Respiratory function, exercise and ventilation distribution in late adolescence in survivors born extremely preterm or extremely low birth weight

© 2013 Dr. Anne-Marie GibsonRationale: Ongoing respiratory morbidity is a common outcome of extremely preterm birth (EP 2499 g) controls. Objective: To compare results from comprehensive lung function and cardiopulmonary exercise testing, including airflow, lung volumes, diffusing capacity and ventilation efficiency at 18 years of age in the largest geographical cohort of EP/ELBW survivors in the post-surfactant era with NBW controls. Within the EP/ELBW group to compare pulmonary outcomes between those who had BPD and those who did not. In the EP only group to determine the relationships between lung function and exercise capacity with growth restriction in utero. Methods: 208 EP/ELBW survivors (35% had BPD) born in 1991 or 1992, and 153 NBW controls performed spirometry, lung volumes, diffusing capacity, and gas-washout. 114 EP/ELBW subjects (31% had BPD) and 98 NBW controls performed cardiopulmonary exercise tests to a satisfactory level according to standardised guidelines. Main Results: The EP/ELBW group had significant impairments in spirometry, bronchodilator response, airways resistance, ventilation efficiency in the conducting lung zone, residual volume, and diffusing capacity compared with NBW controls. Those who had bronchopulmonary dysplasia in the newborn period had the greatest impairments. Within the EP only group growth restriction was associated with impairments in airflow and diffusing capacity. Being growth restricted and having BPD did not worsen the airflow impairment. On exercise testing EP/ELBW birth was associated with a significant increase in breathing frequency, and significant reductions in peak ventilation, peak expiratory tidal volume and peak inspiratory tidal volume. EP/ELBW participants with BPD had no further impairments in cardiopulmonary variables related to exercise testing compared with EP/ELBW subjects who did not have BPD. Within the EP only group growth restriction was associated with altered ventilatory patterns and greater use of the ventilatory reserve to achieve maximal exercise. Conclusions: EP/ELBW survivors have significant impairments in airflow, air-trapping, diffusion and ventilation efficiency within the lungs. These lung function impairments are more severe in those who had BPD as a neonate. EP/ELBW subjects alter their respiration to achieve maximal oxygen consumption levels comparable to NBW controls. BPD is not associated with further cardiopulmonary exercise impairment. Growth restriction was associated with impairment in airflow and gas exchange and diffusion capacity, this was not associated with BPD