Monitoring of Perioperative Ventilation Therapy by Electrical Impedance Tomography (EIT) in Clinical Practice

Abstract

Mechanical ventilation ensures adequate oxygenation if ventilation is distributed in proportion to regional lung blood flow. General anesthesia, supine position, tracheal suctioning and intraoperative pulmonary complications lead to atelectasis and an impairment of oxygenation. Unfortunately, in standard clinical routine there is no bedside technique available to monitor regional ventilation in order to determine perioperative respiratory function. The EIT allows a bedside assessment of regional lung ventilation and dynamic evaluation of lung status within each breath. In terms of “proof-of-principle” we used EIT in relevant clinical settings, e.g. spontaneous breathing in different body positions in the recovery room, general anesthesia and mechanical ventilation with and without PEEP during surgery, and ventilation therapy while recovering from anesthesia at the ICU. We investigate the ability of EIT detecting the changes in regional pulmonary ventilation known to occur during perioperative ventilation therapy. EIT confirmed the differences in the distribution of regional ventilation associated with spontaneous breathing and mechanical ventilation together with PEEP or alveolar recruitment during the perioperative period. Accentuated impedance change of dependent lung regions was examined during spontaneous breathing, while there was a shift of ventilation to the non-dependent lung regions after the induction of anesthesia. The effect of PEEP as part of the perioperative ventilation therapy or alveolar recruitment after tracheal suctioning during mechanical ventilation at the ICU can be detected at bedside. In conclusion, the effect of perioperative ventilation therapy can be evaluated by dynamic real-time EIT monitoring. The EIT has the potential to be used as a simple bedside technique for the measurement of pulmonary aeration and ventilation distribution.