Bronchodilator response
Consistent with the findings in other
studies18,21,23,27, the EP adolescents with BPD in our
study showed a greater bronchodilator response than those without BPD
after adjusting for potential confounders. In addition, studies also
found that EP children and adolescents had a greater bronchodilator
response than full-term controls18,21. However, we
only found positive bronchodilator test results in 16% of the
adolescents with history of BPD.
A lack of correlation between the degree of bronchial
hyperresponsiveness and atopy and normal levels of exhaled nitric oxide
has been documented in EP children and
adolescents18,28. Therefore, it is thought that EP
children and adolescents have no eosinophilic airway inflammation, as
observed in typical asthma patients. Instead, airway obstruction might
be related to structural changes due to immaturity and perinatal
pulmonary damage induced by ventilation and prolonged use of oxygen.
Over time, these changes could lead to fixed or irreversible airflow
obstruction, which would explain the low rate of positive results in the
bronchodilator test in our study, as reported by other
studies18,21,28. Thus, BPD and asthma share some
similarities in clinical manifestations and lung function, although they
differ in the pathogenesis of bronchial obstruction.