Nasotracheal Intubation – Indications, Contraindications

Nasotracheal intubation (NTI) involves passing an endotracheal tube through the naris into the nasopharynx and the trachea; most commonly after induction of general anesthesia in the operating room. The use of NTI permits the administration of anesthetic gases without obfuscation of intraoral anatomy and is commonly used for procedures including dental, oropharyngeal, and maxillofacial operations. [rx][rx][rx]NTI am an essential skill for anesthesia providers.  Due to the potential complications in performing NTI, it is recommended that NTI not be attempted by anyone who is not skilled at orotracheal intubation as well.[rx][rx]

Anatomy and Physiology

Being able to perform NTI properly requires knowledge of the anatomy of the nasal vestibule, nasopharynx, oropharynx, and hypopharynx.

The nasal cavity begins at the anterior nares and ends at the posterior end of the nasal septum where it channels into the nasopharynx via the posterior nasal apertures (choanae). The nasal cavity sits above the oral cavity and hard palate and rests below the skull base.

The hard palate provides the base of the cavity that runs horizontally and directly behind the anterior nares. The ceiling of the nasal cavity is formed from the narrow cribriform plate of the ethmoid bone. Lastly, both left and right lateral walls are established by the medial wall of the respected orbit superiorly and the maxillary sinus inferiorly.

The lateral nasal walls incorporate three structures, the turbinates, which project into the nasal passages as ridges of tissue and are responsible for maintaining moisture and warmth in the nasal cavity as air flows through.

The inferior turbinate is the largest of the 3 and projects along the complete lateral nasal wall. The inferior turbinates are often responsible for blocking nasal airflow when they are enlarged or inflamed. The middle turbinate projects into the central nasal cavity adjacent to the nasal septum. Finally, the superior turbinate, the smallest of the three, attaches to the skull base superiorly and the nasal wall laterally.

The nasal cavity is separated by a nasal septum consisting of both a cartilaginous part that sits anteriorly and a bony portion that rests more posteriorly. This septum separates the anterior nasal pathway into a left and a right side, where these 2 cavities eventually coalesce to form a single continuous cavity in the back of the nose (the nasopharynx).

The nasal cavity is lined by respiratory mucosa (histologically described as ciliated pseudostratified columnar epithelium) lying on an extremely vascular stroma. These cells produce serous secretions that aid in humidification of inspired air. The cilia help to trap unwanted debris from entering the lungs.

Due to the high vascularity of the nasal cavity, minor trauma to any part of the tissue can cause bleeding to occur (epistaxis). The anterior nasal septum is particularly susceptible to developing epistaxis owing to the superficial location of the arterial plexus. This plexus is known as Kiesselbach’s area and is supplied by branches of the anterior and posterior ethmoid, superior labial, sphenopalatine and greater palatine arteries.

While considering normal nasal cavity anatomy, it is also important to understand that anomalies do often exist. Septal deviation is perhaps the most common anomaly which usually involves the cartilaginous aspect of the nasal septum. The deviation is most often due to trauma but can also be caused by continuous nasal congestion from recurrent sinus infections. Other variations to normal anatomy include conditions that result in unilateral obstruction such as nasal polyps, concha bullosa, and spurs. It is important to consider these anomalies during pre-anesthetic evaluation to minimize any complications as most of these variations will result in changes to airflow dynamics inside the nasal cavity. Nasal polyps or spurs may be unilateral which may dictate which side of the nose is more amenable to NTI.[rx][rx][rx]

Indications of Nasotracheal Intubation

Indications for NTI include, but are not limited to the following:

• Intraoral and oropharyngeal surgery
• Complex intra-oral procedures involving mandibular reconstructive procedures
• Rigid laryngoscopy
• Dental surgery
• Maxillofacial or orthognathic surgery
• Intraoral and oropharyngeal surgery.
• Oral route of intubation not possible due to trismus
• In ICU as an alternative to tracheostomy for longer ventilation periods
• Surgery of maxillofacial cases needing better surgical access
• Tonsillectomies
• Rigid laryngoscopy and microlaryngeal surgery

Contraindications of Nasotracheal Intubation

Absolute contraindications include:

• Suspected epiglottis
• Midface instability
• Previous history of old or recent skull base fractures
• Any known bleeding disorder that could predispose the patient to severe epistaxis
• Choanal atresia
• Patients that have experienced high-speed trauma or isolated facial trauma may have undiagnosed skull fractures that may result in nasotracheal tube placement into the brain.  It is best to avoid NTI in these patients.

Relative contraindications include:

• Anything that could compromise the nasal air passage (large nasal polyps, foreign bodies)
• Recent nasal surgery
• History of frequent episodes of epistaxis

METHOD

Blind nasal intubation as described by Rich Levitan: ‘Spray-Trumpet-Spray-Tube-Spray’

• Anaesthetic spray into naris (5-10cc of 4% topical lidocaine with oxymetazoline, either via disposable single patient bottle or via disposable spray pump atomizer or syringe)
• Insert nasal trumpet lubricated with 2% lidocaine jelly (leave in place for 1 min)
• Spray anesthetic spray through trumpet and remove trumpet
• Insert “trigger” tracheal tube (as large as will be tolerated, at least 7.0) to approximately 14–16 cm, keeping the proximal end of the tube directed toward the patient’s contralateral nipple (this helps to direct the tip of the tube toward the midline). There should be loud breath sounds audible through the tube. This verifies location above the laryngeal inlet.
• Spray anesthetic once through tube again. The patient will cough and buck
• Pass tracheal tube through cords during inhalation
• Confirm placement, sedate, and administer muscle relaxants as needed

OTHER INFORMATION

• deliver oxygen using a nasal cannula through the contralateral naris or through the mouth
• In the patient who is too agitated to permit the procedure consider using small aliquots of ketamine (10 mg IV, repeated up to 40-50 mg total, although more can be given if needed)
• when passing a nasal trumpet or ETT ensure the bevel faces the turbinates (laterally) and that the tube is advanced along the septum (medially) and the floor of the nasal cavity (which is perpendicular to the plane of the face)
• adjustment of head positioning, tube twisting, or laryngeal manipulation may assist in directing the tube forward into the trachea
• patient may need restraint once he ETT passes the cords
• typically 26cm at the nose for women and 28cm at the nose for men

Equipment of Nasotracheal Intubation

Some of the necessary equipment needed to perform a nasotracheal intubation includes the following:

• Endotracheal tube (Nasal RAE or standard endotracheal tube)
• Lidocaine jelly or a water-soluble lubricant
• Magill forceps
• Laryngoscope
• Vasoconstricting nasal spray (oxymetazoline 0.05% or phenylephrine nose drops 0.25% to 1%)
• Syringe to inflate cuff

Preparation of Nasotracheal Intubation

A pre-anesthetic evaluation must be performed for each patient undergoing a procedure requiring anesthesia with a particular focus on identifying any potential risks or complications related to the upcoming procedure and composing an individualized plan for patient care. Often, the patient can relay important information regarding unilateral restriction or congestion and give some direction as to which side should be used for the NTI. If the patient interview does not yield information related to relative patency of one side versus the other, then either side of the nose may be used.

An anterior rhinoscopy may be performed (this is not a common practice) which gives the provider the ability to visualize the anterior portion of each nasal cavity. The main limitation of anterior rhinoscopy is the inability to provide any information regarding the posterior nasal cavity. To fully assess the pathway, a flexible fiber-optic bronchoscope may be passed into the nasopharynx.[rx][rx]

Preparation for insertion of an NPA involves 2 steps. First, the healthcare provider gets the correct size NPA, and second, the provider coats the NPA with lubricant, anesthetic jelly, or any water-soluble lubricant.

In the ideal setting preparation for NT intubation can include all of the below-mentioned steps, but if the procedure if needed to be done immediately, the healthcare provider may be unable to prepare anything and may have to blindly place the NT tube when that is the indicated route of securing the airway.

Preparatory steps, not necessarily in the below order, include:

• Positioning the patient in the sniffing position, attaching the patient to the monitor, pulse oximetry, blood pressure monitor and cardiac monitor. If available, set up end-tidal carbon dioxide monitor (capnography)
• Placing 2 peripheral intravenous (IV) accesses and starting 1 liter of crystalloid fluid (if the patient is not fluid overloaded or at risk of overload)
• Preoxygenation via nasal cannula, non-rebreather, BVM, BIPAP increases the oxygen reserve and the time to desaturation after a sedative and/or paralytic medications have been given.
• Having a BVM ready bedside
• Turning on wall suction, setting up the suction tubing and a yanker
• Having a respiratory therapist or other personnel prepared with a ventilator
• Preparing sedative and paralytic medications if plan on sedating and/or paralyzing
• Having a CO2 detector, EtCO2
• Setting up the backup airway
• Setting aside 6 to 7.5 cm NT tubes and checking the cuff of the tubes for an air leak
• If using flexible bronchoscopy, having the bronchoscope turned on and placed bedside
• Placing the NT tube in warm sterile saline to allow the tube to soften and allow for a smoother insertion; this can decrease the risk for trauma to the nasal passageways.
• Assessing for the more patent nostril, which can be done by asking the patient to hold one nostril and take in a deep breath, identifying which naris allows for more air movement. It can also be assessed by placing an NPA and judging which naris allows for easier insertion. If the provider will be utilizing a flexible bronchoscopy, then the scope can be used to visualize which nostril is more patent.
• Lubricating the tube and bronchoscope with lubricant or lidocaine jelly/ointment. Care should be used to avoid smudging the camera of the bronchoscope.
• Spraying a topical vasoconstrictor in bilateral nares to reduce bleeding risk
• Placing an NPA coated with lidocaine jelly/ointment to provide anesthesia and lubrication
•  Spraying aerosolized lidocaine in the oropharynx
• Performing serial dilations of the bilateral nares or more patent nares with increasing larger diameter NPAs coated with lidocaine or lubricant

Nasal Intubation Techniques

Once beyond the nasal cavity, there are various techniques available to advance the ETT into the trachea.

• The method of picking up ETT and catheters in the oropharynx with the help of a forceps and guiding them into the trachea under direct vision by laryngoscopy was first described by Magill in 1920[rx]
• Various aids to blind nasal intubation have been employed including:

  1. Listening to breath sounds directly through the ETT or using an extension tube and earpiece[rx]

  2. Inflating the tracheal cuff (the cuff of the ETT is inflated in the oropharynx to help guide the tip of the tube into the trachea)[rx,rx]

  3. Monitoring the end-tidal carbon dioxide levels[rx]

  4. The technique of gently identifying the right pyriform fossa. With the tip of the ETT, the right pyriform fossa is identified as a bulge in the skin. Pulling the ETT back slightly and rotating it counterclockwise through 90° and then advancing toward the midline give access to the trachea. Depending on the curvature of the ETT, a minor adjustment in the degree of the atlantooccipital joint extension has to be made. Sometimes, the tube is abutting the anterior commissure, in such conditions flexion of the head helps. If the tube enters the esophagus, withdrawing the tube and reinserting it with head in hyperextended state achieves intubation

• Stylet-facilitated nasotracheal intubation. In this technique, the curved stylet is used to flex the tip of the ETT anteriorly and is removed immediately once the tube is in the nasal cavity. This helps in the smoother insertion of the tube through the nasal cavity, and the chances of bleeding are minimal
• With the use of a light wand The more commonly used technique describes the use of a light wand alone. After adequately preparing the patient with topical anesthesia, the patient is counseled and prepared psychologically. An appropriate-sized ETT is inserted till it is in the oral cavity (appreciated by a loss of resistance). The theater lighting is dimmed, and the light wand is inserted in the ETT till the fixer touches the top of the ETT
• Technique of using the Endotrol ETT and a light wand – This is a different method that uses the Trachlight and Endotrol tube (Mallinckrodt, Athlone, Ireland). The inner metal stylet is removed from the Trachlight, and the light wand is placed in the Endotrol tube till the tip of the light wand and the tip of the ETT are aligned. The Endotrol tube has a wire hook with which the curve of the tube can be controlled
• A modified nasal trumpet (MNT) to facilitate fiber-optic intubation – The MNT is a functionally similar device to both the laryngeal mask airway (LMA)[rx] and the cuffed oropharyngeal airway (COPA).[rx] The MNT establishes a patent airway and may substitute for mask ventilation in the unintubated patient. It permits positive pressure ventilation. It is placed blindly. Evidence suggests that when used as a tool for facilitating intubation, MNT is most likely more efficient and safer as compared to both the LMA and the COPA. The MNT may be inserted in a spontaneously breathing patient, who can either be awake or anesthetized. The MNT permits fiber-optic intubation, both oral and nasal, while it is in place
• Nasotracheal intubation with the Bonfils retromolar fiberscope. The Bonfils retromolar fiberscope usually referred to as the “Bonfils,” is one of the devices developed for managing the difficult airway.[rx] It was initially used for the management of patients with an anticipated difficult airway around the 1990s and as of today, it continues to be a very useful device for the management of the unexpected difficult airway[rx,rx,rx]
• With the patient under general anesthesia and under the appropriate level of anesthesia, relaxed as for any intubation procedure, the tube is introduced into the selected and prepared nasal cavity; the ETT is advanced till it reaches the oropharynx. Then, an assistant is required to perform upward mandibular traction, and the Bonfils retromolar fiberscope is inserted from the right lip commissure and a “retromolar gonioscopy” is performed. The Bonfils is advanced until the epiglottis and the vocal cords are identified. Then, the Bonfils is slightly withdrawn, and a panoramic view of the oropharynx is sought and the tracheal tube is identified. The person doing the intubation maneuvers the Bonfils and the ETT, and a skilled and trained person maintains the upward mandibular traction, which helps improve the visibility of the vocal cords. The tube is advanced up to the field of observation of the Bonfils and immediately the tube is guided up to the trachea under direct vision with the Bonfils
• Fiber-optic nasal intubation – The frequency of difficult intubation due to the inability of passing an ETT over an orally inserted fiberscope varies between studies, ranging from 0% to 90%.[rx] Fiber-optic intubation when performed nasally can be as difficult as oral fiber-optic intubation. The primary cause of the difficulty, while the ETT is being advanced over the fiber-optic bronchoscope, is considered to be due to the deviation in the course of the ETT from that of the fiberscope. This is because of a gap present between the two. The ETT usually deviates toward the epiglottis, arytenoids cartilage, pyriform fossa, or esophagus.[rx,rx] Showed that the sites of impingement of the ETT during fiber-optic nasal intubation are usually the posterior structures of the laryngeal inlet and suggested rotating the tube counterclockwise as a solution[rx]
• Single-hand maneuver for flexible fiber-optic bronchoscope-guided nasotracheal intubation (FNI)[rx] The single-hand maneuver is applied to maintain airway patency during the process of performing FNI in anesthetized patients. The little finger is placed below the angle of the mandible; the ring finger is placed below the body of the mandible, and the middle finger under the mentum. With the fingers in this position, manipulation of the degree of chin lift can be adjusted according to the quality of the bronchoscopic view. The bronchoscope is held by the thumb and index finger of the same hand
• Nasal intubation in the sitting position sitting endotracheal intubation has been proven to be more successful when compared to conventional intubation[rx]
• Using a dual bougie for nasotracheal intubation[rx] When it is anticipated that the nasotracheal intubation would be difficult, but at the same time conventional orotracheal intubation could be done through conventional laryngoscopy, this technique is used. A cuffed tracheal tube is placed into the trachea. The position of the tube is confirmed as usual through auscultation and capnography. This is followed by inserting an appropriate size cuffed tracheal tube nasally which is then guided into the oropharynx. An Eschmann bougie is passed through this nasal tube to the glottic aperture guided with the aid of a Magill forceps by direct laryngoscopy

Complications

The most common complication of nasotracheal intubation is epistaxis, which occurs with nearly every NTI. Other complications include bacteremia (by introducing bacteria from the nasal cavity into the body due to trauma from the tube) and risk of perforation (retropharyngeal perforation or perforation of a piriform fossa). As mentioned previously, it is best to avoid NTI in patients who have sustained high-speed trauma or isolated facial trauma due to the risk of inadvertent placement of the ETT into the brain.

• Septal hematoma
• Septal abscess
• Avascular necrosis of nasal septal cartilage leading to saddle deformity
• Nasal obstruction
• Blowout fractures: Extraocular muscle entrapment and diplopia
• Nasolacrimal duct injury: Due to the close relationship of the duct to the nasal bones
• Fracture of cribriform plate and cerebrospinal fluid (CSF) rhinorrhoea
• Inability to reduce: Fractures that cannot be reduced by closed techniques are candidates for open reduction.[rx]
• Airway compromise and hemorrhage.[rx]
• Nasofrontal duct and or lacrimal duct disruption as a result of direct damage or due to displaced fracture segments.[rx]
• Facial deformity, as full correction of telecanthus or nasal depression can be difficult to achieve, and some patients will retain a degree of asymmetry. Depending on the surgical approach, patients may experience temporary or permanent paralysis and or anesthesia of the forehead. Scars that cannot be hidden in the hairy scalp or skin folds may be prominent.[rx]
• Infection of the incision site, soft tissues, and meninges are recognized complications from these injuries.[rx]
• Mucocele formation is a complication of sinus or lacrimal drainage disruption and can become infected.[rx]
• Mental health, as patients with facial injuries are at greater risk of developing post-traumatic stress disorder or anxiety-related disorders. Particularly those who were victims of assault.[rx]

References