Tag: airway

Posted on

Notes from the Practical Emergency Airway Management course

I was recently able to attend the Practical Emergency Airway Management course in Baltimore.

Now 17 years old, this class is the brainchild of Dr. Richard Levitan (emergency physician and legendary airway educator), and is offered every month to small groups — around 20 learners — including emergency physicians, intensivists, and paramedics. Topics range from the physiology of oxygenation to the use of a wide variety of laryngoscopy and endotracheal tube delivery devices (bougies, bronchoscopes, and everything in between).

Other airway courses exist, many of them a little more mainstream and commercial, such as Ron Walls’s Difficult Airway Course (which is run nationally and has its own smartphone app). Two things distinguish this course from the alternatives:

  1. The instructor. Dr. Levitan has been studying and teaching airway management for decades, and is one of the true innovators of the field, a rare individual who is repeatedly willing to revert to first principles and reinvent how we’re doing things. As both a clinician and an ardent student of the human airway, he has popularized many tools and concepts that have become influential in emergency airway management, including apneic nasal oxygenation (NODESAT), “straight to cuff” stylet shaping, external laryngeal manipulation, and slow, methodical, epiglottis-focused laryngoscopy. He has developed his own cricothyrotomy blade, his own optical stylet, and recently his own bougie. He also invented the Airway Cam, a head-mounted camera that places a lens directly in front of the intubator’s eye to record “first person” footage of the peri-intubation airway, a remarkable teaching tool.
  2. The cadavers. Unlike almost every other airway class, which typically relies upon models and mannequins for psychomotor training, the Baltimore course uses specially-prepared cadavers that retain normal physiologic turgor and texture. With one cadaver per learner, techniques can be practiced dozens if not hundreds of times, on 20 different anatomic specimens closely mirroring clinical conditions. This offers a training environment that is literally better than real life, because real-life airways are high-stakes situations with little opportunity for experimentation or failure.

This is not a review, but here are my general impressions of this two-day course:

  • The skills portion of this course was absolutely unique. I know of nowhere else you can get this kind of hands-on airway practice. It alone is worth the (substantial) price of admission, and the 5+ month wait time to book an open course.
  • The didactic portion was strong, but less crucial. If you are familiar with Dr. Levitan’s work, much of which has become widely popularized in the FOAM community, some of it will be familiar. Overall it was a fairly informal program and not the most organized and structured curriculum.
  • It is definitely not for beginners. The raw basics of airway management (this is a laryngoscope, this is the airway, etc) are not covered. The best audience is probably those who have their initial training, have spent a little time in the trenches, and want to take their assorted experiences and shape them into a new, superior model for doing things. (Several emergency medicine residents were there, all of them PGY-3, which seems about right.)

Here are some assorted notes from the course. These are certainly not comprehensive, and were taken for my own use; ideas that were already familiar to me didn’t make it onto paper. They are also my own interpretation and not words to be placed in the faculty’s mouth. For the proper experience… buy yourself a ticket.

Mindset and approach to the airway

    • The key to learning a complex process is incrementalization into small, discrete, learnable steps. But make sure the first step is correct and feasible. If it’s not plausible in many cases (e.g. finding the cricothyroid membrane in an obese patient), when under stress you’ll likely never attempt it, and hence never get past the first step.
    • The response of many providers to failure to intubate or ventilate is to try harder. Trying harder doesn’t help if you’re doing it wrong.
    • Why do airway algorithms include “call for help”? Why is it plausible (and it is) that one competent provider will succeed where a second competent provider failed? Because airway has been taught and learned in a very anecdotal, “artisanal” way. Everyone’s approach is idiosyncratic and unique. This wouldn’t be acceptable for any other high-risk area (would you want your airline pilot to “do it his own way”?). Airway should become a consistent, standardized, reliable process, like pilots with checklists. It should be concrete, methodical, and unexciting, not based on luck or skill.
    • Referring to an algorithm or process as intended for “failed airways” is stigmatizing; it means that if you’re using it, you failed. Likewise, who would want to be intubated by a “crash airway algorithm”?
    • Think of the airway in three levels: upper, middle, and lower. Air must pass all three to reach the blood.

Upper: oro- and nasopharynx and hypopharynx. Maintain patency by placing an oral/nasal airway or simply blasting oxygen into the nares with enough pressure to splint open the soft tissue, and then pulling the mandible forward to open the hypopharynx.

Middle: the trachea. This is inherently patent except where foreign bodies, trauma, or pathologic anatomy (tumors, epiglottitis) enter the picture… which is bad. Middle airway disease is scary.

Lower: the alveoli. These are only “patent” if you remove external compression (sitting the patient up helps) and/or add positive pressure (PEEP).

    • Thus, a reasonable method for oxygenating the transiently apneic or hypoxic patient with otherwise normal lungs (i.e. procedural sedation that gets out of hand): blast O’s up the nose, sit them up, and pull on the mandible. All three segments of the airway are now open and high-concentration oxygen will reach the alveoli, and hence will oxygenate them regardless of whether they breathe or not.
    • There are two priorities in airway management: 1) Oxygenation, and 2) Avoidance of vomit (which compromises every portion of the process). Ventilation is usually only important in severe metabolic acidosis.
    • Do all your procedures sitting up. Lying flat is almost always undesirable. If you need to mask ventilate while seated, hold a two-hand grip from the front with thumbs up while someone else squeezes the bag.
    • You can’t really fool yourself into having confidence if you lack competence. Instead, develop your internal model for the process so you’re never worrying, you’re just working on the next step. Big picture thinking without a strong mental model just leads to anxiety.
    • Rather than worrying about failure, believe based upon your training and knowledge that you’re doing the right thing for the patient, focusing all of your expertise into this moment, that you’re fully committed — and then take it one step at a time.

Oxygenation and Vomit management

  • The head should always be elevated above the stomach. Otherwise stomach contents passively/actively aspirate. If you need to elevate the legs for some reason, also elevate the head (the Pringle position).
  • With a high minute ventilation, a non-rebreather mask at 15 LPM may only provide about 50% FiO2 due to rebreathing. Holding it off the face so they can exhale past it to one side and inhale from the blowby may actually yield higher FiO2.
  • How to open the upper airway:
    • Tilting the head: no effect on airway
    • Chin lift: helps some
    • Mandible thrust: works well
  • FRC
    • Normal: about 2.4L
    • When supine: you lose .8-1.0L
    • When under anesthesia: you lose another .5L
  • In obesity, a head-up position is key, but reverse Trendelenburg is even better.
  • LMAs rely upon the anterior airway collapsing into the bowl to form the seal, so they are actually enhanced by a supine position and sedation.

Nasal oxygenation

  • Nasal oxygenation is actually better when you inhale through nose, exhale through mouth like an athlete; this avoids rebreathing.
  • Positive pressure helps maintain nasopharynx patency, but collapses the oropharynx.
  • Nasal cannula under a BVM with PEEP valve provides continuous PEEP, similar to an anesthetic circuit with blowthrough and CO2 absorption.
  • Bag-mask ventilation as a rescue maneuver for apnea, such as during procedural sedation, is not a great technique; it’s too slow and tricky. O’s up the nose, pull the jaw, sit them up instead.
  • Run your nasal cannula at 4-6LPM for routine purposes, at 15LPM or all the way up to flush rate if they’re crumping.
  • OPA/NPA usually not necessary if brisk nasal oxygenation is present.
  • Patel’s THRIVE protocol for upper airway obstruction was to paralyze the patient (actually improves patency of stridulous airway, due to removing negative pressure), apply HFNC, pull the mandible, sit them up to 40 degrees. This would maintain SpO2 up to 60 minutes in some cases.

Laryngoscopy

  • Both eyes may be open, but you only use one due to the narrow viewing angle; the other is negated with “binocular suppression.”
  • Laterality: most of us have “lateral consistency” (right-handed, right-footed, etc), but sometimes we prefer our off-eye due to differences in acuity.
  • Possibly the ideal blade: a low-flange Mac 4 blade with video capability. Gives enough blade to use Mac as Miller, as well as the backup video option.
  • 3 stages to intubation: epiglottoscopy, laryngeal exposure, tube delivery. Each has separate challenges and should be incrementalized.
  • 4 steps to the “kata” of epiglottoscopy and laryngeal exposure:
    • Insert blade with delicate, two-finger grip, not engaging the tongue, just gently advancing along the midline, passing the uvula and finding the epiglottis. Insert the blade into the vallecula.
    • Shift your grip to a full-hand grip to apply power. Elevate the epiglottis.
    • [If necessary] Bimanual external laryngeal manipulation to improve exposure.
    • [If necessary] Dynamic head elevation with your off hand to improve exposure. Difficult in the very obese.
  • The epiglottis is the key to the airway. It is centered in both axes and is the only structure you can lift out from the posterior tissues, even when they are mired in blood/secretions.
  • Many errors are created early, by overgripping the scope — this creates tension, and you tend to either overshoot (sink the blade too deep, miss the epiglottis and see only pink), or engage the tongue too early, which limits movement. So, hold lightly until you reach vallecula.
  • The vocal cords are a 3-dimension structure with a lot of depth; this is not appreciated in your monocular laryngoscopic view.
  • Head-forward position improves mouth opening, alignment of airway axes, and expands the thyromental space for the tongue.
  • Start in the midline. Don’t worry about tongue control until you reach vallecula and begin the process of laryngeal exposure.

Tube delivery

  • Basics:
    • Straight-to-cuff tube shape
    • Insert and immediately angle below your line of sight, and then let the tip pop up as you reach the glottis, so it only obstructs your view at the last moment
    • Insert from the right side of the mouth, paraglossal if possible
  • ETT tips are beveled to the left. If they catch on the anterior tracheal rings (less likely if your coude angle is not too acute, but still possible), rotate the tube to the right to place the flat side of the bevel against the rings, then advance.
  • Managing a dental gap: consider a bougie, or go paraglossal with a straight blade.

Video laryngoscopy

  • A Mac blade for DL plus a VL device are not good sole backups for each other, because they are both indirect elevators of the epiglottis, and hence fail when this is impossible (distorted anatomy such as epiglottitis, tumors). You should have a straight blade available too.
  • For floppy or Omega-shaped epiglottises, you can also consider using your blade as a Miller to lift it directly.
  • Difficulty with tube delivery using a hyperangulated scope (e.g. Glidescope with Gliderite): once past the glottis, take an overhand grip on the tube and rotate the entire thing 90 degrees to the right. This will put the bevel of the tip against the anterior rings. Now use your thumb to advance the tube off the stylet until it slides freely. You can do this without assistance.
  • If you engage the tip of the Glidescope too early into vallecula, the camera will still be pointing down, so you won’t see glottis. (Glidescope 4 has too long of a tip and often has this problem.) But engage too close, and elevate the epiglottis too much, and tube delivery becomes difficult. Back it off to make the curve and entry angle less acute. If you can see the cricoid on the anterior wall through the cords, you’re too close (i.e. looking too acutely upward).
  • The 50-50 rule: you should have about a 50% view of the cords (50% POGO), which you should position in the top 50% of your screen.
  • If you have difficulty identifying structures during VL, remember: the epiglottitis will be the only horizontal line you see.

Pediatrics

  • Views are usually technically easier.
  • Easy to override structures; go slow.
  • Consider a straight blade, as the epiglottis is long, and the thyromental distance (space for displacement during indirect elevation) is short.
  • When to consider a curved blade: if there are fluids (helps lift the epiglottis away from them), or foreign bodies (creates more space by curving away and exposing right side of mouth).
  • Generally, always use a cuffed tube, as it reduces air leaks.
  • If age >8, manage as an adult airway.
  • Surgical airways: unlike adults it is fairly easy to penetrate the back wall of the trachea. Consider a scalpel/finger/bougie technique with a pediatric bougie (outer diameter 2.5mm, will fit a 2.5 ETT). You may want a tracheal hook, as the cartilages are all pretty soft, including the posterior ones.
  • Pierre Robin and Treacher Collins: consider awake intubation, or HFNC. Hard to both mask-ventilate and intubate. Suction aggressively if secretions are present.
  • Downs: macroglossia, but otherwise usually okay airways.

Pharmacology

  • Before induction, have IV fluids actively running. Other than providing preload, it confirms patency of your IV, which you may otherwise discover too late to have failed.
  • Consider the shock index as a way to evaluate for peri-intubation hypotension risk. If heart rate > systolic pressure, be careful. Have your pressor already prepared. Even ketamine has less hypertensive and more hypotensive effects with a high shock index.
  • Paralyzing: push the rocuronium, ask a nurse to time 60 seconds on the clock (you are bad at estimating time). Then give a couple breaths just to confirm to yourself and others that you can mask-ventilate them if necessary. Then intubate.
  • If no IV access, succinylcholine can be given IM — about 4mg/kg.
  • In status epilepticus, consider induction with thiopental. There is some temporary unavailability due to its role in executions, but it is being reformulated (and will be less alkalotic).
  • In hypertensive neuro patients, consider etomidate for induction — you want hemodynamic stability, not something to dramatically normalize them.
  • In neuromuscular disease, even non-depolarizing NMB can cause prolonged blockade; best to avoid paralyzing completely, if possible.
  • Propofol combined with dense calcium channel or beta blockade (e.g. overdose) can cause cardiac arrest via hypotension, because of its independent effects blocking both channels.
  • Sux is the most oxygen-depleting paralytic, consuming O2 both at the time of fasciculation and when paralysis resolves.
  • Severe hyperthermia: double/triple all med doses, due to rapid circulatory time.
  • Vecuronium can be used for RSI. For rapid effect, double or triple the dose.
  • Severe acidosis: try to avoid paralysis, to permit the patient to continue respiratory compensation. Consider ketamine, which should preserve this. Remember the risks of poor exposure and aspiration without paralysis.
  • If you choose sux, miss the attempt, and need to redose, remember that the second dose may be different, and may need atropine.
  • LMAs should not be used if the patient may gag, as vomit will clog it, wreck the ability to seat, and generally ruin things. So in a tricky airway rescued by an LMA, roc is a better choice than sux, so they don’t start vomiting while you’re readying another attempt.

Lessons from the cadaver lab

  • Bougies do click on the anterior rings, but you may only notice if you use them a lot and practice recognizing this — it is subtle.
  • Bougies will only click if the coude is pointed upward. If you hold like a pencil, it can rotate downward without you noticing. Use a grip that maintains directionality.
  • Tube delivery:
    • Hangs up while sliding over a bougie (on arytenoids): rotate 90 degrees left (counter-clockwise).
    • Hangs up after entering trachea (on anterior rings): rotate 90 degrees right (clockwise).
  • Head elevation has a tremendous effect on visualization. With time, flaccid tissue, and numerous cadavers, you can really appreciate this; the trachea is indeed truly oriented anteriorly, and if you simply lift the head from the flat plane, the axes line up, and what was a very difficult “anterior” airway can become a straight, gaping, cavernous tunnel.
  • With that being said, dynamic head elevation takes some muscle. Start with padding to a sniffing position and you will only need to do it (i.e. additional elevation) infrequently.
  • Everyone teaches the laryngoscope “cheers” as a completely straight motion without wrist rotation, but a slight rotation (angling the tip up a little into the vallecula), without levering off the teeth, can make a much bigger difference in laryngeal exposure than many pounds of straight lifting.
  • Similarly, Levitan and others now teach a fairly flat head posture (shifted anteriorly but not extended); however, I find that at least a slight atlanto-occipital extension helps with visualization.
  • Even hyperangulated VL blades can be used for direct epiglottis elevation (Miller style), which can help a lot in some cases. In extremis they can also be used as DL blades, albeit bad ones.
  • Tomahawk intubation is hard. Like intubating in a mirror.
  • Optical stylets are cool and an unobtrusive way to simplify a tricky intubation, but seem to have a slim role if VL is readily available. Do normal DL, glide in the preloaded tube hugging the blade (to avoid soiling the tip in secretions) until positioned just before the epiglottis, then look into the lens and guide it through the glottis. The tip is quite easily soiled in wet airways.
  • Things I will not be adding to my armamentarium unless my practice environment changes dramatically:
    • Miller blades
    • Flexible endoscopic intubation
  • Channeled VL devices work, but certainly have a different technique and a learning curve involved.
  • Surgical cric lessons:
    • Tracheas vary widely. If you palpate enough, you can start to understand where the cricothyroid membrane lies, which may not be where you initially would have thought. In other words, some people have multiple “bumps” and “soft spots” between them.
    • Thus, follow the dictum: don’t find the membrane, just find the midline and cut. Once you dissect down, the membrane is much easier to identify.
    • With little subcutaneous tissue and a good hole, it is easy to directly insert the tube. But in some necks, it seems like you’re up to your elbows by the time you even reach the trachea. Some tracheas are also very mobile and don’t stay in place for you. In these necks, a bougie first to guide your tube is absolutely essential.