Soot in the Airway: A how to guide on Fiberoptic Intubation

Author: Brendan Barrett, MD, PGY-4

CASE:

A middle-aged patient was brought to an ED by EMS after a house fire.

  • Primary survey was notable for an intact airway, with a speaking, well-oxygenated patient, but the patient complained of a hoarse voice and throat pain.
  • A small amount of soot was noted on the tongue and the nares.

After discussing the situation with the patient and obtaining verbal consent for sedation, a scope, and possible intubation, he was given:

  • nebulized and viscous lidocaine for topical anesthesia,
  • 1 mg IV midazolam for sedation
  • 10mg IV dexamethasone, and
  • nebulized racemic epinephrine.

The patient’s airway was visualized with a flexible video bronchoscope. See Figure 1 for normal airway anatomy and Figure 2 to see the patient’s anatomy (posted with permission):

Figure 1: Normal airway anatomy
Figure 2: Patient’s anatomy (appears upside down relative to typical laryngoscope view as it was performed by standing in front of the seated patient)

The laryngeal inlet was noted to be markedly edematous, and more soot was visible in the larynx (See Video 1 below).

  • Patient given 1 mg/kg of IV ketamine for additional sedation.
  • Intubated using a pre-loaded endotracheal tube passed over the video bronchoscope.
  • The patient was extubated on hospital day 5, and discharged home on hospital day 8.
Video 1: Flexible Video Oral Bronchoscopy revealing edema and soot in the larynx.

DISCUSSION

What is video bronchoscopic/fiberoptic intubation?

  • Fiberoptic intubation used to refer to using flexible glass fibers to visualize a difficult airway rather than a laryngoscope.
  • Flexible video bronchoscopes use a video camera rather than the flexible glass fibers of traditional fiberoptic bronchoscopes, but the intubating technique when using a video bronchoscope is essentially the same as when using a fiberoptic bronchoscope.
  • Video bronchoscopic/fiberoptic intubation uses a bronchoscope as a stylet, instead of the traditional laryngoscope (See Figure 3 below).
  • Although traditional induction/paralysis can be given, usually the goal in video bronchoscopic/fiberoptic intubation is to NOT take away the patient’s respiratory drive, due to their anticipated difficult airway.
  • This goal can be achieved by keeping the patient fully awake with only topical anesthesia, or by using sedation that does not take away the respiratory drive.
Figure 3: Still from a NEJM video showing a pre-loaded endotracheal tube on a fiberoptic bronchoscope.

Indications for video bronchoscopic/fiberoptic intubation:

  • Anticipated difficulty with mask ventilation in the event of a failed airway:
    • could be from angioedema, epiglottitis, morbid obesity, neck tumors/abscesses, airway swelling from smoke inhalation or other exposure
  • If the patient cannot open their mouth enough to fit a laryngoscope

Contraindications to video bronchoscopic/fiberoptic intubation:

  • If the patient is too unstable to wait several minutes while equipment is set up, traditional laryngoscopy is likely faster
  • If the patient cannot cooperate

How to perform video bronchoscopic/fiberoptic intubation:

  1. If possible, try not to do this alone, and make sure you have at least practiced with the scope beforehand.
    • If you have anesthesia or ENT available, have them there to help if needed.
    • Have your respiratory therapist available, and tell the ICU.
    • Your goal is to not take away the respiratory drive and thus to not have made things worse if unsuccessful… but as this is an anticipated airway disaster, be ready for regular RSI if the patient crashes, and for a surgical airway.
  2. The patient should remain in their position of comfort, whether sitting upright or supine.
  3. Choose nasal vs oral:
    • Nasal route requires more topical anesthesia and is longer, but precludes the patient biting.
    • Can choose the more convenient nostril by occluding one nostril at at time and and asking the patient which nostril is easier to breathe through.
    • You can also try putting a pinky finger with viscous lidocaine into the nostril – if a small finger does not fit, consider whether or not your endotracheal tube will fit.
  4. Topical anesthesia (lidocaine) – The lidocaine can be sprayed into the naso/oropharynx, atomized, nebulized, gargled, and/or even injected transtracheally.
    • There is evidence that sprayed or atomized lidocaine is preferable to nebulized lidocaine.
    • If nebulizing, 4% lidocaine is better, but often only 2% is available.
    • Be careful to keep track of how much lidocaine is given to avoid lidocaine toxicity.
  5. If you have time, you can use glycopyrrolate (0.004 mg/kg, or just go with 0.2 mg) to dry out the oropharynx
    • But this will require 5-10 minutes to work
    • May have to come from pharmacy
  6. Restrain the patient’s arms (requires a cooperative patient), in case at the last minute they become uncomfortable and try to pull out the scope.
  7. Pre-load the ET tube on the scope.
    • Use a small amount of lubrication to help the tube slide over the scope more easily.
    • If you forget this step, you may have to cut the scope once it is through the cords and use the cut scope as a bougie – no big deal if you are using a single-use flexible video bronchoscope.
  8. Sedation – if you are using a video/fiberoptic bronchoscope because you are concerned that you could have a hard time ventilating this patient, you do not want to take away their ventilatory drive.
    • Ketamine is thus a good sedative choice.
      • Can give 1 mg/kg to dissociate the patient while maintaining their respiratory drive, or you can give smaller pushes.
    • Midazolam may also work.
    • An extremely cooperative patient may not require sedation at all, although this is not the norm.
  9. Insert the scope.
    • Keeping the scope taut at all times to allow easier maneuverability, regardless of whether the oral or nasal route is used, or seated or supine positioning.
    • Once through the cords, go all the way to the carina.
    • You do not want to be just barely through, in case anything moves.
    • Railroad the pre-loaded endotracheal tube over the video bronchoscope/fiberoptic bronchoscope to the appropriate depth, and then withdraw the scope.
  10. Inflate the balloon, and confirm ETT placement.
    • Give more sedation now that the airway is secure.

References:

  1. Netter FH. Atlas of Human Anatomy. 6th ed: Saunders; 2014.
  2. Heidegger T. Fiberoptic Intubation. New England Journal of Medicine 2011;364:e42.
  3. Sukhupragarn W, Leurcharusmee P. Lidocaine post-nasal dripping (LPND): An easy way for awake nasal intubation. Journal of Clinical Anesthesia 2018;44:105-6.
  4. Dhooria S, Chaudhary S, Ram B, et al. A Randomized Trial of Nebulized Lignocaine, Lignocaine Spray, or Their Combination for Topical Anesthesia During Diagnostic Flexible Bronchoscopy. Chest 2020;157:198-204.
  5. Madan K, Biswal SK, Tiwari P, et al. Nebulized lignocaine for topical anaesthesia in no-sedation bronchoscopy (NEBULA): A randomized, double blind, placebo-controlled trial. Lung India 2019;36:288-94.
  6. Cho EA, Hwang SH, Lee SH, Ryu KH, Kim YH. Does glycopyrrolate premedication facilitate tracheal intubation with a rigid video-stylet?: A randomized controlled trial. Medicine (Baltimore) 2018;97:e11834.
  7. Weingart S. Podcast 145 – Awake Intubation Lecture from SMACC.  EMCrit-RACC2015.

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