Our experience on silicone Y-stent for severe COPD complicated with expiratory central airway collapse

Abstract

Background: Expiratory central airway collapse (ECAC) is abnormal central airway narrowing during expiration. ECAC involves 2 different pathophysiological entities as tracheobronchomalacia and excessive dynamic airway collapse (EDAC). Although the exact cause is unknown, chronic obstructive pulmonary disease (COPD) is frequently accompanied by ECAC. Although there are various publications on the relationship between COPD and ECAC, there are very few data for stent placement in patients with tracheobronchomalacia accompanied severe COPD. We share our results for stenting in ECAC among patients with severe COPD.

Methods: The data in this case series were collected retrospectively. The ECAC diagnosis was made during flexible bronchoscopy with severe COPD. Silicone Y-stents were placed via rigid bronchoscopy under general anesthesia.

Results: A total of 9 patients’ (7 men) data were evaluated with an average age of 67±10.73 years. One patient experienced stent migration on the second day of stenting prompting stent removal. Another patient died 1 month after stenting. Consequently, we evaluated the follow-up data of remaining 7 patients. The changes in forced expiratory volume 1 was not significant for these 7 cases (P=0.51). The modified Medical Research Council (mMRC) score improvement was statistically significant (P=0.03). Functional status improvement was observed in 4 of 7 patients. Of the 7 patients, mean additional follow-up bronchoscopic interventions requirement was 2.2 times.

Conclusions: Our study showed significant decrease in mMRC score with stenting for ECAC in severe COPD. For 2 patients, we experienced severe complications during short-term follow-up period after stenting. Additional follow-up bronchoscopic interventions were required.

Expiratory central airway collapse (ECAC) is defined as abnormal central airway narrowing during expiration.1 Under the definition of ECAC, there are 2 main subgroups. The first group is tracheobronchomalacia (TBM) where, the cartilaginous structures are weak and leads to airway collapse. The second group is excessive dynamic airway collapse (EDAC) where, posterior membranous part of central airways bulges into airway lumen during expiration.1

There are various classifications for TBM. According to etiology, TBM is divided into as congenital (primary) and acquired (secondary) TBM.2 Another classification is according to the severity of malacia with lumen narrowing below 50% is considered to be normal, 50% to 75% is mild, 75% to 90% is moderate, and >90% is severe malacia.3 Afterwards, this classification was found insufficient, and multidimensional classification system Functional status, Extent, Morphology, Origin of the airway abnormality, Severity of airway collapse (FEMOS) was developed.4 FEMOS classification system was based on functional status (F), extent (E), and severity (S) of airway collapse as well as the morphology (M) and origin (O) of the airway abnormality.4

The combined prevalence of TBM and EDAC was reported 4% to 23% in bronchoscopy for various indications.5 In patients with chronic obstructive pulmonary disease (COPD), ECAC prevalence was found 12.7% and 23% by Ikeda et al3 and Jokinen et al,6 respectively. However, these studies are very old and they did not evaluate TBM and EDAC separately. Although there is no data on TBM prevalence in COPD according to current classification, a study reported 22% EDAC prevalence in patients with asthma and COPD.7 However, there is no proven correlation among any pulmonary function parameter related to COPD severity and tracheal collapse.8 In addition, expiratory tracheal collapse has been more frequently observed in patients with COPD and morbid obesity.9 Of 8820 patients, 443 (5%) of them have found to be ECAC, in a cohort study based on computerized tomography (CT) reported by Bhatt et al.10 In the same study, compared with control group, ECAC group reported to have statistically significantly higher pack years smoking and COPD. Patients with ECAC, compared with control group, had worse St George’s Respiratory Questionnaire scores and modified Medical Research Council (mMRC) scale scores, but no significant difference in 6-min walk distance.10 TBM causes symptoms of exertional dyspnea, difficulty in expectorating secretion, and chronic cough.11 There are studies reporting that presence of TBM might be related with frequent exacerbations of COPD resulting in hospitalization.12

Bronchoscopy is considered the gold standard for diagnosis of TBM. A maneuver is needed to see the tracheobronchial collapse, but this maneuver has not been standardized.13 TBM is reported in 1% of routine bronchoscopy. Although the use of dynamic CT in the diagnosis of TBM is reported,14 recent studies showed that 70% to 80% of normal population also met diagnostic criteria of 50% cutoff of airway collapse in dynamic CT.15

The recommended treatment options for TBM are continuous positive airway pressure device (CPAP), tracheobronchoplasty, and silicone stent implantation.13,16,17 However, there is no treatment consensus among these options. Previous studies showed that respiratory symptoms, quality of life, and functional status were improved, in silicone stent implanted patients due to ECAC, in the short term.13,18 Aim of this study is to share the results of silicone stenting for ECAC among patients with severe COPD.