Effect of prosthetic airway splint on the growing trachea.

Airway splints are now used clinically to treat tracheomalacia and may also have a place in the management of tracheal stenosis. These studies in 5 to 7 Kg piglets were designed to assess the effects of prosthetic airway splints on airway growth and to establish their usefulness in the reconstruction of tracheal defects. Three experimental groups were studied: group I (n = 8). Silastic reinforced Marlex mesh or Vicryl mesh prostheses were placed around 75% of the circumference of a 3 cm segment of trachea. Pigs were sacrificed at 4 months (average weight = 78.9 +/- 9.0 Kg) and the cross-sectional area of trachea was measured. Group II (n = 5). The same prostheses were used to replace the tracheal defect created by excising three rings (50% of tracheal circumference). Tracheas were examined grossly and histologically at sacrifice. Group III (n = 5). Same as Group II except tracheal defect covered by strap muscles. Prostheses placed external to them to prevent airway collapse. Group I had 4% to 14% (mean 8%) decrease from normal cross-sectional area of trachea at site of splint. No airway obstruction and no infection was encountered. Group II, severe airway obstruction, granulation tissue, and infection at site of defect was noted. Group III showed no signs of airway obstruction, no infection, and minimal airway narrowing. Re-epithelialization of the muscle surface in contact with airway occurred in all these animals. Silastic reinforced Marlex or Vicryl splints placed around the intact rapidly growing trachea do not significantly limit its growth. In addition, these synthetic materials appear to be well-tolerated when used to reconstruct tracheal defects if placed over well-vascularized tissue such as muscle.