2.3. Stent features and endoscopic technique
We have used BD self-expanding stents (ELLA-CS, Hradec Kralove, Czech Republic) which were custom-made according to the patient´s airway size and needs. This stent consists on a polydioxanone monofilament, which is a semi-crystalline polymer that degrades by random hydrolysis. It has its own dedicated delivery system which comprises a hollow plastic guiding tube with an olive at the end. The stent was placed in the operating room under general anesthesia with complete muscle relaxation. Stent insertion was performed with rigid bronchoscopy (RB) and fluoroscopic control. When a concurrent laryngeal lesion was present and the patient had a tracheostomy, the stent was placed thru the stoma with fluoroscopic visualization or direct vision guidance with an ultrathin FB. This procedure proved to be more intricate than the standard RB technique used in most cases. Bronchography was deemed unnecassary for stent positioning so we did not use it. When deployed, the stent has some degree of shape memory and tends to coil achieving its nominal diameter after a few hours. According to the manufacturer instructions, this stent maintains full mechanical strength for the first 6–7 weeks after placement and degrades completely after 14–15 weeks. More detailed biomechanical and physical properties have been described elsewhere (6).