3D Finite Element Simulations for the Improvement of Representation of Local Distribution of Air and Ventilation in the Lungs by Electrical Impedance Tomography (EIT)

点击翻译按钮获取中文摘要

Electrical Impedance Tomography (EIT) is a suitable method for continuous monitoring of lung function in mechanical ventilated intensive care patients. Being not associated with any radiation exposure, it is possible to use EIT directly at the bedside. Since EIT allows for the assessment of regional distribution of aeration and ventilation in the lungs, it can provide monitoring of the efficiency of therapeutic interventions such as mechanical ventilation in ARDS patients. Additionally, EIT provides an opportunity for early diagnosis of lung diseases, i.e. asthma or COPD, and principal investigations on distribution of air and ventilation in the lungs.Currently clinically applicable devices use an arrangement of electrodes in a transversal plane at the patients thorax. However, earlier investigations showed an influence of the cranio-caudal position of the electrode plane on the results. One reason is the inhomogeneity of the lung itself. On the other hand, geometrical elements as different thorax and lung shape in different planes or different distances of the planes and corresponding lung segments to the margin of the body and to other organs will influence the results. Therefore, information from different planes is not fully comparable, making the evaluation of cranio-caudal distribution of air and ventilation in the lungs unreliable.The aim of the project is to determine the various influences of the plane position. Based on these data, an approach to a correction will be compiled to improve the validity of the application in patients. Numerical simulations of EIT measurements in several planes on detailed 3D Finite Element Models of human thorax taken from CT data of patients with healthy lungs will be performed. The use of CT data from patients with different body sizes and shapes, age and sex will ensure a wide variety of the models for different applications. The investigations include selected 3D electrode arrangements where electrodes are placed not only in a plane. This is the basis for future application of 3D-EIT which, however, needs further technical developments.The practicability and plausibility of this approach are to be verified by EIT measurements in multiple planes and with selected 3D arrangements of electrodes on healthy volunteers with simultaneous determination of body shape and lung state. After a successful verification, the preconditions for a later validation of the approach on patients with medical indications for EIT as well as CT examinations will be available. If the approach turns out to be effective, a future implementation of the concept into the EIT software for regional lung state and function determination is desirable.