Type 2 — extrinsic compression sometimes due to vascular rings
Type 3 — acquired due to chronic infection or prolonged intubation or inflammatory conditions like relapsing polychondritis
The trachea normally dilates slightly during inspiration and narrows slightly during expiration. These processes are exaggerated in tracheomalacia, leading to airway collapse on expiration. The usual symptom of tracheomalacia is expiratory stridor or laryngeal crow.
^ van der Zee DC, Bax NM (2007). "Thoracoscopic tracheoaortopexia for the treatment of life-threatening events in tracheomalacia". Surgical endoscopy21 (11): 2024–5. doi:10.1007/s00464-007-9250-8. PMID 17356936.