Oscillatory Mechanics Response to Inhaled Bronchodilators in Very Preterm Infants: A Retrospective Study

Abstract

To identify short-term repeatability of forced oscillation technique (FOT) measurement of lung function, assess the lung function response to bronchodilators (BDs) by FOT, and prove the concept that only some very preterm infants manifest a change in lung mechanics in response to BD. We retrospectively analyzed respiratory system resistance and respiratory system reactance measured by FOT (Fabian HFOi). The measurement short-term repeatability was assessed in 43 patients on 60 occasions; BD responsiveness was assessed using a different data set, including 38 measurements in 18 infants. The coefficient of repeatability was calculated as twice the SD of differences between measurements performed 15minutes apart. We assessed BD responsiveness by measuring respiratory system resistance and respiratory system reactance before and 15minutes after administering 200 mcg/kg of nebulized salbutamol. A positive response was defined as an improvement in respiratory system resistance or respiratory system reactance greater than the identified coefficient of repeatability. The coefficient of repeatability was 7.5 cmH2O∗s/L (21%) for respiratory system resistance and 6.3 cmH2O∗s/L (21%) for respiratory system reactance. On average, respiratory system resistance did not change significantly following BD administration, though respiratory system reactance increased significantly (from -32.0 [-50.2, -24.4] to -27.9 [-38.1, -22.0] cmH2O∗s/L, P<.001). Changes in respiratory system resistance or respiratory system reactance after BD were greater than the identified coefficient of repeatability in 8 infants (44%) on 13 (34%) occasions. We identified a threshold to assess BD responsiveness by FOT in preterm infants. We speculate that FOT could be used to assess and personalize treatment with BD.