Expandable metallic
stents offer advantages over previously available techniques for treating benign tracheobronchial
stenosis or obstruction. Endoluminal
stent placement offers a rapid and effective means of opening up narrowed airways, and results in excellent relief of symptoms and improvement in pulmonary function. Because they are delivered in a nonexpanded state using flexible over-wire systems, they can be placed using a flexible
bronchoscope and can be located in second-order bronchial branches. Metallic
stents have been used to treat benign
airway obstruction caused by anastomotic narrowing after
lung transplantation,
infection, congenital lesions, tracheobronchial malacia, inflammatory conditions including
relapsing polychondritis,
Wegener granulomatosis, and
acquired immunodeficiency syndrome, and external compression from benign mediastinal masses or
fibrosis. The
stents become epithelialized, which prevents migration and permits ciliary activity to continue. Significant complications can occur, including airway
inflammation,
stent migration, airway erosion, and
stent fracture and collapse, but more serious complications are uncommon. Computed tomography is essential in imaging patients being considered for
stent placement, as it allows 1) accurate representation of airway anatomy in three dimensions. 2) measurement of airway diameter, 3) evaluation of airway anatomy distal to a narrowed segment and invisible to bronchoscopy, 4) demonstration of dynamic changes in airway morphologic features during forced exhalation in patients with airway malacia, and 5) demonstration of focal or diffuse air trapping in lung peripheral to the abnormal airway. In patients who have had
stent placement, computed tomography is valuable in assessing airway morphologic features and dynamics distal to the
stent, and can be valuable in assessing
stent dysfunction.