The ancient Egyptians figured this out when they built the Great Pyramids thousands of years ago. They used tools to work smarter, not harder.
Intubation is the same way; for years I’ve been watching students and experienced providers in labs and in the field do the same exact thing as the guy moving the furniture. The more frustrated they get, the more brute force they apply and the worse the situation gets. It isn’t until they slow down and begin to work smarter that they begin to have success. There are numerous ways that prehospital providers can gain mechanical advantage and optimize our laryngeal view. We have to understand which tools to use for this each patient during each intubation attempt. Choosing the right blade or techniques is important, as is understanding that some patients or situations dictate other options, such as blind-insertion airways or video laryngoscopy. Video laryngoscopy uses a camera and a video monitor to visualize the airway and the glottis, enabling faster intubation when you’re dealing with difficult airways in which you can’t get good line-of-sight visualization.
People have been placing metal sticks in mouths for centuries to examine the oral pharynx, and inventors have been keeping pace by creating a bigger and better device at every turn. But let’s stop and consider what we are really trying to accomplish with direct laryngoscopy.
Four Steps for Direct Laryngoscopy
Step one is to move any obstacles, such as vomit, food or teeth, out of the field of view with good suction. Trying to visualize an airway through all that stuff is like trying to drive 60 mph in a torrential rain storm without windshield wipers. You’re not going to be able to drive in the rain without wipers, and you’re not going to successfully intubate without suction. The suction unit is our best friend when it comes to airway management for EMS (but it seems to be the one piece of equipment that is left in the truck, missing a hose or uncharged, so it often isn’t there when the need arises).Once we clear the airway, then we’re ready to take a look at the airway.
Step two is to get that first look before anything else gets in the airway. The scissor technique allows us to open the mouth of the supine patient so we can get a great look at the posterior oral pharynx. This is where we begin to identify our landmarks and possible obstructions. Looking straight into the mouth, the first thing we see is the tongue. The size of the tongue plays a part in determining which blade we will use for intubation. If we’re able to see past the tongue, we’ll see the uvula lying in the posterior oral pharynx. As we begin looking into the mouth, we consider the proportion of the structures to the overall space. This helps determine the level of difficulty—or as a good friend always says, “how fun” it will be manage the airway. Once we have a good assessment, we’ll have some idea what tools we might want to use.[poll id=”19″]
Step three is to choose the right tool for the job. Prior even to opening the airway, the experienced provider has already assessed the patient externally to determine the level of difficulty to anticipate and the equipment to use. Several scoring systems out there assess the level of difficulty of an airway. The most common is the Mallampati score, which ranges from 1 to 4 with 1 being the best view and 4 being the worst. Richard Levitan, MD, came up with a great tool that we will refer to as the “Four Ds” for oral tracheal intubation. The Four Ds include distortion, disproportion, dentitions and dysmobility. A good way for a provider to assess the Four Ds is using the 3-3-2 technique, which includes 3 fingers breath between the incisors, 3 fingers from the hyoid bone to the chin and 2 fingers from the floor of the mouth to the top of the thyroid cartilage. The rule of thumb is the fewer the fingers, the straighter the blade. Imagine trying to get a big fat stick in an opening that’s barely wide enough to get the tongue through. Choosing the correct laryngoscope blade will help ensure that our efforts aren’t impeded by the tool.[poll id=”20″]
Step four is selecting an intubation technique. The direct laryngoscope is a lever with a light at the end of it. Unlike a video laryngoscope, which enables users to capitalize on a superior glottic view and access provided by the video image, direct laryngoscopy doesn’t allow us to look around corners. Therefore, we must have a good understanding of the anatomy to correctly place and use it. The first obstacle that we must move with our lever is the tongue. We simply follow the center of the tongue with tip of the blade and gently lift as we advance, and the blade will naturally come to the vallecula at the base of the tongue. Simply pulling the tongue forward and down will displace the tongue and expose the laryngeal structures; veterinarians have been doing that for years to secure airways in large animals. Remember the laws of physics—every action has an equal and opposite reaction. This means that whatever you do with the handle of the blade will move the other end of the blade. Remember you can’t look around corners so trying to play seesaw or rocking back toward the teeth is only going to impede your view.
Relax & Recall Your Anatomy Lessons
Remember to work smarter, not harder. When I teach together with my flight medic friend of mine (the one who grades intubation difficulty in levels of fun), he always says, “Relax. Your most important decision in your shift is what’s for lunch. This will pass.”
So relax and take a deep breath. If you’re one of those folks who needs to take a death grip on the handle and your arm shakes when you intubate, try a pediatric handle and hold it with two fingers and your thumb toward the base of the blade. Great. Now imagine those ancient Egyptians again moving large stones with a lever. They didn’t move it by rocking back; they lifted up and forward. so place the laryngoscope blade at the base of the tongue and lift up and out to move it out of the field of view to visualize the laryngeal structures.
I tried every trick and gadget I could find for years, but they never seemed to work and all I did was get frustrated. I was told if you drop the head of the patient off the end of the stretcher or prop up the shoulders, it would make a better view—wrong. It wasn’t until I started to study the anatomy and consider what I was trying to accomplish that I realized that all I was doing was moving all the structures into my field of view, requiring me to move them even farther to get that good look at the larynx. However, if the patient’s condition will allow, then raise the head to bring the ears even with the chest, thus aligning the axes to allow for a better view.
Success Is As Easy As…
Finding your success is as easy as following this simple rule: Don’t block your view. Keep the blade at an angle to maximize the field of view by sweeping the tongue to the left and slightly turning the handle toward the left. Make sure when inserting the tube to keep the tube to the right side of the mouth, and watch the tip advance through the glottic opening. One technique for advancing the tube is the hook method, simply sliding the tube into the oral cavity from the right corner of the mouth.
If you understand the anatomy and the mechanics of direct laryngoscopy, your success rate will greatly improve. Remember that intubation is a finesse skill, not brute force, so relax and work smarter, not harder.
Jim Radcliffe, MBA, BS, EMT-P