Video Laryngoscopy and Fiberoptic Assisted Tracheal Intubation 

Video laryngoscopy is a form of indirect laryngoscopy in which the clinician does not directly view the larynx. Instead, visualization of the larynx is performed with a fiberoptic or digital laryngoscope inserted transnasally or transorally.^[1] The images from video laryngoscopy can be displayed on a monitor for the clinician, patient, and others to view at the time of the procedure; it can also be recorded. Images are magnified when displayed on the monitor, allowing for detailed examination of the larynx. Video laryngoscopy is the premise of fiberoptic intubation.

Fiberoptic intubation involves threading an endotracheal tube over the shaft of a flexible fiberoptic scope. The scope is passed through the mouth or the nose of the patient, into the pharynx, and through the vocal folds into the patient’s trachea. Upon visual confirmation of tracheal rings and carina, the fiberoptic scope is held steady while the endotracheal tube is advanced over the fiberoptic bundle into the patient's airway. Once the endotracheal tube is in place, the scope is removed, and the patient is ventilated. Fiberoptic intubation is often performed with the endoscopist looking through the eyepiece of the fiberoptic scope. However, connecting the scope to a monitor is often advantageous. In this setting, others can observe the procedure, making it an excellent teaching adjunct.^[2]

Video laryngoscopy is also used with rigid transoral laryngoscopy. Tools such as Airtraq laryngoscope (Prodol Meditec, Spain), GlideScope (Verathon, Bothell, Wash), and Pentax-AWS (Airway Scope; Pentax, Tokyo, Japan) are variations of a rigid laryngoscope with a digital camera that allows view of the larynx on a screen. A rigid laryngoscope accompanied by video laryngoscopy, such as the GlideScope, has been shown to improve the view of the larynx as compared to conventional laryngoscopy.^{[3, 4]}

A study by Blair et al determined that video laryngoscopy significantly improved glottic exposure compared with direct laryngoscopy (97% Cormack-Lehane grade I or II versus 51%, p < 0.01) in simulated difficult airway scenarios (ie, cervical spine immobilization and trismus) using medium-fidelity human simulators.^[5]

Any patient who meets the criteria for intubation can be intubated fiberoptically. However, because of the equipment involved, most clinicians reserve fiberoptic intubation for patients who have a difficult airway. Patients with the following conditions or in the following categories are likely to have a difficult airway:^[6]

• Micrognathia
• Mandibular fracture
• Partially obstructing laryngeal lesions such as papilloma or supraglottitis
• A necessity for awake intubation
• Cervical spine injuries or cervical instability
• Rheumatoid arthritis (or patients unable to extend the neck)
• A history of head and neck radiation
• Trismus
• Craniofacial abnormalities

Fiberoptic intubation is contraindicated in patients who need a surgical airway (eg, patients with highly obstructing laryngeal lesions such as cancer).

Fiberoptic intubation is contraindicated in patients with laryngeal trauma, especially in those with suspected cricotracheal separation.

Fiberoptic intubation is relatively contraindicated in patients with craniofacial trauma who are actively bleeding into the oropharynx.

This procedure can be performed while the patient is awake or sedated. If the patient is likely to have a difficult airway, perform the procedure when the patient is awake, if possible. In some circumstances, the patient may be given mild intravenous sedation to make the procedure more comfortable.

For the awake patient, anesthesia should be provided to the following 3 regions prior to and during the procedure:

• Nasal cavity (if nasal intubation is to be performed)
• Pharynx
• Larynx

Nasal anesthesia is provided by lightly coating the area around the nasal trumpets with lidocaine 4% jelly. After having the patient inhale phenylephrine 1% (Neo-Synephrine) or oxymetazoline 0.05% (Afrin) nasal spray, coat a 28F nasal trumpet with lidocaine 4% jelly and place it in one nasal passage. This should be serially dilated to accommodate a 36F nasal trumpet, if possible.

Pharyngeal anesthesia is delivered by nebulizer. The patient should inhale nebulized 3 mL of lidocaine 4%.

Laryngeal anesthesia can be delivered in one of the 3 following ways:

• Apply 1 mL of 4% lidocaine via the fiberoptic scope channel when the scope is positioned directly above the larynx.
• A bilateral superior laryngeal nerve block can be performed.
• A cotton ball soaked in lidocaine 4% can be used to apply the anesthesia. Grasp the soaked cotton back with Jackson laryngeal forceps. With the tongue grasped, apply the cotton ball transorally to the epiglottic, hypopharynx, and vocal fold mucosal surfaces.

Tracheal anesthesia, though not necessary, can be delivered. Two mL of lidocaine 2% can be injected transtracheally.

• Fiberoptic bronchoscope with light source
• Camera with monitor if intubation is to be projected to screen
• Lidocaine 4%
• Nasal trumpets, 28F and 36F
• Glycopyrrolate 0.2 mg (to be administered intravenously before start of the procedure)
• Endotracheal tubes (see Pearls section for additional information)
• Warmed saline
• Syringe, 12 mL
• Oral airway
• Carbon dioxide detector
• Antifog solution or an alcohol pad
• Suction tubing
• Oxygen with cannula

Patients can be seated or supine for fiberoptic intubation.

If the patient is being intubated awake, the patient should be seated with the head of bed elevated almost 90 degrees.

If the patient is being intubated under sedation, the traditional supine position with the head in a sniffing position suffices.

Awake nasal intubation

Dilate and numb the nasal cavity as described in the anesthesia section above.

Load an appropriately sized endotracheal tube over the shaft of the fiberoptic scope (see images below).

Have the patient inhale a nebulized solution of 4% lidocaine orally.

The endoscopist should stand opposite the patient. The patient should be upright and instructed to breathe through his or her nose.

Remove the nasal trumpet and pass the scope into the nasal cavity.

Alternatively, the nasal trumpet can be cut along its length. In this case, once the scope is passed through the trumpet into the nasopharynx, remove the trumpet from the nose and from around the scope.

Continue to pass the scope underneath the inferior turbinate or between the middle and inferior turbinate. As the scope is passed into the nasopharynx, instruct the patient to take a long breath through the nose. This should depress the palate. The images below depict views of the nasal cavity.

Advance the scope into the oropharynx (see image below).

Observe the laryngeal anatomy of the epiglottis, vocal folds, and arytenoid cartilages (see images below).

Drop 2 mL of lidocaine 4% on the vocal folds through the fiberoptic scope channel if available. The patient may cough.

While the patient inhales, advance the tip of the fiberoptic scope through the true vocal folds.

The tracheal rings and carina should be observed.

Advance the endotracheal tube over the shaft of the scope into the airway.

The endotracheal tube often gets stuck on the arytenoid cartilages. If the endotracheal tube meets resistance, pull the endotracheal tube back slightly, rotate the tube 90-180 degrees, and advance it again.

Confirm tube placement with an adequate end-tidal carbon dioxide monitor reading, auscultation of breath sounds, and misting of the tube with ventilation.

Once the position is confirmed, administer propofol to the patient intravenously and secure the tube in position with tape.

Nasal intubation under general anesthesia

The technique of intubating nasally with the patient under general anesthesia differs only slightly from that of an awake intubation.

Apply topical decongestant before the patient is sedated.

After general anesthesia is induced, mask ventilate the patient in the supine position. An oral airway often makes this easier and also lifts the tongue off the posterior pharyngeal wall, facilitating exposure of the larynx. As in an oral intubation, the tongue can be grasped by an assistant with gauze or Magill forceps (see image below).

Dilate and numb the nasal cavity as described in the anesthesia section above.

Load an appropriately sized endotracheal tube over the shaft of the fiberoptic scope.

Pass the scope through the nasal cavity into the nasopharynx.

Guide the scope inferiorly to pass between the palate and posterior pharyngeal wall.

Advance the fiberoptic scope into the oropharynx.

Observe the laryngeal anatomy of the epiglottis, vocal folds, and arytenoid cartilages.

While the patient inhales, advance the tip of the scope through the true vocal folds.

The tracheal rings and carina should be observed.

Advance the endotracheal tube over the shaft of the scope into the airway.

Connect the endotracheal tube to the ventilator.

Oral sedated intubation

Oral intubation is easiest when performed with the patient sedated. The patient can be sedated and be kept spontaneously breathing if desired. If manual ventilation is possible, the patient may be paralyzed.

The patient is supine during this procedure.

Various airway adjuncts can be used (see image below).

Ovassapian recommends placing a lightly lubricated endotracheal tube through the oral airway and then passing the fiberoptic scope through this.^[7] With this technique, the scope is passed through the center of the intubating airway.

Alternatively, the patient's tongue can be grasped by an assistant with a sponge or Magill forceps. Occasionally, a jaw thrust maneuver needs to be performed by the assistant.

Pass the scope superior to the tongue into the oropharynx (see image below).

Pass the bronchoscope between the vocal folds, and use the same technique to guide the endotracheal tube into the airway (see image below).

Another technique uses a laryngoscope to retract the tongue and epiglottis. For this technique, insert a Mac or Miller laryngoscope into the mouth as is done during a standard intubation. Then, pass the bronchoscope transorally into the larynx and perform the intubation.

Rigid videolaryngoscopy

The GlideScope is one of several rigid laryngoscopes that employ video laryngoscopy. On the distal end of the laryngoscope is a digital video camera with a light source. The images taken by this camera project to an attached small color screen that is placed next to the patient.

Prior to starting intubation, thread an appropriately sized endotracheal tube over the glide scope stylet.

After the patient is sedated, ventilated, and/or paralyzed, place the laryngoscope in the oral cavity and move it over the tongue, past the oropharynx, and above the larynx.

Because of the angle of the laryngoscope, the patient’s head does not need to be extended, as a direct view of the larynx can be attained. This allows for less stimulating intubation to the patient.^[3]

Use the screen view to position the tip of the laryngoscope underneath the epiglottis (see image below).

Visualize the arytenoids and true vocal folds on the monitor.

Insert the endotracheal tube with the stylet into the mouth with the other hand.

Note the tip of the endotracheal tube on the monitor.

Insert the endotracheal tube between the vocal folds into the airway (see image below).

Remove the stylet and laryngoscope while holding the endotracheal tube in place.

Connect the endotracheal tube to the ventilator.

Because the neck does not need extension, use of rigid videolaryngoscopy may be beneficial during intubation of trauma patients.^[10]

The choice of endotracheal tube is important. Most importantly, the endotracheal tube must fit over the fiberoptic scope. Ideally, the endotracheal tube inner diameter should be 3 mm larger than the scope diameter.^[7] If the gap between the scope and endotracheal tube is too large, threading the tube over the fiberoptic shaft may be difficult, and the tube may get caught on laryngeal structures.^[7]

If a nasal intubation is to be performed, use an appropriately sized endotracheal tube that can pass through the patient’s nasal cavity easily. For large males, this usually is no larger than a 7.0 endotracheal tube. This is especially important when the patient is being intubated awake, as the most painful portion of the procedure is advancing the tube through the nasal passage.

Specialized endotracheal tubes can be used for fiberoptic intubation. A Nasal RAE tube (Covidien-Nellcor, Boulder, Colo) is preformed to accommodate standard nasal anatomy. Placing the nasal RAE tube in warmed saline for 5 minutes prior to intubation loosens the bend on the tube so that threading the tube does not damage the fiberoptic channels of the bronchoscope.

Alternatively, a Flexi-Tip tube may be used for intubation. Compared to a standard tube, this tube is easier to thread over the shaft of a bronchoscope into the airway, and easier to use for intubation.^[9] This is because of the flexible tip that points toward the center of the lumen, reducing the incidence of getting caught on the arytenoid cartilage. When the bronchoscope tip fogs up, touch a mucosal surface of the patient to immediately defog it. Alternatively, ask the patient to swallow, which often cleans the tip.

If the procedure is performed with the patient awake, carefully explain everything that will be done prior to starting the procedure so that the patient can cooperate.

If the fiberoptic scope is inserted past the vocal folds into the airway and the endotracheal tube does not pass easily, the endotracheal tube may be caught on the arytenoids. Retract the endotracheal tube 1-2 cm, rotate the tube either 90 or 180 degrees, and try repassing the tube into the airway.

The bronchoscopist should always hold the scope taut to allow for easier maneuvering.

Asking the patient to move his or her head or jaw forward often better exposes the larynx.

Equipment malfunction can be devastating. Ensure that all equipment is working. If using a portable bronchoscope, check that batteries are fully charged.

Rarely, when the endotracheal tube catches on the arytenoids and the tube is forcibly passed, the tube can kink on itself and actually be passed into the esophagus. This should be suspected when it becomes very difficult to withdraw the scope through the endotracheal tube. In this circumstance, the endotracheal tube and the fiberoptic scope should both be withdrawn, the intubation should be repeated.

Stimulating the airway when the patient is inadequately anesthetized with topical lidocaine can induce laryngospasm. Laryngospasm may be mild and pass by waiting or by reapplying topical anesthesia. In this situation, the intubation should be delayed until sufficient topical anesthesia is applied. However, in some cases, laryngospasm may be severe and prevent the patient from ventilating, leading to oxygen desaturation. In these instances, laryngospasm can be broken with positive pressure ventilation or, in severe circumstances, with a paralytic agent.

As with any intubation, failing to obtain the airway may necessitate an emergent surgical airway.