Respiratory support and bronchopulmonary dysplasia in infants born at 22-26 weeks gestation in Sweden, 2004-2007 and 2014-2016.

Aim: To evaluate if increased survival and new ventilation strategies were accompanied by a changed incidence of bronchopulmonary dysplasia (BPD) in Sweden over a decade.

Methods: Data from two Swedish population-based studies of live-born infants with gestational ages (GA) 22-26 weeks, born during 2004-2007 (n=702) and 2014-2016 (n=885), were compared for survival, any BPD, moderate BPD, severe BPD, and BPD/severe BPD or death at 36 weeks postmenstrual age (PMA). Ventilation strategies and interventions were analysed. Any BPD was defined as the use of supplemental oxygen or any respiratory support at 36 weeks PMA, moderate BPD as nasal cannula with <30% oxygen, and severe BPD as ≥30% oxygen, CPAP, or mechanical ventilation.

Results: Survival to 36 weeks PMA increased from 72% to 81%(p<0.001). Total days on mechanical ventilation increased from a median of 9 to 16 days (p<0.001). The high-flow nasal cannula (HFNC) was introduced between the cohorts, and days of CPAP and HFNC increased from 44 to 50 days (p<0.001). Any BPD was unchanged, 65% versus 68%. Moderate BPD increased from 37% to 47%(p=0.003), while incidence of severe BPD decreased from 28% to 23%(p<0.046). Severe BPD or death decreased from 48% to 37%(p<0.001) while any BPD or death remained unchanged at 74 versus 75%.

Conclusion: Even though an increased survival of infants born at 22-26 weeks GA was accompanied by an increased duration of invasive and non-invasive respiratory support, the incidence of any BPD remained unchanged while severe BPD decreased in infants alive at 36 weeks PMA.