Obstructive sleep apnoea is associated with dynamic intra-thoracic central airway collapse: results of a 10-year multi-centre retrospective analysis

Background Disproportionate bulging of the pars membranosa into the central airway on expiration, now termed 'excessive dynamic airway collapse' (EDAC), has poorly characterised significance. Despite physiological arguments supporting an association between obstructive sleep apnoea (OSA) and dynamic intra-thoracic central airway collapse, this is unproven. Methods An audit was conducted of patients having had both a dynamic CT chest and a diagnostic polysomnogram between 2009 and 2018 and within 2 years of one another. Dynamic airway collapse was quantified by the presence of EDAC ([greater than or equai to]75% collapse) at any of five sites plus a composite index of mean cross-sectional area (CSA) change. Linear regression models were used to assess associations between pre-defined variables. Results A total of 59 patients was included. Median apnoea-hypopnoea index (AHI) was 13 events/hour (IQR: 5-31 events/hour | range 0-153 events/hour). EDAC was not identified. Median composite dynamic airway collapse index was 18% (IQR: 9-30% | range: 0-63%). Unadjusted and adjusted linear regression analyses demonstrated statistically significant associations between degree of dynamic intra-thoracic central airway collapse and multiple OSA indices. In the adjusted model, every 10% worsening in dynamic airway collapse was associated with an increase in apnoea-hypopnoea index (AHI) of 5 events/hour (95% confidence interval: 0.9-10 events/hour | p = 0.019). No association was found between dynamic airway collapse and symptoms or healthcare utilisation. Conclusions This study supports an association between dynamic intra-thoracic central airway collapse and OSA, despite the failure to identify EDAC, which was likely due to retrospectively audited CT scans not being performed to research standards. Keywords: Obstructive sleep apnoea, Tracheobronchomalacia, Excessive dynamic airway collapse