Williams E, et al. - Researchers analyzed 30 infants [median (IQR) gestational age of 24.6 weeks] from 2010 to 2016 to estimate the relation of oxygenation, ventilation efficiency and tidal volume requirements with the development of pulmonary interstitial emphysema (PIE) and if a composite gas exchange index could predict death or bronchopulmonary dysplasia (BPD) in affected subjects. They observed higher oxygenation index (OI) and tidal volume in PIE-worst cases, a low ventilation efficiency index (VEI) and ventilation to perfusion ratio. They predicted 80% sensitivity and 100% specificity with death or BPD in infants with OI >11.4 at PIE-worst. An association was found between poor oxygenation and ventilation efficiency in the development of PIE despite increased tidal volumes.