Acute Effects of Albuterol on Ventilatory Capacity in Children with Asthma

Background: Children with asthma may have a reduced ventilatory capacity, which could lead to symptoms and early termination of a cardiopulmonary exercise test (CPET). The purpose of this study was to examine the effects of short-acting beta agonist (albuterol) administration on estimated ventilatory capacity in children with asthma. Methods: Fifteen children (eleven boys, 10.6 ± 0.9 years) completed spirometry at baseline, after 180 µg of albuterol, and after the CPET in this cross-sectional study. Ventilatory capacity was calculated from forced vital capacity (FVC) and isovolume forced expiratory time from 25 to 75% of FVC (isoFET_25–75) as follows: FVC/2 × [60/(2 × isoFET_25–75)]. Differences in outcome variables between baseline, after albuterol administration, and after the CPET were detected with repeated measures mixed models with Bonferroni post hoc corrections. Results: Estimated ventilatory capacity was higher after albuterol (68.7 ± 21.2 L/min) and after the CPET (75.8 ± 25.6 L/min) when compared with baseline (60.9 ± 22.0 L/min; P = 0.003). Because forced vital capacity did not change, the increased ventilatory capacity was primarily due to a decrease in isoFET_25–75 (i.e., an increase in mid-flows or isoFEF_25–75). Conclusion: Albuterol administration could be considered prior to CPET for children with asthma with relatively well-preserved FEV₁ values to increase ventilatory capacity pre-exercise and potentially avoid symptom-limited early termination of testing.