Introduction: Subglottic stenosis (SGS) is among the most common cause of airway obstruction in children, 90% of which results from endotracheal intubation. Endoscopic treatment for mild to moderate stenosis consists of a combination of endoscopic dilation, laser, and steroid injections. A barrier to treatment remains the need for repeat surgeries, which adds morbidity and elevated costs. Tracheal stents have not yet become a mainstream treatment due to severe complication risks such as stent migration, tracheal erosion, and infections. The PROPEL stent, typically used for sinus surgeries, may be a viable adjunct to treatment as it releases mometasone furoate via a bioabsorbable implant. It additionally has a configuration expanding to a diameter similar in size to the pediatric airway.
Methods: In this pilot study, we induced subglottic stenosis in 14 New Zealand white rabbits using endoscopy and a 5mm diameter nylon brush with each bristle length measuring 2.5mm. All rabbits underwent an endoscopic nylon brush procedure to induce mild SGS. After 2 weeks, 9 rabbits had a PROPEL steroid stent inserted into the subglottis. The additional 5 rabbits had a placebo stent inserted with no impregnated steroid. After 4 weeks when the stent dissolved, rabbit airways were analyzed with photo documentation to assess improvement in tracheal stenosis. Subglottic images of each rabbit were positioned and scaled using a nylon brush as a reference point with a known length of 2.5mm. The subglottic stenosis diameter of each image was measured by a blinded researcher.
Results: The average tracheal stenosis after brushing was 7.7% indicating grade 1 SGS on the Cotton-Myer grading system. After the steroid stent placement, the average stenosis was reduced down to 5.4%, a 30% improvement. These findings approached near significance (p=.053) and are further supported qualitatively with reduction in tracheal stenosis after steroid stent placement. After stent placement, clinical stridor improved on lung auscultation.
Conclusion: This initial pilot study performed shows promise of using a steroid eluting stent to improve mild subglottic stenosis in a rabbit animal model. Additional studies are needed for further validation. Limitations of this study include small sample size and variability in image standardization among all rabbits.