Size of endotracheal tube needed correlates best with the patient s height. Stenosis also could be secondary to foreign body, infection, inflammation, or chemical irritation. Respiratory epithelium is susceptible to injury. Initial edema, vascular congestion, and acute inflammation can progress to ulceration and local infection with growth of granulation tissue. Finally, fibroblast proliferation, scar formation, and contracture can occur and result in stenosis.
Congenital stenosis has two main types, membranous and cartilaginous.
In membranous stenosis, fibrous soft-tissue thickening is caused by increased connective tissue or hyperplastic dilated mucus glands with absence of inflammation. Membranous stenosis usually is circumferential and may extend upward to include the true vocal folds. In cartilaginous stenosis, a thickening or deformity of the cricoid cartilage most commonly occurs, causing a shelflike plate of cartilage and leaving a small posterior opening. Cartilaginous stenosis is less common than membranous stenosis. Acquired subglottic stenosis is secondary to localized trauma to subglottic structures.