Children's Hospital Los Angeles, 4650 Sunset Blvd, MS# 31, Los Angeles, CA 90027, USA.
Arch Dis Child Fetal Neonatal Ed. 2012 Sep;97(5):F340-3. doi: 10.1136/fetalneonatal-2011-301090.
Electrical velocimetry (EV) is a non-invasive method of continuous left cardiac output monitoring based on measurement of thoracic electrical bioimpedance. The objective was to validate EV by investigating the agreement in cardiac output measurements performed by EV and echocardiography.
In this prospective observational study, left ventricular output (LVO) was simultaneously measured by EV (LVO(ev)) using Aesculon and by echocardiography (LVO(echo)) in healthy term neonates during the first 2 postnatal days. To determine the agreement between the two methods, we calculated the bias (mean difference) and precision (1.96×SD of the difference). As LVO(echo) has its own limitations, the authors also calculated the 'true precision' of EV adjusted for echocardiography as the reference method.
The authors performed 115 paired measurements in 20 neonates. LVO(ev) and LVO(echo) were similar (534±105 vs 538±105 ml/min, p=0.7). The bias and precision of EV were -4 and 234 ml/min, respectively. The authors found the true precision of EV to be similar to the precision of echocardiography (31.6% vs 30%, respectively). There was no difference in bias and precision between the measurements obtained in patients with or without a haemodynamically significant patent ductus arteriosus.
EV is as accurate in measuring LVO as echocardiography and the variation in the agreement between EV and echocardiography among the individual subjects reflects the limitations of both techniques.
基于胸部电阻抗测量的电流速法（EV）是一种非侵入性的连续左心输出量监测方法。本研究旨在通过比较 EV 和超声心动图测量心输出量的一致性来验证 EV。
在这项前瞻性观察性研究中，在出生后第 1 至第 2 天，使用 Aesculon 对健康足月新生儿同时进行 EV（LVO（ev））和超声心动图（LVO（echo））测量左心室输出量（LVO）。为了确定两种方法的一致性，我们计算了偏倚（均值差）和精密度（差值的 1.96×SD）。由于 LVO（echo）本身存在局限性，作者还计算了 EV 的“真实精密度”，将超声心动图作为参考方法进行了校正。
作者在 20 名新生儿中进行了 115 次配对测量。LVO（ev）和 LVO（echo）相似（534±105 vs 538±105 ml/min，p=0.7）。EV 的偏倚和精密度分别为-4 和 234 ml/min。作者发现 EV 的真实精密度与超声心动图的精密度相似（分别为 31.6%和 30%）。在有或没有血流动力学显著动脉导管未闭的患者中，测量的偏倚和精密度均无差异。
EV 测量 LVO 的准确性与超声心动图相当，个体间 EV 和超声心动图之间一致性的差异反映了两种技术的局限性。
