Video Laryngoscopy and Fiberoptic-Assisted Tracheal Intubation 

Updated: Feb 28, 2019
Author: Sunil P Verma, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP 

Overview

Background

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, 2]  The differences between direct and indirect laryngoscopy are illustrated in the videos below.

Tracheal intubation (direct laryngoscopy). Video courtesy of Therese Canares, MD, and Jonathan Valente, MD, Rhode Island Hospital, Brown University.
Tracheal intubation (fiberoptic-assisted). Video courtesy of Therese Canares, MD, and Jonathan Valente, MD, Rhode Island Hospital, Brown University.

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 (ET) 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 ET tube is advanced over the fiberoptic bundle into the patient's airway. Once the 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.[3, 4]

Video laryngoscopy is also used with rigid transoral laryngoscopy. Tools such as the Airtraq laryngoscope (Prodol Meditec, Spain), the GlideScope (Verathon, Bothell, WA), and the Pentax-AWS (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.[5, 6]

Indications

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[7, 8, 9, 10] :

  • Micrognathia
  • 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

In January 2019, guidelines on intubation and extubation in the intensive care unit (ICU) were published by the French Society of Anaesthesia and Intensive Care Medicine (SFAR) and the French-Speaking Intensive Care Society (SRLF).[11]

Contraindications

Fiberoptic intubation is contraindicated in patients who need a surgical airway (eg, patients with highly obstructing laryngeal lesions such as cancer). It is also contraindicated in patients with laryngeal trauma, especially those with suspected cricotracheal separation. Fiberoptic intubation is relatively contraindicated in patients with craniofacial trauma who are actively bleeding into the oropharynx.

Outcomes

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 vs 51%) in simulated difficult airway scenarios (ie, cervical spine immobilization and trismus) using medium-fidelity human simulators.[12]

In a Cochrane review assessing videolaryngoscopy against direct laryngoscopy in adult patients requiring tracheal intubation, Lewis et al found that the former may reduce the number of failed intubations, particularly in patients with a difficult airway; that it improves the glottic view; and that it may reduce laryngeal/airway trauma.[13] However, they did not find evidence that video laryngoscopy reduces the number of intubation attempts, lowers the incidence of hypoxia or respiratory complications, or shortens the time required for intubation.

In a subsequent Cochrane review making the same comparison in pediatric patients (excluding neonates), Abdelgadir et al found evidence suggesting that videolaryngoscopy, as compared with direct laryngoscopy, leads to prolonged intubation time and a higher rate of intubation failure, though the quality of this evidence was very low.[14]  They were unable to reach definite conclusions about adverse hemodynamic responses and other adverse effects of intubation in this population or about whether videolaryngoscopy might lead to improved vocal cord view.

A systematic review and meta-analysis by Jiang et al found that video laryngoscopy, as compared with direct laryngoscopy, does not yield better intubation outcomes in emergency and critical patients.[15]

 

Periprocedural Care

Equipment

Equipment required for video laryngoscopy includes the following:

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

Patient Preparation

Anesthesia

This procedure can be performed with the patient either 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 IV sedation to make the procedure more comfortable.

For the awake patient, anesthesia should be provided to the following three regions before 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% or oxymetazoline 0.05% nasal spray, coat a 28-French nasal trumpet with lidocaine 4% jelly and place it in one nasal passage. This should be serially dilated to accommodate a 36-French 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 following three 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, then, 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. This can be done by injecting 2 mL of lidocaine 2% transtracheally.

Positioning

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 the bed elevated almost 90º. If the patient is being intubated under sedation, the traditional supine position with the head in a sniffing position suffices.

 

Technique

Approach Considerations

The choice of endotracheal (ET) tube is important. It is essential that the tube fit properly over the fiberoptic scope. Ideally, the inner diameter of the ET tube should be 3 mm larger than the diameter of the scope.[16]  If the gap between the scope and the tube is too large, threading the tube over the fiberoptic shaft may be difficult, and the tube may get caught on laryngeal structures.[16]

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

Specialized ET tubes can be used for fiberoptic intubation. A Nasal RAE tube (Covidien-Nellcor, Boulder, CO) 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, as well as easier to use for intubation.[17]  This is because of the flexible tip that points toward the center of the lumen, thereby reducing the chances that it will get 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 before starting the procedure so that the patient can cooperate.

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

Awake Nasal Intubation

Dilate and numb the nasal cavity as previously described (see Patient Preparation). Load an appropriately sized ET tube over the shaft of the fiberoptic scope (see the images below).

Bronchoscope with endotracheal tube threaded over Bronchoscope with endotracheal tube threaded over shaft. Syringe is ready to inflate endotracheal tube cuff.
Bronchoscope with endotracheal tube threaded along Bronchoscope with endotracheal tube threaded along shaft. Oxygen tube is shown above the bronchoscope.

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. Views of the nasal cavity are shown in the images below.

View of the anterior portion of right nasal cavity View of the anterior portion of right nasal cavity.
View of the nasal cavity, passing below the inferi View of the nasal cavity, passing below the inferior turbinate.

Advance the scope into the oropharynx (see the first image below). Observe the laryngeal anatomy of the epiglottis, vocal folds, and arytenoid cartilages (see the second and third images below).

View of the nasopharynx. Eustachian tube openings View of the nasopharynx. Eustachian tube openings are seen bilaterally.
View of the larynx from the nasopharynx. Arytenoid View of the larynx from the nasopharynx. Arytenoids are seen posteriorly. Base of tongue is seen anteriorly. Soft palate is anterior and tonsillar fossa is lateral.
View of the larynx. View of the larynx.

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 ET tube over the shaft of the scope into the airway. The tube often gets stuck on the arytenoid cartilages. If the ET tube meets resistance, pull it back slightly, rotate it 90-180º, 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 IV and secure the tube in position with tape.

Nasal Intubation With 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 a Magill forceps (see the image below).

Tongue is grasped by an assistant. Endotracheal tu Tongue is grasped by an assistant. Endotracheal tube is being introduced into the oral cavity without assistance of a guiding oral airway.

Dilate and numb the nasal cavity as previously described (see Patient Preparation). Load an appropriately sized ET tube over the shaft of the fiberoptic scope. 

Pass the scope through the nasal cavity into the nasopharynx. Guide it inferiorly so that it passes between the palate and the 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 ET tube over the shaft of the scope into the airway. Connect the tube to the ventilator.

Oral Intubation With Sedation

Oral intubation is easiest when performed with the patient sedated. The patient can be sedated and 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 the image below).

Ovassapian intubating airway. Ovassapian intubating airway.

Ovassapian recommended placing a lightly lubricated ET tube through the oral airway and then passing the fiberoptic scope through this tube.[16] 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 a Magill forceps. Occasionally, a jaw thrust maneuver must be performed by the assistant.

Pass the scope superior to the tongue into the oropharynx (see the first image below). Pass the bronchoscope between the vocal folds, and use the same technique to guide the ET tube into the airway (see the second image below).

Bronchoscope has been advanced into the trachea. Bronchoscope has been advanced into the trachea.
With the bronchoscope in the trachea, the endotrac With the bronchoscope in the trachea, the endotracheal tube is advanced into the airway.

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 may be employed for 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.

Before starting intubation, thread an appropriately sized ET tube over the 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 need not be extended, because a direct view of the larynx can be obtained. This allows an intubation that is less stimulating to the patient's airway.[5]

Use the screen view to position the tip of the laryngoscope underneath the epiglottis (see the image below). Visualize the arytenoids and true vocal folds on the monitor.

Intubation being performed with GlideScope. The en Intubation being performed with GlideScope. The endoscopist is using the monitor to view the larynx. Patient's head is being held for C-spine precautions.

Insert the ET tube with the stylet into the mouth with the other hand. Note the tip of the tube on the monitor. Insert the ET tube between the vocal folds into the airway (see the image below).

GlideScope monitor view. Endotracheal tube is visu GlideScope monitor view. Endotracheal tube is visualized entering the larynx.

While holding the ET tube in place, remove the stylet and laryngoscope. Connect the ET tube to the ventilator.

Because the neck does not need extension, use of rigid videolaryngoscopy may be beneficial during intubation of trauma patients.[18]

Complications

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 ET tube catches on the arytenoids and attempts are made to pass it forcibly, the tube can kink on itself and actually be passed into the esophagus. This possibility should be suspected when it becomes very difficult to withdraw the scope through the ET tube. In such circumstances, the ET tube and the fiberoptic scope should both be withdrawn, and 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 may be managed by waiting for it to pass or by reapplying topical anesthesia. In this situation, the intubation should be delayed until sufficient topical anesthesia is applied. In some cases, however, laryngospasm may be severe and prevent the patient from ventilating, leading to oxygen desaturation. In this situation, 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 emergency surgical airway.