Management of difficult intubation.

Appropriate airway management is an essential part of the anaesthetist's role. Difficult intubation, which can now be quantified using the 'Intubation Difficulty Scale', should be anticipated whenever possible. A strategy needs to be developed in order to anticipate problems. The first part of this paper reviews the different factors that contribute to make intubation and/or ventilation difficult. Problems with intubation (or ventilation of the lungs) can be caused by abnormal laryngeal structures (e.g. tumour, stenosis), or by difficulty in seeing the glottis. The clinical history will usually help identify the former problem, while physical examination of the airway is required to reveal either disproportion between the various structures of the airway (e.g. tongue, larynx), and/or difficulties in aligning the oral, pharyngeal, and laryngeal axes. The different techniques used to diagnose these problems are described. The second part of this paper summarizes the algorithms used by the anaesthetist when management of the airway is found difficult. Three situations are considered: (a) anticipated difficult intubation, for which awake fibreoptic intubation would appear to be the technique of choice in the majority of cases, (b) unforeseen difficult intubation in a patient whose lungs can be ventilated; here, various techniques for control of the airway will be briefly described, and (c) both tracheal intubation and lung ventilation are impossible; this is a life-threatening emergency, for which three solutions are proposed. These include use of the laryngeal mask airway, the Combitube, or transtracheal ventilation. These situations will be analysed with the aim of proposing management strategies that always guarantee the safety of the patient.