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Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018
| Contributor Information
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Image from Plataki M, Tzortzaki E, Lambiri I, Giannikaki E, Ernst A, Siafakas NM. BMC Pulm Med. 2006;6:7. [Open access.] PMID: 16603056, PMCID: PMC1464140.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
The fiberoptic bronchoscopy image reveals a more than 70% circumferential tracheal stenosis 1-2 cm beneath the vocal cords and marked tracheal mucosal inflammation.
Fiberoptic intubation (FOI) is the gold standard for difficult airway management.[1,2] Although FOI can be undertaken with the patient awake or asleep, if a concern exists about obtaining an airway, it is best performed with the patient awake to preserve the patient's respiratory drive and to maintain spontaneous ventilation.[1,3,4] Awake FOI (AFOI) can be achieved via a nasal or oral approach by numbing the airway and sedating the patient,[2,3] unless the patient is obtunded and will tolerate it without any medications. The oral approach is the most common, because this route is shorter, larger endotracheal tubes (ETTs) can be used, and it avoids epistaxis.[5]
Indications for AFOI include, but are not limited to, the following[2,6]:
A known or anticipated difficult airway
Limited neck mobility, such as due to a cervical spine injury or arthritis
Anatomic distortion from trauma, radiation, a mass, previous surgery, or other causes
Top image from Wikipedia / bigomar2; bottom image courtesy of Medscape.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Nasal Approach
The nasal approach provides a straighter line of access to the larynx than the oral approach, and it is usually better tolerated by patients.[3,6] This route is often used if the patient has a limited mouth opening or their jaw will be wired after surgery, or when an oral tube will be in the surgeon's way.
The ETT size should be 0.5 to 1.0 mm smaller than that used for an oral approach in the same patient,[7] but take care to ensure the tube is long enough. Generally, a regular ETT (top image) is used rather than a nasal Ring-Adair-Elwyn (RAE) tube (bottom image, north-facing RAE tube), owing to difficulty loading and advancing the nasal RAE tube with the fiberoptic bronchoscope placed through it.
For an average or large male, use a 7.5-mm ETT; in a smaller male, use a 7.0-mm ETT, and in a woman, use one size smaller (6.5 or 6.0 mm).[7,8] A nasopharyngeal airway (trumpet) can aid dilation of the nasal passage, and its size can help to guide the ETT size.
Top left: Adapted image from Wikimedia Commons / FirstAdmiral. Top right and bottom: Images courtesy of Medscape.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
The nasal cavity is innervated by branches of the trigeminal nerve (top right image), and it also has a very rich vascular supply (top left image).[9] Therefore, these regions require anesthesization and vasoconstriction. Cocaine-soaked pledgets can be used to both numb the nerves and vasoconstrict the blood vessels; phenylephrine spray or cotton-soaked applicators can be applied inside the nostrils for vasoconstriction.[2,4]
Prepare the nose with a 5% or 10% cocaine solution or phenylephrine spray/cotton applicators to vasoconstrict the nasal passage and prevent bleeding when advancing the ETT.[4] Apply an anesthetic (eg, lidocaine ointment) on the nasal trumpet (bottom image) to lubricate and numb the nasal passage.[6,7]
Image courtesy of Medscape.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Oral Approach
Different oral intubation airways exist to help guide the fiberoptic bronchoscope, such as the Berman, Ovassapian (shown, superior view), and Williams airways.[3] These airways not only help to move the tongue out of the way, but they also help correctly position the scope in the posterior pharynx for guidance through the vocal cords.
The oral route can be more difficult than the nasal route, because this approach requires the scope to make a sharp turn in the posterior oropharynx before it can enter the hypopharynx—unlike the nasal approach, which has a more direct path to the airway and is not obstructed by the tongue.[3] However, as noted earlier, the oral route is usually preferred due to complications associated with nasal intubations (eg, epistaxis, false passages, sinusitis with prolonged intubations) and the need to place a smaller ETT with a nasal approach,[5] which can be an issue in patients with poor respiratory function or those who need to remain intubated.
Images courtesy of Medscape (left) and Alma Juels, MD (right).
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Lubricate the inside of the appropriate-size ETT (eg, with a topical anesthetic such as Cetacaine [benzocaine, aminobenzoate, tetracaine]) for ease of its advancement over the fiberoptic bronchoscope (left image). Placing a piece of tape at the end of the upper ETT helps to keep it in place on the scope while the scope is navigated to the carina. Lubricating the exterior of the ETT aids in advancing it into the trachea. Anesthetize the airway with a 2% or 4% lidocaine solution, lidocaine cream, or a topical local anesthetic (right image).
To optimize the view with the fiberoptic scope, clear/reduce airway secretions with an antisialogogue such as glycopyrrolate.[2,6] (Administer glycopyrrolate early, as its onset of action takes about 20 min.) Also consider the use of metoclopramide (Reglan) to help with gastric emptying, and citric acid/sodium citrate (Bicitra) to neutralize stomach acids.
Images from James Heilman, MD (left), Psychonaught (center), and John Oyston (right), all via Wikimedia Commons.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Sedation
Although several medications can be used to sedate patients for AFOI, patients' airways also must be maintained. Key concerns with any sedation are to not remove the respiratory drive and to not oversedate. Patients need enough sedation to maintain spontaneous respiration and be cooperative.
Typically, boluses of midazolam, fentanyl, or ketamine can be given, or infusions of propofol, dexmedetomidine, or remifentanyl can be used.[4] Titrate the selected agent to the desired effect. Ketamine[3] and dexmedetomidine[3,4] are good choices because they do not alter the respiratory drive.
Adapted image from Cancer Research UK via Wikimedia Commons.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Numbing the Airway
To perform AFOI, anesthetization to control the gag and cough reflexes is required in the following areas:
Nasal intubation: The nasopharynx, oropharynx, hypopharynx, larynx, and trachea
Oral intubation: The oropharynx, hypopharynx, larynx, and trachea
Methods to numb the airway include the use of the following:
Atomizers or nebulizers [2-4]
Direct injection[2-4]
"Lollipop": Lidocaine ointment (5%) is placed on the end of a tongue blade with gauze; the patient sucks on this while it is advanced as tolerated[10]
Injecting 2% or 4% lidocaine through the side port of the fiberoptic bronchoscope[10]
Images courtesy of Medscape. A = artery; N = nerve.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
The sensory innervation of the airway is divided into three regions, as follows[2,4,6]:
The nasal cavity is primarily innervated by the trigeminal nerve.
The base of the tongue and oropharynx is innervated by the glossopharyngeal nerve.
The hypopharynx, larynx, and trachea are innervated by branches of the vagus nerve.
The gag reflex is controlled by branches of the glossopharyngeal and vagus nerves, whereas the cough reflex is mediated by the vagus nerve.[11] Glottis closure is controlled by branches of the vagus nerve (superior laryngeal [above the vocal cords]; recurrent laryngeal nerves [below the vocal cords]).[11]
Images from Fuehner T, Fuge J, Jungen M, et al. PLoS One. 2016;11(3):e0150905 [Open access.] PMID: 26978775, PMCID: PMC4792394.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Two types of atomizer devices and their implementation are shown.
Numbing the oropharynx
The following techniques may be used to anesthetize the oropharynx[2,6]:
Viscous lidocaine gargle (swish and spit out)
Nebulization with 3-5 mL of 4% lidocaine or tetracaine
Atomization with 4% lidocaine
"Lollipop" (lidocaine ointment)
Oral airway with lidocaine ointment/cream
Glossopharyngeal nerve block
Adapted image from Wikimedia Commons / BruceBlaus.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
The sites for the anterior tonsillar pillar method of glossopharyngeal nerve block is shown.
Glossopharyngeal nerve block
The glossopharyngeal nerve can be blocked by placing swabs soaked in a local anesthetic, or injecting 1% or 2% lidocaine, at the posterior tonsillar pillar (not shown). This is not a popular technique as the patient may bite down.
Alternatively, 1% or 2% lidocaine injection at the site of the anterior tonsillar pillars (yellow "x"s), a viscous lidocaine gargle (for 45-60 sec), or a lidocaine "lollipop" (patients suck for 3-5 min) may be used.
Image courtesy of Medscape.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Numbing the posterior pharynx
A technique to anesthetize the posterior pharynx from the base of the tongue to slightly above the vocal cords is blocking the superior laryngeal nerve.[2,6] This can be achieved by using a 25- or 27-gauge needle to inject 1.5 mL of 1% or 2% lidocaine on each side of the hyoid bone at the greater horns. (Palpate the sides of the hyoid bone; at the very tip bilaterally is where the greater horn and superior laryngeal nerve can be found.[2,4])
Alternatively, 5-mL atomization or nebulization of 4% lidocaine can be used.[4,12] Although this type of nerve blockade is noninvasive, it often results in inadequate anesthetization.[2]
Image courtesy of Medscape.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Numbing the area below the vocal cords
There are a few ways to block the recurrent laryngeal nerve, which innervates the area below the vocal cords as well as part of the cough reflex.[2] The most reliable method is transtracheal injection of 5 mL of 4% lidocaine through the cricothyroid membrane. Locate the cricothryoid membrane in the middle of the neck, and insert a 22- or 25-gauge needle through the skin and membrane, stopping once air is aspirated.[2] Another person should hold the patient's head, and the patient should not cough for as long as possible.
While stabilizing the hand with the syringe on the patient, quickly inject the local anesthetic and remove the needle. The patient will eventually cough, allowing spread of the lidocaine. This technique can be challenging, if not impossible, in a patient with an obese neck, distorted neck anatomy, or an anterior neck mass, because clinicians may be unable to locate the cricothyroid membrane to inject through it.
Nebulization or using direct visualization once past the vocal cords to inject the anesthetic through the side port of the scope is another option.
Image from Wikimedia Commons / melvil.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
The radiograph depicts aspiration pneumonia in a patient.
Concerns About Numbing the Airway
One key concern regarding anesthetization of the airway, both above and below the vocal cords, is that it may remove the patient's protective airway reflexes. Other considerations include whether the patient has been nil per os (NPO), as well as poor visualization of the airway due to the presence of secretions or blood. Aspiration of gastric contents is also a major concern.
Image from Wikimedia Commons / BruceBlaus.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Positioning the Head of the Patient
The optimal patient head position to establish a patent airway for AFOI is not the sniffing position. Instead, it is best to keep the head in a neutral position, and then perform either a chin lift or jaw thrust maneuver, which moves the soft tissues of the upper airway and lifts the epiglottis from the posterior pharyngeal wall, thereby improving the view through the fiberoptic bronchoscope without maneuvering the cervical spine (cervical spine instability may be a concern, particularly in trauma patients).
This positioning of the head also helps to move the tongue out of the way with the use of an oral airway, or another person can pull the tongue outside the mouth if an airway is not in in place. Furthermore, these maneuvers help in advancing the ETT over the scope and passing it through the vocal cords.[6]
Top left image courtesy of Medscape. Top right and bottom left images from Wikimedia Commons / melvil. Bottom right image from Ye D, Shen Z, Zhang Y, Qiu S, Kang C. Trauma Resusc Emerg Med. 2013;21:60. [Open access.] PMID: 23919881, PMCID: PMC3751060.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
Using the Fiberoptic Bronchoscope
When using the fiberoptic bronchoscope, keep it taut between the hands such that the orientation of the tip is the same as that of the control lever. The scope can be moved right or left; to rotate the tip, move the knob up or down.
Using the nasal or oral approach, advance the scope past the open vocal cords (top images).[7] If the cords are closed (bottom left image), wait for the patient to inhale or ask patient to take a deep breath, which will open the vocal cords. Then, navigate the scope all the way to carina, and advance the ETT over the scope and into the trachea.[7] The tracheal rings can be seen below the open vocal cords (bottom right image).
Image from Wikimedia Commons / Welleschik.
Awake Fiberoptic Intubation: Accessing the Airway
Alma Juels, MD | September 7, 2018 | Contributor Information
This image of the normal larynx depicts the vocal cords (1), vestibular fold (2), epiglottis (3), aryepiglottic folds (4), arytenoid cartilage (5), sinus piriformis (6), and base of the tongue (7).
Advancing the ETT
To ease advancement of the ETT, apply a copious amount of lubrication, and consider using a smaller ETT. Various ETTs are available on the market designed to help them advance into the trachea, including those that have a soft, pliable tip (eg, Parker Flex-Tip)[13] or a carinal hook (eg, Shiley)[14] or loop (eg, Parker EasyCurve)[15] to maneuver the tip.
If the ETT encounters resistance when advancing toward the vocal cords, such as becoming stuck in the posterior pharynx or on the arytenoid cartilages above the vocal cords, pull the ETT tip back, rotate it 90°-180° counterclockwise, and advance again.[6]
Airway management is a crucial skill for an emergency practitioner to master. Failure to secure an adequate airway can quickly lead to death or disability. Review our slideshow for best practices.Slideshows, April 2016
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).Procedures, Diseases/Conditions, April 2018
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Contributor Information
Author
Alma Juels, MD
Assistant Professor
University of Colorado Hospital;
Attending Physician
Department of Anesthesiology
Denver Health and Hospital
Denver, CO
Disclosure: Alma Juels, MD, has disclosed no relevant financial relationships.
Editor
Olivia Wong, DO
Section Editor
Medscape Drugs & Diseases
New York, New York
Disclosure: Olivia Wong, DO, has disclosed no relevant financial relationships.
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References
Jarzebowski M, Rajagopal A, Austell B, Moric M, Buvanendran A. Change in management of predicted difficult airways following introduction of video laryngoscopes. World J Anesthesiol. Mar 27, 2018;7(1):1-9. Available at: https://www.wjgnet.com/2218-6182/full/v7/i1/1.htm. Accessed August 24, 2018.
Suresh M, Wali A, Crosby ET. Difficult and failed intubation: strategies, prevention and management of airway-related catastrophes in obstetrical patients. In: Suresh M, Segal S, Preston RL, Fernando R, Mason CL, eds. Shnider and Levinson's Anesthesia for Obstetrics. 5th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2013: ch 24.
Yentis SM, Hirsch NP, Ip JK, eds. Anaesthesia and Intensive Care A-Z E-Book: An Encyclopedia of Principles and Practice. 5th ed. Edinburgh, UK: Churchill Livingstone; 2013: 83, 352.
Jones C. A variety of techniques provide acceptable anesthesia for awake intubation of the airway; ultimately, the most important factors are operator experience and adequate time. In: Marcucci C, Cohen NA, Metro DG, Kirsch JR, eds. Avoiding Common Anesthesia Errors. Philadelphia, PA: Lippincott Williams & Wilkins; 2008: 17.
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