When using an oropharyngeal airway it is important to choose the correct size for the patient. Measure from the patient's incisor teeth to the angle of their jaw (Fig 1).

An incorrectly sized Guedel airway may fail to resolve airway obstruction, or even worsen it.

If placed at too light a plane of anaesthesia, a Guedel airway may lead to gagging, laryngospasm or regurgitation.