6M Popat,V Mitchell,R Dravid,et al.Difficult airway society guidelines for the management of tracheal extubation[J]. Anaesthesia, 2012,67 (3) :318 - 340.
7Kenneth H Butler,Brian Clyne.Management of the difficult airway:alternative airway techniques and adjuncts[J].Emerg Med Clin N Am,2003,21(2):259-289.
