Dynamic tissue expansion of the larynx in a canine model

Objectives: To test whether staged, progressive, monitored, dynamic tissue expansion is possible in the larynx and to evaluate its effectiveness in dilating and augmenting constricting cicatricial lesions. Design: Animal study. Setting: Research facility, tertiary care medical center. Subjects: Thirteen dogs, 3 with laryngotracheal stenosis. Interventions: Dogs underwent laryngeal splits, tracheostomy, and insertion of inflatable stents. In 7 normal dogs, stents were progressively inflated by air in predetermined increments during 11 days. In 3 normal dogs and 3 with laryngotracheal stenosis, stents were gradually expanded by water. Stents were kept in place for 21 days. After removal, dogs were observed for 25 days. Five died of complications of tracheostomy. Main Outcome Measures: Airway diameter measured by endoscopy before the induction of stenosis, before the laryngeal splitting procedure, after stent removal, and before euthanasia. Results: The lumen increased, then shrank somewhat after stent removal. In 2 surviving dogs with laryngotracheal stenosis and water-expanded stents, the lumen was 82.5% larger than baseline at stent removal and 71.0% larger at euthanasia. In 2 surviving normal dogs with water-expanded stents, lumen size increased by 50.0% at stent removal, and in 1 dog surviving to day 46, it was 17.0% larger. In 5 surviving dogs with air-inflated stents, lumen size was 39.0% larger at stent removal and 8.0% larger at day 46. Histologically, fibrous tissue developed in the gaps between the splayed margins of the laryngeal cartilages. Conclusions: The larynx may be dynamically expanded. Although the maximal diameter is not maintained, final cross-sectional areas are larger.