Video Laryngoscopy and Fiberoptic-Assisted Tracheal Intubation Technique

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. ^[18]  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. ^[18]

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 (Ring-Adair-Elwyn) 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. ^[19]  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.

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).

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.

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).

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.

In patients with COVID-19, the use of a negative-pressure "tent" to minimize aerosol dispersion during the procedure has been described. ^[20]

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).

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 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 recommended placing a lightly lubricated ET tube through the oral airway and then passing the fiberoptic scope through this tube. ^[18] 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).

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.

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.

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).

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 video laryngoscopy may be beneficial during intubation of trauma patients. ^[21]

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.