Long-term safety and tolerance of silicone and self-expandable airway stents: An experimental study

Background. A variety of respiratory stents are currently available, but th e ideal airway prosthesis seems far from being recognized. The objective of this study was to verify safety and long-term effect on the bronchial wall of three different types of airway stents. Methods. Twelve healthy adult sheep were divided in three groups, scheduled to receive: (1) bare self-expandable metallic stents (Gianturco); (2) sili cone stents (Dumon); and (3) covered self-expandable synthetic stents (Poly flex). Insertions were performed through a rigid bronchoscope under general anesthesia. Chest roentgenogram was performed 1 and 6 months after surgery , and flexible bronchoscopy after 6 months. Twelve months postoperatively, the animals were killed and a postmortem examination was carried out. Results. All Polyflex stents migrated during the observation period; one la te migration was observed in the Dumon group. Microscopic study showed: (1) Gianturco stents: full-thickness perforation of the bronchial wall covered by a thick layer of a chronic inflammatory infiltrate. Infection by Candid a at the bottom of some ulcerations; (2) Dumon stents: mild bronchial infla mmation (squamous metaplasia, submucosal inflammatory infiltrates; granulom a-like infiltrates). In case of displacement, no significant changes of the previously stented bronchus occurred; and (3) Polyflex stents: no changes of the previously stented bronchi. Conclusions. Gianturco stents proved unsafe in the long term, owing to the risk of severe airway wall damage. The Polyflex stent is well tolerated but presents a high migration rate. Silicone stents show several limitations b ut appear to be well tolerated by the host mucosa. (C) 2000 by The Society of Thoracic Surgeons.