The ability to perform endotracheal intubation is a critical skill. There are three types of emergency intubations:
(1) A crash intubation where the patient is unconscious and apneic and needs immediate intubation without any pharmacologic therapy.
(2) Rapid sequence intubation where the patient is conscious and breathing and is given medicines that renders the patient temporarily unconscious and apneic in order to perform the intubation.
(3) An awake intubation where the patient isconscious and breathing and is given a local anesthetic that allows the intubation to be performed with the patient awake.
An awake intubation may be the best option whenever there is a question of a difficult intubation because if the doctor can’t pass the ET tube into trachea, at least the patient is still breathing.
Before performing any rapid sequence intubation, the doctor evaluates the patient to see if he or she is likely to be difficult to intubate. If evaluation suggests a difficult intubation, the physician seeks immediate consultation from another physician, perhaps an anesthesiologist. But often, no one else is available. The doctor (and the patient) are on their own.
In this case, the best course may be to do an awake intubation. And now there is a outstanding eight minute how-to video on awake intubation available at http://emcrit.org/misc/awake-intub-video/ by Doctor Scott Weingart.
He has also completed an outstanding thirty minute video lecture on awake intubation available at http://vimeo.com/2546522.
The steps of a successuful awake intubation are:
(1) Dry out the mucosa
(2) Suction the mouth and wipe tongue and cheeks
(3) Give topical anesthesia to the tongue, mouth, and throat
(4) Give viscous lidocaine to the back of the throat
(5) Transtracheal injection of lidocaine (NOT Recommended) instead
(6) “Transtracheal Trickle” (Dr. Weingart’s term)
(7) Preoxygenate (8) Sedate (9) Use video larygnoscope (e.g. Glidescope) if available and pass a boughie through the vocal cords.
(10) Place the endotracheal tube over the brougie and pass it through the vocal cords into the trachea. And do post entubation management.
Going over the steps, Dr. Weingart makes practical points about each step.
Step 1: Dry out the mucosa
This step is necessary because otherwise the topical lidocaine will never get through all the mucous in the mouth and throat to anesthetize the mucosa.
Use either glycopyrolate 0.2 mg IV or atropine 0.01 mg/kg IV. Dr. Weingart recommends glycopyrolate because it doesn’t pass the blood-brain barrier and so has no central effects. It takes 15 minutes to get maximal drying effect and it takes at least 5 minutes for it to take effect. It won’t work in one minute so as soon as you think you might need to do an awake intubation, go ahead and give the medicine. If it turns out that you can safely due a rapid sequence entubation no harm is done.
Step 2: Suction the mouth and wipe tongue and cheeks
Suction the mouth with a yonker suction tool and wipe the tongue and cheeks with four by fours to further dry the mucosa. The mucosa must be dry for the local anesthesia to work.
Step 3: Give topical anesthesia to the tongue, mouth, and throat
Give 6 to 8 cc of 2% lidocaine by nebulizer with the flow rate set at 5 liters per minute by mouth piece or mask. The flow rate shoud be kept low so that the particle size is large and so stays in the mouth and throat.
Or give 4 cc of 4% lidocaine by nebulizer with same flow rate. 4% lidocaine is usually not available but 2% will work.
Or give lidocaine spray if there is no time for nebulizing.
Or give lidocaine by a mucosal atomization device which is simply a long thin tube whose tip generates a fine spray. This thin flexible tube attatches to a regular syringe. “You can spray the entire airway with this.”
Do not use cetacaine as it can cause methemoglobinemia.
Step 4: Give viscous lidocaine to the back of the throat
“Next, to try to get the top portion of the epiglottis and sometimes even get into the cords themselves I make the lidocaine lollipop,” Dr Weingart says.
Take a big blop of viscous lidocaine 2% on the tip of a tongue blade and place the lidocaine side down on the back of the tongue “and put it back as far as you can–all the way to the back of the throat.” “Tell the patient not to swallow [and] it slowly falls down the back of the tongue into the pyriform sinuses and the top of the epiglottis and sometimes even get into the cords themselves and tell them not to swallow. When it is all absorbed then have the patient gargle with it.”
Step 5: (In the old days) you might do a transtraceal injection of lidocaine—DON’T.
Step 6: Instead, Dr. Weingart recommends the “tracheal trickle”.
You use a syringe with 4 cc of 2% lidocaine and a 14 or 16 gauge angiocath without the needle. “You push the angiocath in so it is draining right over the back of the throat.”
“Holding the patient’s tongue [as far as you can] with a gauze pad, very slowly trickle lidocaine in 1. to .2 cc increments in the back of the throat. Time the injection of each increment to coincide with inspiration. Pause for a minute after the first 2 cc but to continue to hold the tongue to prevent swallowing.”
Be aware of lidocaine toxicity.
Step 7: Preoxygenate
Use a non-rebreathing mask. When you’ve got adequate pre-oxygenation, switch to a nasal cannula before intubation—that way the patient is getting some oxygen while you are performing the intubation.
Step 8: Sedation
If you’ve done your local anesthesia correctly then the entire airway up to the cords is anesthetized. But sedation gives us a last little bit of help.
The video discusses what you should use for sedation and gives excellent details—see the video for dosing. Also see blog post of March 26, 2012 for the details on sedation. Basically Dr. Weingart recommends Versed, a combination of ketamine and propofol in the same syringe, ketamine alone, or dexmedetomidine.
Step 9: Use video larygnoscope (e.g. Glidescope) if available and pass a boughie through the vocal cords. You get a better view with a Glidescope than with a traditional laryngoscope, Dr. Weingart observes. Place endotracheal tube over the boughie
Step 10: Do post entubation management.