Expiratory central airway collapse in stable COPD and during exacerbations

Abstract

BackgroundTracheal obstruction resulting from expiratory tracheal deformation has been associated with respiratory symptoms and severe airway exacerbations. In chronic obstructive pulmonary disease (COPD), acute exacerbations (AECOPD) create large intrathoracic pressure swings which may increase tracheal deformation. Excessive central airway collapse (ECAC) may be diagnosed when the tracheal area on expiration is less than 50% of that on inspiration. The prevalence of ECAC in AECOPD and its temporal course have not been systematically studied.MethodsWe prospectively recruited healthy volunteers (n = 53), stable outpatients with COPD (n = 40) and patients with hospitalised acute exacerbations of COPD (AECOPD, n = 64). 17 of the AECOPD group returned for repeat evaluation when clinically well at 6–12 weeks. All subjects underwent dynamic 320-slice computed tomography of the larynx and trachea during tidal breathing, enabling quantitation of tracheal area and dimensions (mean ± SD).ResultsNo healthy individuals had ECAC. The prevalence of ECAC in stable COPD and AECOPD was 35% and 39% respectively. Mean tracheal collapse did not differ between stable COPD (57.5 ± 19.8%), AECOPD (53.8 ± 19.3%) and in the subset who returned when convalescent (54.9 ± 17.2%). AECOPD patients with and without ECAC had similar clinical characteristics.ConclusionsTracheal collapse in both stable and AECOPD is considerably more prevalent than in healthy individuals. ECAC warrants assessment as part of comprehensive COPD evaluation and management. Further studies should evaluate the aetiology of ECAC and whether it predisposes to exacerbations.Electronic supplementary materialThe online version of this article (10.1186/s12931-017-0646-2) contains supplementary material, which is available to authorized users.

<p>Thoracic Imaging at Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review</p>

“…In general, most studies discussed imaging biomarkers either as prevalence values of radiological findings in a population of subjects with an exacerbation of COPD, or as quantitative measurements of an imaging feature. A total of 10 of the 51 papers [9][10][11][12][13][14][15][16][17][18] presented quantitative measurements of imaging features at exacerbation. One paper presented quantitative individual patient data, but no cohort averages, 19 and the remaining 40 papers presented prevalence values for established radiological or other features.…”

“…Most of these did not include details of any other imaging features and so are useful only in estimating the frequency of PE at exacerbation. Eleven serial imaging studies [10][11][12][14][15][16][17][18][19]30,31 performed imaging at multiple time-pointsusually at exacerbation and subsequent follow-up (assumed to represent recovery). The follow-up period for the second imaging time-point ranged from several days 17 to 16 months after the initial exacerbation imaging.…”

“…A total of 36 imaging features present during an exacerbation were reported by the included studies (Table S1). Conclusions, summarized in Figure 2, were primarily drawn from the 10 studies [10][11][12][13][14][15][17][18][19]30 where a control group at stable state was present and the study scored three or more points on the Quality Assessment scale.…”

Differences in airway lumen area between supine and upright computed tomography in patients with chronic obstructive pulmonary disease

“…Recently, central airway collapse using expiratory CT has been reported as an important clinical parameter in patients with COPD. Tracheal collapse during exhalation is prevalent in patients with COPD and related to worse St. George's Respiratory Questionnaire (SGRQ) scores and frequent exacerbation in these patients [ 8 , 9 ]. However, only a few reports have shown that expiratory bronchial area and expiratory bronchial collapse can be CT biomarkers that reflect lung function abnormalities in patients with COPD [ 10 , 11 ].…”

Central Airway Collapse, an Underappreciated Cause of Respiratory Morbidity

“…4,[6][7][8] The "E" in ECAC has been described as both expiratory and excessive without consistency. 2,3,9,10 Although this ambiguity may contribute to confusion, both terms describe the same pathologic entity. Excessive dynamic airway collapse refers to an excessive forward displacement of the posterior membranous portion of the tracheal wall due to weakness and atrophy of the longitudinal elastic fibers.…”