Posterior tracheal wall dysfunction in excessive dynamic airway collapse: reviewing the role of the posterior membranous wall

Aims Excessive dynamic airway collapse (EDAC) is a form of expiratory central airway collapse (ECAC) characterized by excessive inward movement of the posterior tracheal wall during expiration. Although awareness of EDAC has increased, the biological mechanisms underlying posterior wall dysfunction remain poorly understood. This narrative review synthesises current evidence on the anatomy, biomechanics, and clinical relevance of the posterior membranous wall in relation to EDAC. Materials and methods A literature search covering 2014–2024 was conducted using Google Scholar, Scopus, and PubMed. Studies examining the anatomy, biomechanics, imaging, pathology, and management of EDAC were reviewed. Due to limited direct evidence in EDAC, manual searches were also performed for relevant studies from related airway conditions with similar biomechanical or pathological features and outside the specified time frame to provide supporting context. Results The posterior membranous wall is a complex dynamic structure that contributes to normal airway function and mucus clearance. Current evidence does not support trachealis muscle (TM) atrophy alone as the basis of EDAC. Instead, biological factors, including chronic airway inflammation and GERD, and mechanical factors, including prolonged intubation, local compression, obesity, and OSA, may interact to alter posterior wall structure and compliance. Repeated expiratory collapse may further increase mechanical stress, creating a possible vicious cycle of posterior wall dysfunction. Conclusion Posterior wall dysfunction in EDAC may represent a complex functional disorder involving interactions between tissue properties and mechanical forces rather than a single structural defect. This framework highlights the need for direct histological, morphometric, and biomechanical studies to clarify the mechanisms of EDAC and support the development of more targeted approaches. As this conceptual framework has not been directly investigated in EDAC, its proposed mechanisms should be interpreted with caution.