This study is aimed to determine factors leading to obstructive granulation tissue formation after placement of Self-Expandable Metallic Stent (SEMS) in patients with benign tracheal diseases.

From August 2001 to September 2007, patients with benign tracheal stenosis who underwent endoscopic tracheal stent placements at the Chang Gung Memorial Hospital, a university-affiliated hospital in Northern Taiwan, were evaluated.

Definition of airway conditions Dynamic collapse (tracheao-malacia) was defined as tracheal lumen narrowing on expiration under bronchoscopic examination. Structural tracheal stenosis was defined as tracheal stenosis excluding dynamic collapse. Etiologies of structural tracheal stenosis were post-intubation or tracheostomy, post-tuberculosis infection, granulation tissue formation cause previous SEMS re-stenosis, previous SEMS fracture, corrosive injury with stricture, mediastinitis cause airway stricture, and goiter compression.

Obstructive granulation tissue formation after SEMS implantation was defined as granulation tissue obstructing the lumen of the SEMS under bronchoscopic examination, including the proximal and distal ends.

Significant variables, such as structural obstruction airway before SEMS implantation was entered into a forward logistical regression analysis to determine the net effect of each predictor while controlling the net effects of others to obstructive granulation tissue formation. Obstructive granulation tissue formation curves between patients with and those without structural tracheal stenosis before SEMS implantation were compared by log rank test.

Inclusion Criteria:

• age > 18 years,
• benign tracheal obstruction,
• receive Ultraflex metallic stent placement under flexible bronchoscopy.

Exclusion Criteria:

• malignant diseases,
• feasibility to receive surgical treatment or silicon stent placement.

Patients with benign tracheal stenosis who underwent endoscopic tracheal stent placements at the Chang Gung Memorial Hospital, a university-affiliated hospital in Northern Taiwan, were evaluated.

Chest surgeon were routinely consulted to evaluate feasibility of silicon stent placement in benign airway obstruction. All patients in our study were those unsuitable to receive silicon stent placement.