Original articleRisk factors for the development of bronchopulmonary dysplasia: a case-control study
Introduction
Bronchopulmonary dysplasia (BPD) was first described by Northway and colleagues in 1967 as a lung injury in preterm infants resulting from oxygen and mechanical ventilation (1). With advances in neonatal care over the past decades, BPD is now frequently seen in infants with very low birth weight who initially had minimal or no lung disease and who develop increasing oxygen and ventilatory requirements over the first several weeks of life. Many of these patients require supplementary oxygen upon discharge 4 home (2).
The overall incidence of BPD in preterm newborns who require mechanical ventilation at birth has been reported to be approximately 20%, and 15–47% in those infants weighting <1,500 g at birth 3, 4, 5. In our institution a 43% incidence of BPD in infants with birth weight <1,500 g has been reported by Cardona et al. (6), with an increase in incidence to 52% in those infants weighing <1,000 g at birth (6).
The mortality of patients with BPD has been reported to be between 30 and 40% (7). The main causes of death in this group of patients are respiratory failure, systemic infections and cor pulmonale (7). Those patients who survive the first month of life have a 30% increased risk of dying in the first year of life (7).
Patients with BPD have more frequent respiratory infections during the first 2 years of life and an increased frequency of bronchial hyperactivity has been found in severe cases of BPD, with reports in patients of remission at approximately 8 years of age (7). Neurological development is affected in approximately 40% of patients with BPD 8, 9, 10. Motor, auditory abnormalities and long term disability have been reported in up to 16% of patients 8, 9, 10.
The exact mechanism responsible for the severe alterations in the pulmonary structure and function of the neonate with BPD is still unknown. There are many factors, alone or in combination, that have been implicated in the pathogenesis of BPD. Some of them are mechanical trauma and oxygen toxicity; these are crucial factors in the pathogenesis of BPD (11). Another factor that appears to play an important role in the pathogenesis of BPD is inflammation (alone or in association with infection, and pulmonary edema resulting from PDA or excess fluid administration). The presence of maternal chorioamnionitis has also been associated with an increased risk of BPD (11).
The epidemiology of BPD has been well studied in industrialized nations; however, studies to identify risk factors associated with BPD in premature neonates in developing countries is lacking. The objective of our study was to identify the main risk factors associated with BPD in a neonatal setting in a tertiary referral center in Mexico City, Mexico.
Section snippets
Subjects and methods
This study was performed at the National Institute of Perinatology, Mexico City, Mexico, from 1996 to 1999. Premature newborns admitted to the neonatal unit and requiring mechanical ventilation for respiratory failure during the study period were included in this case-control study. The cases consisted of infants needing ventilatory assistance during the first days of life who developed BPD defined as oxygen supplementation and an abnormal chest x-ray finding at 28 days of life (12). Control
Results
Between January 1, 1996 and December 31, 1999 44 premature infants with respiratory failure admitted to the neonatal intensive care unit at the National Institute of Perinatology were the subjects of the study. All patients required mechanical ventilation during the first days of life and survived for more than 28 days. Twenty two infants developed BPD and were compared with 22 infants without BPD.
Discussion
Immaturity, barotrauma and oxygen toxicity have been considered the main risk factors for the development of BPD. Nevertheless, these factors do not explain the development of BPD in newborns who only show mild RDS and who do not require mechanical ventilation. As mentioned previously, inflammation, as well as sepsis, pneumonia and PDA, seem to play an important role in the physiopathology of BPD (11).
To our knowledge no previous studies have been published in our patient population to identify
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Phenotypes of Bronchopulmonary Dysplasia in Adults
2020, ChestCitation Excerpt :With the introduction of commercially available exogenous surfactant in the 1980s and the resultant increase in the viability of extremely preterm infants, the form of BPD now termed the “old” form began to be supplanted by a “new” form reflecting the results of a variety of insults to the lung at an earlier stage of lung development.9 Injurious factors believed to be associated with the development of BPD include surgical closure of a patent ductus arteriosus, neonatal sepsis, fluid overload resulting in pulmonary congestion, and barotrauma secondary to mechanical ventilation.10,11 Recently, maternal preeclampsia also has been found to be associated with a higher incidence of BPD, defined as oxygen dependency at 36 weeks’ gestation.12
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