EXPANDABLE METALLIC STENTS IN BENIGN TRACHEOBRONCHIAL OBSTRUCTION

Expandable metallic stents offer advantages over previously available techniques for treating benign tracheobronchial stenosis or obstructio n. Endoluminal stent placement offers a rapid and effective means of o pening up narrowed airways, and results in excellent relief of symptom s and improvement in pulmonary function. Because they are delivered in a nonexpanded state using flexible over-wire systems, they can be pla ced using a flexible bronchoscope and can be located in second-order b ronchial branches. Metallic stents have been used to treat benign airw ay obstruction caused by anastomotic narrowing after lung transplantat ion, infection, congenital lesions, tracheobronchial malacia, inflamma tory conditions including relapsing polychondritis, Wegener granulomat osis, and acquired immunodeficiency syndrome, and external compression from benign mediastinal masses or fibrosis. The stents become epithel ialized, which prevents migration and permits ciliary activity to cont inue. Significant complications can occur, including airway inflammati on, stent migration, airway erosion, and stent fracture and collapse, but more serious complications are uncommon. Computed tomography is es sential in imaging patients being considered for stent placement, as i t allows 1) accurate representation of airway anatomy in three dimensi ons, 2) measurement of airway diameter, 3) evaluation of airway anatom y distal to a narrowed segment and invisible to bronchoscopy, 4) demon stration of dynamic changes in airway morphologic features during forc ed exhalation in patients with airway malacia, and 5) demonstration of focal or diffuse air trapping in lung peripheral to the abnormal airw ay. In patients who have had stent placement, computed tomography is v aluable in assessing airway morphologic features and dynamics distal t o the stent, and can be valuable in assessing stent dysfunction.