The flexible fiberoptic bronchoscope is a useful instrument for the intubation of patients with an anticipated or unanticipated difficult airway.1 The hallmark of a difficult airway is an abnormal anatomy that precludes the use of the conventional airway management techniques (e.g., face mask and laryngoscope) or maneuverers aimed to align the airway (e.g., jaw thrust and sniffing position).
Any acquired or congenital condition that prevents successful ventilation or intubation by conventional means is a difficult airway. Alternative techniques must be considered for the successful management of these difficult airways. It is imperative in these circumstances to preserve the patient’s spontaneous ventilation while safely preparing for a flexible fiberoptic intubation. A unique advantage of the flexible fiberoptic scope is that its malleability and softness allow it to conform to the patient’s anatomy and to navigate through the airway with a minimal amount of trauma and discomfort. Technical problems and failure to successfully intubate patients using this technique are usually due to a lack of familiarity and expertise with the fiberoptic bronchoscope, using it in the wrong clinical setting, or inadequate patient preparation.
AIRWAY ANATOMY AND INNERVATION
A recognition of the airway’s anatomy is of the utmost importance in the performance of a successful fiberoptic intubation by a nasal or oral approach. A more detailed description of the airway anatomy is provided in Chapters 9 (Essential Anatomy of the Airway), 10 (Basic Airway Management), and 18 (Orotracheal Intubation).
It is important to understand the anatomic innervation of the areas through which the fiberoptic bronchoscope will course during the performance of the procedure. This allows a fiberoptic intubation unhindered by the gag and cough reflexes. The fiberoptic bronchoscope passage through the oral cavity will encounter structures innervated by the glossopharyngeal nerve (e.g., the posterior third of the tongue, the vallecula, the anterior surface of the epiglottis, the walls of the pharynx and the tonsils). The glossopharyngeal nerve can be blocked by topicalization of the oropharyngeal mucosa using benzocaine- or 5% lidocaine-soaked pledgets (i.e., applied to the posterior tongue, tonsils, anterior tonsillar pillars [glossopalatal arches] and posterior tonsillar pillars [glossopharyngeal arches]), the inhalation of aerosolized 4% lidocaine, or directly injecting 5 mL of 2% lidocaine. The transoral approach of injection is achieved by using a spinal needle aimed at the base of the posterior pillar of the tonsil (Figure 28-1).2 Do not inject the local anesthetic solution into the internal carotid artery as its runs at 1 inch lateral and posterior to the tonsil.
Intraoral approach to block the glossopharyngeal nerve. (Used with permission from reference 2).
The fiberoptic bronchoscope next encounters structures innervated by the internal branch of the superior laryngeal nerve. This nerve originates from a branch of the vagus nerve. It provides sensory innervation to the ...