Measurement uncertainty in pulmonary vascular input impedance and characteristic impedance estimated from pulsed-wave Doppler ultrasound and pressure: clinical studies on 57 pediatric patients

被引:6
作者
Tian, Lian [1 ]
Hunter, Kendall S. [2 ,3 ]
Kirby, K. Scott [2 ]
Ivy, D. Dunbar [2 ]
Shandas, Robin [1 ,2 ,3 ]
机构
[1] Univ Colorado, Dept Mech Engn, Boulder, CO 80309 USA
[2] Univ Colorado Denver, Childrens Hosp, Dept Pediat Cardiol, Aurora, CO 80045 USA
[3] Univ Colorado Denver, Dept Bioengn, Aurora, CO 80045 USA
基金
美国国家卫生研究院;
关键词
uncertainty; systematic error; random error; input impedance; characteristic impedance; pediatric patient; HYPERTENSION; RESISTANCE; VELOCITY; FLOW;
D O I
10.1088/0967-3334/31/6/001
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Pulmonary vascular input impedance better characterizes right ventricular (RV) afterload and disease outcomes in pulmonary hypertension compared to the standard clinical diagnostic, pulmonary vascular resistance (PVR). Early efforts to measure impedance were not routine, involving open-chest measurement. Recently, the use of pulsed-wave (PW) Doppler-measured velocity to non-invasively estimate instantaneous flow has made impedance measurement more practical. One critical concern remains with clinical use: the measurement uncertainty, especially since previous studies only incorporated random error. This study utilized data from a large pediatric patient population to comprehensively examine the systematic and random error contributions to the total impedance uncertainty and determined the least error prone methodology to compute impedance from among four different methods. We found that the systematic error contributes greatly to the total uncertainty and that one of the four methods had significantly smaller propagated uncertainty; however, even when this best method is used, the uncertainty can be large for input impedance at high harmonics and for the characteristic impedance modulus. Finally, we found that uncertainty in impedance between normotensive and hypertensive patient groups displays no significant difference. It is concluded that clinical impedance measurement would be most improved by advancements in instrumentation, and the best computation method is proposed for future clinical use of the input impedance.
引用
收藏
页码:729 / 748
页数:20
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