Introduction: Bronchial thermoplasty is an effective intervention for reducing respiratory symptoms and exacerbations in uncontrolled asthma. A reduction in airway smooth muscle (ASM) is thought to account for these clinical benefits. Yet, an ASM reduction should also translate into an impaired response to bronchodilator drugs.

Objective: Investigate whether thermoplasty decreases the response to a bronchodilator.

Methods: Respiratory mechanics measured by oscillometry were examined pre- and post-bronchodilator (salbutamol, 400 µg) before and after at least 1 year of thermoplasty in 8 patients (7 women) with uncontrolled severe asthma. The IUCPQ Ethics Committee approved the project, and two-way ANOVAs were used to assess the effect of thermoplasty, salbutamol, and their interaction.

Results: Despite improving symptoms based on asthma control questionnaires, thermoplasty yielded no benefits in terms of baseline respiratory mechanics. However, a significant interaction was observed between thermoplasty and salbutamol for 2 oscillometric readouts. The reactance of the respiratory system at 5 Hz (X_rs5) increased from -3.2 ± 2.6 to -1.9 ± 1.9 cmH₂O·s/L in response to salbutamol pre-thermoplasty, versus from -2.8 ± 2.3 to -2.2 ± 1.9 cmH₂O·s/L post-thermoplasty (interaction, p=0.04). Similarly, the reactance area (Ax) decreased from 32.6 ± 29.0 to 12.8 ± 18.2 cmH₂O/L in response to salbutamol pre-thermoplasty, versus 27.2 ± 29.4 to 15.7 ± 20.1 cmH₂O/L post-thermoplasty (interaction, p=0.02).

Conclusion: These results suggested that thermoplasty attenuates the bronchodilator response, representing a physiological evidence of therapeutic efficacy in line with the effect of thermoplasty in reducing ASM.