Long-term respiratory outcomes following preterm birth

Preterm birth interrupts the normal development of the respiratory system. Taken together with the lung injury that can occur antenatally such as from chorioamnionitis or postnatally by interventions such as mechanical ventilation and oxygen therapy, survivors are at risk of developing long term deficits of their respiratory system. Decrements of lung spirometry have been regularly reported in those born preterm across all gestational ages. Those who develop chronic lung disease of prematurity (also called bronchopulmonary dysplasia) are the most affected, but lung function decrements are also seen in those born at later gestation of between 33 and 36 weeks, a population that generally does not require respiratory support in the neonatal period. Besides spirometry, many other techniques have been used to assess the status of the respiratory system including measurement of static lung volumes, airway resistance and compliance, bronchial hyper-responsiveness, diffusing capacity, exhaled nitric oxide and newer imaging techniques including hyperpolarised 3-helium magnetic resonance imaging. Discussed in this review are the findings from such methods to delineate the respiratory outcomes that occur after preterm birth.