Awake endotracheal intubation can be achieved using a variety of equipment, such as video laryngoscopes, optical stylets, and fiber-optic scopes. Appropriate anesthesia of the airway and sedation can enable any of these techniques to be used successfully.
The commonest method used to perform an awake endotracheal intubation is with a flexible fiberscope, and an awake fiber-optic intubation is regarded as the gold standard for the endotracheal intubation of patients with an anticipated difficult airway. This procedure requires skills and knowledge that should be familiar to all anesthesiologists.
Recently, there have been many advances in regional anesthesia, allowing for more complicated and innovative procedures to be done under regional block techniques; however, not all of these cases can be done solely under regional anesthesia. Often, a combination of regional and general anesthesia is required; therefore, all anesthesiologists must be familiar with awake intubation techniques, especially if the patient has an anticipated difficult airway. Anesthetizing patients with an anticipated difficult airway is often a source of anxiety and trepidation, but appropriate airway topicalization and sedation techniques can create the appropriate conditions for a safe and stress-free procedure for both the patient and the anesthesiologist.
It is difficult to give precise figures on the incidence of difficult airways due to a variety of reasons, including population differences, operator skill variation, operator reporting, and an inconsistency in the definition of a difficult airway. In the general population, the approximate figures for the incidence of Cormack and Lehane laryngoscopy grades 3 and 4 is 10%, difficult intubation is 1%, and difficult bag mask ventilation is 0.08%–5%.1,2,3,4
Endotracheal intubation is usually performed under general anesthesia, but if a difficult airway is anticipated, then this should ideally be done under regional anesthesia (with or without sedation) as this allows the patient to breathe spontaneously, maintain airway patency, and cooperate with the operator. If any untoward difficulties are experienced, then the procedure can be abandoned with minimum risk to the patient. There are obvious exceptions to performing an awake intubation, such as patient refusal, young children, and uncooperative patients (due to confusion or learning disabilities).
To successfully perform an awake endotracheal intubation, one should be familiar with the following:
Sensory innervation of the upper airway
Agents available for topicalization
Application techniques available to topicalize the airway
Regional anesthesia techniques, landmark or ultrasound guided
Safe sedation techniques
SENSORY INNERVATION OF THE AIRWAY
The upper airway is divided into the nasal and oral cavities, the pharynx, and the larynx. The sensory innervation to the upper airway is supplied by the trigeminal, glossopharyngeal, and vagus nerves (Figure 20–1).
Innervation of the upper airway.