Tracheomalacia: an experimental animal model for a new surgical approach.

Tracheomalacia was created by removing the posterior 50% of the circumference of eight cartilage rings (5-6 cm in length) from the intrathoracic trachea in each of 12 piglets while leaving the mucosa intact. In 6 animals an autologous, free tibial periosteal graft was applied over the defect (graft group). The remaining 6 piglets served as the control group. In all animals, a silastic stent was left in the trachea for 2 weeks to prevent immediate tracheal collapse. The presence of tracheomalacia was assessed 6-8 weeks after surgery. At bronchoscopy total tracheal collapse during coughing occurred only in the controls. As the animals went from quiet breathing to coughing, mean intrathoracic pressure increased from 5 to 80 cm H2O in both groups, and average sagittal tracheal diameter decreased by 10% in the graft group and 71% in the controls. During coughing, mean resistance to airflow across the defect increased by 0.005 +/- 0.002 cm H2O/liter/min in the graft group, by 0.083 +/- 0.96 cm H2O/liter/min in the controls (P less than 0.005), and by 0.027 cm H2O/liter/min at the same tracheal level in two normal pigs. At sacrifice 12 weeks postoperatively, bone and collagenized fibrous tissue had been produced by all grafts, without evidence of stricture. This study shows that experimentally induced tracheomalacia can be treated successfully by the application of an autologous periosteal tibial graft, which becomes incorporated into the weakened tracheal wall.