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 di lating and augmenting constricting cicatricial lesions. Design: Animal study. Setting: Research facility, tertiary care medical center. Subjects: Thirteen dogs, 3 with laryngo tracheal 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. Ste nts were kept in place for 21 days. After removal, dogs were observed for 2 5 days. Five died of complications of tracheostomy. Main Outcome Measures: Airway diameter measured by endoscopy before the ind uction of stenosis, before the laryngeal splitting procedure, after stent r emoval, and before euthanasia. Results: The lumen increased, then shrank somewhat after stent removal. In 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 si ze increased by 50.0% at stent removal, and in 1 dog surviving to day 46, i t was 17.0% larger. In 5 surviving dogs with air-inflated stents, lumen siz e was 39.0% larger at stent removal and 8.0% larger at day 46. Histological ly, fibrous tissue developed in the gaps between the splayed margins of the laryngeal cartilages. Conclusions: The larynx may be dynamically expanded. Although the maximal d iameter is not maintained, final cross-sectional areas are larger.