Size of the tube also is important. Tubes should be no larger than 7-8 mm in internal diameter for adult males. Tubes should be no larger than 6-7 mm in internal diameter for adult females. 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.