经气管超声多普勒测定心排血量相关性及准确性的实验研究

Continuous cardiac output determination using transtracheal Doppler:an experimental comparison with thermodilution

通过实验研究评价TTD的准确性,并观察其影响因素。犬11条,体重8～15kg,2.5%硫喷妥钠20mg/kg麻醉后,将Doppler气管导管插入气管内,并与Doppler显示器和微机相连,进行CO测定。同时经股静脉插入光纤肺动脉导管,用温度稀释法测定CO。实验步骤分为:①基础状态;②静注异丙酚2mg/kg;③静注多巴胺100μg/kg;④ 1:1血液稀释。结果:TTD与TD高度相关(r^2=0.88);两法测定CO的Bias为-0.0817L/min。结果表明:① TTD测定CO准确可靠。②影响TTD测定的主要因素有:操作技术;导管位置及固定;主动脉直径的测定及超声束和血流方向的夹角。

The aim of this study was to evaluate the accuracy of transtracheal doppler (TTD) cardiac output monitoring. Eleven mongrel dogs (weight: 8～15kg) were anesthetized with intravenous thiopental 20mg·kg^(-1), and the doppler tube was inserted into trachea and fixed at a proper position where clear signal was received, and the catheter with thermistor was passed into pulmonary artery via femoral vein. CO were measured simultanously by thermodilution (TD) and TTD in the basic state, during 10 mins after intravenous administration of propofol 2mg·kg^(-1), in 30 mins following intravenous dopamine 100μg·kg^(-1) or under condition of isovolumic hemodilution in sequence. The results demonstrated that the CO measured by TTD correlated positively with that by TD (r=0.88, P<0.01), and the mean CO difference between TTD and TD was--0.082±0.24L·min^(-1). It is suggested that TTD may allow of accurate CO monitoring, however its accuracy can be affected by user's skill, doppler tube location and fixing, aortic diameter measurement and the angle between doppler signal and direction of blood flow.