Abstract
Bronchopulmonary dysplasia (BPD) is a chronic lung disease that predominantly affects prematurely born infants. Initially, BPD was described in infants who had suffered severe respiratory failure and required high pressure, mechanical ventilation with high concentrations of supplementary oxygen. Now, it also occurs in very prematurely born infants who initially had minimal or even no signs of lung disease. These differences impact the nature of the lung function abnormalities suffered by “BPD” infants, which are also influenced by the criteria used to diagnose BPD and the oxygen saturation level used to determine the supplementary oxygen requirement. Key also to interpreting lung function data in this population is whether appropriate lung function tests have been used and in an adequately sized population to make meaningful conclusions. It should also be emphasized that BPD is a poor predictor of long-term respiratory morbidity. Bearing in mind those caveats, studies have consistently demonstrated that infants who develop BPD have low compliance and functional residual capacities and raised resistances in the neonatal period. There is, however, no agreement with regard to which early lung function measurement predicts the development of BPD, likely reflecting different techniques were used in different populations in often underpowered studies. During infancy, lung function generally improves, but importantly airflow limitation persists and small airway function appears to decline. Improvements in lung function following administration of diuretics or bronchodilators have not translated into long-term improvements in respiratory outcomes. By contrast, early differences in lung function related to different ventilation modes have led to investigation and demonstration that prophylactic, neonatal high-frequency oscillation appears to protect small airway function.
Highlights
Bronchopulmonary dysplasia (BPD) is a chronic lung disease that predominantly affects prematurely born infants, but can occur in those born at term if they are subjected to high-inflation pressures
Lung function abnormalities as assessed by pulmonary function testing are not part of the current criteria to diagnose BPD, likely reflecting pulmonary function testing is not routinely available in all neonatal intensive care units (NICU). Bearing in mind those caveats, an aim of this review is to describe lung function abnormalities in infants developing or with established BPD and how they change with increasing postnatal age during infancy
Dynamic compliance of the respiratory system on day 1, birth weight and gestational age were all significantly lower in the BPD infants (BPD diagnosed if the infant developed lung disease in the first week after birth, was oxygen dependent at 28 days of age and developed characteristic chest x-ray changes), but there were no significant differences in the interrupter technique results
Summary
Bronchopulmonary dysplasia (BPD) is a chronic lung disease that predominantly affects prematurely born infants, but can occur in those born at term if they are subjected to high-inflation pressures. There is a consensus that infants should be diagnosed as having BPD if infants are oxygen dependent at 28 days after birth [3] They are classified as suffering from mild, moderate, or severe BPD according to their respiratory support requirement at a later date (36 weeks PCA if born prematurely) [3] (Table 1). Lung function abnormalities as assessed by pulmonary function testing are not part of the current criteria to diagnose BPD, likely reflecting pulmonary function testing is not routinely available in all neonatal intensive care units (NICU) Bearing in mind those caveats, an aim of this review is to describe lung function abnormalities in infants developing or with established BPD and how they change with increasing postnatal age during infancy. Infants born at 32 weeks of gestation or greater are assessed at 56 days postnatal age or discharge home, whichever came first
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