ELECTRICAL IMPEDANCE TOMOGRAPHY DEVICE AND ELECTRICAL IMPEDANCE TOMOGRAPHY METHOD

摘要

An electrical impedance tomography device includes a plurality of electrodes, a display apparatus, and a control and evaluation unit for reconstructing a matrix of image elements, a spatial distribution of impedance changes in an electrode plane, from measurement signals with a reconstruction algorithm. A time series of matrices are provided from an inhalation and an exhalation that follow. The control unit detects a local impedance change, as a function of a quantity monotonically dependent on average alveolar pressure, as inhalation and exhalation curves from the time series of matrices, to calculate a parameter representing the deviation between the inhalation and exhalation curves as a dissipation value of the image element and to associate the parameter with the image element, to combine the dissipation values of all examined image elements in a dissipation map, and to display the dissipation values with graphical codings dependent on dissipation values of the dissipation map.

主权项

1. An electrical impedance tomography device comprising:
a plurality of electrodes, which can be placed around the thorax of a patient and define an electrode plane; a display device; and a control and analysis unit, which is connected to the electrodes and is configured by programming to supply at least one electrode pair as a feeding electrode pair with an alternating current or with an alternating voltage, to record a voltage signal or current signal as measured signals with a plurality of other electrode pairs from the plurality of electrodes, with other electrode pairs of the plurality of electrode pairs acting consecutively as feeding electrode pairs in order to reconstruct a matrix of image elements, which represents a spatial distribution of impedance changes in the electrode plane, from the measured signals with a reconstruction algorithm, and to repeatedly record measured signals over at least one inhalation and at least one exhalation, which follow each other, and to reconstruct matrices in order to obtain a time series of matrices with impedance changes of the image elements over the at least one inhalation and the at least one exhalation, and the control and analysis unit is furthermore configured to detect the respective local impedance change as a function of a variable, which is strictly monotonically dependent on a mean alveolar pressure, over the at least one inhalation as a local inhalation impedance change curve and over the at least one exhalation as a local exhalation impedance change curve from the time series of the matrices for each image element or a selected set of examined image elements; and configured to calculate a respective parameter representing a deviation between the local inhalation impedance change curve and the local exhalation impedance change curve as a local dissipation value; and configured to associate respective image elements with dissipation values or local dissipation values obtained therefrom by standardization; and configured to combine the local dissipation values of all examined image elements into a dissipation map in an image plane defined by the electrode plane, in which dissipation map graphic codings dependent on the local dissipation values of the image elements are associated with said image elements; and configured to display the dissipation map of the image plane on the display device.