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.