[Effect of self-expanding bare metal stents of different diameters on the trachea of dogs].

Objective: To study the effect of self-expanding bare metal stents on the trachea of dogs, and therefore to provide useful information for choice of airway stents by interventional physicians. Methods: In this experiment, 8 beagles were randomly divided into 4 groups. Four self-expanding metal stents of different diameters (16, 18, 20 and 22 mm, respectively) were placed in the trachea of these beagles for 3 months and their impacts on normal trachea were observed. Results: In the 16 mm stent group (stent-to-airway diameter ratio 103%), good epithelialization was observed and the tracheal structure had no significant damage. In the 18 mm stent group (stent-to-airway diameter ratio 116%), slight granulation tissues were observed, but the cartilage and outer membrane were normal. In the 20 mm stent group (stent-to-airway diameter ratio 129%), severe granulation tissues were observed. Cartilage was damaged but outer membrane was normal. In the 22 mm stent group (stent-to-airway diameter ratio 142%), no obvious granulation tissues were found. Cartilage was normal, but outer membrane was ruptured. Conclusion: In a certain range, tracheal granulation tissues increased as the stent diameter increased. However, if the stent diameter continued to increase, a decreasing trend of tracheal granulation was observed, but severe tracheal injury by stent expansion force would occur.