Influence of different electrode belt positions on electrical impedance tomography imaging of regional ventilation: a prospective observational study.
Influence of different electrode belt positions on electrical impedance tomography imaging of regional ventilation: a prospective observational study.
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DOI：
10.1186/s13054-015-1161-9
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发表时间：
2016-01-08
期刊：
影响因子：
--
通讯作者：
Heinze H
中科院分区：
文献类型：
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作者：
Karsten J;Stueber T;Voigt N;Teschner E;Heinze H
电阻抗断层扫描（EIT）是一种无创性床边工具，通过监测潮气通气和肺通气，可以制定个性化的呼吸机策略。EIT可以在不同的颅尾胸椎水平进行，但关于最佳带位置的数据缺失。这项前瞻性观察研究的主要目标是评估不同电极层对潮汐阻抗变化与全球体积变化的影响，以便提出EIT测量的适当带位置。对15例机械通气重症监护患者在不同胸层（L1-L7）使用电极带进行EIT测量。记录所有呼吸和血流动力学参数。在EIT检查开始时进行一次血气分析。离线潮气阻抗变化/潮气量（TV/VT）的比率进行了计算，并确定了由于自动和用户定义的EIT图像的色标调整的阻抗分布的特定模式。TV/VT比值在L1最高。它在尾部方向减少。在L5，TV/VT比值显著降低。我们可以识别与通气相关的阻抗变化的干扰模式，由于自动调整的色标，在定期显示的EIT图像中并不明显。EIT测量的临床可用性和可行性取决于适当的带位置、适当的阻抗可视化、正确的分析和数据解释。当EIT用于估计全局参数（如VT或呼气末肺容积的变化）时，最佳电极平面位于第4和第5肋间空间之间。特定的颜色编码偶尔会抑制用户相关信息，并且需要手动重新缩放图像以可视化此信息。
Electrical impedance tomography (EIT) is a non-invasive bedside tool which allows an individualized ventilator strategy by monitoring tidal ventilation and lung aeration. EIT can be performed at different cranio-caudal thoracic levels, but data are missing about the optimal belt position. The main goal of this prospective observational study was to evaluate the impact of different electrode layers on tidal impedance variation in relation to global volume changes in order to propose a proper belt position for EIT measurements. EIT measurements were performed in 15 mechanically ventilated intensive care patients with the electrode belt at different thoracic layers (L1-L7). All respiratory and hemodynamic parameters were recorded. Blood gas analyses were obtained once at the beginning of EIT examination. Off-line tidal impedance variation/tidal volume (TV/VT) ratio was calculated, and specific patterns of impedance distribution due to automatic and user-defined adjustment of the colour scale for EIT images were identified. TV/VT ratio is the highest at L1. It decreases in caudal direction. At L5, the decrease of TV/VT ratio is significant. We could identify patterns of diaphragmatic interference with ventilation-related impedance changes, which owing to the automatically adjusted colour scales are not obvious in the regularly displayed EIT images. The clinical usability and plausibility of EIT measurements depend on proper belt position, proper impedance visualisation, correct analysis and data interpretation. When EIT is used to estimate global parameters like VT or changes in end-expiratory lung volume, the best electrode plane is between the 4th and 5th intercostal space. The specific colour coding occasionally suppresses user-relevant information, and manual rescaling of images is necessary to visualise this information.