Respiratory severity score patterns by birth gestational age among a cohort of extremely preterm infants

Extremely preterm infants often develop respiratory distress syndrome (RDS) after birth, which can lead to mortality or longer-term morbidities such as bronchopulmonary dysplasia (BPD). A hallmark of RDS management includes the provision of respiratory support to maintain lung inflation and support gas exchange in immature lungs. This respiratory support can include less invasive respiratory support strategies such as continuous positive airway pressure, non-invasive positive pressure ventilation, or invasive mechanical ventilation delivered through an endotracheal tube. Respiratory severity score (RSS), the product of mean airway pressure (MAP) and fraction of inspired oxygen (FiO2), is a marker of respiratory illness severity. Among preterm infants, higher RSS within the first month of life is associated with mortality and development of BPD [ 1 ]. Among infants who develop BPD, higher RSS aligns with BPD-associated pulmonary hypertension and less extubation success [ 2 , 3 ]. Previous large cohorts of preterm infants have evaluated trends in FiO2 or mode of respiratory support separately [ 4 , 5 , 6 ]. There is a paucity of published multi-center data in this population showing the typical progression of RSS over time and how this progression differs by birth gestational age (GA). To characterize RSS over time, stratified by birth GA for infants born between 23 – 28 weeks’ GA.