Heterogeneous Distribution of Pulmonary Ventilation in Intensive Care Patients Detected by Functional Electrical Impedance Tomography

Electrical impedance tomography (EIT) is a new noninvasive imaging technique which utilizes the different electrical properties of biological tissues to produce cross-sectional images of selected parts of the body. When applied on the thorax, the cyclic fluctuations of electrical impedance of the lung tissue, associated with different air contents of the lungs in the course of the respiratory cycle, can be used to generate derived EIT tomograms which represent the spatial distribution of ventilation in the chosen transverse plane. The corresponding evaluation technique, the functional EIT, was used for the first time to follow the regional ventilation in three intensive care patients. The method was shown (1) to identify the redistribution of inspired air in the lungs associated with controlled ventilation in a patient undergoing elective laparotomy, (2) to follow the improvement of locally impaired lung ventilation in the course of severe pneumonia, and (3) to detect regional reduction of ventilation due to lobar atelectasis with stasis pneumonia in a patient with bronchial carcinoma.