Frerichs I, Hahn G, Golisch W, Kurpitz M, Burchardi H, Hellige G
Department of Anaesthesiological Research, University of Göttingen, FRG.
Acta Anaesthesiol Scand. 1998 Jul;42(6):721-6. doi: 10.1111/j.1399-6576.1998.tb05308.x.
Electrical impedance tomography (EIT) is a noninvasive technique providing cross-sectional images of the thorax. We have tested an extended evaluation procedure, the functional EIT (f-EIT), to identify the local shifts of ventilation known to occur during the transition between spontaneous, controlled and assisted ventilation modes.
Ten patients scheduled for elective laparotomy were studied in the surgical ward, operating theatre and ICU during spontaneous and different modes of mechanical ventilation. Sixteen ECG electrodes were placed on the circumference of the thorax and connected with an EIT device (APT System Mark I, IBEES, Sheffield, UK). Measurements lasting 180 s were performed and f-EIT images of regional ventilation computed. The geometrical centre of ventilation was determined to quantify the regional distribution of lung ventilation during individual modes of ventilation.
F-EIT confirmed the differences in the distribution of ventilation associated with various modes of artificial ventilation. Accentuated ventilation of the dependent lung regions was observed during spontaneous breathing, whereas a shift of the centre of ventilation to the nondependent regions was found during controlled ventilation. In the course of assisted ventilation a continuous displacement of the centre of ventilation back towards the dependent lung regions, consistent with an increased proportion of spontaneous breathing, was detected. Unassisted spontaneous breathing after weaning from mechanical ventilation resulted in a similar ventilation distribution as during tidal breathing prior to surgery.
F-EIT determined the redistribution of lung ventilation during different modes of mechanical ventilation. We expect that f-EIT will become a useful noninvasive bedside monitoring technique for imaging regional ventilation in pulmonary diseased patients during mechanical ventilation.
电阻抗断层成像（EIT）是一种提供胸部横断面图像的无创技术。我们测试了一种扩展评估程序，即功能性EIT（f-EIT），以识别在自主通气、控制通气和辅助通气模式转换期间已知会发生的局部通气变化。
对10例计划进行择期剖腹手术的患者在外科病房、手术室和重症监护病房进行了自主通气和不同模式机械通气时的研究。在胸部周围放置16个心电图电极，并与一台EIT设备（APT系统Mark I，IBEES，英国谢菲尔德）相连。进行了持续180秒的测量，并计算了区域通气的f-EIT图像。确定通气的几何中心以量化个体通气模式下肺通气的区域分布。
f-EIT证实了与各种人工通气模式相关的通气分布差异。在自主呼吸时观察到下垂肺区通气增强，而在控制通气时发现通气中心向非下垂区偏移。在辅助通气过程中，检测到通气中心持续向下垂肺区移位，这与自主呼吸比例增加一致。机械通气撤机后的自主呼吸导致通气分布与手术前潮式呼吸时相似。
f-EIT确定了不同模式机械通气期间肺通气的重新分布。我们预计f-EIT将成为一种有用的无创床边监测技术，用于在机械通气期间对肺部疾病患者的区域通气进行成像。
