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See Cords Around Corners

Posted on 30 August 2012

I knew it was going to be a tough intubation. He was a bear of a man, well over 300 pounds. But compounding the problem was his tiny mouth and diminutive jaw—barely enough mandible to catch on the top of his C-collar. Respirations were agonal and sats were on the verge of precipitous decline. As I scissorred open the teeth, I was dreading the expected view of redundant tissue, blood and saliva, and hoping for the elusive larynx.

The adult Glidescope blades come in two sizes, a 3 and a 4. The 4 is what I use for nearly all adults and is listed as 90 pounds and up. Image Courtesy Graham Snyder, MD

I placed the 4 Mac into the mouth, but it was not good. The man’s jaw and mouth were barely large enough to place the blade between the teeth, yet his tongue seemed gargantuan. The thickness of his torso plus the very real fear of worsening a possible c-spine injury resulted in a view of only a pink wall of tissue.

“Want me to get the scope?” queried the respiratory therapist.

“This is not a candidate; there’s too much blood,” I responded, envisioning the futility of attempting to snake a tiny flexible fiberoptic wire through the patient’s nose or into his mouth–the tissue compressed flat in his supine position and the tiniest droplet of blood or saliva leading to complete loss of view.

“Not the flexible fiberscope, the video laryngoscope,” The respiratory therapist clarified as he placed the plastic blade in my hand and turned the video screen in my direction.

I had picked up the Glidescope a number of times at conferences when walking by promotional booths. On a dry plastic mannequin head, it seemed to work spectacularly. The view of the cords was superior to all but the easiest of direct laryngoscopy, and the force needed to obtain that view was a fraction of that needed normally.

But would it work in a high-pressure, high-stakes clinical setting?

The patient was difficult to bag so I had about 60 seconds before I would need a rescue device or proceed to cricothyroidotomy.

I gently inserted the blade sliding down the center of the tongue and in seconds was greeted with a textbook view of not only the larynx, but the arytenoids and the aryepiglottic folds as well! There was four times the amount of information I needed to place an ET tube normally. I grabbed the endotracheal tube, which the RT had preloaded on the strange glidescope stylet, not knowing that my challenge had just begun.

For the past 11 years, I’ve been giving lectures on management of the difficult airway to the right students at the wrong time in their career. Learning direct laryngoscopy and effective placement of an endotracheal tube is a challenge in itself. When you add the extreme stress and anxiety of a horrifically unstable patient, it’s a wonder we can pull it off at all. However, with the combination of good lectures, operating room and/or simulation time, we all learn the art. Once you become proficient, in truth, it’s not that hard…except when it is.

The majority of difficult airways occur because of an inability to visualize the vocal cords. Usually, this is not a surprise. The causes are innumerable and sometimes additive. Even before beginning the procedure, when a patient has a small mouth, a large tongue, and a short jaw, you should anticipate a difficult airway and make plans for managing it.

There are plenty of other options, including lighted stylets, retrograde intubation and LMAs. The most important thing is that you be well practiced in the technique so that when the time comes, when the stakes are the highest, you are relaxed, confident and proficient.

This is just as true when using video laryngoscopy, and is often ignored because at first glance it seems both very similar in the technique we are all confident in (direct laryngoscopy) and is easier than direct laryngoscopy. This is true, BUT if you do not make the appropriate modifications to your technique, you will at best struggle and at worst have a failed airway.

Video laryngoscopes allow for spectacular visualization of the larynx often in cases where direct laryngoscopy would be extremely difficulty or impossible. This is best demonstrated by a patient with a small mouth and big tongue, which unfortunately is the case with all infants.

The magic of the Glidescope is you do not have to physically look in the mouth (only at the video screen), so intubation can still be accomplished on these tiny airways as demonstrated below in this 16-month infant simulator. See the video and photograph below.

Intubation can still be accomplished on tiny airways, as demonstrated in this 16-month infant simulator. Photo Courtesy Graham Snyder, MD

Click here for video.

Step 1: Know your Equipment.
There are a variety of different video laryngoscopes, each of which have its own unique performance characteristics. At our institution, we use the Glidescope Ranger. But no matter what you use, you must learn the unique geometry of the blades and significantly different techniques for intubation before the time of crisis. This can be accomplished with a stable patient and bedside supervision with an experienced practitioner—and ideally complemented by both supervised and independent practice using human patient simulators or airway task trainers.

Step 2: Assemble the Equipment Correctly.
There are really only three pieces of equipment. The wand (light source and fiberoptic camera), the plastic blade cover and the video screen. The wand plugs into the video screen intuitively and then the blade cover slides onto the wand with a definitive click. The wand must go in straight into the plastic sheath. If the wand is placed into the blade cover rotating 90 degrees, the screen will be 90 degrees off but in addition there will be extremely distracting glare. Make sure that the writing on the blade cover aligns with the writing on the wand. If you don’t, when you look in the mouth you will not be able to tell whether the blurry spots on the video screen are from saliva obscuring the view or from the plastic refracting.

Step 3: Don’t Look in the Mouth.
The Glidescope looks very similar to a Macintosh laryngoscope, leading people to mistakenly attempt to use it as one but everything is different. For one, the basic maneuver is more of a gentle straight up lift than the diagonal forward movement used in direct laryngoscopy. Also, much more importantly, getting the camera to find the cords has nothing to do with the maneuver needed to directly visualize the cords. Keep your eyes on the camera once you are inside the mouth and guide the video screen toward the cords.

Step 4: Use the Steel Stylet that Comes with the Glidecope.
You will be advancing the tube around and over the tongue and must maintain the curve of the original stylet or else the tube will not be able to find the larynx. If you use a normal stylet, it will get straightened out by the time you get to the larynx and will repeatedly, (and extraordinarily frustratingly) pass into the esophagus. You will no longer have the angle needed to pass into the cords.

Correct Technique

Incorrect Technique

Step 5: Don’t Get too Close to the Cords.
The temptation when using the Glidescope (because you obtain such a gorgeous video of the cords) is to press the camera close to the larynx. If the larynx fills the entire video screen, then the tip of your blade is millimeters away from the larynx. However, wherever the camera is, the tube will come in just below that point so if you’re abutting the cords already, when you pass the tube it will pass just below the cords (into the esophagus). If, however, you back away a little from the cords, then, because of the angle of the stylet, once the tube passes in front of the blade it will angle up and smoothly in between the cords.

Incorrect Technique

Correct Technique

Step 6: Back the Stylet out while Advancing the Tube.
The stylet is quite rigid steel and has nearly a 90-degree curve in it. This works perfectly for making the turn around the tongue and effortlessly going through the cords. However, since the trachea does not have a curve in it, as soon as the tip of the tube is placed between the cords, the stylet must be backed out to allow it to pass. Conveniently, there is a little flip top on the end of the stylet perfectly positioned for your thumb to kick it back and the tube to slide into the trachea. This is not optional. It is physically impossible to pass the tube with the stylet in place, so once the tip is between the cords, you or your assistant must remove the stylet.

Remove the stylet to secue the airway. Photo Courtesy Graham Snyder, MD

Conclusion
In my difficult case, once I took the respiratory therapist’s suggestion, I found the trauma patient’s vocal cords in seconds and with a sigh of relief advanced the tip of the orotracheal tube between the cords. I was puzzled briefly by the resistance I felt when I attempted to advance the tube, when the paramedic who brought the patient in (who was also watching the screen) reminded me, “You have to remove the stylet or it won’t advance.” He leaned forward, and like lighting a Zippo, he flicked the stylet lever (see image at left) backwards and the tube effortlessly advanced securing the airway.

When properly used, the video laryngoscope can transform extremely difficult intubations into nearly effortless lifesaving maneuvers and can be used in easy intubations as a safe and controlled way to teach the art and the science of orotracheal intubation.

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Graham E. Snyder, MD FACEP

Graham E. Snyder, MD, FACEP, is medical director for the Center for Innovative Learning at WakeMed Health and Hospitals.

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Graham E. Snyder, MD, FACEP, is medical director for the Center for Innovative Learning at WakeMed Health and Hospitals.

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