Old Problems With New Technology

glottis

With the exploding popularity and accessibility of video laryngoscopy out of the OR into remote locations, emergency departments, and even into the field, the skill of traditional direct laryngoscopy has taken a further backseat in the schoolbus of airway management.  Video laryngoscopy (VL) with its indirect method requiring a modicum more of hand-eye coordination is perhaps a natural extension for those of us who grew up in the digital age of video games.  The steeper and more nuanced learning curve of direct laryngoscopy in the short run seems unnecessary, but I suspect the expert muscle memory of skilled direct laryngoscopy will prove to be more valuable in the long run.

Recently there has been a lot of attention paid to two potential pitfalls of video laryngoscopy.  First is the purported propensity for dental/oral/airway trauma with VL, mostly centering around soft palate and posterior pharyngeal wall trauma either by the video laryngoscope itself or by the endotracheal tube.  The object of VL is to efficiently and easily arrive at a view of the glottic opening, so it’s easy to discount the need to very deliberately and methodically instrument the mouth before getting to the “money shot”.  Additionally, once the glottis is in view during VL, passing the ET tube becomes a largely blind procedure until it also comes into view in proximity to the glottic opening on the video monitor.  Here’s a drawing by Australian ENT surgeon, Dr. Eric Levi, that illustrates the badness:

The second pitfall of video laryngoscopy that is currently making the Twitter rounds is Glottic Impersonation, as reported by Drs. G. Kovacs, L. Duggan, and P. Brindley out of Canada.  They describe the anterior displacement of the trachea with aggressive laryngoscopy or mask ventilation, causing the esophageal opening to be “tented up” and appear very similar in appearance to the glottic opening:

With the widespread popular use of video laryngoscopy, practitioners who would have otherwise triaged the airway to more traditional airway experts are taking things into their own hands.  It’s a testament to the intended accessibility of video laryngoscopy, but I fully expect to see these two pitfalls continue to occur as associated with VL…not because the management of the airway by VL is in anyway in less capable hands.  Rather, it’s the simple fate of history repeating itself with new technology.


Knowing this, what do we do?

One of my first attendings as a CA-1 offered me this admonition as he handed me the laryngoscope: “Here’s your weapon. Use it wisely.”  He didn’t give me a whole lot more to go on, but I got his message loud and clear.  These days, since we are being “kindler and gentler” to residents, I tell them to “Enjoy the view.  And take your time to smell the roses.”  I take my time doing direct laryngoscopy anyway, but I have to admit it’s kinda of fun with the GlideScope…seeing the teeth so closeup and then the tongue with all its tastebuds and then the vallecula of the epiglottis.  It’s rather enjoyable and simple to avoid the airway trauma associated with video laryngoscopy…take your time and watch the tip of the blade the whole way down to the cords.

Glottic impersonation is a slightly different problem…but maybe being “gentler” in the act of laryngoscopy would be enough to alleviate the issue.  Again, it’s not a new problem that only cropped up with video laryngoscopy.  We see this issue all the time in the highly distensible airway tissues of pediatrics…perhaps because we are commonly using oversized Mac 3 or Miller 2 blades to intubate these kiddies.  It’s also used to our advantage in adults when we have trouble passing an nasogastric tube blindly…we use the laryngoscope blade to lift the glottic apparatus anteriorly and tent open the esophageal orifice in order to pass the NG tube directly.

Short of recognizing the issue outright, there are a couple of ways  we can differentiate the trachea from the esophagus if we are faced with the dilemma of choice.  One of the newest methods put forth by its proponents is to do tracheal ultrasound:

That’s a tracheal intubation on the left and an esophageal intubation on the right.  But in my hospital, the patient would most definitely succumb to a hypoxic arrest before we ever found a functional ultrasound to detect an esophageal intubation…really.  So I kind of discount the whole idea.  Your mileage may vary.

giphy

Femoral artery and “winking” femoral vein.

Still, translating what we are more familiar with in ultrasound might help us out.  Think about what you look for under ultrasound when you are inserting a central line or doing a nerve block either in the neck or in the femoral compartment.  We look for a compressible vein next to a relatively non-collapsible artery.  Taking this idea to the airway, we have a semi-rigid non-compressible tracheal structure next to the collapsible esophagus.  Except we don’t need the ultrasound to see this relationship.  We can stare right at it with laryngoscopy.

So the next time you encounter what looks like glottic impersonation and you’re not sure which hole is which, ease up on the force you are exerting with the laryngoscope and see what happens.  Use your own fingers to compress the area vis a vis cricoid pressure and watch the esophageal orifice wink back at you.  At this point, it’s a simple numbers game and you have eliminated the fake.  All that’s left to do is to watch the tube go through the cords.

 


glotticlike01_origAnd Here is Where The Real Problem Lies

My true belief is that with any plan, you gotta have a backup plan.  And that backup plan has got to be foolproof in order to truly serve as your backup.  That means, if you’re counting on Plan B to save your hide one day when Plan A goes south, you better damn well be skilled at executing Plan B.  Otherwise, you’re as good as having no backup at all.

This is how most of us trained as anesthesiologists, getting extremely skilled and comfortable with advanced airway maneuvers, such as fiberoptic intubation, retrograde wire, emergent cricothyroidotomy.  These skills form the backbone of our backup plan, ensuring close to 100% success in establishing and securing an airway if direct laryngoscopy fails.

Personally, I see video laryngoscopy sitting somewhere between direct laryngoscopy and the more advanced and more invasive airway management skills.  It’s a shoehorn for those really anterior airways or really small mouth openings or non-displaceable mandibular spaces.  When it works, it works really well.  And it’s easy to use to boot.  But in general, I still use it as a backup to direct laryngoscopy and bridge to fiberoptic intubation.  For this purpose, I think it is an extremely valuable tool in our practices.

But when you put patients back into the equation, video laryngoscopy may fall victim to its own success on the gameboard of risk.  Because of its accessibility and relatively easy learning curve, more people are taking on the challenge of airway management…people who otherwise would not have been comfortable doing direct laryngoscopy in the same situations.  And the biggest risk to patients in this circumstance is that aside from video laryngoscopy, there exists no immediate and real Plan B as backup.

The above examples of airway injury and glottic impersonation are a good reminder to us that there are caveats to be considered in everything that we do, no matter how simple or safe it appears on the surface.  These are, after all, old problems with old solutions.  Even with new technology, it still pays to be well-versed with old techniques, so that you recognize the old problems when they reappear.  And above all else, make sure that your ability to execute Plan B successfully exceeds your confidence level in Plan A.  Don’t get caught trying to execute a backup plan that doesn’t actually have your back.

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