Tracheal tubes can also be used to deliver oxygen in higher concentrations than found in air, or to administer other gases such as helium, nitric oxide, nitrous oxide, xenon, or certain volatile anesthetic agents such as desflurane, isoflurane, or sevoflurane. Tracheal tubes may also be used as a route for administration of certain medications such as salbutamol, atropine, epinephrine, ipratropium, and lidocaine. Tracheal tubes are commonly used for airway management in the settings of general anesthesia, critical care, mechanical ventilation, and emergency medicine.