Editing Tracheal intubation (section)

===Depressed level of consciousness===
Perhaps the most common indication for tracheal intubation is for the placement of a conduit through which [[nitrous oxide]] or [[volatile anaesthetic|volatile anesthetics]] may be administered. [[General anaesthetic|General anesthetic agents]], [[opioid]]s, and neuromuscular-blocking drugs may [[hypoventilation|diminish]] or even [[apnea|abolish]] the [[Control of respiration|respiratory drive]]. Although it is not the only means to maintain a patent airway during general anesthesia, intubation of the trachea provides the most reliable means of oxygenation and [[Ventilation (physiology)|ventilation]]<ref name=Ezri2007/> and the greatest degree of protection against regurgitation and pulmonary aspiration.<ref name=AHA2005-III/>

Damage to the brain (such as from a massive [[stroke]], [[non-penetrating head injury]], [[Substance intoxication|intoxication]] or [[poison]]ing) may result in a [[Altered level of consciousness|depressed level of consciousness]]. When this becomes severe to the point of [[stupor]] or [[coma]] (defined as a score on the [[Glasgow Coma Scale]] of less than 8),<ref name=ATLS2004CH6/> dynamic collapse of the extrinsic [[Larynx#Extrinsic muscles associated with the larynx|muscles of the airway]] can obstruct the airway, impeding the free flow of air into the lungs. Furthermore, protective airway reflexes such as [[cough]]ing and [[swallowing]] may be diminished or absent. Tracheal intubation is often required to restore patency (the relative absence of blockage) of the airway and protect the tracheobronchial tree from pulmonary aspiration of gastric contents.<ref name=Kabrhel2007/>