When the mouth is off limits, nasal intubation can be a valuable technique for gaining an emergency airway.
With or without fiberoptic assistance, nasal intubation remains a valuable technique in some emergency airway situations, despite its overall decline in use. It is best in patients who are not critically hypoxic and in whom there is obvious oral pathology making intubation and ventilation through the mouth problematic. In these situations, when the mouth is off limits, awake intubation must occur through the nose or through the neck. Examples include severe angioedema of the tongue, and mechanical obstructions to mouth opening from mandibular fixation or other oral pathology. I have also used the technique in patients with fixed neck contracture and limited mouth opening. In situations of intrinsic laryngo-tracheal pathology (i.e., tumor etc.) nasal intubation should only be done with fiberoptic assistance.
The procedure is relatively contraindicated in patients who are coagulopathic because of the risk of hemorrhage, and more difficult with poor air excursion (asthma, COPD, etc.). If there is evident disruption of the midface, nasopharynx or roof of the mouth, the nasal route should not be used.
Overview of Nasal Intubation Technique
The author’s recommended technique is as follows:
1) Anesthetic spray into nare (5-10cc of 4% topical lidocaine with oxymetazoline or neosynephrine, either via disposable single patient bottle or via disposable spray pump atomizer or syringe.
2) Insert nasal trumpet lubricated with 2% lidocaine jelly.
3) Spray anesthetic spray through trumpet and remove trumpet.
4) Insert “trigger” tracheal tube 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.
5) Spray anesthetic once through tube again. The patient will cough and buck.
6) Pass tracheal tube through cords during inhalation.
7) Confirm placement, sedate, and administer muscle relaxants as needed.
The overall sequence is STSTS: Spray, Trumpet, Spray, Tube, Spray.
Topicalization and Pharmacologic Adjuncts
Although topical cocaine works effectively as a vasoconstrictor and topical anesthetic, equally effective is a combination of 4% topical lidocaine (liquid solution), and oxymetazoline or phenylephrine. Oxymetazoline (Afrin) or phenylephrine (Neosynephrine) come in small plastic squeeze bottles that are appropriate for single patient use. The lidocaine solution (5-10cc of 4%) can be added to the spray bottle by either taking off the cap or by injecting the solution through the spray-tip hole with a narrow gauge needle. Excessive use of 10% lidocaine spray has been associated with lidocaine toxicity and emesis. The 10% spray is no longer available in the U.S. A recent study found that up to toxic levels of lidocaine did not occur even when using up to 30 or 40 cc of 4% lidocaine, but this was in obese patients, and these volumes are not needed. In the author’s experience, 10 cc of 4%, or 20 cc of 2% is more than adequate. Wolfe-Tory Medical (Salt Lake City, UT) makes a spray pump disposable atomizer as well as bendable spray tubes and syringes useful for anesthetizing the posterior pharynx [see image 4]. An alternative means of anesthetizing the mouth, larynx and trachea is with an acorn nebulizer, using 2% or 4% lidocaine.
Proper topicalization is essential not only for patient comfort, but also to ensure proper placement. Without proper topicalization, the patient will gag, cough, and swallow the tube, preventing it from going into the trachea.
Conscious sedation for intubation, using a combination of fentanyl and midazolam, may be appropriate and improve patient comfort, depending on the situation. In the patient who is too agitated to permit the procedure, small aliquots of ketamine (10 mg IV, repeated up to 40-50 mg total, although more can be given if needed) with midazolam works magically well to facilitate the procedure.
To minimize the risk of hypoxia, deliver oxygen using a nasal canula through the contralateral nare or through the mouth.
Inserting the Nasal Trumpet
The bevel on the nasal trumpet should be oriented facing the turbinates (laterally), so that the leading edge moves along the septum and does not bang into the turbinates. The septum is medial and the turbinates lateral. A trumpet inserted on the left side can follow its curvature into the nose (curvature facing downward), while insertion on the right should begin with the trumpet curvature upside down (curvature initially facing upward). The floor of the nasopharynx is straight backwards (i.e., 90 degrees in relation to the face, not upward) [see Figure 1]. The trumpet adds additional anesthesia to the posterior pharynx and hypopharynx, is much softer than the tracheal tube, and demonstrates a patent path toward the larynx. If the trumpet does not pass easily, the other side should be used. A slight pressure, keeping the leading edge of the trumpet downward and toward the septum, is the best way to complete placement. Using trumpets of increasing diameter does not dilate the nostril and only serves to increase bleeding. The trumpet should be fully advanced and kept in place for one minute.
This regimen of nasal spray and rubber trumpet will not anesthetize the larynx, so repeat spraying of the anesthetic solution through the trumpet is recommended. This will cause the patient to buck and cough, which in turn spreads the anesthetic above and below the vocal cords. After the solution has been sprayed through the trumpet it can be removed.
Nasal Tube Insertion and Passage
The tracheal tube (as large as will be tolerated, ideally at least a 7mm ID), lubricated with a small amount of water soluble jelly, should be placed into the nostril like the trumpet, in a manner that prevents the leading edge from banging into the turbinates. Lubrication of the tracheal tube itself should not use lidocaine jelly, as there have been FDA warnings of it drying and causing tracheal tube obstruction. When the tracheal tube is inserted into the nostril, with the curvature of the tube pointing downward, the bevel on a standard tube faces towards the left. Accordingly, tube insertion into the left nostril of the patient follows the curvature of the tube, and the leading edge of the tube will correctly pass alongside the septum. If the right nostril is used, the initial insertion of the tube should be with the curvature upside down (curvature facing upward), until the nasopharynx is passed (approximately 3–4 inches), at which point the tube can be rotated back with its curvature in the standard direction. The path of a nasally placed tracheal tube must make two anterior deflections, first turning down from the nasopharynx, and second coming off of the posterior pharynx into the larynx. Because of these deflections, the author prefers to use a trigger tube, or directional-tip tube (manufactured under brand names “Endotrol” by Nellcor, Pleasanton CA and also “Easycurve Articulating” tube by Parker Medical, Englewood CO) [see Figure 3]. The Parker has a second advantage over other tubes in addition to its softer durometer and trigger; the ski-tip symmetric bevel of the tube minimizes trauma to the nasal turbinates and allows simpler insertion into the nasopharynx.
Another useful adjunct for nasal intubation is a Beck Airflow Airway Monitor (BAAM) (Great Plains Ballistics, Lubbock, TX), attached to the base of the tracheal tube [see Figure 5]. This small plastic whistle accentuates the noise of the air movement through the tube. One must be careful, however, that the BAAM whistle is not attached too firmly to the 15 mm connector of the tracheal tube, because it will need to be disconnected after tube passage.
If after trumpet placement and withdrawal the tracheal tube does not easily make the bend from the nasopharynx into the pharynx, gentle steady pressure should be applied, directed slightly medially (staying on the septum), with the proximal portion of the tube held upright (making sure the tip is heading along the floor of the nasopharynx, perpendicular to the face). As the tube is farther advanced toward the larynx, the back end of the tracheal tube should be oriented toward the patient’s contralateral nipple. This helps direct the tip toward the midline, otherwise the tube tip will lodge in the ipsilateral piriform recess [see Figure 2].
At approximately 14–16 centimeters depth, which is evident by tracheal tube markings, there should be loud air movement through the tube. Anesthetic solution through the tube at this point adds additional laryngeal anesthesia and elicits coughing. When the patient inhales, passage through the vocal cords and into the larynx is done swiftly. Successful tracheal passage will induce laryngeal reflexes (coughing), loss of phonation, and air movement through the tube. If not already done, it may be necessary to restrain the patient’s arms because passage of the tube may elicit arm movement, head turning, and other efforts to remove the tube. The tube should be carefully held in place and then secured with tape, with the tube markings at 26 cm at the nostril for women and 28 cm for men.
If the tube repeatedly enters the esophagus, adjustment of head positioning, tube twisting, or laryngeal manipulation may assist in directing the tube forward into the trachea.
The best means of directing the tube tip forward into the trachea is to perform the procedure with a trigger tube at the outset. Gentle traction on the plastic trigger will direct the tip anteriorly. Use of this tube markedly improves the first pass success rate of nasal intubation. Pulling the trigger should be done gently. Excessive force will impede advancement and cause the tube tip to go into the vallecula or to catch on the tracheal rings.
Dr. Levitan teaches emergency medicine at Jefferson Medical College and at the Univ. of Maryland and helps run a monthly airway management course involving specially prepared cadavers: jeffline.jefferson.edu/jeffcme/Airway