Khambete N D, Brown B H, Smallwood R H
Department of Medical Physics and Clinical Engineering, The University of Sheffield, Royal Hallamshire Hospital, UK.
Physiol Meas. 2000 Feb;21(1):79-88. doi: 10.1088/0967-3334/21/1/310.
In this paper, we have proposed a technique for reducing movement artefacts in impedance pneumography by placing six electrodes at appropriate locations and suitably combining the measurements obtained. The strategy for electrode placement was based on the observation that the electrodes appeared to slide over the rib cage along with the skin, during movement. A volume conductor model of the thoracic cavity was developed and movement artefacts were simulated by shifting the electrodes to a different location on the surface. The impedance changes due to movement in one of the measurements of a 'symmetrical pair' were 180 degrees out of phase with respect to those observed in the other measurement of that pair. However, the impedance changes due to breathing were in phase in both these measurements. Thus, it was possible to reduce movement artefacts by taking a mean of these measurements without affecting the breathing related changes. The six electrodes could be configured into two such symmetrical pairs. The same observation was made in experimental data recorded from human subjects. This indicated that movement artefacts were caused by sliding of electrodes along with the skin and could be reduced by using the six-electrode configuration.
在本文中，我们提出了一种通过在适当位置放置六个电极并对所获得的测量值进行适当组合来减少阻抗式呼吸描记术中运动伪影的技术。电极放置策略基于这样的观察结果：在运动过程中，电极似乎会随着皮肤在胸腔上滑动。我们建立了胸腔的容积导体模型，并通过将电极移动到表面上的不同位置来模拟运动伪影。在“对称对”的其中一次测量中，由于运动引起的阻抗变化与该对另一次测量中观察到的阻抗变化相差180度相位。然而，在这两次测量中，由于呼吸引起的阻抗变化是同相的。因此，通过对这些测量值求平均值来减少运动伪影是可行的，同时不会影响与呼吸相关的变化。这六个电极可以配置成两个这样的对称对。在从人体受试者记录的实验数据中也得到了相同的观察结果。这表明运动伪影是由电极随皮肤滑动引起的，并且可以通过使用六电极配置来减少。
