Editing Trachea (section)

===Narrowing===
[[File:Stridor NP OGG 2.ogg|thumb|An example of [[stridor]], which develops when the trachea is narrowed or obstructed]]

A trachea may be [[tracheal stenosis|narrowed or compressed]], usually a result of enlarged nearby lymph nodes; cancers of the trachea or nearby structures; large thyroid [[goitre]]s; or rarely as a result of other processes such as [[aneurysm|unusually swollen blood vessel]]s.<ref name=Davidsons2018 /> Scarring from [[tracheobronchial injury]] or intubation; or inflammation associated with [[granulomatosis with polyangiitis]] may also cause a narrowing of the trachea ([[tracheal stenosis]]).<ref name=Davidsons2018 /> Obstruction invariably causes a harsh breathing sound known as [[stridor]].<ref name=Davidsons2018 /> A camera inserted via the mouth down into the trachea, called [[bronchoscopy]], may be performed to investigate the cause of an obstruction.<ref name=Davidsons2018 /> Management of obstructions depends on the cause. Obstructions as a result of malignancy may be managed with surgery, [[chemotherapy]] or [[radiotherapy]].<ref name=Davidsons2018 />  A stent may be inserted over the obstruction. Benign lesions, such as narrowing resulting from scarring, are likely to be surgically excised.<ref name=Davidsons2018 />

One cause of narrowing is [[tracheomalacia]], which is the tendency for the trachea to collapse when there is increased external pressure, such as when airflow is increased during breathing in or out, due to decreased [[Compliance (physiology)|compliance]].<ref name="Hysinger2016">{{cite journal | vauthors = Hysinger EB, Panitch HB | title = Paediatric Tracheomalacia | journal = Paediatric Respiratory Reviews | volume = 17 | pages = 9–15 | date = January 2016 | pmid = 25962857 | doi = 10.1016/j.prrv.2015.03.002 }}</ref> It can be due to congenital causes, or due to things that develop after birth, such as compression from nearby masses or swelling, or trauma.<ref name="Hysinger2016" /> Congenital tracheomalacia can occur by itself or in association with other abnormalities such as [[bronchomalacia]] or [[laryngomalacia]], and [[tracheoesophageal fistula|abnormal connections between the trachea and the oesophagus]], amongst others.<ref name="Hysinger2016" /> Congenital tracheomalacia often improves without specific intervention; when required, interventions may include [[beta agonist]]s and [[muscarinic agonists]], which enhance the tone of the smooth muscle surrounding the trachea; [[positive pressure ventilation]], or surgery, which may include the placement of a [[stent]], or the removal of the affected part of the trachea.<ref name="Hysinger2016" /> In dogs, particularly miniature dogs and [[toy dogs]], tracheomalacia, as well as [[bronchomalacia]],<ref>{{cite journal | vauthors = Johnson LR, Pollard RE | title = Tracheal collapse and bronchomalacia in dogs: 58 cases (7 /2001-1 /2008) | journal = Journal of Veterinary Internal Medicine | volume = 24 | issue = 2 | pages = 298–305 | date = March 2010 | pmid = 20051001 | doi = 10.1111/j.1939-1676.2009.0451.x | doi-access = free }}</ref> can lead to [[tracheal collapse]], which often presents with a honking goose-like cough.<ref>{{cite journal | vauthors = Maggiore AD | title = Tracheal and airway collapse in dogs | journal = The Veterinary Clinics of North America. Small Animal Practice | volume = 44 | issue = 1 | pages = 117–127 | date = January 2014 | pmid = 24268337 | doi = 10.1016/j.cvsm.2013.09.004 }}</ref>