Regional Ventilation and Perfusion During Flow-Controlled Ventilation in Experimental Lung Injury: Assessment from Dual-Energy Computed Tomography

Abstract Purpose Flow-controlled ventilation (FCV) improves lung aeration and gas exchange but may raise intrathoracic pressure, potentially impeding pulmonary perfusion. This study explores radiographical image analysis to detect potential perturbations of regional ventilation-perfusion matching from application of FCV in experimental acute lung injury. Methods We compared FCV adjusted to the 1) minute volume (FCV-MV) and 2) capnography values (FCV-CO 2 ) of volume-controlled ventilation (VCV) at 1:1 inspiratory to expiratory (I:E) ratio in lavage (n = 2) or oleic acid (n = 9) induced porcine lung injury. Transverse, juxtadiaphragmatic dual-energy computed tomography (DECT) images were acquired during uninterrupted mechanical ventilation. The ratio between ventilated gas volume (VGV) and perfused blood volume (PBV) was computed and used as surrogates to assess regional ventilation-perfusion matching. Results Nine (n = 9) animals completed the protocol. Lung aeration increased during expiration in FCV, but the end-expiratory gas volume, mean airway pressure and gas exchange were similar to VCV 1:1. The VGV within the entire transverse section was 5.35 [4.62–8.15] mL in VCV 1:1, 5.45 [4.84–6.18] mL in FCV-MV and 5.78 [4.73–6.41] mL in FCV-CO 2 . The corresponding PBV was 13.62 [12.09–19.01], 14.25 [13.28–20.79] and 17.31 [13.76–19.44] mL. The VGV to PBV ratio was 0.43 [0.29–0.49] in VCV 1:1, 0.32 [0.26–0.40] in FCV-MV and 0.31 [0.28–0.39] in FCV-CO 2 . There were no differences between the modes in any of ten ventro-dorsal, horizontally orientated lung regions. Conclusion Using surrogate volumes of gas and blood computed from DECT images, regional ventilation-perfusion matching in FCV was not different from VCV with 1:1 I:E ratio in experimental acute lung injury.