Department of Anaesthesiology, Centre for Anaesthesiology and Intensive Care Medicine, University Medical Centre Hamburg-Eppendorf, Martinistr. 52, Hamburg D-20246, Germany
Department of Pulmonary and Critical Care, Oregon Health and Science University, Portland, OR, USA.
Br J Anaesth. 2017 Jan;118(1):68-76. doi: 10.1093/bja/aew341.
Functional imaging by thoracic electrical impedance tomography (EIT) is a non-invasive approach to continuously assess central stroke volume variation (SVV) for guiding fluid therapy. The early available data were from healthy lungs without injury-related changes in thoracic impedance as a potentially influencing factor. The aim of this study was to evaluate SVV measured by EIT (SVV) against SVV from pulse contour analysis (SVV) in an experimental animal model of acute lung injury at different lung volumes.
We conducted a randomized controlled trial in 30 anaesthetized domestic pigs. SVV was calculated automatically analysing heart-lung interactions in a set of pixels representing the aorta. Each initial analysis was performed automatically and unsupervised using predefined frequency domain algorithms that had not previously been used in the study population. After baseline measurements in normal lung conditions, lung injury was induced either by repeated broncho-alveolar lavage (n=15) or by intravenous administration of oleic acid (n=15) and SVV was remeasured.
The protocol was completed in 28 animals. A total of 123 pairs of SVV measurements were acquired. Correlation coefficients (r) between SVV and SVV were 0.77 in healthy lungs, 0.84 after broncho-alveolar lavage, and 0.48 after lung injury from oleic acid.
EIT provides automated calculation of a dynamic preload index of fluid responsiveness (SVV) that is non-invasively derived from a central haemodynamic signal. However, alterations in thoracic impedance induced by lung injury influence this method.
通过胸部电阻抗断层成像（EIT）进行功能成像，是一种连续评估中心脑卒中量变化（SVV）以指导液体治疗的非侵入性方法。早期可获得的数据来自于没有因胸部阻抗变化而导致损伤的健康肺部，而胸部阻抗变化可能是一个影响因素。本研究旨在评估在不同肺容积的急性肺损伤实验动物模型中，EIT 测量的 SVV（SVV）与脉搏轮廓分析（SVV）的 SVV 进行比较。
我们在 30 只麻醉的家猪中进行了一项随机对照试验。SVV 通过自动分析代表主动脉的一组像素的心肺相互作用来计算。每次初始分析都是使用以前未在研究人群中使用的预定义频域算法自动和无监督进行的。在正常肺条件下进行基线测量后，通过重复支气管肺泡灌洗（n=15）或静脉注射油酸（n=15）诱导肺损伤，并重新测量 SVV。
28 只动物完成了方案。共采集了 123 对 SVV 测量值。健康肺中 SVV 和 SVV 之间的相关系数（r）为 0.77，支气管肺泡灌洗后为 0.84，油酸引起的肺损伤后为 0.48。
EIT 提供了一种自动计算液体反应性的动态前负荷指数（SVV）的方法，该方法是从中心血流动力学信号无创获得的。然而，肺损伤引起的胸部阻抗变化会影响这种方法。
