Oscillometry and spirometry are not interchangeable when assessing the
bronchodilator response in children and young adults born preterm
Abstract
Introduction: The European Respiratory Society Oscillometry
Taskforce identified that clinical correlates of bronchodilator
responses are needed to advance oscillometry in clinical practice. The
understanding of bronchodilator-induced oscillometry changes in preterm
lung disease is poor. Here we describe a comparison of bronchodilator
assessments performed using oscillometry and spirometry in a population
born very preterm and explore the relationship between
bronchodilator-induced changes in respiratory function and clinical
outcomes. Methods: Participants aged 6-23 born ≤32 (N=288; 132
with bronchopulmonary dysplasia) and ≥37 weeks’ gestation (N=76,
term-born controls) performed spirometry and oscillometry. A significant
bronchodilator response (BDR) to 400mcg salbutamol was classified
according to published criteria. Results: A BDR was identified
in 30.9% (n=85) of preterm-born individuals via spirometry and/or
oscillometry, with poor agreement between spirometry and oscillometry
definitions (k=0.26; 95%CI 0.18 to 0.40, p<0.001). Those born
preterm with a BDR by oscillometry but not spirometry had increased
wheeze (33% vs 11%, p=0.010) and baseline resistance (Rrs
5 z-score mean difference (MD)= 0.86, 95%CI 0.07 to
1.65, p=0.025), but similar spirometry to the group without a BDR (FEV
1 z-score MD= -0.01, 95%CI -0.66 to 0.68,
p>0.999). Oscillometry was more feasible than spirometry
(95% vs 85% (FEV 1), 69% (FVC), p<0.001),
however being born preterm did not affect test feasibility.
Conclusion: In the preterm population, oscillometry is a
feasible and clinically useful supportive test to assess the airway
response to inhaled salbutamol. Changes measured by oscillometry reflect
related but distinct physiological changes to that measured by
spirometry and thus these tests should not be used interchangeably.