Department of Biomedical Engineering, Furtwangen University, Jakob-Kienzle-Strasse 17, D-78054 Villingen-Schwenningen, Germany.
Crit Care. 2010;14(1):R8. doi: 10.1186/cc8860. Epub 2010 Jan 30.
Lung protective ventilation requires low tidal volume and suitable positive end-expiratory pressure (PEEP). To date, few methods have been accepted for clinical use to set the appropriate PEEP. The aim of this study was to test the feasibility of PEEP titration guided by ventilation homogeneity using the global inhomogeneity (GI) index based on electrical impedance tomography (EIT) images.
In a retrospective study, 10 anesthetized patients with healthy lungs mechanically ventilated under volume-controlled mode were investigated. Ventilation distribution was monitored by EIT. A standardized incremental PEEP trial (PEEP from 0 to 28 mbar, 2 mbar per step) was conducted. During the PEEP trial, "optimal" PEEP level for each patient was determined when the air was most homogeneously distributed in the lung, indicated by the lowest GI index value. Two published methods for setting PEEP were included for comparison based on the maximum global dynamic compliance and the intra-tidal compliance-volume curve.
No significant differences in the results were observed between the GI index method (12.2 +/- 4.6 mbar) and the dynamic compliance method (11.4 +/- 2.3 mbar, P > 0.6), or between the GI index and the compliance-volume curve method (12.2 +/- 4.9 mbar, P > 0.6).
According to the results, it is feasible and reasonable to use the GI index to select the PEEP level with respect to ventilation homogeneity. The GI index may provide new insights into the relationship between lung mechanics and tidal volume distribution and may be used to guide ventilator settings.
肺保护性通气需要小潮气量和合适的呼气末正压（PEEP）。迄今为止，很少有方法被接受用于临床设置合适的 PEEP。本研究旨在测试基于电阻抗断层成像（EIT）图像的全局不均匀性（GI）指数指导的 PEEP 滴定的可行性，以确定通气均匀性。
在一项回顾性研究中，研究了 10 例机械通气下的健康肺患者。通过 EIT 监测通气分布。进行标准化递增 PEEP 试验（PEEP 从 0 至 28 mbar，每步 2 mbar）。在 PEEP 试验中，当肺部空气分布最均匀时，即 GI 指数值最低时，确定每个患者的“最佳”PEEP 水平。根据最大全局动态顺应性和潮气量-顺应性曲线，纳入了两种已发表的 PEEP 设置方法进行比较。
GI 指数法（12.2 +/- 4.6 mbar）和动态顺应性法（11.4 +/- 2.3 mbar，P > 0.6）或 GI 指数法和顺应性-容量曲线法（12.2 +/- 4.9 mbar，P > 0.6）之间的结果无显著差异。
根据结果，使用 GI 指数选择通气均匀性的 PEEP 水平是可行和合理的。GI 指数可能为肺力学和潮气量分布之间的关系提供新的见解，并可用于指导呼吸机设置。
