Subglottic wound healing in a new rabbit model of acquired subglottic stenosis

It is difficult to develop models of subglottic stenosis in small animals that ensure reliable stenosis. We therefore sought to establish a new animal model of subglottic stenosis in rabbits and observe subglottic wound healing.

Using a diode laser under endoscopic visualization after anterior tracheal incision, we induced full-thickness injury to the subglottis in 60 rabbits: 20 on the anterior 120 degrees, 20 on the posterior 120 degrees, and 20 circumferentially. The animals were painlessly sacrificed 2 or 4 weeks later, and their gross and histologic findings were compared with those of each other and with those of 16 age-matched nonwounded controls.

Of the 60 animals, 22 died, primarily of acute airway obstruction and mostly in the circumferential group. All of the injured rabbits showed subglottic stenosis compared with controls, ranging from 12% to 56% reduction in cross-sectional area in the 120 degrees injured groups and from 32% to 82% reduction in the 360 degrees injured group. The significant narrowing of the subglottic lumina resulted in substantial early mortality in the circumferential group. Histologic examination showed mucosal ulceration, inflammation, and formation of granulation tissues during the acute phase after wounding, and collapse of the injured cartilage and submucosal thickening and fibrosis at later times.

Subglottic healing and stenosis depend on the extent of cartilaginous injury. This model may be useful for developing methods to treat subglottic stenosis.