Hull E T, Irie T, Heemstra H, Wildevuur R H
Resuscitation. 1978;6(2):115-24. doi: 10.1016/0300-9572(78)90018-7.
The applicability of transthoracic impedance measurements for estimating thoracic fluid volume and tidal volume is limited by large variations associated with electrode movement, repeated application of electrodes and inter-individual differences. These sources of variation were studied with a four-electrode impedance-measuring device in anaesthetized dogs. Electrode movement artifacts affecting both the resting expiratory value of impedance (Zo) and the respiratory change of impedance (deltaZ/VT) could be largely eliminated by rigidly fixing the distances between the current-supplying and the potential-sensing electrodes. The reproducibility of Zo and deltaZ/VT was found to be affected adversely by local conductivity changes in the skin induced by repeated removal of the glued electrodes. Inter-individual variations in Zo and deltaZ/VT correlated with the thickness of thoracic subcutaneous fat (r = 0.86) and thoracic circumference (r = -0.95) respectively. Correction for these sources of inter-individual variation allowed the standard deviations of Zo and deltaZ/VT to be reduced from 18% to 7% and from 51% to 17% of their respective mean values.
经胸阻抗测量用于估计胸腔液体量和潮气量的适用性受到与电极移动、电极重复应用以及个体差异相关的巨大变异性的限制。使用四电极阻抗测量装置在麻醉犬中研究了这些变异来源。通过严格固定供电电极和电位感应电极之间的距离，可在很大程度上消除影响阻抗静息呼气值（Zo）和阻抗呼吸变化（deltaZ/VT）的电极移动伪影。发现Zo和deltaZ/VT的可重复性受到反复去除粘贴电极引起的皮肤局部电导率变化的不利影响。Zo和deltaZ/VT的个体间变异分别与胸部皮下脂肪厚度（r = 0.86）和胸围（r = -0.95）相关。对这些个体间变异来源进行校正后，Zo和deltaZ/VT的标准差分别从其各自平均值的18%降至7%，从51%降至17%。
