Quantification of pendelluft in electrical impedance tomography data: opening pandora’s box? a literature review of analytical methods

Abstract Introduction. Pendelluft, i.e. the movement of air between different lung regions, has been associated with lung injury and ventilation inefficiencies in mechanically ventilated patients. Electrical impedance tomography (EIT) is the only bedside technology for real-time imaging of pendelluft. However, no universal method exists for measuring and quantifying pendelluft on EIT data. This review aims to evaluate and summarize the methods used to quantify pendelluft, with a focus on EIT analysis techniques. Approach . A search was conducted in three databases: Embase, Web of Science and Medline, using predefined search criteria. Steps for preprocessing and computation of pendelluft were identified. Calculation steps were standardized to enable comparison across studies, and the methods were applied to EIT data to visualize the differences between them. Main results . 19 studies were included, with six unique methods for quantifying pendelluft on EIT data. The methods have some similarities, but mostly quantify pendelluft differently. Preprocessing methods vary greatly among the methods. These methodological differences are reflected in the variability of results when applying the methods to patient data. Significance . Different methods for quantifying pendelluft with EIT exist, which differ considerably in pendelluft quantification and in EIT preprocessing. Further development and consensus on quantification techniques and standardized reporting are necessary for advancing research into pendelluft and its impact, and improving clinical applicability. This highlights a promising research avenue for EIT as bedside modality for monitoring the impact of spontaneous breathing on regional lung mechanics.