Software and Operational Concept for EIT-Based regional lung Function monitoring

Electrical Impedance Tomography (EIT) is a non-invasive imaging technique suitable for medical application. Most of the previous investigations have been done under laboratory conditions and only few projects under real hospital environment. This paper presents a novel concept of EIT application for clinical lung ventilation monitoring. A virtual EIT lung ventilation monitor suitable for application in clinical environment was designed and successfully implemented into the GoeMF II EIT device developed in our lab. The software together with its operational concept is described here. The problems of device handling, extraction of physiological relevant information from measurements, and data storage and retrieval are addressed. During data acquisition, comprehensive status information is displayed: the contact of all electrodes to the patient's body, the correctness of the wiring of the electrodes, and properties of electric or magnetic fields that produce noise at electrodes or cables. To give a quick overview about the patients' lung function, dynamic functional images are introduced for the first time with the essential property that their screen display only changes if the patient’s physiological status changes, but not during the breathing steady state condition. Additional evaluation procedures are available for series of EIT images to generate functional images in offline evaluation mode. Four different display windows are available: lung ventilation, shift-in-lung-volume, filling capacity, and pressure-volume relation. The described features of the virtual EIT ventilation monitor will be helpful to optimize the respirator’s parameters for each individual patient.