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

Objectives 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. Study design 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 15 minutes apart. We assessed BD responsiveness by measuring respiratory system resistance and respiratory system reactance before and 15 minutes 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. Results 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 similar to 32.0 [similar to 50.2, similar to 24.4] to similar to 27.9 [similar to 38.1,similar to 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. Conclusions Weidentified 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. (J Pediatr 2022;251:149-55).