nonhomogeneous distribution of microspheres within larger vessels, perhaps as a consequence of laminar flow and axial streaming of both red blood cells and microspheres during anemia. Whatever the cause, it was possible to eliminate the difference by withdrawing from the smaller catheter at a more rapid rate (2.46 ml/min).     

Remote-controlled device for sampling arterial blood in unrestrained animals

A device is described that allows remote-controlled sampling of arterial blood in unrestrained animals. An artery and a vein are dissected in local anesthesia and connected by a plastic catheter, the sampling catheter. The flow of arterial blood in this artificial shunt can be blocked by kinking the sampling catheter by a remote-controlled device. The blood thus trapped in the sampling catheter, of 0.45 ml volume is analyzed for PO2, PCO2, and pH using electrodes. The technique has been used in ducks and hens but can be applied to other vertebrate classes and to species of smaller body size.     

Catheter-related bloodstream infection caused by Mycobacterium brumae

Mycobacterium brumae is a rapidly growing environmental mycobacterial species identified in 1993; so far, no infections by this organism have been reported. Here we present a catheter-related M. brumae bloodstream infection in a 54-year-old woman with breast cancer. The patient presented with high fever (39.7 degrees C), and >1,000 colonies of M. brumae grew from a quantitative culture of blood drawn through the catheter. A paired peripheral blood culture was negative, however, suggesting circulational control of the infection. The patient was treated empirically with meropenem and vancomycin, and the fever resolved within 24 h. The catheter was removed a week later, and from the tip M. brumae was isolated a second time, suggesting catheter colonization. The organism was identified by colonial morphology, sequence analysis of the 16S rRNA gene, and biochemical tests.     

Acute Shunt Malfunction after Cesarean Section Delivery: A Case Report

Shunt malfunctions that require surgical intervention during pregnancy and the postpartum period are rare. Furthermore, no study has reported on an acute shunt malfunction immediately after cesarean section. Here, we describe the case of a 32-yr-old woman who became drowsy 12 hr after cesarean section delivery of her second child. She had a ventriculoperitoneal shunt placed to treat hydrocephalus associated with meningitis at 26 yr of age. Marked ventriculomegaly was seen on brain computed tomography and her consciousness recovered temporarily after aspirating cerebrospinal fluid from the flushing device. At surgery, the distal catheter tip was plugged by a blood clot. We believe that the blood spilled over during the cesarean section. The clogged catheter end was simply cut off and the remaining catheter was repositioned in the peritoneal cavity. Her consciousness recovered fully.     

Development and evaluation of new devices for use in the central venous catheter system

The central venous catheter (CVC) is considered the most reliable type of temporary blood access, and longer-term blood purification has become possible with its improvement. We report the clinical evaluation of a new CVC, the Tornado catheter, and discuss complications associated with the long-term use of the CVC (L-CVC). We placed Tornado catheters in the internal jugular vein for 1–2 weeks in 10 patients. L-CVC were employed in 14 patients undergoing maintenance hemodialysis (HD). In only 2 of 10 patients with a Tornado catheter, the blood flow was decreased during HD due to clot formation on the arterial side. No patients had other complications. In patients with L-CVC, poor blood flow often occurred. In two patients with cardiac dysfunction, we have been using CVC for more than 12 months. The development of a CVC that will serve as a permanent blood access is expected.     

Evaluation of central venous catheter sepsis by differential quantitative blood culture

The accuracy of differential quantitative blood culture in the diagnosis of central venous catheter sepsis was evaluated in 24 parenterally-fed patients in whom catheter sepsis was suspected. The pour-plate quantitative culture technique was performed immediately before removal of the catheter on blood drawn through the central venous catheter and a peripheral vein. If bacterial colonies in the catheter blood specimen were sevenfold more frequent than identical bacterial colonies in the peripheral blood specimen, the test was considered positive and indicative of catheter sepsis. Catheter-tip culture identified 9 of the 24 patients as positive for catheter sepsis. A positive differential quantitative blood culture result was found for seven of the nine infected catheters. Sensitivity of this test was 77.8%, specificity was 100%, and overall accuracy was 91.7%. It is concluded that differential quantitative blood culture is a reliable method for the exclusion of catheter sepsis.     

Optimization and safety of the intra-aortic balloon pumping balloon catheter

Tokai Medical Products developed an intra-aortic balloon pumping (IABP) balloon catheter with the following unique characteristics: the balloon can be applied to any patient irrespective of their physical size, and is therefore suitable for Japanese patients of small stature; a long soft tip is used, which is designed to avoid damage to blood vessels; the size of the catheter is reduced to 7 Fr, and the catheter can be used as a multifunctional balloon catheter, such as the Yoshioka type, that allows simultaneous percutaneous coronary intervention (PCI). The safety of this catheter has been proven in scientific studies. In this review, we report the development of our IABP balloon catheter and give an outline of its characteristics.     

Randomized study of temporary hemodialysis catheters

Temporary catheters are still essential for acute dialysis access but their performance has not been compared in randomized trials. We conducted a randomized trial of our standard catheter and a newly designed catheter. The primary outcome was maximized blood flow over the entire use of the catheter. Seventy-six patients provided maximum blood flows. The new catheter provided an average blood flow of 349 ml/min and the standard catheter provided flows of 320 ml/mm (p=0.09). Lumen reversal occurred in 56.8% of dialysis sessions with the standard catheter compared to 27.4% with the new catheter (p<0.001). Left-sided internal jugular catheters and catheters inserted in females provided 103 ml/min and 36 ml/min less blood flow, respectively, compared to right sided catheters and catheters placed in males. Approximately 20% of catheters were removed for poor blood flow. Left sided catheters and catheters in females were more likely to need removal for malfunction but catheter design did not influence removal rates.