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 (FO) 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 FO 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 FO 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 FO 1.0 occurred, 3-fold greater than with 0.5 (p < 0.001). Higher FO 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 FO (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 FO.

Conclusions: EIT demonstrated in real-time a faster and more complete volume reduction in the occluded lung regions under high FO (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.