Can awake fiberoptic intubation be fast and easy? With the growing availability of video laryngoscopes and other devices, fiberoptic intubation skills seem to be decaying and perhaps not being mastered at all during residency training. In a closed claims analysis*, even in cases in which a difficult airway was anticipated, the first airway management strategy occurred after ablation of spontaneous ventilation and induction of general anesthesia in the majority (61%) of cases. What is the explanation for this kind of decision making? Perhaps overconfidence plays a role, as difficult airways were suspected and ventilation was ablated regardless. Is it a manifestation of omission bias – the tendency to prefer maintaining the status quo – perhaps related to production pressure and perceived inconveniences to the rest of the OR team? What about loss aversion, in the sense that a rocky awake intubation performance could lead to “looking bad” and perceived or real damage of professional reputation? Whatever the explanation, assuming that we all want to provide the best and safest care for our patients, it is important to develop and maintain skills for intubation during spontaneous ventilation, and also to use these skills. My interview with Dr. Scott Miller of Wake Forest University describes his reliable, rapid, three step technique for airway topicalization for awake fiberoptic intubation.
Dr. Miller, what’s the argument for awake fiberoptic techniques in the modern day? Many anesthesiologists say they’d typically just use a video laryngoscope.
Miller: Three main reasons: First, all tools fail from time to time, and patients are getting more complex, older, and obese, so advanced technology is not failsafe. Second, the best way to avoid the “cannot ventilate, cannot intubate” scenario (CV/CI) is to avoid ablating the patient’s ability to breath until the airway is completely secure. Third, the less often awake intubations are done, the less comfortable anesthesiologists will be in performing awake intubations, leading them to avoid awake intubations, and perpetuating this lack of confidence. This may be the reason that the closed claims database shows that even when an anesthesiologist anticipated the airway was going to be challenging, induction of general anesthesia was done prior to intubation most of the time. In those cases, payouts were especially high. Although we may not be able to completely avoid difficult airways, we can manage them more safely, and with less liability.
Tell us about the development of the technique.
Miller: It was definitely a team approach perfected over the years. My colleagues and I felt it was important to be true to the ASA difficult airway algorithm. The algorithm emphasizes the importance of airway assessment and consideration given to spontaneously breathing techniques. The emphasis we place on efficiency, sedation schemes, and fiberoptic mechanics is what makes this approach unique and takes many of the commonly held barriers to awake intubations off the table.
What are the advantages of this technique, compared to standard topicalization and sedation regimens?
Miller: The emphasis on nerve blocks really plays into efficiency and efficacy. Topicalization, while effective and important, tends to require more “soak” time. One of the biggest causes of airway anesthesia failure with topicalization is not giving it enough time to set-up. The three injection technique we use at Wake Forest has been quite easy to teach and very effective.
What is the most important element of an awake intubation plan?
Miller: Maintaining spontaneous ventilation and cooperation are the two most important goals. The sedation scheme must be directed towards these goals. Ketamine in doses of 10-40 mg combined with midazolam and/or fentanyl seems to provide adequate sedation while maintaining spontaneous ventilation and cooperation. Precedex can also be used if started early. It has a bit of lag time and needs to be started in the holding area prior to arriving in the operating room. Depending on the patient bolus dosing may threaten cooperation and/or spontaneous ventilation. There are many sedation choices, but staying goal directed is most important.
You’ve said that the intubation begins with the patient discussion. How should anesthesiologists present this procedure?
Miller: Many anesthesiologists are familiar with the term “verbal Versed,” intended to describe a conversation that is an anxiolytic exchange. When discussing an awake intubation with the patient, I avoid the term “awake” and instead describe what we are planning to do: placing the breathing tube while the patient is sedated and spontaneously breathing. For example, “Hello Mrs. Jones I’m Dr. Miller, your anesthesiologist. I am a bit concerned about the injury to your neck. I am going to keep you safe and take good care of you. I am going to get you quite sleepy and do a few numbing injections in the front of your neck and your mouth to prevent coughing or gagging. Then I will look down into your windpipe with a small camera-like device, and put in a breathing tube. I will make sure you are comfortable and safe.”
You’ve focused on the ablation of three key reflexes. What are they?
Miller: The most important aspect of successful “awake” intubation is to not proceed without having the reflexes ablated. We break it down into three specific reflexes: periglottic cough, gag, and subglottic cough. Of these, the gag is the most important reflex to ablate when awake oral intubation is being done. This is a useful framework to help anesthesiologists stay focused on the big picture.
(Credit: David Saliba, M.D.)
Ok, let’s walk through how to block each of these nerves.
Miller: First, the periglottic cough: This is mediated through the internal branch of the superior laryngeal nerve. For ease and efficacy we use the thyroid cartilage as the main landmark. 3-5cc of 2% lidocaine can be injected on each side at 10 o’clock and 2 o’clock. We start with this block to give me an idea of the level of sedation. If the patient seems uncomfortable, knowing this early gives me a chance to add more sedation.
Next, the intraoral gag: The anatomy is pretty straightforward. The landmark is the palatoglossal fold i.e. where the tongue meets the anterior tonsillar pillar. 2 cc of 2% lidocaine is injected using a 25g pencil point 3 ½ in spinal needle. This is easiest if one takes a laryngoscope blade along the lower lateral aspect of the tongue and gently retracts medially while advancing posteriorly. The fold is evident between the tongue and tonsil right behind the molars.
This tissue carries the lingual branches from the ninth cranial (glossopharyngeal) nerve, and as such, an injection quickly ablates a gag reflex from lingual pressure. The block works in seconds, lasts about 20 minutes, and is most easily accomplished with a longer needle (like a 25 gauge spinal needle). It enjoys a high success rate because it is anesthetizes a single upstream branch instead of the thousands of pressure receptors within the tongue. Potential pitfalls with this block are that one needs optimal cooperative sedation as well as adequate mouth opening to accomplish it.
Finally, the subglottic cough: This is the classic transtracheal injection done through the cricothyroid membrane. The key to this block is using a large mass of drug i.e. 4cc of 4% lidocaine since it is topicalizing the trachea.
Even with ablated reflexes, many trainees are concerned about fiberoptic scope mechanics – they don’t feel confident “driving the scope”. Can you make this easier?
Miller: We advocate breaking the procedure down into three parts: glottis visualization, glottis advancement, and endotracheal tube advancement. Each of these three parts can be accomplished with some practice. The major advantage of the fiberscope – flexibility – is also the biggest disadvantage. It is important to keep the fiberscope straight and avoid pushing the scope, which creating bending and deviation, but instead pull the scope. This will be clear as the readers watch the video (below).
Step 1: Glottic Visualization Whether using an optical fiberscope (i.e. looking through the eyepiece at the end of the scope) or a video tower, the most important aspects of glottis visualization is keeping the fiberscope straight and midline. We teach not to look through the fiberscope or at the screen until you think you are at the glottis. Some approaches using the fiberscope fail because people try to drive through “spit” and end up off midline. Keep the fiberscope straight, use the fingers of the left hand to rest on the patients face, and keep the right hand on the wheel up by the eyepiece. Incorporated into the mechanics of glottis visualization is a slight bend to make a “soft-J” on the end of the scope.
Step 2: Glottic Advancement: The scope is grasped between the thumb and index finger of the left hand and is pulled toward the glottis, keeping it in the center of the field of view. This “pull” is achieved by using the index finger to advance the scope over the thumb, allowing the fiberscope to remain straight. At the same time, the “soft-J” may need to be relaxed.
Step 3 is advancement of the endotracheal tube.
You have emphasized the importance of matching scope size and endotracheal tube size.
Miller: Yes, use the largest scope with the smallest tube. A 1mm difference between the tube and the scope is an optimal way to setup for successful tracheal advancement. The larger scopes form a bigger and better stylet. For example, consider using a 5.0 mm scope with a 6.0 tube and a 6.0 tube can be used with a 7.0 tube. If all that is available is a small scope consider downsizing to a smaller tube.
What if the scope gets caught in the glottic inlet, or the anatomy is obscured by blood or secretions?
Miller: If the tube gets caught the most important thing is to not panic and try to force the tube. Try rotating the tube so the blue line of the tube is on the patients left side. This will place the bevel posteriorly. This will minimize the likelihood hang up on one of the vocal cords. If problems persist try to downsize the tube and/or scope. If secretions or blood is the problem consider blowing 4-6 L of oxygen through the working channel of the scope. This will help to keep the lens clear of secretions or blood and may improve oxygenation.
And you say even a beginner can do this?
Miler: Yes. This video shows the technique performed on a real patient by a resident who has never done an awake intubation previously.
Also, consider attending our awake intubation workshop at our annual meeting for personal instruction and hands-on training in this technique.
Thank you, Dr. Miller, for sharing this technique.
Dr. Miller is an Assistant Professor of Anesthesiology at the Wake Forest School of Medicine. You can email him at firstname.lastname@example.org.
Reference: Gene N. Peterson, M.D., Ph.D.,Karen B. Domino, M.D., M.P.H.,Robert A. Caplan, M.D., Karen L. Posner, Ph.D., Lorri A. Lee, M.D., Frederick W. Cheney, M.D. Management of the Difficult Airway: A Closed Claims Analysis. Anesthesiology 2005; 103:33–9