First Real-Time Imaging of Bronchoscopic Lung Volume Reduction by Electrical Impedance Tomography

Background Bronchoscopic lung volume reduction (BLVR) with one-way endobronchial valves (EBV) has better outcomes when the target lobe has poor collateral ventilation, resulting in complete lobe atelectasis. High-inspired oxygen fraction (F I O 2 ) promotes atelectasis through faster gas absorption after airway occlusion, but its application during BLVR with EBV has been poorly understood. We aimed to investigate the real-time effects of F I O 2 on regional lung volumes and regional ventilation/perfusion by electrical impedance tomography (EIT) during BLVR with EBV. Methods Six piglets were submitted to left lower lobe occlusion by a balloon-catheter and EBV valves with F I O 2 0.5 and 1.0. Regional end-expiratory lung impedances (EELI) and regional ventilation/perfusion were monitored. Local pocket pressure measurements were obtained (balloon occlusion method). One animal underwent simultaneous acquisitions of computed tomography (CT) and EIT. Regions-of-interest (ROIs) were right and left hemithoraces. Results Following balloon occlusion, a steep decrease in left ROI-EELI with F I O 2 1.0 occurred, 3-fold greater than with 0.5 ( p < 0.001). Higher F I O 2 also enhanced the final volume reduction (ROI-EELI) achieved by each valve ( p < 0.01). CT analysis confirmed the denser atelectasis and greater volume reduction achieved by higher F I O 2 (1.0) during balloon occlusion or during valve placement. CT and pocket pressure data agreed well with EIT findings, indicating greater strain redistribution with higher F I O 2 . Conclusions EIT demonstrated in real-time a faster and more complete volume reduction in the occluded lung regions under high F I O 2 (1.0), as compared to 0.5. Immediate changes in the ventilation and perfusion of ipsilateral non-target lung regions were also detected, providing better estimates of the full impact of each valve in place. Trial registration: Not applicable.