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Continuous cardiac output measurements using a newly developed pulmonary artery Doppler catheter combined with intravascular ultrasound tehnique.

使用新开发的肺动脉多普勒导管结合血管内超声技术进行连续心输出量测量。

基本信息

批准号：
09557126
负责人：
AKAMATSU Shigeru
金额：
$ 5.12万
依托单位：
Gifu University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

Cardiac output is one of the most crucial parameters measured in critically ill patients. The current procedure used to measure cardiac output has been as bolus thermodilution, a technique based on the law of conservation of energy. Although the bolus thermodilution technique is widely accepted as the clinical standard, the technique provides only intermittent information, and the procedure is time-consuming. In critically ill patients, as hemodynamic status may change rapidly, continuous cardiac output monitoring would provide timely information to permit rapid institution and adjustment of therapy. Various technologies for continuous monitoring of cardiac output have been examined by many researchers and clinicians for overa decade.Measurement of cardiac output using continuous thermodilution technique is technology clinically available. Continuous-thermodilution using pulmonary artery catheter is an injectless system, which incorporates a thermal filament to provide intermittent per … More iods of heat, which is sensed by a distal thermistor. This system provides the average cardiac output over several minutes with a 30-second update. Continuous thermodilution provides acceptable accuracy for clinical situalion, however, it does not provide real-time values. The value indicates the average cardiac output over several minutes, it does not indicate real-time value. Doppler ultrasound techniques have been used for measurement of continuous velocity and, thus, of cardiac output. These techniques are superior in real time basis, however, they suffer from inaccuracy because of their inherent dependency on the angle between the ultrasound beam and the now direction(Doppler angle). Doppler angle would constitute the errors in velocity measurements and in cardiac output measurements. Cardiac output measured by these techniques would not be reliable clinically. So, We have devdoped a new pulmonary artery Doppler catheter, which overcomes this angle dependency, to accurately monitor cardiac output continuously.Our pulmonary artery Doppler catheter is a modified PA catheter. The catheter has a special lumen for measurement of cross sectional area of pulmonary artery using intravascular ultrasound technique. The catheter was also modified by mounting 2 ultrasound transducer crystals on its distal tip. We combined Doppler ultrasound technique with pulmonary artery catheter, and also combined intravascular ultrasound technique with Doppler ultrasound technique. Thus, cardiac output is able to measure using flow velocity and cross-sectional area of pulmonary artery. A pair of ultrasonic transducers positioned at a fixed angle was mounted on the distal section of pulmonary artery catheter to be positioned in the main pulmonary artery. The Doppler shifts(Δf1, Δf2)were detected by two transducers sampling at closely spaced two points in the main pulmonary artery. The values of Δf1 and Δf2 were used to compute two velocity measurements, and true flow velocity of pulmonary artery was calculated using following equation : V=(V1)^2+(V2)^2)^<1/2>, where V=true velocity, V1 and V2 =velocity detected by the transducer 1 and 2. The velocities were calculated using newly developed phase differential techniques. Cross-sectional area of pulmonary artery was revealed and measured using intravascular ultrasound technique through the special lumen of our pulmonary artery catheter. For the measurements of cross-sectional area of pulmonary artery, intravascular ultrasound technique is more accurate than transthoracic or transecophageal echocardiography. Regarding to continuous cardiac output measurements, after IRB approval, we evaluated the availability of our newly developed pulmonary artery Doppler catheter in animal experiments. We found that cardiac output measured by our newly developed pulmonary artery Doppler catheter gave us accurate value, which could applicable for critically ill patients.Using a newly developed pulmonary artery Doppler catheter, we are able to continuously measure cardiac output. This technique for continuously measuring cardiac output in real time is superior to other modified thermodilution techniques. Less

心输出量是危重病人最重要的指标之一。目前用于测量心排血量的方法是基于能量守恒定律的热稀释法。虽然大剂量热稀释技术被广泛接受为临床标准，但该技术只能提供间歇性的信息，而且过程耗时。对于危重患者，由于血流动力学状态可能发生快速变化，持续的心输出量监测将提供及时的信息，以便快速制定和调整治疗方案。十多年来，许多研究人员和临床医生对心输出量连续监测的各种技术进行了研究。使用连续热稀释技术测量心输出量是临床上可用的技术。使用肺动脉导管的连续热稀释是一种无注射系统，它包含一个热丝来提供间歇性的每…更多的热量，这是由一个远端热敏电阻感应。该系统提供几分钟内的平均心输出量，每30秒更新一次。连续热稀释为临床情况提供了可接受的准确性，然而，它不能提供实时值。该数值表示几分钟内的平均心输出量，不代表实时值。多普勒超声技术已用于测量连续流速，从而测量心输出量。这些技术在实时基础上具有优势，但由于其固有的依赖于超声束与当前方向之间的角度（多普勒角），因此存在不准确性的问题。多普勒角会在速度测量和心输出量测量中造成误差。这些技术测量的心输出量在临床上并不可靠。因此，我们开发了一种新的肺动脉多普勒导管，克服了这种角度依赖，可以连续准确地监测心输出量。我们的肺动脉多普勒导管是一种改良的PA导管。导管有一个特殊的管腔，用于血管内超声技术测量肺动脉的横截面积。导管还通过在其远端末端安装2个超声换能器晶体进行了改进。我们将多普勒超声技术与肺动脉导管相结合，并将血管内超声技术与多普勒超声技术相结合。因此，心输出量可以通过流速和肺动脉截面积来测量。将一对超声换能器固定角度安装在肺动脉导管远端，定位于肺动脉主干。多普勒频移（Δf1， Δf2）由两个换能器在肺动脉主动脉紧密间隔的两点采样检测。利用Δf1和Δf2的值计算两次流速测量值，肺动脉真流速的计算公式为：V=(V1)^2+(V2)^2)^<1/2>，其中V=真流速，V1和V2 =传感器1和2检测到的流速。速度是用新发展的相位差技术计算的。利用血管内超声技术，通过肺动脉导管的特殊管腔，显示和测量肺动脉的横截面积。对于肺动脉横截面积的测量，血管内超声技术比经胸或经食管超声心动图更准确。关于心输出量的持续测量，在IRB批准后，我们评估了我们新开发的肺动脉多普勒导管在动物实验中的可用性。我们发现新研制的肺动脉多普勒导管所测量的心输出量值准确，适用于危重病人。使用新开发的肺动脉多普勒导管，我们能够连续测量心输出量。这种实时连续测量心输出量的技术优于其他改良的热稀释技术。少