Electrical impedance tomography to set positive end-expiratory pressure.

Abstract

Purpose of review: To summarize the rationale and concepts for positive end-expiratory pressure (PEEP) setting with electrical impedance tomography (EIT) and the effects of EIT-based PEEP setting on cardiopulmonary function.

Recent findings: EIT allows patient-specific and regional assessment of PEEP effects on recruitability and overdistension, including its impact on ventilation-perfusion (V̇/Q) mismatch. The overdistension and collapse (OD-CL) method is the most used EIT-based approach for PEEP setting. In the RECRUIT study of 108 COVID-19 ARDS patients, the PEEP level corresponding to the OD-CL crossing point showed low overdistension and collapse (below 10% and 5%, respectively) regardless of recruitability. In a porcine model of acute respiratory distress syndrome (ARDS), it was shown that at this crossing point, respiratory mechanics (compliance, ΔP) were consistent, with adequate preload, lower right ventricular afterload, normal cardiac output, and sufficient gas exchange. A recent meta-analysis found that EIT based PEEP setting improved lung mechanics and potentially outcomes in ARDS patients. EIT thus provides critical insights beyond respiratory mechanics and oxygenation for individualized PEEP optimization. EIT-based methods for PEEP setting during assisted ventilation have also been proposed.

Summary: EIT is a valuable technique to guide individualized PEEP setting utilizing cardiopulmonary information that is not captured by respiratory mechanics and oxygenation response alone.