Introduction: the difficult airway
Difficulty with airway management can be encountered in all anaesthetic subspecialties. A difficult airway may be due to difficulty in mask ventilation, supraglottic device ventilation, tracheal intubation, or all three. Difficult face mask ventilation has a reported incidence of 0.01–5%. Failed intubation has an incidence of 1:2230 in the general population, but this does not take into account the number of attempts, technique or device used, or the degree of skill and experience of the operator.
The cases in this chapter serve as examples of management, based on the clinical experiences of the authors. There is a lack of evidence for specific techniques in those who are truly difficult, and each set of circumstances is unique. However, recent national audits (NAP4), published guidelines, and prominent cases in the media have demonstrated the need for careful airway assessment, planning and communication of airway management, and improved training in airway management techniques.
The development of new airway devices, e.g. indirect and videolaryngoscopes, may provide alternatives in some cases, but there is limited evidence for their use in difficult airways, and designs are still evolving.
In all cases, certain rules apply, despite the variety of approaches:
1 Oxygenation is the priority. Failure to provide it will cause hypoxic brain injury, followed by death
2 Develop an airway strategy to avoid progression to a ‘can’t intubate, can’t ventilate’ (CICV) situation
3 Repeated attempts at airway manipulation cause trauma, oedema, and morbidity. Make your first attempt your best attempt, e.g. optimize direct laryngoscopy through optimal positioning, alignment, and use of adjuncts such as the Oxford Head Elevating Laryngoscopy Pillow™ in obese patients
4 Be aware of the influences of human factors such as task fixation. Since a difficult airway is a rare occurrence, it can lead to denial or reinforcement of a high-risk approach
5 Aim to improve training and personal experience with the wide variety of equipment and techniques in use. Become highly competent in the core airway skills
6 Careful preoperative assessment, planning, and communication are paramount, including backup plans and a plan for extubation. Follow-up and documentation of difficult airways should be thorough
7 National guidelines from the Difficult Airway Society are readily available—know and use them.
Cook TM, Woodall N, and Frerk C; on behalf of the Fourth National Audit Project (2011). Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. British Journal of Anaesthesia, 106, 617–31.
Cook TM, Woodall N, Harper J, and Benger J; on behalf of the Fourth National Audit Project (2011). Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments. British Journal of Anaesthesia, 106, 632–42.
Difficult Airway Society Extubation Guidelines Group: Popat M, Mitchell V, Dravid R, Patel A, Swampilla C, and Higgs A (2012). Difficult Airway Society Guidelines for the management of tracheal extubation. Anaesthesia, 67, 318–40.
Henderson J, Popat M, Latto I, and Pearce A (2004). Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia, 59, 675–94. Also available at: <http://www.das.uk.com/guidelineshome.html>.
Popat M (2009). Difficult airway management. Oxford University Press, Oxford.
Sudheer P and Stacey M (2002). Anaesthesia for awake intubation. British Journal of Anaesthesia CEPD Reviews, 2, 139–43.