Fraction of reverse impedance change (FRIC): a quantitative electrical impedance tomography measure of intrapulmonary pendelluft

Objective. Pendelluft is the movement of air between lung regions, and electrical impedance tomography (EIT) has shown an ability to detect and monitor it. Approach. In this note, we propose a functional EIT measure which quantifies the reverse airflow seen in pendelluft: the Fraction of Reverse Impedance Change (FRIC). Main Results. FRIC measures the fraction of reverse flow in each pixel waveform (as an image) or globally (as a single parameter). Significance. Such a measure is designed to be a more specific measure than previous approaches, to enable comparative studies of the pendelluft, and to help clarify the effect of ventilation strategies.