Mechanisms of action of endobronchial coil treatment

Background: Endobronchial coil treatment is effective in selected emphysema patients, however, the exact underlying mechanism of action is unknown. Objective: To investigate the role of lung compliance, respiratory muscle strength and dynamic hyperinflation after coil treatment and to identify predictors of response. Methods: Prospective evaluation of severe emphysema patients who were bilaterally treated with coils (PneumRx, USA) in the UMCG hospital (NCT02179125). Testing was performed at baseline and 3 months after coil treatment including lung compliance, MIP/MEP, metronome paced dynamic hyperinflation tests and cycle ergometry. Results: Twenty-four patients were included (11M/13F, mean age 62y, residual volume (RV) 230%pred). Patients significantly improved in static lung hyperinflation, exercise capacity and quality of life. Changes in RV and exercise capacity were significantly associated with a change in dynamic compliance, airway resistance and maximal expiratory pressure. Furthermore, the change in exercise capacity was significantly associated with change in dynamic hyperinflation (Table 1). At baseline, higher RV, higher airtrapping (difference TLC-helium and Bodyplethysmography) and lower functional status (steps/day and Wmax) were predictors of response in RV. Conclusions: Next to decreasing static hyperinflation, improvement of airway resistance and dynamic lung compliance could be underlying mechanisms of action of the endobronchial coil treatment.