Optical oxygen saturation imaging in cellular ex vivo lung perfusion to assess lobular pulmonary function

Ex vivo lung perfusion (EVLP) is an emerging tool to evaluate marginal lungs in lung transplantation. However, there is no objective metric to monitor lobular regional oxygenation during EVLP. In this study, we developed oxygen saturation (SaO₂) imaging to quantitatively assess the regional gas exchange potential of the lower lobes. Ten porcine lungs were randomly divided into control and donation after circulatory death (DCD) groups (n = 5, each). Lungs were perfused in cellular EVLP for 2 h, and multispectral images were continuously collected from the dorsal sides of the lower lobes. We examined whether lower lobe SaO₂ correlated with PaO₂/FiO₂ (P/F) ratios in lower pulmonary veins (PV). The wet/dry ratio in lower lobes was measured and Monte Carlo simulations were performed to investigate the method's feasibility. There was a significant correlation between lower lobe SaO₂ and the P/F ratio in lower PV (r = 0.855, P < 0.001). The DCD group was associated with lower SaO₂ and higher wet/dry ratio than the control group (P < 0.001). The error of estimated SaO₂ was limited according to Monte Carlo simulations. The developed technology provides a noninvasive and regional evaluative tool of quantitative lobular function in EVLP.