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.
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]
It has been argued that video laryngoscopy is preferable to direct laryngoscopy for guiding tracheal intubation in patients with COVID-19. [12, 13]
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. [14]
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. [15] 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. [16] 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. [17]
-
Bronchoscope with endotracheal tube threaded over shaft. Syringe is ready to inflate endotracheal tube cuff.
-
Bronchoscope with endotracheal tube threaded along shaft. Oxygen tube is shown above the bronchoscope.
-
Tongue is grasped by an assistant. Endotracheal tube is being introduced into the oral cavity without assistance of a guiding oral airway.
-
Bronchoscope has been advanced into the trachea.
-
With the bronchoscope in the trachea, the endotracheal tube is advanced into the airway.
-
Placement of bronchoscope into the oral cavity with endotracheal tube threaded over the shaft of the bronchoscope.
-
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.
-
GlideScope monitor view. Endotracheal tube is visualized superior to the glottic opening.
-
GlideScope monitor view. Endotracheal tube is visualized entering the larynx.
-
Ovassapian intubating airway.
-
View of the anterior portion of right nasal cavity.
-
View of the nasal cavity, passing below the inferior turbinate.
-
View of the nasopharynx. Eustachian tube openings are seen bilaterally.
-
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.
-
Tracheal intubation (fiberoptic-assisted). Video courtesy of Therese Canares, MD, and Jonathan Valente, MD, Rhode Island Hospital, Brown University.
-
Tracheal intubation (direct laryngoscopy). Video courtesy of Therese Canares, MD, and Jonathan Valente, MD, Rhode Island Hospital, Brown University.
