Introduction:
Bronchopulmonary Dysplasia (BPD) is a complex, multifactorial disease that can lead to significant long-term respiratory morbidity and neurodevelopmental complications [1-3]. BPD is the only complication of neonatal intensive care that is increasing in frequency [4, 5]. A shift in respiratory management using more non-invasive respiratory support immediately after birth (without surfactant instillation) is associated with reduction in the mechanical ventilation [6-8]. However, the advantages of this practice on long-term respiratory outcome has been questioned [9]. Therefore, further investigation is urgently needed to determine the best respiratory care practices for very premature neonates.
While respiratory practice has changed, so has the pathology of BPD, now characterized by decreased alveolar septation and microvascular development [10]. Accordingly, BPD definitions have evolved to capture this changing pulmonary pathology. Oxygen use at 36 weeks post-menstrual age (PMA) is the most widely adopted BPD definition used [11]. The National Institutes of Health (NIH) National Institute of Child Health and Human Development (NICHD) and the National Heart, Lung, and Blood Institute (NHLBI) developed a severity scale definition based on: 1) the need for O2 for 28 days or more, 2) type of respiratory support, and 3) degree of O2 dependence at 36 weeks PMA [12]. The Canadian network suggested that evaluating infants at 40 wks PMA may be more predictive of respiratory outcome [13]. The study published by Jensen et al and the NICHD Neonatal Research Network (NRN) proposed to define BPD by focus on the mode of respiratory support and not the need for supplemental oxygen in order to predict respiratory morbidity at 18-26 months of age [14]. Evaluating practice changes in the context of all established definitions allows for comparisons between studies to better inform clinical practice and planning of interventional studies.
Given the concurrent evolution in respiratory care practices and BPD definitions, we sought to examine the impact of less surfactant use and and more non-invasive respiratory support on the incidence and severity of BPD in premature infants born at less than 28 weeks gestation from 2010-2018, using four current definitions of BPD to comprehensively examine how the incidence of BPD has changed over time.