Background:
Bronchial thermoplasty (BT) is a new therapeutic option for severe refractory asthma not controlled despite high dose inhaled corticosteroids plus long-acting bronchodilators and omalizumab in selected cases. Risk of pulmonary atelectasis after BT in severe asthma has been described in literature, but no details have been reported on the possible mechanisms of the complication.
Case presentation:
A 49-year-old male with severe uncontrolled asthma was referred to BT. One hour after the first procedure, acute respiratory failure occurred with PaO2/FiO2 < 300. A CT scan showed atelectasis of the right lower and middle lobes. A new bronchoscopy was performed under non-invasive ventilation; the right lower and middle lobe bronchus were occluded by bronchus-shaped plugs, that were very difficult to remove despite repeated saline washings and fragmentation with forceps. The patient had a rapid resolution of respiratory failure. Four weeks later, 6 hours after the second session of BT, severe bronchospasm occurred with respiratory failure. Chest X-Ray showed atelectasis of the left lower lobe, prompting to perform a new flexible bronchoscopy on non-invasive ventilation. The exam showed again a plug occluding the left lower lobar bronchus, removed with forceps and washings. The histological analysis of the plugs demonstrated the massive presence of fibrin with mucus debris, rare Charcot-Leyden crystals, scattered macrophages, neutrophils, eosinophils and bronchial epithelial cells.
Conclusion:
The originality of our case report is related to the recurrence of bronchial plugging with lobar atelectasis within one and five hours respectively, after two sequential BT procedures. At the histological evaluation the bronchial plugs appeared very different from the typical mucoid asthma plugs, being composed prevalently by fibrin. It can be hypothesized that intense thermal stimulation of the bronchial mucosa may represent a strong boost for inflammation in susceptible patients, with microvascular alteration induced directly by heat or through the release of mediators. Although in severe asthma a risk of atelectasis from the classical asthma mucoid plugs may be expected, the peculiarity of our case resides in the formation of fibrin plugs whose direct correlation with BT should be considered.