[Development of a modified Dumon stent for tracheal applications: an experimental study in dogs]

To describe the development of a silicone stent and perform in vivo testing for biocompatibility/applicability in the normal canine trachea.

Four different densities were tested in order to obtain the silicone prototypes. The pressure required for compression considering a contact area of 1 cm(2), and a 30% reduction in diameter was calculated for each density. The best density was 70-75 Shore A hardness. Powdered barium sulfate was added to the silicone to make the stent radiopaque and easily identifiable in radiological imaging. This novel stent presents a corrugated external surface with discontinuous and protruding arcs resembling the tracheobronchial rings (for intercalation and fixation in the lumen of the lower airways), a highly polished inner surface and smooth extremities (to prevent friction-related damage). The prototype considered most appropriate in terms of rigidity and flexibility was bronchoscopically implanted in normal canine tracheas. After eight weeks, the animals were euthanized, and the tracheas were removed for anatomopathological analysis.

There were no postimplantation complications, and none had to be removed. After eight weeks, the devices were found to be well-positioned. Histopathology revealed a well-preserved epithelial basal membrane, foci of denuded epithelium, mild submucosal inflammatory infiltrate with scattered granulation tissue, vascular neoformation, and no microorganisms.

The stent developed proved resistant to mechanical stress, biocompatible in the canine trachea and well-preserved at the study endpoint.