Lung growth and pulmonary function after prematurity and bronchopulmonary dysplasia

Abstract

Bronchopulmonary dysplasia (BPD) still carries a heavy burden of morbidity and mortality in survivors of extreme prematurity. The disease is characterized by simplification of the alveolar structure, involving a smaller number of enlarged alveoli due to decreased septation and a dysmorphic pulmonary microvessel growth. These changes lead to persistent abnormalities mainly affecting the smaller airways, lung parenchyma, and pulmonary vasculature, which can be assessed with lung function tests and imaging techniques. Several longitudinal lung function studies have demonstrated that most preterm-born subjects with BPD embark on a low lung function trajectory, never achieving their full airway growth potential. They are consequently at higher risk of developing a chronic obstructive pulmonary disease-like phenotype later in life. Studies based on computer tomography and magnetic resonance imaging, have also shown that in these patients there is a persistence of lung abnormalities like emphysematous areas, bronchial wall thickening, interstitial opacities, and mosaic lung attenuation also in adult age. This review aims to outline the current knowledge of pulmonary and vascular growth in survivors of BPD and the evidence of their lung function and imaging up to adulthood.

Keywords: bronchopulmonary dysplasia; lung growth; lung structure; preterm birth; pulmonary function.

Figure 1

Trajectories of FEV₁ through childhood in very preterm children with and without bronchopulmonary dysplasia. Slopes in preterm groups represent the rate of lung function decline relative to the term group and show significant declines in lung function trajectory throughout childhood. Solid red and dashed red lines show the 95% CIs for the respective group. FEV₁, forced expiratory volume in 1 s. Reprinted from Simpson et al., copyright (2018), with permission from Elsevier [Color figure can be viewed at wileyonlinelibrary.com]

Figure 2

Thin‐section (A) inspiratory and (B) expiratory computed tomography scans of a 25‐yr‐old nonsmoking male, born weighing 1100 g at 29 weeks gestation, dependent upon supplementary oxygen until 60 days postpartum. The forced expiratory volume in 1 s z score was −4.75. There was moderate‐to‐severe emphysema (arrows; voxel index 46.7%). Reproduced with permission of the © ERS 2021: Wong et al.

Figure 3

Pulmonary structure–function relationship in survivors of BPD and preterm birth. Relationship between lung function (blue rectangles on the top) and lung structure as shown by imaging techniques (green rectangles on the bottom) from infancy till early adult age. The large green arrow from left to right depicts the pulmonary function tests and imaging methods that have been used in previous studies at different ages (i.e., lung ultrasound, rapid thoracoabdominal compression technique, chest CT, etc.). BPD, bronchopulmonary dysplasia; CT, computed tomography. Icons from Macrovector (freepik.com) and VectorStock [Color figure can be viewed at wileyonlinelibrary.com]