The following is a summary of “Bronchial thermoplasty attenuates bronchodilator responsiveness,” published in the July 2023 issue of Pulmonology by Henry, et al.
Bronchial thermoplasty is a well-established intervention that effectively improves respiratory symptoms and reduces exacerbation rates in patients with uncontrolled severe asthma. However, there was a concern that the reduction in airway smooth muscle resulting from thermoplasty may lead to an impaired response to bronchodilator drugs. For a study, researchers sought to investigate whether bronchial thermoplasty affected the response to bronchodilators in patients with severe asthma.
The study included eight patients with uncontrolled severe asthma who met the clinical criteria for bronchial thermoplasty. Despite receiving optimal treatment, environmental control, and high-dose inhaled corticosteroids and long-acting β2-agonists, these patients continued to have uncontrolled asthma symptoms. Spirometry and oscillometry were used to measure lung function and respiratory mechanics before and after bronchodilator administration (salbutamol, 400 μg), both before the thermoplasty procedure and at least 1 year after.
Consistent with previous research, bronchial thermoplasty did not significantly improve baseline lung function and respiratory mechanics. However, it effectively improved asthma symptoms, as demonstrated by two asthma questionnaires – ACQ-5 and ACT-5. The response to salbutamol, as measured by spirometric parameters such as forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio, remained unaffected by the thermoplasty procedure. Interestingly, there was a significant interaction between thermoplasty and salbutamol for two oscillometric measurements, reactance at 5 Hz (Xrs5) and reactance area (Ax), indicating an attenuated response to salbutamol after thermoplasty.
Bronchial thermoplasty reduced the response to bronchodilator drugs in patients with uncontrolled severe asthma. The result provided physiological evidence of therapeutic efficacy, consistent with the known effect of thermoplasty in reducing airway smooth muscle. Despite the lack of improvement in spirometric measurements, the improvement in asthma symptoms and the reduced response to bronchodilators suggested bronchial thermoplasty may be a beneficial intervention for patients with severe asthma.