Physiologic Outcomes of Prematurity
Bronchopulmonary dysplasia (BPD) is the most common short-term complication of premature birth, and infants with BPD can continue to have impaired lung function into adulthood [24]. Although there have been studies comparing lung function between infants with BPD and those without this diagnosis, there are limited data in preterm infants who are born small for gestational age (SGA). Kim, et al investigated the differences in airway obstruction in term, healthy neonates and preterm neonates with and without BPD using MBW and TBA [25]. No significant differences in Tpef/Te were observed between the term infants, preterm infants with mild/moderate BPD, and preterm infants with severe BPD. However, Tpef/Te was significantly lower in the severe BPD infants compared to the mild/moderate BPD infants, consistent with worse airway obstruction in the former group. LCI was significantly increased in preterm infants compared to term ones, but it did not vary between the infants with no BPD, mild BPD, or severe BPD, even when accounting for SGA status. SGA infants with BPD had a significantly lower Tpef/Te than average for GA matched infants, showing a negative effect of SGA in BPD. These results suggest that SGA status is a risk factor for worse airway obstruction in infants with BPD.
Sex differences in lung function and structure are well known, but studies of sex differences in lung mechanics of preterm neonates are lacking. Kim, et al measured airway pressure and flow in male and female neonates requiring mechanical ventilation for neonatal respiratory distress syndrome, and then used these data to generate a single compartment model to calculate specific elastance (ES) [26]. Male infants had higher ES compared to female infants of matched gestational age and less breath-to-breath variability in ES.  This study suggests that ventilator strategies may need to take sex into account, but further studies with larger cohorts are needed.
0.5. There was no significant difference in any other forced expiratory flow measurements, FRC, or respiratory system compliance between the caffeine treated or untreated groups. When further stratified by BPD diagnosis, differences in lung function were only seen in infants without BPD who had received caffeine. These results indicate that caffeine may have beneficial effects on lung function in addition to its effect on reducing risk of BPD.