Distribution of global and regional lung ventilation using electrical impedance tomography before and after cardiac surgery

Abstract

Objective: This study aimed to determine with electrical impedance tomography (EIT) the distribution of lung volume during spontaneous breathing, between the preoperative and postoperative state of cardiac surgery. Material and Methods: This was a cross-sectional study carried out with 38 adult patients who underwent elective cardiac surgery. The distribution of global and regional pulmonary ventilation was determined through EIT, during spontaneous breathing and in a sitting position, before and after cardiac surgery. The global minute tidal variation (MTVglobal) and the regional minute tidal variation (MTVROI) were compared between these two moments, accepting p < 0.05 as a significant difference. Results: In the settings of our study, MTVglobal decreased without statistical significance (p = 0.74). Preoperative and postoperative regional showed substantial differences in ventilation distribution (p = 0.05), being ROI3 the most and ROI2 the least ventilated at both times. When evaluating the change from preoperative to postoperative a decrease in the left zone (ROI2 and ROI4; p = 0.049) and posterior zone (ROI3 and ROI4; p = 0.001) was observed. Conclusions: The EIT findings after cardiac surgery allowed the detection of zones of low ventilation (posterior and left) at risk for pulmonary complications.