Conclusions:
In the preterm population, oscillometry is a feasible and clinically useful supportive test for those unable to perform spirometry or where bronchial hyperresponsiveness is suspected in the presence of normal spirometry results. A bronchodilator response by spirometry and oscillometry reflects related but distinct physiological changes in the airways of those born preterm, and these tests should not be used interchangeably. Our observations that the response to a bronchodilator as measured by oscillometry and spirometry may reflect different aspects of airway physiology warrants further investigation to advance our understanding of preterm lung disease.