Background With advanced pre- and post-natal care, the survival rate of extreme preterm infants has increased significantly. As a result, the incidence of respiratory morbidity and complications has also risen and should require further apprehension during follow up of these premature infants as they grow. Due to the lack of facility and normal reference values for lung function tests in the infant population, data for preterm infants in Taiwan are virtually non-existent. In this study, we investigated respiratory function in preterm and term infants until the age of 18 months. The evolution of longitudinal pulmonary function changes were also investigated.
Materials and methods During the period of October of 2012 to September of 2013, infants with informed consent were enrolled in our birth cohort study. After sedation, respiratory function tests were performed by using JAEGER MasterScreen Paediatric, which obtained measurements for the tidal breathing, passive respiratory mechanism, and forced tidal expiration. Tests were measured in preterm infants at corrected ages of 6, 12, and 18 months and term infants at similar age points.
Results Respiratory function exams were performed in 56 term and 20 preterm infants. Several parameters of the tidal breathing were found to be significantly different between term and preterm infants in the same chorological age. Increased airway resistance and reduced lung compliance were observed in the preterm babies when compared to term infants. Values of maximal expiratory flow at functional residual capacity in preterm infants were also significantly lower than those of term infants.
Discussion Premature babies are known to pose a higher risk for pulmonary developmental anomaly. As shown in our study, most preterm infants demonstrated poor performance in several respiratory function exams despite appearing clinically asymptomatic. With the newly developed technique for measuring forced expiratory flows from raised lung volumes in young infants, it is now possible to better understand the natural history and pathophysiology of young infants who were born prematurely. Additionally, the use of pulmonary function test as a clinical diagnostic tool for diseases such as bronchopulmonary dysplasia will be highly predictive and serves as the primary outcome measures.