Department of Anesthesiology, Center of Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Author to whom any correspondence should be addressed.
Physiol Meas. 2018 Feb 28;39(2):024002. doi: 10.1088/1361-6579/aaa924.
Electrical impedance tomography (EIT) is a non-invasive and radiation-free bedside monitoring technology, primarily used to monitor lung function. First experimental data shows that the descending aorta can be detected at different thoracic heights and might allow the assessment of central hemodynamics, i.e. stroke volume and pulse transit time.
First, the feasibility of localizing small non-conductive objects within a saline phantom model was evaluated. Second, this result was utilized for the detection of the aorta by EIT in ten anesthetized pigs with comparison to thoracic computer tomography (CT). Two EIT belts were placed at different thoracic positions and a bolus of hypertonic saline (10 ml, 20%) was administered into the ascending aorta while EIT data were recorded. EIT images were reconstructed using the GREIT model, based on the individual's thoracic contours. The resulting EIT images were analyzed pixel by pixel to identify the aortic pixel, in which the bolus caused the highest transient impedance peak in time.
In the phantom, small objects could be located at each position with a maximal deviation of 0.71 cm. In vivo, no significant differences between the aorta position measured by EIT and the anatomical aorta location were obtained for both measurement planes if the search was restricted to the dorsal thoracic region of interest (ROIs).
It is possible to detect the descending aorta at different thoracic levels by EIT using an intra-aortic bolus of hypertonic saline. No significant differences in the position of the descending aorta on EIT images compared to CT images were obtained for both EIT belts.
电阻抗断层成像（EIT）是一种非侵入性、无辐射的床边监测技术，主要用于监测肺功能。初步实验数据表明，降主动脉可在不同的胸腔高度被检测到，并且可能允许评估中心血流动力学，即每搏量和脉搏传导时间。
首先，评估了在盐水体模模型中定位小的非导电物体的可行性。其次，利用 EIT 在 10 头麻醉猪中检测降主动脉，将 EIT 与胸部计算机断层扫描（CT）进行比较。将两个 EIT 带放置在不同的胸腔位置，在上腔静脉内给予高渗盐水（10ml，20%），同时记录 EIT 数据。使用基于个体胸部轮廓的 GREIT 模型对 EIT 图像进行重建。对重建的 EIT 图像进行逐像素分析，以识别在时间上引起最高瞬时阻抗峰值的主动脉像素。
在体模中，小物体可以在每个位置定位，最大偏差为 0.71cm。在体内，如果仅在背部感兴趣区（ROI）内进行搜索，则 EIT 测量的主动脉位置与解剖主动脉位置之间在两个测量平面上没有显著差异。
使用主动脉内高渗盐水 bolus，EIT 可以在不同的胸腔水平检测降主动脉。对于两个 EIT 带，EIT 图像上降主动脉的位置与 CT 图像相比没有显著差异。
