Clinical and histologic evaluation of an indwelling, inflatable, long-termlaryngeal stent in the canine model

OBJECTIVE: The goal was assessment of a revolutionary approach to laryngeal stenting. A radically designed, atraumatic, inflatable, low-pressure, high -volume, endoscopically inserted laryngeal stent for effective intralarynge al support or longterm prevention of aspiration was prospectively evaluated in a canine model to reveal any significant short- and long-term anatomic and functional changes in the larynx. METHODS: A self-sustaining, tube-free, long-term flap tracheostomy was perf ormed in 14 dogs, followed by endoscopic laryngeal stent insertion. The ste nts were inflated, and their intraluminal pressures were monitored daily. T he stenting period ranged between 3 and 46 days (mean 27.4 days). The anima ls were then euthanized, and total laryngectomy was performed. The larynges underwent gross and microscopic examinations, and a grading scale of react ive changes caused by the stent placement was created on the basis of the f indings. RESULTS: Dye studies for aspiration were negative in all animals. Gross fin dings consisted of varying degrees of small ulceration, localized polypoid lesions, and granulomas. Grossly, 9 dogs exhibited small superficial ulcera tion of the true vocal cords and posterior commissure. Six dogs developed m inor polyps or polypoid changes and/or granulomas, respectively. No gross c hanges were seen in 2 of the dogs. Histopathologically, 10 dogs demonstrate d grade I or II histopathologic changes. Only 4 of the dogs exhibited infla mmation extending into the underlying cartilages, grade III. One dog did no t complete the observation period. CONCLUSION: This new stent demonstrated safety and biocompatibility with mi nimal local tissue reaction to its extended long-term placement. Good toler ance to the stent was documented, with minimal side effects similar to thos e that would be observed in human subjects after endotracheal intubation. W hen followed up in human patients, such minimal lesions have not resulted i n significant long-lasting functional impairments. These initial results wo uld indicate that this stent is well tolerated for long-term application an d qualify as the preferred device for both management of aspiration and pos toperative endolaryngeal bolstering support.