Experimental model of tracheal stenosis with submucosal resection of cartilaginous rings combined with sodium hydroxide instillations.

OBJECTIVE To experimentally develop tracheal stenosis and malacia to test new models of tracheal stents. METHODS We resected three cartilaginous rings from the cervical trachea of dogs in group A (n = 5) and six rings in group B (n = 4) to produce malacia. The mucosa of the region with malacia then received applications of a solution of sodium hydroxide (NaOH) at 23%, and the animals were accompanied with bronchoscopic examinations to observe the development of luminal narrowing of the airway. When the stenosis was of more than 50% or there were minimal signs of ventilatory failure, the animals were sacrificed. The segment of narrowed airway was then collected for histological analysis and calculation of the area of residual lumen in the tracheal segment with stenosis and malacia. RESULTS In histological analysis, fibrosis was found in the submucosa and adventitia, associated with granulomas in the mucosa. The average residual lumen of the segments with stenosis was 9% and 12% in groups A and B, respectively (p> 0.05). CONCLUSION The combination of resection of the cartilaginous rings and the application of 23% NaOH in the respiratory mucosa promoted severe tracheal stenosis, but was associated with loss of animals. Further studies are needed to verify that the isolated use of one of the techniques would be safer and more effective to develop tracheal stenosis.