Nasotracheal Intubation

Nasotracheal intubation may be performed in patients undergoing maxillofacial surgery or dental procedures or when orotracheal intubation is not feasible (eg, in patients with limited mouth opening).[1, 2]

Nasotracheal intubation used to be the preferred route for prolonged intubation in critical care units, but nasal damage, sinusitis,[3]  and local abscesses have limited its use. 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).[4]

Because of the necessity of longer and narrower tubes for the nasal route, pulmonary toilet is more difficult and airway resistance is greater. The nasal route in the spontaneously ventilating patient was once considered a technique of choice for emergency operations, but orotracheal intubation under direct vision following the rapid sequence induction of anesthesia is now the technique of choice.

Most commonly, this technique is employed in the operating room for dental procedures and intraoral (eg, mandibular reconstructive procedures or mandibular osteotomies) and oropharyngeal operations. Some authors advocate using nasotracheal intubation for minor otolaryngologic and maxillofacial surgical procedures, maintaining that the technique is underused in current practice.[5]

Other indications include securing the airway in patients with questionable cervical spine stability or severe degenerative cervical spine disease (using the awake fiberoptic intubation technique), patients with intraoral mass lesions or structural abnormalities, and patients with limited mouth opening (eg, trismus).

Absolute contraindications for nasotracheal intubation include the following:

• Suspected epiglottitis
• Midface instability
• Coagulopathy
• Suspected basilar skull fractures
• Apnea or impending respiratory arrest - Any patient with advanced upper-airway obstruction who is apneic or is having difficulties maintaining his or her airway should not be subjected to any form of awake intubation

Relative contraindications for nasotracheal intubation include the following:

• Large nasal polyps
• Suspected nasal foreign bodies
• Recent nasal surgery
• Upper-neck hematoma or infection
• History of frequent episodes of epistaxis
• Prosthetic heart valves (increased risk of bacteremia with tube insertion)

Equipment required for nasotracheal intubation includes the following:

• Endotracheal tube - Nasal RAE (Ring-Adair-Elwyn) tube (see the first image below) or regular endotracheal tube
• Lidocaine jelly or any other water-soluble lubricant
• Magill forceps (see the second image below)
• Afrin spray (oxymetazoline 0.05%)
• Nasal trumpets
• Syringe to inflate the cuff
• Suction
• Intubation equipment - Laryngoscope, GlideScope, fiberoptic scope

Nasal RAE (Ring-Adair-Elwyn) endotracheal tube.

Magill forceps.

Commercial airway device adjuncts are available. The GlideScope Video Laryngoscope (GVL, Verathon Medical Inc., Bothell, WA) intubation system has an established role in routine and difficult orotracheal intubation not only by experienced handlers but also by novices.[6, 7, 8]

Anesthesia

If, on the basis of the physical examination or prior history of intubation, no difficulties are expected in securing the airway, general anesthesia and neuromuscular blockade can be induced. General anesthesia is routinely induced using rapid-acting hypnotic or induction agents (eg, propofol, etomidate, thiopental, ketamine).

After anesthesia induction, assess the ability to carry out mask ventilation before giving neuromuscular blockers (except in the case of rapid sequence induction, when mask ventilation is not attempted, and succinylcholine or rocuronium is administered simultaneous to the hypnotic agent). After the neuromuscular blocker drug is administered and given time to achieve maximal effect, perform direct laryngoscopy or blind intubation.

Lubricants and vasoconstrictors are commonly applied to the nasal passages before the introduction of an endotracheal tube. Various vasoconstrictors are available (eg, cocaine 4% solution [not to exceed 1.5 mg/kg], oxymetazoline 0.05% nasal spray, or phenylephrine nose drops 0.25-1%). The choice of vasoconstrictor usually depends on the anesthetist's preference. Applying lidocaine jelly or water-soluble lubricant allows for smoother advance, as well as better transfer of rotation along the endotracheal tube's length during directional manipulation.

If awake fiberoptic intubation is necessary, prepare the nasal passages as described above. Additionally, in awake or sedated patients, topical anesthesia to the larynx and pharynx is also required. This can be accomplished with a number of techniques, such as transoral application of a local anesthetic agent or use of superior laryngeal nerve block with 4% lidocaine (up to 3 mg/kg) administered transtracheally or sprayed down the fiberscope's lumen intermittently in advance of the scope's passage. Incomplete topical anesthesia not only causes patient discomfort but also makes the procedure much more difficult and may lead to morbidity.

An antisialagogue drug (eg, glycopyrrolate 0.2-0.3 mg IV) is administered to improve the visualization of the field. Small amounts of sedation are advocated as well, with the caveat that sedation is not a substitute for a well-anesthetized airway.[9]

Positioning

For the induction of general anesthesia, the patient should be in the supine position.

If awake fiberoptic intubation (or any other awake intubation) is pursued, often the most practical position may be sitting (on the operating room table), in that this will prevent the larynx from falling posteriorly as it does in the supine position.

Nasotracheal intubation, blind and unblinded, is illustrated in the video below.

Establish the patency of the nares with a well-lubricated nasal trumpet (see the images below). Placement of a nasal airway to dilate the nasal cavity before nasotracheal intubation may facilitate subsequent passage of the tube.[10, 11]

Inserting nasal trumpet. Note that insertion angle is almost perpendicular to face.

Nasal trumpet insertion (continued).

Insert a well-lubricated tube with fully deflated cuff via a patent, lubricated naris, at a right angle to the face (see the image below).

Direct laryngoscopy with Miller blade. Insert nasal RAE endotracheal tube, and advance it a little before putting laryngoscope in mouth.

Some resistance is commonly encountered, most likely caused by the right arytenoid. This is usually overcome with slight counterclockwise rotation of the tube.

Once the tube is beyond the nasopharynx, introduce the laryngoscope into the oral cavity, and advance the tube under direct vision (see the images below).

Once vocal cords are seen, endotracheal tube is advanced by laryngoscopist or assistant.

Sometimes, to avoid tearing the cuff with the forceps, Magill forceps are needed to guide the tube through the vocal cords; if this is the case, an assistant advances the tube (see the image below).

Endotracheal tube is advanced with Magill forceps by laryngoscopist. Assistant helps advance tube by slowly pushing it in.

Magill forceps directing endotracheal tube (above cuff) for its advance through vocal cords.

A randomized comparison by Yeom et al found that in using the GlideScope device, a vascular forceps with a tube exchanger offered advantages over a Magill forceps—specifically, reduced total intubation time and lower incidence of epistaxis.[12]

A randomized controlled clinical trial by King et al found that the use of video laryngoscopy for routine nasotracheal intubation in oral and maxillofacial surgery procedures, compared with direct laryngoscopy, was associated with significantly faster intubation times and decreased use of Magill forceps.[13]

Complications of nasotracheal intubation include the following:

• Epistaxis (the most common complication), resulting from abrasion of the nasal mucosa when the tube is passed posteriorly
• Damage to nasal cavity (avulsion of nasal polyps, fracture of the turbinates, septal abscesses)
• Aspiration
• Vagal stimulation
• Laryngospasm
• Vocal cord damage ^[14]
• Bacteremia from introduction of nasal flora to the trachea
• Pneumothorax

If bleeding is noticed but intubation could still be achieved, the procedure should be completed. An endotracheal tube in proper position allows tamponade of the bleeding and protects the airway. If repeated attempts are needed, the tube should be withdrawn until the cuff is positioned to be inflated in order to tamponade the bleeding (usually in the postnasal space); another option is to withdraw the tube completely and pinch the nostrils together. Preprocedural xylometazoline spray may be considered as a preventive measure.[15]