From the Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan.
Anesth Analg. 2013 May;116(5):1006-1017. doi: 10.1213/ANE.0b013e31828a75bd. Epub 2013 Mar 14.
In managing patients with unstable hemodynamics, monitoring cardiac output (CO) can provide critical diagnostic data. However, conventional CO measurements are invasive, intermittent, and/or inaccurate. The purpose of this study was to validate our newly developed CO monitoring system.
This system automatically determines peak velocity of the ascending aortic flow using continuous-wave Doppler transthoracic echocardiography and estimates cardiac ejection time and aortic cross-sectional area using the pulse contour of the radial arterial pressure. These parameters are continuously processed to estimate CO (CO(est)). In 10 anesthetized closed-chest dogs instrumented with an aortic flowprobe to measure reference CO (CO(ref)), hemodynamic conditions were varied over wide ranges by infusing cardiovascular drugs or by random atrial pacing. Under each condition, CO(ref) and CO(est) were determined. Absolute changes of CO(ref) (ΔCOref) and CO(est) (ΔCO(est)), and relative changes of CO(ref) (%ΔCO(ref)) and CO(est) (%ΔCO(est)) from the corresponding baseline values were determined in each animal. We calibrated CO(est) against CO(ref) to obtain proportionally scaled CO(est) (CO(est)(N)).
A total of 1335 datasets of CO(ref) and CO(est) were obtained, in which CO(ref) ranged from 0.17 to 5.34 L/min. Bland-Altman analysis between CO(ref) and CO(est) indicated that the limits of agreement (the bias ± 1.96 × SD of the difference) and the percentage error (1.96 × [SD of the difference]/[mean CO] × 100) were from -1.01 to 1.13 L/min (95% confidence interval, -1.76 to 1.88 L/min) and 43%, respectively. The agreement between CO(ref) and CO(est)(N) was improved, with limits of agreement from -0.53 to 0.49 L/min (95% confidence interval, -0.62 to 0.59 L/min) and the percentage error of 20%. Polar plot analysis between ΔCO(ref) and ΔCO(est) indicated that mean ± 1.96 × SD of polar angle was -2° ± 22°. Four quadrant plot analysis indicated that %ΔCO(est) correlated tightly with %ΔCO(ref) (R(2) = 0.93). The %ΔCO(est) and %ΔCO(ref) changed in the same direction in 95% of the datasets. Reliability of this system was well preserved under conditions of random atrial pacing and also in a continuous manner.
Over a wide range of hemodynamic conditions, irrespective of cardiac beat irregularity, this system may allow minimally invasive monitoring of CO with a good trending ability. The present results warrant further research and development of this system for future clinical application.
在处理血流动力学不稳定的患者时，监测心输出量（CO）可以提供关键的诊断数据。然而，传统的 CO 测量方法具有侵入性、间歇性和/或不准确性。本研究的目的是验证我们新开发的 CO 监测系统。
该系统使用连续波多普勒经胸超声心动图自动确定升主动脉血流的峰值速度，并使用桡动脉压力的脉搏轮廓来估计心脏射血时间和主动脉横截面积。这些参数被连续处理以估计 CO（CO（est））。在 10 只麻醉并带有主动脉流量探头的闭胸犬中，测量参考 CO（CO（ref）），通过输注心血管药物或随机心房起搏来改变广泛的血流动力学条件。在每种情况下，确定 CO（ref）和 CO（est）。在每个动物中，确定 CO（ref）（ΔCOref）和 CO（est）（ΔCO（est））的绝对变化，以及 CO（ref）（%ΔCO（ref））和 CO（est）（%ΔCO（est））的相对变化与相应的基线值。我们将 CO（est）与 CO（ref）进行校准以获得按比例缩放的 CO（est）（CO（est）（N））。
共获得了 1335 组 CO（ref）和 CO（est）数据，其中 CO（ref）范围为 0.17 至 5.34 L/min。CO（ref）和 CO（est）之间的 Bland-Altman 分析表明，一致性界限（差异的偏置±1.96×SD）和百分比误差（1.96×[差异的 SD]/[平均 CO]×100）分别为-1.01 至 1.13 L/min（95%置信区间，-1.76 至 1.88 L/min）和 43%。CO（ref）和 CO（est）（N）之间的一致性得到改善，一致性界限为-0.53 至 0.49 L/min（95%置信区间，-0.62 至 0.59 L/min），百分比误差为 20%。ΔCO（ref）和ΔCO（est）之间的极坐标图分析表明，极角的平均±1.96×SD 为-2°±22°。四象限图分析表明，%ΔCO（est）与%ΔCO（ref）紧密相关（R（2）=0.93）。在 95%的数据集，%ΔCO（est）和%ΔCO（ref）的变化方向相同。在随机心房起搏和连续的条件下，该系统的可靠性都得到了很好的保持。
在广泛的血流动力学条件下，无论心脏跳动不规则如何，该系统都可以实现对 CO 的微创监测，并具有良好的趋势能力。目前的结果证明了该系统进一步研究和开发用于未来临床应用的必要性。
