The commonest cause of failed intubation is difficulty in viewing the larynx. A failed intubation is defined as inability to intubate the trachea.

Incidence

Difficult intubation = 1 in 20 (grade 3 or 4)

Failure to intubate = 1 in 1000-2000

Can’t intubate, can’t ventilate (CICV) = 1 in 5000

In the emergency setting, the incidence of failure may be higher - with CICV cases occurring as often as 1 in 500.