Fiberoptic bronchoscopes (FOBs) serve many purposes, both diagnostic and therapeutic. Relatively unchanged since their development by Shigeto Ikeda in 1966, FOBs are available in various sizes for different uses and are usually 55 or 60 cm in length.¹ Instruments used solely for intubation tend to be smaller in diameter (1.8 to 4.0 mm) than those used for diagnosis and therapy of pulmonary disease, which facilitate passage of biopsy forceps and other instruments through a larger working channel. The FOB consists of a light source, an insertion cord, and a handle. Generally, light is transmitted to the handle of the scope by fiberoptic bundles in a “universal cord” connected to an external medical-grade endoscopic light source. The light is then transmitted from the handle to the end of the scope by another set of fiberoptic bundles routed through the insertion cord. Also along the length of the insertion cord are control wires, which provide for flexion and extension of the tip of the scope; a hollow working channel that allows for suction, administration of local anesthetic or lavaging fluid, passage of instruments, or insufflation of oxygen; and an image transmission bundle, which is protected by a lens at its distal end. The handle of the FOB contains an eyepiece, a diopter adjustment ring, a control lever connected to the previously mentioned control wires, a suction button, and an access port to the working channel. Many FOBs have integrated cameras that allow for real-time video display on an external monitor. Alternatively, a camera may be attached to the eyepiece.

Intubation using a FOB may be performed on an awake or asleep patient, though in patients with an anticipated difficult airway it is generally accepted that maintaining consciousness and a protected airway until the airway is secured increases the safety of anesthesia.²,³,⁴ Like an optical stylet, the FOB allows the user to move his or her vantage point into the airway, guiding the tip of the instrument to the trachea, then threading the endotracheal tube (ETT) over it into the airway. The technique allows for enhanced maneuverability around even the most difficult anatomy and immediate confirmation of ETT placement.⁵ It can be performed on all age groups through a nasal or oral approach.

Providing adequate anesthesia to the airway is the key to intubating with the FOB in the awake patient. For the nasal approach, anesthesia can be applied topically by coating the nasopharyngeal airways with 2% to 4% lidocaine paste or gel (3 mL). To minimize risk of epistaxis this may be combined with topical vasoconstrictor solution, such as 0.5% phenylephrine or 0.05% oxymetazoline (1 mL). Cotton-tipped applicators can be soaked in local anesthetic solution and placed in the nares, to accomplish the same ends. The glottis should be anesthetized as well, to allow the ETT to be advanced out of the nasopharynx without causing patient discomfort or coughing. For either the nasal or oral approach, this should be accomplished with transtracheal injection of 2 to 3 mL of 2% lidocaine solution through the cricothyroid membrane, or by spraying the same solution through the suction channel of the FOB as the cords are visualized. In addition, topical anesthesia to the larynx and trachea may be accomplished with a nebulized solution of 2% lidocaine (2 to 5 mL).

For the oral approach, anesthesia in the oral cavity can be achieved with a combination of superior laryngeal nerve blocks and topical local anesthetic sprays, gargles, or paste (see chapter 8). Blocking the superior laryngeal nerve (branch of CN X), either transcutaneously above the thyroid cartilage or transmucosally with Krause forceps, provides anesthesia to the glottis above the vocal cords, as well as the laryngeal surface of the epiglottis. The lingual surface of the epiglottis, the oropharyngeal walls, and the posterior tongue can be anesthetized with local anesthetic sprays (such as benzocaine or nebulized lidocaine), pastes, or gels (usually 4% or 5% lidocaine). A transmucosal injection of 1 to 2 mL of 2% lidocaine at the base of the anterior tonsillar pillar blocks the lingual branch of the trigeminal nerve (CN V₃), anesthetizing the anterior twothirds of the tongue. An injection of a similar dose of lidocaine in the gutter between the tongue and the gingivae, at the base of the palatoglossal arch, anesthetizes the lingual
branch of the glossopharyngeal nerve (CN IX), suppressing the gag reflex. With all of these methods of providing topical anesthesia, the cumulative dose of local anesthetic should be quantified, and toxic doses (eg, >5 mg/kg of lidocaine) must be avoided, as absorption from these vascular sites can occur rapidly.

Numerous studies and case series attest to the utility of the FOB in the management of the routine and especially the difficult airway.⁶,⁷,⁸,⁹,¹⁰ The American Society of Anesthesiologists difficult airway algorithm includes a section on awake intubation as well as pathways calling for “Alternative Approaches to Intubation,” which includes use of fiberoptic scopes.¹¹ Although there is no advocated “best” device for use in these situations, use of the FOB is probably the oldest and best-described technique.¹² Surveys of anesthesiologists in the United States indicate that the FOB is the preferred intubation device in the management of the difficult airway.¹³ Further, fiberoptic intubation is associated with greater hemodynamic stability and less morbidity compared with direct laryngosopy.¹⁴ In unanticipated difficult airways, intubation over the bronchoscope can be successfully performed through a laryngeal mask airway (LMA) and around the esophageal tracheal Combitube.³,⁴,¹⁵

The utility of FOB for intubation of patients with suspected or confirmed cervical spine injuries where movement can further damage (transect) the spinal cord is well established. It can be performed without any movement of the cervical vertebrae and allows for evaluation of neurologic function in awake patients throughout and after the procedure.⁴,⁷,⁹ Intraoperatively, the FOB has proven to be useful during a case of accidental tracheal extubation in a patient in the prone position with her neck flexed and pinned in a Mayfield head holder for craniotomy. Use of an LMA or mask ventilation was limited due to the patient’s extreme positioning, but the airway was successfully rescued via fiberoptic intubation.¹⁶

The FOB is also beneficial for patients with known trauma to the airway because it allows placement of the ETT beyond the level of the injury and therefore reduces the risk of creating a false passage.⁴ Furthermore, the FOB is particularly useful in cases of lingual tonsillar hyperplasia, a common cause of airway obstruction and difficult intubation. Ideally, these patients should undergo awake intubation, but in cases of unanticipated lingual tonsillar hyperplasia, a technique successfully using the FOB through the bronchial lumen of a double-lumen ETT and a rigid stylet through the tracheal lumen has been described.¹⁷ In patients with particularly distorted anatomy or severe airway obstruction, other potentially useful adaptations to fiberoptic intubation include the use of guidewires through the working channel of the FOB and “fibercapnic intubation,” which uses CO₂ measurements to confirm placement.¹⁸ The simultaneous use of direct laryngoscopy with FOB may improve the success rate of the technique by displacing soft tissues that can impede the fiberscopic view of the glottis.¹⁹

It is important to note that even during a straightforward awake intubation, the operator performing the procedure may meet resistance while advancing the ETT over the FOB, thus failing tracheal intubation on the first attempt. Video data from a study by Johnson et al²⁰ reveal the ETT tube to be most commonly obstructed by the right arytenoid (42% of all patients undergoing awake intubation) or the interarytenoid soft tissues (11%). Rotating the ETT 90° counterclockwise such that the bevel faces posteriorly often results in successful passage of the tube on subsequent attempts. The authors suggest orienting the ETT in this position, and positioning the FOB in the center of the arytenoids on the initial attempt may increase the success rate and therefore reduce potential laryngeal injury.

Ultra-thin fiberscopes with outer diameters as small as 2.5 mm are available for the pediatric and neonate population.¹,²¹ Fiberoptic intubation has been successfully applied in various pediatric difficult airway situations, such as congenital anomalies including microagnathia,²²

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