In a recently published study (ref)10 patients with unstable, severe asthma were treated with bronchial thermoplasty of the left lung, while the right lung was used as an internal control. Changes in lung structure and function were assessed with Functional Respiratory Imaging (FRI).
Significant differences between the treatment and control lungs were observed for airway volume (27% and 17% at TLC and FRC, respectively) as well as for the change in airway volume between FRC and TLC (48% in treatment lung and 5% in control lung). This suggests that in addition to a static improvement in airway volume, treatment is associated with significant improvements in lung compliance. The differences in the ratio of distal airway volume to lung volume also reached significance. There was a trend towards correlation between the improvement in airway volume at TLC and improvement in symptoms. No effect was observed on airway wall thickness or air trapping.
Conclusions are that bronchial thermoplasty increases the luminal airway volume on the treated side compared to the control lung, and that FRI is a very useful technique to measure the effects of BT treatment.