Biomechanical Properties of Airway Stents: Implications for Clinical Practice

摘要

In patients with central airway obstruction (CAO), expected results and adverse events after stent insertion are directly related to the biomechanical properties of the various airway stents (Table 1). A thorough understanding of these biomechanical properties, particularly retrievability, stent size, expansive radial force, fatigability, resistance to buckling, and hydrophilic properties, is critical for appropriate stent selection and for prevention of complications. In this editorial, we will address these properties as pertinent to the practice of bronchoscopists caring for patients requiring airway stents. Operators contemplating stent insertion must consider stent retrievability, as airway stents may be required only for a short duration. This is the case in patients with malignant obstruction who respond to chemotherapy and/or radiation therapy or in patients with benign obstruction, such as postintubation tracheal stenosis, when occasionally stents may be successfully removed without stricture recurrence. More importantly, however, stents need to be removed when stent-related complications occur. In fact, stent fracture, excessive granulation tissue, and epithelialization as can be seen with metallic stents (uncovered, partially or fully covered) may result in embedding of the stent in the airway wall, which potentially precludes a safe stent removal. Published literature suggests that self-expandable metallic stents (SEMS) are "difficult" to remove after 3 months in vivo; however, there are case reports of SEMS removal 10 years after insertion.