Awake Fiberoptic Intubation

Introduction

• Awake fiberoptic intubation is the gold standard technique for managing a difficult airway in adults.¹
• Awake fiberoptic intubation should be considered in patients with a documented history of a difficult airway or a previous failed intubation.
• Awake fiberoptic should also be considered when the clinical exam is suggestive of a difficult intubation. This includes cases of airway trauma or infection.
• Awake fiberoptic is indicated in adult patients with a known or suspected cervical spine injury or significant cervical spinal disease, where any neck movement can cause possible neurological damage. Fiberoptic intubations require no movement of the neck.
• There is provider-dependent variability in the usage of fiberoptic intubation after a failed traditional intubation attempt.
• Studies have demonstrated that fiberoptic intubation is as fast as the use of video laryngoscopy when performed by experienced anesthesiologists.²

Overview

• Fiberoptic intubation enables direct visualization of the airway through a camera attached to the end of a cable connected to the bronchoscope.
• The camera can be attached to an external screen that can be positioned to allow the operating room team, including the anesthesia provider and surgical team, to see.
• The camera and screen allow for better visualization during intubation.
• Bronchoscopes can be flexible or rigid. The flexible bronchoscope is usually used for awake fiberoptic intubation. It can be used for both oral and nasal intubations.
• Bronchoscopes can also have recording capabilities. These recordings can be used for documentation, teaching, and patient education.
• Bronchoscopes also have a port for suctioning, oxygenation, and administering medications.
• The fiberoptic scope is placed through the endotracheal tube (ETT).

Preparing Patient for Awake Fiberoptic Intubation

Sedation

• Awake fiberoptic intubation can be uncomfortable and anxiety-inducing for patients. It is essential to sedate a patient sufficiently to ensure their comfort.
• It is crucial not to over-sedate the patient. They must be able to spontaneously maintain their airway at all times during intubation. In some cases, the patient cannot be sedated due to the risk of losing the airway. Anxiety may be the only thing keeping the airway patent.
• Commonly used sedative medications include:^1,3
  • Midazolam
  • Fentanyl
    • Low dose, even 25ug, can help blunt the cough/gag reflexes
  • Dexmedetomidine can be administered as a bolus, infusion, or both
  • Ketamine
  • Remifentanil
    • This medication is usually administered as an infusion.
• Glycopyrrolate (0.2 mg IV) should be administered at least 20 minutes prior to intubation. The remaining medications can be administered individually or as a combination at the time of intubation.
• A recent systematic review and meta-analysis of randomized control trials evaluating awake fiberoptic intubation showed no difference in the success rate of fiberoptic intubation between different sedative options. It showed fewer desaturation episodes with dexmedetomidine use. Overall, it demonstrated a high level of safety and efficacy regardless of which sedative was used.³

Anesthetizing the Airway

• Anesthetizing the airway requires blocking the sensory innervation to the nasal cavities (for nasal intubations), oral cavity, pharynx, larynx, and trachea. There are many modalities to achieve sensory innervation blocks, including^1,3
  • Atomizer
  • Nebulizer
  • Direct injection or airway blocks
  • Lollipop:
    • Lidocaine ointment is placed on the end of the tongue blade and covered with gauze. The patient places it in their mouth and sucks on it while advancing the blade, as tolerated, to the posterior pharynx. The lidocaine will melt, and droplets will numb up the posterior pharynx. The patient must be able to suck on the “lollipop.”
  • Injection of lidocaine while advancing the fiberoptic scope:^4,5
    • Lidocaine is injected using the side port of the fiberoptic scope. It can also be injected through an epidural catheter that is placed through the side port and comes out the end of the fiberoptic cable.

Concerns with Numbing the Airway

• Numbing the airway involves taking away a patient’s protective airway reflexes.
• It is important to consider if the patient is appropriately fasted, the presence of secretions and blood in the airway (especially in cases of trauma), and other risk factors for aspiration. Bloody airways are hard to visualize.
• There is always a concern for aspiration when numbing the airway. However, evidence has demonstrated a low risk of aspiration with fiberoptic intubation, even in high-risk patients.⁷

Positioning the Patient

• The sniffing position is not recommended during awake fiberoptic intubation. It is best to have the patient sitting up in a neutral position.
• Chin lift and jaw thrust maneuvers can help move the soft tissue and lift the epiglottis from the posterior pharyngeal wall, thereby improving the view through the fiberscope. This also helps to get the patient’s tongue out of the way, enabling a clear view of the airway. It may be helpful to hold the tongue out.
• Most commonly, this is performed while facing the patient, standing in front of them. Some providers prefer to stand behind the patient while intubating.

Nasal Fiberoptic Intubation^1,6

• The nasal cavity is the most direct path for insertion of an ETT through a fiberoptic bronchoscope. The nasal cavities are inherently space-restricted, usually requiring a smaller tube. Nasal intubations are not the preferred approach for patients who will require prolonged intubation. Some patients, due to airway swelling or distorted anatomy, may require a nasal approach.
• With nasal intubations, there is a risk of epistaxis. The nasal canal is a very vascular region, with Klesselbach’s plexus being susceptible to bleeding.
• Branches of the trigeminal nerve innervate the nasal cavity.
  • The septum is supplied by the anterior ethmoidal nerve (branch of the ophthalmic nerve [V1]).
  • The posterior nasal cavity is supplied by the nasopalatine and greater palatine nerves (branches of the maxillary nerve [V2]).
  • The rest of the nasal cavity is supplied by the greater and lesser maxillary nerves (branches of the maxillary nerve [V2]).
• The nasal passages can be prepared for intubation by administering local vasoconstrictors (such as neosynephrine or historically cocaine), local anesthetics (such as lidocaine or historically cocaine), and dilating the nostrils.
  • Cocaine is an effective vasoconstrictor and local anesthetic but is rarely used in clinical practice.
  • Lidocaine is administered using a soaked pledget or cotton ball, inserted gently into the nasal cavity.
  • Nasal lidocaine atomizer/spray or nasal trumpets with lidocaine ointment can be used for dilation and numbing. Start with smaller nasal trumpets and move up in size until the trumpet is the same size as the ETT.
  • The nasal ETT must be long enough; it is preferable to use a nasal RAE tube, as they are longer.
• The rest of the airway past the nasal cavity is numbed as stated below.

Oral Fiberoptic Intubation^1,6

• It is important to adequately numb the oropharynx to suppress the patient’s gag reflex.
  • The afferent innervation of this reflex is from the glossopharyngeal nerve, while the vagus nerve provides the efferent.
• The glossopharyngeal nerve supplies sensory innervation to most of the oropharynx.

Airway Innervation^1,6

Glossopharyngeal Nerve

• The glossopharyngeal nerve supplies sensation to much of the oropharynx. It also supplies sensory innervation to the vallecula and the base of the tongue (Figure 1).

Vagus Nerve

• The vagus nerve provides innervation from the posterior pharynx to below the vocal cords.
• It provides innervation above the vocal cords through the superior laryngeal nerve and below the vocal cords through the recurrent laryngeal nerve.
• The superior laryngeal nerve controls the gag reflex and sensation from the base of the tongue to just above the vocal cords
• The recurrent laryngeal nerve supplies sensory innervation below the vocal cords.

Topical Approach to Numbing the Airway

• The oropharynx can be numbed using 2% viscous lidocaine. This is distributed by having the patient gargle the solution for 1 minute and then spit it out. Spitting out the lidocaine helps to limit systemic lidocaine toxicity.
• The posterior pharynx and larynx above the vocal cord can be topically anesthetized using a nebulizer or atomizer to deliver 3-5 cc of 4% lidocaine. Lidocaine lollipops are another option for lidocaine delivery. Lidocaine ointment can also be directly applied to the end of an oral airway (e.g., Berman, Ovassapian, or Williams airway). Oral airways provide the additional benefits of protecting the scope, moving the tongue out of the way, and aligning the scope to enter the airway. Finally, 4% Lidocaine can be injected through the side port or an epidural catheter while advancing the fiberoptic past the vocal cords.
• Below the vocal cords, the airway can similarly be topically anesthetized by injecting lidocaine through the side port or through an epidural catheter.^4,5

Direct Nerve Blocks

• The glossopharyngeal nerve can be blocked by holding local anesthetic-soaked swabs or by directly injecting local anesthetic at the anterior tonsillar pillar.
• The superior laryngeal nerve can be blocked by injecting both sides of the greater cornu of the hyoid bone with 2% lidocaine (1.5cc/side with a 25 or 27-gauge needle) (Figure 4).

• The recurrent laryngeal nerve can be blocked by performing a transtracheal lidocaine injection (4% lidocaine 4-5cc) through the cricothyroid membrane (Figure 5). This is performed by inserting the needle tip through the cricothyroid membrane while aspirating, and waiting until air is aspirated before injecting the lidocaine. It can be helpful to have someone hold the patient’s head and instruct them not to cough. The patient should suppress the cough until the needle is removed. Once the needle is out and the patient coughs, it helps spread the local anesthetic, aiding in numbing the area.

• Ultrasound-guided airway blocks are a newer technique that accurately identifies the landmarks for anesthetizing the superior and recurrent laryngeal nerves.⁶

Technique

Using a Fiberoptic Bronchoscope

• Keep the bronchoscope taut between your hands so the orientation of the tip is the same as the control lever.
• To change the angle, rotate the scope right or left. Can move the lever on the side up or down to change the vertical view.
• It is vital to take your time and go slow; slow is fast.
• Since the patient is awake for intubation, every breath changes the view. It is important to be adaptable and adjust the view as needed.
• Asking the patient to take a breath can help find the airway. Can use air bubbles created by breathing to orient yourself in the airway.

Advancing the ETT

• Use a generous amount of lubrication on the tip of the tube to help advance it through the airway over the fiberoptic scope
• Advance the ETT all the way to the carina with the fiberoptic scope still in place
• Tubes with smaller diameters should be considered when using fiberoptic intubation.
• The Parker tube is a good choice due to its soft, pliable tip, which hugs the scope.
• If the tube becomes stuck (often on the arytenoids or due to swelling within the airway), it can be helpful to rotate or corkscrew the ETT as you advance.

Removing the Fiberoptic Scope and Induction

• Ensure the tube distance from the carina is checked before removing the fiberoptic scope
• After checking the tube position, remove the fiberoptic scope
• Connect the ETT to the circuit and confirm the presence of CO₂
• Administer the IV induction agent and turn on the inhalation agent