Risk factors and neonatal outcomes of pulmonary air leak syndrome in extremely preterm infants: A nationwide descriptive cohort study.

Most extremely preterm infants (EPIs), who were born before 28 weeks of gestation, with pulmonary air leak syndrome (ALS) are symptomatic, often severe, and require drainage. EPIs with severe air leak syndrome (sALS) that require tube drainage or needle aspiration are at high risk of morbidities and mortality. This study aimed to investigate perinatal characteristics, morbidities, and mortality in EPIs with sALS, and to estimate the risk of mortality according to gestational age (GA). A prospective cohort study conducted from 2013 to 2020 compiled the Korean Neonatal Network database to evaluate the incidence, perinatal characteristics, and outcomes of sALS in EPIs born before 28 weeks of gestation. Among 5666 EPIs, the incidence of sALS was 9.4% and inversely related to GA. From this cohort, we compared 532 EPIs with sALS to 1064 EPIs without sALS as controls, matching the subjects by GA and birth weight. Preterm premature rupture of membranes, oligohydramnios, resuscitation after birth, low Apgar scores, repeated surfactant administration, persistent pulmonary hypertension of the newborn, and pulmonary hemorrhage were associated with the development of pneumothorax. The sALS group required a higher fraction of inspired oxygen and more invasive respiratory support at both 28 days of life and 36 weeks of postmenstrual age. The sALS group had a higher incidence of bronchopulmonary dysplasia and major brain injury. The mortality rate was higher in the sALS group than in the control group (55.3% vs 32.5%, P < .001), and the ALS group had a 1.7 times risk of mortality than the control group. More attention should be paid to sALS in EPIs because the frequency of sALS increased as GA decreased, and the risk of mortality was more significant at lower GA.