Electrical impedance tomography to monitor hypoxemic respiratory failure

Hypoxemic respiratory failure is one of the leading causes of mortality in intensive care. Frequent assessment of individual physiological characteristics and delivering personalized mechanical ventilation settings is a constant challenge for clinicians caring for these patients. Electrical impedance tomography (EIT) is a bedside and radiation-free monitoring device able to assess regional lung ventilation and changes in aeration. Through a thoracic belt with real-time tomographic functional images of the lungs, clinicians can visualize and estimate the distribution of ventilation at different ventilation settings or following procedures such as prone positioning. Several studies have evaluated the performance of EIT to monitor the effects of different mechanical ventilation settings in patients with acute respiratory distress syndrome allowing a more personalized mechanical ventilation. For instance, EIT could help clinicians find the PEEP representing a compromise between recruitment and overdistension and assess the effect of prone positioning on ventilation distribution. The clinical impact of the personalization of mechanical ventilation remains to be explored. Despite inherent limitations such as limited spatial resolution, EIT also offers a unique bedside non-invasive assessment of the regional ventilation changes in the ICU. It is a bedside technology offering the possibility of a continuous, operator-free diagnosis and real-time detection of common problems during mechanical ventilation. This review provides an overview of the functioning of EIT, its main indices, and its performance in monitoring patients with acute respiratory failure. Future perspectives for use in intensive care are also addressed.